Ironmaking Industry Research Articles

Distribution of Zn, Pb, K, and Cl in Blast Furnace Lining

The furnace campaign of a blast furnace represents an important factor for the iron-making industry due to the fact that maintenance such as relining is not only costly but also time consuming. The furnace campaign is largely determined by the functionality of the lining, which is influenced by wear mechanisms and the damaging behavior of certain elements. To these unwanted elements that may attack the lining belong, for example, Zinc (Zn), Lead (Pb), Potassium (K), and Chlorine (Cl). In this paper, the distribution of Zn, Pb, K, and Cl within the lining of a blast furnace at the end of its furnace campaign is investigated and discussed. The results demonstrate that the content of some elements (Zn, Cl, Pb) in the lining and also their penetration depth significantly varies over the blast furnace height. For Zn and Pb, the highest contents (43 g Zn kg−1 and 0.14 g Pb kg−1) are observed in the inner lining stones (adjacent to the hot metal), whereas for Cl, a contrary distribution pattern is observed. The highest contents are detected in the outer stones of the lining at the top of the blast furnace.

Comprehensive Numerical Modeling of the Blast Furnace Ironmaking Process

Blast furnaces are counter-current chemical reactors, widely utilized in the ironmaking industry. Hot reduction gases injected from lower regions of the furnace ascend, reacting with the descending burden. Through this reaction process, iron ore is reduced into liquid iron that is tapped from the furnace hearth. Due to the extremely harsh environment inside the blast furnace, it is difficult to measure or observe internal phenomena during operation. Through the collaboration between steel companies and the Center for Innovation through Visualization and Simulation, multiple computational fluid dynamics (CFD) models have been developed to simulate the complex multiphase reacting flow in the three regions of the furnace, the shaft, the raceway, and the hearth. The models have been used effectively to troubleshoot and optimize blast furnace operations. In addition, the CFD models have been integrated with virtual reality. An interactive virtual blast furnace has been developed for training purpose. This paper summarizes the developments and applications of blast furnace CFD models and the virtual blast furnace.

Capturing CO2 Emissions in the Iron Industries using a Magnetite–Iron Mixture

AbstractWe examined a mixture of magnetite (Fe3O4) and iron (Fe) as a possible CO2 sorbent easily applicable for any ironmaking industries. The mixture reacts with CO2 to form siderite (FeCO3). Our experimental results illustrate a capture capacity of 7.98 mmol for the reactant mixture at 200 °C and 10 bar CO2 pressure in 3 h. The results also show that the kinetics of the carbonation reaction vastly depend on the applied temperature and CO2 pressure. The magnetite was completely regenerated by heating siderite at 350 °C under air flow. The proposed set of reactions can be integrated at any ironmaking sites and can provide a potential solution for CO2 capture in the future.

Quantitative X-ray Diffraction (QXRD) analysis for revealing thermal transformations of red mud

Red mud is a worldwide environmental problem, and many authorities are trying to find an economic solution for its beneficial application or/and safe disposal. Ceramic production is one of the potential waste-to-resource strategies for using red mud as a raw material. Before implementing such a strategy, an unambiguous understanding of the reaction behavior of red mud under thermal conditions is essential. In this study, the phase compositions and transformation processes were revealed for the Pingguo red mud (PRM) heat-treated at different sintering temperatures. Hematite, perovskite, andradite, cancrinite, kaolinite, diaspore, gibbsite and calcite phases were observed in the samples. However, unlike those red mud samples from the other regions, no TiO2 (rutile or anatase) or quartz were observed. Titanium was found to exist mainly in perovskite and andradite while the iron mainly existed in hematite and andradite. A new silico-ferrite of calcium and aluminum (SFCA) phase was found in samples treated at temperatures above 1100°C, and two possible formation pathways for SFCA were suggested. This is the first SFCA phase to be reported in thermally treated red mud, and this finding may turn PRM waste into a material resource for the iron-making industry. Titanium was found to be enriched in the perovskite phase after 1200°C thermal treatment, and this observation indicated a potential strategy for the recovery of titanium from PRM. In addition to noting these various resource recovery opportunities, this is also the first study to quantitatively summarize the reaction details of PRM phase transformations at various temperatures.

