Production of pure MgCl2 solution suitable for the production of magnesium metal from an impure magnesite ore or concentrate

摘要

A process for producing a substantially pure, concentrated MgCl2 solution suitable for subsequent molten salt electrolysis to magnesium metal from an impure magnesite ore or concentrate is disclosed. The process comprises the steps of calcining a magnesite ore or concentrate at a temperature greater than 600 DEG C. to decompose most of the magnesite and form a reactive magnesia, dissolving such reactive magnesia with either concentrated hydrochloric acid or hydrogen chloride gas with the addition of a surface active wetting agent to produce an impure concentrated MgCl2 solution, and reacting such impure concentrated MgCl2 solution with a minimum of excess magnesia to increase the pH of the solution to at least 5.5 to precipitate undesirable impurities from solution and produce a substantially pure MgCl2 solution.