Seznam abstraktů 2016: POSTEROVÁ SEKCE A
Datum: 26.5.2016
Use of the control-steering systems in blast furnace technology contributes to the improvement of the quality of hot metal, which can be expressed by desirable and stable chemical composition and required temperature of hot metal at the tap. The paper presents the possibility of using artificial neural network as a part of the BF technology supporting system, and in particular its use to predict silicon, sulfur and phosphorus containing in hot metal. The models of neural networks have been created on the industrial operation basis of blast furnace No. 5 Arcelor Mittal Poland Krakow.
Fluxes (slug-forming additives) provide the formation of blast-furnace slag of suitable chemical composition. These additives affect not only the technological parameters of the blast-furnace process. Fluxes must have good desulphurisation ability and low viscosity. Metallurgical enterprises in the Czech Republic mostly use acidic ore raw materials. Therefore alkaline (basic) fluxes are exploited in iron working. A frequently used raw material for the preparation of alkaline additives is dolomitic limestone. However, this material can be evaluated by a number of features that significantly influence the blast-furnace process. These properties can then be included in chemical, physical and technological categories. To evaluate one alkaline raw material, it is possible to choose a wide range of parameters. However, it is necessary to propose a principle of evaluation of these raw materials using a complex indicator which will quantify all the key parameters. The article deals with the possibility of evaluating the quality of alkaline raw materials used in the blast-furnace process.
At present time, the heat treatment process plays an important role during the production of automobile parts. This is valid especially for transmission components. During the last few years it is possible to see increasing requirements for these components. The main aim of the heat treatment, in case of transmissions components, is to improve the desired properties of the final product. This is primarily to increase the hardness and resistance to wear of such components and thus to prolong their lifetime. This paper compares two methods of heat treatment. The first method is oil hardening and the second hardening in gas pressure. The production quality, process timing, required temperature and operational costs are set up as basic evaluation criteria. On the basis of this analysis the suitable method for mass production of gearbox components is recommended.
Strong competition, steadily rising prices of raw materials and energy forces metallurgical companies to increase the efficiency of production processes. Among the key feedstock blast furnace process includes metal-bearing materials. The most voluminous part of the metal-bearing blast furnace charge consists of raw material, which is necessary before their use in the blast furnace process to adjust. In the Czech Republic mostly the sintering processes are used for preparing a metalliferous charge. Sintering process can be characterized as a continuous process, which can be of fine-grained materials produce agglomerate lump suitable for pig iron production in a blast furnace. The agglomerates made must meet the requirements in terms of both chemical and physical properties. High demands are today placed on the cost of the entire process. One option to increase the technical and economical parameters of the sintering process is dosage of coarse sinter on sintering strands. This coarse sinter is also called as sinter grate. This article aims to assess the impact of the use of this feedstock in the sintering process. Within the article are analyzed data from the research carried out in selected metallurgical company in the Czech Republic.
The characterization of non-metallic inclusions is of great importance in the production of metal and alloys. The precise determination of their size, abundance, shape and chemistry is of crucial interest to control and to improve production and quality of steel or other alloys. For two years, a combined research team including ERAMET RESEARCH and AUBERT & DUVAL has developed a new characterization method based on automated SEM measurements. This method developed with a long standing expertise allows analyzing centimeter-sized samples within a few hours. Each inclusion with a diameter larger than two microns is detected and analyzed. A fast BSE measurement coupled with EDS analyzes, calibrated with a microprobe, enables to establish precisely, for each inclusion, its size, morphology, chemistry and mineral composition. The main advantage of this method, in comparison with the other commercial applications, is that with increasing inclusion size, the amount of chemical analyses can be increased. It is even possible to determine the compositional evolution within large inclusions. In particular, these data are used to plot inclusion compositions on thermodynamically derived phase diagrams. It is possible to establish the evolution based on variations in inclusion chemistries during a process. This method is efficient, both on samples originating from liquid metal sampling and on forged samples.
Series of thermal analysis measurements by Differential Thermal Analysis (DTA) and Direct Thermal Analysis (TA) were performed on two real grade medium carbon steel samples in low and high temperature regions. Temperatures of eutectoid transition (TE), end of α-ferrite to γ-austenite transition (Tα→γ), solidus (TS), peritectic transition (TP), liquidus (TL) were determined. The stability and reproducibility of the results were verified by statistic evaluation and discussed with theoretical calculation carried out by Solidification Analysis Package (IDS) and Thermo-Calc™ (2015b, TCFE8; TC) software.
Presented research focused on high silicon cast iron with 19% silicon content. The studies were conducted in two steps. In the first step the crystallization process analysis using TDA method was executed, metallographic examination on optical microscope was made and calculations in Thermo – Calc were performed. Two different intermetallic phases were noticed in cast alloy: Fe5Si3 and probably Fe2Si. In the second step the EDS analysis on scanning electron microscope was conducted, which proven the occurrence of primary Fe2Si precipitation. These phases significantly affect the quality of high silicon cast iron.
