用冶金级氢氧化铝制备高纯氢氧化铝及氧化铝

Preparation of High Purity Aluminum Hydroxide and Alumina Using Metallurgical Grade Aluminum Hydroxide

研究了从冶金级氢氧化铝重溶后的铝酸钠溶液中脱除杂质硅和铁并制备高纯氢氧化铝和氧化铝,考察了脱杂剂CaO及Ca-Al水滑石用量、反应温度、反应时间及Na2O浓度对脱杂的影响。结果表明:在CaO和水滑石用量均为10 g/L、85~90℃条件下反应2 h,脱杂效果较好,SiO2、Fe2O3质量浓度都可降至2 mg/L以下,种分得到的Al(OH)3中SiO2、Fe2O3质量分数低于0.003%。将种分得到的氢氧化铝通过水热法处理可深度脱钠,三水铝石转变为一水铝石,晶间及包裹Na2O返溶于水,Na2O质量分数可降至0.02%左右。水热产物于1150℃下煅烧,灼碱质量分数显著降低,Al2O3产品纯度在99.9%以上。

The removal of impurity silicon and iron in sodium aluminate solution dissolving metallurgical grade aluminum hydroxide and preparation of high purity Al(OH)3 and Al2O3 were studied.The effects of CaO and Ca-Al hydrotalcite amount,reaction temperature,reaction time and Na2O concentration on removal of impurity were examined.The results show that under the concentration of CaO and hydrotalcite of 10 g/L,temperature of 85~90℃and reaction time of 2 h,the concentration of SiO2 and Fe2O3 in the solution can be reduced to 2 mg/L.The mass fraction of SiO2 and Fe2O3 in Al(OH)3 product is less than 0.003%.The aluminum hydroxide obtained by seeding can be deeply de-sodium by hydrothermal method,the gibbsite is converted into gibbsite,and the intergranular and encapsulated Na2O is dissolved in water,and the Na2O content in the Al(OH)3 product can be reduced to 0.02%.After the hydrothermal product being calcined at 1150℃,the caustic alkali content is significantly reduced,and the purity of the Al2O3 product is over 99.9%.