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Interfacial reactions between the electric arc furnace (EAF) slag, i.e., CaO–SiO2–FeO–MgO–Al2O3–MnO system, and the magnesia refractory as a function of direct reduced iron (DRI) addition (0, 10, 20, 30 wt%) were investigated at 1550 °C under an Ar atmosphere. MgO solubility increases with increasing DRI content by decreasing basicity (i.e., CaO/SiO2 ratio), which is due to an increase in SiO2 supplied from DRI. The measured MgO content was always lower than the theoretical MgO saturation level irrespective of DRI content because the magnesiowustite (MW) intermediate layer, which formed at the slag/refractory interface, retarded the direct dissolution of the refractory by acting as a self-protective layer. The thickness of the MW intermediate layer and dissolution depth were proportional to DRI content. However, the penetrativity decreased with increasing DRI content by decreasing the fluidity of the slag. Several kinetic parameters were estimated, including the dissolution rate constant of the MW intermediate layer, the dissolution rate of the MgO refractory, and the rate constant of MW growth. Dissolution of MgO refractory is controlled by the dissolution of the MW intermediate layer. Increasing the growth rate is very important for protecting refractory after the formation of a MW intermediate layer. In addition, we provided a schematic diagram of the slag/refractory interfacial reaction phenomena that compares situations of low and high DRI content. The results of the present study show that it is necessary to control DRI content to minimize refractory degradation during the EAF process. If a large amount of DRI must be used in the EAF process, then MgO content in the slag should be at the saturation limit at first, which accelerates growth of the MW intermediate layer.

Electric arc furnaces (EAFs) are used for steel production, particularly when recycling scrap material. In EAFs, carbonaceous material is charged with other raw materials or injected into molten slag to generate foam on top of liquid metal to increase energy efficiency. However, the consumption of fossil carbon leads to greenhouse gas emissions (GHGs). To reduce net GHG emissions from EAF steelmaking, the substitution of fossil carbon with sustainable biogenic carbon can be applied. This study explores the possibility of the substitution of fossil material with biogenic material produced by different pyrolysis methods and from various raw materials in EAF steelmaking processes. Experimental work was performed to study the effect of biogenic material utilization on steel and slag composition using an induction melting furnace with 50 kg of steel capacity. The interaction of biogenic material derived from different raw materials and pyrolysis processes with molten synthetic slag was also investigated using a tensiometer. Relative to other biogenic materials tested, a composite produced with densified softwood had higher intensity interfacial reactions with slag, which may be attributed to the rougher surface morphology of the densified biogenic material.

The effect of slag composition under M’O (monoxide, M = Fe,Mg) saturation and fully liquid conditions on dephosphorization and slag foamability was evaluated in an electric arc furnace (EAF) steelmaking plant operation by considering thermodynamics and phase equilibria. It was confirmed that M’O saturation slag is more favorable for higher dephosphorization than fully liquid slag due to its high activity of CaO as a thermodynamic driving force. As a quantitative measure of slag foamability, the foaming index was clearly dependent on the temperature and slag composition. Moreover, foam stability was evaluated by applying the predominance stability diagram based on phase equilibria. Consequently, it can be suggested that an efficient direction for dephosphorization and slag foaming during the EAF process is to generate high CaO activity as well as small amounts of M’O monoxide and dicalcium silicate (Ca2SiO4) compounds.

To recover zinc from electric arc furnace (EAF) dust, a process of primary normal pressure leaching and secondary alkaline pressure leaching is proposed. First, under the alkaline pressure leaching system, the experiment of pure zinc ferrite being reduced by iron powder was carried out. Under the optimal reduction conditions (i.e., temperature of 260 °C, NaOH concentration of 6 mol/L, liquid-to-solid ratio of 50 mL/g, and a 5-fold excess of iron powder), 89% of zinc was extracted. The iron in the reduced residue exists as a magnetite phase. Subsequently, the normal pressure leaching experiment was carried out with EAF dust as raw material, and 66% zinc was leached. The main phase of zinc in normal leaching residue was determined to be zinc ferrite. Then, the normal leaching residue was reduced by iron powder under the alkaline pressure leaching system, and 66.5% of zinc was extracted. After the two-stage leaching process, the leaching rate of zinc in EAF dust can achieve 88.7%. The alkaline pressure leaching solution can be returned as the normal pressure leaching solution, and the magnetite in the alkaline pressure leaching residue can be recovered by magnetic separation.

The European Green Deal aims to make Europe climate neutral by 2050. This circumstance requires the metallurgical industry to move from carbon-based processes to hydrogen application. This work aims to summarize the current state of the research on thermodynamics and reaction kinetics in the scope of hydrogen-based reduction for Electric Arc Furnace Dust and present already existing and theoretically possible recycling processes using hydrogen. Thermodynamic calculations suggest three possible approaches to treat Electric Arc Furnace Dust using hydrogen as a reducing agent: Full reduction of iron and zinc oxide, selective reduction of iron oxide, and selective reduction of zinc oxide. In general, hydrogen can replace carbon seamlessly, leading to higher reaction kinetics but also to higher processing costs due to the high hydrogen price currently. However, zinc extraction from Electric Arc Furnace Dust allows for innovative concepts such as hydrogen recovery by reoxidation of gaseous zinc with water. In combination with selective zinc oxide reduction, this approach results in a recycling process with a low hydrogen consumption. However, additional high-quality research is necessary to provide a better data basis for a detailed economic view.

