Steelmaking Shop Research Articles

Technological Innovations of Carbon Dioxide Injection in EAF-LF Steelmaking

In this study, the recent innovations and improvements in carbon dioxide (CO2) injection technologies for electric arc furnace (EAF)-ladle furnace (LF) steelmaking processes have been reviewed. The utilization of CO2 in the EAF-LF steelmaking process resulted in improved efficiency, purity and environmental impact. For example, coherent jets with CO2 and O2 mixed injection can reduce the amount of iron loss and dust generation, and submerged O2 and powder injection with CO2 in an EAF can increase the production efficiency and improve the dephosphorization and denitrification characteristics. Additionally, bottom-blowing CO2 in an EAF can strengthen molten bath stirring and improve nitrogen removal, while bottom-blowing CO2 in a LF can increase the rate of desulfurization and improve the removal of inclusions. Based on these innovations, a prospective process for the cyclic utilization of CO2 in the EAF-LF steelmaking process is introduced that is effective in mitigating greenhouse gas emissions from the steelmaking shop.

COMPREHENSIVE INDEX OF QUALITY OF ROLLED STEEL AND ITS APPLICATION

The concept of an integrated indicator of quality of rolled metals, for example bearing steel 1.3520(EN), as a set of properties reflecting the quality of the profile geometry, surface defects, macro and microstructure and mechanical properties was considered. The qualitative evaluation of the achieved quality level, the calculation of the probability of occurrence of defects was made. The methodology of technology management on the basis of statistical relations of the studied quality indicators with parameters of industrial technologies in steelmaking and rolling shops was established.

Tracer Injection Simulations and RTD Analysis for the Flow in 3-Strands Steelmaking Tundish

Steel cleanliness in the continuous casting process can be improved by the enhancement of inclusion floatation via the flow control in tundish.The aim of this study is to define potential steel flow improvements in the 3-strands tundish of BSI (Bangkok Steel Industry) steelmaking shop. The numerical models of tundish without and with flow modifiers are simulated using the commercial computational fluid dynamics (CFD) software, ANSYS Fluent Workbench 14.0. The simulations of tracer injection using species transport model were performed. Flow characteristics were analyzed by RTD (residence time distribution) curves and the volumes fraction of three types of flow conditions. The results from this reseach shows how the current design of the flow modifiers improves some flow characteristics.

The Gboko Limestone, Yandev, Benue State, Nigeria: Geology, Geochemistry and Industrial Potentials

The Cretaceous shallow marine Gboko limestone, Yandev, Nigeria is a component of the sedimentary fill of the 800 km NE-SW trending Benue Trough, Nigeria. The limestone is made up of thin bedded to massive limestone beds interspersed with laminated grey shale having foraminifera as the dominant fossil. The limestone has both mud supported and grain supported texture, and micrites constitute about 75% of the limestone. Bulk chemical composition analysis of the limestone reveals average CaCO3 of 92.41% and a range of 77.50% - 99.00%. Mineralogical impurities include quartz, dolomite, pyrrhotite, fluorapatite etc. Trace elements concentration analysis was carried out using Energy Dispersive X-ray (EDXRF) spectrophotometry and showed the following trace elements: Mn (841.3 ppm), Sr (444.6 ppm), Fe (470 ppm), Zn (114.6 ppm) and Pb (116.4 ppm). Calcining the limestone in a laboratory muffle furnace at 1050°C for 90 minutes produced a compact, soft burnt porous and reactive lime that does not crumble into fines. The lime so produced neither meets the requirements of the Steel Making Shop (SMS) of the Ajaokuta Steel Plant nor could it be used in the growing sugar refining industry in Nigeria. It can however be used in the food and the food by-products industry, environmental, agricultural and petroleum industries etc. The raw stone remains a major source of raw materials for cement manufacture for the ever expanding building industry.

Assessment of dust exposure in a steel plant in the eastern coast of peninsular Malaysia.

