Papers by Keyword: Steelmaking

Abstract: With an aim to utilize the local-based waste materials, this research investigated the production of mill scale - biomass pellet (MBP) as an alternative charged material for EAF steelmaking. Rubber tree bark (RTB) is one of the major biomasses in Thailand, consisting of carbon and hydrogen as the main compositions. The carbon derived from RTB was mixed with coal into five different ratios. Pure coal and RTB were employed for comparison. Seven carbonaceous samples were blended with mill scale at a C/O molar ratio of 1:1 to produce MBP, namely Coal, blend#1 – blend#5 and RTB. The reduction of MBP was investigated in a horizontal tube furnace under argon atmosphere at 1550°C for 15 and 30 minutes. The obtained products were iron droplets and residual black powder of unreacted oxides. Quantities of reduced iron from the MBP of blend#1 – blend#5 was about 58 – 61 wt% after 30 minutes, while it was 62 wt% and 57 wt% for coal and RTB, respectively. Degree of metallization (DOM) for blend#1 – blend#5 was between 78.1 – 81.7%, while it was 82.7% and 83.3% for coal and RTB. This research offers the possible method to utilize mill scale and RTB biomass toward circular economy.

Abstract: A 300-metric ton converter in a steel plant in China was studied. The influence of factors such as slag composition and temperature in the smelting process on the dephosphorization effect was statistically analyzed. The dephosphorization ability of slag increased firstly and then decreased with the increase of temperature, basicity and FeO content. Low-temperature, high-basicity and high-oxidizing slag are thermodynamically beneficial to promote the dephosphorization reaction, but the basicity is higher than 4.0, and the temperature is higher than 1640 °C are not conducive to the slag to obtain better fluidity. At the same time, too high FeO content will increase the activity coefficient of P₂O₅, thereby increasing its activity, which is not conducive to the progress of the dephosphorization reaction. As the end point content of carbon decreases, the oxygen content increases and the phosphorus content decreases. A very low carbon content is not conducive to metal yield and temperature control.

Abstract: An investigation on the reduction of iron ore with carbonaceous material as a reductant was carried out at 1550°C. Iron ore was mixed with biochar from palm shell and coke as a reference at C/O molar ratio of 1.0. Characterisation of raw materials was performed using X-ray Fluorescence (XRF), Brunauer–Emmett–Teller (BET), Fourier Transmittance Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD) and Scanning Electron Microscope (SEM-EDX). The samples after reduction were characterised to study the phase transformation and structural properties. The XRD results revealed the iron ore contained hematite as its main composition. After reduction at high temperature, the hematite has been successfully reduced to metallic iron using biochar as a reductant. It was found that the reaction proceeded in a stepwise reduction of iron oxide. The SEM micrographs proved the formation of metallic iron in the sample after reduction at 1550°C. Through characterisation, the biochar from palm shell has physical properties suitable to be an alternative carbon reductant to replace coke.

Abstract: Steelmaking is accompanied with releasing a large quantity of solid particle in the form of dust. Electric arc furnace dust (EAFD) is known to have high pH number and traces of heavy metals. The objective of this work was to find a suitable procedure for converting the dust waste into inert and useful byproducts using thermodynamic calculations and experimental investigation. The physical, chemical and mineralogical characteristics of initial EAFD were analyzed using different techniques, such as: X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), grain size analysis and metallography. The pH measurement procedure was carried out in accordance with the standard test method for pH of soils “ASTM 4972-95a”. The results of XRD, SEM and EDS analysis were consistent and showed that Fe₂O₃, CaO, Al₂O₃, SiO₂, MgO, ZnO and traces of other oxides are in the main composition of the EAFD batches with different relative amounts. Furthermore, the particle size measurements revealed that the EAFD particles are in the 0.1 to 394 μm size range. The pH number was ranging between 11.15 and 12.21 for all measurements. The experimental results were used as input data for thermodynamic calculations and accordingly SiO₂ and Al₂O₃ were among the candidates for making ceramic materials through forming glass regions that surround and encapsulate the iron oxide particles. SiO₂ modified samples exhibited better apparent structural properties than other compositions. Whereas Al₂O₃-modified samples showed variation in the product color. Thus, it is concluded from this work that a mixture of EAFD can be modified by 5-20 wt.% of SiO₂ and then fired at 1100°C to make inert ceramic materials with reasonable mechanical properties.

Abstract: The process of LF Refining is introduced in this paper. Because the LF ladle furnace has the advantages are widely used and developed in many companies. The argon is blown into the ladle, so the purpose of refining is achieved. The argon stirring can accelerate the chemical reaction between slag and steel. In the circulation process, large inclusion and deoxidation product in the lower region transfer into the slag. The material transfer between steel and slag can be accelerated. At the same time, argon stirring can make molten steel composition and temperature uniformity. Thus, the ladle of blowing argon can be roughly divided into three important flow region has been introduced. Two-phase region, the top horizontal flow zone and recirculation zone exists in the ladle.

Abstract: At present, China's IF steel production has get a certain scale. But IF steel production is still in the primary stage of development. Therefore, the process control of inclusions in IF steel have become a pressing matter of the moment. This has important theoretical value and practical significance for further development of IF steel production in China. According to the size, the inclusions can be divided into super micro inclusions, micro inclusions and micro inclusions in the steel. According to the deformation capacity, inclusions can be divided into plastic inclusions, semi plastic inclusion and brittle inclusion.

Abstract: A thermo-mechanical finite element model was developed by using FEA commercial software, in order to estimate thermal stress levels in a refractory lined steelmaking ladle shell during its first preheating stage. The model considers two refractory linings: an inner working lining and a permanent one besides the external ladle shell. In this way, stresses on both refractory lining and metallic shell due to restricted lining thermal expansion were simulated. Stress-strain curves of refractory lining materials at different temperatures were obtained through lab tests and then used for model optimization. Additionally, creep behavior in the steel shell under different tensile stresses and temperatures was also estimated taking into account previously obtained results from laboratory tests. In plant strain and temperature measurements were done by instrumenting the lower part of the ladle sidewall shell with high temperature strain gauges and thermocouples. Predicted stress evolution showed good agreement with results obtained from in plant measurements.

Abstract: The research status of numerical simulation on LF furnace refining ladle is introduced in this paper.Since 1970, the research on the gas-liquid two-phase region has begun.Szekely began to be simulated by mathematical model and physical experiment method of flow phenomena in ladle in early 1975. It is the first time that the numerical model is introduced to study the refining process of steel. The plume model is presented by Xiao Zeqiang in 1980, then the numerical simulation began to develop rapidly.

Abstract: The research status of physical simulation on LF furnace refining ladle is introduced in this paper.Since 1970, the research on the gas-liquid two-phase region has begun. The ladle of blowing argon can be roughly divided into three important flow region has been introduced. Two-phase region, the top horizontal flow zone and recirculation zone exists in the ladle.The establishment of physical model should include similarity principle and flow field measurement technique

Abstract: The process of LF Refining is introduced in this paper.The LF method is a ladle without vacuum equipment can arc refining method.Because the LF ladle furnace has the advantages of simple equipment, low investment cost, flexible operation and excellent refined effect, are widely used and developed in many countries.The argon is blown from the bottom of the ladle, and molten steel is heated by the graphite electrode, so the purpose of refiningis achieved. The argon stirring can accelerate the chemical reaction between slag and steel.LF refining function includes reductive atmosphere, submerged arc heating, argon stirring and white slag refining.