Iron/steel making industry is a weed that produces large quantities of slag and dust. The objective of the present study was to develop a procedure for obtaining and characterizing photocatalysts derived from this waste for chromium remediation. The MCM-41 was synthesized via sodium silicate (Na2SiO3) derived from Blast Furnace Slag (BFS), and ZnO and ZnS were synthesized based on zinc extracted from Electric Arc Furnace Dust (EAFD). Subsequently, ZnO/ZnS were sono-chemically loaded on the MCM-41 and were tested for the Cr (IV) photoreduction. The resultant ZnO, ZnS, MCM-41, and composites were characterized by X-ray diffraction (XRD), Energy-dispersive X-ray spectroscopy (EDX), N2adsorption–desorption isotherms, Fourier-transform infrared (FT-IR) spectrometry, Dynamic Light scattering, and Transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). A regular hexagonal structure of typical mesoporous MCM-41 had been proven by small-angle XRD, HRTEM, and N2 adsorption–desorption. The photoreduction activity of ZnS–ZnO/MCM-41 nanocomposite has obvious efficiency compared to ZnO and ZnO/MCM-41, achieving a 94% photoreduction of Cr (VI) in 180 min under UV irradiation. The slight activity loss after 4 cycles (84.7%) reveals the good photoreduction properties of catalysts. Based on these results, ZnS–ZnO/MCM-41 composite material seems to be high efficiency, green, stable, environment, and economical alternative to be used as a photocatalyst for the reduction of Cr (VI).

A comprehensive investigation focusing on the effect of fresh EAFD on the setting of cement pastes was conducted. A new approach of using accelerators to counteract the extended retardation associated with using fresh EAFD was investigated. Two chloride-free chemical accelerators (CFCA), namely, calcium nitrite (CN) and calcium formate (CF) were used and their performance was benchmarked against calcium chloride (CC). Temperature profile was used for validating setting times by Vicat needle apparatus. Homogenization of fresh EAFD from different furnaces resulting in an average ZnO content of 15.1% was adopted to ensure consistent retardation in setting time. The use of an accelerator/homogenized EAFD ratio of 0.25 for CN and CF has shown significant reduction in setting time more than CC. Additional reduction was achieved with an increased ratio to 0.5. However, limited effect was noted for CN and CF with a further increase in the ratio compared to CC. Scanning electron microscope (SEM) was used to monitor the microstructure development of selected mixtures at early age. Finally, Prediction models were developed to predict the EAFD and CFCA effects on setting time. The results of this study are important in the quest to develop EAFD from waste byproducts into viable construction material.

The interfacial reaction between the CaO–SiO2–FeO–Al2O3–MnO–MgO-xCaF2 (CaO/SiO2 = 0.9–1.2, x = 0–10 wt%) type electric arc furnace (EAF) steelmaking slag and magnesia refractory was investigated. Using a microscopic analysis, the thickness of the (Mg,Fe)O, magnesiowustite solid solution (intermediate) layer at the slag/refractory interface was measured. The thickness of the solid solution layer is affected by both slag penetration and refractory dissolution. Since the CaF2 in the slag affects the interfacial reaction between the slag and the refractory, it impacts the thickness of the solid solution layer. In addition, the depth of refractory dissolution was determined by changing the MgO content in the slag, and the depth of slag penetration was also quantitatively measured. Through these experiments, the refractory corrosion-protection mechanism by the CaF2-containing EAF slag was identified. Finally, the critical CaF2 content (= approx. 3 wt%), which had no significant effect on refractory corrosion, was proposed.

The technology of melting and ladle treatment of pipe steels K56, 09G2S, and KEI55 is analyzed to determine the factors affecting the metal quality and the formation and removal of oxide nonmetallic inclusions (NIs). To determine the causes of increasing the phosphorus content in the metal in an ladle–furnace unit (LFU), we develop a mathematical model to calculate the slag mass entering the metal on tapping from an electric arc furnace (EAF) and remaining on the steel ladle walls from the previous heat. This model is based on a system of material balance equations. Fractional gas analysis and scanning electron microscopy with electron-probe microanalysis are used to study the metal samples taken along the entire technological scheme of melting and ladle treatment of K56, 09G2S, and KEI55 pipe steels. The total content of oxygen and nitrogen in the selected metal samples, the characteristic types of oxide NIs, and their number are determined at each stage of ladle treatment and casting. The steel samples are shown to contain the most unfavorable for pipe steels undeformable NIs, namely, aluminates, aluminosilicates, and calcium aluminosilicates. The increase in the aluminum–magnesium spinel NI content in the metal samples is assumed to be due to the influence of deoxidizers and the inert gas flow rate on the destruction of the lining. The introduction of ferroniobium with an increase in the argon blowing intensity is found to decrease the nitrogen content in the metal due to the removal of formed titanium nitrides into a slag. The increase in the oxygen and nitrogen content in the samples taken from a continuous casting machine for the heats of 09G2S and KEI55 steels is assumed to indicate secondary oxidation of the metal on casting. A software package is developed using the C++ programming language and the Visual Studio environment in order to predict the number of various types of NIs having formed during ladle treatment depending on its conditions. The convergence of the calculated and experimental values is shown to be satisfactory.

The significant fraction of manganese ores available across the globe is ferruginous with high gangue content. About 30% of these types of ores occur as fines (

Rice husk ash (RHA) has been used to prepare high-purity silicon by a combination of a silicon preparation process and a refining process. Raw materials including RHA, silica sand and SiO2-CaO-Al2O3 slag were initially pelletized and then smelted in an electric arc furnace. The results show that slag refining and acid leaching have significant influences on purifying Si products. With the addition of slag, the purity of Si increased from 94.96% to 96.47% and the contents of impurities such as Fe and P reduced from 2.06 wt.% and 0.09 wt.% to 0.77 wt.% and 0.05 wt.%, respectively. After acid leaching, the purity of the Si increased to 99.76% and the content of P reduced to 0.029 wt.%. The leaching kinetics analysis results show that the surface chemical reaction model is suitable to describe the extraction process of Fe, Al, and Ca in silicon.

