Cross-Reference to Related Applications:

The present application claims priority to US provisional patent application number 62/935,999, filed on November 15, 2019, the contents of which are incorporated herein by reference in their entirety.

Technical field

[0001] The present invention relates generally to upgrading coal fines or other carbonaceous materials. More specifically, the present invention relates to polymer-coated coal or other carbonaceous materials.

Background

[0002] Coal is the most abundant solid fossil fuel, and coal production and combustion are significant contributors to the concentration of carbon dioxide in the atmosphere. The majority of electricity comes from burning coal, and coal combustion is the largest source of anthropomorphic carbon dioxide emissions. In 2011 the carbon emissions from burning coal were estimated to be 14,416 million tonnes [Wikipedia, Coal]

[0003] Coal fines are a significant waste problem both in the production and the transportation of coal. Coal fines often contain significant ash, and often cause dust pollution. It has been estimated that up to 10 % of the coal mined today ends up as unusable fines. Many efforts have been made to produce hard, dust free coal pellets from coal fines using numerous binders. While many of these efforts make pellets of coal fines, they generally have not been able to both reduce the carbon footprint of coal and reduce the ash content in the fuel.

[0004] Traditional methods to pelletize fines typically utilize high temperature and pressure, making the process expensive. Many efforts have tried to use binders such as clay, lime, magnesia, starch, and others. However, several issues regarding ash waste and binding of coal fines still remain.

[0005] In addition to the problem of coal fines waste, the ash content of coal also presents a problem in the coal industry. Post -combustion ash requires removal and cleaning of furnaces, and adds to transportation costs of coal without contributing to energy production. Traditional methods for decreasing ash typically involve treatments with harsh inorganic acids at low pH, causing corrosion of vessels and increasing safety concerns. Although low-ash coal is desirable, these methods for upgrading coal are often avoided due to problems associated therewith.

[0006] Alternative, additional, and/or improved coal products, and methods and apparatus for reducing ash content and/or coal fines waste is desirable. Summary of Invention

[0007] The invention has a number of aspects that may be exploited individually or in combination.

[0008] As described herein, a good binder for coal fines would have low ash content, low moisture content, and a high heating value, and as further described herein, the hydrothermal polymerization of saccharide materials may produce a material that meets these criteria. Furthermore, by using catalyzed hydrothermal processes on a mixture of coal fines and polysaccharides such as cellulose and hemicellulose derived from biomass, it has been found that ash in the coal may be reduced when the biomass is converted into a high energy density polymeric solid that coats the coal fines in a manner allowing hard pellets to be produced from the coal and biomass mixture.

[0009] In an embodiment, there is provided herein a method for producing a hard fuel pellet from input materials comprising coal fines and one or more of: polysaccharides (such as cellulose, hemicellulose, amylose or related materials), saccharides, or saccharide precursors, which may be derived generally from biomass. The method may, by way of non-limiting examples, take as a feedstock lignite, bituminous or anthracite coal fines and a combination of one or more of: wood chips or sawdust of pine, hemlock, birch, alder aspen, balsam etc., forest cuttings, branches and leaves, wood demolition waste, pulp, paper, cardboard, plant material (for example, sugar cane bagasse, water hyacinth, palm nut kernels, oil palm trunks, rice husks, milfoil weeds), grasses including but not limited to Giant King Grass, Miscanthus, agricultural wastes (for example straw, plant cuttings, corn stover, corn cobs), animal manure (including but not limited to horse, cow, bison and pig manure), municipal wastes (for example food waste, yard waste, paper based disposable cups and plates, waste paper, cardboard waste, brewers waste), any mixtures of the above and the like. The method may involve providing a slurry of the coal fines feedstock and biologically based feedstock and heating the slurry under acidic conditions. In some embodiments, one or more weak organic acids may be present in the slurry. In an embodiment, one or more of the weak organic acids may comprise an acid having a pKa in the range of 1.2 to 3.85.

[0010] In another embodiment, there is provided herein a method for producing a low-ash coal- polymer composite by simultaneously displacing alkali metals and alkali earth elements bound to the coal while chemically binding a carbon neutral hydrothermal polymer to the coal fines.

[0011] In another embodiment, there is provided herein a method to produce hard pellets from coal fines with a reduced ash content and a reduced carbon footprint by subjecting a mixture of coal fines and saccharides, generally derived from biomass, to a hydrothermal polymerization process at a temperature and pressure above ambient conditions to produce a mixture of coal and hydrothermal polymer; removing ash forming components from the coal and producing a hard pellet by compressing the dried solids in a standard pellet press. [0012] In another embodiment, there is provided herein an apparatus for producing the hydrothermal-polymer-coal composite, the apparatus comprising: a mixing tank where the coal fines, biomass, water and homogeneous catalyst are slurried; a pressure vessel where the slurry is heated to a sufficient temperature and pressure; an output receiver where the slurry is constrained after processing; a filtration unit to recover the catalyst solution from the solids; a washing system; a dewatering system to reduce the moisture content to a level where the solids can be pelletized and a pelletizer where the hydrothermal-polymer-coal composite is pressed into hard pellets.

[0013] In yet another embodiment, there is provided herein a method for producing a hydrothermal-polymer-coal composite from a feedstock comprising a coal or carbonaceous material and a biomass comprising one or more of saccharides, di-saccharides, polysaccharides, carbohydrates, cellulose, hemicellulose, or amylose, the method comprising: providing a substantially aqueous slurry of the coal or carbonaceous material and the biomass; making the slurry acidic; and cooking the slurry at a temperature in a range of about 170°C to about 260°C and a pressure in excess of atmospheric pressure for a time sufficient to cause the biomass to react to yield solid polymeric carbon compounds (hydrothermal polymers).

[0014] In another embodiment of the above method, making the slurry acidic may comprise adding an acid to the slurry.

[0015] In still another embodiment of the above method or methods, the acid may comprise a weak organic acid. In still another embodiment, the weak organic acid may comprise an acid having a pKa in a range of about 1.2 to about 3.85. In yet another embodiment, the weak organic acid may comprise carbonic, formic, maleic, or oxalic acid, or any mixture of one or more thereof.

[0016] In still another embodiment of the above method or methods, the pH of the acidic slurry may be between about 1.0 and about 4.0. In certain further embodiments, the pH of the acidic slurry may be between about 1.0 and 3.0, for example.

[0017] In another embodiment of the above method or methods, the cooking may be performed for a time range of about 5 minutes to about 180 minutes.

[0018] In yet another embodiment of the above method or methods, making the slurry acidic may comprise adding an organic acid anhydride. In certain embodiments, the organic acid anhydride may comprise carboxylic anhydride, formic anhydride, maleic anhydride, oxalic anhydride, or acetic anhydride, or any mixture of one or more thereof. [0019] In still another embodiment of the above method or methods, the acid may comprise a weak inorganic acid. In certain embodiments, the weak inorganic acid may comprise phosphoric acid, phosphorous acid, or any mixture thereof.

[0020] In yet another embodiment, there is provided herein a method for producing a low-ash hydrothermal-polymer-coal composite from a feedstock comprising a coal and a biomass comprising one or more of saccharides di-saccharides, polysaccharides, carbohydrates, cellulose, hemicellulose, or amylose, the method comprising: providing a substantially aqueous slurry of the coal and the biomass; making the slurry acidic; cooking the slurry at a temperature in a range of about 170°C to about 260°C and a pressure in excess of atmospheric pressure that is sufficient to maintain the slurry in a liquid state, and for a time sufficient to cause the biomass to react to yield solid polymeric carbon compounds (hydrothermal polymers); and separating the hydrothermal-polymer-coal composite from the solution and washing the hydrothermal-polymer-coal composite to remove residual soluble materials from the hydrothermal-polymer-coal composite.

