Thermodynamic and technico-economic analyses of the HCl-leach of magnesite and serpentine

CIM Bulletin, Vol. 92, No. 1034, 1999

M. Nagamori, Thermochemistry Consultant, Ste-Foy, Quebec A.J. Plumpton, Lakefield Research Limited, Lakefield, Ontario

Commercial HCl-leaching of magnesite and serpentine yields highly concentrated aqueous solutions containing 25 mass % to 33 mass % MgCl2. The partial molar enthalpies and heat capacities, the ionic activities of Mg2+ and ClÐ, and the Raoultian activity of H2O have been assessed for the concentrated MgCl2-H2O solutions at temperatures of 348 to 373 K. These thermodynamic data are used to calculate the pH of aqueous MgCl2 solutions saturated with a Mg-bearing mineral such as magnesite, serpentine, brucite, forsterite, enstatite or talc. On the basis of these thermodynamic data, technico-economic aspects are discussed as to neutralization with pulverized MgCO3, water evaporation from the MgCl2 solutions, and ore composition including such minor constituents as CaCO3, FeCO3 and Fe3O4.
Keywords: Metallurgy, HCl leaching, Magnesite, Serpentine, Thermodynamic analysis, Technico-economic analysis.