Improvement of particle size distribution in machine mining of potassium ore

Abstract

The article addresses issues connected with mining and processing of potassium ore. Domesticmanufacture heading-and-winning machines Ural equipped with planetary cutter heads produce sickleshaped cuttings, which conditions a high content of non-processible dust particles –0.25 mm in size. Flotation of such ore increases the mass fraction of -0.25 mm size particles by 1 %, which reduces recovery of the useful component from potassium ore by 0.1 % and decreases the annual profit of the mine by hundreds of millions of rubles. It is required to develop engineering solutions aimed to improve quality of particle size distribution in machine mining of potassium ore. The methodology of calculating planetary disc cutter parameters of heading–and-winning machines Ural is described. It is proved that parameters of cuts made planetary discs of the last machine model Ural-20R fall beyond the rational ranges. A planetary cutter head creates a cross-hatch of cuts on the face. In potash mining, the induced micro-cracks and stress localization areas, which are generated in intersection of cuts, can help reduce the amount of dust sizes in potassium ore by 25–30% if series cleavages of stable geometry are created in a cut. This article proposes the design of a planetary cutter head with differently oriented rotation of rotary cutting discs for a heading-and-winning machine to implement a promising cross-hatch fracture mode in potash mining.