[0021] In yet another embodiment, there is provided herein a method to produce a hard hydrothermal-polymer-coal composite pellet, brick, or block from carbonaceous material and biomass, said method comprising: forming a mixture of carbonaceous material, biomass, and a catalyst in an acidic slurry; cooking the slurry at a temperature in a range of about 170°C to about 260°C and a pressure in excess of atmospheric pressure that is sufficient to maintain the slurry in a liquid state, and for a time sufficient to cause the biomass to react to yield solid polymeric carbon compounds (hydrothermal polymers); separating the slurry to obtain a solid hydrothermal-polymer-coal composite and an acidic solution; subjecting the hydrothermal-polymer-coal composite to a washing step, in which the hydrothermal-polymer-coal composite is mixed with a wash water; separating the hydrothermal-polymer-coal composite solids from the wash water; drying the hydrothermal-polymer-coal composite solids sufficiently to allow the solids to be pressed into a hard pellet, brick or block; and pressing the hydrothermal-polymer-coal composite into a hard pellet, brick or block. [0022] In still another embodiment of the above method or methods, cooking the slurry may be performed in a pressure vessel, and the method may comprise filling a headspace area within the pressure vessel with C0 prior to cooking the slurry.

[0023] In still another embodiment of the above method or methods, the pH of the acidic slurry may be between about 1.0 and about 4.0. In another embodiment, the pH of the acidic slurry may be between about 1. 0 and about 3.0, for example.

[0024] In yet another embodiment of the above method or methods, the slurry may be made acidic by adding an acid to the slurry.

[0025] In certain embodiments, the acid may comprise a weak organic acid. In further embodiments, the weak organic acid may comprise a weak acid having a pKa in a range of about 1.2 to about 3.85. In still another embodiment, the weak acid may be an organic acid which may be carbonic, formic, acetic, maleic, malonic, or oxalic acid, or a mixture of one or more thereof.

[0026] In another embodiment, the acid may comprise an inorganic acid. In certain embodiments, the acid may comprise phosphoric acid.

[0027] In still another embodiment, the acid may be a strong acid. In a further embodiment, the strong acid may comprise sulphuric, hydrochloric, hydrobromic, or nitric acid, or any combination thereof.

[0028] In another embodiment of the method or methods above, the cooking may be performed for a time in a range of about 5 minutes to about 180 minutes.

[0029] In yet another embodiment of the method or methods above, the coal or carbonaceous material may be or comprise coal fines.

[0030] In still another embodiment of the method or methods above, the coal fines may comprise fines of lignite, bituminous, or anthracite coal, or any mixture thereof.

[0031] In yet another embodiment of the above method or methods, the fines may have a size of 1mm or less.

[0032] In still another embodiment of the above method or methods, the biomass feedstock may comprise one or more of: polysaccharides, cellulose, hemicellulose, amylose, monosaccharides, a sugar, wood chips, sawdust, bark, chips of pine, fir, hemlock, spruce cedar, birch, alder, aspen or balsam, forest cuttings, branches leaves, wood demolition waste, pulp, paper, plant biomass, water hyacinth, marine plants, algae, cyanobacteria, agricultural wastes, straw, plant cuttings, corn stover, corn cobs, bagasse, palm oil production waste, animal manures including horse manure, cow manure, and bison manure, municipal wastes, food waste, yard waste, paper waste, waste cardboard, brewers' waste and mixtures of one or more thereof. [0033] In yet another embodiment of the above method or methods, the carbonaceous material may comprise torrified biomass comprising material torrified from wood chips, sawdust, bark, chips of pine, fir, hemlock, spruce cedar, birch, alder, aspen or balsam, forest cuttings, branches leaves, wood demolition waste, pulp, paper, plant biomass, water hyacinth, marine plants, algae, cyanobacteria, agricultural wastes, straw, plant cuttings, corn stover, corn cobs, bagasse, palm oil production waste, animal manures including horse manure, cow manure, and bison manure, municipal wastes, food waste, yard waste, paper waste, waste cardboard, brewers' waste or any mixture of one or more thereof.

[0034] In another embodiment, there is provided herein a solid hydrothermal-polymer-coal composite produced according to a method as described herein.

[0035] In another embodiment, the hydrothermal-polymer-coal composite may have a calorific value of about 24 MJ/Kg or greater.

[0036] In still another embodiment, the hydrothermal-polymer-coal composite may be hydrophobic.

[0037] In yet another embodiment, there is provided herein a solid hydrothermal-polymer-coal composite produced according to a method as described herein, where an amount of ash after combustion of the hydrothermal-polymer-coal composite is less than that of an equivalent mixture of coal and hydrothermal polymer.

[0038] In yet another embodiment, there is provided herein a composition comprising coal fines or other carbonaceous material coated with a polymer, the polymer being a product of hydrothermal polymerization of a biomass.

[0039] In yet another embodiment, there is provided herein a composition comprising coal fines or other carbonaceous material coated with a saccharide or carbohydrate-based hydrothermal polymer.

[0040] In another embodiment of the above composition or compositions, the composition may be in the form of one or more pellets, bricks, blocks, or other construct(s) collecting a plurality of the coated coal fines or other carbonaceous material.

[0041] In still another embodiment of the composition or compositions above, the polymer may be covalently bound to the coal fines or other carbonaceous material.

[0042] In another embodiment of the composition or compositions above, the biomass may comprise or consist of one or more of saccharides, di-saccharides, polysaccharides, carbohydrates, cellulose, hemicellulose, or amylose.

[0043] In still another embodiment of the composition or compositions above, the hydrothermal polymerization of the biomass may be under acidic conditions. [0044] In yet another embodiment of the composition or compositions above, the hydrothermal polymerization of the biomass may be in the presence of one or more weak organic or inorganic acids.

[0045] In still another embodiment of the composition or compositions above, the one or more weak organic acids may comprise one or more of carbonic, formic, acetic, maleic, malonic or oxalic acids, or any combination thereof.

[0046] In another embodiment of the composition or compositions above, the one or more inorganic acids may comprise one or more of phosphoric acid, phosphorous acid, or a combination thereof.

[0047] In still another embodiment of the composition or compositions above, the polymer may be derived from hydrothermal polymerization of the biomass in the presence of the coal fines or other carbonaceous material.

[0048] In another embodiment of the composition or compositions above, the composition may have a calorific value of about 24 MJ/Kg, or greater.

[0049] In still another embodiment of the composition or compositions above, the composition may be hydrophobic.

[0050] In yet another embodiment of the composition or compositions above, an amount of ash remaining after combustion of the composition may be less than that remaining after combustion of an equivalent mixture of polymer and non-coated coal fines or other carbonaceous material.

[0051] In still another embodiment of the composition or compositions above, the composition may comprise a ratio of the coal fines or other carbonaceous material to the polymer of about 55 to about 90 coal fines or other carbonaceous material : about 45 to about 10 polymer by mass. In still a further embodiment, the composition may comprise a ratio of the coal fines or other carbonaceous material to the polymer of about 55 to about 75 coal fines or other carbonaceous material : about 45 to about 25 polymer by mass, for example.

[0052] In another embodiment of the composition or compositions above, the pellet, brick, block, or other construct collecting a plurality of the coated coal fines or other carbonaceous material may have enhanced durability as compared with an equivalent construct collecting a plurality of non-coated coal fines or other carbonaceous material and polymer.

[0053] In another embodiment, there is provided herein a use of a composition as described herein to produce energy by combustion.

