BENEFICIATION OF MAGNETITE-HEMATITE ORE BY THICKENING

Abstract

The discrepancy between the quality of the extracted raw materials and the requirements of consumers makes it necessary to have an ore processing cycle in mining and metallurgical processing. 2/3 of the extracted iron ores are subjected to enrichment. The most widely used methods of iron ore processing are: gravity, magnetic, flotation, special, combined. Thickening is commonly used to remove excess moisture during mineral processing, particularly iron-bearing ores. However, our study shows the possibility of using thickening as the main method of enrichment. In laboratory conditions, it was possible to obtain iron content in the concentrate – 63.1% (Fe₂O₃ – 90.33%) at the content in the initial ore – 57% (Fe₂O₃ – 81.53%). The productivity of the thickening process is determined by the density of particles and medium, dynamic viscosity of the pulp, but is largely determined by the particle size: the larger the particle size, the higher the sedimentation rate. The carried out granulometric analysis of ore showed that the maximum content of iron oxide is characterised by the fraction – 71 microns. Calculated rates (according to Stokes law for laminar sedimentation) for hematite and magnetite were 0.011 m/s, goethite and siderite – 0.008 m/s, quartz, kaolinite – 0.004 m/s and wollastonite – 0.005 m/s. The particle diameter was 70∙10^–6 metres. The concentrate yield was 88.2% and the iron recovery efficiency of the concentrate was 97.7%. To calculate a more accurate ore sample, the true density of the ore itself and its fractions was determined. On average, the ratio between bulk and true density for ore fractions ranged from 0.57 to 0.70, while for the bulk sample, the ratio was 0.60. An experiment on extracting iron oxide from the +1 mm fraction with grinding to –0.3 mm showed the possibility of increasing the Fe₂O₃ content to 89.5%.