The investigations on solvent extraction of Ni-Co from the ammoniacal leach liqours from the Pomalaa low grade nickel laterite have been carried out.
Extraction rate of metallic ion with Versatic Acid 10 in pH neutral range is Cu>Ni>Fe>Co (II)>Mg. Amount of ammonium ion of 13-15% is co-extracted with Versatic Acid 10 in nickel extraction section. However, ammnonium ion of 98% co-extracted with Versatic Acid 10 is stripped by two stage water scrubbing.
In high concentration of ammonium solution, cobalt ion is stably involved as Co (III) and it is not extracted with Versatic Acid 10.
However, Co (II) can be extracted with Versatic Acid 10 after reduction of Co (III) by metallic cobalt. Remained ammonium concentration of 0.8-1.0 mol/l in nickel raffinate is necessitated due to reduced from Co (III) to Co (II) and in that case, two stage reductions by metallic cobalt and two stage extraction with Versatic Acid 10 are effective for extraction of Co (III).
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