[0054] In still another embodiment, there is provided herein a method for producing a composition comprising a polymer-coated coal or other carbonaceous material, said method comprising: providing a substantially aqueous slurry of the coal or other carbonaceous material and a biomass, the aqueous slurry being acidic; and subjecting the aqueous slurry to hydrothermal polymerization conditions, for a time sufficient for at least one organic component of the biomass to undergo hydrothermal polymerization to yield the polymer-coated coal or other carbonaceous material.

[0055] In yet another embodiment of the above method, the organic component of the biomass may comprise at least one saccharide, di-saccharide, polysaccharide, carbohydrate, cellulose, hemicellulose, or amylose, or any mixture thereof.

[0056] In still another embodiment of the above method or methods, the hydrothermal polymerization conditions may comprise a temperature in a range of about 170°C to about 260°C, and a pressure in excess of atmospheric pressure.

[0057] In still another embodiment of the above method or methods, the aqueous slurry may be made acidic by adding an acid to the slurry.

[0058] In still another embodiment of the above method or methods, the acid may comprise a weak organic acid. In a further embodiment, the weak organic acid may have a pKa in a range of about 1.2 to about 3.85. In another embodiment, the weak organic acid may comprise carbonic, formic, acetic, maleic, malonic, or oxalic acid, or any mixture of one or more thereof.

[0059] In still another embodiment of the above method or methods, the acid may comprise a weak inorganic acid. In a further embodiment, the weak inorganic acid may comprise phosphoric acid, phosphorous acid, or any mixture thereof.

[0060] In still another embodiment of the above method or methods, the pH of the aqueous slurry may be between about 1.0 and about 4.0. In certain embodiments, the pH may be between about 1.0 and about 3.0, for example.

[0061] In yet another embodiment of the above method or methods, the aqueous slurry may be subjected to the hydrothermal polymerization conditions for about 5 minutes to about 180 minutes.

[0062] In another embodiment of the above method or methods, the hydrothermal polymerization conditions may result in dehydration reactions and yield the polymer-coated coal or other carbonaceous material with the polymer covalently bound to the coal or other carbonaceous material.

[0063] In yet another embodiment of the above method or methods, the coal may comprise coal fines.

[0064] In still another embodiment of the above method or methods, the method may further comprise a step of separating the polymer-coated coal or other carbonaceous material from the slurry, providing a polymer-coated coal or other carbonaceous material fraction and an aqueous fraction.

[0065] In yet another embodiment, the method or methods above may further comprise a step of washing the polymer-coated coal or other carbonaceous material fraction to remove soluble intermediates and/or salts therefrom.

[0066] In still another embodiment, the method or methods above may further comprise a step of drying the polymer-coated coal or other carbonaceous material fraction.

[0067] In another embodiment, the method or methods above may further comprise a step of pelletizing or pressing the polymer-coated coal or other carbonaceous material fraction to produce one or more pellets, bricks, blocks, or other constructs.

[0068] In yet another embodiment, the method or methods above may further comprise a step of recycling the aqueous fraction for making more aqueous slurry.

[0069] In still another embodiment of the above method or methods, the biomass may comprise one or more of polysaccharides, cellulose, hemicellulose, amylose, monosaccharides, a sugar, wood chips, sawdust, bark, chips of pine, fir, hemlock, spruce cedar, birch, alder, aspen or balsam, forest cuttings, branches leaves, wood demolition waste, pulp, paper, plant biomass, water hyacinth, marine plants, algae, cyanobacteria, agricultural wastes, straw, plant cuttings, corn stover, corn cobs, bagasse, palm oil production waste, animal manures including horse manure, cow manure, and bison manure, municipal wastes, food waste, yard waste, paper waste, waste cardboard, brewers' waste, or any mixture thereof.

[0070] In yet another embodiment of the above method or methods, the carbonaceous material may comprise one or more of torrified biomass comprising material torrified from wood chips, sawdust, bark, chips of pine, fir, hemlock, spruce cedar, birch, alder, aspen or balsam, forest cuttings, branches leaves, wood demolition waste, pulp, paper, plant biomass, water hyacinth, marine plants, algae, cyanobacteria, agricultural wastes, straw, plant cuttings, corn stover, corn cobs, bagasse, palm oil production waste, animal manures including horse manure, cow manure, and bison manure, municipal wastes, food waste, yard waste, paper waste, waste cardboard, brewers' waste, or any mixture thereof.

[0071] In yet another embodiment, there is provided herein a composition comprising a polymer-coated coal or other carbonaceous material, produced by a method as described herein.

[0072] In still another embodiment, there is provided herein a use of a composition as described herein to produce energy by combustion.

[0073] In another embodiment, there is provided herein a method for reducing combustion ash waste of a coal sample or other sample of carbonaceous material, said method comprising: coating the coal sample or other sample of carbonaceous material with a polymer by: providing a substantially aqueous slurry of the coal sample or other sample of carbonaceous material and a biomass, the aqueous slurry being acidic; and subjecting the aqueous slurry to hydrothermal polymerization conditions, for a time sufficient for at least one organic component of the biomass to undergo hydrothermal polymerization to yield a polymer-coated coal sample or other sample of carbonaceous material.

[0074] In yet another embodiment, there is provided herein a method for increasing binding of coal fines, said method comprising: coating the coal fines with a polymer by: providing a substantially aqueous slurry of the coal fines and a biomass, the aqueous slurry being acidic; and subjecting the aqueous slurry to hydrothermal polymerization conditions, for a time sufficient for at least one organic component of the biomass to undergo hydrothermal polymerization to yield polymer-coated coal fines.

[0075] In yet another embodiment, there is provided herein an apparatus for producing a composition comprising coal or other carbonaceous material coated with a polymer, the apparatus comprising: a mixing tank configured to receive coal or other carbonaceous material, a biomass, and water, and prepare an acidic substantially aqueous slurry thereof; a pressure vessel in fluid communication with the mixing tank, the pressure vessel configured to receive the acidic aqueous slurry, and to subject the acidic aqueous slurry to hydrothermal polymerization conditions for a time sufficient for at least one organic component of the biomass to undergo hydrothermal polymerization to yield polymer- coated coal or other carbonaceous material; and a separation unit in communication with the pressure vessel, and configured to recover a polymer-coated coal or other carbonaceous material fraction and an acidic aqueous fraction from the acidic aqueous slurry.

[0076] In another embodiment, the apparatus may further comprise a washing unit in communication with the separation unit for receiving and washing the polymer-coated coal or other carbonaceous material fraction.

[0077] In still another embodiment, the apparatus may further comprise a dewatering system configured to receive the polymer-coated coal or other carbonaceous material fraction and to remove water therefrom. [0078] In yet another embodiment, the apparatus may further comprise a pelletizer or press configured to generate pellets, bricks, blocks, or other constructs of the polymer-coated coal or other carbonaceous material.

[0079] In still another embodiment, the mixing tank, pressure vessel, or both, may comprise one or more inputs for adding acid to the aqueous slurry..

Brief description of drawings

[0080] The accompanying drawings illustrate non-limiting examples of embodiments of the invention.

[0081] Figure 1 is a Scanning Electron Microscope image of a hydrothermal-polymer-coal composite particle;

[0082] Figure 2 is a block process diagram according to an example embodiment;

[0083] Figure 3 is a plot showing mass loss as a function of temperature for coal fines, hydrothermally processed coal fines and a hydrothermal-polymer-coal composite produced according to one embodiment;

[0084] Figure 4 is a plot showing the pellet durability as a function of amount of hydrothermal- polymer composite in the pellet for one embodiment compared with pellets made by mixing hydrothermal-polymer, made by processing biomass alone, and coal fines;

[0085] Figure 5 is a plot of stress and strain for a hydrothermal-polymer-coal composite for one embodiment; and

[0086] Figure 6 is a plot showing mass loss as a function of temperature for hydrothermal- polymer-coal composites produced at two different temperatures according to one embodiment along with a hydrothermal polymer made by processing biomass alone, that is, without the inclusion of coal.

