A kind of production method of hypoeutectic casting pig iron

Abstract

The invention discloses a production method for hypoeutectic cast pig iron. The production method is characterized in that the pig iron comprises the following chemical elements by mass fraction: 3.400-4.000% of C, less than or equal to 0.600% of Si, less than or equal to 0.100% of Mn, less than or equal to 0.040% of P, less than or equal to 0.030% of S and less than or equal to 0.040% of Ti. The production method comprises the following working procedures: (1), blast furnace smelting: 65-70 wt% of a high basicity sinter and 30-35 wt% of pellets are taken as raw materials, and the basicity of the high basicity sinter is 1.90-2.00; during smelting, the content of Si is controlled to be less than or equal to 0.50 wt%, and the furnace slag binary basicity R2 is controlled to be from 1.15 to 1.20; (2), electric furnace smelting: an electric furnace is heated to smelt iron by utilizing a blast furnace molten iron and waste steel method; a first inoculation treatment is performed when the iron is discharged, and the addition amount of an inoculant is controlled in a range of 2-3 kg / t molten iron; (3), casting moulding: the inoculant is added along an iron flow during casting to perform second inoculation treatment, and the addition amount of the inoculant is less than or equal to 2 kg / t molten iron. According to the production method for the hypoeutectic cast pig iron, factors, such as utilization factors, yield and hot air temperature, are improved; furthermore, the comprehensive coke ratio is remarkably reduced; the problem of thick graphite heredity in casting industry is solved.

Description

technical field [0001] The invention relates to a production method of pig iron, in particular to a production method of hypoeutectic casting pig iron. Background technique [0002] According to the phase diagram of iron-carbon alloy, the eutectic point of iron-carbon alloy is 4.3% carbon content, the pig iron lower than the eutectic point is hypoeutectic pig iron, and the pig iron higher than the eutectic point is hypereutectic pig iron. Due to the blast furnace smelting process conditions, the pig iron directly smelted by the blast furnace is hypereutectic pig iron. When the hypereutectic pig iron is cast iron, the carbon in the molten iron will appear as coarse C-type graphite and rapid cooling during the solidification process. cold graphite. Coarse C-type graphite greatly reduces the strength of cast iron, and the coarse flake graphite and supercooled graphite are inherited to varying degrees during the remelting process of cast iron, resulting in the molten iron after...

AI Technical Summary

Problems solved by technology

In order to reduce the influence of bulk graphite and supercooled graphite in pig iron, there are generally two measures: one is to increase the smelting temperature to melt thick bulk graphite into molten iron, but in fact the effect is minimal, because the melting point of graphite is 4000 °C, Difficult to melt, the maximum temperature in the cupola furnace is 1700--1800°C; if the temperature of the electric furnace reaches above 1600°C, the graphite will mutate and its performance will decline, and the coarse and massive graphite in the pig iron is difficult to eliminate

Therefore, it is impossible and uneconomical to eliminate the coarse and large flake graphite in pig iron by increasing the smelting temperature

The second is to use less pig iron or no pig iron, and add more furnace materials and scrap steel. However, due to the difficulty in supplying scrap steel and the quality of scrap steel is difficult to guarantee, the quality of castings cannot be guaranteed.

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