Effect of Calcium/Aluminium ratio on MgO containing calcium aluminate slags

摘要

MgO is the main impurity in calcium aluminate slags. Thernpresence of MgO will change the nature of the alumina bearingrnphases and decrease the alumina leaching properties of the slag. Inrnorder to remove or reduce the negative effect of MgO, the methodrnof changing the C/A (CaO/Al_2O_3, molar ratio, excluding CaO inrn2CaO·SiO_2) of the calcium aluminate slag was studied and therneffect on leaching mechanism was also analyzed. The resultsrnshowed that the formation of the quaternary compoundrn20CaO·13Al_2O_3·3MgO·3SiO_2 (C_(20)A_(13)M_3S_3) is inhibited withrnincreasing C/A in the calcium aluminate slag, and the MgOrncrystallized in the form of periclase under these conditions. Therernis an optimal C/A to improve the alumina leachability of therncalcium aluminate slag. The increase of C/A could not remove thernnegative effect of MgO on leachability completely, and thernoptimal C/A of the slag increases with increasing MgO content.