Detailed Description

[0087] Throughout the following description, specific details are set forth in order to provide a more thorough understanding of the invention. Flowever, the invention may be practiced without these particulars. In other instances, well known elements may not have been shown or described in detail to avoid unnecessarily obscuring the disclosure. Accordingly, the description and drawings are to be regarded as illustrative, rather than restrictive. Immaterial modifications may be made to the embodiments described here without departing from what is covered by the claims. [0088] As described in detail herein, it how now been found that hydrothermal polymerization (likely resulting from dehydration reactions) of biomass mixed with coal fines in weak organic acids may produce low-ash coal, and polymer-coal composites that are readily pelletized. These developments may be independently and/or collectively realizable. Thus, described herein are low-ash high-energy polymer-coal composites, and methods and apparatus for the production thereof. In certain embodiments, compositions with higher green carbon content are provided, where higher is defined relative to coal fines alone, and green carbon may come from the carbon cycle and not from fossil fuels, which is generally exempt from carbon pricing and taxation, for example.

[0089] In an embodiment, there is provided herein a method for producing a composition comprising a polymer-coated coal or other carbonaceous material, said method comprising: providing a substantially aqueous slurry of the coal or other carbonaceous material and a biomass, the aqueous slurry being acidic; and subjecting the aqueous slurry to hydrothermal polymerization conditions, for a time sufficient for at least one organic component of the biomass to undergo hydrothermal polymerization to yield the polymer-coated coal or other carbonaceous material.

[0090] As will be understood, the coal may comprise any suitable coal material, including but not limited to coal fines. In certain embodiments, the coal may comprise lignite, bituminous, or anthracite coal, or any mixture thereof.

[0091] As will also be understood, the carbonaceous material may comprise any suitable carbon- containing material of interest. By way of non-limiting example, the carbonaceous material may comprise one or more of torrified biomass comprising material torrified from wood chips, sawdust, bark, chips of pine, fir, hemlock, spruce cedar, birch, alder, aspen or balsam, forest cuttings, branches leaves, wood demolition waste, pulp, paper, plant biomass, water hyacinth, marine plants, algae, cyanobacteria, agricultural wastes, straw, plant cuttings, corn stover, corn cobs, bagasse, palm oil production waste, animal manures including horse manure, cow manure, and bison manure, municipal wastes, food waste, yard waste, paper waste, waste cardboard, brewers' waste, or any mixture thereof.

[0092] In certain embodiments, a combination of coal and another carbonaceous material may be used as feedstock.

[0093] In certain embodiments, the biomass may comprise any suitable biomass comprising at least one organic component capable of undergoing hydrothermal polymerization. In certain embodiments, the organic component of the biomass may comprise at least one saccharide, di saccharide, polysaccharide, carbohydrate, cellulose, hemicellulose, or amylose, or any mixture thereof. By way of non-limiting example, in certain embodiments the biomass may comprise one or more of polysaccharides, cellulose, hemicellulose, amylose, monosaccharides, a sugar, wood chips, sawdust, bark, chips of pine, fir, hemlock, spruce cedar, birch, alder, aspen or balsam, forest cuttings, branches leaves, wood demolition waste, pulp, paper, plant biomass, water hyacinth, marine plants, algae, cyanobacteria, agricultural wastes, straw, plant cuttings, corn stover, corn cobs, bagasse, palm oil production waste, animal manures including horse manure, cow manure, and bison manure, municipal wastes, food waste, yard waste, paper waste, waste cardboard, brewers' waste, or any mixture thereof. While the biomass will typically be obtained from natural source(s), it is also contemplated that in certain embodiments the biomass may comprise a biomass which is synthetically produced, or which is purified from a natural biomass. By way of example, in certain embodiments, it is contemplated that the biomass may comprise, or consist of, at least one saccharide, di-saccharide, polysaccharide, carbohydrate, cellulose, hemicellulose, or amylose, or any mixture thereof. Thus, in certain embodiments, the biomass may comprise or consist of a polysaccharide, which may be purified from natural source(s) or synthetically produced (thereby lacking other cellular component(s) typically associated with biomass), for example. In certain embodiments, the biomass may comprise, for example, a commercially available food sugar, or high-fructose corn syrup. In certain embodiments, the biomass may comprise waste paper (containing cellulose), or cardboard (containing cellulose and lignin), for example.

[0094] In certain embodiments, the substantially aqueous slurry may comprise generally any aqueous-based (i.e. water-based) slurry of the coal or other carbonaceous material and the biomass, with the aqueous slurry being acidic. In certain embodiments, the substantially aqueous slurry may typically be almost entirely aqueous in nature, but may include traces of organics from the coal or other carbonaceous material and/or the biomass and/or the acid (where an organic acid is used). The slurry may, in certain embodiments, be made acidic by the addition of an acid to the slurry, or the slurry may be acidic due to acid added to, or already present in, the coal/carbonaceous material, biomass, and/or water of the aqueous slurry. In certain embodiments, the pH of the aqueous slurry may be between about 1.0 and about 4.0. By way of example, in certain embodiments, the pH of the aqueous slurry may be between about 1.0 and about 3.0, for example. In certain examples an acid may be used, and the acid may comprise a weak acid. In certain embodiments, the acid may comprise a weak organic acid. In a further embodiment, the weak organic acid may have a pKa in a range of about 1.2 to about 3.85. In still another embodiment, the weak organic acid may comprise carbonic, formic, acetic, maleic, malonic, or oxalic acid, or any mixture of one or more thereof. In another embodiment, the acid may comprise a weak inorganic acid such as phosphoric acid, phosphorous acid, or any mixture thereof. In certain embodiments, a strong acid may be used, where the strong acid is sufficiently dilute so as to prevent decarboxylation reactions of the coal or other carbonaceous material (which may otherwise cause C0 pressure build-up in the reactor) and/or so as to prevent charring.

[0095] In still further embodiments, the aqueous slurry may be subjected to hydrothermal polymerization conditions, for a time sufficient for at least one organic component of the biomass to undergo hydrothermal polymerization to yield the polymer-coated coal or other carbonaceous material. By way of example, in certain embodiments, the hydrothermal polymerization conditions may comprise a temperature in a range of about 170°C to about 260°C, and a pressure in excess of atmospheric pressure. In certain embodiments, the aqueous slurry may be subjected to the hydrothermal polymerization conditions for about 5 minutes to about 180 minutes.

[0096] In certain embodiments, the coal or other carbonaceous material may be coated by polymer resulting from the hydrothermal polymerization of the organic component(s) of the biomass. The coating may, in certain embodiments, comprise a generally solid coating adhered to the surface of the coal or other carbonaceous material. In certain embodiments, the coating may, when subjected to pressure as a result of (for example) being pressed together during pellet formation, be caused to flow/intersperse around and intertwine/mesh with coating from neighboring fines, and resist subsequent separation so as to provide binding of the coal fines. In certain embodiments, and without wishing to be bound by theory, the hydrothermal polymerization conditions (with acid present) may result in dehydration reactions and yield the polymer-coated coal or other carbonaceous material with the polymer covalently bound to the coal or other carbonaceous material, as is described in further detail hereinbelow. While it is believed that covalent binding occurs to at least some extent, it will be understood that the nature of the binding may be non-covalent (for example, Van der Waals interaction, etc...), or via another interaction between the coal fines and the polymer, such that the coal becomes coated by the polymer. As will be understood, the invention as described herein may be practiced regardless of whether a covalent binding-based mechanistic model occurs.

