Patent ID: 6495511
Filing Date: 2002-12-17
Classification: C11D

Abstract:
A process for treating a bentonite having a montmorillonite content of at least 85% which, when activated with sodium ions dried and ground, does not swell more than about 2.5-fold when gradually added to deionised water at room temperature and when crushed dried and calcined to an LoI of less than 4% at 190Â° C. absorbs 16 to 22% by weight of water in a controlled environment at 25Â° C. and a relative humidity of 40% by weight, which process comprises the following steps in the following order:(i) drying the bentonite to a moisture content from 25 to 35% by weight; (ii) conditioning by crushing, mixing and/or extruding; (iii) addition of water to form an extrudable paste having a moisture content of 25 to 40% by weight; (iv) extrusion through a die preferably from 4 to 10 mm in diameter; (v) drying to a moisture content from 10 to 14% by weight; (vi) calcining at 120 to 250Â° C. to an LoI of less than 4% at 190Â° C.; and (vii) reduction to particles.