Copper Smelter Dust Research Articles

Extraction of lead from sulfate cakes of copper smelter dust leaching

Extraction of lead from sulfate cakes of copper smelter dust leaching

Novel Strategy for Efficient Recovery of CuO-Based Multiple-Metals from Copper Smelter Dust toward CO2 Electrocatalytic Reduction.

Copper smelter dust, a typical hazardous waste that is abundant in valuable heavy metals, holds the potential to be regarded as a promising resource. This study introduces a new approach that integrates chlorination roasting and cascade condensation to efficiently recover heavy metals from copper smelter dust. The findings demonstrate the successful separation of heavy metals (Cu, Pb, and Zn) as chlorides at nearly 100% efficiency while also effectively converting trivalent arsenic (As(III)) into pentavalent arsenic (As(V)) and immobilizing it in the roasting residues, thereby reducing environmental risk. Through the utilization of thermogravimetric mass spectrum analysis and thermodynamic equilibrium calculations, the chlorination process for heavy metals was investigated, revealing both direct and indirect chlorination processes. Additionally, the study resulted in the development of a CuO-based multiple-metals electrocatalyst from the oxidized roasting-recovered heavy metal chlorides, exhibiting significantly enhanced catalytic activity and faradaic efficiency for the electroreduction of CO2 into CO and CH4 compared to pure CuO electrocatalyst under similar electrocatalytic conditions. Overall, this work presents a sustainable and scalable method and new insights for addressing environmental risks while repurposing copper smelter dust.

Separation of halogens and recovery of heavy metals from secondary copper smelting dust

The separation of halogens and recovery of heavy metals from secondary copper smelting (SCS) dust using a sulfating roasting−water leaching process were investigated. The thermodynamic analysis results confirm the feasibility of the phase transformation to metal sulfates and to gaseous HF and HCl. Under the sulfating roasting conditions of the roasting temperature of 250 °C and the sulfuric acid excess coefficient of 1.8, over 74 wt.% of F and 98 wt.% of Cl were volatilized into flue gas. Approximately 98.6 wt.% of Zn and 96.5 wt.% of Cu in the roasting product were dissolved into the leaching solution after the water leaching process, while the leaching efficiencies of Pb and Sn were only 0.12% and 0.22%, respectively. The mechanism studies indicate the pivotal effect of roasting temperature on the sulphation reactions from various metal species to metal sulfates and the salting out reactions from various metal halides to gaseous hydrogen halides.

A sustainable approach for recovering copper and zinc from copper smelting flue dust: Paving the path for waste reduction

The recovery of metals without generating secondary waste is a critical focus in the management of hazardous copper smelting dust. To tackle the challenges associated with arsenic-containing solid waste and waste acid generated by traditional recycling processes, we propose a two-stage roasting process that prioritizes low-temperature roasting for arsenic removal, followed by high-temperature roasting for desulfurization of sulfates. This work focuses on the high-temperature desulfurization behavior of residue after arsenic removal. The changes in composition during roasting were analyzed using TG-DSC, XRD, and SEM. The results revealed that the reaction temperature and the addition of bituminite are pivotal in the desulfurization process. The optimal roasting conditions were obtained to be a reaction temperature of 700 °C and a roasting duration of 3 h. Subsequently, approximately 98.77% of copper and 97.17% of zinc could be leached under conditions of a leaching temperature of 80 °C, a reaction time of 4 h, a sulfuric acid dosage of 3 times the theoretical amount, and a liquid-to-solid ratio of 10:1. This process mitigates the generation and accumulation of arsenic-containing waste acid during copper electrodeposition in the traditional hydrometallurgical process of copper smelting flue dust. It lays the foundation for clean and efficient recovery and also provides insights for recycling other copper-containing wastes.

Mechanism and kinetics study on waste acid leaching from copper smelting dust

AbstractCopper smelters generate large amounts of copper smelting dust (CSD) that has a high recycling value because it contains about 20% copper. Waste acid can be used to leach CSD. Here, the effects of different temperatures, times and liquid–solid ratios on copper, iron and arsenic leaching rates were investigated. The optimal conditions were determined to be a temperature of 95°C, leaching time of 3 h, and liquid–solid ratio of 7:1. Under these condition, the leaching rate of copper reached 96.37%, and the copper ion concentration was 32.71 g/L. The leaching kinetics date revealed that the leaching of copper and iron was controlled by two different reaction models. The leaching of copper conformed to the Johnson–Mehl–Avrami (JMA) model and was diffusion controlled, and the reaction was rapid in the first 60 min. In contrast, leaching of iron was controlled by a chemical reaction. Copper and iron activation energies were 2.579 and 62.791 kJ/mol, respectively. These results show that CSD waste acid is can be used to dispose of arsenic‐containing hazardous waste in a green, sustainable, and ecologically method.

