Treatment and Utilization of Converter Sludge

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Source: internal company

Steelmaking converter sludge is the product of wet dust removal of flue gas produced by converter steelmaking. Large iron and steel enterprises at home and abroad attach great importance to the comprehensive research and utilization of steelmaking converter sludge. At present, there are mainly the following three methods for the treatment and utilization of converter sludge:

1. Direct feedstock process
In other words, sludge is mixed with other dry powder and sintered ore return to be directly used as sintering raw materials. In this method, some harmful impurities have not been removed, such as ZnO, PbO, Na2O, K2O, etc. These magazines are easy to cause a vicious circle, and Na2O and K2O have adverse effects on sintering electrostatic precipitator. In addition, the chemical composition, difficulty and moisture of various dust and mud are quite different. Without special mixing process treatment, sinter quality will fluctuate, which is not conducive to the improvement of sinter output and quality. In a word, this method has a single way of utilization and a low level of utilization, which belongs to extensive utilization. In addition, in dust and mud unloading and mixing operations, the working environment is relatively poor and the pollution is serious.

2. high temperature desulfurization method
After mixing the converter sludge, it is roasted at high temperature in the rotary chamber, cooled, mixed and rolled, pressed into balls, and dried to become qualified cooling slag balls, which are used in steelmaking converters. This method can effectively remove harmful impurities such as Pb, Zn and S, and the obtained slag ball contains more than 60% iron, which can make full use of iron resources in sludge. However, this method needs to build large and complex equipment such as rotary chamber, which occupies a large area and has high investment.

3. Low temperature drying method
The sludge is batched, mixed and rolled, then pressed and formed by a high-pressure ball press, and dried at low temperature to become a cooling slag ball. The cooling slag ball produced by this method has stable chemical composition, low harmful substance content, fast slag melting speed and obvious cooling effect, and is a high-quality auxiliary additive needed by steelmaking converter. Compared with the high temperature desulfurization method, this method has the advantages of less investment in production equipment, simple process flow, less investment, convenient production operation and strong adaptability of raw materials.

The cooling slag ball produced by high-temperature desulfurization method and low-temperature drying method is a new type of burden introduced in recent years. Because of its environmental protection and energy-saving characteristics in the production and use process, large-scale production plants have been built in many countries for various smelting uses. With the wide application of this technology, by-products from smelting industry can be processed, which can not only meet the needs of steel slagging, but also turn waste into steel again, thus realizing a virtuous circle of steelmaking process. Two tons of cooling pellets containing more than 60% iron can produce one ton of steel. Adding cooling pellets in time can solve the refractory phenomenon in the steelmaking process, thus reducing the melting point of slag, ensuring good fluidity of slag, and reducing the consumption of steel fuel and lime.