CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application 63/387,565, filed December 15, 2022. The contents of the referenced application are incorporated into the present application by reference.

BACKGROUND

1. Field

[0002] This disclosure relates to the field of chemistry. More specifically, but not exclusively, the present disclosure broadly relates to a process for the extraction and recovery of nickel, cobalt, manganese and magnesium values from a feedstock. Yet more specifically, the present disclosure relates to a process for the extraction and recovery of nickel, cobalt, manganese and magnesium values from a laterite feedstock using ultrasound assisted extraction. The present disclosure also relates to a process for the extraction and recovery of nickel, cobalt, manganese and magnesium from a laterite feedstock using flash sonication.

2. Related Art

[0003] The following discussion of the background art is only intended to facilitate an understanding of the process described herein.

[0004] The use of rechargeable Li-ion batteries has been growing steadily, and this growth continues to increase considerably as electric cars become more reliable and available, coupled with the increasing demand for off-peak mass electric power storage. Nickel and cobalt are of value in an increasing range of applications, such as for example in NMC lithium ion batteries. Regarding cobalt, it is variously estimated that there will be a significant shortfall of high-purity cobalt feedstocks.

[0005] The majority of the world's nickel reserves are found in silicate mineral deposits, particularly in the form of laterites, termed lateritic nickel ore deposits, and these deposits further include significant amounts of cobalt in the form of Ni-Co laterite deposits. Laterite ores, according to their chemical and mineral composition, are divided into ferruginous (limonite) and magnesium silicate (saprolite) ores. The fraction of ferruginous ores accounts for about 70% of the nickel and of saprolite ores for about 30%. Magnesium silicate nickel ores are commonly processed by pyrometallurgical methods, and ferruginous ores by hydrometallurgical methods. Hydrometallurgical processing of laterite ores is carried out in two variants: sulfuric acid high pressure and temperature leaching (HPAL process); and ammonium-carbonate leaching after preliminary reduction roasting at 650-780°C (Caron process). The latter process is very sensitive to changes in the basic leaching parameters (temperature, ammonium concentration in the solution, etc.); is characterized by a very high energy consumption, in particular due to the need of drying the laterite feed, and yields a modest recovery, typically 75-85% for nickel and 45-55% for cobalt; and poses significant environmental risks. The operation of the HPAL process can be rendered very difficult or even rendered impossible if the starting ore is rich in magnesium or free silica. Moreover, it is very capital expensive because of the high costs incurred by material requirements. The recovery of metallic values from laterites has been disclosed as being improved by subjecting a slurry obtained by leaching of the laterites with sulfuric acid to sonication (US 2015/0267275).

[0006] Challenges remain in the production of nickel and cobalt from laterites. Hydrometallurgical approaches, including high pressure acid leaching (HPAL), can suffer from complications affecting the treatment of different laterite layers (typically made up of saprolite-type ores as distinguished from limonite-type ores). Moreover, since nickel in laterite ores is typically found in combination with iron(lll) oxides/hydroxides or with silicates, it cannot be selectively separated and concentrated by ore dressing techniques. Physical separation techniques, including sizing and classification as well as gravity and magnetic separation, either individually or in combination, do not lead to dramatic grade increases of nickel laterites.

[0007] Sulfate-based atmospheric leaching can be conducted at low temperatures and in open vessels. However, the slow kinetics of nickel extraction and the presence of soluble iron in the leachate solution requires that the leachate be subsequently further processed. In addition to the high cost of hydrochloric acid, chloride-based atmospheric leaching requires that significant corrosion precautions be taken.

[0008] With the exception of the Bou Azzer deposit in Morocco, which accounts for about 0.3% of the world’s production, there are no primary cobalt mines operating, with the metal generally being recovered as the by-product of copper (predominantly the Central African Copperbelt) or nickel (Canada, Western Australia, Russia) mining. With the former, the cobalt to nickel ratio is generally of the order of 100: 1 in the cobalt sulphate solution derived from the leaching of concentrates, whereas in the latter, it is typically 1 : 10. Thus, in conventional processing, the requirement is either to remove a small amount of nickel from cobalt solutions, or a small amount of cobalt from nickel solutions. Oxidative precipitation processes for cobalt removal from nickel solutions, much like is the case for solvent extraction and ion exchange processes, require precise monitoring of the pH, especially if significant amounts of cobalt are present.

[0009] For nickel laterite leaching, buildup of iron(lll) in solution may require very expensive, high temperature autoclave operations, and these high temperatures tend to drive reactions towards the formation of less desirable species such as basic iron sulfate and hematite. Current state-of-the-art iron removal practices generally involve only a two- step pH change; wherein, in a first stage, limestone or lime may be used to neutralize free acid and precipitate gypsum and iron as an iron hydroxide. Other metals, such as zinc (Zn), magnesium (Mg), and manganese (Mn), etc., may then be precipitated in a second stage having a pH greater than 9. With these conventional two-stage impurity removal processes, low-density/high-surface area ferric hydroxides are formed, which are typically difficult to settle and filter. Moreover, with these conventional two-stage iron removal processes, metal values still in solution along with the precipitates are typically disposed of as tails and are rarely recovered.

[0010] Acid digestion of laterites with sulfuric acid may be used to dissolve all constituents except silica. Aluminum sulfate, ferric sulfate, titanyl sulfate, and magnesium sulfate remain in solution at approximately 90°C. Hot filtration separates silica and any calcium content from the solution. Subsequent exposure of the solution to metallic iron reduces ferric sulfate to ferrous sulfate. For laterite ores it is desirable, even necessary, that the Mn/Mg be separated out from Ni/Co by first precipitating the Ni/Co from solution, and then releaching. A large amount of gypsum is typically formed along with the mixed Ni-Co hydroxide precipitate (MHP) when slaked lime is used as the precipitant for Ni and Co. Nickel and cobalt may be separated from an aluminium- and iron-free acidic nickel laterite leach solution by subjecting the leach solution to extraction with an oxime at a pH in the range of 4 to 5.5 and at a temperature of less than 100°C.

[0011] In order to address extensive leaching times, typically required for high nickel and cobalt value recovery from laterites, and higher capital and operating expenses, the use of a leaching solution consisting of a sulfuric acid/urea mixture has been proposed (WO 2014/037336). It was surmised that the addition of urea improves the dissolution rates of both the nickel and cobalt values.

[0012] A process for the recovery of nickel and/or cobalt values from iron-rich containing sulfate solutions, wherein a substantial proportion of the iron is in the ferrous state has also been proposed (WO 2009/114903). The precipitation behavior of ferrous ions is similar to that of nickel and cobalt ions. This implies that for iron/nickel separation purposes, the precipitation of ferrous ions may cause significant nickel and cobalt losses. The co-precipitation of nickel, cobalt and ferrous ions further occasions higher consumption of neutralizer reagent such as limestone, lime, magnesium carbonate, MgO, soda ash or caustic soda. To remedy this problem, the ferrous iron (Fe ²⁺ ) is oxidized to ferric iron (Fe ³⁺ ) and precipitated as a ferric hydroxide, ferrihydrite, goethite or paragoethite. The nickel and/or cobalt values are subsequently recovered from the iron depleted solution.

[0013] A novel process for the extraction and recovery of nickel, cobalt, manganese and magnesium from a laterite feedstock in high yield and purity, that is of an environmentally cleaner design, and overcoming the technical and economic limitations of the existing commercial processes is of commercial interest.

SUMMARY

[0014] The present disclosure broadly relates to a process for the extraction and recovery of nickel, cobalt, manganese, and magnesium from laterite feedstocks. In an aspect of the present disclosure, the process for the extraction and recovery of nickel, cobalt, manganese, and magnesium from laterite feedstocks comprises an ultrasound assisted extraction step. In a further aspect of the present disclosure, the process for the extraction and recovery of nickel, cobalt, manganese, and magnesium from laterite feedstocks comprises leaching a laterite feedstock in an acidic solution while simultaneously sonicating the acidic solution. In a further aspect of the present disclosure, the process for the extraction and recovery of nickel, cobalt, manganese, and magnesium from laterite feedstocks comprises leaching a laterite feedstock with a reductant in an acidic solution while simultaneously sonicating the acidic solution. The present disclosure also relates to a process for the selective extraction/separation of nickel, cobalt, manganese, and magnesium values from the iron values present in the laterite feedstocks.

[0015] In an aspect, the present disclosure relates to a process for recovering nickel, cobalt, manganese and magnesium values from laterite feedstocks, the process comprising: leaching the laterite feedstocks with a reductant in a sulfuric acid solution while simultaneously sonicating the sulfuric acid solution, thereby producing a first pregnant solution; subjecting the first pregnant solution to an iron removal step, thereby producing a second pregnant solution; subjecting the second pregnant solution to a nickel and cobalt recovery step, thereby producing a solution enriched in manganese and magnesium values; removing manganese values from the solution enriched in manganese and magnesium values, producing a depleted solution; and precipitating the magnesium values from the depleted solution. In an embodiment, the process further comprises oxidizing any residual ferrous iron (Fe ²⁺ ) in the second pregnant solution to ferric iron (Fe ³⁺ ); and subjecting the second pregnant solution to a second iron removal step prior to the nickel and cobalt recovery step. In an embodiment, the process further comprises subjecting the second pregnant solution to a second nickel and cobalt recovery step, thereby producing a solution further enriched in manganese and magnesium values. In an embodiment of the present disclosure, the reductant is a sulfite or bisulfite salt. In a further embodiment of the present disclosure, the sulfite or bisulfite salt is at least one of sodium (Na ⁺ ) or potassium (K ⁺ ). In an embodiment of the present disclosure, the oxidation of residual ferrous iron (Fe ²⁺ ) in the second pregnant solution is performed using an aqueous solution of hydrogen peroxide (H2O2). In an embodiment of the present disclosure, the second nickel and cobalt recovery step comprises further raising the pH of the second pregnant solution between about 7.8 and about 8.2. In an embodiment of the present disclosure, the sonication is performed at a frequency ranging from about 20 to about 200 kHz and an amplitude ranging from 1 % to 100%. In a further embodiment of the present disclosure, the sonication is performed using an external sonication probe. In a further embodiment of the present disclosure, the sonication is performed by conducting the laterite and reductant laden sulfuric acid solution through an external sonicator. In a further embodiment of the present disclosure, the residence time of the laterite and reductant laden sulfuric acid solution in the sonicator ranges between about 1 to about 10 seconds. In a further embodiment of the present disclosure at least two sonicators are used, wherein the at least two sonicators are arranged in a series or parallel arrangement. In a further embodiment of the present disclosure, the sonication is performed using an internal sonication probe.

[0016] In an aspect, the present disclosure relates to a process for recovering nickel, cobalt, manganese and magnesium values from laterite feedstocks, the process comprising: leaching the laterite feedstocks with a reductant in a sulfuric acid solution thereby producing a first pregnant solution; subjecting the first pregnant solution to an iron removal step, thereby producing a second pregnant solution; subjecting the second pregnant solution to a nickel and cobalt recovery step, thereby producing a solution enriched in manganese and magnesium values; removing manganese values from the solution enriched in manganese and magnesium values, producing a depleted solution; and precipitating the magnesium values from the depleted solution. In an embodiment, the process further comprises simultaneously sonicating the acidic solution while leaching the laterite feedstocks. In an embodiment, the process further comprises oxidizing any residual ferrous iron (Fe ²⁺ ) in the second pregnant solution to ferric iron (Fe ³⁺ ); and subjecting the second pregnant solution to a second iron removal step prior to the nickel and cobalt recovery step. In an embodiment, the process further comprises subjecting the second pregnant solution to a second nickel and cobalt recovery step, thereby producing a solution further enriched in manganese and magnesium values. In an embodiment of the present disclosure, the reductant is a sulfite or bisulfite salt. In a further embodiment of the present disclosure, the sulfite or bisulfite salt is at least one of sodium (Na ⁺ ) or potassium (K ⁺ ). In an embodiment of the present disclosure, the oxidation of residual ferrous iron (Fe ²⁺ ) in the second pregnant solution is performed using an aqueous solution of hydrogen peroxide (H2O2). In an embodiment of the present disclosure, the second nickel and cobalt recovery step comprises further raising the pH of the second pregnant solution between about 7.8 and about 8.2. In an embodiment of the present disclosure, the sonication is performed at a frequency ranging from about 20 to about 200 kHz and an amplitude ranging from 1 % to 100%. In a further embodiment of the present disclosure, the sonication is performed using an external sonication probe. In a further embodiment of the present disclosure, the sonication is performed by conducting the laterite and reductant laden sulfuric acid solution through an external sonicator. In a further embodiment of the present disclosure, the residence time of the laterite and reductant laden sulfuric acid solution in the sonicator ranges between about 1 to about 10 seconds. In a further embodiment of the present disclosure at least two sonicators are used, wherein the at least two sonicators are arranged in a series or parallel arrangement. In a further embodiment of the present disclosure, the sonication is performed using an internal sonication probe.

