Thermodynamic and Kinetic Study of Leaching Magnesia from Natural Magnesites by Carbon Dioxide
The applicability of carbon dioxide pressure leaching for the extraction of high purity magnesia from natural magnesites has been investigated. Factors which have influence on the magnesia recovery such as time, temperature, pressure, particle size and calcination temperature have been studied. Optimum values were determined: calcination temperature was in the range 650 – 750 0C, time of the calcination was approximately 5 – 3 hours; carbon dioxide partial pressure leaching for the extraction of magnesia was about 3 bar; particle size was between 0,2 – 0,6 mm. A kinetic study of carbonation of MgO has been investigated at leaching temperature from 00C to 50 0C. Two processes were observed: the formation of a magnesium bicarbonate solution and the precipitation of magnesium carbonate. Our research has determined that the concentration of impurities in magnesium carbonate is virtually no different from their concentration in natural magnesites. Apparently, the formation of magnesium carbonate proceeds without destruction of structure. So the extraction of high purity magnesia from natural magnesites by carbon dioxide is only possible using magnesium bicarbonate. It is necessary to optimize the translation process of magnesium in solution and the technology of extraction of pure MgO from it to generate high purity magnesium on an industrial scale.
B.S. Bokstein, A.O. Rodin and B.B. Straumal
S. Klochkovskii et al., "Thermodynamic and Kinetic Study of Leaching Magnesia from Natural Magnesites by Carbon Dioxide", Defect and Diffusion Forum, Vols. 309-310, pp. 261-264, 2011