Furnace Material Research Articles

Thermochemical Corrosion of Furnace Materials in Atmospheres Containing Ammonia

ABSTRACTFurnace components are made from heat‐resistant materials that must withstand the long‐term effects of the atmospheres used during heat treatment. In a nitriding furnace, the atmosphere usually consists of various gaseous media that react not only with the treated parts but also with the furnace equipment. This leads to thermochemical corrosion, even with carefully selected heat‐resistant and stainless steels or nickel‐based alloys. The present research focuses on determining the long‐term effects of ammonia‐containing atmospheres on the metallic furnace materials AISI 309, AISI 314, Alloy 600, and Alloy 601. The materials studied were exposed to numerous nitriding or nitrocarburizing treatments for more than 10 years to investigate the long‐term effects of repeated contact with ammonia‐containing atmospheres. The surface layers of the samples were characterized by several methods to determine the microstructural changes due to nitrogen absorption. A different nitrogen absorption of the metallic furnace materials from the heat treatment atmosphere, depending on the material properties, could be proven by the investigations.

Co-incineration of multiple inorganic solid wastes towards clean disposal: Heat and mass transfer modeling, pollutant generation, and machine learning based proportioning

The co-disposal of solid waste by industrial kilns is presently attracting increasing attention. In this study, we investigate the co-disposal of solid waste, i.e. converter ash (CA), sintered ash (SA), blast furnace bag ash (BA), and municipal solid waste incineration fly ash (MSWIFA), under simulated blast furnace ironmaking conditions. The results show that it is feasible to use blast furnace to treat MSWIFA, but the stability of temperature field should be controlled in the process of co-disposal. With the increase of temperature, the conversion rate of NO decreased to 16.4%, and ZnFe2O4 became the main mineral composition, accounting for 75.53%. Corresponding to the flue gas corrosion condition of solid waste treatment, it is found that the corrosion resistance of the furnace material TH347H is better than 20G. Finally, based on the experimental data, the nested optimization algorithm of machine learning model is established to achieve the reverse output of optimal conditions. Overall, the study provides theoretical support and methodology guidance for the co-disposal of solid waste in blast furnaces in providing support for the further development of co-disposal of solid waste in industrial kilns.

Effect of Thermal Activation on the Mineralogical Structure of Magnesium Slag

Magnesium slag's production process is similar to the Portland cement production process. The raw material used is carbonate-containing dolomite, and is calcined in a rotary kiln at 850-900 oC. Afterwards, ferrosilicon and fluorite raw materials are added to the calcined material, they are ground together and turned into pellets, and then they are reduced at a temperature close to the firing temperature of Portland cement clinker (1250-1350 oC) to obtain crown magnesium and magnesium slag. The reduction time of pellet material in reduction furnaces is 12 hours. During this period, almost all of the magnesium minerals in the mixture material are reduced and taken as crown magnesium metal. The remaining material, described as magnesium production slag (reduction furnace waste), consists of Alite (C3S), Belite (C2S), Celite (C3A) and C4AF minerals contained in Portland cement clinker. Some of the minerals contained in Portland cement clinker in the rotary kiln are formed at temperatures below 1400 °C, which is the clinker firing temperature. The only difference other than the firing temperature is that after the Portland cement clinker is fired in the rotary kiln, the clinker is cooled rapidly, increasing the alite (C3S) crystals formed in its structure and preventing the alite minerals from turning back into belite (C2S) minerals. This study produced magnesium slags at different temperatures (1200-1350 oC) by thermal activation method in an industrial environment. The Bogue and XRD methods calculated the mineral phase amounts of the products produced.