A novel process for extracting bismuth from high iron content copper smelting dust by magnetic separation and leaching process

In this study, an efficient method for extracting bismuth from copper smelter flue dust with high content of iron was proposed. In this method recovery of bismuth from copper flue dust was carried out after copper and iron separation. To separate copper from dust, this material was leached with water and dilute sulfuric acid (0.6 M). Magnetic separation was performed with field intensities of 0.1 T and 0.4 T to separate iron in the leaching residue. 70 % of bismuth is placed in the non-magnetic fraction. The non-magnetic fraction of this separation was leached with (1.4 M) H2SO4 + (1 M) NaCl solution to recover bismuth. In optimal conditions, more than 98 % of bismuth in the non-magnetic fraction is leached. Bismuth precipitation from this solution was done by adjusting the pH to 2.5 with the ammonia solution. Impurities such as; Pb, Fe, As, and Cu were precipitated with bismuth in this condition. Lead was removed as a PbCl2 compound by leaching the precipitate with 6 M hydrochloric acid. Other elements were leached in this chloride environment and entered the solution phase. Bismuth was separated from this leaching solution by hydrolysis in the form of BiOCl. The purity of the BiOCl product was about 95 %. This substance can be used in photocatalyst and solar cell industries.

Nanosize-effect on the distribution of heavy metals in copper smelting dust: Based on sophisticated dust sorting approach

Nanosize-effect on the distribution of heavy metals in copper smelting dust: Based on sophisticated dust sorting approach

Recovery of Copper, Lead, Zinc, and Arsenic from Copper Smelting Dust by Oxidative Alkaline Leaching and Sulfide Precipitation

Recovery of Copper, Lead, Zinc, and Arsenic from Copper Smelting Dust by Oxidative Alkaline Leaching and Sulfide Precipitation

An efficient and affordable hydrometallurgical process for co-treatment of copper smelting dust and arsenic sulfide residue

We developed a novel method for comprehensive treatment of copper smelting dust (CSD) and arsenic sulfide residue (ASR) using three processes: leaching CSD by sulfuric acid, Cu precipitation with ASR, and FeSO4·7H2O/O2 co-oxidizing and precipitating As. The novel method not only realizes the recovery of valuable metals from dust, but also removes and solidifies As in CSD and ASR in the form of scorodite to achieve harmless treatment. With sulfuric acid as leaching agent, the leaching efficiencies of Cu, Zn and As reached 87.23%, 93.07% and 95.21%, respectively, under the optimum conditions. Subsequently, Cu in CSD leaching solution was precipitated in the form of CuS by ASR, and the Cu precipitation percentage reached 97.39% and 94.86 wt. % of As in ASR entered the solution under the optimum conditions. Finally, FeSO4·7H2O/O2 was used to co-oxidize As(III) and simultaneously precipitate the As in the form of scorodite. The oxidation percentage and precipitation percentage of arsenic reached 98.73% and 96.77%, respectively. The leaching concentration of As in the arsenic precipitate residue (APR) was only 0.17 mg/L in the toxicity characteristic leaching procedure (TCLP). The arsenic precipitate solution can be directly used to recover Zn.

Selective Recovery of Copper from Acid Leaching Solution through Slow Release Sulfide Precipitant

A new kind of sulfide precipitant, namely, slow release sulfide precipitant (SRSP), was developed and prepared first to realize the selective recovery of copper from an acid leaching solution. The experimental results indicated that SRSP as a precipitant could selectively and efficiently recover copper and the high purity of copper sulfide slag with a Cu grade of 48.16%, and a Cu recovery rate of 97.84% could be obtained. Moreover, copper in leaching solution could be recovered more efficiently and selectively by SRSP compared with Na2S. The results of H2S gas release, chemical reaction energy calculation, and SEM image analyses illustrated that realizing the selective recovery of copper mainly depended on the ions of S2− and HS− produced by the dissolution of SRSP. Moreover, the concentrations of S2− and HS− should always be kept at a low level in the process of selective recovery of copper; this is the biggest difference from the traditional precipitant and the key to preventing the escape of H2S gas in the copper recovery process. More pivotally, SRSP provides an alternative sulfide precipitant for the selective recovery of copper from the acid leaching solution of copper smelting dust.

