Two-stage reduction for the preparation of ferronickel alloy from nickel laterite ore with low Co and high MgO contents

The preparation of ferronickel alloy from the nickel laterite ore with low Co and high MgO contents was studied by using a pre-reduction-smelting method.The effects of reduction time,calcination temperature,quantity of reductant and calcium oxide (CaO),and pellet diameter on the reduction ratio of Fe and on the pellet strength were investigated.The results show that,for a roasting temperature ＞800 ℃,a roasting time ＞30 min,1.5wt％ added anthracite coal,5wt％ added CaO,and a pellet size of～10 mm,the reduction ratio of Fe exceeds 70％ and the compressive strength of the pellets exceeds 10 kg per pellet.Reduction smelting experiments were performed by varying the smelting time,temperature,quantity ofreductant and CaO,and reduction ratio of Fe in the pellets.Optimal conditions for the reduction smelting process are as follows:smelting time,30-45 min;smelting temperature,1550℃;quantity of reductant,4wt％-5wt％;and quantity of CaO,5wt％;leading to an Fe reduction ratio of 75％ in the pellets.In addition,the mineral composition of the raw ore and that during the reduction process were investigated by process mineralogy.