Improvements in the industrial treatment of leucite, or of aluminous potassic and sodic silicates, or of natural and artificial alums, for the purpose of obtaining pure alumina, compounds, of potassium, or sodium and silica

摘要

354,255. Electrolysis. GALLO, G., of R. Scuola d'Ingegneria, Istituto di Chimica, Pisa, Italy. May 1, 1930, No. 13505. [Class 41.] A solution of double sulphate of sodium or potassium and aluminium preferably containing an excess of alkali metal sulphate is electrolyzed in a divided cell to obtain sulphuric acid at the anode and sodium or potassium aluminate at the cathode. Oxygen and hydrogen may be simultaneously produced. The electrolyte may be obtained from natural or artificial alums or by treating leucite or similar minerals with sulphuric acid,. silica being in this case obtained as a by-product. The catholyte which may contain hydroxides of iron, calcium, and magnesium in suspension is filtered and treated with carbon dioxide for the preagitation of aluminium hydroxide. The anolyte containing sulphuric acid is used for treating fresh material. A lead anode and an iron cathode, and a diaphragm of rubber or porcelain are employed. The double sulphate solution may be passed in succession through the anode compartments of a set of cells, a dilute solution of sodium or potassium sulphate being passed through the cathode compartments in the opposite direction. When three compartment cells are employed, dilute sulphuric acid is passed through the anode compartments, dilute sodium or potassium sulphate solution in the same direction through the cathode compartments, and the double sulphate solution in the opposite direction through the centre compartments.