The publication attempt to investigate the effect of heat treatment parameters, the impact of ADI. Ductile iron tempered with isothermal transformation according to two variants. Both variants of heat treatment consisted of a two-stage austenitising. Iron cured at tA = 950 0C gradually cooling to a temperature of the supercritical tA '= 850, or 800 0C (in the latter case). Isothermal transformation carried out under the same conditions. Isothermal hardening was carried out at 300 or 400 0C and resisting the time of from 7.5 to 240 min. In the studies the impact breaking of the sample was notched. The results were compared with values given in the standard BS EN 1564: 2012.
Despite the development of steel making technologies a significant portion of deoxygenation reactions products remain in the molten metal until the time of casting. These ration products are referred to as non-metallic inclusions and their dimensions lower than 30 μm. Years of research, both in laboratory and in industrial environment, showed that these type of inclusions can be removed using multi-holed ceramic filters. Additionally, filters can, when used in continuous steel casting installations, reduce the risk of clogging of tundish nozzles. Clogging is frequent problem during casting of steel deoxidized with aluminium. In this situation the outlet may act like ceramic filter when non-metallic inclusions are deposited on its edge. In effect, this results in the need for early termination of the casting process. Paper presents the results of studies on this phenomenon.
This article deals with production technology and secondary metallurgy processing of tool steels in electric steelworks of VHM a.s. with the focus on thermal and slag regulation of heats. During the production and secondary metallurgy steel processing of a trial heat so-called „programme thermo-time steel processing technology“ (PTVO) was used.
In its evaluation, the attention was mainly focused at the steel production – technological parameters of 100CrMo7 steel. At the trial melting based on the liquidus temperature, the optimal degree of overheating of the steel melt, and also in the framework of the evaluation there was also performed comparison with the thermal regime of heats of the same kind of steel with common technology.
When evaluating the slag regime, the attention was focused mainly on the composition of refining slags and the course of desulphurisation of the steel melt.
Designing the physicochemical properties of consumables used in the steel industry they must be tailored to the technical and technological parameters of the production equipment. Proper properties designing of the consumables used in the production line allows you to receive a high quality final product. The article shows the use of a model for designing the physicochemical properties of mould powders that meets the requirements of local process conditions of COS device, based on the developed in recent years empirical rules. The model determines the physicochemical properties of mould powder on the basis of established procedures and successive logical steps, which include solving such issues as: the appropriate classification of the cast steel to a type group, optimizing the parameters of oscillation and lubrication conditions for the selected cross-section of the mould and determining the optimal values of three physical parameters of mould slag: alkalinity, viscosity, and crystallization temperature (breakthrough). The final composition of the powder is set as a result of multiple calculation of the above phisical qualities until reaching the result closest to the pre-estabilished values. Preliminary calculations indicate that the model correctly describes the chemical composition of the powder for carbon and low-alloy cast at standard speeds in flat ingots.
The agitation of melt in the hearth furnaces is complicated. It depends on introduced system of technological gases blowing, the shape of working profile of the hearth and a degree of hearth lining wear in the course of furnace campaign. In many cases it is insufficient. The results of experimental study on physical models of hearth furnaces with the considered variants of the blowing system are influenced by incomplete similarity of used physical quantities – dissimilarity in invariants of density and viscosity of melt with the model and the real hearth furnace. That is why it was concerned with the mathematical modelling of agitation effects of selected blowing variant on the movement of melt in the furnace hearth. The results of mathematical modelling of melt movement in the considered variants of blowing may serve not only for the selection of most suitable configuration of blowing system or blowing variant for the given furnace and conditions, but also, among others, to the prediction of erosion effects of flowing melt on the refractory lining of furnace hearth depending upon the gradient of velocity of melt flow in the vicinity of walls of furnace lining.
The aim of the study was to determine the detection possibilities for corundum in slags. Corundum may be a harmful component in the secondary utilization of slag. To determine the occurrence and amount of corundum in slag, gravity concentration was used (using the specific weight differences) on tables. The first step of the partial work was detailed characterization of the material using mechanical and physical parameters, including, for example, particle size distribution or friction parameters. In the practical part, the material was first re-sorted. Subsequently, it was examined whether gravity concentration can be used to analyse corundum particles in slags. Individual tests were performed on water and pneumatic plate. Finally, the samples were floated. Some conclusions of the experiments suggest that gravity concentration can be used on plates to capture and analysis corundum minerals in these samples of slags. The quantity of the particles obtained and their size depended on the type of technological treatment. This method has been tested and applied in the laboratory of a company dealing with slag treatment.
Radiation heat transfer between two bodies is mathematically a surface integral whose integrand is again a surface integral. The analytical solution of this problem is therefore possible only in special cases. This article deals with one of these cases and includes a proposal to simplify the calculation of some of the local view factors in the crucible furnace. The view factor is the basis of the internal integral above problem. The proposed calculation is based on the fact that the outer surface of the crucible and the inner surface of crucible furnaces are rotational surfaces with a common axis.
