Smelting of steel semi-product in BOF and EAF under magnesian slags

Basics for the development of a rational composition of the main magnesian slags and technological methods for their formation according to the periods of BOF bath blowing and the periods of smelting in EAF are the results of fundamental studies of the slags physicochemical properties. Implementation in the converter shop of OJSC “EVRAZ NTMK” of a developed set of technological methods of magnesian slags formation in the main period of blowing and a wearresistant skull on the basis of magnesian final slags ensured record durability of converter linings. These slags have low aggressive effect on the lining of converters, while maintaining high refining properties. The durability of the converters’ lining exceeds 7000 heats, while maintaining high technological and technical-economic indicators of the process. During heats of low manganese cast irons in 350-metric ton heavy converters of JSC “EVRAZ ZSMK” under magnesian slags, the features of slag formation and changes in chemical composition of the slag were studied by the periods of the BOF bath blowing. During the process stage of phosphorous cast irons in 300-metric ton BOF at JSC “ArcelorMittal Temirtau”, a set of technological methods was developed for the formation of magnesian slags of the recommended chemical composition by the periods of phosphorus cast irons blowing and wear-resistant skulls based on final magnesian slags of moderate basicity. The implementation of the developed technological methods ensured the lining stability of BOF of more than 5 000 heats while maintaining high technological, technical and economic indicators of phosphorous process stage. In the EAF shop of PJSC “Seversky Pipe Plant” a technology for the formation of magnesian slags of rational composition was developed over the smelting periods in EAF-135. Introduction of the technology ensured the record resistance of the refractory lining of the furnace up to 1900 heats per campaign and high level of technological and technical-economic indicators of the process.

BOF, EAF, lining resistance, magnesian slags, slag blowing, slag foaming, viscosity, chemical composition, phase composition

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