Evaluation of the Quality of Low SiO2 Sintered Ore Considering Blast Furnace Operating Conditions with High Rate Pulverized Coal Injection

In order to evaluate qualities of low SiO2 sinter such as reduction degradation behavior, reducibility and softening-melting properties, laboratory tests simulating in-furnace conditions at high PCI operation were carried out using three types of commercial sinters with varying SiO2 content. The main results obtained are as follows: (1) Under high PCI operating conditions, reduction degradation of sinter is decreased. This suppression is due to the shortening of retention time in a temperature range between 500 and 600 degreesC by decreasing the heat flow ratio. This tendency of reduction in sinter degradation has been confirmed by operation trials at Fukuyama blast furnaces No. 3 and No. 4. (2) Hematite phase and micro pores increase with a decrease in SiO2 content of sinter, and consequently reducibility increases due to an improvement in reduction gas diffusion through the reduced layer. (3) The temperature at which softening, commences and that at which the pressure drop rises are higher for Low SiO2 sinter than the corresponding temperatures for high SiO2 sinter. This result suggests an improvement in the permeability of the cohesive layer in the blast furnace under high PCI operating conditions. (4) This evaluation has confirmed that low SiO2 sinter is superior to high SiO2 sinter as the blast furnace burden under high PCI operation even though the value of RDI is relatively high.