关键词: 褐铁型红土镍矿, 碱预处理, 加压浸出, 镍, 钴

Abstract: The pressure leaching of low grade alkali-pretreated limonitic laterite ore by a mixed acid was investigated. After alkali-pretreatment, iron exists in the form of amorphous iron oxide while nickel is adsorbed on the surface of iron oxides in the form of nickel oxide. The preferable pressure-leaching conditions of alkali-pretreated limonitic laterite ore are determined as follows: leaching temperature of 458 K, initial acidity of leaching system with cI=2.44 mol/L, leaching time of 60 min, ratio of liquid to solid of 2:1 mL/g, and agitation speed of 500 r/min. This pressure-leaching technique is proved to be effective and stable. Under the above conditions, the extraction rates of nickel and cobalt are kept about 95% and 80% respectively while that of iron is as lower as 1%. The content of nickel and cobalt in the leaching residues is as low as 0.028% and 0.007% respectively. The valuables of nickel and cobalt can be efficiently separated from the impurity of iron. After the pressure leaching of alkali-pretreated laterite ore, iron is finally hydrolyzed and precipitated in the form of hematite which can be further reclaimed. The iron minerals in the leaching residues rarely contain nickel.

Key words: limonitic laterite ore, alkali-pretreatment, pressure leaching, nickel, cobalt