Selective separation of magnesium from olivine minerals

Abstract The aim of this investigation was the selective separation of Mg(II) from olivine, (Mg,Fe)SiO4. The feasibility of leaching of Mg2+, Fe2+, and Fe3+ from olivine and serpentinized olivine with HCl or H2SO4 solutions of pH ∼ 2 or 3.5 has been examined. The results obtained showed that, under identical conditions, HCl solution is more effective than H2SO4 in leaching of Mg2+ as well as Fe2+, and that the optimum pH is <3.5. Magnesium ions are selectively and quite effectively separated from the leaching solution by precipitation of Mg(OH)2 at pH ∼ 11.5 since most, if not all, other metal ions that exist in natural samples are pre-precipitated as hydroxides and separated by filteration. Alternatively, Mg2+ is selectively separated from the leaching solution by flotation as magnesium oleate in the 7.0–8.5 pH range.