Anode Slime Research Articles

An environmentally-friendly method to recover silver, copper and lead from copper anode slime by carbothermal reduction and super-gravity

In the present study, an effective and green method to recover silver, copper and lead from copper anode slime by carbothermal reduction and super-gravity separation was investigated. During the pretreatment process, 99.9% of selenium was removed from copper anode slime after sulphation roasting, and the valuable metals of lead, copper and silver were concentrated as the lead-silver-copper multiphase complex by carbothermal reduction. The influence of temperature on the reduction efficiency was studied and the results obtained were supported by thermodynamic analysis. Under the optimal super-gravity separation conditions of G = 600, T = 1423 K and t = 5 min, the filtrated lead-silver-copper multiphase complex and residual phases were obtained. Results showed that the yield of the filtrated Pb-Ag-Cu phase was about 83% and the recovery efficiencies of lead, silver and copper exceeded 98%, 96% and 89%, respectively. These residues could be recycled to the pretreatment processes. Finally, based on the phase diagram analysis and equilibrium calculations, the lead-silver and copper-silver phases can be obtained and this was demonstrated after super-gravity enrichment. This work confirmed that super-gravity technology was a feasible approach in the recovery of valuable metals from copper anode slime due to its significant advantages of high efficiency, simple operation, and being more environmentally-friendly.

New Processes to Treat Anode Slime and Other Smelter Improvements

During efforts to solve common technical challenges to the comprehensive recovery of rare precious metals associated with copper smelting, Xiangguang Copper (XG) independently developed a new process to treat anode slime using technology that captures precious metal using bismuth. This paper focuses on the introduction and application of this technology for capturing precious metals with bismuth. It also discusses silver electrolysis at high current density and bismuth recovery from precious metals slag. The new process shows good adaptability of raw materials, elimination of lead pollution, low energy consumption, environmental protection and high comprehensive recovery rate of metals, which promotes the technological progress of comprehensive recovery and utilization of associated resources in copper smelting process.

Synergistic mechanism and decopperization kinetics for copper anode slime via an integrated ultrasound-sodium persulfate process

An eco-friendly synergistic decopperization method via ultrasound and sodium persulfate was developed from copper anode slime (CAS), a hazardous solid waste. The advanced oxidation process was applied to the field of metal leaching/enrichment in hydrometallurgy. Electron paramagnetic resonance (EPR) spectroscopy was used to trace the free-radical quenching mechanism in the leaching experiment. The influence of different conditions on copper leaching efficiency was studied. A total of 98.11% of copper was removed by the synergistic process from CAS. By comparison, the leaching efficiency of copper by persulfate leaching under the same conditions was only 66.64%. The kinetics model fitting results indicate that ultrasound reduced the threshold of the leaching reaction. The leaching reaction order values of the H2SO4 and Na2S2O8 concentrations are 0.11 and 0.69, respectively, which shows that persulfate plays a major role in leaching efficiency in the decopperization process. Mineralogical analysis demonstrated that the insoluble copper was effectively transformed into copper sulfate via ultrasound and sodium persulfate. In addition, hazardous solid waste was converted to valuable high-grade metallurgical stock through the enrichment of rare noble metals in CAS using a cooperative process. The novel decopperization method via integrated ultrasound/sodium persulfate has wide application prospects in waste management and recycling in a clean and economical hydrometallurgical process.

Chemical Composition Data of the Main Stages of Copper Production from Sulfide Minerals in Chile: A Review to Assist Circular Economy Studies

The mining industry has faced significant challenges to maintaining copper production technically, economically, and environmentally viable. Some of the major limitations that must be overcome in the coming years are the copper ore grade decline due to its intense exploitation, the increasing requirements for environmental protection, and the need to expand and construct new tailings dams. Furthermore, the risk of a supply crisis of critical metals, such as antimony and bismuth, has prompted efforts to increase their extraction from secondary resources in copper production. Therefore, improving conventional processes and developing new technologies is crucial to satisfying the world’s metal demands, while respecting the policies of environmental organizations. Hence, it is essential that the chemical composition of each copper production stage is known for conducting these studies, which may be challenging due to the huge variability of concentration data concerning the ore extraction region, the process type, and the operational conditions. This paper presents a review of chemical composition data of the main stages of copper production from sulfide minerals, such as (1) copper minerals, (2) flotation tailings, (3) flotation concentrates, (4) slags and (5) flue dust from the smelting/converting stage, (6) copper anodes, (7) anode slimes, (8) contaminated electrolytes from the electrorefining stage, (9) electrolytes cleaned by ion-exchange resins, and (10) elution solutions from the resins. In addition, the main contributions of recent works on copper production are summarized herein. This study is focused on production sites from Chile since it is responsible for almost one-third of the world’s copper production.

