Abstract
Due to limited reserves of bauxite, nepheline can be used in the industrial production of alumina in Kazakhstan. The most promising deposit is the nepheline syenites of the Kubasadyr deposit. Currently, there is no effective technology for processing nepheline ores. High energy intensity, capital intensity and significant emissions into the atmosphere are the main drawbacks of the conventional technology of nepheline ore processing by sintering method. Efficient hydrochemical processing of nepheline requires pre-enrichment with the separation of a part of silica. According to the existing technology of chemical enrichment in an alkaline solution at a temperature of 280⁰С, the silica extraction degree is no more than 36%. A pre-roasting at 500⁰C is used to increase the extraction rate of silica and this process permits an increase in the extraction rate to 65%. The paper presents the results of the chemical activation of nepheline syenites in a solution of sodium hydrogen carbonate. The optimum conditions of activation are determined. Activation at a temperature of 280 ⁰C resulted in a change in the phase composition of the feedstock and increases the degree of silica extraction up to 65,5%. The results obtained showed the possibility in principle of using hydrochemical enrichment technology for the resulting high-quality nepheline concentrate and replacing the energy-intensive roasting process.