Steel manufacturing produces dust, fumes, and pollutant gases that may give adverse health effects to the respiratory function of workers. Improper occupational hygiene practice in the workplace will affect both workers wellbeing and productivity. To assess the level of particulate matter [(PM2.5, PM10, and Total Particulate Matter (TPM)], and trace metal dust concentrations in different sections of a steel plant and compare with the occupational exposure values. The work environmental parameters of the particulate matters were evaluated using Indoor Air Quality, while metal dust concentrations were measured using portable personal air sampler. A total of 184 personal samples were randomly collected from workers in three major sections; steel making plant, direct reduced plant, and support group. Trace metal dust concentrations were subjected to wet mineral acid mixture digestion and analysed by atomic absorption spectrophotometer (AAS). The overall average PM2.5 concentration observed was varied according to the section: steel making plant was 0.18 mg/m3, direct reduced iron plant was 0.05 mg/m3, and support plant was 0.05 mg/m3. Average PM 10 concentration in steel making shop (SMS) plant, direct reduced (DR) plant, and support plant were 0.70 mg/m3, 0.84 mg/m3, and 0.58 mg/m3, respectively. The average TWA8 of trace metal dusts (cobalt and chromium) in all the sections exceeded 1 to 3 times the ACGIH prescribed values, OSHA PELs, NIOSH RELs as well as USECHH OSHA, whereas TWA8 concentration of nickel for each section did not exceed the occupational exposure values. The average PM2.5, PM10 and TPM did not exceed the prescribed values, while average trace metal dust concentration TWA8 for cobalt and chromium in all plants exceeded occupational exposure prescribed values. However, the nickel found did not exceed the prescribed values in all the plants except for NIOSH RELs.

Economic efficiency of automated control system on the example of a vacuum arc furnace in the steelmaking shop JSC «Metallurgical Plant «Electrostal»

In order to explore the possibility to reduce energy costs and waste , as well to increasing the quality of melted ingots , the vacuum arc furnace DVS-3.2-G1 in the steelmaking shop of JSC «Metallurgical Plant «Electrostal» has been modernized. The calculations of the cost of waste, electricity and wages, as well as of cost price including depreciation before and after the modernization of management system are presented. The diagram of financial flow, calculations of net present value over the years, as well as after the first and second iteration are presented. Data of the economic efficiency of the vacuum arc furnace automatization from 2014 to 2016 are presented. The article presents data of economic efficiency, estimates the cost of developing and implementing of the automated process control system. Established is the economic feasibility of the introduction of automatic process control on other vacuum arc furnaces in JSC «Metallurgical Plant «Electrostal».

Modeling of steelmaking process with effective machine learning techniques

Monitoring and control of the output yield of steel in a steelmaking shop plays a critical role in steel industry. The yield of steel determines how much percentage of hot metal, scrap, and iron ore are being converted into steel ingots. It represents the operational efficiency of the steelmaking shop and is considered as an important performance measure for producing a specific quantity of steel. Due to complexity of the steelmaking process and nonlinear relationship between the process parameters, modeling the input–output process parameters and accurately predicting the output yield in the steelmaking shop is very difficult and has been a major research issue. Statistical models and artificial neural networks (ANN) have been extensively studied by researchers and practitioners to model a variety of complex processes. In the present study, we consider random forests (RF), ANN, dynamic evolving neuro-fuzzy inference system (DENFIS) and support vector regression (SVR) as competitive learning tools to verify the suitability of applications of these approaches and investigate their comparative predictive ability. In the present investigation, 0.00001 of MSE is set as a goal of learning during modeling. Based on real-life data, the computational results depict that the training and testing MSE values of SVR and DENFIS are close to 0.00001 indicating that they have higher prediction ability than ANN and RF. Also, mean absolute percentage prediction errors of the proposed models confirm that the predicted yield based on each method is in good agreement with the testing datasets. Overall, SVR performs best and DENFIS the next best followed by ANN and RF methods respectively. The results suggest that the prediction precision given by SVR can meet the requirement for the actual production of steel.

Preparation of Samples of Liquid Metal for Analysis

A new unit has been designed to cool metal samples to the required temperature. Compressed gas is used as the cooling medium in the unit and is induced to vibrate by an acoustic radiator. Use of the unit in the electric steelmaking shop at the Severskii Pipe Plant has made it possible to obtain metal samples which are evenly cooled over their entire surface. The amount of compressed air used in the cooling operation is reduced appreciably.

Diagnostic Functions of a System for Continuous Monitoring of the Technical Condition of the Transformers of Arc Steelmaking Furnaces

This article describes the specifications of the FTOHBR-150200/35 transformers that are made by the company TAMINI and were installed on 180-ton arc steelmaking furnaces (DSP-180 furnaces) in the electric steelmaking shop at the Magnitogorsk Metallurgical Combine. It also gives the specifications of the ETTsNKV – 40000/110 transformers that are made by the Elektrozavod company and were installed on ladle-furnace units in the same shop. Features of the loading regimes of the furnace transformers are discussed and are taken into account in substantiating the diagnostic functions of a system to continuously monitor transformers’ technical condition. The requirements that were established have been used to design systems for on-line monitoring of the DSP-180 transformers.