[0017] In an aspect, the present disclosure relates to a process for recovering nickel, cobalt, manganese and magnesium values from laterite feedstocks, the process comprising: leaching the laterite feedstocks with a reductant into sulfuric acid while simultaneously sonicating the sulfuric acid solution, thereby producing a first pregnant solution; subjecting the first pregnant solution to an iron removal step, thereby producing a second pregnant solution; and removing nickel and cobalt values from the second pregnant solution thereby producing a solution enriched in manganese and magnesium values. In an embodiment, the process further comprises the steps of removing the manganese values from the solution enriched in manganese and magnesium values producing a depleted solution; and precipitating the magnesium values from the depleted solution. In an embodiment, the process further comprises oxidizing any residual ferrous iron (Fe ²⁺ ) in the second pregnant solution to ferric iron (Fe ³⁺ ); and subjecting the second pregnant solution to a second iron removal step prior to the nickel and cobalt recovery step. In an embodiment, the process further comprises subjecting the second pregnant solution to a second nickel and cobalt recovery step, thereby producing a solution further enriched in manganese and magnesium values. In an embodiment of the present disclosure, the reductant is a sulfite or bisulfite salt. In a further embodiment of the present disclosure, the sulfite or bisulfite salt is at least one of sodium (Na ⁺ ) or potassium (K ⁺ ). In an embodiment of the present disclosure, the oxidation of residual ferrous iron (Fe ²⁺ ) in the second pregnant solution is performed using an aqueous solution of hydrogen peroxide (H2O2). In an embodiment of the present disclosure, the second nickel and cobalt recovery step comprises further raising the pH of the second pregnant solution between about 7.8 and about 8.2. In an embodiment of the present disclosure, the sonication is performed at a frequency ranging from about 20 to about 200 kHz and an amplitude ranging from 1 % to 100%. In a further embodiment of the present disclosure, the sonication is performed using an external sonication probe. In a further embodiment of the present disclosure, the sonication is performed by conducting the laterite and reductant laden sulfuric acid solution through an external sonicator. In a further embodiment of the present disclosure, the residence time of the laterite and reductant laden sulfuric acid solution in the sonicator ranges between about 1 to about 10 seconds. In a further embodiment of the present disclosure at least two sonicators are used, wherein the at least two sonicators are arranged in a series or parallel arrangement. In a further embodiment of the present disclosure, the sonication is performed using an internal sonication probe.

[0018] In an aspect of the present disclosure, the leaching/sonication of the laterite feedstock may be repeated at least a second time, at the same or a different sonication frequency, acid concentration, amplitude and/or temperature.

[0019] Also disclosed in the context of the present disclosure are embodiments 1 to 272. Embodiment 1 is a process for recovering nickel, cobalt, manganese and magnesium values from a laterite feedstock, the process comprising: leaching the laterite feedstock with a reductant in a sulfuric acid solution while simultaneously sonicating the sulfuric acid solution, thereby producing a first pregnant solution; subjecting the first pregnant solution to an iron removal step, thereby producing a second pregnant solution; subjecting the second pregnant solution to a nickel and cobalt recovery step, thereby producing a solution enriched in manganese and magnesium values; removing manganese values from the solution enriched in manganese and magnesium values, producing a depleted solution; and precipitating the magnesium values from the depleted solution. Embodiment 2 is the process of embodiment 1 , wherein the reductant is a sulfite or bisulfite salt. Embodiment 3 is the process of embodiment 2, wherein the sulfite or bisulfite salt is at least one of a sodium (Na ⁺ ) or potassium (K ⁺ ) salt. Embodiment 4 is the process of any one of embodiments 1 to 3, wherein the reductant comprises a mass percentage from about 0.1 kg/t to about 0.3 kg/t. Embodiment 5 is the process of any one of embodiments 1 to 4, wherein the sulfuric acid leaching comprises using an aqueous solution of sulfuric acid having a mass percentage from about 5 wt.% H2SO4 to about 100 wt.% H2SO4. Embodiment 6 is the process of embodiment 5, wherein the aqueous solution of sulfuric acid has a mass percentage from about 15 wt.% H2SO4 to about 80 wt.% H2SO4. Embodiment 7 is the process of embodiment 5 or 6, wherein the aqueous solution of sulfuric acid has a mass percentage of about 30 wt.% H2SO4. Embodiment 8 is the process of embodiment 5, wherein the aqueous solution of sulfuric acid has a concentration of about 3.5 M. Embodiment 9 is the process of any one of embodiments 1 to 8, wherein the laterite feedstock is ground to a particle size of less than about 0.500 millimeter. Embodiment 10 is the process of embodiment 9, wherein the laterite feedstock is ground to a particle size of less than about 0.125 millimeter. Embodiment 11 is the process of embodiment 9 or 10, wherein the laterite feedstock is ground to a particle size of 75 mm (Pso) or less. Embodiment 12 is the process of any one of embodiments 1 to 11 , wherein the laterite feedstock is dried prior to being processed to remove residual moisture. Embodiment 13 is the process of any one of embodiments 1 to 12, wherein the sulfuric acid leaching is performed at temperatures ranging from about 20°C to about 100°C. Embodiment 14 is the process of embodiment 13, wherein the sulfuric acid leaching is performed at temperatures ranging from about 50°C to about 99°C. Embodiment 15 is the process of embodiment 13 or 14, wherein the sulfuric acid leaching is performed at a temperature of about 95°C. Embodiment 16 is the process of embodiment 1 , wherein the sulfuric acid leaching is performed with a solution of sulfuric acid (L) and a mass of laterite feedstocks (S) having a S to L ratio not exceeding 35 % (35:100 or 35 w/v). Embodiment 17 is the process of embodiment 16, wherein the mass ratio (S-to-L) is not exceeding one to one (1 :1 or 1 kg/kg). Embodiment 18 is the process of embodiment 1 , wherein the sulfuric acid leaching is performed over a period ranging from about 1 hour to about 3 hours. Embodiment 19 is the process of embodiment 18, wherein the sulfuric acid leaching is performed over a period ranging from about 1 .5 hours to about 2.5 hours. Embodiment 20 is the process of embodiment 18 or 19, wherein the sulfuric acid leaching is performed over a period of about 2 hours. Embodiment 21 is the process of embodiment 1 , wherein the sulfuric acid leaching is performed batch wise. Embodiment 22 is the process of embodiment 1 , wherein the sulfuric acid leaching is performed semi-continuously or continuously. Embodiment 23 is the process of any one of embodiments 1 to 22, wherein the iron removal step comprises raising the pH of the first pregnant solution to between about 2.0 and about 3.5. Embodiment 24 is the process of embodiment 23, wherein the pH of the first pregnant solution is raised to about 2.5. Embodiment 25 is the process of embodiment 23 or 24, wherein the iron removal step is performed at a temperature ranging from about 50°C to about 99°C. Embodiment 26 is the process of embodiment 25, wherein the iron removal step is performed at a temperature of about 90°C. Embodiment 27 is the process of any one of embodiments 23 to 26, wherein the iron removal step is performed over a period ranging from about 1 hour to about 3 hours. Embodiment 28 is the process of embodiment 27, wherein the iron removal step is performed over a period of about 2 hours. Embodiment 29 is the process of any one of embodiments 23 to 28, wherein the pH of the first pregnant solution is raised by the addition of a CaCCh slurry. Embodiment 30 is the process of embodiment 29, wherein the CaCCh slurry has a mass percentage (w/w) ranging from about 20% w/w to about 30% w/w. Embodiment 31 is the process of embodiment 30, wherein the CaCCh slurry has a mass percentage (w/w) of about 25% w/w. Embodiment 32 is the process of any one of embodiments 1 to 31 , wherein the nickel and cobalt recovery step comprises raising the pH of the second pregnant solution to between about 7.0 and about 7.5. Embodiment 33 is the process of embodiment 32, wherein the pH of the second pregnant solution is raised to between about 7.0 and about 7.2. Embodiment 34 is the process of embodiment 32 or 33, wherein the pH of the second pregnant solution is raised to about 7.0. Embodiment 35 is the process of any one of embodiments 32 to 34, wherein the nickel and cobalt recovery step is performed at a temperature ranging from about 25°C to about 70°C. Embodiment 36 is the process of embodiment 35, wherein the nickel and cobalt recovery step is performed at a temperature of about 50°C. Embodiment 37 is the process of any one of embodiments 32 to 36, wherein the nickel and cobalt recovery step is performed over a period ranging from about 0.5 hours to about 1 .5 hours. Embodiment 38 is the process of embodiment 37, wherein the nickel and cobalt recovery step is performed over a period of about 1 hour. Embodiment 39 is the process of any one of embodiments 32 to 38, wherein the pH of the second pregnant solution is raised by the addition of a MgO slurry. Embodiment 40 is the process of embodiment 39, wherein the MgO slurry has a mass percentage (w/w) ranging from about 5% w/w to about 15% w/w. Embodiment 41 is the process of embodiment 40, wherein the MgO slurry has a mass percentage (w/w) of about 10% w/w. Embodiment 42 is the process of any one of embodiments 1 to 41 , wherein the step of removing manganese values comprises raising the pH of the solution enriched in manganese and magnesium values to between about 8.5 and about 9.0. Embodiment 43 is the process of embodiment 42, wherein the pH of the solution enriched in manganese and magnesium values is raised to about 9.0. Embodiment 44 is the process of embodiment 42 or 43, wherein the manganese recovery step is performed at a temperature ranging from about 25°C to about 70°C. Embodiment 45 is the process of embodiment 44, wherein the manganese recovery step is performed at a temperature of about 60°C. Embodiment 46 is the process of any one of embodiments 42 to 45, wherein the manganese recovery step is performed over a period ranging from about 0.5 hours to about 1.5 hours. Embodiment 47 is the process of embodiment 46, wherein the manganese recovery step is performed over a period of about 1 hour. Embodiment 48 is the process of any one of embodiments 42 to 47, wherein the pH of the solution enriched in manganese and magnesium values is raised by the addition of a MgO slurry. Embodiment 49 is the process of embodiment 48, wherein the MgO slurry has a mass percentage (w/w) ranging from about 15% w/w to about 25% w/w. Embodiment 50 is the process of embodiment 49, wherein the MgO slurry has a mass percentage (w/w) of about 20% w/w. Embodiment 51 is the process of any one of embodiments 1 to 50, wherein the magnesium values are precipitated by concentrating the depleted solution followed by cooling. Embodiment 52 is the process of embodiment 51 , wherein the magnesium values are recovered as a MgSO4 hydrate. Embodiment 53 is the process of any one of embodiments 1 to 52, further comprising: oxidizing any residual ferrous iron (Fe ²⁺ ) in the second pregnant solution to ferric iron (Fe ³⁺ ); and subjecting the second pregnant solution to a second iron removal step prior to the nickel and cobalt recovery step. Embodiment 54 is the process of embodiment 53, wherein the oxidation is performed using an aqueous solution of hydrogen peroxide (H2O2). Embodiment 55 is the process of embodiment 54, wherein the aqueous H2O2 solution has a mass percentage (w/w) of about 50% w/w. Embodiment 56 is the process of any one of embodiments 53 to 55, wherein the second iron removal step comprises raising the pH of the second pregnant solution to between about 3.5 and about 4.5. Embodiment 57 is the process of embodiment 56, wherein the pH is raised to about 3.5. Embodiment 58 is the process of any one of embodiments 53 to 57, wherein the second iron removal step is performed at a temperature ranging from about 25°C to about 70°C. Embodiment 59 is the process of embodiment 58, wherein the second iron removal step is performed at a temperature of about 70°C. Embodiment 60 is the process of any one of embodiments 53 to 59, wherein the second iron removal step is performed over a period ranging from about 0.5 hours to about 1.5 hours. Embodiment 61 is the process of embodiment 60, wherein the second iron removal step is performed over a period of about 1 hour. Embodiment 62 is the process of any one of embodiments 53 to 61 , wherein the pH of the second pregnant solution resulting from the first iron removal step is raised by the addition of a CaCCh slurry. Embodiment 63 is the process of embodiment 62, wherein the CaCCh slurry has a mass percentage (w/w) ranging from about 10% w/w to about 15% w/w. Embodiment 64 is the process of embodiment 63, wherein the CaCCh slurry has a mass percentage (w/w) of about 12.5% w/w. Embodiment 65 is the process of any one of embodiments 1 to 64, further comprising: subjecting the second pregnant solution to a second nickel and cobalt recovery step, thereby producing a solution further enriched in manganese and magnesium values. Embodiment 66 is the process of embodiment 65, wherein the second nickel and cobalt recovery step comprises further raising the pH of the second pregnant solution to between about 7.8 and about 8.2. Embodiment 67 is the process of embodiment 66, wherein the pH is raised to about 8.0. Embodiment 68 is the process of any one of embodiments 65 to 67, wherein the second nickel and cobalt recovery step is performed at a temperature ranging from about 25°C to about 70°C. Embodiment 69 is the process of embodiment 68, wherein the second nickel and cobalt recovery step is performed at a temperature of about 60°C. Embodiment 70 is the process of any one of embodiments 65 to 69, wherein the second nickel and cobalt recovery step is performed over a period ranging from about 0.5 hours to about 1.5 hours. Embodiment 71 is the process of embodiment 70, wherein the second nickel and cobalt recovery step is performed over a period of about 1 hour. Embodiment 72 is the process of any one of embodiments 65 to 71 , wherein the pH of the second pregnant solution is raised by the addition of a MgO slurry. Embodiment 73 is the process of embodiment 72, wherein the MgO slurry has a mass percentage (w/w) ranging from about 15% w/w to about 25% w/w. Embodiment 74 is the process of embodiment 73, wherein the MgO slurry has a mass percentage (w/w) of about 20% w/w. Embodiment 75 is the process of any one of embodiments 65 to 74, wherein the precipitate resulting from the second nickel and cobalt recovery step is recycled to the first pregnant solution. Embodiment 76 is the process of any one of embodiments 1 to 22, wherein the iron removal step comprises raising the pH of the first pregnant solution between about 2.5 and about 4.5 to produce an iron hydroxide precipitate. Embodiment 77 is the process of embodiment 76, wherein the pH of the first pregnant solution is raised to about 3.0. Embodiment 78 is the process of embodiment 76 or 77, wherein the iron removal step is performed at a temperature ranging from about 20°C to about 50°C. Embodiment 79 is the process of embodiment 78, wherein the iron removal step is performed at a temperature of about 20°C. Embodiment 80 is the process of any one of embodiments 76 to 79, wherein the iron removal step is performed over a period ranging from about 1 hour to about 3 hours. Embodiment 81 is the process of embodiment 80, wherein the iron removal step is performed over a period of about 2 hours. Embodiment 82 is the process of any one of embodiments 76 to 81 , wherein the pH of the first pregnant solution is raised by the addition of an aqueous NH4OH solution. Embodiment 83 is the process of embodiment 82, wherein the aqueous NH4OH solution has a mass percentage (w/w) ranging from about 1 % w/w to about 10% w/w. Embodiment 84 is the process of embodiment 83, wherein the aqueous NH4OH solution has a mass percentage (w/w) ranging from about 5.8% w/w to about 6.0% w/w. Embodiment 85 is the process of any one of embodiments 1 to 84, wherein the sonication is performed at a frequency ranging from about 20 to about 200 kHz and an amplitude ranging from 1 % to 100%. Embodiment 86 is the process of any one of embodiments 1 to 85, wherein the sonication is performed using an external sonication probe. Embodiment 87 is the process of embodiment 86, wherein the sonication is performed by conducting the laterite and reductant laden sulfuric acid solution through an external sonicator. Embodiment 88 is the process of embodiment 87, wherein the residence time of the laterite and reductant laden sulfuric acid solution in the sonicator ranges between about 1 to about 10 seconds. Embodiment 89 is the process of any one of embodiments 86 to 88, wherein at least two sonicators are used, and wherein the at least two sonicators are arranged in a series or parallel arrangement. Embodiment 90 is the process of any one of embodiments 1 to 85, wherein the sonication is performed using an internal sonication probe.