The current work is based on the process study and synthesis of value-added ferrous material from EAF (electric arc furnace) slag through reduction and melting using a waste carbon resource of spent coffee grounds. Spent coffee grounds were carbonized at 400°C to obtain transformed-spent coffee grounds. Pitch coke has also been used in the current study as a separate carbon source to compare the results obtained from using transformed-spent coffee grounds. A two-stages process has been employed in which a relatively low temperature of 1200°C was used to ensure solid-state reduction followed by melting at 1550°C. Overall, the performance of transformed-spent coffee grounds was better than that of pitch coke, thus giving rise to the potential utilization of waste materials like EAF slag and spent coffee grounds as secondary ferrous and carbon resources for iron and steelmaking applications.

In the recycling of zinc from electric arc furnace dust using microwave-based furnaces, the use of graphite powder as a reductant results in significant greenhouse gas emissions. In this study, graphite was replaced by a non-carbonaceous reductant in the form of silicon powder. The sample is heated in a microwave-based furnace under 7.5 kW maximum power irradiation at 2.45 GHz. The results clearly indicate that the reaction proceeded between zinc ferrite and silicon powder. The maximum removal rate of zinc obtained was 80% in cases where more than 10 times the stoichiometric amount of silicon powder was used for a heating time of more than 20 min. The apparent activation energy of microwave-based heating was 115.39 kJ/mol lower than that when heating with a conventional furnace.

The steel production generates approximately 10 % of electric arc furnace slag on the production of each ton of steel. In the view of environmental concerns and government regulations regarding slag disposal, alternate ways of its utilization are required. This work is focused on the leaching behaviour study of electric arc furnace (EAF) slag to assess its suitability as construction material. EAF slag contains toxic metals; consequently, their leachable quantity may affect the eco-system. Chromium (Cr), lead (Pb), mercury (Hg), molybdenum (Mo) and cadmium (Cd) have found special concern due to their high toxicity for human kind as well as for the environment. The leaching study of EAF slag was carried out through the application of sequential batch water leaching tests (SWLT), batch test and toxicity characteristics of leaching procedure (TCLP) method. Fresh EAF slag was characterized by XRF, XRD, SEM and ICPMS analysis for the determination of essential compositions and contamination. SWLT was performed at different pH of 4.0, 5.3, 6.1, 7.2 and 8.5. It was found that toxic metals was not leached beyond permissible limits at any pH. Moreover, TCLP method was applied for the leaching analysis of EAF slag at pH of 4.93 and 2.88. The concentrations of toxic metals in leachates were found negligible through ICP-OES analysis. The batch test method was also applied upto 60 days of EAF slag. This test was carried out at various pH ≈ 4, 5 and 6. The obtained leachates were tested at 10 days, 15 days, 30 days, 45 days and 60 days of leaching. The ICP-OES analysis of leachates showed negligible concentrations of leached metals/elements. Through the application of different leaching test methods, it was found that the leaching of hazardous heavy metals from EAF slag is negligible or within permissible limits as per IS 383−2016 and EPA. Therefore, EAF slag can be utilized as construction material in eco- friendly manner.

As a by-product of the steelmaking industry rich in iron and zinc, electric arc furnace dust (EAFD) landfill disposal is restricted in many countries due to the metal lixiviation risks. Several approaches have been examined to recycle or reuse EAFD. Hydrometallurgical methods mainly include the preparation of pregnant acid leached solution (PLS) using inorganic acids followed by selective metal recovery using different methods. We herein proposed a hydrometallurgical process initiated by acid leaching and finalized by thermal treatment to produce nano-ZnO from EAFD. At the condition of this study, only 67% of zinc was leached by sulfuric acid from EAFD into PLS while 98% of surplus leached iron was removed through precipitation by sodium hydroxide. Additional purification of iron removed PLS was accomplished using di-2 ethylhexyl phosphoric acid to extract Zn+2. The addition of ammonium hydroxide to purified PLS provided (Zn(OH)2)3(ZnSO4)(H2O)5 as the final precursor for nano-ZnO that ultimately transformed to nano-ZnO (60 ± 6 nm particle size) at 850 °C. The achieved results were scrutinized through various tests and analyses including TEM, XRD, SEM, EDS, FTIR, and TGA.

Data are provided for preparing fuzed and fuzed stabilized zirconia from baddeleyite and synthetic zirconia in induction, plasma, and electric arc furnaces. Results are discussed and prospects for carbothermal preparation of zirconium dioxide from zircon in an electric arc furnace are demonstrated. A favorable effect of oxidation melting in an electric arc furnace on quality and the process of fuzed product preparation is demonstrated. Data are provided for preparing fuzed zirconia from zircon in plasma furnaces.

A review of the literature on the development of electric steelmaking at metallurgical plants indicates the possibility and efficiency of combining arc melting of steel and its extra-furnace treatment by well-known methods. The possibilities of combined steel melting using metallized iron-ore raw materials (MIORM) and scrap metal, followed by extra-furnace treatment of liquid steel with inert gases and continuous casting of steel are analyzed. This study is novel in the use of gas afterburning and distributed feed of MIORM to the bath of an electric ladle furnace unit, partially or not using scrap metal. It is shown that the energy and technology features of the new ladle furnace during arc steel melting combined with extra-furnace treatment are comparable in efficiency and steel quality to those of a typical arc furnace.

