Copper Smelting Slag Research Articles

Eco-friendly iron extraction from fe-containing copper smelting slag via reduction roasting with coal and magnetic separation: Experimental and mechanism insights

Copper smelting slag (CSS) is a byproduct produced during the thermal smelting of copper and poses a considerable environmental challenge, particularly in China, where its accumulated volume surpasses 1.8 billion tons. This study utilized the response surface method (RSM) to optimize experimental procedures and reduce costs, the results showed that the effects of each factor on iron recovery were in the following order: roasting temperature > roasting time > coke dosage. The optimized iron recovery of iron extraction from CSS by Magnetization-roasting reached 78.87 %, while the actual iron recovery was 78.84 %. The relative error is very small, indicating that the model is effective. Conducted the thermodynamic computational analysis to understand the migration of metal phases in CSS, employed XPS analysis to identify valence changes in key elements, and the clever combination of restricted reduction kinetics and SEM-EDS analysis shows that the reduction reaction of CSS is mainly controlled by interfacial chemistry and carbon gasification at low temperatures. By processing CSS, the study successfully produced environmentally friendly iron that can be recycled, offering a sustainable solution for managing toxic waste from copper production.

Flash sintering mechanism in multiphase materials system of copper smelting slags

Flash sintering (FS) is of great interest today, as it allows the production of high-density ceramics in seconds at lower temperatures than conventional sintering. In this study, the effects of conventional sintering at 1250°C for 4 h and FS at various electric fields (12.5, 25, 50 and 75 V/mm) on copper smelting slag (CSS), which is a multiphase material system, are investigated. The results show that FS occurs at substantially lower temperatures with much shorter times than conventional sintering, in conjunction with improved density and hardness values for CSS. The optimum condition for better densification is observed for the sample applied the 25 V/mm electric field in 554 s, and the maximum power density of about 76.49 mW/mm3. On the other hand, the shortest FS duration is achieved with the sample applied 75 V/mm in 114 s. Flash sintering at lower temperatures also stabilizedthe magnetite-hematite the phase transition, which arouses at higher temperatures. Overall, FS has made a huge contribution to reducing sintering time and temperature while providing better microstructure integrity and mechanical properties in multiphase materials systems.

Practical experience to theoretical innovation: A model for recovering metal resources from industrial solid waste − A case study of copper smelting slag

Industrial solid waste (ISW), a byproduct of modern industrial production, poses significant challenges to sustainable development due to limitations in economic and technical capabilities. Despite containing valuable metal resources, the lack of a coherent approach to its treatment has hindered progress in addressing this longstanding issue. In response, we introduce an innovative model for metal resource recovery from ISW (ISWMRR), with a specific focus on copper smelting slag (CSS) as a prevalent example. This study underscores the efficacy of mineral phase reconstruction technology in converting CSS from a liability to an asset, thereby ensuring a sustainable stream of high-quality raw materials for green steel production amid declining iron ore reserves. Experimental findings indicated that employing the ISWMRR model enabled the successful production of iron products from CSS, yielding an iron concentrate with a TFe (total iron) fraction of 87.21 wt% and iron recovery of 91.24%. This approach facilitated the cost-effective, environmentally friendly, and efficient recovery of iron resources from CSS. By furnishing a novel theoretical framework, our research seeks to guide scientists and industry stakeholders engaged in ISW management.

Boosting peroxymonosulfate activation via Fe–Cu bimetallic hollow nanoreactor derived from copper smelting slag for efficient degradation of organics: The dual role of Cu