Pilot Tests of Pre-Reduction in Chromium Raw Materials from Donskoy Ore Mining and Processing Plant and Melting of High-Carbon Ferrochromium

Experiments were conducted to pilot the initial reduction in chromium raw materials using the innovative Hoganas technology in a tunnel furnace. To simulate the process, a gas-fired bogie hearth furnace was employed. Technological containers made of silicon carbide crucibles were utilized. Sixteen different combinations of ore and coal mixtures were employed for the initial reduction process. Their total mass was more than 20 tons. Their heat treatment was performed at different temperatures and durations. During the pilot tests, the possibility of achieving chromium metallization was confirmed. Thus, it explains the application of a pre-reduction instead of the sintering or charge heating before the ferrochromium melting, i.e., the power consumption is minimized during the final remelting of the product in DC furnaces. The pilot melting of three batches of the pre-reduced chromium raw materials with various chromium metallization degrees has been tested in the ore-smelting furnace at Zh. Abishev Chemical–Metallurgical Institute (Karaganda). The capacity was 0.2 MVA. To evaluate the technical and economic efficiency of remelting pre-reduced chromium raw materials in commercial DC furnaces, a specific batch of primary ingredients for producing high-carbon ferrochromium, including chromite ore, coke, and quartz flux, was successfully melted in a segregated phase. As a result of the study, it was found that the specific energy consumption for melting high-carbon ferrochromium in the pilot furnace depends on the chromium metallization degree. The researchers tested a range of chromium metallization degrees from 0 to 65% and determined the corresponding specific energy consumption for each degree. Using the data obtained from the study, the researchers were able to assess the melting indexes of high-carbon ferrochromium in a larger 72 MW furnace. They found that by using a pre-reduced product with a chromium metallization degree of 65%, it was possible to reduce the specific energy consumption by half, to around 3.4 MW·h per ton of chromium. Overall, this study highlights the importance of considering the chromium metallization degree when determining the specific energy consumption for melting high-carbon ferrochromium. By optimizing the metallization degree, significant energy savings can be achieved, leading to more efficient and sustainable production processes.

Corrosion testing of prospective chrome refractory materials in borosilicate glass melts

Justification is provided of significant practical relevance of the issue of corrosion and erosion resistance of refractory materials in furnaces with direct electric heating that are used for vitrification of high-level waste. Main promising materials are listed, and an algorithm is given for assessing their resistance to attack of borosilicate glass melts under operating conditions of electric furnaces. Corrosion testing of chrome refractory materials of joint Chinese and Belgian origin has been carried out under static and dynamic conditions in a low-melting borosilicate glass melt and in a borosilicate glass melt containing simulated liquid high-level waste (HLW). A search has been conducted among chrome refractory materials of Chinese and Belgian origin for ones demonstrating the highest glass melt attack resistance with regard to the conditions of HLW solidification. The results of these tests will be considered in the design of removable and small-scale melters when selecting the material for melter lining.

Research on prediction model of iron ore powder sintering foundation characteristics based on FOA-Catboost algorithm

Sintered ore is the most important incoming iron material for blast furnaces in China. The foundation characteristics of sintering are an important basis for the sintering process of iron ore powder and a key indicator for evaluating the quality of iron ore powder. The chemical composition of iron ore powder directly affects the foundation characteristics of sintering. Based on the chemical composition and sintering characteristics of iron ore powder, the article adopts the FOA-Catboost algorithm to establish a prediction model for the foundation characteristics of single iron ore powder and mixed iron ore powder. Among the foundation characteristics prediction indicators of a single type of iron ore powder, the accuracy of assimilation temperature prediction is 95.65 %, the accuracy of fluidity index prediction is 95.23 %, and the accuracy of bonding phase strength prediction is 97.46. Among the foundation characteristics prediction indicators of mixed iron ore powder, the accuracy of assimilation prediction is 95.82 %, the accuracy of fluidity index prediction is 91.66 %, and the accuracy of bonding phase strength prediction is 93.7 %. On the basis of predicting the foundation characteristics of a single type of iron ore powder, the model further predicts the foundation characteristics of mixed iron ore powder, which can reduce the workload of laboratory experiments on the foundation characteristics of iron ore powder and reduce the amount of experiments in the process of finding the optimal proportion of mixed ore. Based on the foundation characteristics model of mixed ore, determine the optimal ratio of sintered ore powder to improve the quality of sintered ore. The establishment of the model has a significant contribution to improving experimental and production efficiency, reducing costs, improving sinter quality, and reducing environmental impact.

