真空铝热炼锂还原渣回收氢氧化铝的研究

Recycle Aluminum Hydroxide from Residue of Vacuum Aluminothermic Reduction Lithium Process

碳酸锂、氧化铝和氧化钙混合常压煅烧可获得LiAlO_2熟料,经真空铝热还原可得金属锂,同时得到铝酸钙系还原渣,主要成分为CaO·Al_2O_3和12CaO·7Al_2O_3.为综合利用该还原渣,通过混合碱液溶出、碳酸化分解回收氢氧化铝.研究溶出温度、溶出时间、还原渣粒度、碳酸钠质量浓度、氢氧化钠质量浓度、金属锂还原率对氧化铝溶出率的影响.结果表明:以锂还原率97%的炼锂还原渣为原料,粒度分布d_(90)74μm、溶出温度95℃、溶出时间120 min、碳酸钠质量浓度240g/L及氢氧化钠质量浓度8.9g/L的条件下,氧化铝的溶出率为80. 73%.溶出的铝酸钠溶液经碳分可获得体积平均粒径6.50μm及白度值96.9的氢氧化铝.

When lithium was produced in the process of aluminothermic reduction LiAlO2 clinker in vacuum condition w here the clinker was prepared by calcined mixture of lithium carbonate,alumina and calcium oxide at normal atmosphere,the reduction residue containing CaO·Al2O3 and12 CaO·7 Al2O3 was obtained. In order to recycle the reduction residue,the residue was firstly leached with a mixture solution of sodium hydroxide and sodium carbonate,and then aluminum hydroxide was produced by decomposing the leaching solution with carbon dioxide. The effects of leaching temperature, leaching time, particle size, sodium carbonate concentration, sodium hydroxide concentration and lithium reduction rate on leaching rate of alumina were investigated.The results showed that the leaching rate of alumina is 80. 73% under the conditions of the particle size distribution d90 of 74 μm,the leaching temperature of 95 ℃,the leaching time of 120 min,the Na2 CO3 concentration of 240 g/L and NaOH concentration of 8. 9 g/L,w hen the residue is from the reduction lithium process with a reduction rate of 97%. The average particle size and the w hiteness of aluminum hydroxide obtained by carbonation precipitation are 6. 50 μm and 96. 9,respectively.