Abstract
The use of alumina-containing nepheline raw materials as an alternative source of alumina is relevant in the context of the limited bauxite reserves in Kazakhstan. Nepheline processing can result in products such as alumina, sodium and potassium salts, silicate products and rare metals. In terms of economic value, alumina is the most important. This article considers an advanced technology for nepheline processing for the extraction of alumina that is first purified from potassium. The application of calcium sulphate and calcium oxide as additives to the nepheline raw materials is studied. The optimal conditions for two-stage leaching with calcium additives in the form of calcium sulphate and calcium hydroxide are determined.