Using of aluminium slags and products of their pro‑cessing in metallurgical production

The work contains the results of the analysis of technical literature and author’s research on the use of aluminium slags and products of their processing in metallurgical production. It has been shown that the bulk of reagents derived from secondary aluminum production wastes (APWs) are used with increased sodium and potassium chloride. This creates some inconvenience for out‑of‑furnace steel treatment due to the increased chloride content in the working area. It is proposed for steel processing to use APWs formed during flux‑free melting or dump aluminium slags. This allows to reduce the content of salt fluxes residues to 1.0–1.5 % and to improve working conditions at ladle furnaces when liquefying refining slags.

Prospects for using boron in metallurgy. Report 2

The second part of the article presents perspective directions of using boron and its compounds in the preparation processes, metallurgical processing of ore materials and steel smelting in order to improve the quality of the final product. An efficient technology of silicothermal production of ferrosilicoboron containing 0.6 – 2.0 % B and 60 – 80 % Si has been developed. The advantage of this scheme is the possibility of obtaining a boron-containing alloy during ferrosilicon smelting. It has been experimentally shown that ferrosilicoboron has higher performance characteristics than ferroboron both in production and when used for steel processing. The results of industrial tests of the technology for microalloying pipe grades of steel with a new ferroalloy with boron confirmed a high degree of boron assimilation – up to 96 %. The possibility of widespread use of boron for steel microalloying is due to its cheapness, availability and environmental friendliness. According to the calculations, boron from complex ferrosilicoboron is the cheapest trace element used to increase the strength characteristics of steel. Additives of B2O3 can be successfully used to form high-magnesium liquid steel-making slags. It is shown that 0.37 – 0.55 % В2О3 effectively stabilizes the highly basic slags of the steel and ferroalloy industries. This operation allows obtaining a marketable lump material. The above review, results of the laboratory and industrial studies have shown the effectiveness of boron usage at different stages of metallurgical production. An increase in technical and economic indicators of production and quality of steel and ferroalloys, and effective disposal of waste slags is shown. The technical solutions advanced and tested at metallurgical enterprises do not require capital expenditures. They are implemented by adding microdosing of boron and its compounds to metallurgical production facilities.

Performance management within the Dutch steel processing industry

Purpose A comprehensive literature review of performance management within the Dutch steel processing industry is presented. The purpose of this paper is to analyse the motives for companies to become excellent performers in their field of expertise. These internal and external motives (refined by quantitative analysis of bibliographic data) sought to reveal the common factors that impact company performance. Design/methodology/approach Inductive reasoning was adopted using an interpretivist philosophical stance to generate new theoretical insight. A mixed-methods analysis of pertinent extant literature afforded greater synthesis of the research problem domain and generated more valid and reliable findings. The software visualisation of similarities viewer was used to conduct a qualitative bibliographic analysis of extant literature to yield greater clarification on the phenomena under investigation. Findings Four thematic groups of past research endeavours emerged from the analysis and were assigned appropriate nomenclature, namely: industry internal motives; industry external motives; excellent performer and incremental working method. To further expand upon the continuous improvement process (CIP – embodied within performance management), the paper describes the virtuous cycle of improvement, which consists of the consecutive steps of “planning”, “doing”, “checking” and ultimately of “acting” accordingly to the previous steps. It can be concluded that a high-performing company acts according to its mission, plans in line with the vision do as defined in the strategy and checks by reflection. Originality/value This unique study provides invaluable insight into the performance management of Dutch steel processing companies. Although the research context was narrowly defined, the findings presented are equally applicable to clients, contractors and sub-contractors active in other sectors of the construction industry. The research concludes by prescribing factors of mitigation strategies to support chief executive officers to focus on the optimum distribution of their scarce resources.