[0097] In still further embodiments, the polymer-coated coal or other carbonaceous material may be separated from the slurry, providing a polymer-coated coal or other carbonaceous material fraction and an aqueous fraction. As will be understood, the polymer-coated coal or other carbonaceous material may be generally solid, and separable from the aqueous fraction by any suitable technique known to the person of skill in the art having regard to the teachings herein. By way of example, filtration may be used to separate the polymer-coated coal or other carbonaceous material fraction from the aqueous fraction. In certain embodiments, for example, separation may be performed using a belt press or a filter press, or materials may be allowed to settle and the solution decanted off, or a centrifuge may be used to separate the solutions from solution, for example. In certain further embodiments, the aqueous fraction may be recycled for making more aqueous slurry, allowing the method to be repeated with more coal and/or carbonaceous material. This recycling may, in certain embodiments, reduce water and/or acid demand where the method is to be performed on a continuing basis, for example.

[0098] In yet another embodiment, the method or methods above may further comprise a step of washing the polymer-coated coal or other carbonaceous material fraction to remove soluble intermediates and/or salts therefrom. The washing may generally be performed using any suitable washing technique/apparatus known to the person of skill in the art having regard to the teachings herein. By way of example, in certain embodiments, washing may be performed by holding the de-watered coal-biofuel mixture on a screen or filter, and washing water through it. In another example, the coal-biofuel mixture may be placed in a tank of water, and rapidly mixed, and then the contents may be passed through a screen or filter to re-separate the solids from wash water.

[0099] In still another embodiment, the method or methods above may further comprise a step of drying or dewatering the polymer-coated coal or other carbonaceous material fraction. The drying or dewatering may be performed using any suitable drying/dewatering technique/apparatus known to the person of skill in the art having regard to the teachings herein. For example, a filter press or belt press may be used for dewatering. In another example, a centrifugal dewatering may be used, where the solids are contained in a spinning container having perforations to allow escape of water.

[0100] In yet another embodiment, the method or methods above may further comprise a step of pelletizing or pressing the polymer-coated coal or other carbonaceous material fraction to produce one or more pellets, bricks, blocks, or other constructs. The pelletizing or pressing may be performed using any suitable technique/apparatus known to the person of skill in the art having regard to the teachings herein. In certain examples, a simple ring die pellet press may be used, such as those typically used in the production of wood pellets. In another example, a briquetting machine may be used, such as those available from A. C. Neilson, for example.

[0101] Also provided herein are compositions comprising coal fines or other carbonaceous material coated with a polymer, the polymer being a product of hydrothermal polymerization of a biomass. In another embodiment of the above composition, the composition may be in the form of one or more pellets, bricks, blocks, or other construct collecting a plurality of the coated coal fines or other carbonaceous material. As described in detail herein, in certain embodiments, the polymer may be covalently (or non-covalently) bound to the coal fines or other carbonaceous material. In certain embodiments, the hydrothermal polymerization of the biomass may be under acidic conditions, as is described in detail herein.

[0102] In certain embodiments, the composition may comprise a ratio of the coal fines or other carbonaceous material to the polymer of about 55 to about 90 coal fines or other carbonaceous material : about 45 to about 10 polymer by mass. By way of example, in certain embodiments, the composition may comprise a ratio of the coal fines or other carbonaceous material to the polymer of about 55 to about 75 coal fines or other carbonaceous material : about 45 to about 25 polymer by mass.

[0103] In certain embodiments, the composition may have a calorific value of about 24 MJ/Kg, or greater. In certain embodiments, the composition may be hydrophobic. In certain embodiments, an amount of ash remaining after combustion of the composition may be less than that remaining after combustion of an equivalent mixture of polymer and non-coated coal fines or other carbonaceous material. In another embodiment, the pellet, brick, block, or other construct collecting a plurality of the coated coal fines or other carbonaceous material may have enhanced durability as compared with an equivalent construct collecting a plurality of non-coated coal fines or other carbonaceous material and polymer. [0104] In yet another embodiment, there is provided herein an apparatus for producing a composition comprising coal or other carbonaceous material coated with a polymer, the apparatus comprising: a mixing tank configured to receive coal or other carbonaceous material, a biomass, and water, and prepare an acidic substantially aqueous slurry thereof; a pressure vessel in fluid communication with the mixing tank, the pressure vessel configured to receive the acidic aqueous slurry, and to subject the acidic aqueous slurry to hydrothermal polymerization conditions for a time sufficient for at least one organic component of the biomass to undergo hydrothermal polymerization to yield polymer- coated coal or other carbonaceous material; and a separation unit in communication with the pressure vessel, and configured to recover a polymer-coated coal or other carbonaceous material fraction and an acidic aqueous fraction from the acidic aqueous slurry.

[0105] In certain embodiments, the apparatus may further comprise a washing unit in communication with the separation unit for receiving and washing the polymer-coated coal or other carbonaceous material fraction. In still further embodiments, the apparatus may further comprise a dewatering system configured to receive the polymer-coated coal or other carbonaceous material fraction and to remove water therefrom. In yet other embodiments, the apparatus may further comprise a pelletizer or press configured to generate pellets, bricks, blocks, or other constructs of the polymer-coated coal or other carbonaceous material.

[0106] Figure 2 depicts a block process diagram of a method 10 according to an example embodiment of the invention, which is producing an embodiment of a composition as described herein. Coal fines 102 are mixed with mono, di- or poly- saccharides 104 and with acid 106 and optionally, one or more solvents 108 in the mixing stage 30 and then moved to the dehydration / polymerization stage 32. The mixture is heated to a temperature and for a period of time under saturated steam autogenic pressure sufficient to hydrolyse the di- and/or polysaccharides to a monosaccharide then to dehydrate the monosaccharide to hydroxyl methyl furfuraldehyde (HMF) or a derivative thereof and finally polymerize the FIMF and FIMF derivatives to a solid polymer on the surface of the coal fines.

[0107] The slurry 112 contains coal fines coated with hydrothermal polymers, soluble intermediates, soluble ash forming material and solvent. The solids in the slurry are separated from the liquids in the separation stage 34. The soluble components including acid 106' and solvent 108' are optionally recycled back into the reactor for reuse. The wet solids 113 are then washed and dried in the washing and drying stage 36. The dried solids containing coal fines coated with hydrothermal polymers 114 are then pelletized (pelletizing stage 38) into hard pellets 115 giving the final durable dust free pellets consisting of a carbon neutral hydrothermal-polymer-coal composite. [0108] Without wishing to be bound by theory, a proposed mechanistic model is provided for illustrative purposes. However, the invention may be practiced regardless of whether the particulars of the mechanistic model are correct. The surfaces of coal may have oxygen (O) attached to carbon atoms on the surfaces of the coal (R) in the form RO . The electronegative charge on the oxygen will attract hydrogen ions to form hydroxyl (alcohol) groups (ROH), and cations (such as Na ⁺ and K ⁺ ) to form salt species (i.e. RONa and ROK). The salt species form the principal components of the ash when the coal is burned in air, because these species do not combust. Thus, coals with high ash content may have more salt species than ROH species on their surfaces when compared with coals that produce less ash when they are burned; the H may contribute to one of the combustion products, water, whereas the cations cannot. Coals with high ash contents (up to 30% in some instances) are of lesser value because of the extra transportation costs associated with the extra weight of the ash, for which there is no benefit of energy released during combustion. In addition, burning high-ash coals requires more frequent cleaning of the combustion chamber of ash built-up. Finally, the ash can have a deleterious effect on the walls of the combustion chamber. For example, potassium, K, impregnation of the ceramic walls of blast furnaces can be life limiting. Thus, low-ash coals are favoured in the industry.