Reoxidation of Al-Killed Molten Steel by Fe2O3and Cr2O3in the Magnesia-Chromite Refractory

In the present work, the reoxidation of Al-killed molten steel from the magnesia-chromite refractory was investigated. Firstly, the composition and the phases of magnesia-chromite bricks from three different steelmaking shops were analyzed. Secondly, the magnesia-chromite bricks were immersed in Al-killed molten steel for a determined time to observe the reaction mechanism. Finally, the reoxidation of Al-killed molten steel by the magnesia-chromite bricks was evaluated based on a comparison with the pure magnesia crucibles. The XRF showed the Fe2O3 content of the magnesia-chromite bricks is about 6 mass%, and the Cr2O3 content is in a range of 13–19 mass%. The XRD pattern showed the phases in the bricks are mainly MgO and (Mg,Fe)(Cr,Al,Fe)2O4. The fracture surface of magnesia-chromite bricks after immersion in Al-killed molten steel indicated that there exists a reacted layer, and the reacted layer formed after immersion in the low Cr steel is more obvious than that formed after immersion in the high Cr steel. The SEM–EDS of magnesia-chromite bricks showed that (Mg,Fe)(Cr,Al,Fe)2O4 in the reacted layer decreased after immersion in Al-killed molten steel, especially in the low Cr molten steel. Compared with steel melted in pure magnesia crucibles, the total oxygen of steel melt in magnesia-chromite crucibles showed a lower decreasing rate, and the rate of Cr increase and Al loss were much larger, especially in the low Cr molten steel.

Steel research int. 2/2013

Cover Photo: The Cover shows single Snorkel Refining Furnace at No. 2 Steelmaking Shop in TISCO. More details can be found in the manuscript Jiang et.al.

Determination of Physical and Chemical Properties of Electric Arc Furnace Dusts for the Purposes of Their Utilization

AbstractElectric arc furnace dusts are among the most environment polluting wastes. Numerous utilization technologies have been developed for dusts containing up to 4% of Zn and more than 20% of Zn. However, the remaining part of steelmaking dusts are the most problematic ones, as they are mostly dumped generating costs and posing serious environmental threats. This paper provides an analysis of the potential utilization options for dusts containing ca. 10% of zinc generated in a single electric steelmaking shop. Physical and chemical properties of dusts have been determined and examined, and furthermore, results of the studies on the EAFD utilization in production of cement clinker and industrial glass have been discussed. It has been found that a particularly beneficial feature of the production technology proposed is that the iron content exceeds 30%. The influence of the dusts used on the functional properties of the products obtained has been established as well as the environmental impact of the processes and products in question and the dust mass possible to be utilized in the production technology proposed have been determined.

Mixture Calculation of Chromium Ore Smelting Reduction Process in a Converter

The mixture calculation of producing stainless steel crude melts by chromium ore smelting reduction in a 150 t converter is carried out by use of the empirical data and the calculation method of refining plain carbon steel in a converter, according to the blowing conditions of 185 t smelting reduction converter of No.4 steelmaking shop in Chiba Works of JFE Steel. The calculation results show that the required total consumption of chrome ore, coke and limestone in the smelting reduction process is 224.942 kg, 154.9 kg and 99.223 kg, respectively, under the conditions of this calculation. The total amount of slag includes the amounts of hot metal elements oxidation into slag, lining erosion into slag and chromium ore, coke and adding flux into the slag, which is calculated respectively according to the basic raw data and the set values of process parameters. The slag component is confirmed, namely, the actual basicity w(CaO)/w(SiO2)=2.6, the percentage of CaF2 in slag is 3~4 wt%, and the calculated w(MgO)/w(Al2O3)=0.7. In the actual production, the addition of chrome ore, coke and flux is increased by 3%, 2% and 1%, respectively.

Heat Balance Calculation of Chromium Ore Smelting Reduction Process in a Converter

The heat balance calculation of producing stainless steel crude melts by chromium ore smelting reduction in a 150 t converter is carried out by use of the empirical data and the calculation method of refining plain carbon steel in a converter, according to the blowing conditions of 185 t smelting reduction converter of No.4 steelmaking shop in Chiba Works of JFE Steel. In the heat balance calculation, the heat consumption is calculated according to the actual reduction process in the converter and the thermal efficiency and the coefficient of thermal energy of smelting reduction converter are calculated. The calculation results show that the thermal efficiency η is 60.143% and the coefficient of thermal energy KT is 71.743%. The calculated relative error of heat balance is 0.019%. Heat balance calculation is an important part of the converter smelting process calculation, and it is extremely significant in the pursuit of the converter production of high quality and low energy consumption.

