Major kaolin processing developments |
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| Authors: | Haydn H Murray |
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| Institution: | Department of Geology, Indiana University, Bloomington, Ind. 47405 U.S.A. |
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| Abstract: | The kaolin industry has shown a phenomenal growth record from 1930 to the present and there is no indication that this growth will not continue. Innovative and efficient process developments enabled the kaolin industry to wet process over 5,000,000 tons in 1978 in Georgia and over 3,000,000 tons in the Cornwall district of southwestern England. These two regions supply the major tonnage of paper coating clays for the world's paper industry. The more important process developments are listed as follows: (1) development of chemicals for dispersion and flocculation; (2) continuous blungers to slurry the kaolin at the mine; (3) (continuous degritting by rake classifiers and hydrocyclones; (4) transport of kaolin slurry through pipelines from mine to plant; (5) continuous centrifuges for particle separation into coarse, medium, and fine sizes (6) chemical leaching of iron to improve brightness and color, (7) dewatering to high solids by: (a) continuous rotary vacuum filters; (b) automated plate and frame filter presses; (c) tube presses; (d) high speed contrifuges; (8) spray drying to low moisture and spherical shape to permit bulk hopper car shipments; (9) flotation to remove iron and titanium impurities to improve brightness and whiteness; (10) slurry clay shipments at 70 percent solids in tank cars; (11) high gradient magnetic separation to improve brightness and whiteness and to utilize marginal deposits; (12) delamination to utilize course kaolin stacks to make an improved product; (13) pugging and working the kaolin to improve viscosity; (14) a new development — dewatering to 80 to 85 percent solids using electrophoresis.Each of these developments is described and the future need to develop an efficient process to significantly lower the viscosity of high viscosity kaolins is discussed. |
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