Melting Furnace Research Articles

Research on the reaction behavior of pellets in typical atmospheres of shaft furnaces: Reduction swelling and carbon deposition

In this work, the volume swelling and carbon deposition behavior of pellets under shaft furnace smelting conditions were studied. The research process on swelling reduction utilized an online detection imaging method to determine the volume changes of pellets. The results suggest that an increase in temperature and a higher proportion of carbon monoxide in the reducing gas contribute to an escalation in the swelling rate during pellet reduction. Carbon deposition induced by carbon monoxide primarily occurs at 750 °C, and the powdery carbon deposition products on the surface of the pellets change over time, transitioning from carbon to a mixture of carbon and iron carbide (Fe3C) to a mixture of carbon, Fe3C, and metallic iron. This study elucidated the behavior of pellets in the low-temperature reduction section during the shaft furnace smelting process, offering a technical foundation for shaft furnace smelting technology.

Comparative Studies of the Physico-Mechanical Characterization of Ugwuoba Clay with Admixtures of Corncob and Sugarcane Bagasse Ashes

An investigation into the effects of combustible materials on the refractory properties of Ugwuoba clay, using sugarcane bagasse ash and corncob ash has been undertaken. Ugwuoba clay was sourced from Ugwuoba town in Oji River Local Government Area of Enugu State. Sugarcane bagasse were collected at Lokpanta, a Fulani settlement in Okigwe Community, Imo State, while corncobs were collected at New Artisan Market in Enugu Metropolis. The clay was processed using standard beneficiation and purification procedures at the Ceramics Department of Projects Development Agency (PRODA), Enugu. The sugarcane bagasse and corncobs were each and separately calcined into amorphous ash by heating in a furnace at 650oC. The refractory blends were compounded at the ratio of 90:10, 80:20, 70:30, and 60:40 for Ugwuoba clay (UGC) to Sugarcane Bagasse Ash (SBA) and Ugwuoba Clay (UGC) to Corncob Ash (CCA) separately and respectively. These blends were subsequently molded into the standard test pieces for the various properties determination and subjected to firing at temperatures of 900oC, 1000oC, 1100oC and 1200oC. Thereafter, the fired samples were characterized for fired shrinkages, total shrinkages, apparent porosities, water absorption coefficients, apparent densities, bulk densities and moduli of rupture. The results obtained for each of the blends showed that the values were within the tolerable limits for industrial refractories with the 10%SBA and the 20%CCA blends showing the best results. Comparatively however, the 10%SBA produced the better of these properties than the 20%CCA. A conclusion is drawn to the effect that both sugarcane bagasse ash and corncob ash can serve as good organic admixtures for refractory bricks production for the lining of melting furnaces in the metals industry, hence opening new frontiers for recycling of these agricultural wastes for environmental safety and economic development in Nigeria.

Optimizing pre-reduction of vanadium–titanium magnetite through recycling and integrating of top gas from melting furnace and tail gas from rotary kiln

In this study, the pre-reduction impact of CO and H2 on vanadium–titanium magnetite (VTM) was examined considering the composition of the top gas of the melting furnace. Additionally, the recycled and upgraded tail gas from the rotary kiln was mixed with the top gas of the melting furnace to enhance the pre-reduction effect and meet the temperature requirements of the rotary kiln. By analyzing the variations in the tail gas composition, the possible reactions occurring during the VTM pre-reduction process were determined. The results demonstrate the crucial role of H2 in the reduction process. A 20% H2 concentration yields a reduction effect similar to that achieved with 55% CO, resulting in a complete reduction of magnetite. However, the presence of CO2 in the gas hinders the reduction reaction by decreasing the reduction capacity of CO or inducing a secondary oxidation of the reduction products. Furthermore, the introduction of half of the tail gas of the rotary kiln into the top gas of the melting furnace increases the metallization rate of VTM pellets from 37.84% to 57.2%. These findings provide valuable references for utilizing the high-temperature top gas of the melting furnace for VTM pre-reduction in rotary kilns.