The reaction kinetics, activation energy, and reduction rates of different carbon reductant properties with electric arc furnace (EAF) slag determine the effectiveness of carbon in EAF steelmaking. This article investigates the interaction between slag and carbonaceous materials derived from palm char and coke. Palm shells were converted into palm char using chemical activation method (phosphorus acid, H3PO4) and pyrolyzed at 450 °C for 2 h in a horizontal tube furnace. Then, all the carbonaceous materials were mixed with iron oxide from slag with mass ratio of 1:3.73. The reduction reaction was carried out in a horizontal tube furnace at different temperature ranges of 1250–1550 °C under argon gas to understand the reaction kinetics, activation energies, and reduction rates of iron oxide from EAF slag with palm char and coke. All iron oxides in EAF slag were completely reduced into metallic iron at 1550 °C for both reductants. The phase and quantity of reduced iron were confirmed by Rietveld refinement method using X-ray diffraction (XRD) pattern and energy-dispersive X-ray spectroscopy (EDX). Palm char/slag has lower activation energy value, E (38.52 kJ/mol), than coke/slag (47.75 kJ/mol). The reaction rate of palm char was found faster (4.99 × 10–5 mol/cm2 s) than coke due to larger specific surface area, higher pore volume, amorphous carbon structure, and higher fixed carbon with high volatile content leading to lower activation energy, thus accelerating the iron oxide reduction rates. This finding forms the basic understanding of the reaction between EAF slag and carbonaceous materials for future research on the production of palm char as a feasible carbon reductant in EAF steelmaking.

The article contains the research results of obtaining a ferroalloy from a carbon ferrochrome dust containing 30,2% of Сr2O3, 23.4% of SiO2, 32.7% of MgO, 5.0% of FeO, 1.6% of CaO, 4.5%of Al2O3, 2.3%of C, and 0.3 %-others. The studies were carried out by a thermodynamic modeling method using the HSC-5.1 software package (Outokumpy) based on the principle of the Gibbs energy minimum, the Box-Hunter rototable planning technique and electric melting of the dust in an arc furnace. It was found that the interaction of the dust with carbon under equilibrium conditions and in the presence of iron leads to formation of Cr4C(T>10000C),Cr3C2, Cr7C3,Cr (T>11000C), FeSi (T>13000C), SiC (T>14000C), SiOg and Si(T>15000C). In the temperature range of 1745-19000C and in the presence of 18-34% of carbon and 8% of iron of the dust mass, the resulting ferroalloy contained 18.5-25.2% of Si and 46.8-49.4% of Cr (in this case the silicon extraction degree into the alloy was 60.0-64.4%, the chromium one–99.8%). When the electrosmelting the granulated dust together with coke and steel shavings, the chromium extraction degree into the alloy was 98-99%, the silicon one–53-57%; the obtained ferroalloys containing 18.3-21.9% of silicon and 45.6-53.6%of chromium meet the requirements to FeCrSi23-grade ferrosilicochromium.

Silicon recovery of silica ore ( $$ {\text{SiO}}_{2} $$ ) has been studied with two types of carbon materials, charcoal as a biomass and coal as a fossil fuel, at elevated temperatures between 1800 and 2000°C in an electric arc furnace. The effects of porosity and electrical resistance of the carbon materials were investigated. To this end, recovery of silicon and ferrosilicon production were tested separately by charcoal and coal, and the products were investigated both qualitatively and quantitatively. A higher electrical resistance of charcoal was found in comparison with coal, with increased efficiency of the furnace and decreased electric energy consumption (per ton of product). The efficiency of the furnace using charcoal and coal was 92.13% and 77.4%, respectively. In addition, the higher porosity of charcoal facilitates the flow of SiO gas through the carbon material leading to a higher reactivity and reducing the electric energy consumption for each ton of FeSi.

Effective recycling of zinc-containing industrial wastes, most importantly electric arc furnace dust, is of tremendous importance for the circular economy of the steel and zinc industry. Herein, we propose a comprehensive kinetic model of the combined carbothermic and metallothermic reduction of zinc oxide in a metal bath process. Pyro-metallurgical, large-scale lab experiments of a carbon-saturated iron melt as reduction agent for a molten zinc oxide slag were performed to determine reaction constants and accurately predict mass transfer coefficients of the proposed kinetic model. An experimentally determined kinetic model demonstrates that various reactions run simultaneously during the reduction of zinc oxide and iron oxide. For the investigated slag composition, the temperature-dependent contribution of the metallothermic zinc oxide reduction was between 25 and 50 pct of the overall reaction mechanism. The mass transfer coefficient of the zinc oxide reduction quadrupled from 1400 °C to 1500 °C. The zinc recovery rate was > 99.9 pct in all experiments.

Herein, basic oxygen furnace (BOF) and submerged arc furnace (SAF) slags were used for the treatment of acid mine drainage (AMD). Their composition, complexity, and heterogeneity permits their application in AMD remediation. To fulfil the goals of this study, batch experimental approach was adopted. This was done using a 3.5 kl reactor equipped with a propeller. Characterization of feed and product minerals were done using X-ray fluorescence (XRF), X-ray diffraction (XRD), and High resolution scanning electron microscopy coupled with energy dispersive spectroscopy (HRSEM-EDS). The obtained results showed an increase in pH, which was proportionally linked to the interaction of AMD with the slags. The pH was observed to increase from 2 to 9.4, and 9.2 for BOF and SAF slags, respectively. Furthermore, the acquired pH was conducive for the removal of chemical species from the aquasphere. This was also confirmed by PH REdox EQuilibrium (in C language) (PHREEQC). Moreover, close to 99%-removal efficacy for Fe, Al, and Mn, and ≥50% removal efficacy for sulphate were noted for individual material. This confirms that these materials have the potential to give comparative outputs and effects. PH REdox EQuilibrium (in C language) (PHREEQC) confirmed the formation of metals hydroxide and gypsum from the interaction of slags and AMD. This corroborated the XRD, XRF, and HR-SEM-EDS results. In light of the obtained results, this comparative study proved that the steel slags from different industrial operations could potentially be used for the treatment of AMD. This initiative will go a long way in unpacking viable routes for valorization and beneficiation of steel slags hence minimizing their environmental footprints.

