Study on Process of Microwave Magnetizing Roast for Low-Grade Hematite

The microwave magnetic roasting process of low-grade hematite under low temperature was studied experimentally. The effects of roasting temperature, carbon content and roasting time on the reduction and magnetic separation were investigated. It shows that the best percent reduction is 10.96％(near to theoretical value 11.11%)which can be obtained under the condition of roasting temperature of 650°С , carbon content of 1.0% and roasting time of 10 minute. The results of magnetic separation show that the best magnetic separation grade for the sintered ore occurs at 570 instead of 650°С owing to the sintering of ore powders at high temperature of 650°С . Further ball-milling and magnetic separation of this concentrate produces two kind of final concentrate, one of which is in grade 65.6% with the recovery being 45.3%, and the other is in grade 63.4% with the recovery being 62.6％. After the magnetic separation, concentrate ore meets the iron-smelting requirements because of its low S and P content and high grade. This magnetic process results in the enrichment of RE and Nb in tailing ore, which can be reused for the extraction of Rare Earth and Nb.