INFLUENCE OF ULTRASOUND PROCESSING PARAMETERS ON THE RESIDUAL CONTENT OF CALCIUM SULFATE IN SOLID HALITE WASTES
When mining and processing potassium-magnesium ores, millions of tons of halite waste are formed, occupying huge areas and being environmentally dangerous. The basic useful component of this waste is sodium chloride, which can serve as an excellent raw material for the production of chemical industry products, such as soda ash, sodium hydroxide, sodium metal, hydrochloric acid, sodium sulfate, etc. One of the key problems hampering the wide use of halite waste as a source of sodium chloride is the high content of calcium sulphate. The concentration of this compound in the waste of enterprises engaged in the benefication of potassium-magnesium ores reaches 3% and affects adversely the possibility of their further processing into the target products. The purpose of this paper is to evaluate the influence of parameters of ultrasonic processing the halite suspension on the efficiency of eliminating calcium sulphate. With the use of an ultrasonic laboratory installation IL 100-6 / 1, investigations were carried out for the cleaning of quarry salt and halite dumps of potash ore mines of Uralkali. The experiments performed have resulted in identifying the influence of the liquid and solid phase upon the purification degree of the investigated product. It is shown that the purification degree halite raw material during the ultrasonic treatment substantially increases at a liquid-solid ratio of 5:1. The dependence has been found of the purification process efficiency on the specific acoustic power of ultrasonic action. It is shown that the highest purification degree of halite waste regarding CaSO<sub>4</sub> impurities is achieved when the specific acoustic power is 3.8 W/cm<sup>3</sup> or higher. The mathematical dependences of the residual concentration of calcium sulphate in the studied wastes on the time of exposure and on the specific acoustic power of ultrasonic treatment were established. The regression analysis method revealed the most significant of the analyzed factors, which has the maximum effect on the degree of purification of halite waste from calcium sulfate impurities during the ultrasonic treatment. The potential is shown for using the findings to improve the technology of manufacturing a technical solution of sodium chloride with the use of both the quarry salt and the halite dump coming from the benefication plants of Uralkali.