Influence of low temperatures and the limited consumption of lime on the operation of sinter machines at the SP-5 of PJSC MMK in winter conditions

Abstract

Lime is the only additive that has shown high efficiency in the sinter production due to the double effect on the sintering process: improving the granulation of the mix and its heating. At the sinter plant No. 5 of PJSC “MMK”, a rational ratio was established between the lime consumption of 0‒10 mm fraction supplied to the closed blending storage of mono-mix, and a fraction of 0‒3 mm, supplied to the charge room after its additional blending arrangement. During the previous research period (November 2022), the air temperature in blending storage did not fall below 6 °С, and the moisture of iron ore raw materials was maintained at the level of 3.5‒4.0%. It was recommended in winter conditions to supply lime with a fraction of 0‒3 mm to the mix department in the amount of 3% in relation to the concentrate, and the rest of the lime with a fraction of 0‒10 mm to the blending storage. In December of 2022 after the previous experiments the air temperature dropped to ‒25 °С. It was necessary to additionally estimate the minimum content of lime fraction 0‒10 mm in iron one concentrate in the storage, preventing its freezing. In this study, it was found that a decrease in air temperature over several days to ‒25 °С with a lime fraction of 0‒10 mm in the blending storage in relation to the concentrate of only 1.5% did not cause problems with flow ability and intake of iron ore con-centrate. In addition, after the start-up of sinter plant No. 5, the lime content in relation to the concentrate consumption was maintained about 5%, and the effect of its consumption on the productivity of sinter machines was not determined. As installed the decrease in productivity of sinter machines, as a result of a break due to frost in the supply of the rest of the lime by pneumatic transport to the mix department, was 12%. The influence of the basicity of iron ore on the degree of removal of sulfate sulfur in the sintering of charge was also clarified