[0109] Low-ash coals can be produced with processes that could generally be called Demineralisation [Brooks et al, US 2006/0096166 A1 and references therein]. These processes generally rely on solutions of strong inorganic acids such a sulphuric acid, at very low pH values (0.5 to 1) and usually high temperatures, up to 250°C. The mechanistic model proposed above suggests that for strong acids at lower pH values, the acid protons may displace more of the cations from the surface oxygen atoms into solution. Equilibrium concentrations would be shifted to take protons out of solution to form surface ROH groups, and to put the displaced cations into solution in the form of cation hydroxides, both of which drive the pH to more neutral values and lower the chemical potential. Thus, the cations associated with oxygen on the surfaces of coal may be displaced into solution and replaced with hydrogen atoms in the presence of strong inorganic acids at low pH -the lower the pH the more the equilibrium shifts and the more cations are displaced into solution. Processes using sulphuric acid at pH values below 1, and typically 0.5 or lower, can reduce ash contents to below 0.2% in some coals. The practicality of these demineralisation processes is limited by severe corrosion of the vessels and components used to contain the coal-acid slurry, because at the acid strengths and temperatures required for these processes, alloys are not immune to corrosion. In addition, storage and handling of strong acids like sulphuric acid at these low values of pH pose health and safety hazards that require expensive care. Thus, demineralisation of coal is possible, but not practical for routine operations, mainly because of the strong acidic conditions required to shift the equilibrium far enough to displace sufficient ash to make the processes worthwhile.

[0110] As described in further detail herein, while working to develop a method to pelletize coal fines, methods have now been developed which may use weak organic acids at moderately low pH values to catalyse hydrothermal processes in a mixture of coal fines and biomass. In these studies, ash content in the coal was reduced to levels only seen previously following strong-acid low-pH demineralisation processes, and, as will be discussed in detail below, coincidently, the biomass was converted to a high energy density polymeric solid that coated the coal fines thereby allowing hard pellets to be produced from the coal-biomass mixture.

[0111] In certain embodiments, the hydrothermal-polymer-coal composites may be seen to be coal fines (or other carbonaceous material) coated with the hydrothermal polymer. The hydrothermal polymers form as small spheroids when only biomass is subjected to the hydrothermal process that includes the weak acid catalyst. When coal fines are added to the biomass and the mixture subjected to the weak-acid-catalyzed hydrothermal process, the product retained the angular features of the coal fines particles, with adherent polymers on the particle surfaces, seen as a white coating on the particle shown in Figure 1. This coating only appeared on the coal fines subjected to the weak-acid-catalyzed hydrothermal process when there is added biomass. The hydrothermal-polymer-coal composite looks and feels like the hydrothermal polymer, there is no visual evidence of the coal fines beneath the hydrothermal polymer coat, which provides further evidence that the hydrothermal polymer coats the coal fines.

[0112] Notably, the ash content of the coal cooked with the biomass in the hydrothermal polymerization process was much lower and comparable to the ash contents following much more aggressive demineralization processes. It was unexpected that a weak organic acid at pH 1.2 to 3.0 could demineralize coal to the same extent as a strong inorganic acid at pH lower than 1, but typically pH 0.5. Without wishing to be bound by theory, a proposed mechanistic model is provided for illustrative purposes. However, the invention may be practiced regardless of whether the particulars of the mechanistic model are correct. The -OH hydroxyl groups on the saccharides (sugars) of the biomass feedstock may undergo a dehydration reaction with the ROH groups on the coal surfaces. The result is R-O-C bonds forming between the hydrothermal sugar- based polymeric molecules and the coal surface, plus release of water molecules. Thus, in this proposed model, the coal fines may provide more than nucleation sites for the hydrothermal polymer, they may be chemically bonded to the hydrothermal polymer. Under the mild acid conditions that promote the polymerization reaction, some of the ash-forming cations may be displaced from the RO-cation sites by protons to form ROH sites, the leaving groups being NaOH, or KOH, which may drive the reaction by lowering the effective acid concentration raising the pH. These ROH sites may then participate in subsequent dehydration reactions, producing water, which may drive the reaction because it dilutes the acid, which raises the pH. These subsequent dehydration reactions may contribute, at least in part, to the remarkable result that the ash was reduced to levels only seen before with strong inorganic acids at much lower pH. The strong inorganic acids used in previous demineralization reactions may push the equilibrium to displace the ash-forming cations from the oxygen on the coal surfaces into solution, forming ROH on the surfaces, and bases like NaOH and KOH that tend to neutralize the acidity in solution. Very low pH is typically required to push the equilibrium far enough to displace sufficient cations. These previous demineralization reactions, based on very low pH inorganic mineral acids, may work by pushing an equilibrium reaction. In the proposed model for the present approach, it is not believed to be reliant on such equilibrium reaction. Under mild organic acid conditions, inorganic cations may be displaced into solution and ROH sites produced, as before for the previous demineralization processes, but these ROH sites may react via a dehydration reaction to form ROC bonds between the carbon atoms on the surface of the coal (R) and the carbon atoms in the growing hydrothermal polymer (C). The ROC bonds may effectively block the active oxygen sites on the coal surface and eliminate the equilibrium reaction. In other words, it is believed that ash forming cations, such as Na and K, may be displaced from RO-cation sites by protons, which may then be lost during dehydration reactions with hydroxyl (alcohol) groups on the saccharide molecules of the biomass, such that the active oxygen sites on the coal may be blocked from partaking in any further equilibrium reactions. Thus, the cations may move only into solution, the back reaction to the coal may be blocked. The absence of the back reaction may be a reason a weak organic acid has now been used instead of a strong inorganic acid to similar effect. The advantages of the weak organic acids when compared with the strong inorganic acids may include that they are much less corrosive, and, at the pH values typically used, may pose significantly reduced health and safety hazards. As will be understood, this proposed mechanistic model is provided for illustrative purposes only, and whether or not this model is correct does not in any way interfere with successful operation of the embodiments described herein.

[0113] Nonaka et al (Fuel 90 (2011) 2578-2584) attempted to upgrade a low rank coal by mixing it with woody biomass, and then subjecting the mixture to a hydrothermal treatment, except without organic acid catalyst. They did not see any reduction in ash. The reason may be because the ash-forming cations are not displaced from the RO-cation sites without the organic acid present, and, at the higher pH values used by Nonaka et al (7), higher because of the absence of the organic acid, the dehydration reaction leading to the formation of the hydrothermal polymers may not occur at the coal surfaces, which means the reverse reaction is not blocked. In US patent application publication no. 2014/0054503 (Apparatus and method for upgrading coal), the authors use a hydrothermal treatment to dewater and de-ash low grade coal. In the hydrothermal dewatering process, many of the carboxyl and hydroxyl groups in the coal may be removed as H ₂ 0, CO and C0 ₂ . Removal of these hydrophilic groups may make the coal more hydrophobic, which means water is pushed from the coal, and the coal is said to be dewatered. Dewatering is not the same as dehydration - the former is based on electrostatic repulsion between a surface and a liquid, whereas the latter results from the formation of a chemical bond between two species, releasing water. The hydrophobicity of the dewatered coal enhances its flotation for ash separation, which may be practical if the coal particles are sufficiently small and the ash is chemically separate. The method described in US 2014/0054503 is used for physical separation of ash comprising silicates and sands that sink in flotation cells. The ash removed with the method described in US 2014/0054503 is mainly in the form of particles that are mixed with the coal, and is not the chemically attached ash comprising cations, such as Na and K. The decrease in the ash content reported in US 2014/0054503 was significant, although the overall change was small, from ash values starting around 25% to ash values of around 15% after the process. It is believed accordingly to the proposed model described above that the authors of US 2014/0054503 saw a relatively small reduction in ash because they did not benefit from the added biomass becoming hydrothermal polymers undergoing dehydration reactions and blocking the hydroxyl sites from reverse reactions that would keep the ash-forming cations from returning to the coal surfaces.