The Mechanism of Selective Separation of Antimony from Chloride Leachate of Copper Anode Slime

The mechanism of selective separation of antimony from copper anode slime leachate is studied. Density functional theory is used to calculate the unit cell energy, band structure, density of states, number of charge distributions and overlap populations of the SbCl3 hydrolysates SbOCl, Sb3O4Cl and Sb4O5Cl2, and these are studied by infrared spectroscopy. The pathways for formation of SbOCl, Sb3O4Cl and Sb4O5Cl2 in water, ethanol and ethylene glycol systems are clarified. The results show that the energy of the SbOCl unit cell is the lowest, and the structure is more stable. SbOCl exhibits strong electronic localization, weak orbital expansion, and more stability; SbOCl has a wider pseudoenergy gap, and its covalent bonds are stronger than those of Sb3O4Cl and Sb4O5Cl2. Hydrolysis of SbCl3 leads to preferential generation of more stable structures. The charge distribution, the sizes of overlap populations, and the infrared spectra indicate that SbCl3 has been hydrolysed. There are two basic paths for the process of alcoholysis: a water- or alcohol-ionized hydroxyl replaces one chlorine atom in SbCl3 to form an [Sb(OH)Cl2] monomer, and as the degree of hydrolysis increases, the H and Cl atoms are removed to form SbOCl. Conversely, Sb3O4Cl, Sb4O5Cl2 or Sb atoms may be formed an [Sb-OH] monomer generated directly by water- or alcohol-ionised hydroxyl groups, and Cl atoms replace the H atom in the hydroxyl group of the [Sb-OH] monomer to form SbOCl, Sb3O4Cl and Sb4O5Cl2.

A green process for simultaneously efficient base metals removal and precious metals enrichment from copper anode slime

In this study, a green process consisting of NaOH roasting - water leaching - synergistic acid leaching with only low-concentration and green reagents employed, was developed for simultaneously efficient base metals removal and precious metals enrichment from copper anode slime. Results showed that: (1) phases prepared by the first NaOH roasting under the NaOH/slime ratio of 1.0, roasted at 700 °C for 2.0 h, was easier to remove base metals but harder to extraction PMs; (2) 76.39% Pb, 79.29% Sn, 87.72% S and 95.20% As were dissolved by the second water leaching; (3) main base metals including 99.68% Cu, 81.99% Ni and 99.94% Sb were removed by the final synergistic acid leaching under H2SO4 of 2.00 mol/L, tartaric acid of 0.33 mol/L, H2O2 of 0.44 mol/L, the solid-liquid ratio of 25 g/L and 80 °C. As a result, 99.98% Ag, 99.50% Au and 91.00% Pd were retained with their contents enriched by 517.08%, 330.77%, and 400.00%, respectively. The calculated negative Gibbs Free Energy Changes indicated that the roasting reactions can proceed spontaneously. Moreover, electric potential-pH analysis of the acid leaching unit suggested that the effective removal of Sb and high retention of Ag was attributed to the complexation of tartaric acid and its interaction with H2O2. In addition, the valuable base metals in the leachates were successfully recovered. Therefore, the process could be a novel green technology for simultaneously efficient base metals removal and precious metals enrichment from copper anode slime.

