Metallurgical Dust Research Articles

Hydrothermal precipitation of copper from leaching solutions of metallurgical dusts

In this work, we aim to establish the main regularities of hydrothermal precipitation of copper from the previously unstudied sulfuric-nitric acid and sulfate solutions of atmospheric and autoclave processing of metallurgical dusts. Pyrite was used as a sulfidizer. The elemental composition of the products was determined by X-ray fluorescence, inductively coupled plasma atomic emission spectrometry, and atomic absorption analysis. It was found that copper precipitation by the proposed technology enables its recovery at a level of more than 95%. For sulfate solutions with a high arsenic concentration, a two-stage scheme of oxidation-hydrothermal treatment with the following parameters was proposed: temperature 180°С, duration 2 h, oxygen consumption 0.026 dm3/g pyrite (for the 1st stage), and 200°С and 2 h (for the 2nd stage). Extraction in the cake amounted to 95.4% of copper (in the form of Cu2S) and 91.4% of arsenic (in the form of FeAsO4), which allowed further separation of these metals by flotation. An autoclave treatment of a Cu–Zn–Fe–As–NO3 solution in the presence of pyrite at 180–220°С produced the activation energy values (kJ/mol) corresponding to the kinetic regime calculated by the two methods: 64.6 by the conventional method and 60.5 by the shrinking core model. The kinetic parameters of CuSO4–H2SO4–FeS2–H2O and CuNO3–H2SO4–FeS2–H2O systems were also determined. Flotation enrichment of copper autoclave precipitation cake was shown to result in a high degree of Cu and As separation, with the recovery amounting to Cu ˃ 95% and As ˂ 5%. Precious metals contained in pyrite are transferred to a flotation concentrate by 92.7% (Au) and 96.5% (Ag). The composition of the resulting flotation concentrate comprised (%): 12 Cu; 37 Fe; 38 S; 13 other elements. It is shown that, in order to obtain a product with the required content of copper, flotation concentrate should be separated into pyrite and copper concentrates followed by an additional flotation of primary copper concentrate in an alkaline medium in the presence of lime. Hence, our study has established the main regularities of hydrothermal precipitation of copper from the sulfuric-nitric acid and sulfate solutions of atmospheric and autoclave processing of metallurgical dusts.

Substitution of blast furnace slag by melting furnace slag as active component in green concrete application

Blast furnace slag (BFS), a commonly used substitute for cement clinker, is in large demand and gradually increasing in price. Melting furnace slag (MFS), a by-product of the co-disposal of waste incineration fly ash and metallurgical dust sludge, has potential hydration properties, and its large accumulation also poses a serious threat to the environment. In this study, we focus on the effect of MFS replacing BFS on concrete properties and its hydration mechanism. Results showed that MFS significantly enhanced the compressive strength at the later stage of hydration, and the 28-d compressive strength of MSD concrete was 15.15 % higher than BSD concrete. MFS enriched with a large amount of amorphous silica and alumina played a key role in the hydration process. This is mainly shown as the increase in the fluctuation of Si-O and Al-O bond strengths and the decrease in the energy separation between Ca 2p and Si 2p levels. In addition, the increased substitution of aluminum for silicon in MSD results in the formation of C-A-S-H gels, which are tightly bonded with ettringite to form a composite structure. Subsequent durability assessments indicate that the incorporation of MFS diminishes the permeability to chlorides and sulfates, while also bolstering the concrete’s resistance to carbonation. These findings imply a positive impact on the concrete’s enduring service life.

Evaluation of steel metallurgical dust management: combining treatment methods and resource attributes

The escalating challenges of resource scarcity and environmental pressures have drawn significant attention to heavy metal-containing dust generated during steel production. While previous research on heavy metals in steel manufacturing has primarily focused on emission inventories, health and ecological risks, and recycling technologies, the assessment of steel metallurgical dust management has been largely overlooked. To address this research gap, this study employed statistical entropy analysis to evaluate the effectiveness of dust treatment in the steel production process, aiming to identify potential issues in dust management. Furthermore, an evaluation framework was established to systematically assess the resource attributes of steel metallurgical dust, thereby supporting evidence-based decision-making in dust management. Results indicate that Cd, Pb, As, Zn, Cr, and Hg tend to accumulate in dust during steel production. Given its high resource attribute, converter dust should be prioritized for recovery. Further analysis suggests that the rotary kiln process plays a transitional role in dust recovery. This study provides a scientific foundation for dust management in the steel industry and offers guidance for the sustainable development of dust utilization.

