Maksimov I. I., Science Director; Sentemova V. A., Leading Researcher; Akkerman Yu. E., Leading Researcher, office@mekhanobr.spb.ru, JSC «Mekhanobr Engineering» (Russia).

The article considers the issues pertaining to high-grade iron concentrates production from oxidized iron ores that are currently being mined together with magnetite ores, and dumped into special waste piles. Oxidized iron ores are distinguished by a variety of textural and structural specialties, complex intergrowths of magnetite and hematite, development of very fine magnetite and hematite in quartz, siderite and mica, presence of high-ferruginous green mica (celadonite) and ferruginous carbonate (siderite). The studied ores contained 40.6 % iron, 4.6 % FeO and 52.9 % Fe₂O₃. The task of the performed research consisted in development of flow sheet for production of concentrates with iron content at least 66 % from oxidized ores, using energy-saving technology. For this purpose, expenditures of energy were determined in applications of cone crushers, autogenous grinding and semiautogenous grinding operations, and also high-pressure grinding rolls. Most significant saving of energy was achieved in final crushing stages products re-crushing by means of high-pressure rolls. In magnetic separation studies of feed ore ground to 95 % of –44 micron size with induction of 0.08 T, magnetite concentrates with 66 % iron content were produced, and with induction of 0.11 T — hematite concentrates with iron content within 62.7 %. Three alternative methods for the feed ore and magnetic separation concentrates processing by means of flotation with application of cationic collectors in alkaline medium have been developed. Lilaflot and РА-14 collectors, medium regulator — caustic soda, depressor of iron minerals — dextrin are recommended for flotation. Two-stage magnetic-flotation flow sheet is proposed for oxidized iron ores processing. Concentrates with iron content over 66 % were produced, iron recovery into concentrate being 72.4–72.9 %. Energy-saving in the recommended flow sheet was achieved by means of two-stage magnetic separation at 200 and 44 microns size, as well as through improvement of ore-preparation flow sheet with re-crushing on high-pressure rolls prior to grinding.

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