Effects of cold deformation and aging on the phase transformation and mechanical properties of a Cu-15Ni-8Sn alloy

A Cu-15Ni-8Sn alloy ingot was prepared in a medium-frequency induction melting furnace. First, the hot extruded alloy was subjected to solution treatment at 840 °C for 60 min, after which cold drawing treatment was applied under different deformation conditions (0–70%). Finally, the cold-deformed alloy was subjected to aging at different temperatures (340–520 °C) and insulation times (0–480 min). The evolution of grain characteristics, micromorphology and mechanical properties during cold drawing deformation and aging were systematically studied. The results show that during cold drawing deformation, the grains in the solid solution Cu-15Ni-8Sn alloy gradually elongate along the drawing direction with increasing deformation, and the texture changes from a discrete distribution to a hard orientation. Cold drawing deformation promoted coarsening of the modulated structure and the transition of the D022 ordered phase. Dislocations and twins increased the occurrence of nucleation for the discontinuous precipitates and promoted the growth of the discontinuous precipitates, but cold deformation inhibited the transition of the D022 ordered phase to the L12 ordered phase. The hardness, tensile strength and elongation of the Cu-15Ni-8Sn alloy after 50% cold deformation were 109.2 HRB, 1258.3 MPa and 7.5%, respectively, after aging at 400 °C for 60 min. The main strengthening mechanisms of the peak-aged alloy were precipitation strengthening and dislocation strengthening.

Effects of the Addition of Corncob Ash on the Technological Properties of Ugwuoba Clay, Nigeria

An investigation into the effects of combustible materials on the refractory properties of Ugwuoba clay, using corncob ash has been undertaken. Ugwuoba clay was sourced from Ugwuoba town in Oji River Local Government Area of Enugu State, Nigeria, while corncobs were collected at New Artisan Market in Enugu Metropolis. The clay was processed using standard beneficiation and purification procedures at the Ceramics Department of Projects Development Agency (PRODA), Enugu. The corncobs were calcined into amorphous ash by heating in a furnace at 650oC. The refractory blends were compounded at the ratio of 90:10, 80:20, 70:30, and 60:40 for Ugwuoba clay (UGC) to Corncob Ash (CCA) respectively. These blends were subsequently moulded into the standard test pieces for the various properties determination and subjected to firing at temperatures of 900oC, 1000oC, 1100oC and 1200oC. Thereafter, the fired samples were characterized for fired shrinkages, total shrinkages, apparent porosities, water absorption coefficients, apparent densities, bulk densities and cold crushing strengths. The results obtained for each of the blends showed that the values were within the tolerable limits for industrial refractories with the 20%CCA blends showing the best results when compared with the other blends. A conclusion is drawn to the effect that corncob ash can serve as good organic admixtures for refractory bricks production for the lining of melting furnaces in the metals industry, hence opening new frontiers for recycling of these agricultural wastes for environmental safety and economic development in Nigeria.

Systematic Study on the Microstructures of Biomedical Co–20Cr–15W–10Ni Alloys with Carbon Contents Ranging from 0 to 0.2 mass pct

Herein, the effect of carbon content on the microstructures of Co–20Cr–15W–10Ni (mass pct, CCWN) alloys was systematically studied. For this, CCWN alloys with carbon contents of 0, 0.05, 0.10, and 0.20 mass pct, i.e., 0C, 0.05C, 0.10C, and 0.20C alloys, respectively, were prepared using an induction melting furnace. The as-cast alloys were solution treated at 1523 K for 7.2 ks, followed by cold swaging and heat treatment at 1173 K–1473 K for 0.15–7.2 ks. Consequently, η-phase (M6C-M12C type, M: metallic element) precipitates were detected in the as-cast 0.10C and 0.20C alloys, whereas no precipitates were observed in the 0C and 0.05C alloys. These precipitates were dissolved via a solution treatment. After cold swaging, the ε-phase formed through a strain-induced martensitic transformation in the 0C and 0.05C alloys. Following heat treatment, a single γ-phase matrix was observed in all the alloys, and μ-phase (Co7W6-type) and η-phase precipitates were observed in the 0C and carbon-added alloys, respectively. The precipitation temperature range of the η-phase increased with increasing carbon content. The stability of the precipitates qualitatively conformed with that of the calculated phase diagram. This is the first paper that reports the microstructural changes in CCWN alloys with varying carbon contents.

