SELECTIVE REDUCTION - MIXED CHLORIDE LEACH PROCESS FOR LATERITES

摘要

Laterite ores can be classified as low iron, medium iron, and high iron. The low iron (<15 % Fe) ores, which are mostly saprolytic in nature, contain 1.7- 2.3% Ni and are treated by pyrometallurgical smelting processes to produce ferronickel or matte. More recently, the medium iron deposits (15-30 % Fe) are treated by mini blast furnaces in China to produce low grade ferronickel, nickeliferous iron or matte. High pressure leach using sulphuric acid has been considered the best option for high iron (>35 % Fe) limonitic ores. However, with increasing world demand for sulphur due to requirements in the fertilizer industry in growing economies, these processes are becoming uneconomical. A selective reduction -mixed chloride leach process presented here provides an alternative option. Novel reduction and leaching process steps are described to make this alternative more economically attractive in the current market conditions.