Copper Slag Research Articles

High-value terminal treatment: Utilizing copper slag heat in the manufacture of copper-containing weathering steel

Copper slag, a bulk non-ferrous solid waste, is critical in establishing a closed-loop cycle in the copper metallurgy industry. Currently, the processing techniques for copper slag are characterized by prolonged procedures, secondary waste discharge, limited value utilization, and high energy consumption. A novel approach was proposed to harness the thermal energy inherent in molten copper slag for producing copper-bearing weathering steel and cement while simultaneously synergistically recovering lead and zinc. The results indicate that under the conditions of smelting temperature of 1500 °C, alkalinity of 1.06, smelting time of 60 min, and mechanical stirring, the recovery rates of copper, iron, lead, and zinc in copper slag reached 98.83%, 99.59%, 97.45%, and 98.51%, respectively. Furthermore, the feasibility of this approach was validated by laboratory-scale preparation of Q355GNH-grade copper-bearing weathering steel and S95-grade cement clinker. Computational analysis for the direct carbothermal reduction of molten copper slag in its thermal state reveals that, compared to the traditional flotation process, this approach saved 1177 MJ of thermal energy per metric ton of copper slag, equivalent to a reduction of 147 kg of carbon dioxide emissions. This study facilitates the zero-waste, high-value, and sustainable development of the copper smelting industry.

Transforming temperature effects on TiO2/iron oxide composite derived from copper slag as a photocatalyst for glucose conversion

Amorphous copper slag (CS), a by-product of the matte smelting and refining processes in copper smelting, contains approximately 47 % iron. This study explores the potential of using CS as an iron source to create a photocatalyst composite with TiO2 through calcination at various temperatures (550, 700, 850, and 1000 °C) in order to achieve efficient photocatalytic conversion of glucose to lactic acid under visible light irradiation (λ ≥ 380 nm) at room temperature. All the calcined composites exhibited superior glucose conversion and lactic acid production compared to the uncalcined composite (CT) and pure TiO2. The composite calcined at 700 °C provided the highest yield and selectivity for lactic acid. This improvement is attributed to the optimal ratio of Ti(III)/Ti(IV) and the effective separation of photogenerated electron-hole pairs via the Z-scheme heterojunction in the calcined CT composite. This process contributes to the circular economy by recycling waste materials to produce higher-value-added chemicals from biomass using sustainable energy sources.

Copper Slag as an Alternative to Silica Sand for A356 Alloy Casting-Feasibility Study

Copper Slag as an Alternative to Silica Sand for A356 Alloy Casting-Feasibility Study

Recycling of Stabilized Copper Slag Waste for Sustainable Road Embankment Construction: A Pilot Study

Recycling of Stabilized Copper Slag Waste for Sustainable Road Embankment Construction: A Pilot Study

Optimization of Copper Recovery and Fluorine Fixation from Spent Carbon Cathode Reduction Copper Slag by Response Surface Methodology

Optimization of Copper Recovery and Fluorine Fixation from Spent Carbon Cathode Reduction Copper Slag by Response Surface Methodology

Interphase migration and enrichment of lead and zinc during copper slag depletion

An interphase migration and enrichment model of lead and zinc during molten copper slag depletion was established. The occurrence of various components in copper slag was predicted using sulfur−oxygen potential calculations and confirmed through high-temperature experiments. The recovery rate of copper can reach 90.13% under the optimal conditions of 1200 °C, an iron to silicon mass ratio of 1.0, 3 wt.% ferrous sulfide, and a duration of 45 min. Lead (54.07 wt.%) and zinc (17.42 wt.%) are found in the flue dust as lead sulfate, lead sulfide, and zinc oxide, while copper matte contains lead (14.44 wt.%) and zinc sulfide (1.29 wt.%). The remaining lead and zinc are encapsulated as oxides within the fayalite phase.