Improved oxidation resistance while maintaining slag corrosion resistance of MgO–SiC–C refractories with moderate amounts of liquid phase

AbstractMgO–SiC–C refractories with superior hot strength, oxidation resistance and slag resistance have potential to become substitute refractories for matte smelting furnace. In the present work, the influence of glass powder addition on phase compositions, hot strength, oxidation resistance, and slag resistance of MgO–SiC–C refractories was investigated. The liquid phase introduced by glass powder filled the pores, blocking the channel for the ingress of the oxygen and thus improving the oxidation resistance. Although the oxidation resistance of such refractories was improved with 1–3 wt% glass powder addition, their hot strength and slag corrosion resistance decreased when the glass powder content was 2–3 wt%. To balance the mechanical properties, oxidation resistance and slag resistance, low amount glass powder addition (1 wt%) was considered better choice.

Multiphysics modeling and experimental validation of heat and mass transfer for the vacuum induction melting process

Vacuum induction melting is crucial in casting nickel-based superalloy components, ensuring excellent properties for aero-engine applications. Precise melting temperatures are vital for achieving optimal metallurgical quality before casting. Hence, a multiphysics numerical model is developed to simulate the induction melting process for the Inconel 718 superalloy. The proposed holistic model integrates magnetic fields, induced currents, and heat and momentum transfer phenomena in a single coupled model. A moving mesh approach reproduces the magneto-hydrodynamic behavior of the free surface, simulating the oscillations of the melt. The stabilized deformed surface profile is correlated with experimental measurements, reporting a proper correlation. Then, the flow field and recirculation effect are modeled with a Low Reynolds Number turbulence approach and coupled with the melt convective heat transfer, developing a complete magneto-thermo-hydrodynamic model. In a laboratory-scale vacuum induction melting furnace, transient melting operation variables are characterized and introduced to the numerical model to compute the temperature evolution. An accurate reproduction of the transient melt temperature variations is reported with a relative error of less than 5%. The influence of the crucible thermal insulating capacity is assessed, emissivity dependence evaluated, and melt homogenization is reported at different process stages. This comprehensive numerical and experimental approach offers valuable insights for enhancing vacuum induction melting for Ni-based superalloys.

Improving Mechanical Properties of Co-Cr-Fe-Ni High Entropy Alloy via C and Mo Microalloying.

The as-cast [Co40Cr25(FeNi)35-yMoy]100-xCx (x = 0, 0.5, y = 3, 4, 5 at.%) HEAs (high-entropy alloys) were prepared by a vacuum arc melting furnace and were then hot rolled. The effect of C and Mo elements on the microstructure evolution and mechanical properties of HEAs was systematically analyzed. The results showed that when no C atoms were added, the HEAs consisted of FCC + HCP dual-phase structure. In addition, as the Mo content increased, the grain size of the alloy increased from 17 μm to 47 μm. However, only the FCC phase appeared after adding 0.5 at.% carbon in Mo microalloyed HEAs, and the grain size of the Mo4C0.5 HEA decreased significantly. Due to the Mo atom content exceeding the solid solution limit, the carbides of Mo combined with the C element appeared in the Mo5C0.5 HEA. The strength of C and Mo microalloyed HEAs significantly increased compared to HEAs with no C added. However, the Mo4C0.5 HEA exhibited excellent comprehensive mechanical properties, which was superior to a majority of reported HEAs and conventional metal alloys. Its yield strength, tensile strength, and elongation were 757 MPa, 1186 MPa, and 69%, respectively. The strengthening mechanism was a combination of fine grain strengthening, TWIP effect, and solid solution strengthening.

