STUDY OF ALUMINUM EXTRACTION AND IRON REMOVAL FROM KAOLIN CLAYS USING TWO-STAGE TREATMENT WITH SULPHURIC ACID

This paper presents the results of research on the treatment of kaolin clay with sulfuric acid of various concentrations. The goal of the initial stage of research was to determine the optimal conditions affecting the iron removal process. The degree of extraction of Fe, Al, Si in solution was determined from solid samples obtained during the leaching process using X-ray phase analysis (XRD), IR spectroscopy, thermal, and also from the results of EDS analyses. The results show that processing clay with a 5% solution of sulfuric acid in an autoclave at a temperature of 125-130º C, at a pressure of 4-5 atm, for 0.5-1.0 hours, or at a temperature of 85-90º C, for 5 hours purifies iron up to 96-99%. Kaolin clay separated from iron was mixed with 95% sulfuric acid and thermally treated at a temperature of 250º C for 2 days, after which the sulfated mass was dissolved in water at a temperature of 80-90º C in the ratio S:L = 1:5. The resulting mixture was filtered and the sulfate solution was evaporated to a density of 1.4-1.5 g/sm3. In this case, pure salt Al2(SO4)3∙nH2O precipitates in the crystallizer