Valorization of iron-rich metallurgical slags in the construction of Fenton-like catalysts has an appealing potential from the perspective of sustainable development. For the first time, copper smelting slag (CSS) was utilized as the precursor to synthesize hollow sea urchin-like Fe–Cu nanoreactors (Cu1.5Fe1Si) to activate peroxymonosulfate (PMS) for chlortetracycline hydrochloride (CTC) degradation. The hyper-channels and nano-sized cavities were formed in the catalysts owing to the induction and modification of Cu, not only promoting the in-situ growth of silicates and the formation of cavities due to the etching of SiO2 microspheres, but also resulting the generation of nanotubes through the distortion and rotation of the nanosheets. It was found that 100 % CTC degradation rate can be achieved within 10 min for Cu1.5Fe1Si, 75 times higher than that of Cu0Fe1Si (0.0024 up to 0.18 M−1‧min−1). The unique nanoconfined microenvironment structure could enrich reactants in the catalyst cavities, prolong the residence time of molecules, and increase the utilization efficiency of active species. Density functional theory (DFT) calculations show that Cu1.5Fe1Si has strong adsorption energy and excellent electron transport capacity for PMS, and Fe-Fe sites are mainly responsible for the activation of PMS, while Cu assists in accelerating the Fe(II)/Fe(Ⅲ) cycle and promotes the catalytic efficiency. The excellent mineralization rate (83.32 % within 10 min) and efficient treatment of CTC in consecutive trials corroborated the high activity and stability of the Cu1.5Fe1Si. This work provides a new idea for the rational design of solid waste-based eco-friendly functional materials, aiming at consolidating their practical application in advanced wastewater treatment.

Green leaching and predictive model for copper recovery from waste smelting slag with choline chloride-based deep eutectic solvent

This research was performed to investigate the optimization of copper recovery from copper smelting slag (CSS) with a deep eutectic solvent as green reagent. The effect of important parameters on leaching efficiency of copper and zinc (as well as dissolution of iron), such as leaching time, leaching temperature, liquid/solid ratio, and particle size was studied. In order to model the copper recovery, an optimization method was used. According to the chemical analysis of CSS, the slag contains 0.9% copper, 3.3% zinc, and 36.7% iron. Also, it was found that the CSS is mainly composed of Fe2SiO4, Fe3O4, and SiO2. Copper-containing structures were determined as CuO and CuS. As a result of leaching experiments, 80% copper and 61% zinc recoveries were obtained at 48 h, 95 °C, 1/25 g·ml–1, and -33 μm. It is noted that the iron and silicon dissolution remained negligible under the selected conditions. According to the mathematical model, the highest copper leaching efficiency (up to 100%) could get under optimum working conditions as 48.5 °C leaching temperature, 40.1 hours leaching duration, and 62.3 ml·g–1 liquid/solid ratio. Also, the proposed model revealed that wide range of experimental levels can be used as leaching parameter to get desired metal leaching efficiency.

Kinetics analysis of copper extraction from copper smelting slag by sulfuric acid oxidation leaching

Copper smelting slag (CSS) is generally produced from the pyrometallurgy of copper sulfide concentrate, the current storage disposal methods of CSS not only occupy precious land and pollute the environment, but also waste resources. To recover copper from the CSS and explore the atmospheric pressure oxidative leaching kinetics of copper extraction from CSS with sulfuric acid was investigated intensively. In this study, the effect of particle size, sulfuric acid concentration, temperature, liquid-to-solid ratio, and hydrogen peroxide added amount were investigated comprehensively. The results indicated that the decrease of particle size and increase of other parameters can significantly promote the leaching of copper. Under the optimum conditions, 90.7 % of the copper in the CSS was effectively leached, other copper in the leaching slag mainly existed in the form of fine-grained embedded copper sulfide. The dominant phase of the leaching slag is magnetite, which could be further recovered by conventional magnetic separation. Moreover, the kinetics of copper atmospheric pressure oxidative leaching in CSS were further expounded. The results indicated that the copper leaching kinetic conforms to the shrinking core model, and the overall leaching reaction was controlled by the internal diffusion control with an activation energy of 11.22 KJ/mol. The apparent reaction order of sulfuric acid and particle size are determined to be 0.965 and 0.478 respectively. Finally, the kinetics model equation is established for copper at normal pressure as:1-23η-1-η2/3=0.032·CH2SO40.965·r0-0.956·t. This research could provide an alternative solution for the efficient utilization of CSS.

Recovery of Cu from waste smelting slag through extraction with novel deep eutectic solvents (DESs)

ABSTRACT This study reports on the recovery of copper, zinc, and iron from the copper smelting slag (CSS) of Saindak Copper and Gold Project, Baluchistan, Pakistan using novel deep eutectic solvents (DESs) and Sulfuric acid. Sorbic acid, citric acid, and urea were each mixed with tetrabutylammonium chloride (TBAC) to prepare three DESs. Leaching experiments were performed in batch mode under a constant stirring speed of 300 revolutions per minute (rev min−1) and contact time of 2 h, under different liquid to solid ratios (L/S 1.5–3) and different temperatures (60–90°C). Results showed that the DES2 (TBAC & citric acid) recovered about 77% copper, 49% zinc, and 1% iron among other two prepared DESs at 3 L/S and 90°C. Sulphuric acid recovered 94% copper, 2% zinc, and 4.7% iron under the same conditions. The same DES also showed selectivity in the recovery of copper, as compared to iron.