Ultrasonic-enhanced selective sulfide precipitation of copper ions from copper smelting dust using monoclinic pyrrhotite

The sulfide passivation film produced on the surface seriously prevents further reaction in the process of using monoclinic pyrrhotite (MPr) to treat heavy metal ions in wastewater. Ultrasonic technology was introduced to assist MPr to recover the copper ions. XPS result proves that CuS products exist on the surface of MPr. XRD and SEM results show that the CuS on the particles’ surface is stripped under ultrasonic condition. The kinetics results indicate that the reaction under both conventional and ultrasonic conditions conform to the Avrami model. The reaction process changes from diffusion control to chemical reaction control under the ultrasonic condition as the solid layer is stripped off. The presence of ultrasonic significantly reduces the acidity and temperature required for the reaction and enhances the utilization efficiency of MPr; by controlling the amount of MPr, the removal rates of copper and arsenic in copper smelting dust leachate exceed 99% and 95%, respectively.

Evolution of Arsenic-Containing Phase and Reaction Mechanism During Vacuum Vulcanization Roasting for Arsenic Removal in Copper Smelting Dust

Evolution of Arsenic-Containing Phase and Reaction Mechanism During Vacuum Vulcanization Roasting for Arsenic Removal in Copper Smelting Dust

Treating Secondary Copper Smelting Dust: Selective Separation of Harmful Halogen and Comprehensive Recovery of Valuable Heavy Metal

Treating Secondary Copper Smelting Dust: Selective Separation of Harmful Halogen and Comprehensive Recovery of Valuable Heavy Metal

Detoxification of Arsenic-Containing Copper Smelting Dust by Electrochemical Advanced Oxidation Technology

A large amount of arsenic-containing solid waste is produced in the metallurgical process of heavy nonferrous metals (copper, lead, and zinc). The landfill disposal of these arsenic-containing solid waste will cause serious environmental problems and endanger people’s health. An electrochemical advanced oxidation experiment was carried out with the cathode modified by adding carbon black and polytetrafluoroethylene (PTFE) emulsion. The removal rate of arsenic using advanced electrochemical oxidation with the modified cathode in 75 g/L NaOH at 25 °C for 90 min reached 98.4%, which was significantly higher than 80.69% of the alkaline leaching arsenic removal process. The use of electrochemical advanced oxidation technology can efficiently deal with the problem of arsenic-containing toxic solid waste, considered as a cleaner and efficient method.

Separation of arsenic and extraction of zinc and copper from high-arsenic copper smelting dusts by alkali leaching followed by sulfuric acid leaching

Separation of arsenic and extraction of zinc and copper from high-arsenic copper smelting dust (HACSD) is one of the difficulties in the world. A two-stage countercurrent alkali leaching followed by one-stage sulfuric acid leaching for arsenic separation and zinc and copper extraction was developed in this work. The dusts properties, metals leaching behaviors and their phase transformations in the alkali leaching and sulfuric acid leaching were explored systematically. Results indicate that >95.5% of As was successfully separated from HACSD into alkali leachate. Arsenic and metals (Zn, Pb, Bi, Sn) contents were up to 61.50 g·L−1 and as low as 0.001–0.21 g·L−1 in alkali leachate, respectively. >97.2% of Zn and >96.4% of Cu were extracted from the alkali leaching residues into sulfuric acid leachate. The sulfuric acid leaching residues were enriched with 34.16% of Pb, 8.38% of Bi and 11.54% of Sn in oxides and sulfates phases. The metals leaching behaviors, phase transformations and microstructure of metal compounds during the leaching processes were confirmed by X-ray diffraction and scanning electronic microscopy/energy dispersive spectroscopy. The proposed process offered high separation efficiency of arsenic, zinc and copper, as well as low environmental pollution.

Effect of Metal Oxides and Smelting Dust on SO2 Conversion to SO3

The purpose of this study was to investigate the effects of metal oxides and smelting dust on the formation of sulfur trioxide during copper, lead, zinc smelting process and flue. Focusing on the effects of SO2 concentration, O2 concentration, and temperature on SO2 oxidation conversion rate under homogeneous test conditions, and under various metal oxide oxidation conditions, further in dust (mainly electric dust removal ash in copper, lead, zinc smelting process), which were studied by single factor experiment test. The results showed that the effect of heterogeneous catalytic oxidation on SO2 conversion rate is much greater than that of pure gas phase oxidation. The addition of five pure metal oxides such as Fe2O3, CuO, Al2O3, ZnO, and CaO obviously promoted the SO2 conversion rate under different conditions. At different temperatures, the ability of metal oxides to promote SO2 conversion is ranked: Fe2O3 > CuO > CaO > ZnO > Al2O3. The catalytic oxidation of copper, lead, and zinc smelting dust to SO2 conversion rate was studied, and the conclusion was drawn that the metal oxides that promoted SO2 conversion rate in copper smelting dust were Fe2O3, Al2O3, ZnO, CaO, and the main substance was Fe2O3; the metal oxides that promoted SO2 conversion in zinc smelting dust were Fe2O3, Al2O3, ZnO, CaO, CuO, and the main substances were Fe2O3 and ZnO; the metal oxides that promoted SO2 conversion rate in lead smelting dust were Fe2O3. Whether metal oxides or copper, zinc, lead smelting dust in the experiment, Fe2O3 displayed the strongest catalytic oxidation capacity.