[0020] Embodiment 91 is a process for recovering nickel, cobalt, manganese and magnesium values from a laterite feedstock, the process comprising: leaching the laterite feedstock with a reductant in a sulfuric acid solution thereby producing a first pregnant solution; subjecting the first pregnant solution to an iron removal step, thereby producing a second pregnant solution; subjecting the second pregnant solution to a nickel and cobalt recovery step, thereby producing a solution enriched in manganese and magnesium values; removing manganese values from the solution enriched in manganese and magnesium values, producing a depleted solution; and precipitating the magnesium values from the depleted solution. Embodiment 92 is the process of embodiment 91 , wherein the leaching is performed while simultaneously sonicating the acidic solution. Embodiment 93 is the process of embodiment 91 or 92, wherein the reductant is a sulfite or bisulfite salt. Embodiment 94 is the process of any one of embodiments 91 to 93, wherein the sulfite or bisulfite salt is at least one of a sodium (Na ⁺ ) or potassium (K ⁺ ) salt. Embodiment 95 is the process of any one of embodiments 91 to 94, wherein the reductant comprises a mass percentage from about 0.1 kg/t to about 0.3 kg/t. Embodiment 96 is the process of any one of embodiments 91 to 95, wherein the sulfuric acid leaching comprises using an aqueous solution of sulfuric acid having a mass percentage from about 5 wt.% H2SO4 to about 100 wt.% H2SO4. Embodiment 97 is the process of embodiment 96, wherein the aqueous solution of sulfuric acid has a mass percentage from about 15 wt.% H2SO4 to about 80 wt.% H2SO4. Embodiment 98 is the process of embodiment 96 or 97, wherein the aqueous solution of sulfuric acid has a mass percentage of about 30 wt.% H2SO4. Embodiment 99 is the process of embodiment 96, wherein the aqueous solution of sulfuric acid has a concentration of about 3.5 M. Embodiment 100 is the process of any one of embodiments 91 to 99, wherein the laterite feedstock is ground to a particle size of less than about 0.500 millimeter. Embodiment 101 is the process of embodiment 100, wherein the laterite feedstock is ground to a particle size of less than about 0.125 millimeter. Embodiment 102 is the process of embodiment 100 or 101 , wherein the laterite feedstock is ground to a particle size of 75 mm (Pso) or less. Embodiment 103 is the process of any one of embodiments 91 to 102, wherein the laterite feedstock is dried prior to being processed to remove residual moisture. Embodiment 104 is the process of any one of embodiments 91 to 103, wherein the sulfuric acid leaching is performed at temperatures ranging from about 20°C to about 100°C. Embodiment 105 is the process of embodiment 104, wherein the sulfuric acid leaching is performed at temperatures ranging from about 50°C to about 99°C. Embodiment 106 is the process of embodiment 92 or 93, wherein the sulfuric acid leaching is performed at a temperature of about 95°C. Embodiment 107 is the process of embodiment 91 or 92, wherein the sulfuric acid leaching is performed with a solution of sulfuric acid (L) and a mass of laterite feedstock (S) having a S to L ratio not exceeding 35 % (35:100 or 35 w/v). Embodiment 108 is the process of embodiment 107, wherein the mass ratio (S-to-L) is not exceeding one to one (1 :1 or 1 kg/kg). Embodiment 109 is the process of embodiment 91 or 92, wherein the sulfuric acid leaching is performed over a period ranging from about 1 hour to about 3 hours. Embodiment 110 is the process of embodiment 109, wherein the sulfuric acid leaching is performed over a period ranging from about 1 .5 hours to about 2.5 hours. Embodiment 111 is the process of embodiment 109 or 110, wherein the sulfuric acid leaching is performed over a period of about 2 hours. Embodiment 112 is the process of embodiment 91 or 92, wherein the sulfuric acid leaching is performed batch wise. Embodiment 113 is the process of embodiment 91 or 92, wherein the sulfuric acid leaching is performed semi-continuously or continuously. Embodiment 114 is the process of any one of embodiments 91 to 113, wherein the iron removal step comprises raising the pH of the first pregnant solution to between about 2.0 and about 3.5. Embodiment 115 is the process of embodiment 114, wherein the pH of the first pregnant solution is raised to about 2.5. Embodiment 116 is the process of embodiment 114 or 115, wherein the iron removal step is performed at a temperature ranging from about 50°C to about 99°C. Embodiment 117 is the process of embodiment 116, wherein the iron removal step is performed at a temperature of about 90°C. Embodiment 118 is the process of any one of embodiments 114 to 117, wherein the iron removal step is performed over a period ranging from about 1 hour to about 3 hours. Embodiment 119 is the process of embodiment 118, wherein the iron removal step is performed over a period of about 2 hours. Embodiment 120 is the process of any one of embodiments 114 to 119, wherein the pH of the first pregnant solution is raised by the addition of a CaCCh slurry. Embodiment 121 is the process of embodiment 120, wherein the CaCCh slurry has a mass percentage (w/w) ranging from about 20% w/w to about 30% w/w. Embodiment 122 is the process of embodiment 121 , wherein the CaCCh slurry has a mass percentage (w/w) of about 25% w/w. Embodiment 123 is the process of any one of embodiments 91 to 122, wherein the nickel and cobalt recovery step comprises raising the pH of the second pregnant solution to between about 7.0 and about 7.5. Embodiment 124 is the process of embodiment 123, wherein the pH of the second pregnant solution is raised to between about 7.0 and about 7.2. Embodiment 125 is the process of embodiment 123 or 124, wherein the pH of the second pregnant solution is raised to about 7.0. Embodiment 126 is the process of any one of embodiments 123 to 125, wherein the nickel and cobalt recovery step is performed at a temperature ranging from about 50°C to about 70°C. Embodiment 127 is the process of embodiment 126, wherein the nickel and cobalt recovery step is performed at a temperature of about 50°C. Embodiment 128 is the process of any one of embodiments 123 to 127, wherein the nickel and cobalt recovery step is performed over a period ranging from about 0.5 hours to about 1.5 hours. Embodiment 129 is the process of embodiment 128, wherein the nickel and cobalt recovery step is performed over a period of about 1 hour. Embodiment 130 is the process of any one of embodiments 123 to 129, wherein the pH of the second pregnant solution is raised by the addition of a MgO slurry. Embodiment 131 is the process of embodiment 130, wherein the MgO slurry has a mass percentage (w/w) ranging from about 5% w/w to about 15% w/w. Embodiment 132 is the process of embodiment 131 , wherein the MgO slurry has a mass percentage (w/w) of about 10% w/w. Embodiment 133 is the process of any one of embodiments 91 to 132, wherein the step of removing manganese values comprises raising the pH of the solution enriched in manganese and magnesium values to between about 8.5 and about 9.0. Embodiment 134 is the process of embodiment 133, wherein the pH of the solution enriched in manganese and magnesium values is raised to about 9.0. Embodiment 135 is the process of embodiment 133 or 134, wherein the manganese recovery step is performed at a temperature ranging from about 25°C to about 70°C. Embodiment 136 is the process of embodiment 135, wherein the manganese recovery step is performed at a temperature of about 60°C. Embodiment 137 is the process of any one of embodiments 133 to 136, wherein the manganese recovery step is performed over a period ranging from about 0.5 hours to about 1.5 hours. Embodiment 138 is the process of embodiment 137, wherein the manganese recovery step is performed over a period of about 1 hour. Embodiment 139 is the process of any one of embodiments 133 to 138, wherein the pH of the solution enriched in manganese and magnesium values is raised by the addition of a MgO slurry. Embodiment 140 is the process of embodiment 139, wherein the MgO slurry has a mass percentage (w/w) ranging from about 15% w/w to about 25% w/w. Embodiment 141 is the process of embodiment 140, wherein the MgO slurry has a mass percentage (w/w) of about 20% w/w. Embodiment 142 is the process of any one of embodiments 91 to 141 , wherein the magnesium values are precipitated by concentrating the depleted solution followed by cooling. Embodiment 143 is the process of embodiment 142, wherein the magnesium values are recovered as a MgSO4 hydrate. Embodiment 144 is the process of any one of embodiments 91 to 143, further comprising: oxidizing any residual ferrous iron (Fe ²⁺ ) in the second pregnant solution to ferric iron (Fe ³⁺ ); and subjecting the second pregnant solution to a second iron removal step prior to the nickel and cobalt recovery step. Embodiment 145 is the process of embodiment 144, wherein the oxidation is performed using an aqueous solution of hydrogen peroxide (H2O2). Embodiment 146 is the process of embodiment 145, wherein the aqueous H2O2 solution has a mass percentage (w/w) of about 50% w/w. Embodiment 147 is the process of any one of embodiments 144 to 146, wherein the second iron removal step comprises raising the pH of the second pregnant solution to between about 3.5 and about 4.5. Embodiment 148 is the process of embodiment 147, wherein the pH is raised to about 3.5. Embodiment 149 is the process of any one of embodiments 144 to 148, wherein the second iron removal step is performed at a temperature ranging from about 25°C to about 70°C. Embodiment 150 is the process of embodiment 149, wherein the second iron removal step is performed at a temperature of about 70°C. Embodiment 151 is the process of any one of embodiments 144 to 150, wherein the second iron removal step is performed over a period ranging from about 0.5 hours to about 1.5 hours. Embodiment 152 is the process of embodiment 151 , wherein the second iron removal step is performed over a period of about 1 hour. Embodiment 153 is the process of any one of embodiments 144 to 152, wherein the pH of the second pregnant solution resulting from the first iron removal step is raised by the addition of a CaCCh slurry. Embodiment 154 is the process of embodiment 153, wherein the CaCCh slurry has a mass percentage (w/w) ranging from about 10% w/w to about 15% w/w. Embodiment 155 is the process of embodiment 154, wherein the CaCCh slurry has a mass percentage (w/w) of about 12.5% w/w. Embodiment 156 is the process of any one of embodiments 91 to 155, further comprising: subjecting the second pregnant solution to a second nickel and cobalt recovery step, thereby producing a solution further enriched in manganese and magnesium values. Embodiment 157 is the process of embodiment 156, wherein the second nickel and cobalt recovery step comprises further raising the pH of the second pregnant solution to between about 7.8 and about 8.2. Embodiment 158 is the process of embodiment 157, wherein the pH is raised to about 8.0. Embodiment 159 is the process of any one of embodiments 156 to 158, wherein the second nickel and cobalt recovery step is performed at a temperature ranging from about 25°C to about 70°C. Embodiment 160 is the process of embodiment 159, wherein the second nickel and cobalt recovery step is performed at a temperature of about 60°C. Embodiment 161 is the process of any one of embodiments 156 to 160, wherein the second nickel and cobalt recovery step is performed over a period ranging from about 0.5 hours to about 1.5 hours. Embodiment 162 is the process of embodiment 161 , wherein the second nickel and cobalt recovery step is performed over a period of about 1 hour. Embodiment 163 is the process of any one of embodiments 156 to 162, wherein the pH of the second pregnant solution is raised by the addition of a MgO slurry. Embodiment 164 is the process of embodiment 163, wherein the MgO slurry has a mass percentage (w/w) ranging from about 15% w/w to about 25% w/w. Embodiment 165 is the process of embodiment 164, wherein the MgO slurry has a mass percentage (w/w) of about 20% w/w. Embodiment 166 is the process of any one of embodiments 156 to 165, wherein the precipitate resulting from the second nickel and cobalt recovery step is recycled to the first pregnant solution. Embodiment 167 is the process of any one of embodiments 91 to 113, wherein the iron removal step comprises raising the pH of the first pregnant solution to between about 2.5 and about 4.5 to produce an iron hydroxide precipitate. Embodiment 168 is the process of embodiment 167, wherein the pH of the first pregnant solution is raised to about 3.0. Embodiment 169 is the process of embodiment 167 or 168, wherein the iron removal step is performed at a temperature ranging from about 20°C to about 50°C. Embodiment 170 is the process of embodiment 169, wherein the iron removal step is performed at a temperature of about 20°C. Embodiment 171 is the process of any one of embodiments 167 to 170, wherein the iron removal step is performed over a period ranging from about 1 hour to about 3 hours. Embodiment 172 is the process of embodiment 171 , wherein the iron removal step is performed over a period of about 2 hours. Embodiment 173 is the process of any one of embodiments 167 to 172, wherein the pH of the first pregnant solution is raised by the addition of an aqueous NH4OH solution. Embodiment 174 is the process of embodiment 173, wherein the aqueous NH4OH solution has a mass percentage (w/w) ranging from about 1 % w/w to about 10% w/w. Embodiment 175 is the process of embodiment 174, wherein the aqueous NH4OH solution has a mass percentage (w/w) ranging from about 5.8% w/w to about 6.0% w/w. Embodiment 176 is the process of embodiment 92, wherein the sonication is performed at a frequency ranging from about 20 to about 200 kHz and an amplitude ranging from 1 % to 100%. Embodiment 177 is the process of embodiment 176, wherein the sonication is performed using an external sonication probe. Embodiment 178 is the process of embodiment 176 or 177, wherein the sonication is performed by conducting the laterite and reductant laden sulfuric acid solution through an external sonicator. Embodiment 179 is the process of embodiment 178, wherein the residence time of the laterite and reductant laden sulfuric acid solution in the sonicator ranges between about 1 to about 10 seconds. Embodiment 180 is the process of any one of embodiments 177 to 179, wherein at least two sonicators are used, and wherein the at least two sonicators are arranged in a series or parallel arrangement. Embodiment 181 is the process of embodiment 92, wherein the sonication is performed using an internal sonication probe.

