GB632076A - Method and plants for obtaining precipitates easy to separate from the liquid medium - Google Patents

Abstract

In the formation of a precipitate by reacting a solution with a solid, liquid or gaseous reagent by a process such that the reagent is directly and readily soluble, i.e. without chemical transformation, in the reaction medium and thereafter is able to react directly with the solution to form the precipitate, both the reacting substances are introduced progressively and at every moment approximately in the proportion required for the reaction with constant stirring into an empty or partially empty vessel (which may contain a quantity of precipitate from a preceding reaction) until the vessel is full; or are introduced in the same manner into each of a plurality of such vessels inter-connected one with the other so that the precipitates flow successively from p one to the other, in order to obtain a dense precipitate adapted to be easily separated from the residual liquid medium. A chemically insert liquid or a part of the mother liquor from a preceding operation or from the operation in progress or the resulting precipitate may be added to dilute the reacting ingredients. Examples describe the precipitation of barium sulphate by reacting solutions of sodium sulphate and barium chloride, the precipitation of magnesia by the action of lime-water or sea-water, and the precipitation of alumina by the action of carbon dioxide on a cold solution of sodium aluminate.