Study on the reaction mechanism of multi-source metallurgical dust for zinc extraction and iron enrichment

Multi-source metallurgical dust can realize the purpose of zinc extraction and iron enrichment by high-temperature reduction. In this paper, based on the zinc extraction and iron enrichment from multi-source metallurgical dust in rotary kiln process, thermodynamic calculations and reduction kinetic experiments were carried out to clarify the thermodynamic conditions and kinetic limiting factors of the reduction of Fe-Zn-C-O system of metallurgical dust, and to obtain the suitable parameters of reduction temperature and reaction time, etc. The results showed that Fe mainly existed in the form of Fe2O3 and Fe3O4 in metallurgical dust. Zn mainly existed in the form of ZnO and ZnFe2O4, with a small amount existed in ZnS. The starting temperatures of the reduction of ZnO, ZnFe2O4, ZnS with C were 951.09 °C, 581.55 °C and 1862.44 °C, respectively. Combined with the temperature of the smelting condition of rotary kiln, it was known that the presence of ZnS was the key factor leading to the limitation of zinc removal rate. ZnO and ZnFe2O4 showed higher reduction difficulty compared to iron oxides, so the metallization rate of rotary kiln slag could be improved by controlling the smelting atmosphere. The weight loss rate, metallization rate and dezincification rate of multi-source metallurgical dust showed an increasing trend with the change of temperature and time, and the more desirable effect of weight loss rate, metallization rate and dezincification rate were 46.7%, 87.1%, and 92.5% under laboratory conditions at reduction temperature 1100 °C and reaction time 50 min.

Denitrification characteristics and reaction mechanism of Ce-doped Fe-based catalysts from modified metallurgical dust containing iron

Denitrification characteristics and reaction mechanism of Ce-doped Fe-based catalysts from modified metallurgical dust containing iron

Recycling of iron-rich basic oxygen furnace dust using hydrogen-based direct reduction

The reduction of iron oxide-bearing ores necessitates the exploration of alternatives. Recycling iron oxide-enriched metallurgical dust could serve as secondary raw material for metallurgical processes. Implementing environmentally friendly technologies utilizing hydrogen has prompted the concept of hydrogen reduction of metallurgical dust to recycle secondary steel production products. The present study investigates the characteristics of hydrogen reduction of briquettes and pellets produced from basic oxygen furnace dust and reduced at the temperature of 850 °C. Experimental results revealed that the reduction degree for pellets was approximately 1.5 times higher compared to briquettes. The reduction swelling index of pellets was noticeable lower compared to literature data of reduction swelling index for iron ore pellets. Scanning electron microscopy/energy-dispersive X-ray spectroscopy was carried out to detect changes in the microstructure and chemical composition of the samples. Subsequent melting of the reduced samples unveiled non-metallic inclusions within the iron alloy and the impact of slag on their distribution between the alloy and slag.

Sewage sludge enhances cold-pressed pelletization and carbothermic reduction of steel plant sintering dust

The sludge-based forming thermal reduction can be used to improve the resource utilization ability of sintering dust. This paper discussed the feasibility and mechanism of sewage sludge as a binder and reducing agent to facilitate iron recycling from sintering dust by mixing wet sludge to form and adding dry sludge to reduce. The results showed that a 1.4% ratio of sewage sludge significantly enhanced the strength of metallurgical pellets, and the compressive strength of wet and dry pellets reached 309.5 and 1233.5 N/P. Meanwhile, with the addition of dry sludge (S/Fe = 2.0), the metallization ratio can be up to 88.4%. Sewage sludge has a more efficient reduction potential than other carbon sources as reducing agents. Combined with XRD, XPS, TG-MS, TG-FTIR, and other characterization methods, the reduction phenomenon of iron was confirmed, and the migration and transformation of metals in sintering dust and the segmented volatilization rule of Pb, Zn, K, Na, and other elements were revealed. It is proven that sludge as the disposal route of metallurgical dust cold-pressed forming and reduction is a green and sustainable view and promising research direction.

Process and mechanism of preparing metallized blast furnace burden from metallurgical dust and sludge

Metallurgical dust and sludge are solid waste resources with recycling value. In recent years, rotary hearth furnace has become the most important means to treat metallurgical dust and sludge because of its wide range of raw materials and strong treatment capacity. In this study blast furnace ash and converter sludge were selected as the research objects, and high-quality metallized pellets were prepared based on the rotary hearth furnace process. The strength changed of pellets, the reduction process of iron oxides and the removal process of zinc during the roasting of pellets in rotary hearth furnace were studied. To explore the reasonable roasting condition for preparing metallized pellets in rotary hearth furnace. The optimum roasting temperature of the pellets was 1250℃ and the roasting time was 25 min. The compressive strength, metallization rate and dezincification rate of metallized pellets reached 1361N, 97.44% and 95.67%, respectively. The efficient resource utilization of various metallurgical dust and sludge is realized.