[0114] Coal fines do not bind together into hard pellets, so binders are used, such as pitch from petroleum, coal or organic oils that is modified with cross-linking agents such as inorganic hydroxides, or organic agents such as ethylene polyamines (EP0314252A1). These binders are costly and do not have high energy densities so they do not significantly add to the energy content (calorific value) of the coal when the binder-coal mixture is burned. Cross-linkers such as inorganic hydroxides add to the ash content, which degrades the value of the fuel as described above. In addition, these binders are not generally manufactured using carbon considered to be from the carbon cycle (EP0314252A1), which means these binders provide no relief from carbon taxation of fossil-based fuels.

[0115] Preliminary work by the present inventors showed that the product of hydrothermal polymerization (HTP) of biomass may be used to bind coal fines into a pellet. This hydrothermal polymer can be made to be 'sticky' (i.e. to have binding properties) in the manner useful for the purpose of binding, and of high energy density too. However, the amount of hydrothermal polymer to bind the coal fines into pellets of reasonable strength was greater than the amount of coal fines bound in these preliminary studies. This preliminary result was that the contents of the pellets were mainly hydrothermal polymer binder, not coal, which was undesirable for certain applications. Microscopic images of the insides of these pellets showed large regions of hydrothermal polymer without significant coal inclusions, suggesting that lower amounts of binder may be used if the large regions of mainly hydrothermal polymer binder could be reduced. Thus, in subsequent HTP processing, coal fines were added to the biomass and the mixture subjected to a hydrothermal process with a weak organic acid, based on a reasoning that the coal fines would provide nucleation sites for the polymerization process in a way that the extent of the hydrothermal polymer surrounding the coal fines may be controlled. Although this initial reasoning has been modified as described above (i.e. without wishing to be bound by theory, it is now believed that the coal fines may be more than a nucleation site for the hydrothermal polymer, they may be chemically bonded to the hydrothermal polymer), the hydrothermal polymer did surround and coat the coal fines without excessive regions lacking coal content, and provided a coating that facilitated good subsequent pelleting. In summary, regular coal fines typically cannot be made into pellets at any practical temperature and pressure. It was found herein that the polymer on its own was easy to pelletize, and a mixture of polymer and coal fines also can be made into pellets, but the mixture will typically be mostly polymer for the pellets to be strong. It was further identified that a composite of coal fines encased in a polymer shell produced by a hydrothermal dehydration reaction of biomass saccharides with the hydroxyl groups on the coal surfaces may be formed readily into hard pellets, with the polymer acting as an efficient binder such that less binder than coal fines may be used to fabricate a hard pellet. The following examples provide experimental details and results of studies in which embodiments of the compositions, methods, and apparatus described herein were developed and tested. Examples

[0116] Example 1. A sample of coal fines (40 mesh) was analyzed for calorific value and proximate analysis for reference; this was labeled as Sample A. Samples of the coal fines were then subjected to further processing: A sample of coal was cooked at 240°C for 1 hour in an acid catalyst to give Sample B. A sample of the coal was mixed with pine sawdust and cooked at 240°C for 1 hour in an acid catalyst to produce a hydrothermal-polymer-coal composite, labelled as Sample C. The details of the procedure to produce Sample B and Sample C are given below.

[0117] Sample B: 150 grams of coal fines (40 mesh) and 500 ml of 0.04 molar Maleic Acid (pH = 1.7) was combined to form a coal-catalyst slurry that was stirred for 5 minutes to ensure thorough mixing. The slurry was placed in a 1.1 litre pressure vessel and heated to 240°C under saturated steam pressure. The reactor was held at this temperature for 1 hour. The reactor was then allowed to cool to room temperature before opening. The solids were separated from the liquids using vacuum filtration with a Whatman #3 filter paper in a Buchner funnel. The solids were washed with water and oven dried prior to testing for calorific value and proximate analysis.

[0118] Sample C: 150 grams of pine softwood sawdust was combined with 74.8 grams of coal fines (40 mesh) in 500 ml of 0.04 molar Maleic Acid to form a slurry that was stirred for 5 minutes to ensure thorough mixing of the biomass - coal slurry. The slurry was placed in a 1.1 litre pressure vessel and heated to 240°C under saturated steam pressure. The reactor was held at this temperature for 1 hour. The reactor was then allowed to cool to room temperature before opening. The solids were separated from the liquids using vacuum filtration with a Whatman #3 filter paper in a Buchner funnel. The solids were washed with water and oven dried prior to testing for Calorific value and proximate analysis.

[0119] The thermogram of mass loss as a function of temperature is presented in Figure 3 and the proximate analysis is presented in Table 1 for the three samples: coal fines, Sample A; coal fines cooked with acid, Sample B; and a composite material of 35% hydrothermal polymer and 65% coal (by mass) obtained from a mixed cook of coal fines and biomass (pine softwood sawdust), Sample C. The coal fines had an ash content of 19% which was reduced to 15% by acid washing the coal fines in a dilute weak acid, Sample B. Surprisingly, when the coal was cooked with the biomass (pine softwood sawdust) under the same conditions as for Sample B, the ash content of the product was reduced to 2%, Sample C.

Table 1

[0120] Simply mixing the hydrothermally treated coal with 35%, by mass, low-ash (see the ash content in Sample F in Table 2 discussed later) hydrothermal polymer, made without coal, would result in an ash content of 12.4% by simple mass balance analysis. Thus, by using the methods described herein, the ash content in the hydrothermal-polymer-coal composite was reduced to 2%, which means that the ash in the coal component of the composite was reduced to about 17% of its initial value. Simple acid wash only lowered the ash in the coal from 19% to 15%, the difference between Sample A and Sample B, but the method of this patent lowered the ash in the coal from 19% to 3%. With the additional mass of hydrothermal polymer, which is relatively ash free, the total ash for the hydrothermal-polymer-coal composite was 2%. Without wishing to be bound by theory, this result is in accord with the illustrative proposed mechanistic model described above: more ash is displaced with the process to produce Sample C because the hydroxyl groups (ROH) on coal surfaces may undergo dehydration reactions with the hydroxyl groups on the biomass saccharides to form hydrothermal polymers on the coal surfaces, after displacing the ash-forming cations into solution. The hydrothermal polymers may be chemically bound to the coal surfaces and block ash-forming cations from returning to the coal once they leave. This blocking does not occur with acid wash, because there are no hydrothermal polymers without the added biomass and the catalyst.

[0121] The calorific value was determined by bomb calorimetry using a PARR 6200 Bomb calorimeter. The calorific value of the cooked coal fines in sample B had a calorific value of 29.5 MJ/Kg. The hydrothermal-polymer-coal composite had a calorific value of 28.8 MJ/Kg. The hydrothermal polymer was measured to have a calorific value of 27.6 MJ/Kg. Thus, the hydrothermal-polymer-coal composite has a calorific value that is consistent with that expected for a composite mixture of the coal and the hydrothermal polymer.

