Establishment Of Compounding Optimum Mathematical Model For The Pure System Of Calcium Aluminate Slag

The exploitation and utilization process of the trihydrate alumina type bauxite with high iron and high silica in Guigang, Guangxi province, which is called "minerals sintering-blast furnace smelting-alumina leaching" proved technically and economically feasible. Industrial test of "minerals sintering-blast furnace smelting" achieved success. In the whole process, the iron yield was up to 98%, the disintegrating rate of the calcium aluminate slag exceeded 97% and the leaching rate of alumina reached 81.64%.The property of the calcium aluminate slag which is obtained by blast furnace smelting will affect the recovery of alumina directly. The main component of the calcium aluminate slag are 12CaO·7Al2O3 andγ-2CaO·SiO2. Because of the complexity of slag and the low yield of alumina, the blending optimization in furnace smelting process was researched based on the previous results in this paper. Calculation of complex chemical equilibrium was introduced to establish the compounding optimum mathematical model for the pure system of calcium aluminate slagThe compounding optimum mathematical models of CaO-SiO2 binary system and CaO-Al2O3-SiO2 ternary system were established based on Gibbs free energy minimization method. The effect of lime dosage on the existing states of Al2O3 and SiO2 in the slag was researched in this paper. The calculated results by the mathematical model were consistent with the practical test data ultimately: the optimal slag was attained at both C/S=2 and C/A=1.7, while the component of slag was complex in other cases.The compounding optimum mathematical model of the calcium aluminate slag composition in CaO-MgO-Al2O3-SiO2 quarternary system was established on the basis of the mass action equations method. The equilibrium compositions of the calcium aluminate slag with different contents of MgO were calculated by this mathematical model. The verified test showed that the calculated results by this mathematical model were consistent with the practical test data ultimately. MgO affected the existing state of Al2O3 in the slag. With the increase of MgO addition, the existing state of Al2O3 in the slag was transformed from 12CaO·7Al2O3 into 20CaO·13Al2O3·3MgO·3SiO2.