Beneficiating kaolin clay by subjecting to selective rheological sepn.

摘要

In beneficiating a Kaolin clay to improve the high shear viscosity of a high solids suspension formed from the beneficiated prod., a 10-20 wt.% solids aq. suspension of the clay is subjected to a selective rheological separation by mixing the suspension with 0.001-0.1 wt.% (on dry clay) of a high mol. wt. anonc polyacrylamide or deriv.. Aggregates of minute Kaolin platelets are selectively flocculated and the treated suspension s allowed to separate into a sedimented phase contg. a clay fraction of high high-shear viscosity characteristics and into a supernatant phase free of aggregates contg. in suspension a fraction (I) of clay pigment possessing low high-shear viscosity props. The supernatant phase is sepd. to recover in suspension, the Kaolin fraction EPAB- EP--66611 B A method of treating a kaolin clay containing less than 0.8% by weight of titania so as to obtain a fraction having a value of high-shear viscosity in a high-solids suspension which is low relative to the starting clay, thereby being desirable for use in coating of paper, said method comprising the steps of forming said kaolin clay into a dilute aqueous suspension having from 10% to 20% solids by weight; mixing said suspension with from about 0.001% to 0.1% by weight, based on the weight of dry clay, of a high molecular weight anionic polycarlamide polymer or derivative thereof to selectively flocculate aggregates of minute kaolin platelets, and allowing the thereby treated suspension to separate into a sedimented phase containing a clay fraction of relatively high high-shear viscosity characteristics and into a supernatant phase which is substantially free of aggregates and which contains in suspension a fraction of said clay pigment possessing relatively low high-shear viscosity properties; and separating the supernatant phase to recover in suspension the said kaolin fraction displaying said low high-shear viscosity properties. (24pp)