Influence of the size of hematite and magnetite ores on the parameters of the sintering process and the quality of the sinter

Laboratory sintering of sinter charge based on hematite and magnetite iron ores of various sizes was carried out. The purpose of the study was to determine the effect of the type and size of the ore material on the gas permeability of the sintered layer, sintering performance and the need for fuel. The granulometric composition, cold strength, strength during recovery, and reducibility of the resulting agglomerate have been studied. Differences in the course of the process of agglomeration of hematite and magnetite ores at different sizes were revealed in the research. The established patterns have practical interest from the point of view of increasing the efficiency of the sintering process, improving the quality of the sinter and reducing the harmful impact on the environment.

Influence of Biomass Absorptivity on the Process of Sinter Charge Pelletisation

Capillary water absorption of materials is a very important factor in the process of pre-treatment of fine-grained materials. Materials that are in a moisturized state capable of forming a firm, compact pellet are, thanks to this particular physical property, suitable for utilisation in sinter charge preparation within the process of sintering iron-ore raw materials. The pelletising ability of coke dust is generally known and coke dust exhibits good pelletisability. From the ecological point of view, an alternative to coke dust is currently biomass, which has a great potential for industrial applications, including use in the agglomeration process. Understanding of how biomass behaves during pre-pelletisation is very important and for the sintering process, it is essential. The purpose of pre-pelletisation of the sinter charge is to achieve its optimal permeability in the sintering process. The experiment described in the article was carried out using wood biomass—oak and pine sawdust, as well as plant biomass—Miscanthus sinensis and Lavandula angustifolia. The evaluation was carried out by applying the capillary water absorption test and the free-fall drop test. As different types of biomass have different chemical compositions, heating capacities, grain morphologies, and chemical and physical properties, the testing was carried out with several types of biomass. The capillary water absorption was examined in terms of different granulometries, and the impact of the type of liquid medium was analysed. It was observed that different types of biomass differ in their ability to absorb liquids. Another finding was that the type of a liquid medium had a significant effect on the pelletising ability of biomass, which was determined by the surface tension and the ability to form liquid bridges between the grains. Research results indicate an excellent pelletising ability of the Miscanthus sinensis grass. The wettability of oak and pine sawdust determines its application in the pelletising process. It may be concluded, based on the research, that Lavandula angustifolia is not a suitable alternative to coke dust due to its low ability to form pellets.

Analysis and synthesis of factors determining the sintering speed of sinter charge

The main objectives of the study are the analysis and generalization of the parameters that determine the intensity of the sintering, the development of a model of motion of the combustion zone of the sinter charge. As a result of the analysis of the known indicators of the intensity of the sintering process, it was shown that the most representative characteristic of the intensity of the process is the vertical sintering speed, which is an integral part of the complex intensity indicator − the specific productivity of the sintering machine. Many various models of the sintering process have been developed. The author develops a new mathematical model of the motion of the solid fuel combustion zone during sintering of the sinter charge (vertical sintering speed). The model is presented in the form of an expanding network of separate interrelated dependencies (equations), selected as independent submodels. The results of the study using the developed model of the dependence of the vertical sintering speed on the solid fuel content and on the flux content in the charge, are presented. It is concluded that the presented model can be considered as an element of a universal model software complex of the sintering process.

Automatic System Design Humification of Sinter Burden in Aglomeration Shop JSC «Ural Steel»

The authors propose a comprehensive solution to decrease in humidity control sinter charge sinter shop JSC Ural Steel. The main task of sinter production is the maximum productivity of the sinter machine with a sat-isfactory agglomerate quality. One of the key parameters affecting the sinter belt performance is the moisture content of the humidity sinter. Changes in the granulometric and chemical composition and physical and me-chanical properties of the components of the charge necessitate the search for new values of the optimum hu-midity of the charge. A system for automatic control of sintering machine productivity has been developed. Au-tomatic control is based on the principle of operation of a stepping type extreme regulation system with memo-rizing the extremum (maximum) of the output parameter. The simulation of the pump electric drive is implement-ed based on the developed automatic control loop for the moisture content of the sinter charge. Implementation of the proposed system for automatic wetting of the sinter charge will increase the productivity of the sinter machine by 1,4 % while reducing the water consumption by 1,7 %.

Improving the technology production of quality agglomerate

Purpose. The existing technological scheme of agglomeration does not allow obtaining a amount of agglomerate stabilized by size and strength with a small amount of trifle. The aim of the work is theoretical substantiation and development of measures to improve agglomerate production technology in modern conditions on the basis of the results of the study of effective methods of separate preparation of the charge before sintering, as well as methods of mechanical processing of sintered agglomerate in devices of special construction. Methodology. The analysis of the basic thermodynamic parameters and phase composition for the components of the sinter charge was carried out using the software complex HSC Chemistry 5.11. Investigation of the effect of separate preparation of the charge with the use of pre-prepared composites on the parameters of sintering and the quality of agglomerate was carried out in the laboratory of the department metallurgy of cast iron NMetAU at the aggregate for sintering. The determination of the effectiveness of the proposed measures was carried out by mechanical processing of agglomerates obtained after the classical and proposed scheme of preparation of the charge. The quality of the obtained agglomerate was estimated using indicators: uniformity of the granulometric composition, content of trifles, strength indicators after discharge to the steel plate [DSTU 3199-95], coefficient of shape of pieces of different sizes, chemical composition. Findings. It has been determined that the use of separate preparation of the charge has a positive effect: significantly decreases the amount of fraction 0-1 mm and increases the equivalent diameter of the granules; diminishes the mean square deviation and variation coefficient, indicating a more homogeneous granulometric composition of raw granules. The efficiency of separate preparation of a charge with the use of composite with the basicity of 0.9-1.0 is confirmed from a concentrate (size 0-0.1 mm), iron ore (0-3 mm), lime (0-3 mm) and limestone (0-3 mm) and residual blend with the basicity of 1.6-1.8 from iron ore (3-10 mm), sinter return (0-10 mm) and limestone (0-3 mm). Originality. The idea of interaction of different components of agglomeration charge during the separate processes of humidification and laceration is developed. The possibility of forming more homogeneous in size and composition of granules is substantiated, by their separate origin not only around large pieces of backs and ores, but also due to the separate interaction of small components with active surface properties, and subsequent joint granulation of the embryos of granules with the residual charge. It is shown that depending on the given conditions, at the stage of separate preparation of the charge, a binder part is formed predominantly of iron-calcium olivines and calcium ferrites. Practical value. Technological recommendations for increasing the efficiency of preparation of sinter charge to sintering and practical recomendations for the design and technological parameters of the drum-stabilizer work, which ensures the stabilization of agglomerate.

Efficiency Improvement of Sintering as a Result of Surface-Active Substance Use in Pelletizing at the JSC "Ural Steel"

A set of pilot experiments to improve pelletizing through the use of the sinter charge humidification of water-soluble organic surface-active agents (surfactants) has been performed in the sintering plant JSC "Ural Steel". It has been found that the surfactant use provides an improved granularity of the sinter charge and increases its gas permeability during sintering that ensures a better technology and quality. The maximum efficiency from the surfactant use is manifested in the area of the optimum moisture content of the sinter charge (7 – 8 %) at a flow rate of the experimental binder 1.2-1.6 l/h (surfactant concentration in an aqueous solution is 0.3 – 0.4 ml/l).