GB460410A - Improvements in and relating to the treatment of silicate ores - Google Patents

Abstract

Silicate ores containing, besides silica, one or more amphoteric metal oxides such as zirconium, titanium, aluminium, iron, or chromium oxide, and more particularly ores of zirconium, thorium, or beryllium are calcined with a barium compound such as barium carbonate in such amount that the silica is converted to dibarium silicate and one or more of the amphoteric metals to the barium salt thereof, fluxing additions or an excess of barium carbonate which would tend to fuse the mixture at the operating temperature of say 1400 DEG C. being avoided. Reaction may be effected in a rotary or tunnel furnace, the ore and barium carbonate being briquetted in the latter case. In the case of zircon, a mixture of dibarium silicate and barium metazirconate is obtained which may be used as a refractory. Or the mixture may be crushed with hot water to form and remove barium hydroxide and leave a mixture of monobarium silicate and barium metazirconate, the latter mixture being treated either with hot sodium or potassium carbonate solution to form and remove sodium or potassium silicate, or first with carbon dioxide to form silicic acid, and then with caustic soda to form and remove sodium silicate. In either case a mixture of barium carbonate and metazirconate remains, which may be calcined at 1400--1500 DEG C. to obtain a refractory consisting of barium orthozirconate, and the latter, if desired, may be reheated with zirconium oxide to obtain a refractory consisting of the metazirconate. The products contain barium titanate and ferrate, and a small amount of lime and magnesia, if these bases are present in the ore. In a modification, the barium carbonate-metazirconate mixture may be treated with hydrochloric acid to obtain a solution of zirconium and barium chlorides, the solution be first treated with ammonia to precipitate zirconium hydroxide which is calcined to the oxide to obtain a refractory containing a little titanium and iron, and then with carbon dioxide to precipitate barium carbonate which may be re-used; or the solution may be added to sulphuric acid, gypsum, or a soluble sulphate to precipitate barium sulphate, and the zirconium then be precipitated by lime.ALSO:Zirconium silicate ore (zircon) is calcined at 1400 DEG C. with a barium compound such as barium carbonate to obtain a refractory comprising a mixture of dibarium silicate and barium metazirconate. The mixture may be crushed with hot water to obtain a mixture of monobarium silicate and barium metazirconate, from which by removing silica as alkali silicate by means of alkali carbonate a mixture of barium carbonate and metazirconate may be obtained. The latter mixture may be calcined at 1400-1500 DEG C. to obtain a refractory consisting of barium orthozirconate, and the latter, if desired, may be reheated with zirconium oxide to obtain a refractory consisting of the metazirconate. The products contain barium titanate and ferrate, and a small amount of lime and magnesia, if these bases are present in the ore.