Thermomagnetic Enrichment and Dephosphorization of Brown Iron Ore and Concentrates

Resumo

Oolitic brown iron ores are of great economic importance because of the vast reserves that exist in the world. However, their high phosphorus content has limited their use in metallurgy. Exciting enrichment methods are essentially unable to decrease the phosphorus content in such ore, since the phosphorus is present in embedded form as emulsions, without forming independent mineral phases. Hence, there has been very little use of such ore. With the increase in global steel production today, demand for iron ore is rising. Accordingly, considerable efforts have been made to create new systems for phosphor removal from brown iron ores, so as to obtain conditioned concentrates. Kazkhstan’s shortage of iron ores that are already rich or readily enriched calls for the utilization of the enormous reserves of easily mined oolitic brown iron ores (in the Lisakovsk, Ayat, Priaral, and other fields), containing up to 35–40% Fe and 1% P. Thermomagnetic enrichment is the most promising means of removing phosphorus from brown iron ores. In this technology, the ore or concentrate is first treated with a liquid hydrocarbon reducing agent. The next steps are magnetizing roasting, magnetic enrichment of the cake produced, and subsequent dephosphorization of the magnetic concentrate by acidic leaching. In trials, the technology is tested on representative samples of Lisakovsk concentrate and Ayat and Kok-Bulak ore.