HYDROMETALLURGICAL PROCESS FOR NICKEL OXIDE ORE

摘要

A method for the wet-smelting of nickel oxide ore by high pressure acid leach, wherein a high iron oxidation ratio is achieved in order to fix most of iron in a leach residue in the form of hematite, the amount of sulfuric acid used during leaching is minimized, and nickel and cobalt are leached out at a high leach rate. The flow rate and the carbon grade of ore slurry prepared in a first step are measured, and the amount of carbon charged in a second step is determined. The blow ratio of high-pressure air and high-pressure oxygen is subsequently adjusted so that the oxygen purity thereof is 21-60 pcnt in a second step for adding sulfuric acid and performing a leaching process by using high-pressure air and high-pressure water vapor, the oxygen blow rate is set to 200-600 Nm3 per ton of weight of carbon contained in the ore slurry and charged to the second step while the oxygen purity is maintained, and the ORP (in terms of Ag/AgCl) during leaching is kept at 400-650 mV.