(1. 中南大学 冶金与环境学院，长沙 410083；
2. 贵阳铝镁设计研究院，贵阳 550004)
摘 要: 通过分析含硅铝酸钠溶液脱硅过程二氧化硅浓度、脱硅渣成分和物相，研究氧化镁在铝酸钠溶液中的反应行为。结果表明，在95~100 ℃的常压脱硅条件下，氧化镁在铝酸钠溶液中易形成水合碳铝酸镁，对溶液基本无脱硅效果，氧化铝损失较多，但氧化镁能显著促进石灰的脱硅作用，且在石灰用量一定时随氧化镁添加量的增加，溶液的脱硅率显著升高；在190 ℃的高压脱硅条件下，氧化镁对铝酸钠溶液石灰脱硅作用的促进不明显，但它可使脱硅渣的钠硅比(质量比)显著降低；无论是单独采用石灰(CaO)，还是采用石灰和氧化镁混和物脱硅，含硅铝酸钠溶液高温脱硅渣中均含有钠硅渣相，这与热力学分析结果一致。
关键字: 氧化镁；铝酸钠；石灰；脱硅；钠硅渣
（1. School of Metallurgy and Environment, Central South University, Changsha 410083, China;
2. Guiyang Aluminum and Magnesium Design and Research Institute, Guiyang 550004, China）
Abstract:The reaction behavior of MgO in the desilication process of sodium aluminate solution was studied by analyzing SiO2 concentration variation in solution and compositions and phases of the desilication slag. The results indicate that under desilication conditions of 95-100 ℃ and normal pressure, MgO can react with SiO2-containing sodium aluminate solution to form the magnesium hydroaluminocarbonate and cause the loss of alumina. MgO has almost no desilication effect in the normal pressure desilication process, but it can promote the desilication rate of CaO significantly and the desilication rate increases with the increase of MgO amount when the dosage of CaO is constant. Under desilication conditions of 190 ℃ and high pressure, MgO has little effect on the desilication rate of CaO, but it can decrease the mass ratio of soda to silica of desilication slag. The sodium aluminosilicate hydrate is one of the main phases of the slags produced from high temperature desilication process with either MgO or mixture of MgO and CaO as desilication agent, which agrees with the result of thermodynamic calculation.
Key words: magnesium oxide; sodium aluminate; lime; desilication; sodium aluminosilicate hydrate
