Removal of iron from acidic leach liquor of lateritic nickel ore by goethite precipitate

The separation of high levels of iron from acid leaching liquor is a difficult task, especially in the atmosphere acid leaching process for laterite ore. In this paper the removal of iron by goethite precipitation from the leach liquor of reduced laterites is reported. The goethite precipitation process uses air as oxidation agent, that is, V.M. method, and does not need the pre-reduction of ferric iron since the soluble iron in leach liquor is mainly ferrous ion. The effects of pH value on the rate of iron removal and the loss of nickel to the residue were investigated. It was found the pH value had remarkable influence on the nickel loss during goethite precipitation. By carefully controlling the pH value to less than 2.5 the loss of nickel could be restricted to below 5%. Attempts of recover the nickel lost to the goethite residue through weak acid washing were unsuccessful, suggesting the retention of nickel by the goethite.