PRODUCTION OF MAGNESIUM CARBONATE

摘要

A process for producing magnesium carbonate by carbonating a magnesium silicate ore containing iron is disclosed. It is characterised by the step of contacting a slurry of the ore in water with a gaseous mixture comprising carbon dioxide and oxygen. The process is suitably carried out at elevated temperature and pressure wherein the gaseous mixture is in supercritical fluid form. It is particularly suitable for the processing of olivine and serpentine ores wherein iron is present in the +2 oxidation state. The process also optionally comprises the separation of silica and/or discrete iron oxide or hydroxide phases(s) co-produced with the magnesium carbonate, Also disclosed are downstream processes for converting the magnesium carbonate into magnesium oxide and compositions derived therefrom having cementitious properties. Cement products and concrete building materials produced from these compositions have useful structural properties and have a low carbon footprint relative to traditional Portland cement.