Production of hematite concentrate from hematite-magnetite ore

The main useful minerals in composition of hematite-magnetite ore are magnetite and hematite. Magnetite is extracted by wet magnetic separation in weak magnetic field with production of magnetite concentrate and nonmagnetic product. The nonmagnetic product is a feed of the processing circuit for hematite. It is difficult to produce concentrate with iron content of 58-60 mass % if hematite grains are smaller than 0.05 mm. For hematite concentrate production from finely disseminated hematite-magnetite ore, the magnetic-gravitation and magnetic- flotation circuits are designed. This article discusses the magnetic-gravitational separation circuit for hematite grains smaller than 0.05 mm. The first stage of this circuit is fine screening intended to remove large particles. The second stage is high-gradient magnetic separation. The high-gradient separator performance depends on the mineral composition of initial ore and on the rate of mineral dissociation. In finely disseminated hematite-magnetite ore, the associate minerals are mainly represented by quart and amphiboles. Magnetic properties of hematite and amphiboles are similar. For this reason, the high-gradient magnetic separation product contained hematite, amphiboles and quartz-magnetic accretions. The iron content of the magnetic product was 28.9 %. Thus, additional treatment is required, and separation by gravity is applicable in this case. The gravitational separation was carried out on centrifugal concentrator, jigging machine, spiral separator and sluice, and on concentration table. The best results are obtained on the concentration table. The iron content of the final concentrate was 62.3 %.