The problem of environmental pollution due to increased industrial activity is the subject of attention in the country and around the world. The main purpose of waste management should be reclamation of valuable raw materials and, consequently, protection of natural environment by reducing consumption of deposits and energy. The metallurgical industry generates considerable quantities of waste containing iron i.a. dusts from the electric arc furnace (EAFDs). EAFDs are among the most troublesome products of electric steelworks. Possibilities of EADs depend, among others, on their chemical composition. This article presents the results of the chemical composition of EAFDs from the steel mill and foundry.
The application of wire scrap from tyre recycling can be very important especially when the steel is melted in induction furnace. However, in the induction furnace there is no possibility for decarburization od steel because of the danger of lining erosion, and as a result unavoidable furnace failure due to liquid metal leakage. Thus, this operation can be moved outside the electric furnace, to the ladle. Proposals of such solution are found in literature, especially with application of blowing the liquid steel by the gas-oxygen mixture through the bottom of the ladle and the further secondary treatment in ladle furnace.
Such innovative way of decarburization of liquid steel in ladle with blowing by gas-oxygen mixture through the bottom was the main object of the presented research. The aim of this research, conducted on the physical model, was the preliminary identification of hydrodynamic conditions caused by the intensive mixing of modelling liquid by the gas. During such research it was observed the mechanism of gas bubbles cone creation. The following parameters are also very important: the level of gas bubbles dispersion in the modelling liquid, behavior of the modelling liquid surface as a result of flowing out gas bubbles, and the flow rate of occurring breakouts of modelling liquid above the height of modelling liquid surface.
The main objective of management of waste is to recover valuable component (eg., metals, energy). Thanks to the use of waste as raw materials in certain industrial processes their storage is avoided, and also it creates the possibility of liquidation of existing landfills. A characteristic feature of the tested waste - the steel industry sludge - is significant iron content. This article presents the results of chemical composition of the sludge deposited and from the current production. Knowledge of the chemical composition of the waste is the basis of possibility of their further development.
Chromium content in the alloyed steels is generally between 8 to 30 wt. %. During the melting of steel charge containing chromium, its loss by the oxidation and its transition into slag at steel production in the EAF occurs. The first losses already occur during the charge melting in the EAF but the main part of the chromium loss from the melt occurs during the oxidation phase when oxygen is blown with the aim of ensuring of basic refining reactions and melting decarbonisation. The high content of chromium in the slag influences its properties, it is connected with the creation of slag crust with the high viscosity which decreases the slag reactivity and prevents it from creation of foam slag during steel production in the EAF. Reduction of chromium oxides from the slag at melt treatment in the EAF depends on the choice of appropriate reduction agent and applied reduction technology. In the presenting paper, the results of laboratory experiments aiming the study of chromium and its oxides behaviour together with the mechanism of its reduction by the help of silicon and carbon are given. Experimental heats were aimed to the proposal of theoretical calculation of consumption of chosen reduction agents, reduction study in the laboratory conditions at the application of alloyed steel with the chromium content of ca. 9 wt. %, 13 wt. % and 18 wt. %, temperatures 1 600 °C and 1 650 °C together with the change of amount of reduction agents and the reduction period. Results will be used for results verification obtained during half-operational and operational experiments whose will imitate the operational conditions in the EAF.
The article presents the results of abrasion tests for different types of silicon cast iron. Scope of research included silicon cast iron with a silicon content in the range of 15 - 25%. Wear resistance studies were based on gravimetric method, where the sample was moving reciprocally in metal – mineral friction system. As a material for countersample silicon carbide was used. Obtained results allowed to determine the wear resistance of alloy cast iron and the relation between wear resistance and silicon content in the alloy for selected work conditions.
The methods for determination of solidus (TS) and liquidus temperatures (TL) in high-temperature region for selected steel grade were compared in the frame of this paper. The paper deals with discussion of the results obtained by the two different simultaneous methods of high-temperature thermal analysis (Direct Thermal Analysis and STA) on the high-sophisticated specialized experimental systems (Netzsch STA 449 F3 Jupiter, Setaram SETSYS 18TM,). The as-cast steel with large diameter (350 mm round format) from continuous casting was studied. Based on above mentioned dynamic thermo-analytical methods the TS and TL temperatures under different heating/cooling conditions were determined. On large samples (approx. 21 g), the method of direct thermal analysis (DirTA) in conditions of linear heating and cooling was applied. On small samples (150 mg), the experiments using differential thermal analysis (DTA) in conditions of linear heating were realized. Data acquired from thermo-analytical measurements were then compared with values calculations by specialized programs (ThermoCalc and IDS database) and with liquidus temperature currently defined in practice for continuous casting of discussed steel grade.
DSC method (Differential Scanning Calorimetry) is one of the thermal analysis methods which is suitable for studying the thermodynamic properties of metallic systems. In this work the heat capacities of real steel grade in the solid phase under strictly defined conditions for controlled heating were studied. The paper deals with the investigation of real steel grade in the solid phase under strictly defined conditions for controlled heating. Heat capacity of steel was obtained using high-temperature calorimeter Setaram MHTC 96 (Multi High Temperature Calorimeter) with 3D DSC sensor. Experimentally acquired heat capacity ("Apparent Heat Capacities") of real steel grade were confronted with the calculated theoretical data (software Thermo-Calc) and with data reported in the available literature.