Reduction of Copper Smelting Slag by Carbon for Smelting Cu-Fe Alloy

Reduction of Copper Smelting Slag by Carbon for Smelting Cu-Fe Alloy

Density Tuning in Conjunction with Pelletizing of Reductants for Enhanced Recovery from Copper Smelting Slag

Density Tuning in Conjunction with Pelletizing of Reductants for Enhanced Recovery from Copper Smelting Slag

A new eco-friendly approach for recovery of iron from copper smelting slag: Using CO2 and Cl2 recycling strategies

Copper smelting slag (CSS) is a by-product of modern copper production. In this study, iron resources were extracted from copper smelting slag using chlorine roasting and magnetic separation techniques for the first time. The results showed that hydrogen could reduce the ferrous chloride on the surface of the pellet to environmentally friendly iron, followed by the complete reduction of the ferrous chloride inside the pellet, thus increasing the metallic iron content in the roasted ore. Finally, the concentrate with a TFe (total iron) mass fraction of 73.41 wt% and iron recovery of 86.50 % was obtained, and XRF, XRD, and XPS analysis showed that iron is mainly enriched in the concentrate, and calcium, silicon, aluminum, and other elements are mainly enriched in the tailing. The innovative addition of recyclable additives in the roasting process not only reduces the production cost but also plays an important role in the current total environmental protection and environmentally sustainable development. Analytical methods such as thermodynamic evaluation, evolutionary trends of key elemental compounds, and molecular simulation were used to fully characterize the complex chemical processes of the chlorination roasting process. This study provides theoretical strategies for the cleaning of CSS and facilitates the industrial implementation of technologies for efficient and economical extraction of iron from CSS.

Snow survey within the copper ore deposits in the mining regions of the Urals

The paper presents the results of studies of dust residues of snow cover within various climatic zones and copper deposits of the Ural region. Snow cover research is one of the methods for environmental assessment of territories. This concerns the study of dust residues from snow cover samples, as shown by the example of the territories of the Northern and Southern Urals at different stages of work on copper deposits. The initial stage of study and development is considered using the example of porphyry copper deposits in the Chelyabinsk region, where snow samples reveal organic matter in dust residues, typical birch seeds, a small amount of minerals at a low dust load (P ˂ 100 kg/day per km2). For the deposits of the Ivdel region (Northern Urals), the dust residues largely contain organic dust, fragments of ore minerals (pyrite, chalcopyrite) and minerals of volcanic rocks and metasomatic rocks. The maximum value of the dust load is set for the Novo-Shemurskoye deposit currently being developed. A study of dust residues in the zone of influence of the Karabash copper smelter (before its reconstruction) has shown that in some parts of the sanitary protection zone the level of snow cover pollution is very high with dust load values up to 12,633 kg/day per km2, which is determined primarily by the widespread use of crushed copper smelting slag. In general, the study of dust residues of snow cover provides information about both the ecological state of the territories and the mineral composition of the residues, which must be used for practical purposes.

Cement from Copper smelting slag: Compressive strength, microfreeze-thaw tests and microstructural analysis

Copper smelting slag (CSS) are waste slag obtained from smelters after reusing sulphur smelting slag. This study explores the potential of CSS to serve as a resource in cement mortar construction. Specifically, the study investigates the use of mechanical and chemical methods to enhance the volcanic ash activity of CSS, enabling them to replace up to 30 % of the cement content in cement mortar. The modified CSS was analyzed in terms of particle size and (Toxicity Characteristic Leaching Procedure) TCLP testing, while cement mortar specimens were subjected to a battery of tests including compressive strength, Freeze-thaw experiment, TCLP testing and cement stability testing. The results showed that compared with the unmodified CSS material, the copper smelting slag cement material with CaCO3 meets the requirements of GB/T 1596–2017 on the standard compressive strength of OPC 42.5 grade, with a compressive strength of 38.88 MPa at 10 % CaCO3 admixture, among which the CSS cement material with 10 % CaCO3 is the best and meets the leaching toxicity standard. Moreover, the modified CSS reduced energy consumption by 7.15 %, CO2 emissions by 27.41 %, and cost by 19.84 %. XRD, FTIR and SEM analysis showed that the mechanical activation of CaCO3 doping more drastically damaged the crystal structure of CSS, and local lattice distortion occurred, which induced the transformation of CSS from crystalline phase to amorphous phase and destroyed the ordered structure of minerals, resulting in the volcanic ash activity increased. Overall, this study demonstrates that CSS can serve as a viable raw material in cement mortar samples, reducing environmental impact and achieving resourceful use of slag.

