Title:
METHOD FOR PRODUCING HIGH BRIGHTNESS, LOW ABRASION CALCINED KAOLIN PIGMENT
Document Type and Number:
WIPO Patent Application WO1996029294
Kind Code:
A1
Abstract:
A process for preparing a high brightness, low abrasion calcined kaolin. A cretaceous crude (10) is wet beneficiated by subjecting same as an aqueous slurry to degritting, classification (20), magnetic separation (24) and scrub grinding (28). The slurry from the foregoing (30) is diluted to less than 15 % solids and subjected, while well dispersed, to a separation in a centrifuge to yield an underflow and an overflow fine fraction having less than 5 % solids and a P.S.D. such that at least 85 % by weight are of < 0.5 mu m E.S.D. and at least 30 % by weight are of < 0.25 mu m E.S.D. The overflow fine fraction slurry of dispersed kaolin is subjected to a partial filtration by passing same in cross flow relation to a microporous membrane (44) through which substantially none of the suspended kaolin particles pass, to raise the solids content of the slurry to at least 20 %. This slurry is combined with up to 90 % on a dry weight basis of a slurry of a fine particle size tertiary kaolin, and is then blended in a blending tank (49), flocculated and filtered (50) to yield a filter cake, which is redispersed (52), dried (54) and milled (56) to provide a calciner feed. The feed is calcined (58) at temperatures above the kaolin exotherm to yield a calcined product (62) having a brightness of at least 92 and an Einleiner Abrasion less than 24.
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Inventors:
SMITH RANDOLPH O
POPE WILLIAM H
POPE WILLIAM H
Application Number:
PCT/US1996/003569
Publication Date:
September 26, 1996
Filing Date:
March 15, 1996
Export Citation:
Assignee:
ECC INT INC (US)
International Classes:
B03B9/00; C09C1/42; (IPC1-7): C04B33/04; C09C1/42; C09C3/04
Foreign References:
| US5168083A | 1992-12-01 | |||
| US5227349A | 1993-07-13 | |||
| US5137574A | 1992-08-11 | |||
| US5047375A | 1991-09-10 | |||
| US4381948A | 1983-05-03 |
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