Role of Exergy‐Based Process Evolution for Sustainable Steel Making: Rotary Hearth Furnace with Electric Arc Furnace Smelting

In conjunction with an electric arc furnace (EAF) process, a rotary hearth furnace (RHF) has emerged as a supplementary ironmaking unit to produce extra iron from iron‐bearing solid wastes from an integrated steel plant. Additionally, such units offer fuel‐switching options to low‐carbon input fuels. Exergy analysis is carried out for two variants of RHF, producing iron nuggets (ironmaking technology mark 3 process) or direct reduced iron (DRI; FASTMET process), involving cold/hot charging of DRI and scrap use in EAF. Process sustainability as characterized by higher exergy efficiency and lower CO2 emission has been analyzed for two variants of RHF‐EAF steelmaking systems, blast furnace‐basic oxygen furnace (BOF), scrap‐EAF, and COREX‐BOF process. Model‐based information for these parameters for RHF‐EAF process has been compared with other major steelmaking routes based on literature information. The RHF‐EAF process variants with some modification in process flow display better sustainability with relatively higher exergy efficiencies and low CO2 emissions as compared to other steelmaking processes and reasonably meet sustainable steelmaking process evolution criterion.

Space numerical simulation of full oxygen combustion flame in glass melting furnace based on flue gas preheating

This study explores the innovative design of a glass-melting furnace, which incorporates a combustion lance and a flue on one side. The research validates the simulation that the high-temperature flue gas, produced by the pure oxygen combustion of natural gas, can utilize residual heat in a multi-stage process to preheat and burn the fuel natural gas via a jet heat pump. This process significantly reduces energy consumption, thereby decreasing construction costs and energy usage in industries related to glass furnace production. The research focuses on the flame space of a 600 t/day natural gas flat glass all-oxygen combustion furnace. Utilizing numerical calculation methods, a three-dimensional mathematical model of the all-oxygen lance flame space was developed. Numerical simulation methods were employed to examine the temperature field, airflow field, and the distribution pattern of the liquid flow field within the glass space in the furnace. The simulation results reveal that incorporating high-temperature flue gas into the fuel can markedly enhance the performance of the spray gun flame. Additionally, choosing spray gun outlet designs of varying widths can tailor the flame width to better meet the requirements of the glass melting system, thereby significantly improving the waste heat utilization rate of the flue gas. This offers more alternatives for the direct utilization of flue gas. When compared to traditional oxy-combustion glass melting furnaces, this innovative design substantially reduces construction costs and is more energy-efficient and environmentally friendly.

Ignition and combustion of synthetic nickel mattes in simulated flash smelting conditions

The ignition and oxidation behavior of synthesized sulfur-lean nickel mattes was investigated using a laminar flow furnace simulating the conditions in the flash smelting reaction shaft to explore the ignition and oxidation processes of sulfur-lean electric furnace mattes obtained from slag cleaning. The experiments were conducted at 800–1100 °C with 40–85 vol% O2 in the reaction gas. Scanning electron microscopy equipped with energy-dispersive X-ray spectrometry was used to analyze the surface morphology and mineralogical compositions of the samples. Chemical analysis was employed to determine the sulfur remaining in the samples. The ignition temperature of the sulfur-lean nickel mattes was found to be below 800 °C. The highest sulfur removal from mattes was achieved under the most oxidizing conditions. The oxidation of the metallized nickel mattes started with preferential oxidation of iron and sulfur, forming sulfur dioxide and a porous iron oxide-rich rim. Particles were observed to melt completely and even to fragment due to fast combustion reactions and the formation of sulfur dioxide inside. The present results provide valuable insights into the mechanism of sulfur-lean nickel matte smelting in flash smelting furnaces.

Combustion behavior of co-injecting flux, pulverized coal, and natural gas in blast furnace and its influence on blast furnace smelting

