STUDY ON SELECTIVE REDUCTION AND MAGNETIC SEPARATION OF LOW-GRADE NICKEL LATERITE ORE TO PRODUCE HIGH NICKEL CONCENTRATE

摘要

There is a strong demand for nickel metal due to quick development of stainless steel and new electrical materials industries, most of which are extracted from sulfide ores, resulting in a serious depletion of sulfide resources. Therefore, more attentions have been paying to extracting nickel from nickel laterite ores these years, accounting for some 60 per cent of total nickel metal production. An effective process of selective reduction roasting-wet magnetic separation was studied to manufacture high nickel concentrate from tropical low grade nickel laterite ore obtained from Indonesia in this paper. Research of the effect of process parameters on reduction was carried out of low-grade nickel laterite ore (lower than one per cent Ni) at 1250°C by using coal as the reductant. The reduced ore was then upgraded by magnetic separation, 75 per cent of the total mass being rejected as tailings, and a high grade nickel concentrate, assaying 5.1 per cent Ni and 82.66 per cent Fe_(total), was produced at a nickel recovery of 98.79 per cent. This concentrate is a good quality burden for EAF. There are great difficulties in the enrichment of nickel from low grade laterite ore by pyrometallurgical processes due to the similar reducibility of the nickel and iron oxides in the ores. Therefore, some additives were developed to suppress the reduction of iron minerals and improve the reduction of nickel and the growth of newly formed element nickel, upgrading of nickel by wet magnetic separation being achieved for manufacturing high nickel grade concentrate.