| 摘要 |
<p>A process for preparing substantially pure magnesium oxide from crude magnesium-containing compounds which have an iron impurity sufficiently low to be removable by selection of the process conditions, characterised in that the process comprises calcining the crude magnesium-containing compounds to crude magnesium oxide, forming a slurry of the crude magnesium oxide and treating the slurry with carbon dioxide to convert at least part of the magnesium content of the slurry into magnesium bicarbonate, said treatment being carried out at a temperature of from 25-50oC, and at a pulp density selected to permit maximum magnesium extraction with minimum iron extraction, removing the unreacted solid from the magnesium bicarbonate solution so produced, air sparging and/or heating the solution after clarification to produce a precipitate of hydrated magnesium carbonate and/or basic magnesium carbonate, separating the precipitate and decomposing it to produce substantially pure magnesium oxide. </p> |
