Extraction of alumina from the magnetic separation tailings derived from reductive roasting of bauxite residue

摘要

Much work has been done to recycle iron from bauxiternresidue via reductive roasting-magnetic separation process, ofrnwhich more than 85% iron could be recycled as powderedrnmetallic iron, but insufficient efforts have been made to utilize thernmagnetic separation tailings which were rich in valuablerncomponents like aluminum, titanium etc. This study was thereforernfocused on the alumina recovery from the above-mentionedrntailings based on alkali leaching. The effects of the parametersrnlike concentration of leaching agent (NaOH), temperature andrntime to the extraction of alumina have been investigated. Besides,rnthe influence of the up-stream reductive roasting process andrnsodium additives on the extraction of alumina have also beenrnstudied. The results showed the reductive roasting process wasrnfavorable to the extraction of alumina while the sodium additivesrndemonstrated an adverse effect. 82.90% alumina was leachedrnunder the optimal conditions from a bauxite residue containingrn19.59 wt. % Al_2O_3