Research and modeling of the ecological efficiency of drying refractory and building materials in vertical shaft furnaces

Based on the hypothesis of the dominant effect on the environmental efficiency of drying materials in shaft furnaces of the concentration, median diameter, dispersion, temperature and humidity of dust particles at the outlet of the dryer, a device for thermal aeration separation of dust is proposed. The analysis of mathematical modeling of aerothermodynamic processes in a two-phase medium asbestos dust ‒ gas flow confirmed the conclusions of industrial studies on the influence of aerothermodynamic parameters of direct flow on the temperature and humidity of asbestos dust in the pneumatic dryer. Based on the principle of additive classification, a mathematical model of aeration separation of dust particles directly in the dryer of the shaft furnace is constructed, depending on the parameters of the heat carrier and the proposed device.

Research and Simulation of Environmental Efficiency of Drying Refractory and Construction Materials in Vertical Shaft Furnaces

Research and Simulation of Environmental Efficiency of Drying Refractory and Construction Materials in Vertical Shaft Furnaces

Design of a Thermal Conductivity Measurement Technique for Clay Furnace Materials Using an Arduino-Based Thermocouple Sensor¬

This study aims to design a thermal conductivity measurement system for solid clay furnace materials, measure the thermal conductivity value of a clay furnace using an Arduino-based Thermocouple sensor, and determine the relationship of the thermal conductivity value to variations in clay furnace samples using an Arduino-based thermocouple sensor. The method used in research, design, manufacture and testing of tools. Data collection in this study was to measure the thermal conductivity of 4 samples of clay furnaces based on differences in husks using an Arduino-based Thermocouple sensor. Analysis of research data was carried out using descriptive statistics and inferential statistics, assisted by Microsoft Excel and SPSS programs. In data analysis, univariate, bivariate analysis was performed. The relationship between the value of thermal conductivity to the husk material in each sample has a positive relationship between time and temperature variables, in other words, the more time the temperature increases, the faster the temperature increases. From the results of the study, it can be concluded that the best thermal conductivity is in sample one with a value of 1.5375 J/ (K.m) and the poorest is in sample four with the lowest conductivity value of 0.3125 J/ (K.m).

A Novel Particle Size Detection System Based on RGB-Laser Fusion Segmentation With Feature Dual-Recalibration for Blast Furnace Materials

Particle size detection (PSD) is used to obtain the particle size distribution of materials in the blast furnace charging process, which is significant for optimizing the gas flow distribution and ensuring stable production. However, due to the complex surface texture of the materials and the uneven illumination of the production environment, existing methods have difficulty obtaining the particle size distribution efficiently. This paper proposes an end-to-end PSD system based on image segmentation to obtain the particle size distribution online with high accuracy. First, to further enhance the expression of edge features and reduce the interference of complex textures, an RGB-laser particle segmentation network (RLPNet) is developed to obtain high-precision segmentation images by camera-LiDAR sensor fusion. Moreover, to improve the fusion of RGB and laser features, a feature dual-recalibration (FDR) module was designed and embedded in RLPNet, consisting of independent recalibration and joint recalibration with T-convolution. Finally, to reduce the error caused by missing edge particle pixels, an edge-recognition-based particle size calculation strategy (ERP) is presented. Experimental results demonstrate that the proposed method performs well on the constructed dataset and in industrial applications. With the segmentation accuracy of RLPNet reaching 64.19 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\%$</tex-math></inline-formula> , the similarity between the particle size distribution predicted with ERP and the actual distribution reaches 79.19 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\%$</tex-math></inline-formula> .

