Formation rate of calcium ferrite melt in iron ore sintering process

Synopsis:The formation rate of primary calcium ferrite melt and the dissolution rate of solid hematite into molten Calcium ferrite in a iron ore sintering process were investigated under the conditions of various SiO2 and Al2O3 contents. The formation rate of primary calcium ferrite melt was measured by the melting examination method for the triangular pyramid shape compacts made from hematite, calcium carbonate, silica or alumina powder mixing. The dissolution rate of solid hematite into molten calcium ferrite was determined by measuring the weight loss of hematite rod dipped in molten calcium ferrite bath. The addition of SiO2 was more effective than the addition of Al2O3 for increasing the melting rate and reducing the melt formation temperature in calcium ferrite system. On the other hand, the addition of Al2O3 was more effective than the addition of SiO2 for increasing the dissolution rate of solid hematite into the generated molten ternary calcium ferrite. The effect on the dissolution rate is different from Al2O3 and SiO2, because SiO2 promotes the formation of calcium silicate but Al2O3 promotes the formation of ternary calcium ferrite. The amount of hematite into molten calcium ferrite increased linearly with increasing the immersion time. The dissolution rate of solid hematite into molten calcium ferrite was mostly determined by the dissolution reaction of solid hematite at the reaction interface and the effect of the revolution speed on the amount of dissolved hematite can be negligible. Therefore,the dissolution reaction of solid hematite was the rate-controlling step under the condition of this study.