Utilization of Low Grade Iron Ore (FeOOH) and Biomass Through Integrated Pyrolysis-tar Decomposition (CVI process) in Ironmaking Industry: Exergy Analysis and its Application

Utilization of Low Grade Iron Ore (FeOOH) and Biomass Through Integrated Pyrolysis-tar Decomposition (CVI process) in Ironmaking Industry: Exergy Analysis and its Application

Optimum temperatures for carbon deposition during integrated coal pyrolysis–tar decomposition over low-grade iron ore for ironmaking applications

Deposited carbon within low-grade iron ore which was produced using integrated coal pyrolysis and tar decomposition showed high reactivity as a reducing agent. However, pyrolysis and tar decomposition were both highly sensitive to temperature and exhibited contrasting behaviors during carbon deposition. In these experiments, the optimum temperatures for pyrolysis and tar decomposition were determined to obtain maximum carbon deposition. High-temperature pyrolysis generated large amounts of volatile matter (tar and gases), which caused high tar decomposition and produced larger deposited carbon and gases. The deposited carbon was major product of tar decomposition at lower temperatures (400–600°C), whereas mainly gases were produced at higher temperatures (700–800°C), because of carbon gasification. The highest amount of deposited carbon was obtained at a pyrolysis temperature of 800°C and a tar decomposition of 600°C. Hamersley ore gave higher amounts of deposited carbon than Robe-river ore because of its large pore size of less than 4nm, which was suitable for carbon deposition. The pore size distribution was a more important factor than the surface area. Based on these results, the proposed system could achieve maximum carbon deposition and solve problems related to reducing agents, tar materials, and the use of expensive materials in the ironmaking industry.

Carbon Deposition Using Various Solid Fuels for Ironmaking Applications

In this paper, we describe an innovative process involving iron reduction through chemical vapor deposition for applications in the ironmaking industry. In our experiment, we produced tar vapors from pyrolysis of various solid fuels, including high-grade bituminous coal (HGC), low-grade lignite coal (LGC), and biomass palm kernel shell (PKS), and decomposed these vapors into gases, carbon, and light hydrocarbon. Carbon was deposited within the pores of pisolite ore (low-grade ore), which became porous during the dehydration process at 450 °C. We determined that the amount of tar produced during pyrolysis strongly affected carbon deposition, and HGC produced the highest carbon deposition because of its large tar product. In addition to tar amount, surface area and pore volume also played important roles in this process. PKS had the highest ratio of deposited carbon because it produced the smallest quantities of reacted tar and, consequently, the largest numbers of vacant pores. The amount of carbon deposition decreased at higher temperatures because tar was easily converted to a gaseous phase. The deposited carbon within iron ore showed potential as a reducing agent because it was highly reactive and reduced at lower temperatures. Carbon deposited within iron pores dramatically reduced the contact distance between the iron ore and carbon. Thus, these results show that our proposed methodology could have important applications as an alternative low-energy approach for producing metallic iron using low-grade materials.

Mineralogy, geochemistry and origin of Mn in the high-Mn iron ores, Bahariya Oasis, Egypt