The integration of advanced high-ratio pellet ore smelting technology with flux injection at the blast furnace tuyere offers significant carbon emission and air pollution reductions for iron and steel manufacturers. This study presents a comprehensive thermogravimetric analysis and burnout rate assessment of Russian Bituminous Coal (RB) and flux mixtures across varying mass ratios, alongside a detailed exploration of the catalytic mechanisms of three distinct fluxes on RB combustion. The findings reveal that lime, when added to the coal-flux blend, markedly enhances the overall combustion characteristic index and catalytic impact, more so than limestone or dolomite. The optimal lime admixture of 5 % resulted in a peak S value of 6.30 and a burnout rate of 70.63 %, constituting an increase of 7.64 % over the base case without flux. Lime's superior catalytic performance is attributed to its higher content of calcium-containing compounds, which amplify catalytic activity through increased Ca2+ ion exchange with carboxyl groups. Mathematical model calculations considering the combustion rate of the pulverized coal show that: after the addition of 5 % lime, there is a 133.43 t/d increase in iron production, compared to the 11,323.98 t/d without the addition of flux. When the lime addition amount is 7 %, the proportion of sintered ore in the blast furnace decreases by 6.53 %, and the coke saving is 2.8 kg/t. This research is expected to enhance the understanding of pulverized coal combustion when amalgamated with basic fluxes and serve as a theoretical foundation for optimizing industrial applications.

Optimization of pyroprocessing of zinc sulfide ore to produce ferroalloy and zinc

The article presents the results of thermodynamic analysis and experiments on the electric smelting of Shalkiya ore (5.2% of ZnS, 1.0% of PbS, 50% of SiO2) with the joint producing a silicon-containing ferroalloy and extracting zinc and lead into sublimates. The studies included the thermodynamic modeling using the HSC-6.0 software package and electric smelting in an arc furnace. It was established that the interaction in a ZnS-Fe3O4-2C system under equilibrium conditions is of a stepwise nature with the initial reduction of Fe3O4 to Fe and FeO at 600-1000 °C, then the interaction of ZnS with Fe at 1100-1800 °C with the formation of gaseous zinc, and the interaction of ZnS with FeO with the predominant formation of zinc at temperatures above 1600 °C. The electric smelting a charge containing the Shalkiya ore, coke, magnetite concentrate (85.9% of Fe3O4) and steel shavings allowed us to establish that FeSi45 grade ferrosilicon (41.8-44.6% of Si), with the extraction of 80-85.4% of Si, can be produced in the presence of 24.9-30% of coke with the replacement of magnetite’s iron by steel shavings’ iron from 20.9 to 91.8%. A lower degree of this replacement is associated with intensive development of foaming and a decrease in the extraction of silicon into the alloy. At least 98% of zinc and 96% of lead are extracted into the resulting sublimates containing 29.4% of zinc and 15.1% of lead.

ПОВЫШЕНИЕ ЭФФЕКТИВНОСТИ ИСПОЛЬЗОВАНИЯ ЭЛЕКТРОЭНЕРГИИ НА ГОРНЫХ ПРЕДПРИТИЯХ

The paper presents the results of a comprehensive energy audit at the nickel plant, one of the structural divisions of MMC Norilsk Nickel. A structural diagram of the plant's power supply is presented, the dynamics of electricity consumption is shown, showing that the main electricity consumption at the enterprise goes to the production of nickel (69% from the sinter and 21% from the Nadezhda Metallurgical Plant). Analysis of the dynamics of changes in electricity consumption for the main technological processes of nickel production from sinter shows a pronounced dependence of changes in the volume of electricity consumption for the production of sinter and smelting in ore-thermal furnaces. An analysis of the operation of electric drives with voltages of 0.4 kV and 6 kV is presented, for which the load parameters of the most powerful motors in the technological shops of the enterprise were recorded. It has been established that in order to increase the efficiency of energy use, as well as to reduce the influence of the electric drive on the load losses of the supply network, it is necessary to consider: the possibility of replacing individual, most unloaded motors with motors of lower power or the use of frequency control of the performance of process equipment...

The Ongoing Sungai Jaong Archaeological Project (2018‑2024), Sarawak, Malaysia: Preliminary Results

More than fifty years after the last excavations undertaken in the coastal area of the Sarawak River Delta, new archaeological excavations in the region started in 2019, through a cooperation between the École française dʼExtrême-Orient and the Sarawak Museum Department. This article offers the preliminary results of researches conducted at the Sungai Jaong site, in the Santubong area, until late 2023. Despite a very limited excavated surface area, the conduct of metallurgical activities in ancient times has been recognised and attested without any doubt for the first time in the Sarawak River Delta. Several remains of iron smelting furnaces, dated between mid-11th and late 12th-13th century CE, have been uncovered. They could represent the first iron smelting furnaces, dated to early second millennium CE, reported so far on the whole island of Borneo. Other finds include notably more than seven tons of iron slag, some 3,200 fragments of tuyeres, 6,600 earthenware sherds, almost 2,500 stoneware shards, and several grooved stones. Various analyses of these finds are underway, including a compositional analysis of iron slag samples. Archaeological research at Sungai Jaong also includes a geomorphological study to shed light on the interactions between the ancient occupation of the site and the environment over the longue durée.

