New technology for producing hematite concentrate from wastes generated in the processing of iron quartzites

Abstract

Results from studies of the use of reverse cationic flotation and an effective new reagent-based method for the beneficiation of waste products (Fe ~25% and SiO 2 ~54%) formed in processing iron quartzites from the Mihailovskii deposit show that the hematite concentrate which is obtained has an iron content of roughly 60% and contains less than 5% SiO 2 (without preliminary dressing). The use of high-gradient magnetic separation for beneficiation of the same waste products yielded iron concentrate with excellent processing properties. It is found that a technology which combines magnetic separation and flotation is the most promising approach to the concentration of materials that contain hematite. The main iron-ore reserves in Russia are concentrated in the area of the Kursk Magnetic Anomaly (KMA). Seventy percent of the deposits in this region are composed of low-grade finely impregnated ores (iron quartzites with an iron content no greater than 34%) and 30% high-grade ores with an iron content of more than 61% [1]. The main deposits in the KMA are the Lebedinskii and Mikhailovskii deposits, with a combined ore reserve of more than 17 billion tons [2]. The main ore mineral in the Lebedinskii deposit is magnetite and the main non-ore mineral is quartz. Magnetite, kummingtonite-magnetite, and biotite-magnetite minerals are the main minerals in the iron quartzites, which also contain smaller amounts of oxidized and semi-oxidized ores. The ores in the Mikhailovskii deposit differ from those in the Lebedinskii deposit in their broader mineral composition and the greater accretion of ore and non-ore minerals. The deposit consists mainly of hematite-magnetite and magnetite-hematite ores. The technologies for the beneficiation of iron quartzites ‐ particularly wet magnetic separation in a weak field (WMS), which is used at Russian plants ‐ are useful only on magnetite quartzites. Here, the iron losses with the tailings (connected with hematite, which is not extracted by WMS) total more than 1.5‐2.0 million tons a year just a one plant [2]. In light of the fine granulometry associated with opening of the magnetite grains, either mechanical concentration or flotation can be used to extract the hematite in the tailings from this operation. Thus, the problem being examined is to evaluate the efficiency of high-gradient magnetic separation and reverse cationic flotation to concentrate wastes currently being produced in the processing of iron quartzites from the Mikhailovskii deposit. Our specific goal was to obtain iron concentrate with more than 63% Fe and less than 6% SiO 2 while recovering the Fe in a cost-effective manner. Studies were performed on a material containing roughly 25% Fe and 54% SiO 2 . The material was composed of tailings from wet magnetic separation and liquid discharged from magnetic desliming units.