Studies on the Nickel Extraction (2nd Report)

Pressure Leaching of the Garnierite Ore

Abstract

The extraction of nickel from the New Caledonian garnierite are with sulfuric acid solution was studied:
1) 10g of the are was pre-treated with sodium hydroxide solution of the concentration of 33-150g/l at about 200°C in a autoclave before leaching with sulfuric acid solution. The pre-treated are was leached with 200 ml of 5% sulfuric acid first and then leached again with 10% of sulfuric acid for an hour. The nickel which was leached out with the above mentioned treatment was 89% of the total nickel in the ore, but it was about 79% in the case of one which was not pre-treated with sodium hydroxide solution.
2) The pressure leaching of nickel with sulfuric acid was applied to the are which was not pre-treated. 20g of this was laachd with 300ml of sulfuric acid solution under the compressed air at different temperatures. 90% of the nickel in the are was leached out under the following condition; the concentration of sulfuric acid was 10%, the temperature 180°C, total pressure being 10kg/cm², the time 2 hours, and the agitation speed 200 r.p.m.