Although Mn is one of the major impurities in the economic iron ores from the Bahariya Oasis, information on its modes of occurrence and origin is lacking in previous studies. High-Mn iron ores from El Gedida and Ghorabi–Nasser iron mines were subjected to detailed mineralogical, geochemical, and petrographic investigations using X-ray diffraction (XRD), infrared absorption spectrometry (IR), Raman spectroscopy, X-ray fluorescence (XRF), scanning electron microscopy (SEM), and electron probe microanalyzer (EPMA) to clarify the modes of occurrence of Mn in these deposits and its origin. The results showed that the MnO2 contents range between 0.03 and 13.9wt.%. Three mineralogical types have been identified for the Mn in the high-Mn iron ores, including: (1) inclusions within the hematite and goethite and/or Mn accumulated on their active surfaces, (2) coarse-grained and crystalline pyrolusite, and (3) fine-grained cement-like Mn oxide and hydroxide minerals (bixbyite, cryptomelane, aurorite, romanechite, manjiroite, and pyrochroite) between the Fe-bearing minerals. The Mn carbonate mineral (rhodochrosite) was detected only in the Ghorabi–Nasser high-Mn iron ores. Since IR patterns of low-Mn and high-Mn samples are almost the same, a combination of XRD analysis using non-filtered Fe-Kα radiations and Raman spectroscopy could be the best way to identify and distinguish between different Mn minerals.Assuming that both Fe and Mn were derived from the same source, the occurrence of high-Mn iron ores at the base of the stratigraphic section of the deposits overlain by the low-Mn iron ores indicated a supergene origin of the studied ores by descending solutions. The predominance of Mn oxide and hydroxide minerals in botryoidal shapes supports this interpretation. The small grain size of Mn-bearing minerals as well as the features of microbial fossils such as spherical, elliptical, and filamentous shapes of the Fe-bearing minerals suggested a microbial origin of studied iron ores.Variations in the distribution and mineralogy types of Mn in the iron ores of the Bahariya Oasis demanded detailed mineralogical and petrographic characterizations of the deposits before the beneficiation of high-Mn iron ores from the Bahariya Oasis as feedstock for the ironmaking industries in Egypt by magnetizing reduction. High Mn contents, especially in the Ghorabi–Nasser iron ore and occurrence of Mn as inclusions and/or accumulated on the surface of the Fe-bearing minerals would suggest a possible utilization of the high-Mn iron ores to produce ferromanganese alloys.

Modeling and Scheduling Optimization for Bulk Ore Blending Process

A new scheduling model for the bulk ore blending process in iron-making industry is presented, by converting the process into an assembly flow shop scheduling problem with sequence-depended setup time and limited intermediate buffer, and it facilitates the scheduling optimization for this process. To find out the optimal solution of the scheduling problem, an improved genetic algorithm hybridized with problem knowledge-based heuristics is also proposed, which provides high-quality initial solutions and fast searching speed. The efficiency of the algorithm is verified by the computational experiments.

A Review of the Relationship between Viscosity and the Structure of Calcium‐Silicate‐Based Slags in Ironmaking

AbstractThis review focuses on elucidating the viscosity of ironmaking slags and the effect of various components in the multi‐component calcium‐silicate‐based slag system on the viscosity. Using various widely used spectroscopic techniques including Fourier transform infrared (FTIR), Raman, X‐ray photoelectron spectroscopy (XPS), and nuclear magnetic resonance (NMR), the viscous behavior and the slag structure of this system were correlated. In particular, the review begins with an introduction to the viscous behavior of binary silicate systems and an identification of the intricate details of the slag structure. Using the binary system as a basis, the compounded effect of typical ironmaking slag components such as Al2O3, MgO, alkali oxides, and TiO2 on the viscosity is introduced through expansion to a quinary slag system. Using a combination of the aforementioned spectroscopic methods, the meticulous details of the slag structure were ascertained, and the depolymerization or polymerization mechanisms of the silicate and alumino‐silicate structures were subsequently identified. This review also compares well‐known viscosity prediction models with experimentally measured values and identifies potential fields of research in the ironmaking industry associated with slag viscosities.

Analysis of volatile organic compounds in polyurethane coatings based on Eucalyptus sp. bio-oil pitch using comprehensive two-dimensional gas chromatography (GC × GC)

The development of biomass products seems to be a near-term alternative to fossil derivatives, which aim to mitigate climate changes. It is therefore necessary to investigate whether biomass technologies are really safe and without environmental impact. This work presents a characterization of the volatiles that are released from biopitch and its polyurethane films. Biopitch was obtained via the distillation of Eucalyptus sp. bio-oil; it was recovered by the condensed smoke that was obtained during slow pyrolylis, which is a process that is used to produce charcoal for the iron-making industry in Brazil. Biopitch and castor oil mixtures, in different proportions, were used as polyols in the polyurethane synthesis. The reactions were carried out when the polyol mixtures were stirred together with polymeric MDI (4,4′ methylene diphenyl diisocyanate) NCO/OH = 1.1 and dibutyltin dilaurate as a catalyst. The films were analyzed by comprehensive two-dimensional gas chromatography and time-of-flight mass spectrometry (GC × GC/TOFMS). The best experimental conditions that permit the identification of 104 volatile organic compounds were determined. Although the analysis was not quantitative, it was possible to conclude that a large content of biopitch led to the release of a large number of different substances. The main compounds that were released are phenolic methoxyl substituted substances with one aromatic ring and a low toxicity. Due to its high resolution and sensitivity, the methodology that was used seems to be adequate for the analysis of other macromolecular fractions (biopitches) and polymeric materials that are derived from bio-oils.

