Production practice of steelmaking sludge before iron

Steelmaking sludge is a kind of iron-bearing dust collected by converter process dedusting, which has high iron content and is a valuable secondary resource. Due to the high moisture content in the factory, there is no condition for timely use, so it has to be temporarily stored outside the pile. If it is abandoned, the waste of resources will cause environmental pollution at the same time. After the steel-making sludge stored in the open air is treated, it will enter the neutralization yard, pile into the mixed material, and be used in the iron making and sintering process.

Steelmaking sludge has strong hydrophilicity, high taste, fine particle size, high harmful elements and strong viscosity. FeO content is high, iron content is high, s content is a little high, P content is high, Pb content is high, Zn content is high.

Assimilation characteristics

The lower the assimilation temperature is, the stronger the assimilation is, the easier the formation of liquid phase is, and vice versa. The assimilation temperature is above 1260 ℃, indicating that the assimilation of the iron ore powder is weak, and the assimilation temperature is below 1220 ℃, indicating that the assimilation of the iron ore powder is strong. The assimilation temperature was 1220-1240 ℃, and the assimilation was in the middle. Generally speaking, in the process of sintering, if the assimilation is too strong, there will be a large amount of liquid phase, a wide range of bonding, which is easy to form a large pore wall structure and affect the mechanical strength of sintering. The magnetite around the pores will be oxidized twice, which will aggravate the low-temperature reduction pulverization and affect the hot gas permeability of the sinter layer. If the assimilation is too low and the bonding range is narrow, it will also affect the strength of sinter. Therefore, iron is required The assimilation of mineral powder is suitable.

The assimilation of steelmaking sludge is weak, so it is not suitable for large proportion. According to the principle of complementary advantages of basic characteristics of high-temperature sintering of iron ore powder, it is feasible to optimize the use of small proportion steel-making sludge and iron ore powder with strong assimilation characteristics.

Proportion: the proportion of steel-making sludge is 3% at the beginning. According to the actual use effect, the proportion is increased to 5%. After mixing with magnetic separation powder, the proportion is added to 8% as a new mineral. It can be added to 12% as a new kind of ore after mixing with return ore. Due to the low moisture content and close composition of magnetic separation powder, the dry material returned to the ore has a certain temperature, and the application effect is obvious.

Through the comparison and analysis of the components of the steel-making sludge used alone and after mixing for many times, the moisture content has been halved, the taste has been improved, the harmful elements have been effectively reduced, the viscosity has been greatly weakened, the frequency of the roof material in the pre batching tank has been greatly reduced, and the disc blanking is basically smooth.

Through the practice of production tackling key problems, the iron making plant has taken effective measures. It is feasible to add steel-making sludge in the iron making and sintering process according to the proportion of 5%, and it is effective to reduce the direct cost per ton of iron. Although there is a gap with the goal, the results and benefits of joint efforts are obvious.

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