The novel process producing magnesium metal using vacuum aluminothermic reduction

which utilizes dolomite and magnesite as raw materials and aluminum powder as reductant

produces reducing slag containing-rich CaO·2Al2O3.The reducing residue can be solved by a mixture solution of sodium hydroxide and sodium carbonate

and a solution of sodium aluminate is produced which can be decomposed by CO2 to obtain aluminum hydroxide.For the production process of aluminum hydroxide

effects of process parameters on leaching rate of alumina are investigated systematically and the performance of aluminum hydroxide obtained was detected.The results show that the alumina leaching rate from the residue is above 85% under the conditions of NaOH concentration 80 g·L-1

Na2CO3 concentration 110 g·L-1

leaching temperature 95℃

leaching time 120min and L/S 6.Whiteness of aluminum hydroxide obtained carbonation precipitation at 50℃ is over 98

and average particle size is 26.98μm.