Anomaly Detection of Industrial Smelting Furnace Incorporated With Accelerated Sampling Denoising Diffusion Probability Model and Conv-Transformer

Anomaly Detection of Industrial Smelting Furnace Incorporated With Accelerated Sampling Denoising Diffusion Probability Model and Conv-Transformer

ОСОБЕННОСТИ РАБОТЫ ДОМЕННОЙ ПЕЧИ НА АГЛОМЕРАТЕ РАЗНОЙ ОСНОВНОСТИ

The paper shows the peculiarities of blast furnace performance when different types of iron ore material are used. It is noted that the main types of iron ore raw materials are sinter and pellets, their advantages and disadvantages are given. The influence of increased pellet consumption on blast furnace smelting is indicated. The influence of sinter basicity on its strength and recoverability is noted. The results of calculating the indicators and the operation mode of the blast furnace at increased sinter basicity and an increased ratio between its consumption and pellets are presented.

Effect of magnesium content on plastic properties and internal defects of 708 alloy ingot

The effect of magnesium content on defect rates and yield in bar billets made of 708 alloy obtained by the electric arc furnace smelting, vacuum arc remelting forging method under the conditions of Stupino Metallurgical Company is determined. The effectiveness of the effect on the properties of the alloy is assessed at constant technological parameters of smelting in electric arc furnace and subsequent vacuum arc remelting using statistical analysis based on 92 industrial melts. The presented statistical results of a wide array of melts made it possible to clarify the required optimal magnesium content in the 708 alloy at the stage of producing it in electric arc furnace. It is established that optimal magnesium content allows to obtain a high yield, as well as minimal defects in internal defects identified using ultrasonic testing.

ОРГАНІЗАЦІЙНО-ЕКОНОМІЧНІ МЕХАНІЗМИ РОЗВИТКУ БІЗНЕС-СЕРЕДОВИЩА НА ПІДПРИЄМСТВАХ МОРСЬКОГО ФУНКЦІОНУВАННЯ У ПОВОЄННИЙ ПЕРІОД

Today, the ongoing full-scale invasion of the Russian into Ukraine has caused significant financial, human, migration and political losses to various sectors of the economy of Ukrainian enterprises. In the opinion of the authors, development strategies should be applied in the post-war period of enterprises, losses should be restored through organizational and economic mechanisms of business plans and projects. The advantages of this product can significantly reduce the costs of relevant specialized enterprises in the regional and global shipping market, thereby reducing the cost of marine melting furnaces and increasing their productivity. As a result of research and industrial tests of the product offered by these enterprises, which allow us to guarantee that the stated requirements for the specified technological cover have advantages over analogues. The analysis shows that the beneficiaries of the offered products are: shipping companies, transport companies, technological companies engaged in the production of products for maritime organizations based on infrastructural components. Currently, representatives of the company are conducting negotiations with counterparties regarding the licensed production of ship covers in European and Asian countries. The article examines the current tasks of developing approaches to the strategy of creating projects on the example of the enterprise "Rial-morterminal" for the production of special products and proving its organizational and economic efficiency, planning of human resources at the enterprise. The goal is to develop a strategy based on the example of the company "Rial-morterminal", the production of products that have the advantages of the two types of specialized ship covers mentioned above. The authors investigated SWOT analysis and product risk analysis of marine melting furnaces for all types of ships. The risks of the project were studied: with a ranking of the impact on the project, conditions of risks for the creation of the production of the specified enterprise, a product that has the advantages of the two types of covers for (boilers, furnaces) of the main power plant of sea and river vessels in the regions of Ukraine in the post-war period.