Mechanism and kinetics of gold leaching from copper anode slime using BmimHSO4 as green solvent

AbstractThe cyanide process, as the most common approach in the recovery of gold by hydrometallurgical, suffers from its high toxicity to the environment. The effect of practical parameters, viz., temperature, time, concentration, mechanical activation, and the stirring rate, was investigated using a combination of H2O2, BmimHSO4, and thiourea as green solvent to recover the gold from anode copper slime in an electrorefining plant. The leaching kinetics of Au in the selected slime was also investigated. The results showed that leaching reaches 93.48% after 20 h in the activated sample for 10 h at the temperature of 313.15 K and solvent including 60% (v/v) BmimHSO4, 50 g/L thiourea, 1/15 g/ml pulp density, 25 g/L H2O2, and an agitation speed of 400 rpm. Moreover, the leaching of Au follows the shrinkage particle model, and the diffusion of a solvent through the leaching product was the administrated mechanism. The proposed green solvent can also dissolve gold effectively and is an excellent candidate to replace harmful cyanide‐based solvents.

The Occurrence Behaviours of As/Sb/Bi in Copper Anode Slime and Their Separation by Compound Leaching Followed by Stepwise Precipitation

The Occurrence Behaviours of As/Sb/Bi in Copper Anode Slime and Their Separation by Compound Leaching Followed by Stepwise Precipitation

Extraction of Gold from the Leachate of Copper Anode Slime by Quaternary Ammonium Rice Husk Lignin

Extraction of Gold from the Leachate of Copper Anode Slime by Quaternary Ammonium Rice Husk Lignin

Selective Separation of Base Metals and High-Efficiency Enrichment of Precious Metals from Scrap Copper Anode Slime

Selective Separation of Base Metals and High-Efficiency Enrichment of Precious Metals from Scrap Copper Anode Slime

Immobilizing Sodium Arsenate from Lead Anode Slime as Crystalline Scorodite Using a Novel Multivalent Iron Source

Immobilizing Sodium Arsenate from Lead Anode Slime as Crystalline Scorodite Using a Novel Multivalent Iron Source

An innovative green process for separating and enriching tellurium from lead anode slime via vacuum gasification

Lead anode slime, which is produced by electrolytic refining of refined Pb, is a significant source of the rare metal Te. However, traditional methods for treating lead anode slime are characterized by complex processes, hazardous waste discharge, high energy consumption, repeated reduction and oxidation, and inefficient separation of Te. Therefore, a novel, green, and efficient vacuum gasification process for Te separation and enrichment was developed in this study. The optimal gasification temperature and time of Te volatilization were investigated using two-step, high-temperature and low-temperature vacuum distillation experiments; the system pressure was maintained at 5–15 Pa for both steps. Te (96.07%) in lead anode slime was separated using high-temperature vacuum gasification at 1173 K for 60 min and low-temperature vacuum gasification at 723 K for 45 min, yielding Te-rich volatiles with a 4.80% tellurium content. Te was enriched more than 16 times. Te existed as Te and TeO2 in the tellurium-rich volatiles, making the volatiles an excellent raw material for further tellurium purification. This two-step vacuum gasification process provides theoretical guidance for effective and sustainable recovery of Te from lead anode slime with no waste gas or water, which meets the need for cleaner production methods in the metallurgical industry.

Hydroxylation of electrolytic manganese anode slime with EDTA-2Na and its adsorption of methylene blue

Electrolytic manganese anode slime (EMAS) is a kind of waste produced by anode chambers in the process of electrolytic manganese production. In this study, the surface of EMAS was hydroxylated with EDTA-2Na, and a new adsorbent for removing methylene blue (MB) was obtained. The hydroxylation of EMAS (H-EMAS) was characterized by XRD, XRF, FTIR, BET, SEM and XPS. The results showed that H-EMAS contains many pores and cracks and that the specific surface area of H-EMAS was 53.17 m2/g. The maximum adsorption capacity of H-EMAS for MB was 70.74 mg/g when the initial pH was 6.00, the initial MB concentration was 500 mg/L, the reaction time was 120 min and the reaction temperature was 298 K. Adsorption kinetics and isotherms showed that the adsorption of MB on H-EMAS conformed to pseudosecond-order kinetic model and Langmuir isotherm, respectively. Thermodynamic analysis showed that the adsorption process was a spontaneous and exothermic physical adsorption process. Moreover, H-EMAS adsorbent recycling showed that the adsorption capacity of H-EMAS was 55.35 mg/g after four cycles and that the adsorption efficiency for MB only decreased by 21.75%. This study provides a new method for the resource utilization of EMAS.

