SUMMARY
There are three main types of industrial iron ores in Kryvyi Rih basin: rich ore that are directly used in metallurgy, magnetite ore and oxidized ferruginous quartzites that need enrichment. Deposits of rich ore are depleted. Nowadays, ferruginous quartzites are the main part of all deposits of Kryvyi Rih basin. Main commercial significance of ferruginous quartzites belongs to unoxidized magnetite and magnetite-hematite types but their reserves are nearly exhausted. But, there are large reserves of oxidized iron ore available in Kryvyi Rih basin that could be used as raw material for concentrates’ production. It is known that production of iron ore concentrates from poor oxidized iron ores related with various problems. Processes of transformation were studied for three types of iron ores: hematite ore, oxidized hematite ore (two samples) and hematite-goethite ore from deposits of Kryvyi Rih. Transformation of hematite and goethite, which are main mineral components of iron ore, to magnetite by heating to temperature of 98°? in aqueous Fe+2-containing medium under microwave radiation was investigated. Phase composition of initial samples was determined by X-ray diffraction (XRD). It was shown by XRD method that hematite ore consists of quartz and hematite, oxidized hematite ores consist of hematite and kaolinite and hematite-goethite ore consists of hematite, goethite and quartz. It was shown by XRD method that, after transformation in all obtained samples appears a phase of magnetite. Saturation magnetization of initial and obtained samples was investigated by magnetometry method. Saturation magnetization of initial samples was < 1 ?·m2/?g. Saturation magnetization of obtained samples was within the range 8-30 A·m2/kg. Possible mechanisms of hematite and goethite transformation to magnetite have been described. The results could be used for the development of effective techniques of iron ores enrichment for ore concentrates creation.