Design of The Pyrolysis Furnace for The Alternative Energy

The pyrolysis furnace material needs to be considered because this component affects the performance of the pyrolysis process. This component material is also essential; the selection of components used is AISI 4340 Normalized Steel, where this material contains Nickel, Chrom, and Molybdenum, with the characteristics of the AISI 4340 Normalized Steel material, which is a steel material that has high hardness properties, can accept significant pressures and forces and is not easily deformed. The method used is Finite Element Analysis (FEA); this method uses a mesh size of 5 mm to get more accurate results. Simulation results of the AISI 4340 Steel Normalized rear axle shaft to determine the values of stress, strain, displacement, and safety factor from temperature variations of 150 °C, 175 °C, 200 °C and 225 °C. The highest maximum stress value occurs at a temperature of 225 °C of 7.339 x 108 Nm. The highest maximum strain value occurs at a temperature of 225 °C of 1.892 x 10 3. The highest displacement value occurs at a temperature of 225 °C of 4.891 x 10 1. The safest safety factor value to use is 1.547 at a temperature of 150 °C. The temperature value is directly proportional to the stress and strain values obtained because the more significant the given temperature value, the greater the stress and strain values.

ANCIENT KEDAH IRON SMELTING EXPERIMENT IN PREPARATION FOR OFFERING ARCHAEOLOGICAL TOURISM HERITAGE PACKAGES AT SUNGAI BATU ARCHAEOLOGICAL COMPLEX (SBAC), BUJANG VALLEY, KEDAH, MALAYSIA

In order to obtain primary data related to the iron smelting activities, the experimental process of furnaces, tuyere and air pumps making is carried out. The experiment has conducted since 2013 through the Knowledge Transfer Program (KTP) in Sungai Batu Archaeological Complex (SBAC). Through the experiment, the clay in this complex has been used as a raw material for furnaces and tuyere making while the bellows is made of wood, plywood and fabric. In order to complete the experiment regarding the raw material that use for iron smelting, iron ore was taken through survey activities in the area of Kampung Batu 5, UiTM Merbok and Bukit Tupah while charcoal was used from rubber wood in the rubber plantation near the Sungai Batu Archaeological Complex. After the experiment was conducted, the results recorded were different from the findings of the iron ingot excavation at the iron smelting site which is likely to occur due to the difference in technique and ratio of materials used during smelting activities. Although the results obtained during the experiment are different, the smelting process can be used as the main reference for offering tourism full packages related to the demonstration of iron smelting in this complex to foreign tourists.

A Study on the Fire-Retardant and Sound-Proofing Properties of Stainless Steel EAF Oxidizing Slag Applied to the Cement Panel.

Because of incomplete recycling resource management and technology development, inorganic sludge and slag has been misused in Taiwan. The recycling of inorganic sludge and slag is a pressing crisis. Resource materials with a sustainable use value are misplaced and have a significant impact on society and the environment, which greatly reduces industrial competitiveness. To solve the dilemma of EAF oxidizing slag recycled from the steel-making process, it is important to find solutions to improve the stability of EAF oxidizing slags based on the innovative thinking of the circular economy. We can improve the value of recycling resources and solve the contradiction between economic development and environmental impact. The project team intends to investigate the development and application of reclaiming EAF oxidizing slags blended with fire-retardant materials, which will integrate R&D work from four different aspects. First, a verification mechanism is carried out to establish stainless steel furnace materials. Suppliers must be assisted in conducting quality management for EAF oxidizing slags to ensure the quality of the materials provided. Next, high-value building materials must be developed using slag stabilization technology, and fire-retardant tests must be conducted on the recycled building materials. A comprehensive evaluation and verification of the recycled building materials must be undertaken, and high-value green building materials must be produced with fire-retardant and sound-proofing characteristics. Integration with national standards and regulations can drive the market integration of high-value building materials and the industrial chain. On the other hand, the applicability of existing regulations to facilitate the legal use of EAF oxidizing slags will be explored.