Development of a Fast Modeling Approach for the Prediction of Scrap Preheating in Continuously Charged Metallurgical Recycling Processes

Improving the overall energy efficiency of processes is necessary to reduce costs, lower the specific energy consumption and thereby reduce the direct or indirect emission of gases that contribute to climate change. In many metallurgical processes, a large amount of energy is lost with the off-gas. In metallurgical recycling processes, off-gas often can be used to preheat the to-be-recycled metal scrap, leading to significantly higher energy efficiency. However, the application of preheating has the disadvantage that it often requires more precise planning in the design and better control of the process. In this paper, a simplified look at a continuously charged scrap preheating aggregate for the widely used electric arc furnace (EAF) in the steel processing industry is used as illustration. Continuous scrap charging in EAF-type furnaces in general has much higher demands on process control and general process knowledge, which is why they are found only very rarely. General issues and basic modeling approaches to mitigate such issues allowing a better process control will be described. In particular, a fast, one-dimensional modeling approach for the determination of the temperature distribution inside a constantly moving scrap bulk, with hot air (or exhaust gases) flowing through it, will be described. Possible modeling applications, assumptions, possible enhancements and limitations are shown. The first results indicate that this approach can be used as a solid basis for the modeling of scrap bulks with thermally thin parts, consisting of materials with similar thermodynamic material properties. Therefore, as a basis, this approach may help improve the design and control of future or existing preheating devices in metal recycling processes.

EVALUATION OF THE EFFICIENCY OF USING SK30 WIRE IN STEEL PROCESSING AT THE LADLE FURNACE PLANT

The paper presents studies showing the effectiveness of the use of wire with SiCa filler in the out-of-furnace processing of steels. The efficiency of use was evaluated by calculating the contamination with non-metallic inclusions, as well as by determining the phase composition of non-metallic inclusions at the stages of out-of-furnace processing and casting. (installation bucket furnace→vacuum cleaner→continuous casting). The study found that the adjustment of the content of aluminum before casting leads to the formation of refractory inclusions of corundum - (AlO), spinels - (AlO·MgO), which are deposited on the walls of the steel filling path and worsen the spillability of steel. The use of SK30prov with SiCa filler at the final stages of extra-furnace processing (after the introduction of aluminum), leads to the modification of refractory inclusions in low-melting calcium aluminates of the type (CaO·AlO). The presence of low-melting inclusions is more preferable, since this type of inclusions is not deposited on the walls of the filling cup and does not have a negative effect on the contamination of the continuously cast billet and products obtained from them with inclusions.

Phase equilibrium occurring during low-carbon iron-based melt deoxidation with silicostrontium

At the moment, to improve quality of metal (especially low-alloyed), out-of-furnace steel processing technologies are used with complex alloys utilization, which include alkaline earth metals (ALM) in addition to silicon. Study of strontium additives effect on deoxidation and liquid steel modification processes is one of the promising areas of research in field of metallurgical technologies. Thermodynamic modeling of phase equilibria in Fe – Sr – Si –C– O system melt was carried out using method of constructing surface of components solubility in metal. Solubility surface determines stability limits of non-metallic phases formed during deoxidation, depending on composition of liquid metal of the studied system. The calculation was carried out using equilibrium constants of reactions occurring in the melt during deoxidation, as well as the first order interaction parameters (according to Wagner) of elements in liquid iron. Activity of the oxide melt components was determined using theory of subregular ionic solutions. Activity of the gas phase was calculated taking into account partial pressures. Simulations were performed for two temperatures (1550 and 1600 °C) for fixed carbon concentrations (0 (no carbon in liquid iron) and 0.1 % (low-carbon metal melt)). It has been shown that, in comparison with silicon, strontium is stronger deoxidizing agent in liquid metal. According to the simulation results, liquid oxide non-metallic inclusions of variable composition or strontium ortho- and metasilicates Sr2SiO4 and SrSiO3 (with an increase in strontium concentration) should be the main oxide phases in deoxidation products. Decrease in the temperature of liquid metal leads to changes in phase formation (formation of SrSiO3 silicate becomes possible).

Evaluation of the Possibilities of Processing High-Alloy Corrosion-Resistant Steels during Grinding Operations

The issues of processing high-alloy corrosion-resistant steels by the method of centerless cylindrical grinding are considered in the article. Experimental data on changes in the parameters of roughness and hardness of a workpiece depending on the depth of cut, the speed and the design features of a control wheel are presented. The change in the microhardness of a part depending on the depth of cut is analyzed. Much attention is paid to the study of thermal stress of the grinding process. Images of temperature changes in the cutting zone depending on the grinding wheel characteristics are shown. Conclusions in the form of practical recommendations for improving high-alloy steel processing by the method of centerless grinding are formulated on the basis of the results obtained.

