US Patent 7875188 Treatment of aqueous suspensions

A process in which a suspension comprising dispersed particulate material in an aqueous medium is transferred as a fluid to a deposition area, then allowed to stand and rigidify, and in which rigidification is improved whilst retaining the fluidity of the suspension during transfer, by combining with the suspension during transfer a rigidifying amount of a treatment system which comprises i) a water-soluble synthetic polymer and ii) a water-soluble natural or seminatural polymer. Improved rigidification can be achieved, including dose efficiency especially in regard to the amount of synthetic polymer required. In addition improvements in the clarity of liquor released from the suspension can be achieved.