Combined effect of MgO and basicity varied by different dolomite and burnt lime addition on sintering performance of magnetite concentrates

Abstract

In this paper, the combined effects of MgO and basicity (CaO/SiO₂), varied by changing the ratio of dolomite and burnt lime to sinter mix, on sintering of magnetite concentrates were investigated in pilot scale. Mineralogy of sinter with various MgO and basicity was analyzed by light microscope and scanning electron microscope (SEM). The results show that increasing MgO led to lower sinter strength and higher fuel consumption, while increasing basicity behaved in the opposite way. Regardless of MgO content, minimum sinter strength occurred in basicity 1.2–1.6, which should be avoided in sinter production. Less SFCA (silicoferrites of calcium and aluminum) and more magnetite were observed in sinter with higher MgO content. Aside from hematite and magnetite, the dominant phases in sinter with low (0.8) and high (2.2+) basicity were glass and SFCA respectively. Sinter with basicity 1.6 had highest crack density and this would inevitably reduce its cold strength.