Abstract: A process for alunite ore treatment which comprises roasting alunite in the presence of oxygen at a temperature of from 580.degree. to 620.degree. C. for 1 to 3 hours, decomposing the roasted alunite by exposure to reducing agents at a temperature of from 580.degree. to 620.degree. C., subjecting the reduced alunite to hydrochemical treatment by use of a sodium hydroxide solution of concentration from 100 to 150 g/lit in terms of Na.sub.2 O, decomposing the resultant aluminate liquor, with the aluminum hydroxide component precipitating out, and finally, washing and baking the aluminum hydroxide precipitate to obtain same as an end product. The invention provides a comprehensive method of treatment of alunite ores the associated rock whereof comprises silica in the form of opal and chalcedony earlier believed to be refractory to comprehensive treatment by alkaline methods.

Abstract: The invention relates to methods of preparing vanadium pentoxide from a vanadium-containing solution, and more particularly, from a sodium vanadate solution. The method consists in that the solution is treated at a pH of 4 to 6 with ammonium chloride or sulphate to prepare an ammonium-vandate salt precipitate which is then dissolved in hot water, and recrystallized by a mineral acid. The new precipitate of the ammonium-vanadate salt is calcined to prepare vanadium pentoxide. The advantage of the proposed method is a highly increased degree of precipitation of the ammonium-vanadate salt from the solution of sodium vanadate and a corresponding decrease of vanadium loss with wastes to at least four times.

Abstract: A plant, comprising apparatus for sequential fluidized bed roasting, reducing and cooling of powdered alunite, mounted on a support and communicating with devices for supplying gas into each apparatus and with cyclones for trapping powdered alunite from flue gases and returning it into said apparatus. According to the invention, built-in the plant in front of the apparatus for roasting alunite, is a shaft heat exchanger having at least one throat subdividing its interior in height into a top and bottom chamber with the ratio of the passage cross-sectional areas of the wide and narrow parts falling within a range of from 2 to 12. The top chamber of the shaft heat exchanger communicates with a cyclone heat exchanger via a supply pipe to which is connected an initial alunite feeder and a cyclone, the bottom chamber of the shaft heat exchanger being in communication with a means for producing flue gases and a pipe discharging gas from the apparatus for reducing alunite though a cyclone.

Abstract: The method of preparing a coagulant for purification of water from mechanical admixtures consists in that alunite is roasted at a temperature of 520.degree.-620.degree. C. The roasted alunite is leached with a 20-35 per cent aqueous solution of sulphuric acid taken in the quantity of 70-90 per cent of the stoichiometrically required quantity, at a temperature of 80.degree.-100.degree. C. After leaching, roasted alunite is added in the quantity of 10-15 per cent of the weight of the starting alunite. The resultant pulp consists of solid and liquid phases, the liquid phase being an aqueous solution of the end product, while the solid phase is an insoluble residue. The solution is separated from the insoluble residue and the end product is finally isolated from the solution.

Abstract: A method for processing alunite consisting in that alunite ore is treated with a solution of caustic alkalis at a maximum temperature of 60.degree.C, and a solid residue resulting from the above operation and containing largely potassium and sodium sulphates, is washed with hot water. As a result, potassium and sodium sulphates are dissolved in the wash water, and potassium sulphate is isolated by the action of a caustic-potash solution. The method enables losses of alkalis and aluminium during processing alunite ores containing active forms of silicon compounds to be much reduced, which compound when treating alunite ores with a solution of caustic alkalis, are liable to form insoluble aluminosilicates which are discarded into slime and thus lost together therewith when the latter is separated from the process solution.

Abstract: The specific feature of the present method is that in the process solution resulting in the processing of alunite with the object of producing alumina and potassium sulphate therefrom, an excess amount of sodium ions is maintained with respect to the potassium ions.The method is advantageous in that it ensures a higher yield of potassium sulphate and a lower contamination of the final products with respect to sodium and potassium ions.