[0021] Embodiment 182 is a process for recovering nickel and cobalt values from a laterite feedstock, the process comprising: leaching the laterite feedstock with a reductant in a sulfuric acid solution while simultaneously sonicating the sulfuric acid solution, thereby producing a first pregnant solution; subjecting the first pregnant solution to an iron removal step, thereby producing a second pregnant solution; and removing nickel and cobalt values from the second pregnant solution thereby producing a solution enriched in manganese and magnesium values. Embodiment 183 is the process of embodiment 182, further comprising the steps of recovering the manganese values from the solution enriched in manganese and magnesium values producing a depleted solution; and precipitating the magnesium values from the depleted solution. Embodiment 184 is the process of embodiment 182 or 183, wherein the reductant is a sulfite or bisulfite salt. Embodiment 185 is the process of any one of embodiments 182 to 184, wherein the sulfite or bisulfite salt is at least one of a sodium (Na ⁺ ) or potassium (K ⁺ ) salt. Embodiment 186 is the process of any one of embodiments 182 to 185, wherein the reductant comprises a mass percentage from about 0.1 kg/t to about 0.3 kg/t. Embodiment 187 is the process of any one of embodiments 182 to 186, wherein the sulfuric acid leaching comprises using an aqueous solution of sulfuric acid having a mass percentage from about 5 wt.% H2SO4 to about 100 wt.% H2SO4. Embodiment 188 is the process of embodiment 187, wherein the aqueous solution of sulfuric acid has a mass percentage from about 15 wt.% H2SO4 to about 80 wt.% H2SO4. Embodiment 189 is the process of embodiment 187 or 188, wherein the aqueous solution of sulfuric acid has a mass percentage of about 30 wt.% H2SO4. Embodiment 190 is the process of embodiment 187, wherein the aqueous solution of sulfuric acid has a concentration of about 3.5 M. Embodiment 191 is the process of any one of embodiments 182 to 190, wherein the laterite feedstock is ground to a particle size of less than about 0.500 millimeter. Embodiment 192 is the process of embodiment 191 , wherein the laterite feedstock is ground to a particle size of less than about 0.125 millimeter. Embodiment 193 is the process of embodiment 191 or 192, wherein the laterite feedstock is ground to a particle size of 75 mm (Pso) or less. Embodiment 194 is the process of any one of embodiments 182 to 193, wherein the laterite feedstock is dried prior to being processed to remove residual moisture. Embodiment 195 is the process of any one of embodiments 182 to 194, wherein the sulfuric acid leaching is performed at temperatures ranging from about 20°C to about 100°C. Embodiment 196 is the process of embodiment 195, wherein the sulfuric acid leaching is performed at temperatures ranging from about 50°C to about 99°C. Embodiment 197 is the process of embodiment 195 or 196, wherein the sulfuric acid leaching is performed at a temperature of about 95°C. Embodiment 198 is the process of embodiment 182 or 183, wherein the sulfuric acid leaching is performed with a solution of sulfuric acid (L) and a mass of laterite feedstocks (S) having a S to L ratio not exceeding 35 % (35:100 or 35 w/v). Embodiment 199 is the process of embodiment 198, wherein the mass ratio (S-to-L) is not exceeding one to one (1 :1 or 1 kg/kg). Embodiment 200 is the process of embodiment 182 or 183, wherein the sulfuric acid leaching is performed over a period ranging from about 1 hour to about 3 hours. Embodiment 201 is the process of embodiment 200, wherein the sulfuric acid leaching is performed over a period ranging from about 1.5 hours to about 2.5 hours. Embodiment 202 is the process of embodiment 200 or 201 , wherein the sulfuric acid leaching is performed over a period ranging of about 2 hours. Embodiment 203 is the process of embodiment 182 or 183, wherein the sulfuric acid leaching is performed batch wise. Embodiment 204 is the process of embodiment 182 or 183, wherein the sulfuric acid leaching is performed semi-continuously or continuously. Embodiment 205 is the process of any one of embodiments 182 to 204, wherein the iron removal step comprises raising the pH of the first pregnant solution to between about 2.0 and about 3.5. Embodiment 206 is the process of embodiment 205, wherein the pH of the first pregnant solution is raised to about 2.5. Embodiment 207 is the process of embodiment 205 or 206, wherein the iron removal step is performed at a temperature ranging from about 50°C to about 99°C. Embodiment 208 is the process of embodiment 207, wherein the iron removal step is performed at a temperature of about 90°C. Embodiment 209 is the process of any one of embodiments 205 to 208, wherein the iron removal step is performed over a period ranging from about 1 hour to about 3 hours. Embodiment 210 is the process of embodiment 209, wherein the iron removal step is performed over a period of about 2 hours. Embodiment 211 is the process of any one of embodiments 205 to 210, wherein the pH of the first pregnant solution is raised by the addition of a CaCCh slurry. Embodiment 212 is the process of embodiment 211 , wherein the CaCOa slurry has a mass percentage (w/w) ranging from about 20% w/w to about 30% w/w. Embodiment 213 is the process of embodiment 212, wherein the CaCOa slurry has a mass percentage (w/w) of about 25% w/w. Embodiment 214 is the process of any one of embodiments 182 to 213, wherein the nickel and cobalt recovery step comprises raising the pH of the second pregnant solution to between about 7.0 and about 7.5. Embodiment 215 is the process of embodiment 214, wherein the pH of the second pregnant solution is raised to between about 7.0 and about 7.2. Embodiment 216 is the process of embodiment 214 or 215, wherein the pH of the second pregnant solution is raised to about 7.0. Embodiment 217 is the process of any one of embodiments 214 to 216, wherein the nickel and cobalt recovery step is performed at a temperature ranging from about 50°C to about 70°C. Embodiment 218 is the process of embodiment 217, wherein the nickel and cobalt recovery step is performed at a temperature of about 50°C. Embodiment 219 is the process of any one of embodiments 214 to 218, wherein the nickel and cobalt recovery step is performed over a period ranging from about 0.5 hours to about 1 .5 hours. Embodiment 220 is the process of embodiment 219, wherein the nickel and cobalt recovery step is performed over a period of about 1 hour. Embodiment 221 is the process of any one of embodiments 214 to 220, wherein the pH of the second pregnant solution is raised by the addition of a MgO slurry. Embodiment 222 is the process of embodiment 221 , wherein the MgO slurry has a mass percentage (w/w) ranging from about 5% w/w to about 15% w/w. Embodiment 223 is the process of embodiment 222, wherein the MgO slurry has a mass percentage (w/w) of about 10% w/w. Embodiment 224 is the process of embodiment 183, wherein the step of recovering the manganese values comprises raising the pH of the solution enriched in manganese and magnesium values to between about 8.5 and about 9.0. Embodiment 225 is the process of embodiment 224, wherein the pH of the solution enriched in manganese and magnesium values is raised to about 9.0. Embodiment 226 is the process of embodiment 224 or 225, wherein the manganese recovery step is performed at a temperature ranging from about 25°C to about 70°C. Embodiment 227 is the process of embodiment 226, wherein the manganese recovery step is performed at a temperature of about 60°C. Embodiment 228 is the process of any one of embodiments 224 to 227, wherein the manganese recovery step is performed over a period ranging from about 0.5 hours to about 1.5 hours. Embodiment 229 is the process of embodiment 228, wherein the manganese recovery step is performed over a period of about 1 hour. Embodiment 230 is the process of any one of embodiments 224 to 229, wherein the pH of the solution enriched in manganese and magnesium values is raised by the addition of a MgO slurry. Embodiment 231 is the process of embodiment 230, wherein the MgO slurry has a mass percentage (w/w) ranging from about 15% w/w to about 25% w/w. Embodiment 232 is the process of embodiment 231 , wherein the MgO slurry has a mass percentage (w/w) of about 20% w/w. Embodiment 233 is the process of any one of embodiments 224 to 232, wherein the magnesium values are precipitated by concentrating the depleted solution followed by cooling. Embodiment 234 is the process of embodiment 233, wherein the magnesium values are recovered as a MgSC>4 hydrate. Embodiment 235 is the process of any one of embodiments 182 to 234, further comprising: oxidizing any residual ferrous iron (Fe ²⁺ ) in the second pregnant solution to ferric iron (Fe ³⁺ ); and subjecting the second pregnant solution to a second iron removal step prior to the nickel and cobalt recovery step. Embodiment 236 is the process of embodiment 235, wherein the oxidation is performed using an aqueous solution of hydrogen peroxide (H2O2). Embodiment 237 is the process of embodiment 236, wherein the aqueous H2O2 solution has a mass percentage (w/w) of about 50% w/w. Embodiment 238 is the process of any one of embodiments 235 to 237, wherein the second iron removal step comprises raising the pH of the second pregnant solution between about 3.5 and about 4.5. Embodiment 239 is the process of embodiment 238, wherein the pH is raised to about 3.5. Embodiment 240 is the process of any one of embodiments 235 to 239, wherein the second iron removal step is performed at a temperature ranging from about 25°C to about 70°C. Embodiment 241 is the process of embodiment 240, wherein the second iron removal step is performed at a temperature of about 70°C. Embodiment 242 is the process of any one of embodiments 235 to 241 , wherein the second iron removal step is performed over a period ranging from about 0.5 hours to about 1 .5 hours. Embodiment 243 is the process of embodiment 242, wherein the second iron removal step is performed over a period of about 1 hour. Embodiment 244 is the process of any one of embodiments 235 to 243, wherein the pH of the second pregnant solution resulting from the first iron removal step is raised by the addition of a CaCCh slurry. Embodiment 245 is the process of embodiment 244, wherein the CaCCh slurry has a mass percentage (w/w) ranging from about 10% w/w to about 15% w/w. Embodiment 246 is the process of embodiment 245, wherein the CaCCh slurry has a mass percentage (w/w) of about 12.5% w/w. Embodiment 247 is the process of any one of embodiments 182 to 246, further comprising: subjecting the second pregnant solution to a second nickel and cobalt recovery step, thereby producing a solution further enriched in manganese and magnesium values. Embodiment 248 is the process of embodiment 247, wherein the second nickel and cobalt recovery step comprises raising the pH of the second pregnant solution to between about 7.8 and about 8.2. Embodiment 249 is the process of embodiment 248, wherein the pH is raised to about 8.0. Embodiment 250 is the process of any one of embodiments 247 to 249, wherein the second nickel and cobalt recovery step is performed at a temperature ranging from about 25°C to about 70°C. Embodiment 251 is the process of embodiment 250, wherein the second nickel and cobalt recovery step is performed at a temperature of about 60°C. Embodiment 252 is the process of any one of embodiments 247 to 251 , wherein the second nickel and cobalt recovery step is performed over a period ranging from about 0.5 hours to about 1 .5 hours. Embodiment 253 is the process of embodiment 252, wherein the second nickel and cobalt recovery step is performed over a period of about 1 hour. Embodiment 254 is the process of any one of embodiments 248 to 253, wherein the pH of the second pregnant solution is raised by the addition of a MgO slurry. Embodiment 255 is the process of embodiment 254, wherein the MgO slurry has a mass percentage (w/w) ranging from about 15% w/w to about 25% w/w. Embodiment 256 is the process of embodiment 255, wherein the MgO slurry has a mass percentage (w/w) of about 20% w/w. Embodiment 257 is the process of any one of embodiments 247 to 256, wherein the precipitate resulting from the second nickel and cobalt recovery step is recycled to the first pregnant solution. Embodiment 258 is the process of any one of embodiments 182 to 204, wherein the iron removal step comprises raising the pH of the first pregnant solution between about 2.5 and about 4.5 to produce an iron hydroxide precipitate. Embodiment 259 is the process of embodiment 258, wherein the pH of the first pregnant solution is raised to about 3.0. Embodiment 260 is the process of embodiment 258 or 259, wherein the iron removal step is performed at a temperature ranging from about 20°C to about 50°C. Embodiment 261 is the process of embodiment 260, wherein the iron removal step is performed at a temperature of about 20°C. Embodiment 262 is the process of any one of embodiments 258 to 261 , wherein the iron removal step is performed over a period ranging from about 1 hour to about 3 hours. Embodiment 263 is the process of embodiment 262, wherein the iron removal step is performed over a period of about 2 hours. Embodiment 264 is the process of any one of embodiments 258 to 263, wherein the pH of the first pregnant solution is raised by the addition of an aqueous NH4OH solution. Embodiment 265 is the process of embodiment 264, wherein the aqueous NH4OH solution has a mass percentage (w/w) ranging from about 1 % w/w to about 10% w/w. Embodiment 266 is process of embodiment 265, wherein the aqueous NH4OH solution has a mass percentage (w/w) ranging from about 5.8% w/w to about 6.0% w/w. Embodiment 267 is the process of any one of embodiments 182 to 266, wherein the sonication is performed at a frequency ranging from about 20 to about 200 kHz and an amplitude ranging from 1 % to 100%. Embodiment 268 is the process of any one of embodiments 182 to 267, wherein the sonication is performed using an external sonication probe. Embodiment 269 is the process of embodiment 268, wherein the sonication is performed by conducting the laterite and reductant laden sulfuric acid solution through an external sonicator. Embodiment 270 is the process of embodiment 269, wherein the residence time of the laterite and reductant laden sulfuric acid solution in the sonicator ranges between about 1 to about 10 seconds. Embodiment 271 is the process of any one of embodiments 268 to 270, wherein at least two sonicators are used, and wherein the at least two sonicators are arranged in a series or parallel arrangement. Embodiment 272 is the process of any one of embodiments 182 to 267, wherein the sonication is performed using an internal sonication probe.

