UPGRADING OF SUPERFINE LOW-GRADE HAEMATITE ORES BY REVERSE FLOATATION DIRECT REDUCTION LOW INTENSITY MAGNETIC SEPARATION PROCESS

摘要

With the rapid development of iron and steel industry in China, a soaring demand for iron oresrnbrings about much attention to developing superfine low grade haematite, amounting to overrnseveral ten billion tonnes. A study of reverse floatation-direct reduction-low intensity magneticrnseparation (RFDRLM) process was carried out to beneficiate the run-of-mine ore mined fromrnHunan Province. Mineralogy was measured that the run-of-mine ore is of superfine low grade orerntype, assaying 27.23 per cent Fe and with main valuable minerals of haematite occurring at size ofrnbetween 3～5 μm. And the effect of various parameters of the reverse flotation of run-of-mine orernon the recovery and grade of rough iron ore concentrate was investigated to produce rough iron orernconcentrate assaying 33.74 per cent Fe at a recovery of 78.42 per cent, which is the feed of furtherrnprocess to manufacture final iron ore concentrate. Effects of various factors on direct reductionlowrnintensity magnetic separation of the rough concentrate were tested. The result showed thatrnfinal iron ore concentrate, assaying 73.68 per cent Fe and 91.99 per cent metallization degree atrnan overall iron recovery of 63.96 per cent, is produced under the following conditions: reducingrnthe rough concentrate briquette at 1100℃ for 80 min and 2.5 coal/ore mass ratio, grinding thernreduced briquette up to 97.60 per cent passing 0.030 mm and magnetic separation at 47.76KA/mrnfield intensity. It shows that the superfine low grade haematite can be efficiently upgraded byrnthe RFDRLM process. It is significantly important to preliminarily upgrade run-of-mine ore andrnreject gangue minerals by reverse flotation for saving investment and reducing operation cost byrndecreasing the feedstock of the subsequent process of direct reduction-magnetic separation. Thernfinal concentrate as a highly metalised burden will play significant role in enhancing blast furnacernoperation to gain a higher output and lower coke rate.