Characterization of Taguchi optimized fiber reinforced copper slag concrete composites with strength properties

Establishing the ideal design has always been a difficulty for concrete engineers because of the inclusion of many alternative construction materials particularly when dealing with the incorporation of slag elements and fibers in concrete mix design. In this study, the Taguchi optimization method is implemented to predict the optimal mix design of fiber reinforced copper slag aggregate concrete (FRCSC) with mechanical strength properties. For this purpose, different parameters influencing mechanical strength were defined based on the available literature. The Taguchi approach was subsequently applied to develop an orthogonal array of parameters, and experimental tests were carried out in accordance with the suggested design array to acquire experimental data for each and every strength property. Three major influencing parameters like fiber length (FL), fiber percentage (FP), and copper slag content (CS) were considered in order to get optimal mix design for FRCSC. Analysis of variance was also employed to evaluate the effective factors on compressive, split-tensile, flexural, water absorption and void content properties for FRCSC. It was found that the proposed method was effective in finding the optimal mixture design from strength point of FRCSC and the experimental results indicated a significant improvement in five selected strength properties of FRCSC. From the results of Taguchi analysis, it can be concluded that, for five selected strength properties, 60% CS + 1% of fiber + 20 mm of fiber length is the optimal mix design combination for FRCSC. Finally, physical and microstructural characterization through FESEM and EDX were carried out to have a closer justification for the test results.

Iron extraction from copper slag by additive-free activation roasting-magnetic separation

Iron grain growth during deep reduction roasting is important for iron enrichment from copper slag (CS) through magnetic separation. In this work, a novel method of additive-free activation roasting, including oxidation and subsequent reduction roasting, was proposed to increase the iron grain size, then the iron was extracted by magnetic separation. The phase transformation of CS during activation roasting was studied by TG, XRD, SEM, and EDS. Results showed that the main mineral of fayalite in CS was decomposed into iron oxides and silica during oxidation roasting, and the thickness of iron oxide layer on the particle surface increased with the oxidation temperature. During reduction roasting, the CS and oxidized copper slag (OCS) were ultimately converted into metallic iron and cristobalite solid solution. In the reduced product obtained at 1150 °C, the iron grain sizes were 6.42 μm and 16.62 μm from CS and OCS-1100 °C, respectively. Furthermore, the Fe content in the magnetic concentrate was 72.86 % in the reduced product of CS while that was 87.85 % in the reduced product of OCS-1100 °C with an Fe recovery of ∼ 85 %. This study opens a new direction for iron enrichment from copper slag.

Study on Strength and Durability Properties of Concrete by Partial Replacement of Fine Aggregate with Copper Slag and Cement with Eggshell Powder

Study on Strength and Durability Properties of Concrete by Partial Replacement of Fine Aggregate with Copper Slag and Cement with Eggshell Powder

Comparative study on preparation and hydration mechanism of composite cementitious materials containing copper slag

Copper slag (CS) is a kind of non-ferrous solid waste with low content of aluminosilicate and relatively high content of iron oxide. In this paper, the feasibility and mechanism of CS as the mineral admixture and precursor of alkali activated cementitious material were studied. The effects of CS on mechanical properties were studied and the hydration products were determined by several characterization methods. Scanning Electron Microscopy (SEM) and Mercury Injection Porosimetry (MIP) were performed to characterize the microstructure. The results show that CS composite fly ash (FA) has more advantages than CS alone, but its application as a mineral admixture is limited by the low activity. The alkali activated cementitious material prepared by CS and FA as precursor has excellent mechanical properties. The compressive strength of specimen at 28 days age can reach the maximum of 81.3 MPa when the dosage of CS is 30 %. The 3d and 28d compressive strength of the specimen contained 60 % CS obtained 57.7 MPa and 70.7 MPa, respectively. The research exhibits great potential for the future utilization of CS.