THE TERMAL DEFORMATION OF ISOTROPIC BEAM ELEMENTS OF TECHNOLOGICAL EQUIPMENT IN THE MANUFACTURING OF CARBON-CARBON COMPOSITE MATERIALS IN FURNACES OF DIRECT HEATING

For the isotropic beam elements of the technological equipment (BETE), which are used in the production of carbon-carbon composite materials (CCCM) in direct heating furnaces, the analytical solution of the temperature stress-strain state, taking into account the stiffness of the spring of the current collector, was obtained for the first time in the work. Formulas for calculating the critical diameters of loss of compressive strength are given. Using the example of graphite and molybdenum rods, it was established in the work that the decisive factor of the load-bearing capacity is the loss of stability of the elements under consideration.

3D transient CFD study of iron-coke briquettes pyrolysis and quench processes in an optimised gas heat carrier pyrolyser

Iron coke is an emerging alternative material for iron-making blast furnaces. To massively produce iron coke, the industrial-scale gas heat carrier pyrolyser is a suitable reactor, but the present pyrolysis technology requires further improvements to lower energy consumption and CO2 emission. In this study, a transient 3D CFD model is developed to describe the thermochemical behaviours in the industrial-scale pyrolyser. Meanwhile, a DEM model is used to simulate the packing status evolution of ellipsoidal iron-coke hot briquettes in the pyrolyser chamber, which is input as the simulation conditions in the CFD model. The numerical model is validated against the lab-scale and pilot-scale experimental data. The integrated numerical model is then employed to illustrate heating and quenching processes using the recycled pyrolysis gas as the heat carrier. A new concept that utilises recycled pyrolysis gas to quench the hot briquette after pyrolysis inside the chamber is proposed and examined by the numerical model. In addition, the structure optimisation, i.e., adjustment of the gas inlets' layout, is conducted and numerically examined. The simulation results indicate that the present structure of the pyrolyser has some non-uniform temperature zones, such as the upper bed and near-wall areas where the heat is not effectively transferred to the bed like other zones. 10 h of pyrolysis could effectively pyrolysis iron-coke hot briquettes in the chamber, but for the quenching process, 10 h is not able to fully cool down the briquette bed to room temperature. The design of the upper inlet layout could significantly improve the heating and pyrolysis efficiency. It can shorten 14% heating time in comparison with the original lower inlet layout.

Development of low-loss minimal exposure technique for thallium foil fabrication

Despite its availability as a solid bead or ingot, non-isotopic thallium metal is no longer commercially produced as a foil because of its high toxicity. To conduct fundamental studies on the material, the Stable Isotope Materials and Chemistry Group (SIMC) at Oak Ridge National Laboratory (ORNL) was approached to develop a safe method to process thallium and produce 40 non-isotopic thallium foils. The commercially sourced metal was consolidated into an ingot by melting the material in a special tube furnace under a reducing atmosphere. The resulting ingot was cold rolled using a work-hardened, stainless-steel pack and oil lubricant before cutting the final foils to 2.5 × 2.5 cm2 area and thickness of 50–75 mg/cm2. The appropriate safeguards used at each step are outlined to ensure the safe and consistent production of high-quality foils. The low-loss process enables future requests for isotopic thallium and other hazardous and rare materials.

New concept of cast iron melting technology in induction crucible furnace

The article considers methods for reducing harmful impurities in the composition of synthetic cast iron (SCI) and improving the strength characteristics of cast iron. A new method for smelting SCI using steel scrap as charge materials in induction crucible furnaces is proposed, including filling of metal charge, together with transfer cast iron, return of own production, carburetors, and ferroalloys to carburize and alloy up to the required chemical composition. It is revealed that with an increase in steel scrap in the metal charge, the melting time, specific power consumption, melting duration, hardness of the experimental sample increase, and the yield of usable liquid cast iron decreases. To achieve the required hardness of the experimental sample, it is necessary to have мeтaллoшихтefrom 10 to 40% of steel scrap in the metal charge.

