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对以煅后白云石和煅后菱镁石为原料,以铝粉为还原剂的新法炼镁技术的热力学进行了分析,并进行了真空热还原实验。通过X射线衍射和扫描电子显微镜对还原渣的主要物相与物质形态进行了分析。实验结果表明:以煅后白云石和煅后菱镁石为原料,以铝粉为还原剂的新法真空热还原炼镁技术是可行的,在还原温度1200℃,还原时间2 h,铝粉过量5%和无氟盐添加剂的条件下,氧化镁的还原率可达90%,CaF2或MgF2的添加可大幅度地提高还原过程中氧化镁的还原率,降低还原温度。还原后还原渣主要物相为CaO.2Al2O3,还原渣中氧化铝的含量在65%以上,氧化硅含量低于2%,是一种非常适合生产氢氧化铝的原料。
The thermodynamics of the new method of magnesium refining using calcined dolomite and calcined magnesia as raw materials and aluminum powder as reductant was analyzed and the vacuum thermal reduction experiment was carried out. The main phase and material morphology of the reduced slag were analyzed by X-ray diffraction and scanning electron microscopy. The experimental results show that vacuum calcination of magnesium with calcined dolomite and calcined magnesia as raw material and aluminum powder as reductant is feasible. Under reducing temperature of 1200 ℃, reduction time of 2 h, excess aluminum powder 5 % And non-fluoride salt additives, the reduction rate of magnesium oxide can reach 90%. The addition of CaF2 or MgF2 can greatly improve the reduction rate of magnesium oxide and reduce the reduction temperature during the reduction. After reduction, the main phase of the reduction slag is CaO.2Al2O3. The content of alumina in the reduction slag is above 65% and the content of silicon oxide is below 2%, which is a very suitable raw material for the production of aluminum hydroxide.