Experimental Investigation on the Strength of Fluxed Pellets Made by Medium-SiO₂ Concentrate

In the ironmaking process, using a high proportional pellet is a good way for energy saving. In order to maintain the basicity and MgO content of slag, CaO and MgO are necessary fluxes of pellets while the proportion of pellets in the furnace is increased. Limited by resource conditions, many iron and steel enterprises, especially in China, do not have enough low-SiO₂ concentrate. Therefore, by preparing medium-SiO₂ fluxed pellets with different basicity and w(MgO) conditions, the influence of basicity and w(MgO) on the compressive strength of green pellets and fired pellets and the mechanism were investigated. The experimental results show that (1) in the case of w(MgO) = 0.5%-2.0%, the compressive strength of the fired pellets first increases and then decreases with the increase in basicity. As the basicity R = 0.5, the strength of the fired pellets is the highest. (2) In the case of basicity R = 0.0062-2.0, the compressive strength of the fired pellets decreases with the increase in MgO content. As the w(MgO) = 0.5, the strength of the fired pellets is the highest. (3) The optimum basicity is 0.5 and w(MgO) is 0.5%. Under these conditions, the compressive strength of green pellets and fired pellets can meet the requirements of blast furnace operation. The purpose of this research is to provide a theoretical basis for determining reasonable flux parameters and expand the range of iron ore resources for fluxed pellets.