Recovery of MgO from dolomite by novel dissolution method using ion exchange resin

摘要

A strongly acidic ion exchange resin with hydrogen form, H-R, is a novel dissolution agent for sparingly soluble inorganic materials in aqueous media. The dissolution proceeds by cation exchange reaction between H-R and dissolved ion of minute quantities, which promotes further dissociation tendency of the material to achieve complete dissolution. Furthermore, the dissolution method is very effective to dissolve Ca(OH)_2. In the present study, two kinds of dolomite ore, Mg,Ca(CO3)_2, from two countries, Japan and China, were used to remove Ca(OH)_2 for comparison. The separation technique is based on the difference of hydration tendency and solubility of the hydrate, i.e. remarkable difference in hydration tendency between CaO and MgO, decomposition product of dolomite, results in complete hydration of CaO to Ca(OH)_2 having higher solubility in water and higher selectivity for the H-R. But it was found that the recovered MgO disappeared with further addition of H-R. So, further investigation to measure the heat of dissolution of MgO and Mg(OH)_2 was undertaken by calorimetry.