Alkali circulating leaching of arsenic from copper smelter dust based on arsenic-alkali efficient separation

Leaching arsenic from solid waste selectively and removing arsenic from alkaline leachate efficiently are two key points in alkali treatment of copper smelter dust, and the latter is challenging. In this study, composite salt precipitation of magnesium ammonium arsenate (NH4MgAsO4·6H2O), similar to magnesium ammonium phosphate (NH4MgPO4·6H2O), was proposed to solve the difficult problem of separation arsenic from alkali. Based on the thermodynamic analysis, the selective leaching of arsenic from copper smelting dust was carried out in the NaOH-Na2S system. In the alkali leaching system, more than 80% arsenic can be leached out from the dust with the diffusion-controlled type in the Avrami model, while the leaching rates of valuable metals are less than 0.5%. For the strong alkaline leachate containing arsenic obtained by alkali leaching, the selective removal of arsenic was achieved by adding magnesium salt and ammonium salt. With the change of the amount of magnesium salt and ammonium salt, the sedimentation performance and composition of the arsenic slag changed accordingly. At the mole ratio of NH4+: As = 8:1 and Mg2+: As = 1.5:1, 96.38% of arsenic was removed, and the content of arsenic in the arsenic slag composed of MgNH4AsO4·6H2O reached 28.96%. On this basis, the circulating alkali leaching of copper smelter dust based on arsenic-alkali separation was successfully carried out. The whole scheme is not only economical and safe, but also achieves the reuse of wastewater without secondary pollution, which provides an alternative solution for the treatment of arsenic containing solid waste.

Comprehensive recovery of arsenic and antimony from arsenic-rich copper smelter dust

In view of reducing contaminant and recovery arsenic and antimony, a novel technology was proposed to recover arsenic and antimony from arsenic-rich copper smelter dust comprehensively. The technique route includes three stages: arsenic and antimony trioxides were leached from the copper smelter dust with hydrochloric acid; trivalent arsenic ions (As3+) were then reduced to less toxic simple arsenic (As) by sodium hypophosphate (NaH2PO2) and recovered; and stepwise recovery of antimony by SbCl3 was achieved by the continuous distillation technique. The results indicates that the leaching efficiency of As and Sb was over 97.5% and 96.8% under conditions of initial 4.0 mol/L HCl, liquid-solid ratio (L/S) of 6:1, leaching temperature of 363 K and time of 2 h. Over 92.5% arsenic was recovered by NaH2PO2 reduction under the suitable conditions: 363 K, 1.5 h and 2.0 times addition of NaH2PO2. The recovery rate of Sb is more than 97.53% at 393 K. The distillation temperature of SbCl3 was optimized between 463 K and 473 K. The corresponding mechanisms of the leaching and recovering of arsenic and antimony were systematically investigated and confirmed by E-pH diagram, thermodynamic calculation, arsenic speciation, composition analysis and XRD characterization.

Hydrometallurgical Processing of Copper-Smelting Dust

Hydrometallurgical Processing of Copper-Smelting Dust

Oxidative roasting experimentation and optimum predictive model development for copper and iron recovery from a copper smelter dust

The success of a treatment option depends on selection of suitable process variables at which response attains optimum. Hence, this study aimed at investigating the effects of time, temperature and time-temperature on changes in mineralogy (copper sulphate (CuSO4), copper oxide (CuO), ferrous oxide (Fe2O3) and ferric oxide (Fe3O4)) of a copper smelter dust (CSD) during oxidative roasting. This aim was achieved by 2-way analysis of variance and mathematical model development of data obtained. Results showed time as most influential factor with an optimum time of 2 ​hrs for the production of high yield roast products. Furthermore, it was observed that a maximum of 23.31% proportion of CuSO4 was recovered from an input with 7.86% proportion of CuSO4 at a temperature of 680 ​°C within a time frame of 2 ​hrs and for a furnace door opening of 25 ​mm. Similarly, a maximum of 18.37% of CuO was recovered from an input with 23.91% CuO at a temperature of 800 ​°C, for a duration of 3 ​hrs and 25 ​mm opening of the furnace door. Whereas, an optimum 0.44 ratio value of Fe2O3:Fe3O4 was recovered at a temperature 680 ​°C, for a duration of 2 ​hrs and 25 ​mm furnace door opening. These maximum outputs and associated experimental conditions depict optimum operating conditions of experiment. Furthermore, predicted output proportions obtained from developed constraint interpolant models were well aligned with experimental outputs. A maximum percentage error of 0.07% was recorded in the predictive output for both water and acid soluble mineral fractions.