[0022] The word “a” or “an” when used in conjunction with the term “comprising” in the claims and/or the specification may mean “one”, but it is also consistent with the meaning of “one or more”, “at least one”, and “one or more than one” unless the content clearly dictates otherwise. Similarly, the word “another” may mean at least a second or more unless the content clearly dictates otherwise.

[0023] As used in this specification and claim(s), the words “comprising” (and any form of comprising, such as “comprise” and “comprises”), “having” (and any form of having, such as “have” and “has”), “including” (and any form of including, such as “include” and “includes”) or “containing” (and any form of containing, such as “contain” and “contains”), are inclusive or open-ended and do not exclude additional, unrecited elements or process steps.

[0024] As used in this specification and claim(s), the word “consisting” and its derivatives, are intended to be close ended terms that specify the presence of stated features, elements, components, groups, integers, and/or steps, and also exclude the presence of other unstated features, elements, components, groups, integers and/or steps.

[0025] The term “consisting essentially of”, as used herein, is intended to specify the presence of the stated features, elements, components, groups, integers, and/or steps as well as those that do not materially affect the basic and novel characteristic(s) of these features, elements, components, groups, integers, and/or steps.

[0026] The terms “about”, “substantially” and “approximately” as used herein mean a reasonable amount of deviation of the modified term such that the end result is not significantly changed. These terms of degree should be construed as including a deviation of at least ±5% of the modified term if this deviation would not negate the meaning of the word it modifies. [0027] The foregoing and other advantages and features of the present disclosure will become more apparent upon reading of the following non-restrictive detailed description of illustrative embodiments thereof, with reference to the accompanying drawings/figures. It should be understood, however, that the detailed description and the illustrative embodiments, while indicating specific embodiments of the disclosure, are given by way of illustration only, since various changes and modifications within the spirit and scope of the disclosure will become apparent to those skilled in the art from this description.

BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES

[0028] The following figures/drawings form part of the present specification and are included to further demonstrate certain aspects of the present specification. The present specification may be better understood by reference to one or more of these figures/drawings in combination with the detailed description. In the appended drawings/figures:

[0029] FIG. 1 - Illustration of a flowchart illustrating the process for the extraction and recovery of nickel, cobalt, manganese and magnesium values from a laterite feedstock, in accordance with an embodiment of the present disclosure. The process comprises leaching the laterite feedstock with a reductant (RR) in a sulfuric acid solution.

[0030] FIG. 2 - Illustration of experimental plots illustrating the effects of the amount of reductant (RR) (A), leaching time (B), and sulfuric acid concentration (C) on the leaching efficiency (% recovery) of selected metal values (/.e., recovery of No, Co and Sc), in accordance with an embodiment of the present disclosure.

[0031] FIG. 3 - Illustration of experimental plots illustrating the precipitation recoveries of: (A) Fe, Al and Cr; and (B) Mn, Co, Ni, V and Sc as a function of pH, at a temperature of 90°C and a precipitation duration of 2 hours, in accordance with an embodiment of the present disclosure.

[0032] FIG. 4 - Illustration of experimental plots illustrating the precipitation recoveries of: (A) Fe, Al and Cr; and (B) Mn, Co, Ni, V and Sc as a function of temperature, at pH = 2.5 and for a precipitation duration of 2 hours, in accordance with an embodiment of the present disclosure.

[0033] FIG. 5 - Illustration of experimental plots illustrating the precipitation recoveries of: (A) Fe, Al and Cr; and (B) Mn, Co, Ni, V and Sc as a function of precipitation duration, at pH = 2.5, and at a temperature of 90°C, in accordance with an embodiment of the present disclosure. [0034] FIG. 6 - Illustration of an experimental plot illustrating the precipitation recoveries of Fe, Al, Cr, Mn, Co and Ni as a function of pH, at a temperature of 70°C and a precipitation duration of 1 hour, in accordance with an embodiment of the present disclosure.

[0035] FIG. 7 - Illustration of an experimental plot illustrating the precipitation recoveries of Fe, Al, Cr, Mn, Co and Ni as a function of temperature, at pH = 3.5 and a precipitation duration of 1 hour, in accordance with an embodiment of the present disclosure.

[0036] FIG. 8 - Illustration of an experimental plot illustrating the precipitation recoveries of Fe, Al, Cr, Mn, Co and Ni as a function of precipitation duration, at pH = 3.5, and a temperature of 70°C, in accordance with an embodiment of the present disclosure.

[0037] FIG. 9 - Illustration of an experimental plot illustrating the precipitation recoveries of Ni, Co and Mn as a function of pH, at a temperature of 50°C and a precipitation duration of 1 hour, in accordance with an embodiment of the present disclosure.

[0038] FIG. 10 - Illustration of an experimental plot illustrating the precipitation recoveries of Ni, Co and Mn as a function of temperature, at pH = 7.0 and a precipitation duration of 1 hour, in accordance with an embodiment of the present disclosure.

[0039] FIG. 11 - Illustration of an experimental plot illustrating the precipitation recoveries of Ni, Co and Mn as a function of precipitation duration, at pH = 7.0, and a temperature of 50°C, in accordance with an embodiment of the present disclosure.

[0040] FIG. 12 - Illustration of an experimental plot illustrating the precipitation recoveries of Ni, Co and Mn as a function of pH, at a temperature of 60°C and a precipitation duration of 1 hour, in accordance with an embodiment of the present disclosure.

[0041] FIG. 13 - Illustration of an experimental plot illustrating the precipitation recoveries of Ni, Co and Mn as a function of temperature, at pH = 8.0 and a precipitation duration of 1 hour, in accordance with an embodiment of the present disclosure.

[0042] FIG. 14 - Illustration of an experimental plot illustrating the precipitation recoveries of Ni, Co and Mn as a function of precipitation duration, at pH = 8.0, and a temperature of 60°C, in accordance with an embodiment of the present disclosure. [0043] FIG. 15 - Illustration of an experimental plot illustrating the precipitation recoveries of Mn as a function of pH, at a temperature of 50°C and a precipitation duration of 1 hour, in accordance with an embodiment of the present disclosure.

[0044] FIG. 16 - Illustration of an experimental plot illustrating the precipitation recoveries of Mn as a function of precipitation duration, at pH = 9.0, and a temperature of 50°C, in accordance with an embodiment of the present disclosure.

[0045] FIG. 17 - Illustration of a flowchart illustrating the process for the extraction and recovery of nickel, cobalt, manganese and magnesium values from a laterite feedstock, in accordance with an embodiment of the present disclosure. The process comprises the use of an external sonicator, and leaching a sonicated feed material with or without a reductant (RR) in a sulfuric acid solution.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0046] The present disclosure relates to a process for the extraction and recovery of nickel, cobalt, manganese, and magnesium from a feedstock, more specifically a laterite feedstock. In an aspect of the present disclosure, the process for the extraction and recovery of nickel, cobalt, manganese and magnesium from a laterite feedstock comprises an ultrasound assisted extraction step. In a further aspect of the present disclosure, the process for the extraction and recovery of nickel, cobalt, manganese, and magnesium comprises leaching a laterite feedstock in an acidic solution while simultaneously sonicating the acidic solution. The present disclosure also relates to a process for the extraction and recovery of nickel, cobalt, manganese and magnesium from a laterite feedstock using flash sonication. As used herein, the term flash sonication is generally associated with the use of an external sonication probe. These and other aspects of the disclosure are described in greater detail below.

[0047] The process for the extraction and recovery of nickel, cobalt, manganese, and magnesium from a laterite feedstock advantageously comprises an ultrasound assisted extraction step providing for the extraction of nickel, cobalt, manganese, and magnesium in high yields.

