Use of equimolar cysteine/ascorbic acids to recover MCP synthesized Ti(Mg) alloy

Abstract

Dissolution of waste by-products of mechanochemical processing (MCP) synthesis of Ti(Mg) alloy, from TiO2 and 15 wt.% excess Mg, was conducted in equimolar cysteine/ascorbic acids. The synthesized alloy is inherently mixed with MgO and other oxides of Ti and the objective was to leach out the by-products of the MCP process and hence recover a pure isolated Ti-Mg powder. The dissolution of particulate polycrystalline MgO and TiO2, and Ti-20Mg solid solution (obtained from milling blended elemental powders) was also investigated to note how they individually behaved in the leach reagent. The study indicated that separation was possible although with considerable contamination from MgO and TiO2 and inadvertent co-dissolution of Ti(Mg) alloy. Further work on sequential dissolution of the by-products using equimolar cysteine/ascorbic acids and inorganic acids is recommended. Equimolar cysteine/ascorbic acid leach reagent was effective in dissolving TiO2; while inorganic acids will dissolve MgO. It is envisaged that sequential dissolution will minimise the unintended co-dissolution of the Ti(Mg) alloy.