Improving the sintering performance of specularite bearing mixtures by separated pre-agglomeration-sintering processes

For the characteristics of weak ballability and inferior amenability of specularite concentrates, the granulating and sintering performances of imported specularite were investigated by two kinds of separated pre-agglomeration-sintering processes. Compared with the traditional granulation-sintering process, the separated micropelletizing-granulation-sintering process presents competitive results:decreasing the coke level from 4.85% to 4.20%, improving the productivity from 1.44 t·m^-2·h^-1 to 1.71 t·m^-2·h^-1, enhancing the tumble index from 57.60% to 63.80%, and cutting the solid fuel rate from 76.46 kg·t^-1 to 65.24 kg·t^-1. In the meantime, the separated pre-briquetting-granulation-sintering process also shows better results:decreasing the coke dosage from 4.85% to 4.70%, elevating the productivity from 1.44 t·m^-2·h^-1 to 1.64 t·m^-2·h^-1, and keeping the tumble index and the solid fuel rate steady. Overall, the separated pre-agglomeration-granulation-sintering process can significantly improve the sintering performance of specularite. The mechanism of action is that the separated pre-agglomeration-granulation-sintering process improves the permeability of the mixture markedly, decreases the coke dosage appropriately, results in a higher oxidation potential in the sintering bed, and produces more calcium ferrite and hematite finally. Meanwhile, mineral crystals in the product sinter grow perfectly and compactly, and the pores mainly develop into middle or small sized spheres from the irregular big ones, all of which contribute to the higher strength and better reducibility of the product sinter.