High-temperature X-ray diffraction study of anorthite-tialite materials

ABSTRACT The structure of two mixtures of anorthite and tialite (10 mol-% tialite + 90 mol-% anorthite, 15 mol-% tialite +85 mol-% of anorthite) has been investigated using XRD at different temperatures in solid and liquid states. Such mixtures are used as refractory materials in the lining furnaces for metals with a high melting point. All measurements were carried out using a high-temperature vacuum chamber under a purified helium atmosphere. It has been found that the XRD patterns of the solid samples show reflections of various modifications of tialite and anorthite. Weak reflections of mullite can be identified at temperatures above 1000°C. A structural model of the investigated melts has been proposed based on nanocrystal clusters located in a disordered diffuse matrix. The environment of the disordered part of the matrix is formed by particles (atoms, atomic clusters) that do not participate in nanocrystal clusters.

A New Hydrometallurgical Process for Metal Extraction from Electric Arc Furnace Dust Using Ionic Liquids

This research proposes a new hydrometallurgical method for Zn, In, and Ga extraction, along with Fe as a common impurity, from electric arc furnace dust (EAFD), using ionic liquids. EAFD is a metal-containing waste fraction generated in significant amounts during the process of steelmaking from scrap material in an electric arc furnace. With valuable metal recovery as the main goal, two ionic liquids, [Bmim+HSO4-] and [Bmim+Cl-], were studied in conjunction with three oxidants: Fe2(SO4)3, KMnO4, and H2O2. The results indicated that the best combination was [Bmim+HSO4-] with [Fe2(SO4)3]. An experimental series subsequently demonstrated that the combination of 30% v/v [Bmim+HSO4-], 1 g of [Fe2(SO4)3], S/L ratio = 1/20, a 240 min leaching time, and a temperature of 85 °C was optimal, resulting in maximum extractions of 92.7% Zn, 97.4% In, and 17.03% Ga. In addition, 80.2% of the impurity metal Fe was dissolved. The dissolution kinetics of these four elements over a temperature range of 55-85 °C was found to be diffusion controlled. The remaining phases present in the leached residue were low amounts of ZnO, Fe3O4, ZnFe2O4, and traces of Ca(OH)2 and MnO2, and additional sharp peaks indicative of PbSO4 and CaSO4 appeared within the XRD pattern. The intensity of the peaks related to ZnO and Fe3O4 were observed to have decreased considerably during leaching, whereas some of the refractory ZnFe2O4 phase remained. SEM-EDS analysis revealed that the initial EAFD morphology was composed of spherical-shaped fine-grained particle agglomerates, whereas the leached residue was dominated by calcium sulphate (Ca(SO4))-rich needle-shaped crystals. The results clearly demonstrate that [Bmim+HSO4-] is able to extract the target metals due to its acidic properties.

Erosion Behavior and Longevity Technologies of Refractory Linings in Blast Furnaces for Ironmaking: A Review

Erosion of the refractory materials in blast furnaces (BFs) greatly limits their campaign life, which seriously reduces the economic benefits of iron and steel plants and endangers workers. Therefore, it is important to detect and monitor the erosion process of refractory materials in the BF hearth. In this review, the mechanisms of physical damage, chemical corrosion, and mechanical erosion of BF hearths during BF operation are analyzed and summarized. In addition, the effects of hearth structure, refractory type, and protective layer on hearth erosion behavior and hearth life are analyzed and discussed. Some longevity technologies of BF hearths are analyzed and compared, such as reasonable hearth structure design, refractory selection, and technologies to form protective layers. Finally, some suggestions and prospects for the future development of long campaign life BF hearths are discussed.