Study On Reverse Flotation Process Technology For Preparing Schoenite

China is a large agricultural country and about60%of the arable land is lack of potassium. The annual demand of potash fertilizer for agricultural production is about10million tons and more than6million tons are needed to import. Due to the serious shortage of potassium resource, the potash fertilizers in our country rely heavily on import, which has an influence on the safety of grain production. With regard to the utilization of potassium resources, the soluble solid potassium salt and salt lake brine are dominated. The proven reserves of potassium resources in China are only2%of the world total, and they are mainly distributed in Qinghai and Xinjiang in the form of salt lake brine. Therefore, the scientific exploitation and rational use of potassium resources have always been the key research contents.Schoenite (K2SO4MgSO4·6H2O) is an important kind of potash fertilizer. So far, the principal methods for the preparation of schoenite are two-step transition method and transition-flotation method. And the main domestic producers are Qinghai CITIC Guoan technology development Co., Ltd. and SDIC Xinjiang Lop Nor potassium salt company. It has been demonstrated by the production practice that the traditional production process has long process line, large equipment investment and high energy consumption.In this paper, experiments were conducted by studying the extraction of schoenite from the mixed salt of potassium-magnesium in sulfate typed of saline lake brine by reverse flotation technology. The major experiments performed in this work are the optimized experiments of reverse flotation reagents, the study of mineral particle size, etc. Based on the results of the above study, the ratio of flotation medium components, the operating temperature, flotation operation in the extreme conditions, and the purification of schoenite are studied one by one. Finally, amplified test and evaluation are performed according to the results of laboratory study.Experimental results show that alkylmorpholine flotation reagents are suitable for the flotation separation of schoenite from the mixed salt of potassium-magnesium in sulfate typed of saline lake brine. It has many advantages, for example, high efficiency of removal for sodium, high-usage of potassium resource, little reagent consumption, and low reagent cost. The flotation reagent dosage is450g·T-1～500g·T-1.The optimized flotation conditions are:the particle size smaller than40#, the mass ratio of SO42-to K+being about2.5, the concentration of flotation slurry being controlled at30%～40%, and the concentration of magnesium ion in flotation medium being45g·L-1～60g·L-1. Based on that the change of key factors of flotation temperature can significantly affect the yield of K+, it is suggested that the low concentration of slurry and flotation medium or insulation measures should be adopted when the temperature is low. The purification of schoenite is realized by adding water into the soft leonite. The coefficient of adding water is0.4and the transition temperature is higher than15℃.Through experimental study on the whole process, the yield of the total potassium ion reaches to74.56%, which is higher than that obtained though the traditional technology of positive flotation method and two stage conversion method.According to the results of amplified test in industry, the reversed flotation method studied in this work is better than the positive flotation method (i.e., transition before flotation technique), for example, short process flow, low cost of equipment investment, decreasing the energy consumption, as well as improving the recovery rate of potassium, so it has a better industrial application prospect.