Numerical analysis of isothermal flow in lower part of blast furnace considering effect of cohesive zone

The increasing interest in minimising fuel consumption and reducing environmental problems of the ironmaking industry has led to efforts to optimise the blast furnace process. One of the undeveloped fields generated from the adoption of new operating conditions is the internal phenomenon in the lower part of the furnace following the change of cohesive zone shape. The effective liquid flow in the dripping zone of a blast furnace is important for stable operation with high iron productivity. Study of the liquid flow behaviour in a packed bed needs to investigate the effect of various operational changes in the dripping zone. As a stepping stone toward the comprehensive modelling which includes chemical reaction and its associated heat transfer, isothermal flow for three phases is simulated with the variation of the shape of cohesive zone to see the effect of charging condition.

Economies of scale in global iron-making

In this paper, we investigate the presence of economies of scale in the global iron-making industry for integrated steel plants, iron making being the first stage in the steel-making process. Iron making depends on basic commodities, such as iron ore, coke and various forms of energy, required in the operation of the blast furnace, which can be classified as essential inputs and used in fixed proportions to produce iron. A generalized Leontief cost function is estimated using panel data for 69 integrated plants, such a specification being appropriate for technologies with essential inputs that are used in fixed proportions in production. A significant scale effect is observed due to the existence of fixed costs and a linear dependence of the cost function on production. Under a simple linear cost function, a rough estimate of the breakeven scale of plant, where costs equal revenue, is 4.5 Mt per year. Competitiveness, as measured by the ratio of plant average cost per tonne to best practice cost per tonne, can be shown to be positively related to the scale of production as well as the cost of essential inputs. Therefore, low-cost producers are also often producers with low raw material costs and production levels below the estimated breakeven scale of operation. Labor costs, although significant, are comparatively less important as a driver towards low costs.

Investigation on steelmaking dust recycling and iron oxide red preparing

To investigate the physical and chemical properties of the steelmaking dust, wet sieve separation, XRD, SEM, EDS, and traditional chemical analysis were carried out to obtain the particle size distribution, mineralogy, morphology, and the chemical composition of the dust. The dust with a total Fe content of 64.08wt% has coarse metallic iron, magnetite and hematite grains, while fine clay minerals with a size of <38 μm are mainly iosiderite, calcium silicate, and calcite, which are conglomerated to each other. By following the procedures of wet magnetic separation, acid leaching, and oxidization calcination, magnetic materials were recycled and further prepared as iron oxide red with a productivity of 0.54 ton per unit ton of the dust. Middle iron concentrate with an Fe content of 65.92wt% can be reused as feeding material in the ironmaking industry. Additionally, washed water from acid leaching with an Fe 3+ ion content of less than 5 g·L −1 was recovered as feeding water in the wet magnetic separation procedure.

Evolving Nonlinear Time-Series Models of the Hot Metal Silicon Content in the Blast Furnace

Neural networks are versatile tools for nonlinear modeling, but in time-series modeling of complex industrial processes the choice of relevant inputs and time lags can be a major problem. A novel method for the simultaneous detection of relevant inputs and an appropriate structure of the lower part of the networks has been developed by evolving neural networks by a genetic algorithm, where the approximation error and the number of weights are minimized simultaneously by multiobjective optimization. The networks on the Pareto front are considered possible candidate models that are evaluated on an independent test set. In order to consider the problem of drift in the variables, which may cause parsimonious models to perform poorly on the test set, the weights in the upper layer of the networks are recursively estimated by a Kalman filter. The method is illustrated on a data set from ironmaking industry, where time-series models of the hot metal silicon content in a blast furnace are evolved. The technique is demonstrated to synthesize models with a choice of inputs in agreement with findings presented in the literature and process know-how.

