菱镁矿混合氯化镁焙烧制备高纯氧化镁

采用菱镁矿添加无水氯化镁混合焙烧的方式，在较低焙烧温度下制备了高纯度的氧化镁。通过热重-差热（TG-DTA）法分析了菱镁矿的焙烧反应过程，并对焙烧产品进行了X射线衍射（XRD）、扫描电镜（SEM）及纯度分析。与传统焙烧方法制备氧化镁相比，添加氯化镁的焙烧工艺可有效地达到除钙效果。通过机理探讨表明，氯化镁渗透到菱镁矿中起隔断作用，有效增加了菱镁矿的比表面积，降低了焙烧温度，达到了节能降耗的效果。在焙烧温度为650 ℃、保温时间为1 h条件下，所得氧化镁的纯度可达99.3%，钙杂质质量分数可降至0.07%。

Preparation of high purity magnesia from calcining magnesite mixed magnesium chloride

High-purity magnesium oxide was prepared by calcining magnesite which mixed with anhydrous magnesium chlo-ride at a lower calcination temperature.The thermal decomposition of mixed powders was analyzed by thermogravimetric anal-ysis and dynamic thermogravimetric analysis（TG-DTA）.The prepared product was also characterized by X-ray diffraction（XRD），scanning electronic microscope（SEM），and purity analysis.Compared with the traditional method，the results showed that adding magnesium chloride can effectively remove calcium.Through mechanism discussion，because of chloride ion′s penetration，magnesium chloride played a role of partition to magnesite，it made magnesite′s specific surface area increase and calcination temperature decrease，which got the effect of energy-saving and cost-reducing.The product′s purity could reach 99.3% and calcium impurity mass fraction reduced to 0.07%，when calcination temperature was 650 ℃ and calcination time was 1 h.