Nanocrystalline Heterostructure with Low Voltage Hysteresis for Ultrahigh-Power Sodium-Ion Capacitors

Heterostructures have garnered widespread attention for their ability to facilitate additional charge transfer, enhancing reaction kinetics and providing unprecedented effects at the interface. However, the majority of synthesized heterostructures exhibit non-uniform distribution and a scarcity of heterointerfaces, imposing significant constraints on their efficacy in sodium storage. In this study, a novel conceptualization of doping-reconstructed nanocrystalline heterostructures is introduced for the first time. Building upon this innovative concept, heterostructures characterized by uniform distribution and an abundance of heterointerfaces were successfully synthesized by reconstructing different Fe-doped Cu-based precursor into Cu2S/Cu5FeS4. Benefit by higher conductivity, a smaller sodium ion diffusion barrier, and lower voltage hysteresis, MOF-derived heterostructures maintained a capacity of 274.2 mAh g−1 after 2800 cycles at 30 A g−1. Furthermore, mineral-derived nanocrystalline heterostructures Cu2S/Cu5FeS4 (CFCS) with high tap density (3.71 g cm−3), prepared from Fe-containing copper smelting slag, exhibited a volumetric capacity 8.3 times higher than that of MOF-derived nanocrystalline heterostructures at 5.0 A g−1. The sodium-ion capacitor assembled with CFCS and activated carbon provided a high energy density of 60.1 Wh kg−1 at a high power density of 43.2 kW kg−1. This work presents a method for the controllable synthesis of uniform heterostructure with rich heterointerfaces, offering applicability.

In situ high temperature transmission electron microscopy on melting mechanism of secondary copper smelting slag

A new technique for investigations in nano-scale is applied to secondary copper smelting slag with the aim to understand melting mechanism and phase development within the material: in situ transmission electron microscopy at high temperatures. Heating the material step by step with accompanying EDX analysis allows detailed tracking of phase transformations, including changes in chemical composition. The behavior of Cu nano-spheres as well as Fe and Zn in different phases is described in detail. Evaporation of Cu, Fe and Zn is compared to available thermodynamic data, showing relatively good agreement for Cu and Fe, but different results for Zn. The observation of liquid Fe formation is a new phenomenon, which needs further investigation. High temperature transmission electron microscopy is found to be a suitable method for certain research questions, when taking limiting factors like vacuum conditions and electron beam effects into account.

Effect of As and MgO addition on arsenic vitrification in copper smelting slag

The arsenic (As) vitrification in copper smelting slag derived from the FeO−SiO2−Fe2O3−B2O3−CaO− Al2O3−(MgO) system was studied. The vitrification mechanism of As was systematically investigated by XRD, SEM, FTIR and XPS analysis. It is determined that As exhibits favorable compatibility with the iron-silicate slag. FTIR and XPS analysis indicates that As can partially substitute for silicon to form the Si—O—As structure, thereby enhancing the degree of polymerization of the melt. The [BO3]3− unit tends to decrease with the increase of the As content, while the opposite behavior is observed with the addition of MgO. Additionally, MgO increases the non-bridging oxygen (NBO) number of the melt. TCLP, SPLP and pH dependence tests show that the leaching toxicity of As increases with the increase of the As content but decreases with the addition of MgO. DSC analysis demonstrates that the incorporation of both As and MgO can improve the thermal stability of the As-containing glass.

