REC «Mekhanobr-Tekhnika» (St. Petersburg, Russia):

Arsentyev V. A., Research and Development Director, Doctor of Engineering Sciences, ava@npk-mt.spb.ru
Gerasimov A. M., Researcher, Candidate of Engineering Sciences, gerasimov_am@npk-mt.spb.ru

St. Petersburg Mining University (St. Petersburg, Russia):
Kotova E. L., Senior Researcher, Candidate of Geological and Mineralogical Sciences, kotova_elena@spmi.ru

The existing methods of sylvinite ore processing, especially with increased content of water-insoluble fraction, are based on fine grinding of all treated ore, desliming, flotation and dewatering. The investigations performed with a view to develop dry methods of potash ores processing are described in the published literature. However, practically all proposed dry processing technologies demand preliminary thermal treatment. The results of the investigation performed with a view to reveal structural and chemical changes in sylvinite ore components, affecting processing behavior in beneficiation, as well as to search the ways to reduce thermochemical modification costs, are presented. The tests were conducted on abraum salts from the Verkhnekamskoye field (Perm Territory). Taking into consideration that water-insoluble fractions content in sylvinite ore is 3–6 %, an attempt was made to heat the ore in such a way that water-insol-uble fraction would be mainly heated, with minimal heating of salt minerals — halite and sylvite. Super high frequency (SHF) thermal treatment was applied. The obtained data show that water-insoluble fractions SHF heating rate significantly exceeds the heating rate and the temperatures achieved on salt minerals. In order to estimate the changes in sylvinite ore processing behavior following SHF heating, experiments were performed on settling in water the water-insoluble fraction, extracted from ore, and also sylvinite ore flotation tests were conducted. It was established that sylvinite ore thermal treatment in the range of 100–500 °С insignificantly affects halite and sylvite structure, but significantly changes the structure of minerals in water-insoluble fraction, thus influencing upon processing behavior of sylvinite ores. In order to decrease energy costs in thermal treatment, SHF heating was proposed with a view to provide selective heating of minerals in water-insoluble fraction. It has been shown that with SHF heating, the changes in sylvinite ore processing behavior are similar to those observed with convective heating.
The studies were performed with the aid of the Russian Science Foundation Grant (Project No. 15-17-30015).

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