High purity MgO is widely used in various fields as an important magnesium compound. The separation of Mg and Ca is of great importance for the preparation of high purity MgO from dolomite. In this study, the key effects of carbonization temperature and nano-calcium carbonate agglomeration on the separation mechanism of calcium and magnesium have been investigated. The results indicated that the reaction in the carbonization process was stepwise. Precise control of the carbonization temperature was essential for the formation of Mg(HCO 3 ) 2 due to its low reaction efficiency at lower temperatures or decomposition markedly at higher temperatures. Meanwhile, there was a common-ion effect in solutions containing Mg 2+ and Ca 2+ . Nano-CaCO 3 particles were formed during carbonization and agglomerated with the prolongation of static time. A product with a purity of 99.56% MgO and 0.16% CaO was obtained under the optimized conditions: ratio of liquid–solid 30 L/g, carbonization temperature 22–25 °C, carbonization time 1 h, and refining time 4 h. This work has important guiding significance for the preparation of high purity magnesium oxide from dolomite.

中文翻译：

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白云石中高纯氧化镁的制备及镁、钙的精密分离机理

高纯MgO作为重要的镁化合物被广泛应用于各个领域。Mg和Ca的分离对于从白云石中制备高纯度MgO具有重要意义。本研究考察了碳化温度和纳米碳酸钙团聚对钙镁分离机理的关键影响。结果表明，碳化过程中的反应是逐步进行的。精确控制碳化温度对于 Mg(HCO 3 ) 2 的形成至关重要，因为其在较低温度下的反应效率低或在较高温度下分解显着。同时，在含有Mg 2+ 和Ca 2+ 的溶液中存在共离子效应。纳米CaCO 3 颗粒在碳化过程中形成并随着静止时间的延长而团聚。在优化条件下获得纯度为99.56% MgO和0.16% CaO的产品：液固比30 L/g，碳化温度22-25°C，碳化时间1 h，精炼时间4 h。该工作对白云石制备高纯氧化镁具有重要的指导意义。