Silicon metal is one of the most important metals produced from silica by carbothermic reduction in the electric arc furnace which works at high temperatures between 1000 to 3000 oC. The objective of this work is to simulate the direct carbothermal reduction of SiO2 for Si metal by using a thermodynamic calculation of Gibb’s free energy minimization with MATLAB® and Aspen HYSYS®. The comparison of simulation using MATLAB® with reference [10] revealed close results. By increasing the mole ratio up to 10 increases the Si formation and increases the ratio more than 10 mole ratio had very bad results,and not economically viable. Here we did comparison between simulation results using MATLAB® with real assumption and ASPEN HYSYS®.

Steelmaking dust is one of the wastes which are produced by ironworks. This kind of waste is a byproduct produced mainly in electric arc furnace. Zinc content in dust is different and depends on the charge processed in the furnace. The basic technology used for recycling steelmaking dust is Waelz process, however, it requires a large amount of reducer and generates a lot of waste which needs to be stored. First stage in this study was to analyze if steelmaking dust was safe to be exposed to atmospheric conditions. To verify this, the dust was subjected to two kinds of standard leaching tests, TCLP and EN-12457-2. The amount of extracted elements was considerable and that was why steelmaking dust should be treated as dangerous waste. Leaching in citric acid solutions was divided in four series. The first one was set to determine the time and temperature for most selective zinc leaching. Next series optimized three leaching parameters which were: citric acid concentration, liquid to solid phase ratio (l/s), and the stirring speed. Performed experiments showed the optimal conditions for selective leaching: temperature of 50?C, leaching time of 60 minutes, citric acid concentration of 0.5 mol/dm3, l/s ratio of 10, and stirring speed of 250 rpm.

First flush having non-point pollutants have been increasing due to the increase in impermeable area by urbanization and industrialization, and there is a real difficulty in river water quality management due to CSOs and first flush. The purpose of this study is to optimize the phosphorus adsorption process using EAFRS as an adsorbent to improve the phosphorus reduction efficiency of CSOs. During the phosphorus adsorption reaction, the optimum conditions for the phosphorus adsorption process were derived by investigating the amount of phosphorus removal according to the slag particle size, surface modification and mixing intensity. According to the study, the smaller the slag particle size, the higher the phosphorus adsorption efficiency, and difference in phosphorus removal efficiency between the surface-modified slag using iron salts and the non-modified slag was not large as to whether surface was modified, But It was judged that iron ions and phosphorus prefer to bond more than that of phosphorus and calcium in surface modified slag. Under the mixing conditions with ceramic balls, the phosphorus removal rate tended to increase significantly, thus mixing method was judged to be a major factor in increasing the phosphorus adsorption efficiency. Lastly, FE-SEM, XRD and FT-IR analysis were performed to investigate the changes in the microstructure and chemical characteristics of the slag before and after phosphorus adsorption.

Abstract Recently, microwave energy has attracted increasing interest for accelerating thermal reactions. This study investigated the impact of microwave heating on the zinc recovery rate from electric arc furnace (EAF) and chromium converter (CRC) dusts. The results indicated that microwave heating required a lower temperature to recover zinc from EAF and CRC dusts compared with that in conventional thermal heating. For CRC dust, zinc recovery rates of 37.84% and 97.43% were obtained with conventional and microwave heating, respectively, at 850 °C. For EAF dust, zinc recovery rates of 79.88% and 98.20% were obtained with conventional and microwave heating, respectively, at 850 °C. The improved zinc recovery in this study was concluded to results from the rapidity of microwave heating and the interactions between the electromagnetic microwave field and the molecules of heated materials. Graphical Abstract

The corrosion resistance of the low-cement alumina base refractory against the slag of the electric arc furnace using zirconia was studied. Colloidal zirconia was replaced at the expense of the calcium aluminate cement by 1, 2, and 4 wt.% (C1, C2, and C4). The Andreasen coefficient of q = 0.23 was used to provide a reference sample with the 5 wt.% of the cement. The corrosion tests at 1620°C for 2 h were done and penetration zones were analyzed. In the case of samples prepared by colloidal zirconia, the penetration zone was enlarged due to the created porosity. The corrosion resistance of the C2 sample was improved. The new-formed calcium aluminate phase acts as a protective layer in the C2 sample. In the case of the C4 sample, the weight percentage of the calcium aluminate phase was significantly reduced. This can be related to the concentration gradient of calcium oxide in the slag and the matrix composition. However, the existence of the zircon phase in the C4 sample showed that the zirconia can react with the SiO2, leads to a lower temperature phase, and improve the corrosion resistance.

Southern Africa hosts some of the largest manganese reserve in the world. The production of manganese alloys is of strategic importance to the economies of the region. The submerged arc furnace has become the equipment of choice to produce manganese ferro-alloy both locally and internationally. Furnace operators aim to reduce the cost of production by better understanding the role played by the various raw materials involved in the processes. Coke is one of the key raw materials fed into the SAF, it plays three key roles in electric furnaces. Coke is a reducing agent; it is a source of carbon found in the alloy; and it also acts as a resistive element facilitating heat generation in the electric furnace. The heat generated plays two key functions in the furnace; ensuring both the metal and the slag have sufficient viscosity and it provides the heat required to support endothermic reactions. This study investigated ambient temperature and high temperature resistivity characteristics of coke made from single source coals. Measurement of coke resistivity was performed using the four-point technique. The results showed a statistically significant difference of mean resistivity between coke. It was observed that coke resistivity generally decreased with increasing temperatures. Raman spectroscopy was used to showed that the structural order of coke changes with increasing temperature.