[0048] In an embodiment of the present disclosure, and with reference to FIG. 1 , the process may be broadly divided into two sections: (1) a first section aimed at providing a Ni-Co MHP (mixed hydroxide precipitate); and (2) a second section aimed at refining the Ni-Co MHP into Ni and Co sulfates at high levels of purity, advantageously battery grade purity. In an embodiment of the present disclosure, the first section comprises an ultrasound assisted extraction (“leaching”) step; an iron removal step; and a Ni-Co precipitation step. In an embodiment of the present disclosure, the second section comprises a manganese removal step; and a magnesium removal step. In a further embodiment of the present disclosure, the first section may advantageously comprise a second iron removal step prior to the Ni-Co precipitation step. In yet a further embodiment of the present disclosure, the first section may advantageously comprise a second Ni-Co precipitation step.

[0049] The composition of various laterite feedstocks obtained from Guatemala, in accordance with an embodiment of the present disclosure, was analyzed and is illustrated in Table 1. The analysis was conducted using Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES). Non-negligible amounts of vanadium (135.4-197.3 mg/kg) and scandium (38.4-63.8 mg/kg) were also found in the samples, which could advantageously be considered for further valorization. The samples as received contained a moisture content ranging from 40-90%. Prior to being processed, the samples were dried and crushed.

[0050] Table 1 : Composition (wt. %) of Guatemala laterite feedstocks.

[0051] In an embodiment of the present disclosure, and with reference to FIG. 1 , a sample of laterite feedstock (interchangeably referred herein as an ore sample) is subjected to atmospheric leaching at 95°C in a reactor using H2SO4. A small amount of a reductant (RR) may advantageously be added to enhance nickel and other metal values extraction. The resulting pregnant leach solution (PLS) was then partially neutralized by the addition of calcium carbonate (CaCCh) resulting in the precipitation of the iron, aluminum, and chromium values, referred to as the first iron removal step. The precipitation procedure may advantageously be repeated a second time, referred to as the second iron removal step. In addition to removing residual iron from the pregnant leach solution, the second iron removal step advantageously further reduces any residual aluminum and chromium content. The resulting precipitates may be isolated by vacuum filtration followed by drying. The remaining pregnant solution was then treated with magnesium oxide (MgO) to provide a Ni-Co MHP (mixed hydroxide precipitate) which may be isolated by vacuum filtration followed by drying, referred to as the first Ni-Co precipitation step. The resulting pregnant solution may advantageously be treated with further magnesium oxide (MgO) to provide additional Ni-Co MHP, which may be isolated by vacuum filtration followed by drying, referred to as the second Ni-Co precipitation step. In an embodiment of the present disclosure, the second Ni-Co MHP may advantageously by recycled into the leaching process to improve nickel recovery. The remaining solution was then subjected to a manganese precipitation step by means of the addition of further magnesium oxide (MgO). The manganese precipitation step may be advantageously performed by raising the pH of the solution to about 8.5 and about 9.0. The filtrate may be isolated by vacuum filtration followed by drying. The remaining solution is then subjected to a magnesium recovery step, advantageously performed by concentrating the remaining solution and crystalizing the magnesium values as magnesium sulfate (MgSO4). The composition of a first Ni-Co MHP was analyzed and is illustrated in Table 2. Various process parameters in accordance with an embodiment of the present disclosure are illustrated in Table 3.

[0052] Table 2: Composition (wt. %) of the first Ni-Co MHP.

[0053] Table 3: Exemplary process parameters.

[0054] Laterite Leaching

[0055] The laterite samples may be dried at 110°C over a period of 6 h and ground. In an embodiment of the present disclosure, the sample is ground to a particle size of P80 (105 pm). Grinding of the feed material provides for increasing the surface area of the feed material available for the subsequent extraction (leaching) step, in turn providing for enhanced leaching rates. The dried samples may subsequently be subjected to either atmospheric leaching using sulfuric acid, or atmospheric leaching at ambient and moderate temperatures using sulfuric acid in the presence of a small amount of a reductant (RR). In an embodiment of the present disclosure, the laterite leaching step is advantageously performed using an ultrasound assisted extraction step, more specifically an acid leaching/sonication step. In an embodiment of the present disclosure, the laterite leaching step is advantageously performed using an ultrasound assisted extraction step, more specifically an acid leaching/sonication step, in the presence of a small amount of a reductant (RR). The conditions of various leaching experiments in accordance with embodiments of the present disclosure are illustrated in Table 4. The extraction efficiencies of various metal values (Ni, Co, Cr, Fe, Al, Mn, Mg, V and Sc) for selected leaching tests are illustrated in Table 5. Of note, during the leaching tests, any water lost was compensated by the addition of fresh water in order to maintain a substantially constant S/L ratio in the reactor.

[0056] Table 4: Exemplary atmospheric leaching tests and conditions.

COMP: Composite sample; LT: Leach Test [0057] Table 5: Extraction efficiencies of various metal values (Ni, Co, Cr, Fe, Al, Mn, Mg, V and Sc) for selected leaching tests.

[0058] With reference to Tables 4 and 5, and FIG. 2, almost no difference in Co, Ni and Sc recoveries could be observed for reductant (RR) values ranging between 0.3 kg/t and 1 kg/t. However, a slight increase could be observed for RR> 1 kg/t. As regarding leaching times, a slight decrease could be observed for the recovery of Ni for extraction times ranging between 60 min - 100 min. However, the recovery could be observed to increase again for extraction times of 120 min or higher. As regarding H2SO4 concentration, it could be observed that at lower concentrations the recovery of the Ni values was < 60%. However, with increasing concentrations the recovery of the Ni values increased to >95% while that of Co was at or near 100%. In an embodiment of the present disclosure, the atmospheric leaching was conducted as follows: H2SO4 ratio (t/t) = 1 (acid /ore); H2SO4 cone. = 3.5 M; RR ratio = 0.3 kg/t (weight RR/weight ore); S/L ratio = 0.35; Temperature = 95°C; and Leaching time = 120 minutes. [0059] MHP Recovery - First Iron Removal Step

[0060] With reference to FIG. 1 , the first iron removal step was advantageously performed using calcium carbonate (CaCCh). In an embodiment of the present disclosure, a CaCCh slurry (25 wt.%) was prepared using deionized water. The slurry was subsequently added dropwise to the pregnant leach solution (PLS) under agitation until a desired pH was reached. The pH was carefully monitored to prevent supersaturation of the elements to be removed by precipitation (e.g., Fe, Al, and Cr). The performance of the first iron removal step was determined at a pH ranging from about 2.0 to about 3.5, and more specifically at pH 2.0, 2.5, 3.0 and 3.5 respectively, while keeping the temperature of the PLS at 90°C and the duration of the first iron removal step at 2 hours (Table 6 and FIG. 3). In subsequent experiments, the temperature of the pregnant leach solution (PLS) and the duration of the first iron removal step were varied while keeping the pH at a predetermined value. To that effect, the performance of the first iron removal step was determined at PLS temperatures ranging from 50°C to 90°C, and more specifically at 50°C, 70°C and 90°C respectively (Table 7 and FIG. 4). Moreover, the performance of the first iron removal step was determined for durations ranging from 1 hour to 3 hours, and more specifically for 1 hour, 2 hours and 3 hours respectively (Table 8 and FIG. 5). The resulting precipitates were isolated by filtration, washed with deionized water, and dried. In an embodiment of the present disclosure, the first iron removal step was conducted at pH = 2.5, a temperature of 90°C, and a precipitation time of 2 hours.

[0061] Table 6: Precipitation recovery as a function of pH, at 90°C, and precipitation duration of 2 hours.

[0062] More than 90% of Fe, about 20 % of Al, and about 57% of Cr were removed at pH 2.50, while the nickel and cobalt values remained in solution. [0063] Table 7: Precipitation recovery as a function of temperature, at pH = 2.5, and precipitation duration of 2 hours.

[0064] Al, Cr and Fe precipitation was optimal at 90°C, with Fe and Cr values of 91 % and 83% respectively, while the nickel and cobalt values remained in solution.

[0065] Table 8: Precipitation recovery as a function of time, at pH = 2.5, and at a temperature of 90°C.

[0066] At a precipitation time of 3 hours, some Ni losses (up to 6%) were noted. At a precipitation time of 2 hours, > 90% of Fe could be recovered while the nickel and cobalt values remained in solution.

[0067] MHP Recovery - Second Iron Removal Step

[0068] For the second iron removal step, the second pregnant solution obtained following the first iron removal step (/.e. partially purified pregnant leach solution) may optionally be subjected to an oxidation step, oxidizing any residual ferrous iron (Fe ²⁺ ) in the second pregnant solution to ferric iron (Fe ³⁺ ). In an embodiment of the present disclosure, the oxidation is advantageously performed using an aqueous solution of hydrogen peroxide (H2O2). In a further embodiment of the present disclosure, the aqueous H2O2 solution has a mass percentage (w/w) of about 50% w/w. In yet a further embodiment of the present disclosure, the amount of H2O2 solution added to the second pregnant solution provides for about twice the stoichiometric amount of ferrous iron (Fe ²⁺ ) present in the second pregnant solution. In yet a further embodiment of the present disclosure, the ferrous iron (Fe ²⁺ ) to ferric iron (Fe ³⁺ ) oxidation was carried out at a pH of 3.5 and for a duration of 2 hours. In yet a further embodiment of the present disclosure, the second pregnant solution is obtained using conditions determined to be optimal (/.e., temperature, pH and duration) for the first iron removal step. In yet a further embodiment of the present disclosure, the second iron removal step may be conducted without the oxidation step.

[0069] The second pregnant solution obtained following the first iron removal step, either following an oxidation step or without a prior oxidation step, is further treated with a CaCCh slurry (12.5 wt.%), raising the pH of the second pregnant solution to between about 3.5 and about 4.5. In addition to removing residual iron from the pregnant leach solution, the second iron removal step advantageously further reduces any residual aluminum and chromium content. The performance of the second iron removal step was determined at pH 3.5, 4.0 and 4.5 respectively, while keeping the temperature of the second pregnant solution at 70°C and the duration of the second iron removal step at 1 hour (Table 9 and FIG. 6). In subsequent experiments, the temperature of the second pregnant leach solution and the duration of the second iron removal step were varied while keeping the pH at a predetermined value. To that effect, the performance of the second iron removal step was determined at temperatures ranging from 25°C to 70°C, and more specifically at 25°C, 50°C and 70°C respectively, while maintaining the pH at 3.5 and the precipitation duration at 1 hour (Table 10 and FIG. 7). Moreover, the performance of the second iron removal step was determined for durations ranging from 0.5 hour to 1.5 hours, and more specifically at 0.5 hour, 1 hour and 1.5 hours respectively, while maintaining the pH at 3.5 and the temperature of the second pregnant solution at 70°C (Table 11 and FIG. 8). In an embodiment of the present disclosure, the second iron removal step was conducted at pH = 3.5, a temperature of 70°C, and a precipitation time of 1 hour.

[0070] Table 9: Precipitation recovery as a function of pH, at 70°C, and precipitation duration of 1 hour.

[0071] Nickel losses were observed to increase with increasing pH, with minimal losses (/.e., < 0.1 %) at pH = 3.5. Moreover, at pH = 3.5, up to 38% of the residual Al and ~ 17% of the residual Cr could be removed. The low iron removal (0.8%) efficiency could be explained by the presence of significant amounts of ferrous iron (Fe ²⁺ ), which require higher pH values for precipitation. This situation may be advantageously remedied by subjecting the second pregnant solution to an oxidation step, oxidizing any residual ferrous iron (Fe ²⁺ ) in the second pregnant solution to ferric iron (Fe ³⁺ ), prior to treatment with the CaCCh slurry.

[0072] Table 10: Precipitation recovery as a function of temperature, at pH = 3.5, and precipitation duration of 1 hour.

[0073] At a temperature of 25°C, no precipitation of any of the metal values (e.g., Mn, Ni, Co, Fe, Al and/or Cr) could be observed. However, a significant increase in the precipitation of the Al and Cr values could be observed at 70°C, with minimal Ni losses (< 0.1 %).

[0074] Table 11 : Precipitation recovery as a function of time, at pH = 3.5, and at a temperature of 70°C.

[0075] At a precipitation time of 1 hour, 37.5 % and 16.9% of the residual Al and Cr values could be removed, while the nickel and substantially all of the cobalt values remained in solution.

[0076] The composition of a solution following the first and second iron removal steps, in accordance with an embodiment of the present disclosure, is illustrated in Table 12. The iron content in the solution could be lowered to ~ 70 ppm.

[0077] Table 12: Chemical composition of a solution following first and second iron removal steps.

