STUDY OF THE TECHNOLOGY FOR OBTAINING A MIXTURE OF SILICOFLUORIDE AND SODIUM FLUORIDE FROM A BY-PRODUCT OF HYDROFLUORIC ACID PRODUCTION

Abstract

The article presents the results of research on the technology of processing and utilization of by-product of hydrofluoric acid production – a mixture of fluorosilicic and hydrofluoric acids using sodium hydroxide and sodium chloride (local mineral raw materials) to obtain fluoride salts – a mixture of silicofluoride and sodium fluoride. As a result of laboratory studies, the optimal parameters of the process of acid mixture processing using sodium hydroxide and sodium chloride to obtain a mixture of SSF and sodium fluoride were determined: temperature – 20-25 °C, duration – 10-20 min, concentration of sodium hydroxide and sodium chloride – 20-25%; in this case the maximum degree of extraction of SSF and sodium fluoride is achieved. The product obtained when sodium hydroxide was used under these optimum conditions was chemically analyzed and found to consist of 67.8% Na2SiF6 and 31.5% NaF. In the case of sodium chloride, the resulting mixture contains 95.8% of Na2SiF6 and 3.5% of NaF. To confirm the reliability of the results of chemical analysis and the found optimal parameters, as well as to determine the mineralogical composition of the obtained fluoride salts, X-ray phase analysis was carried out using an upgraded Dron-2 unit. The obtained product can be used in electrolysis production for obtaining aluminosilicon alloy (silumin) and electrolyte melt, as well as for fluoridation of drinking water and in the production of acid-resistant cements. On the basis of the conducted laboratory studies, the basic technological scheme of processing of the mixture of FSA and hydrofluoric acid with the use of sodium hydroxide and sodium chloride was developed.