GB1466185A - Dewatering of slimes - Google Patents

Abstract

1466185 Particulate material for dewatering slimes ANDCO Inc 6 March 1974 [7 March 1973 19 Feb 1974] 10074/74 Headings C1A, C1B C1C and C1N [Also in Division C3] A particulate material comprises solid particles having a size and density such that they are readily separable by gravity from an aqueous medium of a slime, the particles being coated with a polyelectrolyte comprising calcium hydroxide hydrolysed polyacrylamide. The material may be used to dewater the slime by intimately contacting the slime with the particulate material so as to cause the dispersed solid material of the aqueous slime to repel water and adhere to said particulate material so as to form a solid phase which is readily separable from the aqueous medium of the slime. The solids content of the slime may be from 1 to 25% and the solids of the slime have dimensions in the range 0À01 to 150 microns. The particles of the particulate material may have a density of from 1À1 to 2À5 g./ml., and a minimum particle size in the range 200 microns to 4 mm. The particulate material may be sand, flyash, activated carbon, silica, titanium dioxide, alumina, glass, graphite, ground rock, and natural and synthetic polymeric materials which are water insoluble. The polyacrylamide may be up to 40% hydrolysed, with an average molecular weight in the range 100,000 to 15 million, and may be present in an amount of from 0À0001 to 1% by weight of the particles. The slime may be, e.g. a clayey slime, or a slime from phosphate rock. Examples show the use of dewatered slime as a foundry sand, a filler or aggregate for building materials, an agricultural material or a fertilizer. The metal values of metal oxides and hydroxides may be recovered.