Waste control by waste: Extraction of valuable metals from mixed metallurgical dust by boiling furnace roasting

Electric arc furnace dust (EAFD) is a hazardous waste by-product generated during the process of electric furnace steelmaking, which is rich in valuable metal elements. In order to solve the problem of environmental pollution and resource utilization of EAFD, we propose a new process for medium-temperature suspension roasting EAFD and coke dry quenching dust to extract valuable metals. The thermodynamic properties and migration behavior of valuable elements involved in the reaction were analyzed using thermodynamic simulation software FactSage8.1 and thermogravimetric mass spectrometry. The mechanism and kinetic equation of the dezincification process were investigated using the Kissinger method and Coats-Redfern model. The impact of various parameters on the process efficacy and ash fusion characteristics of the material were investigated through boiling furnace experiments. The results demonstrate that elevating the reaction temperature and decreasing the zinc partial pressure is more favorable for reducing and separating zinc. The corresponding kinetic equations for the decomposition of ZnFe2O4 and reduction of ZnO are denoted as dα/dT = 1.69 × 1012exp (−3.37 × 104/T) and dα/dT = 6.76 × 106 exp (−2.08 × 104/T) × (1 − α) [−ln(1 − α)]3/4, respectively. The optimum reaction temperature was 1050 °C, the C/O ratio was 0.8, the reaction time was 40 min, and the ventilation rate was 3500 mL/min. Under these conditions, the material had no liquid phase agglomeration, and the removal rates of zinc and lead were 93.38 % and 98.14 %, respectively. The crude zinc dust with a zinc grade of 87.57 % and the alloy slag with an iron grade of 52.38 % was obtained. The new process utilizes the excellent heat transfer characteristics and fluidization conditions of the boiling furnace to efficiently realize the high-grade recovery of valuable metals in the EAFD, which provides new insights for the clean treatment of zinc-containing waste.

Multi-Source Ferrous Metallurgical Dust and Sludge Recycling: Present Situation and Future Prospects

Multi-Source Ferrous Metallurgical Dust and Sludge Recycling: Present Situation and Future Prospects

Effect of different leaching solutions on removal efficiency of K, Na, and Zn elements from blast furnace bag dust

ABSTRACT As a by-product of steel production, the efficient treatment of metallurgical dust is an important research topic in metallurgical industry. To recycle blast furnace bag dust into metallurgical process, harmful elements (K, Na and Zn) need to be removed. By using different acidic solvents and leaching conditions to treat the bag dust, the best leaching conditions of K, Na and Zn elements were explored. The results show that the optimal leaching conditions of harmful elements in water solution are: 4 ml/g liquidsolid ratio, 50°C temperature, 30 min stirring time. Water solution has a certain removal effect on K and Na elements but has little effect on Zn content. The leaching rates of K, Na and Zn were improved by using ammonia, hydrochloric acid and sulfuric acid solutions. Sulfuric acid with a concentration of 2 mol/L has the best removal efficiency for K, Na and Zn elements in bag dust, and the maximum removal rates of K, Na and Zn are 82.3%, 81.5% and 88.7%, respectively. Through this study, the potential to leach K, Na and Zn elements from bag dust was demonstrated, and an experimental basis for the resource utilization of bag dust in metallurgical process was provided.

Investigation of the enrichment-purification process and electrochemical performance of kish graphite in dust from blast furnace tapping yard

Kish graphite is a typical byproduct of steel production, and its enrichment and purification are essential prerequisites for its high value and comprehensive utilization. To solve the problem of recovery and application of difficult-to-treat kish graphite with a small particle size obtained from metallurgical dust, kish graphite in blast furnace tapping yard dust was effectively enriched and purified by a comprehensive flotation-acid leaching treatment process in this study. The influence of the flotation agents on the flotation process was explored. The results showed that the optimized flotation agent dosage was 500.0 g·t−1 (collector) and 120.0 g·t−1 (frother), respectively. Based on the optimized flotation scheme, a graphite concentrate (FG) with 79.12 % carbon content and 93.5 % carbon recovery was obtained. After the leaching treatment with a HCl-HF mixed acid solution, the carbon content of the graphite concentrate increased to 95.55 %. The ID/IG value of the graphite concentrate was 0.145, and the average lattice spacing was approximately 0.3354 nm. The SEM results showed that the leaching-treated graphite concentrate (AFG) had a loose, fragment-like structure. When used as an anode material for lithium-ion batteries, The AFG still provided a high reversible capacity of ∼370 mAh·g−1 and excellent coulombic efficiency of 99.6 % after 350 cycles. In addition, an industrial-grade recycling and utilization path for kish graphite based on a circular supply chain strategy was proposed. The results of this study may serve as a conceptual basis for the recovery and application of kish graphite from metallurgical dust.