Investigation of converter copper slag reduction using spent cathode carbon as a reductant

ABSTRACT Aiming to address the difficulty of harmless treatment of fluorine in spent cathode carbon (SCC) and high metal content in copper slag, a new method of sustainable production of Fe-Cu alloys by reducing converter copper slag with SCC is proposed. Thermodynamic studies show that Fe-Cu alloys can be obtained at temperatures higher than 1250 °C and fluorine can be effectively fixated. Feasibility experiments were carried out in conjunction with theoretical analyses to clarify the feasibility of the method. At 1500 °C, the recovery of copper and iron reached 93.37% and 78.51%, respectively. During the smelting process, the iron-bearing phases in the slag forms Fe-Cu alloys with copper under high temperatures reducing conditions, and the fluorine is fixated in the slag through conversion to CaF2. This method achieves the effective utilisation of SCC during the reduction smelting process. The phase transformation and thermodynamics of the reduction process were investigated, and reaction mechanism was revealed. The process provides new ideas and perspectives for the environmentally sound treatment of SCC through a pyrometallurgical processes.

Design and assessment of a concentrating solar thermal system for industrial process heat with a copper slag packed-bed thermal energy storage

Decarbonising the industrial sector is a key part of climate change mitigation targets, and Solar Heat for Industrial Process (SHIP) is a promising technology to achieve this. However, one of the drawbacks of SHIP systems is that they rely on an intermittent energy source. Therefore, sensible energy storage has emerged as a potential solution. In addition, solid byproducts have been proposed as a low-cost but effective material for thermal energy storage (TES). This work presents a SHIP system model coupled with a copper slag-packed-bed TES (PBTES) model using air as heat transfer fluid. The TES has been implemented to preheat the makeup water of the tank where steam is generated. A system design was carried out using a parametric analysis to find a solar field size and a corresponding TES volume. The resulting system was simulated, and the operating variables were analysed in detail. The results show that it is possible to generate 20% more energy due to the storage system. Additionally, a techno-economic analysis indicates that the SHIP with PBTES system results in a payback period of 14 years and a savings of CO2 emissions of 30tCO2.

Experimental study on effective utilization of industrial solid wastes in developing Ultra-High Performance Geopolymer Concrete

<p><a><span style="font-size:12.0pt"><span style="line-height:115%"><span style="font-family:"Times New Roman",serif">This experimental study explores the use of Ground Granulated Blast Furnace Slag(GGBS) and dolomite as alkali activated binders and copper slag as aggregate to achieve a cost-effective and sustainable Ultra-High-Performance Geopolymer Concrete(UHPGC). Several concrete compositions utilizing copper slag as a substitute for natural aggregates were formulated. Tests have shown that the inclusion of 100% copper slag fine aggregate leads to significant improvements in the mechanical properties and density of geopolymer concrete. Specifically, the compressive strength increased by 56.8% and the density increased by 17.5%. To understand the influence of dolomite in GGBS binder, several mixes varying dolomite proportion in GGBS were examined. The compressive strength of the 80% GGBS/20% dolomite geopolymer matrix is 32.8% higher compared to the compressive strength of UHPGC with 100% GGBS. The UHPGC mixture containing 1% crimped steel fibers showed the highest compressive strength, measuring 146.6 MPa. The split tensile and flexural strengths of the 20% dolomite matrix show a significant increase of 30.55% and 30.24% respectively compared to the 100% GGBS matrix. The water absorption and porosity of the 100% GGBS specimen were found to be lower compared to the 20% dolomite UHPGC specimen. The microscopic study reveals the positive impact of dolomite and GGBS on enhancing the bonding of the geopolymer matrix along with decreasing permeability. This study highlights the potential of geopolymer technology in producing ultra-high-performance concrete using GGBS, dolomite, and copper slag.</span></span></span></a></p>

