氟盐对炼镁还原渣中氧化铝浸出率的影响研究

以白云石和菱镁石为原料以铝粉为还原剂真空热还原炼镁过程中添加氟化钙可使镁还原率提高5%以上,还原温度降低50℃,还原后还原渣的主要物相为CaO.2Al2O3,加入的氟化钙在还原过程会参与反应生成氟铝酸钙。在实验室以氢氧化钠和碳酸钠的混合碱液对该含氟盐还原渣中氧化铝的浸出进行了研究,研究结果表明:经碱液浸出后还原渣中的CaO.2Al2O3全部被分解,还原渣中的氧化铝浸出率在70%以上,浸出渣的主要物相为CaCO3。含氟盐炼镁还原中氧化铝的浸出率比不含氟盐的氧化铝浸出率低10%以上,在还原过程中生成的氟铝酸钙和浸出过程中生成的水合铝酸钙是导致氧化铝损失增加的主要原因。

Study on the effect of fluoride on the alumina leaching rate of magnesium smelting reduction slag

The reduction ratio of MgO can be raised by more than 5% and the reduction temperature can be lowed 50℃ when some CaF2 are added in vacuum-thermal reduction of magnesium production using magnesite and dolomite as materials and using aluminum powder as reductant.The main phase of the reduction slag from magnesium smelting by vacuum aluminothermic reduction is CaO·2 Al2O3,and the CaF2 is involved in reduction reaction and form calcium fluoraluminate(11CaO·CaF2·7Al2O3).The process of extracting alumina from the reduction slag with a mixture of sodium hydroxide and sodium carbonate was studied.The results show that the CaO·2Al2O3 can be decomposed completely and more than 70% of alumina in the reduction slag can be leached.The main phase of leaching slag is CaCO3.The alumina leaching rate of the reduction slag containing fluoride is lower than the reduction slag without fluoride by more than 10%.The calcium fluoraluminate generated in the reduction process and calcium aluminate hydrate(3CaOAl2O36H2O) generated in the leaching process are the main ways of increasing loss of alumina.