In the tapping process of electric arc furnace, aluminium is usually charged into the ladle to remove the oxygen, which increased the cost and reduced steel cleanliness. Recently, a new technology ...

Abstract The state of the art for the recovery of metals from steel industry by-products using hydrometallurgical processes is reviewed. The steel by-products are different slags, dusts, and sludges from a blast furnace (BF), basic oxygen furnace (BOF), electric arc furnace (EAF), and sinter plant, as well as oily mill scale and pickling sludge. The review highlights that dusts and sludges are harder to valorize than slags, while the internal recycling of dusts and sludges in steelmaking is inhibited by their high zinc content. Although the objectives of treating BF sludges, BOF sludges, and EAF dust are similar, i.e., the removal of zinc and the generation of an Fe-rich residue to be returned to the steel plant, these three classes of by-products have specific mineralogical compositions and zinc contents. Because wide variations in the mineralogical composition and zinc content occur, it is impossible to develop a one-size-fits-all flow sheet with a fixed set of process conditions. The reason for the interest in EAF dust is its high zinc content, by far the highest of all steel by-products. However, EAF dust is usually studied from the perspective of the zinc industry. There are not only different concentrations of zinc, but also variations in the all-important ZnO/ZnFe2O4 (zincite-to-franklinite) ratio. In many chemical processes, only the ZnO dissolves, while the ZnFe2O4 is too refractory and reports to the residue. It only dissolves in concentrated acids, or if the dust is pre-treated, e.g., with a reductive roasting step. The dissolution of ZnFe2O4 in acidic solutions also brings significant amounts of iron in solution. Finally, due to its high potassium chloride content, sinter-plant dust could be a source of potassium for the fertilizer industry. Graphical Abstract

Recently geopolymer technology possesses not only great efficiency in immobilizing heavy metal wastes but also produces valuable materials that can be applied in building sectors. The aim of this study is to examine the capability of geopolymers in the immobilization and entrapping of heavy metals bearing materials. The study will focus on the evaluation of optimum ratio of heavy metal that can affect and densify the produced composite. The studied mortar’s binder was made from blast furnace slag, while the used fine aggregates were air-cooled slag

The effect of CaF2 addition on dephosphorization reaction between molten steel and electric arc furnace (EAF) slag using direct reduced iron (DRI) at 1823 K (1550 °C) was investigated. Basicity, the thermodynamic parameter affecting the removal capacity of phosphorus (i.e., phosphate capacity), decreased using DRI due to an increased SiO2 concentration in the slag. To minimize slag volume and maximize dephosphorization efficiency, the CaF2 was added to the slag. As CaF2 content increased (0 to 10 mass pct), dephosphorization efficiency also increased. Thermodynamic analysis in conjunction with slag structural studies using Raman spectroscopy were conducted to explain the complicated phenomena. The results exhibited that even 5 to 6 mass pct CaF2 can improve the dephosphorization efficiency when DRI is used as raw material in an EAF process.

The chemical and phase transformations in the the weltzslag ‒ carbon system in the range 1700‒2100 K and a pressure of 0,1 MPa were simulated. It was found that the maximum degree of transition of iron to condensed Fe 3 Si is from 34,7 % at 1800 K to 99,9 % at 2100 K, and to the Fe 5 Si 3 compound from 47,7 % at 1900 K to 45,6 % at 2000 K. as the temperature rises, iron begins to move into the gas phase. Silicon, in comparison with iron, is more difficult to recover and, as the temperature rises, begins to pass into the gas phase. The degree of transition of nonferrous metals Zn, Cd and Pb to the gas phase is 99,99 % over the entire temperature range. Modeling made it possible to analyze the possibility of obtaining ferrosilicon from technogenic non-ferrous metallurgy wastes by the method of electric melting in an electric arc furnace.

The effect of using an iron metal collector (MC) instead of copper on the degree of extraction of platinum, palladium, and rhodium is investigated in processing ceramic-based automotive catalysts in an electric arc furnace. The dependence of the effect of melt holding time on platinum group metal (PGM) deposition rate on a furnace hearth is analyzed. It is determined that during creation of a homogeneous mixture and introducing a metal collector (MС) into the catalyst composition effective Pt, Pd, Rh extraction occurs in the first 20 minutes of melt exposure. In spite of the twice as high density of platinum, the degree of its extraction is at the level for Pd and Rh, which points to the possibility of depositing platinum group metals (PGM) on the furnace hearth using the surface of coarser added MС powder. Testing of various methods for adding MС demonstrate the effectiveness of introduction to the melt surface. When a melt is heated above the melting temperature of platinum and palladium, the maximum degree of extraction is reached in 6 min. This shows that solid rhodium may passivate the surface of added MС. In order to create conditions when there is always an MС free surface to which solid rhodium may adhere, the rate coefficient is determined for effective dissolution of Rh in iron MС. Determination of this coefficient makes it possible to scale up results of laboratory studies and to predict the minimum time required for melting MС on the furnace hearth without loss of valuable component.

Chemical and phase transformations in aWaelz process-slag – carbon system in the range 1700 – 2100 K at a pressure of 0.1 MPa are modeled. It is established that the maximum degree of iron transferred into condensed Fe3 Si is from 34.7 % at 1800 K to 99.9 % at 2100 K, and into Fe5Si3 from 47.7% at 1900 K to 45.6% at 2000 K. With a further increase in temperature iron starts to be transferred into the gas phase. Silicon, in comparison with iron, is more difficult to recover and with an increase in temperature starts to pass into the gas phase. The degree of nonferrous metal Zn, Cd and Pb transfer into the gas phase is 99.99 % over the whole temperature range. Modeling makes it possible to analyze the possibility of obtaining ferrosilicon from technogenic non-ferrous metallurgy waste by electric melting in an electric arc furnace.