[0122] Example 2. Eight grams of wood chips were mixed with 4 grams of coal fines in 96 ml of 0.02 M Maleic Acid catalyst. The slurry had a pH of 1.4. The slurry was placed in a 300 ml pressure vessel and heated to 240°C under saturated steam pressure. The reactor was held at this temperature for 1 hour. The reactor was then allowed to cool to room temperature before opening. After washing with water and drying, 6.1 grams of product was obtained. Similar cooks with coal but no biomass found no mass loss for the coal, thus, the mass of the hydrothermal polymer produced when biomass was cooked with coal for this example is calculated to be 2.1 grams; hence, the product of the cook contains 35% hydrothermal polymer and 65% coal, by mass.

[0123] The hydrothermal-polymer-coal composite was then pressed into a hard pellet and the pellet durability was measured by placing it in a square box along with a number of hard plastic disks. The box was then rotated for 300 revolutions over a 5 minute period. The pellet and fragments were then passed through a #10 (2 mm) screen. The remaining fragments were then massed. The pellet durability index (PDI) was computed:

M _f

PDI = — - X 100 (1)

M ₀ where M ₀ is the mass of the pellet pre-tumble, and Mf is the mass of the pellet fragments post tumble. The pellet was found to have a durability of 98%. Thermogravimetric Analysis was used to produce a proximate analysis, which yielded 3.4% moisture, 51% volatiles, 43.6% fixed carbon and 2.0% ash for the pellet.

[0124] A further series of samples were cooked using the method of this example, only varying the amount of input materials to produce hydrothermal-polymer-coal composite pellets that were then tested for durability. The durability of these composite pellets was compared with the durability of pellets that were produced by simply mixing the hydrothermal polymer material with coal fines. The durability for these pellets is plotted in Figure 4.

[0125] The hydrothermal-polymer-coal composite pellets produced by the methods disclosed herein may be significantly more durable than pellets produced by simply mixing the two materials (i.e., the hydrothermal polymer mixed with coal fines) and pressing the mixture. For the mixed material pellets the durability fell below 90% when the mixture was 50% coal and 50% hydrothermal polymer - pellets with less than 50% hydrothermal polymer were easily crumbled, they have durability indices less than 60%. In contrast, the pellets produced by cooking the biomass with the coal fines resulted in much more durable pellets. For example, a pellet made from a composite of 75% coal and 25% hydrothermal polymer had a durability higher that 90%. Durable pellets could be made with much less hydrothermal polymer and much more coal when the hydrothermal-polymer-coal composite was pressed, which may be particularly advantageous for the application of packaging and selling coal fines because it increases the coal loading.

[0126] Example 3. A composite sample of 60% coal fines and 40% hydrothermal polymer was produced by cooking a slurry of coal fines, a biomass material and a 0.02 molar Malic Acid catalyst. The material, after washing with water and drying, was formed into a circular pellet of diameter 0.9 cm and thickness 4 mm. The pellet was subjected to compression normal to the plane of the pellet in an Instron 5582 Material Test System. The pellet was compressed with a force of 5.0 kiloNewtons prior to cracking. Figure 5 shows the curve of stress vs strain for the pellet.

[0127] Example 4. Two samples of hydrothermal-polymer-coal composite material were made by cooking coal fines and ground pine for 1 hour at two temperatures: 220°C (Sample D) and 240°C (Sample E). A third sample which did not contain any coal was cooked at 220°C for 1 hour and is labelled as reference Sample F. The thermogram used to determine the proximate analysis is presented in Figure 6 while the proximate analysis is presented in Table 2. The samples in all cases were processed in a 1.1 litre stainless steel autoclave, the catalyst used was a 40 mM solution of Maleic Acid (pH 1.7) and the procedure was the same as was used in example 1. The samples were allowed to equilibrate with the atmosphere for 24 hours after drying.

[0128] The moisture contents in Table 2 indicate that the hydrothermal-polymer-coal composite was less hydrophobic when cooked at 220°C than at 240°C. The hydrothermal-polymer-coal composite was more hydrophobic than was the hydrothermal polymer by itself, Sample F. Lower moisture contents are desired because it costs money to ship the moisture, but the moisture does not add to the heating value.

Table 2 [0129] A surprising result is that the ash content of the hydrothermal-polymer-coal composite produced at 240°C is less than one half (2.3% vs 5.0%) of the ash content when the composite was processed at 220°C. This result is consistent with the illustrative proposed mechanistic model presented hereinabove. At higher temperatures, the entropy contribution to the free energy may increase for the reaction where the ash-forming cations leave the RO-cation sites on the coal and go into solution. By varying processing variables such as temperature, product attributes such as ash content may be changed in a systematic way. Other process variables may include time and catalyst concentration, and product attributes in addition to ash may include moisture content and energy content, as well as fixed carbon, oxygen and hydrogen contents. [0130] Example 5. Eight grams of wood chips were mixed with 4 grams of coal fines in 96 ml of

0.02 M Phosphoric Acid catalyst. The pH of the slurry was 2.0. The slurry was placed in a 300 ml pressure vessel and heated to 240°C under saturated steam pressure. The reactor was held at this temperature for 1 hour. The reactor was then allowed to cool to room temperature before opening. After washing with water and drying the product of the cook contained 35% hydrothermal polymer and 65% coal. The calorific value was determined by bomb calorimetry using a PARR 6200 Bomb calorimeter: the calorific value of the hydrothermal-polymer-coal composite was determined to be 28.1 MJ/Kg; the coal fines prior to processing had a calorific value of 29.5 MJ/Kg

[0131] Thermographic analysis provided the proximate analysis of the hydrothermal-polymer- coal composite produced with Phosphoric Acid catalyst to be: 3.2% moisture. 52.3% volatiles, 40.8% fixed carbon and 3.8% ash. The ash content of the resulting composite was higher when Phosphoric Acid was used as the catalyst than when Maleic Acid was used as the catalyst (see Example 4, Sample E, where the ash content was measured to be 2.0%). In the case where Phosphoric Acid is used as the catalyst it is hypothesized that some of the Phosphorus binds to the coal oxygen sites as a phosphate, which may then add to the total ash content. The ash content of the hydrothermal-polymer-coal composite was lower (3.8%) than for the same mixture, by mass fraction, of hydrothermal polymer and coal (12.4%), as described in Example 1, hence, the overall ash content of the coal is still reduced.

[0132] An advantage of using Phosphoric Acid may be that it is inexpensive and readily available; although a disadvantage is that using it may add to the ash. Thus, a practitioner of skill in the art may choose to use Phosphoric Acid as catalyst in instances where the concomitant increase in costs associated with the increase in ash is offset by potentially lower costs for the catalyst, for example.

[0133] While a number of exemplary aspects and embodiments have been discussed above, those with skill in the art will recognize certain modifications, permutations, additions and sub combinations thereof. It is therefore intended that the following appended claims and claims hereafter introduced are interpreted to include all such modifications, permutations, additions and sub-combinations as are within their true spirit and scope.

[134] It will be understood that all references hereinabove to ranges of values, or values selected from between a lower limit and an upper limit, or values above a lower limit, or values below an upper limit, are intended to also encompass and describe narrower embodiments, such as any sub-ranges or subsets of values falling within the larger ranges, and any particular integer value, or value rounded to the nearest 0.1, which is found within the larger ranges which are defined. For example, references herein to ranges of pH, pKa, temperature, mass ratios, calorific value, and/or time are intended to also encompass and describe narrower embodiments, such as any sub-ranges or subsets of values falling within the larger ranges, and any particular integer value, or value rounded to the nearest 0.1, which is found within the larger ranges which are defined.