Removal of Impurities in Iron Ore by Na₂O-B₂O₃ Flux

Abstract

Removal of impurities in fine-grained iron ore with Na₂O-B₂O₃ flux and its mechanism have been investigated by use of the flux leaching and the recrystallization methods. The isolated impurities as well as those on the surface of ore particles were removed by the former method, while the inclusions prerent inside the particles together with the above-mentioned impurities were removed by the latter method. In the flux leaching method, the high yield of iron oxide and the low content of impurities were obtained at flux compositions of Na₂O·2B₂O₃ and 2Na₂O·5B₂O₃. The contents of Si, Al, Ca, Mg, Mn, V decreased with increasing temperature from 850°C to 1450°C ; these observations were explained by the break up of ore particles and the increase of the amount of recrystallized iron oxide. About 80% of iron oxide yield was obtained in both flux treatments by use of the Na₂O-2B₂O₃ flux.