Pyrometallurgical Reduction of Copper Slag with Biochar for Metal Recovery

Large amounts of slag are generated during pyrometallurgical processing in copper production. Due to the presence of valuable elements, the improper disposal of huge quantities of copper slag produced, results in significant loss of resources as well as environmental issues. Analyses of the copper slag show that it contains valuable metals, particularly copper and nickel. In this work, four biochars were employed as fossil-free reducing agents to recover valuable metals from the slag. Reduction experiments were performed in a vertical furnace at temperatures 1250, 1300 and 1350 °C for 60 min in order to investigate the effect of temperature. Moreover, the effect of time on reduction progress was studied at 1250 °C and the concentrations of CO and CO2 in the off-gas were measured with a gas analyzer. Copper slag was reacted with metallurgical coke for comparison and the products were analyzed with EPMA and LA-ICPMS. The results revealed that reduction rapidly progresses to the formation of metal alloy within 10 min. Valuable metals like copper, nickel and arsenic were the first to be reduced to the metal phase. As reduction time increased, iron was also reduced and combined with the metal droplet. The use of biochar as reductant was shown to be more effective than coke especially at lower temperatures. In addition, thermodynamic modelling was performed with FactSage and HSC and compared with the experimental results. The simulations with HSC showed the sequence of reactions taking place and the calculations by FactSage were in agreement with the experiments.Graphical

Development of a Sustainable Flax Fiber- Geopolymer Composite Matrix Incorporated with Copper Slag as a Filler

<p>Efforts have been put forth in the past to develop sustainable construction material by reducing the use of cement and river sand which can directly provide a positive impact on our ecosystem. In this work, an attempt is made to develop a sustainable a geopolymer composites with the use of fly ash (FA) and Ground Granulated Blast Furnace Slag (GGBS) as precursor binder and copper slag as a complete replacement for conventional fine aggregate. In addition, discrete natural fiber such as flax is added to the composite matrix to provide sufficient tensile strength and better bonding capabilities. The fiber volume fractions were fixed as 0.25%, 0.50%, and 0.75% to the total volume of the composite matrix. All the cast specimens undergo an ambient curing process to complete the polymerization mechanism for strength gain. Results reveal that the geopolymer composite mix with 0.25% of flax fiber was found to outperform the other mixes based on the enhancement in mechanical strengths. Moreover, the addition of fibers of more than 0.5% results in the marginal reduction of compression and flexural tests which could be due to the improper fiber dispersion or fiber bundling at specific locations leading to the absence of required fibers at the fracture plane. In addition to the mechanical tests, a detailed micro-structural analysis was performed using the scanning electron microscopy (SEM) to understand the interface between the fiber and the matrix.</p>

Preparation of lightweight foam glass-ceramics from copper slag tailings: Secondary aluminum slag as pore-forming agent

To address metallurgical waste residue pollution, this study utilized copper slag tailings (CST) and waste glass (WG) as primary raw materials, with secondary aluminum dross (SAD) as a pore-forming agent, to produce lightweight spontaneous foam glass-ceramics. The effects of raw material ratios, sintering temperature (1120–1160 °C), and sintering time (0–40 min) on foam glass-ceramics properties were investigated, elucidating the correlations between various properties. Under optimal preparation conditions (CST: WG: SAD = 7:11:2, sintered at 1150 °C for 20 min), the foam glass-ceramics exhibited a bulk density of 0.41 g/m³, compressive strength of 2.32 MPa, open porosity of 61.02 %, 2-h water absorption of 83.76 %, and mean pore size of 3.12 mm. The sintering process transformed raw materials into substances like diopside subsilic ferrian, which enhanced the strength of lightweight foam glass-ceramics. Harmful substances in the raw materials can be immobilized within the internal structure of foam glass-ceramics, ensuring excellent environmental safety. Additionally, comprehensive characterization was conducted on the foam glass-ceramics, elucidating their composition, structure, and pore-forming mechanisms.

