Separation of nickel and iron from lateritic ore using a digestion - roasting - leaching - precipitation process

This paper investigates extraction of nickel and iron from a lateritic nickel ore from the Caldag region of Manisa in Turkey. The ore sample contains 1.2% Ni, 24.77% Fe and 0.062% Co. The process applied includes digestion with 40 wt-% sulfuric acid at 200 °C for 60 min, roasting at 700 °C for 15 min, leaching with water for 30 min at 1:5 solid/liquid ratio (by weight) and precipitation of the remaining iron at pH 3 and 60 °C. In order to improve nickel and cobalt extractions using the digestion-roasting- leaching-precipitation process (DRLP), Na₂SO₄ addition in the roasting stage was examined. Under the optimum conditions and in the presence of Na₂SO₄, 86.2% Ni and 94.2% Co extractions were obtained with almost zero iron content. As a result, 2.07 g dm_-3 Ni, 0.12 g dm_-3b c Co and 0.05 g dm_-3 Fe could be achieved in the pregnant leach solution within nearly 2.5 hours.