Oxidized quartzite of the Kryvyi Rih region consist mainly of iron oxides, such as hematite and goethite, in addition to quartz. The separation of hematite and quartz is quite complicated process due to similar properties of these minerals. The transformation of weakly magnetic minerals into magnetite is one of the possible solution to this problem. In the present paper, the processes of transformation were studied for four types of iron ores: goethite ore of the Kerch basin, goethite ore of the Kryvyi Rih basin, hematite ore of the Kryvyi Rih basin and hematite concentrate of the Kryvyi Rih basin. We per-formed the transformation of hematite and goethite to magnetite by heating to a temperature of 98 degrees C in aqueous Fe2+-contai-ning solution. Phase composition of initial samples was determined by X-ray diffraction (XRD). It was shown by XRD method that first sample was mixture of goethite and nontronite, second was mixture of quartz, hematite, kaolinite and goethite and the third and fourth one were mixture of hematite and quartz. Saturation magnetization of initial and obtained samples was investigated by magnetometry method. Saturation magnetization for four initial samples was <1 A.m(2)/kg. Saturation magnetization of obtained samples was within 5-14 A.m(2)/kg. Curie temperature of obtained samples was determined by thermomagnetic analysis. By the data of thermomagnetic analysis, it was shown that Curie temperature is close to Curie temperature of magnetite. Possible mechanisms of hematite and goethite transformation to magnetite have been described. According to these mechanisms, magnetite phase is formed by the addition of Fe2+ to weakly magnetic phase. The electron exchange between Fe2+ and Fe3+ occurs in solution. Fe2+ ions adsorb at the surface of minerals and transfer electrons into the bulk crystal. The electrons migrate to edge sites, where they convert Fe3+ ions of the bulk crystal surface into Fe2+ species. The results could be used for the development of effective techniques of iron ores enrichment for ore concentrates creation.
