Optimal conditions for selective reduction process of nickel laterite ore

A low-grade nickel laterite ore from Indonesia was selected to investigate the effect of temperature and time of reduction upon the extraction of nickel through the selective reduction-magnetic separation process to produce the ferronickel. The nickel ore was mixed with5 wt.% of anthracite coal and 10 wt.% of sodium sulfate additive. The mixed ore was pelletized into 10-15 mm of diameter. A series of selective reduction processes were carried out into the pellet ores at various temperatures of 950-1150 C for 60-120 minutes. The optimal selective reduction parameters of nickel laterite ore were observed clearly. The experimental results indicated that the reduction reactions proceed more completely at a higher temperature and longer reduction time. The optimum of nickel grade and recovery in the ferronickel concentrate was obtained at the reduction temperature of 1150 C for 120 minutes, which was 8.45% and 72.1%, respectively. The increasing of temperatures and times of reduction process resulted in higher of troilite phase formation which suppressed the iron metallization and also increased the ferronickel particle size.