[0078] MHP Recovery - First MHP Recovery (MHP1)

[0079] For the first nickel and cobalt recovery step, the “first mixed hydroxide precipitation (MHP1)”, a MgO slurry (1-25 wt.%) was prepared using deionized water. In an embodiment of the present disclosure, a 10 wt.% MgO slurry was prepared. The slurry was subsequently added dropwise to the solution obtained following the first and second iron removal steps under agitation until a desired pH was reached. In an embodiment of the present disclosure, the pH of the solution was raised to between about 7.0 and about 7.5. The performance of the first MPH recovery was determined at different pH values, temperatures, and durations. The optimal precipitation conditions provide for the precipitation of both Ni and Co while minimizing the precipitation of Mn as well as other metal impurities. The optimal pH was determined by performing the first MHP at a pH ranging between about 7.0 and about 7.5, and more specifically at pH 7.0, 7.2 and 7.4 respectively, while keeping the precipitation temperature at 50°C and the precipitation duration at 1 hour (Table 13 and FIG. 9). In subsequent experiments, the temperature of the solution and the duration of the first nickel and cobalt recovery step were varied while keeping the pH at a predetermined value. To that effect, the performance of the first nickel and cobalt recovery step was determined at temperatures ranging from 25°C to 70°C, and more specifically at 25°C, 50°C and 70°C respectively, while maintaining the pH at 7.0 and the precipitation duration at 1 hour (Table 14 and FIG. 10). Moreover, the performance of the first nickel and cobalt recovery step was determined for durations ranging from 0.5 hour to 1.5 hours, and more specifically for 0.5 hour, 1 hour, and 1.5 hours respectively, while maintaining the pH at 7.0 and the temperature at 50°C (Table 15 and FIG. 11). In an embodiment of the present disclosure, the first nickel and cobalt recovery step was conducted at pH = 7.0, a temperature of 50°C, and a precipitation time of 1 hour. In yet a further embodiment of the present disclosure, the pregnant solution that is subjected to the first mixed hydroxide precipitation is obtained following the first and second iron removal steps, under conditions determined to be optimal (/.e., temperature, pH and duration). [0080] Table 13: Precipitation recovery as a function of pH, at 50°C, and precipitation duration of 1 hour.

[0081] Ni and Co recovery increased with increasing pH. However, increasing the pH also resulted in an increase of the recovery of the Mn values. Keeping the pH between about 7.0 and 7.2 provided for good Ni and Co recovery while also minimizing precipitation of the Mn values.

[0082] Table 14: Precipitation recovery as a function of temperature, at pH = 7.0, and precipitation duration of 1 hour.

[0083] Ni and Co recovery increased with increasing temperature. However, increasing the temperature also resulted in an increase of the recovery of the Mn values. To that effect, the recovery of the Mn values increased significantly at temperatures ranging between 50-70°C. Keeping the temperature at about 50°C provided for good Ni and Co recovery (about 70% and 38% respectively), while also minimizing precipitation of the Mn values.

[0084] Table 15: Precipitation recovery as a function of time, at pH = 7.0, and at a temperature of 50°C.

[0085] At a precipitation time of 1 hour, about 70% and 38% of the Ni and Co values could be recovered, while also minimizing precipitation of the Mn values.

[0086] The composition of a solution following the first nickel and cobalt recovery step, in accordance with an embodiment of the present disclosure, is illustrated in Table 16. [0087] Table 16: Chemical composition of a solution following the first first nickel and cobalt recovery step.

[0088] MHP Recovery - Second MHP Recovery (MHP2)

[0089] For the second nickel and cobalt recovery step, the “second mixed hydroxide precipitation (MHP2)”, the solution obtained following the first nickel and cobalt recovery step may advantageously be subjected to a second MHP. The solution obtained following the first nickel and cobalt recovery step, is further treated with a MgO slurry (1-25 wt.%), raising the pH to between about 7.8 and about 8.2. In an embodiment of the present disclosure, a 20 wt.% MgO slurry was prepared. The performance of the second nickel and cobalt recovery step was determined at pH 7.8, 8.0 and 8.2 respectively, while keeping the temperature of the second pregnant solution at 60°C and the duration of the second nickel and cobalt recovery step at 1 hour (Table 17 and FIG. 12). In subsequent experiments, the temperature of the solution and the duration of the second nickel and cobalt recovery step were varied while keeping the pH at a predetermined value (/.e., between 7.8 - 8.0). To that effect, the performance of the second nickel and cobalt recovery step was determined at temperatures ranging from 25°C to 70°C, and more specifically at 25°C, 50°C and 60°C respectively, while maintaining the pH at 8.0 and the precipitation duration at 1 hour (Table 18 and FIG. 13). Moreover, the performance of the second nickel and cobalt recovery step was determined for durations ranging from 1.0 hour to 2.0 hours, and more specifically for 0.5 hour, 1 .0 hour, and 1 .5 hours respectively, while maintaining the pH and the temperature of the second pregnant solution at 8.0 and 60°C respectively (Table 19 and FIG. 14). In an embodiment of the present disclosure, the second nickel and cobalt recovery step was conducted at pH = 8.0, a temperature of 60°C, and a precipitation time of 1 hour. In an embodiment of the present disclosure, the second Ni-Co MHP may advantageously be recycled into the leaching step to improve nickel recovery in the first MHP recovery, and to also minimize losses in Ni and Co recovery.

[0090] Table 17: Precipitation recovery as a function of pH, at 60°C, and precipitation duration of 1 hour.

[0091] Ni and Co recovery increased with increasing pH. However, increasing the pH also resulted in an increase of the recovery of the Mn values. Keeping the pH between about 7.8 and 8.0 provided for good Ni and Co recovery while also minimizing precipitation of the Mn values.

[0092] Table 18: Precipitation recovery as a function of temperature, at pH = 8.0, and precipitation duration of 1 hour.

[0093] Ni and Co recovery increased with increasing temperature. However, increasing the temperature also resulted in an increase of the recovery of the Mn values. To that effect, the recovery of the Mn values increased significantly at temperatures ranging between 50-60°C. In view of one of the objectives being the maximization of the Ni recovery, and in view of the second Ni-Co MHP being advantageously recycled into the leaching step to improve nickel recovery in the first MHP recovery, the temperature was kept at about 60°C.

[0094] Table 19: Precipitation recovery as a function of time, at pH = 8.0, and at a temperature of 60°C. [0095] At a precipitation time of 1 hour, about 50% and 10% of the Ni and Co values respectively could be recovered, while also minimizing precipitation of the Mn values.

[0096] The composition of a solution following the second nickel and cobalt recovery step, in accordance with an embodiment of the present disclosure, is illustrated in Table 20. About 81 % and 100% respectively of the residual Ni and Co values could be precipitated.

[0097] Table 20: Chemical composition of a solution following the second nickel and cobalt recovery step.

[0098] Manganese Removal

[0099] Following the first and second MHP recover steps, a solution enriched in manganese and magnesium values is obtained. The solution enriched in manganese and magnesium values is further treated with a MgO slurry (15-25 wt.%), raising the pH of the solution to between about 8.5 and about 9.0. In an embodiment of the present disclosure, a 20 wt.% MgO slurry was prepared. The performance of the manganese removal was determined at different pH values, temperatures, and durations. The optimal pH was determined by performing the manganese removal at a pH ranging between about 8.5 and about 9.0, and more specifically at pH 8.5, 8.8 and 9.0 respectively, while keeping the precipitation temperature at 50°C and the precipitation duration at 1 hour (Table 21 and FIG. 15). In subsequent experiments, the temperature of the solution and the duration of the manganese removal step were varied while keeping the pH at a predetermined value. To that effect, the performance of the manganese removal step was determined at temperatures ranging from 25°C to 70°C, and more specifically at 25°C, 50°C and 60°C respectively, while maintaining the pH at 9.0 and the precipitation duration at 1 hour (Table 22). Moreover, the performance of the manganese removal step was determined for durations ranging from 0.5 hour to 1 .5 hours, and more specifically for 0.5 hour, 1 hour, and 1.5 hours respectively, while maintaining the pH and the temperature of the solution enriched in manganese and magnesium values at 9.0 and 50°C respectively (Table 23 and FIG. 16). In an embodiment of the present disclosure, the manganese removal step was conducted at pH = 9.0, a temperature of 50°C, and a precipitation time of 1 hour. In yet a further embodiment of the present disclosure, the solution enriched in manganese and magnesium values is obtained following the first and second iron removal steps, and first and second MHP recovery steps, under conditions determined to be optimal (/.e., temperature, pH and duration).

[00100] Table 21 : Precipitation recovery as a function of pH, at 50°C, and precipitation duration of 1 hour.

[00101] The highest Mn recovery was observed at pH = 9 where ~25% of the Mn values could be recovered.

[00102] Table 22: Precipitation recovery as a function of temperature, at pH = 9.0, and precipitation duration of 1 hour.

[00103] Mn recovery increased with increasing temperatures. However, increasing the temperature also resulted in an increase of the recovery of the Mg values. Keeping the temperature at about 50°C provided for good Mn recovery, while also considering the precipitation of the Mg values.

[00104] Table 23: Precipitation recovery as a function of time, at pH = 9.0, and at a temperature of 50°C. [00105] Mn recovery increased with increasing precipitation duration. However, increasing the duration also resulted in an increase of the recovery of the Mg values. Keeping the duration at about 1 h provided for good Mn recovery, while also considering the precipitation of the Mg values.

[00106] The composition of a solution following the Mn recovery step, in accordance with an embodiment of the present disclosure, is illustrated in Table 24.

[00107] Table 24: Chemical composition of a solution following the Mn recovery step.

[00108] Magnesium Sulfate Crystallization

[00109] The manganese depleted solution, following the manganese removal step is subjected to a magnesium crystallization step to remove the magnesium values as a magnesium sulfate. In an embodiment of the present disclosure, the depleted solution is heated to boiling until a volume reduction of about 80% is reached. The solution was subsequently cooled to about 5°C and kept for a period of 24 hours, promoting the formation of magnesium sulfate (e.g., MgSO4.7H2O) crystals. The magnesium sulfate crystals were removed by filtration, washed, and dried.

[00110] Alternative process for Fe precipitation

[00111] In order to precipitate the Fe values without the concomitant formation of gypsum (CaSO4) as a result of the use of calcium carbonate (CaCOa), the iron removal step may be performed using ammonium hydroxide (NH4OH), providing for the precipitation of the iron values as Fe(OH)a. In an embodiment of the present disclosure, a NH4OH solution (5.8-6.0 wt.%) was prepared using deionized water. The solution was subsequently added dropwise to the pregnant leach solution (PLS) under agitation until a desired pH was reached. The pH was carefully monitored to prevent supersaturation of the elements to be removed by precipitation (e.g., Fe, Al, and Cr). The performance of the iron removal was determined at a pH ranging from about 2.0 to about 4.5, and more specifically at pH 2.5, 3.0, 3.5, 4.0 and 4.5 respectively, while maintaining the temperature of the pregnant leach solution at about 20°C, and the duration of the iron recovery step at 3 hours (Table 25). In subsequent experiments, the temperature of the pregnant leach solution (PLS) and the duration of the iron recovery step were varied while keeping the pH at a predetermined value. To that effect, the performance of the iron recovery step was determined at temperatures ranging from room temperature to 50°C, and more specifically at 22°C and 50°C respectively, while maintaining the pH at 3.0 and the precipitation duration at 2 hours (Table 26). Moreover, the performance of the iron removal step was determined for durations ranging from 1 hour to 3 hours, and more specifically for 1 hour, 2 hours and 3 hours respectively, while maintaining the pH at 3.0 and the temperature at 22°C (Table 27). The resulting precipitates were isolated by filtration, washed with deionized water, and dried. In an embodiment of the present disclosure, the Fe precipitation using ammonium hydroxide (NH4OH) was conducted as follows: pH = 3; temperature = 22°C; and duration = 2 hours.

[00112] Table 25: Precipitation recovery as a function of pH, at 20°C, and precipitation duration of 3 hours.

[00113] At a pH of 3.0, ~90% of the Fe values could be recovered with substantially no Ni losses (<0.25%). The Fe recovery is slightly higher at a pH of 3.5 (~92%), however the Ni losses were also higher (~2.0%).

[00114] Table 26: Precipitation recovery as a function of temperature, at pH = 3.0, and precipitation duration of 2 hours.

[00115] At 22°C and 50°C respectively, the Fe recovery was ~81 %. It thus appears that the temperature has little impact on the Fe recovery when using ammonium hydroxide (NH4OH). However, significant increases in Ni and Co losses were observed at 50°C (5.32% and 2.67% respectively) relative to conducting the Fe recovery at 22°C.

[00116] Table 27: Precipitation recovery as a function of time, at pH = 3.0, and at a temperature of 22°C.

[00117] The precipitation duration has little effect on the Fe recovery. The Fe recovery ranged between 80-81 % for precipitation times of 1-3 hours. However, the Ni losses were higher at 3h relative to 2h.

