真空热还原法是原镁生产的主要方法,中国是世界上最大的原镁生产国.通过对皮江法、铝热还原氧化镁、碳热还原氧化镁三种制备金属镁方法的热还原反应的热力学计算,综合考虑一次性资源和能源消耗量、温室气体排放量和固体废物排放量、工艺过程的环境相容性等因素,得出结论为:真空铝热还原法制备金属镁的工艺具有一次性资源消耗量低、固体废物排放量和温室气体排放量小的优点.结合白云岩钙镁分离过程,可以实现利用白云岩资源制取金属镁过程的清洁化生产.%China is the largest producer of magnesium in the world.The vacuum-thermal reduction method is the main one for the preparation of magnesium.In this paper,the Gibbs free energy changes for the reaction in the Pidgeon process,aluminothermic reduction of magnesia and carbothermic reduction of magnesia were calculated over at different temperatures and pressures.The consumption of resources and energies,the discharges of the greenhouse gas and solid wastes,the environmental compatibility of the three thermal reduction processes were studied.It was revealed that aluminothermic reduction of magnesia offers advantages of the lower resource and energy consumption as well as lower discharges of greenhouse gas and solid waste.A potential technique for the clean utilization of the dolomite is the separation of the magnesia component and calcia component to obtain magnesia and calcium carbonate,followed by the thermal reduction of magnesia to obtain magnesium.
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