Charge Optimization of blast furnace

Charge Optimization of Blast Furnace

From Iron Ore To Pig Iron

Optimizing the quality of the charge is to improve the quality of the charge, that is, the iron content of the ore into the furnace is high, the amount of slag produced by the blast furnace is small, and the metallurgical properties of the raw fuel are good. It is hoped that the ore grade of the large blast furnace is ≥58%, the charge contains low SiO2, low Al2O3, and low MgO, the blast furnace slag ratio is below 300kg/t iron, the M10 of coke <7%, and the reactivity (CRI) ≤25% , the strength after the reaction is ≥65%, etc., which is a necessary condition to ensure high efficiency, low consumption and large coal injection in blast furnace production

Iron-making workers at home and abroad have recognized that blast-furnace iron-making is based on concentrate. The impact rate of concentrate technology on blast furnace production indicators is 70%, the impact of foreman's operation level accounts for 10%, the modern management level of the enterprise accounts for 10%, the equipment operation level accounts for 5%, and external factors (power, supply, upper and lower processes, etc.) 5%. Under the condition of high smelting intensity and high coal injection ratio, the influence rate of coke quality change on blast furnace index is about 35%.

The content of concentrate technology includes eight aspects: high, cooked, stable, average, small, clean, few and good.

(1) High: the ore into the furnace has high iron content, high raw fuel drum strength, and high sintered ore basicity.

The high iron grade of the ore entering the furnace is the core of the concentrate technology. Its function: when the ore entering the furnace is 57%, the grade will increase by 1%, the coke ratio will decrease by 1.0%~1.5%, and the output will increase by 1.5%~2.0%. The amount of iron slag is reduced by 30 kilograms, and 15 kilograms of pulverized coal is allowed. When the iron grade of the furnace is about 52%, the grade is reduced by 1%, and the fuel ratio is increased by 2.0% to 2.2%. The high basicity sinter has a basicity of 1.8~2,2 (times), and the drum strength of the charge is high and the reducibility is good. M40 of coke ≥ 83%, compressive strength of pellets ≥ 2500 N/ball, etc.

⑵ Cooked: refers to the ratio of clinker (sintering and pellets) into the furnace is higher, generally > 80%. The clinker ratios required for blast furnace production with different volumes are shown in Table 3.

(3) Stable: The quality and supply of raw fuel into the furnace should be stable. It is required that the iron content of the charge fluctuates ±<0.5%, the alkalinity fluctuates ±<0.08 (times), the FeO content fluctuates ±≤1.0%, and the pass rate is greater than 80%~98%.

⑷ Uniform: The granularity of the raw fuel entering the furnace should be uniform.

⑸ Small: the particle size of the raw fuel into the furnace should be small

⑹Clean: The raw fuel entering the furnace should be clean, the particle size less than 5mm accounts for less than 5% of the total, and the particle size of 5~10mm accounts for less than 30% of the total.

⑺ Less: The raw fuel into the furnace contains less harmful impurities.

⑻Good: The metallurgical properties of iron ore are better: high reducibility (block ore>60%, sinter>80%, pellet>60%), high soft melting temperature (above 1200 ℃), soft melting temperature range Narrow (100~150℃), low temperature reduction pulverization rate and expansion rate are lower (first class <15%, second class <20%), etc.