Innovative B-PA binder for enhanced cold pelletization: a sustainable strategy for utilizing iron-containing dust and sludge

A large amount of iron dust and sludge is produced in the process of iron and steel metallurgy, and its efficient utilization has important economic value and environmental significance. In this study, a method of cold-bonded aggregate is used to co-process stainless steel pickling sludge (SSPS) and gravity dust (GD). The preparation process parameters of cold-bonded pellet are optimized. The role mechanism of the binder on cold-bonded aggregates is studied, and a new type of composite binder, bentonite-plant asphalt (B-PA), is invented. The optimal ratio of bentonite to plant asphalt is determined to be 3:1. The metallurgical performance of B-PA agglomerates is tested, with results showing an RDI+3.15 at 93.6%, a RI at 79.3%, an RSI at 14.2%, a DI at 4.01%, and a thermal cracking temperature reaching 721 °C. The microstructure of the agglomerates after performance testing is characterized using XRD and SEM. This cold-bonding pelletization technology is expected to be widely used in the efficient comprehensive utilization of metallurgical dust in the future, which is of great significance for reducing costs, increasing efficiency, and promoting green environmental protection in the steel industry.

Zinc removal from metallurgical dusts with iron- and sulfur-oxidizing bacteria

The generation of currently partially recyclable metallurgical dusts during the steel production represents a challenge for the realization of a circular economy in this industrial sector. Due to a high iron concentration, the reutilization of blast furnace and cast house dusts in internal crude steel processes, is state of the art. However, heavy metal impurities such as zinc, act as an interference due to diverse negative effects. The aim of this study is to utilize Acidithiobacillus ferrooxidans, an iron- and sulfur-oxidizing bacteria, to solubilize zinc whilst retaining iron in the dust residue intended for reuse. To achieve this, the biooxidation of elemental sulfur is of crucial relevance. Two different strains of A. ferrooxidans (DSM 583 and CCM 4253) were cultivated and their leaching performances were compared to each other using a stirred tank reactor operated in a fed batch set-up, with a working volume of 3 L, at an operation temperature of 30 °C. The dust concentration was gradually increased until a maximum of 125 g/L, after which the reactors were left to run for three additional cycles to ensure replicability of results. For both strains, at a cast house dust concentration of 125 g/L paired with a leaching duration of two weeks, an average zinc removal of 56 % was achieved whereas solely an average of 4 % of iron was leached.

Valuable Recovery Technology and Resource Utilization of Chromium-Containing Metallurgical Dust and Slag: A Review

As a type of metallurgical solid waste with a significant output, chromium-containing metallurgical dust and slag are gaining increasing attention. They mainly include stainless steel dust, stainless steel slag, ferrochrome dust, and ferrochrome slag, which contain significant amounts of valuable elements, such as chromium, iron, and zinc, as well as large amounts of toxic substances, such as hexavalent chromium. Achieving the harmless and resourceful comprehensive utilization of chromium-containing metallurgical dust and slag is of great significance to ensuring environmental safety and the sustainable development of resources. This paper outlines the physicochemical properties of stainless steel dust, stainless steel slag, ferrochrome dust, and ferrochrome slag. The current treatment technologies of chromium-containing metallurgical dust and slag by hydrometallurgy, the pyrometallurgical process, and the stabilization/solidification process are introduced. Moreover, the comprehensive utilization of resources of chromium-containing metallurgical dust and slag in the preparation processes of construction materials, glass ceramics, and refractories is elaborated. The aim of this paper is to provide guidance for exploring effective technology to solve the problem of chromium-containing metallurgical dust and slag.

