Yara Engineering Corporation

Peter Economou

Thomas D Thompson

John F Gergel

A stable calcined clay slurry and method of preparing the same are provided by adding to a calcined clay suspension containing at least 50% clay in aqueous medium about 0.30% to 0.49% by weight of anionic polymer and about 0.007% to 0.011% by weight of cationic polymer by weight in the slurry.

Stable clay slurries

Kaolin (clay) platelets in water are flocculated with an acid (pH 3.0) to form 'structured agglomerates', which are stabilized by reacting with an urea-formaldehyde prepolymer. The urea-formaldehyde prepolymer forms polymeric agglomerated particles when it comes in contact with the catalytic, acidic kaolin 'structured agglomerates.' The urea-formaldehyde polymeric agglomerated particles cause adhesion or stabilizing of the structured kaolin agglomerates to form a three-dimensional network of 'open structure' with a large number of microvoids (pores). The urea-formaldehyde polymer in the stabilized product varies from 5 to 95% by weight based on the total weight of the final product. The size of the primary particles of the urea-formaldehyde polymer is from 0.1 to 0.7.mu. (micron). The size of the kaolin platelets is from 0.1 to 10.mu. (microns). The structured agglomerates of kaolin-urea-formaldehyde possess a size ranging from 0.25 to 40.mu. (microns).

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Millington, NJ, United States of America

Peter Economou