Nickel extraction from laterite ores - using a two phase treatment with acid and basic magnesium carbonate

摘要

Extraction of nickel from laterite ores by acid leaching is improved by neutralising the products of backing in two stages, the first at up to pH 1.6-1.7 being effected in the leaching tank by injection of an aq. paste of treated serpentine, the second at pH 2.4-2.5 after sedimentation of this paste by adding an aq. paste of basic magnesium carbonate obtd. from the treatment of the serpentine to increase the nickel content and reduce the magnesium content. >94% of the Ni and 85% of the cobalt present in the serpentine can be extracted. The range of pH at which subsequent treatment of the remaining liquor can be effected is increased given that 80-90% of Al and Fe present are precipitated in the liquid part of the paste during the first neutralisation step. The final pH can be controlled by using a solid neutralising agent since the major part of the Fe and the Al have been first removed.