Heavy metals remediation through alkali assisted ball-milling activation of copper smelting slag for resource utilization

This study describes the preparation of Silico-Calcium-adhesive (CS-SS) by alkali-assisted ball milling to activate copper smelting slag (CS) for the remediation of heavy metals contamination and consequent resource utilization. The adsorption behavior and mechanisms of Cd(II), Cu(II) and Pb(II) in mono-metallic and polymetallic coexisting systems were investigated. The adsorption capacities of CS-SS were 21.906 mg/g, 30.893 mg/g and 93.593 mg/g for Cd(II), Cu(II) and Pb(II) at a pH of 6, respectively. Based on the experimental results of monometallic system indicated that CS-SS exhibited the highest adsorption capacity for Pb(II), followed by Cu(II) and Cd(II). In the polymetallic system, the inhibitory impact of Pb(II) was more potent compared to Cd(II) and Cu(II). The adsorption mechanisms included electrostatic attraction, chemical adsorption, physical adsorption, ion exchange, functional group complexation and surface precipitation. Simple economic estimates show that it costs about $4.72 to treat 1 m3 of Cd(II)-20 mg/L, Cu(II)-30 mg/L and Pb(II)-90 mg/L containing wastewater. Therefore, the CS treatment method proposed in this study has certain feasibility and economic applicability.

Ball milling coupled cascade magnetic separation to recover valuable metals from alkali disaggregation copper smelting slags

Due to the lack of effective reduction and recycling methods, copper smelting slags (CSS) containing a large number of valuable metals are stockpiled. This work proposed a novel strategy of ball milling coupled cascade magnetic separation to achieve recovery of magnetite and ferrite and enrichment of Cu and Zn in alkali disaggregation CSS. The Fe grade of recovered magnetite reached as high as 72.43%, and 15.51% of Cu and 16.63% of Zn were recovered efficiently as spinel ferrites. Simultaneously, 70.54% of Cu and 58.18% of Zn were enriched in non-magnetic fraction. Compared with primary magnetic fraction, the grade of Fe in the secondary magnetic fraction increased by 19.19%. Additionally, compared with the control, the recovery efficiency and the grade of Fe in the magnetic products after ball milling increased by 52.11% and 49.20%. The main mechanisms were as follows: (1) The significant dissociation of Fe3O4 from non-magnetic impurities and the transformation of Cu and Zn to ferrite were promoted by ball milling. (2) The separation efficiency of weak magnetic ferrite and Fe3O4 was improved by cascade magnetic separation. Therefore, the proposed strategy could provide a green and sustainable solution for CSS processing.

Recovery of Metals from Copper Smelting Slag Using Coke and Biochar

With the purpose of recovering the metal values, in this study the copper slag was reduced by coke and biochar at 1250 °C in an argon gas atmosphere using the isothermal reduction/drop quenching technique. The phase compositions of metal, matte, and slag were determined using electron probe microanalysis (EPMA). The effects of reduction time and amount of reductant were investigated. The distribution of elements between metal/matte and slag was ascertained based on the elemental concentrations determined by EPMA. It was found that copper concentration in slag can be effectively decreased to approximately 0.4–0.6 wt% within 5 min by coke and biochar. Copper and nickel can also be successfully recovered into the copper alloy phase once settling has been accomplished.Graphical

Influence of copper and silicon on phase transformations in the iron – carbon system

Influence of copper and silicon on phase transformations in the iron – carbon system

Preparation of Cementitious Materials from Mechanochemically Modified Copper Smelting Slag Compounded with High-Aluminum Fly Ash.

Copper smelting slag discharged from mining and high-aluminum fly ash generated during the combustion of coal for energy production are two typical bulk solid wastes, which are necessary to carry out harmless and resourceful treatment. This research proposed an eco-friendly and economical method for the co-consumption of copper smelting slag and high-aluminum fly ash. Cementitious materials were compounded with copper smelting slag and high-aluminum fly ash as the main materials were successfully prepared, with a 28-d compressive strength up to 31.22 MPa, and the heavy metal leaching toxicity was below the limits of the relevant standards. The optimum mechanical properties of the cementitious materials were obtained by altering the material proportion, ball mill rotation speed, and CaO dosage. Under the combined effect of mechanical ball milling at a suitable speed and chemical activation with a certain alkali concentration, the prepared cementitious materials had an initial activation. The pastes of the cementitious materials generated a gel system during the subsequent hydration process. The two steps together improved the mechanical strength of the cured products. The preparation was simple to operate and offered a high stability of heavy metals. The heavy metal contaminants were kept at a low content throughout the process from raw materials to the prepared cured specimens, which was suitable for application in practical environmental remediation projects and could provide effective solutions for ecological environment construction.