硼镁石真空铝热炼镁还原渣提取高白氢氧化铝

Extract of High-Whiteness Aluminum Hydroxide from Residues of Magnesium Production by Aluminothermic Reduction Szaibelyite

以煅烧硼镁石为原料真空铝热还原炼镁得到的还原渣中富含12CaO·7Al2O3,该还原渣可通过氢氧化钠和碳酸钠的混合碱液溶出得到铝酸钠溶液和富硼料,铝酸钠溶液通过碳酸化分解可制备氢氧化铝.以硼镁石铝热炼镁所得还原渣为原料,研究了溶出温度、时间、碳酸钠及氢氧化钠质量浓度对氧化铝溶出率的影响,并对碳分产物进行性能研究.结果表明,在氢氧化钠质量浓度12 g/L,碳碱质量浓度210 g/L,溶出时间120 min,溶出温度95℃,液固比为6的条件下,炼镁还原渣中氧化铝的溶出率为85.21%.氢氧化铝产品为α-Al(OH)3,白度大于98,SEM显示其晶粒小于1μm.

The vacuum aluminothermic reduction process can produce magnesium metal and the reducing residue contains rich 12CaO .7Al2O3. The reducing residue can be solved by a mixture solution of sodium hydroxide and sodium carbonate. The filter residue is rich boron stuff and the filtrate is a solution of sodium aluminate which can be decomposed by CO2 to obtain aluminum hydroxide. In present work the effects of leaching temperature, time, NaOH concentration and Na2CO3 concentration on the leaching rate of alumina were investigated systematically and the performances of aluminum hydroxide obtained were detected with the reduction residue as raw materials. The results showed that the alumina leaching rate from the residue was above 85.21% at the conditions of NaOH concentration 12 g/L, Na2CO3 concentration 210 g/L, leaching temperature 95 ℃, leaching time 120 min and liquid-solid ratio 6. The whiteness of the aluminum hydroxide obtained was over 98. The chemical formulation of the product is α-Al （OH）3. The SEM results showed that the grain size was less than 1 μm.