Bioleaching of Zinc from Blast Furnace Cast House Dust

Metallurgical dusts are by-products from steel manufacturing. The high iron content of cast house dust (~64%) makes this by-product an interesting iron feedstock alternative. Therefore, its return into the internal steelmaking circuit, specifically in the sinter plant, is a common practice in the steel industry. However, this dust fraction also contains heavy metals, as zinc. As a result of the re-entry of zinc into the process, the zinc concentration in the blast furnace flue gas dust also increases. This prevents the full recirculation of the blast furnace flue gas dust in the steelmaking process despite its relatively high iron content (~35%), thus causing part of the blast furnace flue gas dust to end in the landfill. The goal of this study was to investigate the usage of bacteria, such as the sulfur oxidizing Acidithiobacillus thiooxidans or the iron and sulfur oxidizing Acidithiobacillus ferrooxidans, to leach the undesirable element zinc from the cast house dust while preventing the leaching of iron, by adjusting the sulfur addition and avoiding, at the same time, the accumulation of sulfur in the solid fraction. Experiments proved that a co-culture of A. thiooxidans and A. ferrooxidans can effectively leach zinc from metallurgical dusts, maintaining high iron concentrations in the material. The influence of elemental sulfur on the efficiencies reached was shown, since higher removal efficiencies were achieved with increasing sulfur concentrations. Maximum zinc leaching efficiencies of ~63% (w/w) and an iron enrichment of ~7% (w/w) in the remaining residue were achieved with sulfur concentrations of 15 g/L for cast house gas concentrations of 125 g/L.

EXAMINATION OF NEW GROWTHS IN MODIFIED SULFATE-BASED COMPOSITES BY SCANNING ELECTRON MICROSCOPY

The structure of a gypsum matrix, which is characterized by the size, shape, and morphology of crystals, the state of the interfacial surface, and the number and strength of contacts between new growths, determines the basic physical and technical properties of materials. The effect of various modifiers, mainly of technogenic origin, on the gypsum stone structure has been examined by scanning electron microscopy and energy-dispersive X-ray analysis. In the study, building gypsum and metallurgical dust, granulated blast furnace slag, and siltstone mineral modifiers have been used. It has been established that the introduction of modifiers improves the physical and mechanical properties of a binder. This is probably due to the fact that the additives act as crystallization centers during the matrix structure formation and facilitate filling of the stone pore space.

Zn Extraction from Zinc-Containing Sludge Using Ultrasonic Treatment Leaching with ChCl-MA DES

The recovery of zinc from metallurgical dust sludge is a crucial component of using solid waste as a resource in the metallurgical process, and deep eutectic solvent–ultrasonic synergistic enhanced leaching is an efficient method of doing so with excellent economic effects. The leaching rate of zinc is used as the value of response in this study, along with the four process conditions of leaching temperature, leaching time, liquid–solid ratio, and ultrasonic power. By building a regression model, the relationship between the various parameter components is investigated, and a strategy for optimization is then chosen and confirmed. The findings indicate that, for the parameters of temperature 40 °C, ultrasonic power 90 W, liquid–solid ratio 7:1 g/L, stirring speed 250 rpm, and leaching duration 80 min, the prediction value of the regression model of the zinc leaching rate is 98.47%. The average zinc leaching rate obtained by the 3 parallel verification experiments was 98.49%; the deviation from the regression model’s predicted value was 0.02%. This demonstrated that the experimental results were consistent with those predicted by the regression model, the experimental results were reliable and trustworthy, and the optimization scheme was reasonable and accurate. Compared with the conventional leaching method (leaching rate: 91.61%), the method under ultrasound increased the zinc leaching rate by 6.88%.

Synergistic reaction behavior of pyrolysis and reduction of briquette prepared by weakly caking coal and metallurgical dust

Synergistic reaction behavior of pyrolysis and reduction of briquette prepared by weakly caking coal and metallurgical dust

Preparation of Micro-Electrolytic Iron-Carbon Filler for Sewage by Recycling Metallurgical Dust

In this paper, a new iron-carbon micro-electrolytic filler for wastewater treatment was prepared using the blast furnace dust. The effects of preparation conditions on the performance of the filler during the wastewater treatment were investigated. The optimal preparation conditions of the filler were obtained, which provided an experimental theoretical basis for the use of metallurgical dust sludge in the preparation of micro-electrolytic fillers. From the results of treating methyl orange-simulated wastewater with fillers of different preparation conditions, it could be obtained that the improvement of the filler processing performance requires a suitable iron to carbon ratio, sintering time, and sintering temperature. The optimum preparation conditions were a 1:2 iron-carbon ratio, 30 min sintering time, and 1100 °C sintering temperature. The effect of treatment conditions on the performance of the iron-carbon micro-electrolytic filler was also investigated. The results showed that increasing the filler addition, increasing the treatment temperature, and decreasing the initial pH could effectively improve the treatment efficiency of the filler for methyl orange-simulated wastewater. More than 99% of the methyl orange could be removed in the wastewater under the conditions of 5 g of filler, 40 °C, and pH = 3.