Exploration of sulfamethoxazole removal triggered by copper slag-based geopolymer: Radical versus nonradical contributions

The advanced oxidation processes based on sulfate radicals offer environmental sustainability and exhibit potential for effectively breaking down antibiotics. Among various iron-based materials for activating peroxydisulfate, copper slags are iron-rich raw material and can serve as an excellent catalyst. In this study, acid-activated copper slag-based geopolymers were successfully synthesized using a 1:1 mass ratio of copper slag and metakaolin as raw materials. In the geopolymer based electrocatalytic system, the removal of sulfamethoxazole (SMX) was 99.1 % within 60 mins under the optimized operating conditon of initial pH 3.0, current density of 20 mA/cm2, inter-electrode distance of 3 cm, geopolymer dosage of 1 g/L, and electrolytic concentration of 75 mM/L. The presence of GP provided surface Fe(II) to further activate H2O2 and peroxydisulfate and hence promote the degradation of SMX. Electron paramagnetic resonance spectroscopy, quenching experiments, electrochemical techniques, and probe analysis, were employed to investigate the radical and nonradical pathways within the system. The reactive oxygen species identified in the proposed system included hydroxyl radicals (·OH), sulfate radicals (SO4·-), and singlet oxygen (1O2). SO4·- was the predominant reactive oxygen species, playing a crucial role in the radical pathway with a contribution of 62.1 %. 1O2 was the sole nonradical pathways involved, exerting limit influence on SMX degradation. Additionally, six potential intermediate pathways for SMX degradation were identified. This research not only systematically offers a comprehensive understanding of the oxidation mechanisms in heterogeneous electro-catalytic systems but also demonstrates a high-value utilization strategy of metallurgical industrial solid waste for resource recycling.

Influences of silicate modulus and alkali content on macroscopic properties and microstructure of alkali-activated blast furnace slag-copper slag

The stacking of copper slag (CS) has led to the resource wastage and environmental issues. Utilizing CS as a green precursor in the production of alkali-activated materials (AAMs) offers a promising avenue for sustainable resource usage. To obtain a deeper understanding and enhance its practical application, the effects of silicate modulus and alkali content of water glass (WG) on the performances of alkali-activated blast furnace slag-copper slag (AAS-CS) are systematically investigated though the fluidity, setting time, hydration heat, compressive strength and drying shrinkage rate. Additionally, the microstructure is characterized using nuclear magnetic resonance (NMR), X-ray diffraction (XRD), Fourier transform infrared spectrum (FTIR) and scanning electron microscope (SEM), respectively. When the alkali content is a constant of 6.0 wt%, the compressive strength and drying shrinkage rate initially increases with increasing silicate modulus, but eventually decrease beyond a certain threshold. At a given silicate modulus of 1.5, the compressive strength and drying shrinkage rate firstly increases and then decrease as increasing the alkali content from 4.0 wt% to 8.0 wt%. The microstructure analyses reveal that the suitable silicate modulus and alkali content promote the dissolution of precursors to form C-A-S-H gels. The M1.5N6.0 sample has a relatively tight microstructure, which benefits to the development of compressive strength, but increases the capillary stress. Therefore, the M1.5N6.0 sample has the highest 28-day compressive strength of 71.7 MPa and the largest 182-day drying shrinkage rate of 0.1532 %.

Simultaneous Removal of NOx and SO2 from Smelting Flue Gas Using Thermally Modified Copper Slag: Factor Optimization via Response Surface Methodology

AbstractIn this study, Response Surface Methodology (RSM) was employed to optimize the experimental factors influencing the simultaneous removal of NOx and SO2 in a spray tower wet scrubbing experiment. Thermally modified copper slag (CS‐CaO‐900) was prepared by heat treating the original copper slag. The performance of CS‐CaO‐900 in the synchronized removal of NOx and SO2 was then evaluated in an expanded experimental setup. Based on single‐factor experimental results, the Box‐Behnken design of RSM was used to optimize the reaction parameters in a two‐stage sequential reactor (bubbling reactor + spray tower). NOx removal efficiency was modeled as a function of reaction temperature, pH, and H2O2 concentration. Regression curves provided a visual representation of the interaction effects among these parameters on NOx removal efficiency in the thermally modified copper slag/H2O2 composite slurry. This study elucidates the characteristics of each parameter under wet scrubbing conditions and provides essential data for industrial applications.

Study on the Co-pyrolysis Behavior of Copper Slag and Pine Sawdust and the Adsorption of Chromium

Study on the Co-pyrolysis Behavior of Copper Slag and Pine Sawdust and the Adsorption of Chromium