Data-Driven Modelling of Quality and Performance Indices in Sintermaking

In developing data-driven models of complex real-world systems, a common problem is how to select relevant inputs from a large set of measurements. If the observations of the outputs to be predicted by the model are scarce, which may be the case if the outputs are indices determined in toilsome laboratory tests, strict constraints have to be imposed on the number of model parameters. In neural network modelling, this limitation in practice also restricts the number of hidden nodes as well as the number of input variables, since the dimension of the weight vector strongly depends on these. This paper presents a systematic method for data-driven modelling with feedforward layered neural networks, including a method for the selection of input variables. The method is illustrated on a problem from ironmaking industry, where sinter quality indices are predicted on the basis of raw material properties. Furthermore, an inversion technique of the resulting network models is proposed, where an optimization problem is solved to maximize the performance of the sintering operation by manipulating the inputs.

A Method to Forecast the Cohesive Zone of Blast Furnace

The paper describes a method to forecast the cohesive zone of blast furnace whose shape is very important for the quality of iron and the efficiency of iron-making industry. This method builds a model that can be observed during the operation of iron making. The model considers that during the chemical reaction the ore, the coke and the gas abide by two equations: the equation of conservation of mass and the equation of heat conservation. Based on this presumption, by dividing the blast furnace into a series of homocentric circles in the height direction and resolving the equations in every homocentric circle with its own parameters, we can get the relationship between temperature and height of the inner blast furnace. And then, according to the fusibility character of the ore, we can forecast the shape and position of the cohesive zone. Finally, the paper visualizes the cohesive zone of blast furnace and discusses some results achieved through the application of such method to a real blast furnace.

Kinetic Analysis of Iron Carburizaiton during Smelting Reduciton

The most serious issues in the world are a large amount of energy consumption and generation of greenhouse effect gas from iron-making industry. The main factors of energy consumption are reduction of iron ore and carburization of reduced iron at high temperature. If it is possible to accelerate the rates of iron ore smelting reduction and the succeeding carburization at low temperature, the technology will be very valuable to lower energy consumption in the blast furnace. It is well known that phenomena during smelting reduction are very complicated and the mechanism has not yet been clarified. Therefore, in-situ observation of smelting reduction and carburization of iron sample were carried out in our previous work. It was confirmed from the results that iron was carburized without a direct contact with carbonaceous material during smelting reduction. The mechanisms of this unique carburization were discussed and it was obtained a conclusion that formation rate of Fe-C particles caused by smelting reduction mainly determined the overall rate of iron carburization reaction.

Mechanical strength characterization of feed materials used in iron-making industry by Epstein theory

Breakage and selection matrices have been determined for three types of feed materials of the blast furnace (BF): coal, coke and iron ore sinter. These matrices have been used to calculate the evolution of the feed material particle size distribution (PSD) during their grinding, sieving and conveying. Thus, the Epstein theory allows, on one hand, to replace the usual tests of their mechanical strength characterisation and, on the other hand, to predict the PSD in their feeding at the BF.

Zinc recovery from blast furnace flue dust

Blast furnace flue dusts are a mixture of oxides expelled from the top of the blast furnace, whose major components are iron oxides. They also contain zinc, silicon, magnesium and other minor element oxides in lesser amounts. The direct recycling of flue dust is not usually possible since it contains some undesirable elements (zinc and alkaline metals) that can cause operational difficulties in the blast furnace. Furthermore, in some cases the dust contains toxic elements (zinc, cadmium, chromium and arsenic) that make it hazardous and unacceptable for landfill. The fact that it is not possible to recycle this dust directly or to reject it as landfill, makes it necessary to consider the recovery of the valuable elements contained in it and to obtain a non-hazardous residue that can be stored without problem or can be used in agglomeration units in iron-making industries. To reach this objective a sequence of unit operations which consists of leaching, filtration, purification, extraction, stripping and electrolysis processes is required. In this research a blast furnace flue dust which principally consists of iron, with some zinc and other elements oxides has been examined. The preliminary results show that it is possible to leach selectively the valuable elements of the dust by sulphuric acid at low acid concentration and room temperature, giving high recovery using zinc (about 80%). The pregnant solution obtained is subjected to purification and extraction for eliminating its contaminants, and increasing its zinc concentration before electrowinning the zinc.