The method of carbon powder mixed injection with a shrouding supersonic oxygen jet was proposed to increase the utilization efficiency of carbon powder and improve the foaming slag operation during the electric arc furnace (EAF) steelmaking process by delivering the carbon powder more deeply into the molten bath. In this study, the fluid flow characteristics of the carbon powder mixed injection with a shrouding supersonic oxygen jet were studied and analyzed using numerical simulations, which were first validated by a cold test experiment. Compared with the conventional carbon powder injection without a shrouding jet, the shrouding supersonic oxygen jet can protect the central gas-powder jet against the entrainment of the surrounding atmosphere, increase the velocity of carbon powder and make the carbon powder cluster together in a longer distance. Furthermore, the industrial application research was carried out in a 50-ton commercial Consteel EAF, and the relative metallurgical effects were also studied. Compared with EAF steelmaking using conventional carbon powder injection without a shrouding jet, the powder consumption, tap-to-tap time, FeO content in the final molten slag and phosphorus content of the final molten steel were reduced by 19.3 kWh/ton, 4 min/heat, 2.6 pct and 1.2 × 10−3 pct, respectively, after using the method of carbon powder mixed injection with a shrouding supersonic oxygen jet.

Manganese alloys are important raw materials for steelmaking. However, selective mining of high-grade manganese ore resources has resulted in a scarcity of these high-grade Mn ores (Mn: >42; Mn/Fe: >5). The present research work is carried out to explore a new smelting reduction process to produce high-Mn/Fe synthetic Mn ore from low-grade ferruginous manganese ores. Representative samples of low-grade ores (Mn: 25–30%; Mn/Fe: ~1) were collected and smelting reduction studies were carried out using variable smelting power (20–30 kWh), carbon rate (10–20% of ore) and slag basicity (0.1–0.3) to produce high-MnO slag and manganese pig iron. Studies have shown that different-grade high-MnO slags (MnO: 38.57–58.24%; Mn/Fe: >15) and manganese pigs (Mn: 5.16–24%) can be produced at optimum process conditions. The high-MnO slag can be used as synthetic ore for the ferroalloy production process. The developed process is capable to effectively segregate the iron and manganese in the metal and slag, respectively. The optimum Mn and Fe separation (>95%) was achieved by smelting of 10 kg Mn ore batch in a 50-kVA electric arc furnace using 30 kWh smelting power and 0.16 kg of coke. The slag basicity was maintained at 0.3 and the optimum slag SiO2 was ~30%. The studies indicated that the upgrading of low-grade ferruginous manganese ores is a promising solution for achieving high-Mn/Fe-ratio synthetic ores for ferroalloy production. It can help the manganese alloy industry to overcome challenges associated with the scarcity of high-Mn/Fe-ratio Mn ores and efficient utilization of low-grade resources.

Pure metal-doped (Cu,Zn)Fe2O4 was synthesized from Zn-containing electric arc furnace dust (EAFD) by solid-state reaction using copper salt as additive. The effects of pretreated EAFD-to-Cu2(OH)2CO3·6H2O mass ratio, calcination time, and calcination temperature on the structure and catalytic ability were systematically studied. Under the optimum conditions, the decolorization efficiency and total organic carbon (TOC) removal efficiency of the as-prepared ferrite for treating a Rhodamine B solution were approximately 90.0% and 45.0%, respectively, and the decolorization efficiency remained 83.0% after five recycles, suggesting that the as-prepared (Cu,Zn)Fe2O4 was an efficient heterogeneous Fenton-like catalyst with high stability. The high catalytic activity mainly depended on the synergistic effect of iron and copper ions occupying octahedral positions. More importantly, the toxicity characteristic leaching procedure (TCLP) analysis illustrated that the toxic Zn-containing EAFD was transformed into harmless (Cu,Zn)Fe2O4 and that the concentrations of toxic ions in the degraded solution were all lower than the national emission standard (GB/31574—2015), further confirming that the as obtained sample is an environment-friendly heterogeneous Fenton-like catalyst.

Ti-stabilized 321 stainless steel was prepared using an electric arc furnace, argon oxygen decarburization (AOD) furnace, ladle furnace (LF), and continuous casting processes. In addition, the effect of refining process and utilization of different slags on the evolution of inclusions, titanium yield, and oxygen content was systematically investigated by experimental and thermodynamic analysis. The results reveal that the total oxygen content (TO) and inclusion density decreased during the refining process. The spherical CaO–SiO2–Al2O3–MgO inclusions existed in the 321 stainless steel after the AOD process. Moreover, prior to the Ti addition, the spherical CaO–Al2O3–MgO–SiO2 inclusions were observed during LF refining process. However, Ti addition resulted in multilayer CaO–Al2O3–MgO–TiOx inclusions. Two different samples were prepared by conventional CaO–Al2O3-based slag (Heat-1) and TiO2-rich CaO–Al2O3-based slag (Heat-2). The statistical analysis revealed that the density of inclusions and the TiOx content in CaO–Al2O3–MgO–TiOx inclusions found in Heat-2 sample are much lower than those in the Heat-1 sample. Furthermore, the TO content and Ti yield during the LF refining process were controlled by using TiO2-rich calcium aluminate synthetic slag. These results were consistent with the ion–molecule coexistence theory and FactSage™7.2 software calculations. When TiO2-rich CaO–Al2O3-based slag was used, the TiO2 activity of the slag increased, and the equilibrium oxygen content significantly decreased from the AOD to LF processes. Therefore, the higher TiO2 activity of slag and lower equilibrium oxygen content suppressed the undesirable reactions between Ti and O.

