Influence of MgO on Calcium Aluminate Slag System with Lower Calcium

The effect of MgO on phase composition, alumina leaching properties and the self-disintegrating rate of calcium aluminate slag were investigated by X-ray diffraction and another analysis method. And a feasible method is proposed to eliminate the negative effects of MgO. The results shows that: the phase of 2CaO·SiO2(C2S)、20CaO·13Al2O3·3MgO·3SiO2(Q phase) and 12CaO·7Al2O3(C12A7) are formed when there is MgO in slag with the C/A=1.4 and A/S=1.3. The content of Q phase increase and the leaching rate of slag reduce with increasing the temperature and the content of MgO. MgO would reduce self-disintegrating rate of slag. CaSO4·2H2O can improve the self-disintegrating the leaching properties of slag by promoting the synthesis of C12A7 and inhibit the synthesis of Q phase.