Selective Separation and Recovery of Tellurium from Copper Anode Slime Using Acidic Leaching and Precipitation with Cuprous Ion

Selective Separation and Recovery of Tellurium from Copper Anode Slime Using Acidic Leaching and Precipitation with Cuprous Ion

Extraction of Gold from Gold Chloride Solution by the Depth Reduction Based on Potential Controlling in the Process of Treating Copper Anode Slime

Extraction of Gold from Gold Chloride Solution by the Depth Reduction Based on Potential Controlling in the Process of Treating Copper Anode Slime

Enhanced Leaching of Mn from Electrolytic Manganese Anode Slime via an Electric Field

Electrolytic manganese anode slime (EMAS) contains many Mn resources, and efficient Mn leaching is the key to realizing its high-value utilization. In this study, the effects of Fe2+ concentration,...

Copper Cathode Contamination by Nickel in Copper Electrorefining

Nickel behavior has a significant role in the electrorefining of copper, and although it has been extensively studied from the anode and electrolyte point of view over the past decades, studies on nickel contamination at the cathode are limited. In the current paper, three possible contamination mechanisms—particle entrapment, electrolyte inclusions and co-electrodeposition—were investigated. Copper electrorefining (Cu-ER) was conducted at the laboratory scale, and the cathodes were analyzed by scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS) and flame atomic absorption spectroscopy (AAS). Particle entrapment was studied by adding NiO and Fe2O3 to the system to simulate nickel anode slime, and the experiments were replicated with industrial anode slime material. The possibility of electrolyte entrapment due to nodulation was explored through the addition of graphite to produce nodules on the cathode. Co-electrodeposition was analyzed by experiments that utilized a Hull cell. The results indicate that particle entrapment can occur at the cathode and is a major source of the nickel contamination in Cu-ER, whereas nickel compounds were not shown to promote nodulation. Inclusions of bulk electrolytes within the surface matrix were observed, proving that electrolyte entrapment is possible. As co-electrodeposition of Ni in Cu-ER is thermodynamically unlikely, these experimental results also verify that it does not occur to any significant extent.

Recovery of Lead as Lead Sulphide from Anode Slime Using Hydrometallurgical Technique

Recovery of Lead as Lead Sulphide from Anode Slime Using Hydrometallurgical Technique

Modeling of Au Chlorination Leaching Kinetics from Copper Anode Slime

Modeling of Au Chlorination Leaching Kinetics from Copper Anode Slime

Size effect of γ-MnO2 precoated anode on lead-containing pollutant reduction and its controllable fabrication in industrial-scale for zinc electrowinning

Lead (Pb) is the most widely used anode in zinc (Zn) electrowinning and other metallurgical industries. The resource loss and environmental pollution caused by Pb anode corrosion are urgent problems to be solved. A γ-MnO2 precoated anode was prepared successfully to reduce the Pb-containing pollutant. The size effects with its controllable preparation on an industrial scale were studied. Severe nonuniform distribution of γ-MnO2 film was observed with curbing the reduction of anode slime only 68%, when anode size increased from lab to industry. Nonuniform rate (R) and average thickness (d) were found to be the key indicators to determine the film structure distribution and their performance differences, which were random and difficult to be controlled in scale-up size. However, a controllable industrial γ-MnO2 precoated anodes (IMPA) fabricated through optimized current density (J0) and electrodeposition time (t) in our developed film-forming system. Then, the long-term performances of two IMPA with different indicators (IMPA-1: R = 34%, d = 108 μm, IMPA-2: R = 23%, d = 55 μm) were compared with the industrial typical Pb-based anode (ITPA). Of the three different anodes, the optimized IMPA-2 displayed the best performance. Within 24 d of electrowinning cycle, the corrosion inhibition effect and the anode slime reduction rate for IMPA-2 improved by 56% and 30% than IMPA-1, and improved by 100% and 91% than ITPA. Furthermore, the mechanism analysis of size effect change showed that R of IMPA was contributed to the local gas holdup distribution along the anode. Controlled size effect of uniform oxide film will have a future application prospect for the sustainability of industry, which provides an important cleaner production of Zn electrowinning and related hydrometallurgy industries.