Stamp-Charged Coke-Making Technology—The Effect of Charge Density and the Addition of Semi-Soft Coals on the Structural, Textural and Quality Parameters of Coke

Coke is an integral component of the blast furnace charge; therefore, it plays an important role in the integrated steelmaking process. Achieving the required coke quality parameters by producers requires the use of a high proportion of the highest quality coking coals (hard coking coals) in the coking blends, which significantly increases the unit production costs. Approximately 75% of these costs are constituted by the cost of the coal blend’s preparation. There is a deficit in the best quality coking coals on the world market and their supply are characterized by large fluctuations in quality parameters. Therefore, from the point of view of the economics of coke production, it is advantageous to produce high-quality coke from a coke blend with the highest possible content of cheaper coals. The paper presents the results of the influence of coal charge bulk density and semi-soft coking coal content in the coking blend on the textural and structural parameters of coke, which determine its quality. Research has shown that the application of increased density influences the parameters of the texture and structure of the coke, which shape its quality parameters. The use of stamp-charging technology contributes to the improvement of the coke quality or enables the production of coke of a predetermined quality from blends containing cheaper semi-soft coals.

MODELING OF DISTRIBUTION COEFFICIENTS OF CHARGE ELEMENTS BETWEEN FINISHED PRODUCTS OF BLAST FURNACE SMELTING IN MODERN CONDITIONS

The results of using the developed methodology for predicting the distribution coefficients of the charge elements between the products of blast-furnace smelting based on the calculation of the integral parameters of the charge and the temperature-blowing regime for modern operating conditions of one of the blast furnaces in Ukraine are presented. The proposed approach differs from traditional methods of considering the distribution coefficients of charge elements as constant values and provides a predictive calculation of the chemical composition of cast iron and slag depending on specific charge and technological conditions when solving the problem of a reasonable choice of the composition of the blast furnace charge.

Improvement of iron ore pellets metallurgical properties by their fluxing by lime

Fluxed iron ore pellets, obtained by application of raw limestone are widely used in the iron ore share of blast furnace charge. Decomposition of the raw limestone in the process of the pellets burning requires considerable energy. The purpose of the work was to study quality variation of raw and burned pellets, as well as metallurgical properties variation, caused by substitution of limestone by burned and slaked lime. Physical simulation of the pelletizing process and pellets burning process was done. In the process of the experiment simulation of total and partial substitution of limestone by lime as well as with partial substitution of limestone by slaked lime was accomplished. Diagrams of plasticity and strength of raw and burned pellets at various shares of limestone, burned and slaked lime presented. It was shown that the strength during reducing RDI-1 (ISO 4696-1) has a tendency to increase when application of lime. Increase of Index RDI+6,3 value accounted for 3.6% (abs.) at application of quicklime and slaked lime correspondently. Index RDI−3,15 value decreased by 1.06% (abs.) and 0.88% (abs.) and that of index RDI−0,5 – by 0.75% (abs.) and 0.8% (abs.) at application of quicklime and slaked lime correspondently. It was assumed that application of slaked lime can contribute to bentonite share decrease and thus to total iron content increase. It was established that application of lime enables to decrease heat consumption for pellets burning. Application of slaked lime instead of limestone in the process of pellets production results in an increase of their strength during reducing and compression strength. This effect enables to reach a higher efficiency in the process of such pellets usage in blast furnace charge or in the process of their metallization, comparing with the usage of pellets fluxed by limestone.