Material Balance Calculation of Chromium Ore Smelting Reduction and Direct Alloying Process in a Converter

The production process of stainless steel by chromium ore smelting reduction and direct alloying is an important and advanced way to raise the productivity of stainless steel, decrease the production cost, save electric energy and improve the economic profit. The material balance calculation of producing stainless steel crude melts by chromium ore smelting reduction in a 150 t converter is carried out by use of the empirical data and the calculation method of refining plain carbon steel in a converter, according to the blowing conditions of 185 t smelting reduction converter of No.4 steelmaking shop in Chiba Works of JFE Steel. It includes the actual oxygen consumption, furnace gas composition and occurrence amount, mass calculation of stainless steel crude melts and preparation of total material balance table. The absolute error of material balance is -2.859 kg and the relative error is -0.169%. The error is very small, so the material balance calculation can provide certain quantitative basis for determining reasonable design parameters and increasing smelting technology economic indicators.

Study and Design of Chromium Ore Smelting Reduction Process for Producing Stainless Steel in a Converter

This paper describes the concept of the construction of steelmaking shop, which is carried out as part of a modernization plan aimed at creating a 21st century environmental-friendly iron and steel works, designs the smelting reduction process of producing stainless steel crude melts in a 150 t converter and presents an outline of the equipment specifications and the conditions of operation, according to the blowing conditions of 185 t smelting reduction converter of No.4 steelmaking shop in Chiba Works of JFE Steel. In the future, a rational production system will be constructed by flexible selection of raw materials in response to changing stainless steel raw material prices and further improvement in productivity and quality, making the maximum use of functions of the equipment.

Modernization of the secondary cooling system of a continuous slab caster at ural steel

A new water-air system for the secondary cooling of slabs on a continuous caster in the electric steelmaking shop at Ural Steel has been developed and introduced on the basis of an analysis of the operation of the caster as a whole. New schemes were devised for the locations of the manifolds and nozzles, the water distribution system, mixers, and nozzles were redesigned, and new secondary cooling regimes were instituted. Introduction of the new system for the secondary water-air cooling of slabs has made it possible to expand the production of special steels and improve the quality of the slabs’ surface and macrostructure.

Analyzing the performance of the secondary water-cooling system of a single-strand continuous slab caster in the electric steelmaking shop at ural steel

The design of the secondary-cooling system of a continuous slab caster in the electric steelmaking shop at Ural Steel is analyzed. Defects in the slabs are studied and the effect of secondary cooling on the surface defects and macrostructure of the slabs is determined. Thermal calculations are performed of the slab crystallization process, and it is found that the existing design of the secondary-cooling system makes it impossible to use the caster to cast high-strength tube steels or ship plate. Technical recommendations are made for modernizing the system.

Process Calculation of Producing Stainless Steel Crude Melts by the Chromium Ore Smelting Reduction in a Converter

The process calculation of producing stainless steel crude melts by smelting reduction in a 150 t converter is carried out for the first time by use of the empirical data and calculation method of refining plain carbon steel in a converter, according to the blowing conditions of 185 t smelting reduction converter of No.4 steelmaking shop in Chiba Works of JFE Steel. Using the self-programming procedure for the processing calculation, the proper coke quantity and a complete set of calculation data for the process of smelting reduction in a converter are obtained, including the batch calculation, the material balance and heat balance calculations. The calculation results show that the increase of PCR can decrease the quantity of coke and actual oxygen consumption considerably, and improve the thermal efficiency of smelting reduction converter. For producing 18 wt% Cr stainless steel crude melts, comparing with the process of electric arc furnace, the process of smelting reduction in a converter can reduce the production cost greatly. The use of the recycled metal containing chromium can shorten blowing time and improve the yield of chromium.

MODELAGEM MATEMÁTICA DO PROCESSO DE SECAGEM E AQUECIMENTO DE PANELAS DE AÇO

This paper presents a methodology to quantify the stored heat in a steel ladle in a Steelmaking Shop in order to calculate the heat input required by the drying and heating process by using a natural gas heater. The current situation is mathematically modeled in order to obtain the combustion energy balance. Through finite element modeling in transient state it is possible to obtain the thermal profile, measure process losses and propose adjustments to the drying and heating curves