Abstract: A method of producing a dispersed aqueous suspension of an inorganic particulate material which includes the steps of (a) preparing an aqueous suspension of calcium carbonate particles having a particle size distribution such that at least 35% by weight have an esd less than 24 .mu.m, the solids concentration of the suspension being no more than 40% by dry weight; (b) concentrating the suspension by dewatering to increase the solids content to at least 60% by dry weight; and (c) adding a dispersing agent to the concentrated suspension to disperse the calcium carbonate particles and characterized in that the suspension produced by step (c) is pumpable and flowable, the dispersing agent comprising a water soluble copolymer of acrylic acid and maleic acid or a salt thereof having a molar ratio of acrylic acid units to maleic acid units of from 0.5:1 to 10:1 and a mass average molecular mass of from 1,000 to 100,000.

Abstract: A method of producing an aqueous suspension of calcium hydroxide which comprises passing a gaseous flow incorporating particles of calcium carbonate through a calcining furnace thermally to decompose the calcium carbonate, delivering a flow of the decomposition products formed in the furnace comprising calcium oxide particles suspended in gas comprising carbon dioxide to a vessel wherein the calcium oxide particles are contacted with water to produce an aqueous suspension of calcium hydroxide and separating the aqueous suspension from the said gas.

Abstract: A method of treating a dilute aqueous suspension of solid particulate material comprising waste material from a process for recovering petroleum from oil sand includes diluting the suspension with at least 75% of its own volume of water thereby to increase the settling rate of the particulate material and allowing the particulate material to settle to form a concentrated solid sediment. The treated suspension may have been obtained from a process in which an alkaline solution is used to treat the oil sand. The water from which the concentrated solid sediment is separated may be returned to the process for recovering petroleum from oil sand. The solid sediment may be transferred to a separation vessel in which it is fractionated into a coarse particle fraction and a fine particle fraction. The fine particle fraction may comprise essentially particles having an equivalent spherical diameter not greater than 3 .mu.m. The concentrated solid material recovered may be calcined to form a pozzolanic material.