Study on extracting aluminum hydroxide from reduction slag of magnesium smelting by vacuumrnaluminothermic reduction

摘要

The reduction slag from magnesium smelting by vacuumrnaluminothermic reduction using dolomite and magnesite as rawrnmaterials consists mainly of Al_2O_3 and CaO. The alumina is morernthan 67% of the slag and is mainly in the form of CaO • 2Al_2O_3.rnThe process of producing aluminum hydroxide from the slag byrnleaching with a mixture of sodium hydroxide and sodiumrncarbonate was studied. This showed that the leaching rate ofrnalumina is more than 86% when leaching temperature is 95 , andrnL/S is 5, and leaching time is 2h. The magnesia-alumina spinelrnwhich generated in the reduction process and 3CaO•Al_2O_3•6H2Ornwhich is generated in the leaching process, are the two mainrncauses of loss of alumina. The chemical composition of aluminumrnhydroxide products obtained after carbonation precipitation canrnmeet the quality standard of the alumina plant.