[00118] With reference to the laterite leaching step, and with reference to FIG. 1 , the laterite feed material may be subjected to an ultrasound assisted extraction step, more specifically an acid leaching/sonication step. This step comprises mixing of the feed material with an aqueous acid solution to provide a slurry and subsequently sonicating the slurry while stirring. The sonication advantageously provides for increased leaching rates, shorter extraction times, and reduced acid consumption. Sonication generates cavitation bubbles which aid in breaking up and/or causing the formation of cracks in the feed material which increases the surface area of the feed material resulting in enhanced leaching rates. To that effect, within heterogeneous systems, such as the leaching of nickel, cobalt, manganese and magnesium values from a laterite feed material, the formation of high velocity microjets resulting from transient cavitation collapse, propagate toward the surface of the laterite feed material leading to pitting and erosion thereby increasing the reactive surface area. Furthermore, transient cavitation results in extreme localized conditions (up to 5000 K and 1000 atm.) resulting in violent collisions and high shear forces. Further advantages to the use of ultrasound in the leaching process of nickel, cobalt, manganese and magnesium values include decreased agglomeration, increased access to a reactive surface by breaking down the particulate feed material (increasing the reactive surface area), improving the diffusion rate, and preventing passivation. In an embodiment of the present disclosure, the acid leaching/sonication step is performed as a batch process. In an embodiment of the present disclosure, the acid leaching/sonication step is performed as a continuous process. Following the ultrasound assisted extraction step, a pregnant leach solution comprising the metal values, in the form of their respective salts, is obtained. In an embodiment of the present disclosure, ultrasound assisted extraction is advantageously used in the processing of a laterite feed material to extract the metal values therefrom. More specifically, ultrasound assisted extraction is advantageously used for the extraction and recovery of nickel, cobalt, manganese, and magnesium values from a laterite feedstock. In a further embodiment of the present disclosure, the acid leaching/sonication step may be performed at temperatures ranging between about 20°C and about 100°C. In a further embodiment of the present disclosure, the acid leaching/sonication step may be performed at temperatures ranging between about 20°C and about 90°C. The use of an ultrasound assisted extraction step advantageously provides for reduced leaching times as well as reduced acid consumption (reduced t/t).

[00119] In an embodiment of the present disclosure, the acid leaching/sonication step is performed using sulfuric acid, converting the metal values of the laterite feed material into their corresponding sulfates. In embodiments of the present disclosure, the leaching solution comprises from about 5 wt.% to about 100 wt.% H2SO4; in a further embodiment from about 5 wt.% to about 90 wt.% H2SO4; in a further embodiment from about 10 wt.% to about 80 wt.% H2SO4; in a further embodiment from about 15 wt.% to about 70 wt.% H2SO4; in a further embodiment from about 20 wt.% to about 60 wt.% H2SO4; in a further embodiment from about 30 wt.% to about 50 wt.% H2SO4; about 5 wt.% H2SO4; about 10 wt.% H2SO4; about 15 wt.% H2SO4; about 20 wt.% H2SO4; about 25 wt.% H2SO4; about 30 wt.% H2SO4; about 35 wt.% H2SO4; about 40 wt.% H2SO4; about 45 wt.% H2SO4; about

50 wt.% H2SO4; about 55 wt.% H2SO4; about 60 wt.% H2SO4; about 65 wt.% H2SO4; about

70 wt.% H2SO4; about 75 wt.% H2SO4; about 80 wt.% H2SO4; about 85 wt.% H2SO4; about

90 wt.% H2SO4; about 95 wt.% H2SO4; or about 100 wt.% H2SO4.

[00120] In an embodiment of the present disclosure, the acid leaching/sonication step may be performed using nitric acid (HNO3), converting the compounds of the laterite feed material into their corresponding nitrates. In embodiments of the present disclosure, the leaching solution comprises from about 5 wt.% to about 100 wt.% HNO3; in a further embodiment from about 5 wt.% to about 90 wt.% HNO3; in a further embodiment from about 10 wt.% to about 80 wt.% HNO3; in a further embodiment from about 15 wt.% to about 70 wt.% HNO3; in a further embodiment from about 20 wt.% to about 60 wt.% HNO3; in a further embodiment from about 30 wt.% to about 50 wt.% HNO3; about 5 wt.% HNO3; about 10 wt.% HNO3; about 15 wt.% HNO3; about 20 wt.% HNO3; about 25 wt.% HNO3; about 30 wt.% HNO3; about 35 wt.% HNO3; about 40 wt.% HNO3; about 45 wt.% HNO3; about 50 wt.% HNO3; about 55 wt.% HNO3; about 60 wt.% HNO3; about 65 wt.% HNO3; about 70 wt.% HNO3; about 75 wt.% HNO3; about 80 wt.% HNO3; about 85 wt.% HNO3; about 90 wt.% HNO3; about 95 wt.% HNO3; or about 100 wt.% HNO3.

[00121] In an embodiment of the present disclosure, the acid leaching/sonication step may be performed using hydrochloric acid (HCI), converting the compounds of the laterite feed material into their corresponding chlorides. In embodiments of the present disclosure, the leaching solution comprises from about 5 wt.% to about 100 wt.% HCI; in a further embodiment from about 5 wt.% to about 90 wt.% HCI; in a further embodiment from about 10 wt.% to about 80 wt.% HCI; in a further embodiment from about 15 wt.% to about 70 wt.% HCI; in a further embodiment from about 20 wt.% to about 60 wt.% HCI; in a further embodiment from about 30 wt.% to about 50 wt.% HCI; about 5 wt.% HCI; about 10 wt.% HCI; about 15 wt.% HCI; about 20 wt.% HCI; about 25 wt.% HCI; about 30 wt.% HCI; about 35 wt.% HCI; about 40 wt.% HCI; about 45 wt.% HCI; about 50 wt.% HCI; about 55 wt.% HCI; about 60 wt.% HCI; about 65 wt.% HCI; about 70 wt.% HCI; about 75 wt.% HCI; about 80 wt.% HCI; about 85 wt.% HCI; about 90 wt.% HCI; about 95 wt.% HCI; or about 100 wt.% HCI.

[00122] Ultrasound Assisted Extraction (UAEx) - Laterite Leaching

[00123] In an embodiment of the present disclosure, the UAEx is performed using an external ultrasonic device (UIP2000hdT (2000 W, 25 kHz) provided by Hielscher Ultrasonics) as follows: S/L ratio = 10%; Temperature = 95°C; H2SO4 ratio (t/t) = 1 (acid /ore); Leaching time = 60 minutes; and Flow rate = 57 mL/min. In this particular embodiment, the sonication is performed by conducting a laterite laden sulfuric acid solution through an external sonicator. In a further embodiment, the laterite laden sulfuric acid solution may further comprise a small amount of a reductant (RR). When using an external sonicator, a laterite feed (aqueous slurry) may first be sonicated and then subjected to leaching (FIG. 17). Alternatively a laterite feed (aqueous H2SO4 slurry) may be leached and then subjected to sonication. In yet a further alternative, a laterite feed (aqueous H2SO4 slurry) may be leached, subjected to sonication, and then to further leaching. The resulting pregnant solution (PLS) was analyzed by X-ray fluorescence (XRF). In a further embodiment, the laterite laden sulfuric acid solution may further comprise a small amount of a reductant (RR). The reduced exposure time to sonication is referred to as flash sonication.

[00124] With reference to FIG. 17, a first reactor R1 was used to mix the laterite feed with water to produce a slurry to be pumped through the ultrasound unit (US) at a constant flowrate. The slurry passes through the ultrasound unit at a fixed residence time that is directly correlated with the flowrate. The sonicated slurry is then led to a second reactor R2 in which a predetermined amount of acid (e.g., aqueous H2SO4) is added to generate an acidified slurry. The resulting slurry was then leached at 95°C for a period of 60 minutes providing a pregnant solution. Various process parameters in accordance with an embodiment of the present disclosure are illustrated in Table 28. The extraction efficiency, as determined by the various metal values (Ni, Co, Cr, Fe, Al, Mn, Mg, V and Sc) in the pregnant solution (PLS) is illustrated in Table 29.

[00125] Table 28: Exemplary process parameters.

[00126] Table 28: Extraction efficiencies for selected metal values.

[00127] In an embodiment of the present disclosure, the ultrasound-assisted extraction may be advantageously performed at the natural frequency of the laterite feed material. In further embodiments of the present disclosure, the sonication is performed at a frequency ranging from about 20 to about 200 kHz, from about 30 to about 200 kHz; from about 40 to about 200 kHz; from about 50 to about 200 kHz, from about 60 to about 200 kHz; from about 70 to about 200 kHz; from about 80 to about 200 kHz, from about 90 to about 200 kHz; from about 100 to about 200 kHz; from about 110 to about 200 kHz, from about 120 to about 200 kHz; from about 130 to about 200 kHz; from about 140 to about 200 kHz; from about 150 to about 200 kHz, from about 160 to about 200 kHz; from about 170 to about 200 kHz; from about 180 to about 200 kHz; about 20 kHz; about 30 kHz; about 40 kHz; about 50 kHz; about 60 kHz; about 70 kHz; about 80 kHz; about 90 kHz; about 100 kHz; about 110 kHz; about 120 kHz; about 130, about 140 kHz; about 150 kHz; about 160 kHz; about 170 kHz; about 180, about 190 kHz; or about 200 kHz.

[00128] The efficacy of ultrasound assisted extraction was further determined using laterite feed materials from Cuba and Guatemala. Limonite and saprolite feed materials were subjected to ultrasound assisted extraction of the metal values in sulfuric acid for a period of 60 minutes. The extraction efficiency, as determined for the various metal values (Ni, Co, Sc, Mg, and Fe) in the pregnant solution (PLS), is illustrated in Table 29.

[00129] Table 29: Extraction efficiencies for selected metal values.

[00130] The challenges of separating Fe and Mg from the Ni values, once the Fe and Mg content exceeds a certain threshold, are well documented. Notwithstanding the presence of significant amounts of Fe in the feed materials, as well as Mg in the Guatemala saprolite feed material, the Ni, Co and Sc values could be extracted at values ranging between 93-100% respectively.

[00131] In an embodiment of the present disclosure, the ultrasound-assisted extraction may be advantageously performed at an amplitude ranging from about 1 % to about 100%; from about 5% to about 100%; from about 10% to about 100%; from about 15% to about 100%; from about 20% to about 100%; from about 25% to about 100%; from about 25% to about 100%; from about 30% to about 100%; from about 35% to about 100%; from about 40% to about 100%; from about 45% to about 100%; from about 50% to about 100%; from about 55% to about 100%; from about 60% to about 100%; from about 65% to about 100%; from 70% to about 100%; from about 75% to about 100%; from about 80% to about 100%; from about 85% to about 100%; from about 90% to about 100%; about 5%; about 10%; about 15%; about 20%; about 25%; about 30%; about 35%; about 40%; about 45%;about 50%; about 55%; about 60%; about 65%; about 70%; about 75%; about 80%; about 85%; about 90%;about 95%; or about 100%. [00132] In an embodiment of the present disclosure, the ultrasound-assisted extraction may be advantageously performed at an ultrasound power output ranging from, but not limited to, about 50 W to about 150 W; from about 50 W to about 145 W; from about 55 W to about 140 W; from about 60 W to about 135 W; from about 65 W to about 130 W; from about 70 W to about 125 W; from about 70 W to about 120 W; about 78 W to about 116 W; about 50 W; about 55 W; about 60 W; about 65 W; about 75 W; about 80 W; about 85 W; about 90 W; about 94 W; about 95 W; about 100 W; about 102 W; about 105 W; about 110 W; about 115 W; or about 120 W. In an aspect of the present disclosure, the power output may range between 50 W and 16 000 W. The power output is determined, at least in part, based on the volume to be treated, smaller volumes requiring less power.

[00133] In an embodiment of the present disclosure, the laterite feed material is ground to a particle size ranging from about 3 mm to 60 microns; from about 2 mm to 60 microns; from about 1 mm to 60 microns; from about 0.5 mm to 60 microns; to a particle size less than 3 mm; to a particle size less than 2 mm; to a particle size less than 1 mm; to a particle size less than 0.5 mm; to a particle size less than 0.1 mm; to a particle size less than 0.05 mm; to a particle size less than 0.01 mm; to a particle size of about 100 microns; to a particle size of about 90 microns; to a particle size of about 80 microns; to a particle size of about 70 microns; or to a particle size of about 60 microns. In a further embodiment of the present disclosure, the laterite feedstock is ground to a particle size of less than about 0.500 millimeter. In yet a further embodiment of the present disclosure, the laterite feedstock is ground to a particle size of less than about 0.125 millimeter. In yet a further embodiment of the present disclosure, the laterite feedstock is ground to a particle size of 75 mm (Pso) or less.

[00134] In an embodiment of the present disclosure, the laterite feed materials are obtained from Central America Nickel’s (CAN) Guatemala nickel deposits (Table 1).

[00135] While the present disclosure has been described with reference to specific examples, it is to be understood that the disclosure is not limited to the disclosed examples. To the contrary, the disclosure is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

[00136] All publications, patents and patent applications are herein incorporated by reference in their entirety to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated by reference in its entirety.