DETERMINING THE SUITABLE LOCATION FOR THE METALLURGICAL AND STEEL PROCESSING INDUSTRIES IN MONGOLIA USING GIS-BASED MULTI-CRITERIA ANALYSIS METHODS

The metallurgical and steel processing industries are considered strategically important industries as they form the basis of a country's industrial competitiveness and sustainable economy.Recently, the value of minerals and demand for metals are increasing. Thus, it is essential to build a metallurgical and steel processing factory in Mongolia based on the needs of national consumption and neighboring countries market demand. Therefore, it is crucial to select a suitable geographical location for any industrial regional development based on scientific, spatial analysis and estimation. The main goal of our research study is to use MCDA and AHP methods based on GIS including natural conditions, resources, socio-economic factors and other related data to identify suitable locations for metallurgical and steel processing factories in Mongolia. In order to determine the suitable location for metallurgical and steel processing industries research team used multi criteria analysis method including the total of 28 factors: 7 factors based on mineral resources and natural resources; 4 infrastructure factors, 2 market factors, 8 socio-economic factors, and 7 natural constraint factors based on area where industries and activities are prohibited in accordance with the legislation of Mongolia. According to the research results, 9.8 percent of the total area is highly suitable, 22.7 percent is suitable, 22.4 percent is unsuitable, and 68.8 percent is constraint area for industrial and steel processing industries. The result of the study shows that our assessment is precisely overlaps (kappa coefficient = 0.84 ) with the location of existing metallurgical and steel industries and compatible with the regions where other projects and action program planning to build new industries in Mongolia.

Advanced Methods for Kiln-Shell Monitoring to Optimize the Waelz Process for Zinc Recycling

The recycling of zinc in the Waelz process is an important part of the efficient use of resources in the steel processing cycle. The pyro-metallurgical processing of zinc-containing wastes takes place in a Waelz rotary kiln. Various measured variables are available to monitor the process. The temperature of the kiln-shell is analyzed by an infrared kiln-shell-scanner. In this paper, methods are presented which eliminate external weather-related disturbances on the temperature measured by the kiln-shell-scanner using a weather model and which extend the monitoring of the regularly necessary melting process to remove accretions. For this purpose, an adapted sigmoid estimation is introduced for the melting process, which provides new information about the current process status and a forecast of the further development of the melting process. As an assistance system for the plant operator, this enables an efficient execution of the melting process and reduces downtimes.

Determining changes in the temperature field of a graphitized hollow electrode during metal processing periods in ladle-furnace

This paper reports an analysis of the process of heating a graphitized hollow electrode (GHE) during steel processing in ladle-furnace. The results of the numerical modeling of electrode operation are given. The data on the temperature field of the electrode were obtained when electricity was supplied and during periods without electrical loading. Values of the Joule heat released at electrode operation during the periods of metal heating in ladle-furnace were calculated; they amounted to 1.11–1.15 MW/m3. Coefficients of the heat transfer by convection have been calculated for the inner and outer GHE surface: 1.60 and 1.80, and 5–17 W/(m2∙°C), respectively. Values of the electrode temperature gradient in the high-temperature zone were obtained, which, for the first heating period, reached 8,286 °C/m, for the third ‒ to 6,571 °C/m. It was established that during the cooling periods of the electrode, the temperature gradient is significantly reduced and amounts to the inner surface of 379 °C/m; to the outer surface ‒ 3,613 °C/m; the vertical plane to the end of the electrode ‒ 1,469 °C/m. The directions to improve the installation’s thermal work and reduce its resource intensity during out-of-furnace processing of steel have been defined. It has been determined that during the periods of electrode operation with current supply, significant values of the temperature gradient are observed, which are concentrated in the end part. During the periods of operation without current supply, a locally overheated zone forms, taking the shape of a torus flattened along the axis, which is created as a result of the accumulation of heat from the preceding period. The data have been acquired on the effect exerted by the gas supply through a hollow electrode on the parameters of formation of the high-temperature GHE regions. It has been shown that the supply of neutral gas through a graphitized hollow electrode at a flow rate of 0.05 m3/min shifts the high-temperature zone to the periphery by 3.5–4.2 mm, as well as reduces its height by 1.0–1.2 mm. The study reported here could make it possible to calculate expedient gas and material consumption for controlling the oxidation of metal and slag, to reduce the consumption of graphitized electrodes, to bring down energy- and resource costs for metal production