Electric arc furnace (EAF) slag aggregate, a waste by-product of the steel industry, exhibited a high potential for phosphorus (P) removal and had attracted considerable attention. The main objectives of this study were to evaluate the performance of using EAF slag aggregate as an adsorbent for P removal and identify its P removal capacity. A series of batch tests showed that P removal capacity of EAF slag increases gradually with the increase of pH with a range of 2-10, while the highest P removal capacity (1.94 mg/g) can be obtained at pH 12. The adsorption kinetics of P on EAF slag can be described by pseudo-second-order kinetic equations. Isothermal adsorption simulations showed that the best fitted model was the Freundlich model with a correlation coefficient of 0.9825. A continuous flow column experiment feeding a synthetic influent containing 15 mg P/L was operated for 60 days and the P removal efficiency was greater than 95% with a P removal capacity of 1.6 mg P/g slag. The results obtained in this study showed that EAF slag could act as an efficient adsorbent for P removal. Calcium phosphate precipitation depends on the release of Ca

Low-carbon ferromanganese (LC-FeMn) is an essential ingredient for making high-strength low-alloy steel and stainless steel. The conventional industrial-scale silicothermic method for the production of LC-FeMn comprises several energy intensive complex steps consuming about 2000 kWh/ton. We have attempted an improved silicothermic process, which is based on a single step smelting of optimized charge mix in the electric arc furnace. Thermochemical simulation of the smelting process by FactSage 6.4 showed significant effect of the charge mix basicity (B = CaO/SiO2) on manganese, iron, silicon and phosphorous distribution between the metal and slag. The optimum basicity was found to be 1.5 at the charge mix ratio i.e., Mn ore/lime/SiMn of 1:1:0.6 in the smelting tests. Under optimum conditions, the energy consumption was about 690 kWh/ton. This approach has potential benefits for the ferromanganese industry in terms of simpler and energy efficient process.

Indonesia coal ash is predicted to reach 10.8 million tons in the year 2020 but its utilization is still limited. In the last decade, coal ash has become a promising REY source candidate. To determine the potency of REY in Indonesia coal ash, information about element concentration and mineralogy of the ash is essential. In this study, coal ash samples were taken from Paiton-2, Pacitan, Rembang, and Tanjung Jati coal-fired power plants. Element content and mineralogy were analyzed using Inductive Couple Plasma Mass Spectroscopy/Atomic Emission Spectroscopy (ICP-MS/AES), X-Ray Diffractometer (XRD) and petrographic. The results showed that coal fly ash and bottom ash contains critical REY in the range of 38% to 41% with Coutlook larger than one. XRD analysis showed that both fly ash and bottom ash have similar mineral phases with slightly different concentrations. The mineral phase is dominated by amorphous glass, quartz, Fe-bearing minerals, and unburned carbon. The amorphous glass phase in fly ash is in the range of 23 to 34% while in bottom ash between 14 and 34%. Unburned carbon content in fly ash and bottom ashes are 7-13% and 7-19%, respectively. Fe-bearing mineral content in fly ash is 15-20% and bottom ash is 13-20%. In addition, Indonesia coal ash has a higher Heavy-REY enrichment factor than Light-REY. The Enrichment Factor of HREY in fly ash is as much as 1.3 times (in average) of the bottom ash.

The article contains sections titled: 1. Introduction 2. Properties 3. Occurrence 3.1. Minerals 3.2. Deposits 4. Production 4.1. Concentration 4.2. Processing of Concentrate 4.3. Recovery from Spent Petroleum Catalysts 4.4. Recovery during Production of Tungsten Ores 4.5. Production of Molybdenum Metal Powder 4.6. Production of Compact Molybdenum Metal 4.7. Processing of Molybdenum 4.8. Molybdenum-Base Alloys 5. Uses 6. Production of Ferromolybdenum 6.1. Ferromolybdenum Grades 6.2. Raw Materials 6.3. Submerged Arc Furnace Carbothermic Reduction 6.4. Metallothermic Reduction 7. Molybdenum Compounds 7.1. Overview of Molybdenum Chemistry 7.2. Molybdenum Oxides 7.3. Molybdenum Chalcogenides 7.4. Molybdenum Halides 7.5. Molybdates, Isopolymolybdates, and Heteropolymolybdates 7.6. Other Molybdenum Compounds 8. Uses of Molybdenum Compounds 8.1. Catalysis 8.2. Lubrication 8.3. Corrosion Inhibition 8.4. Flame Retardancy and Smoke Suppression 8.5. Pigments 8.6. Agriculture 9. Analysis 10. Economic Aspects 11. Environmental Aspects 12. Toxicology and Occupational Health

The recovery of iron from Electric Arc Furnace (EAF) smelter slags via hydrochloric acid leaching and solvent extraction was investigated with a view to developing a simple hydrometallurgical route...

Improvements to the wear performance of CD4MCu (a cast Fe-Cr-Ni-Cu-Mo duplex stainless steel grade) would be of great benefit in pump applications. This study demonstrates that CD4MCu stainless steels reinforced with (Nb0.75,Ti0.25)C particles can be fabricated by simply melting the elements required for the CD4MCu stainless steel together with the amounts of Nb, Ti and C required to achieve a specific volume fraction of (Nb0.75,Ti0.25)C particles in a miniature laboratory argon arc furnace. Their potential as erosion resistant materials was evaluated through microstructural characterization, hardness testing, and sliding wear tests. The formation of (Nb0.75,Ti0.25)C particles was found to improve the bulk hardness of the CD4MCu stainless steels without significantly altering its duplex microstructure, which then led to better wear performance. The results indicate that large-scale casting of the proposed materials should be possible and that they have potential as erosion resistant materials.