Carbonized Steel-Smelting Slag Is a Promising Raw Material for the Production of Artificial Concrete

Obtaining an artificial stone based on steel-smelting slag is possible as a result of carbonization of the feedstock in carbon dioxide. The feedstock - slag and carbon dioxide - are by-products from steel smelting in electric furnaces, which must be disposed of in order to improve the environmental situation in the region. The condition for obtaining the cementing ability of steelmaking slag is the preparation of a charge with certain properties and maturation technology: humidity, dispersion of the fine fraction and the maximum size of the coarse fraction, the ratio between the coarse and dispersed fractions, the concentration of carbon dioxide in the gas-air environment, temperature, pressure and flow time. carbonization reactions in the reactor, the magnitude of the pressure during the production of pressed articles, the process of stone maturation in the post-carbonization period.

Monitoring the oxygen removal process at the final stage of melting steel

This article deals with removing oxygen at the final stage of steel smelting in arc steel-making furnaces. It is shown that the remaining oxygen during crystallization forms floccules and significantly reduces the quality of the finished metal. During the subsequent metal processing by pressure on these floccules, the metal is torn apart and makes it impossible to obtain a steel sheet. Deoxidation is performed with expensive ferroalloys, and their consumption must be minimized. To achieve economic efficiency, it has been proposed to use recycled aluminum slag as a relatively inexpensive local deoxidizer. To optimize the deoxidizer consumption, a rapid analysis method was developed using the electromotive force (EMF) determination to determine the oxygen activity in liquid steel. As a result of the study, the composition, structure, and technological parameters of deoxidized steel were determined. The use of this technology in production will make it possible to obtain high-quality steel and improve environmental protection through secondary aluminum waste.

RESEARCH THE INFLUENCE OF COMPONENTS CARBON OXIDE COMPOSITION ON STRUCTURE FORMED METAL

The article discusses the possibility of replacing traditional charge materials for steel smelting with an oxide-carbon composition (scale-carbon briquettes) made from metallurgical waste. The possibility of replacing cast iron with briquettes for melt carburization is presented.

Study of surface defects in tubes made from nondeformed continuously cast billets

Defects of outer and inner surfaces of hot-rolled tubes of various steel grades and sizes manufactured on tube-rolling unit with a continuous mill (TPA 30-102) at Interpipe Nikotube LLC from a nondeformed continuously cast billets produced by MZ Dniprostal LLC have been studied. Characteristic genetic and morphological signs of defects were revealed which makes it possible to reliably classify them, identify cause of defect formation and recommend measures to eliminate them. Defects on the outer and inner surfaces of tubes are of metallurgical origin and associated with quality of initial continuously cast billets (a consequence of violation of the smelting and continuous casting technology). Defects on the inner surface of tubes were caused on defects in the axial zone of original billets (unacceptable porosity, looseness, chemical inhomogeneity, liquation stripes and cracks, etc.) and are classified as steel-smelting films and bulges. It was found that displacement of the thermal center of crystallization (a feature of the machines for continuous steel casting of curvilinear type) had an additional negative effect on quality of the inner surface of the studied tubes. Defects on the outer surface of tubes are tears of burning in places of accumulation of low-melting inclusions and their eutectics, as well as steel-smelting scabs on rolled dirt and gas bubbles. Likelihood of formation of scabs on outer surface of the studied tubes over rolled crust introversions is not excluded. The study results will allow manufacturers to reliably classify defects, promptly reject tubes with unacceptable defects of metallurgical origin and minimize supply of low-quality products to consumers. These results will later be included in the classifier of defects in tubes manufactured on the TPA 30-102 unit from nondeformed continuously cast billets. The results of the study of natural signs of defects of metallurgical origin in the tube surface will be useful for elaboration of measures aimed at improvement of the technology of manufacturing initial tube billets. Keywords: tube surface defects, continuously cast billets, microstructure, rolled contamination, low-melting inclusions, eutectic, gas bubbles, decarburization, liquation.

JUSTIFICATION OF THE USE OF METALLURGICAL SLAGS AS A BACKFILL MATERIAL FOR QUARRY CAVITIES

Purpose. Experimental studies of the interaction of blast-furnace and steel-making slags with open pit waters during their direct contact and assessment of the volume of filling of the formed man-made cavities during mining of mineral deposits. Methods. Based on the analysis, the current low level of metallurgical slag and the lack of real and effective directions of their large-scale utilization were determined. The laboratory studies of the interaction of metallurgical slags with open pit water at a certain time of interaction, generally accepted methods for studying the chemical composition and concentration of substances in water, computer-aided design software packages and drawings to determine the volumes of the open pit mined-out area were used. Results. The dynamics of changes in the products of interactions of steel-smelting slags with open-pit waters at a certain ratio and period of interaction was investigated. It was found that the concentration of pollutants upon contact of water with steel-making slag changes according to polynomial dependences on the time of their interaction, decreasing by the 30th day, which eliminates the danger for the aquifer. The safest type of metallurgical slag was recommended for the formation of the bottom layer of the backfill massif. The volumes of the mined-out area of the open pit were determined in detail to assess the volumes of placement of the backfill material based on metallurgical slags. Scientific novelty. The safety of the contact of backfill materials based on steelmaking slags with open pit water was scientifically proven, which is confirmed by the established polynomial patterns of changes in concentrations and pollutants from the ratio and time of interaction. Practical significance. The formation of the backfill massif on the basis of blast-furnace dump and steel-smelting slags will allow achieving an environmental effect, such as their safe disposal as a reclamation of technologically disturbed lands by mining and restoration of the economic value of the land plot, as well as preventing the formation of new dumps.

Development of Supplements Prevention System in Oxygen Converter Process in Order to Increase the Economic Efficiency of Steel Melting

The article analyzes the work of the oxygen-converter shop of PJSC «ArcelorMittal Kryvyi Rih». It is shown that almost half of the total number of blowing supplements (~ 44%) is carried out by temperature. In order to improve the conditions of steel smelting and reduce resource costs, calculations were performed and new technological solutions were found in steel smelting to reduce the number of additives. The study of real smelters demonstrated the need for corrective operations in the smelting of steel using scrap metal of different types. Scrap smelts have a clear relationship between the amount of scrap in the charge and the temperature of the melt in the first dump. The addition of «goat» scrap to the charge has a number of uncontrolled effects on the process due to significant fluctuations in the chemical composition of this type of metal charge. An economic analysis with introducing the developed control mechanism over the course of steel smelting into the software system for conditions PSJC «ArcelorMittal Kryvyi Rih» was performed.