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Electrolytic refining
Abstract
Electrolytic refining is the principal method of mass-producing high purity (>99.97%) copper. The other is electrowinning. Copper from electrorefining, after melting and casting, contains less than 20 ppm impurities, plus oxygen, which is controlled at 0.018%–0.025%. Electrorefining entails electrochemically dissolving copper from impure copper anodes into an electrolyte containing CuSO4 and H2SO4, and then electrochemically depositing pure copper from the electrolyte onto stainless steel or copper cathodes. The process is continuous.
... However, during the process of purification, convex nodules and particles appear on the surface of the cathode copper plate. These nodules grow continuously and eventually make contact with the anode, resulting in a short circuit between the cathode and anode, which ultimately leads to a significant decrease in current efficiency and deterioration in the quality of the copper plate [1,2]. Current research indicates that the formation of nodules on copper cathode plates is caused by a combination of multiple factors. ...
Copper electrolysis is a crucial process in copper smelting. The surface of cathodic copper plates is often affected by various electrolytic process factors, resulting in the formation of nodule defects that significantly impact surface quality and disrupt the downstream production process, making the prompt detection of these defects essential. At present, the detection of cathode copper plate nodules is performed by manual identification. In order to address the issues with manual convex nodule identification on the surface of industrial cathode copper plates in terms of low accuracy, high effort, and low efficiency in the manufacturing process, a lightweight YOLOv5 model combined with the BiFormer attention mechanism is proposed in this paper. The model employs MobileNetV3, a lightweight feature extraction network, as its backbone, reducing the parameter count and computational complexity. Additionally, an attention mechanism is introduced to capture multi-scale information, thereby enhancing the accuracy of nodule recognition. Meanwhile, the F-EIOU loss function is employed to strengthen the model’s robustness and generalization ability, effectively addressing noise and imbalance issues in the data. Experimental results demonstrate that the improved YOLOv5 model achieves a precision of 92.71%, a recall of 91.24%, and a mean average precision (mAP) of 92.69%. Moreover, a single-frame detection time of 4.61 ms is achieved by the model, which has a size of 2.91 MB. These metrics meet the requirements of practical production and provide valuable insights for the detection of cathodic copper plate surface quality issues in the copper electrolysis production process.
Clean energy infrastructure depends on chalcopyrite: the mineral that contains 70% of the world’s copper reserves, as well as a range of precious and critical metals. Smelting is the only commercially viable route to process chalcopyrite, where the oxygen-rich environment dictates the distribution of impurities and numerous upstream and downstream unit operations to manage noxious gases and by-products. However, unique opportunities to address urgent challenges faced by the copper industry arise by excluding oxygen and processing chalcopyrite in the native sulfide regime. Through electrochemical experiments and thermodynamic analysis, gaseous sulfur and electrochemical reduction in a molten sulfide electrolyte are shown to be effective levers to selectively extract the elements in chalcopyrite for the first time. We present a new process flow to supply the increasing demand for copper and byproduct metals using electricity and an inert anode, while decoupling metal production from fugitive gas emissions and oxidized by-products.
With the gradual decrease in the grade of copper ores being processed, copper concentrates have become more complex with higher impurity and gangue content. This trend has had a detrimental effect on smelters as they have to increase throughput to maintain copper metal production, while increasing operating costs due to processing the increased amounts of secondary products (slag, acid) and stabilizing waste streams. This paper discusses impacts from the increased complexity of resources from mine to smelters, highlighting the need for an integrated processing approach to achieve sustainable and competitive multi-metal recovery.
Anode slimes resulting from the electrorefining of Cu, Pb, Sn, and Zn contain noble metals, such as Au, Ag, and platinum group metals. Pretreatments have been employed to enrich the noble metals by removing base metals from the anode slimes. The enriched residues are dissolved in diverse aqueous systems such as cyanide, thiosulfate, thiourea, and halide in the presence/absence of oxidizing agents. Separation of noble metals from the solution depends on the nature of the leaching solutions. Solvent extraction, ion exchange, electrowinning, and some novel technologies are employed for the separation. The advantages and disadvantages of each separation process were reviewed. Moreover, new materials for the separation of noble metals have been introduced.
Ion exchange has traditionally been employed for water purification and the removal of metal contaminants from dilute waste streams. More recently, its use in removing trace metallic impurities from hydrometallurgical process streams (with typical background metal concentrations of 50–100 g/L) has increased substantially. It is also used as a primary recovery and concentration unit operation for certain commodities, where both technical and cost advantages become apparent for complex flow-sheets. This overview discusses selected modern applications of ion exchange in hydrometallurgical processes for uranium, precious metals, copper, cobalt, nickel, zinc, and the rare-earth elements, and identifies some opportunities for the future.
This article presents the results of a three year research project funded by the “Sponsor Group Cop-per Electrorefining”. Investigated were passivation behaviour, anode dissolution, anode sludge for-mation and distribution coefficients of impure copper anodes with linear independent target con-tents of Sb, As, Bi and O processed at three current densities. The experimental setup is shown as well as the obtained results. Mathematical modelling of the results was done, analysing the influence of these factors and their interdependencies on the electrolysis process. All significant effects are displayed using scaled and centred coefficient plots describing the influence of the critical elements.
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Tellurium is a rare metalloid that is vastly produced from copper anode slime, which is a by-product of the copper electrorefining process. Choosing the proper recovery method strongly depends on the slimes composition, mineralogy, and tellurium concentration. In addition, correctly selecting the right method of leaching, purification, and precipitation in economic and environmental processing of the variety of copper anode slimes very much depends on having a thorough understanding of the chemistry, thermodynamics, and kinetics of the recovery process. Despite a wide variety of developments in the recovery of slime, a lack of comprehensive study to help identify the effective factors in the selection of the right process is evident. This article provides a comprehensive literature review on the available tellurium recovering processes from copper anode slime to the final high purity product. This overview is written, hoping to help researchers select and apply the appropriate method in the recovery of tellurium from copper anode slimes of different characteristics.
In order to recover gold and silver from anode slimes containing Cu, Ni, Sn, and Zn, an integrated hydrometallurgical process consisting of leaching, solvent extraction, and cementation was developed. All the metals together with 10% of Ag(I) were dissolved by the mixture of HCl and H2O2 at the optimum conditions. Separation of Au (III) together with Sn (II) was performed by Cyanex 272 from the leaching solution with two-stage counter current extraction. Stripping of Au (III) and Sn (II) from the loaded organic phase was sequentially carried out by NH4Cl and NaOH. Cu (II) in the raffinate after Au (III) extraction was separated by LIX 63 with three-stage counter current extraction. Pure Cu (II) solution was recovered from the loaded LIX 63 by stripping with dilute HCl solution. Ag powders with extra high purity were obtained by cementation with copper sheet from the raffinate after Cu (II) separation. Au (III) (99.3%) and 96.8% of Sn (II) were recovered by extraction, and purity of Au (III) and Sn (II) stripping solutions was found to be 99.99%. Au powders with extra high purity were directly synthesized by adding ascorbic acid solution into the NH4Cl stripping solution.
Antimony and bismuth are two of the most problematic impurities in copper electrorefining. As a result, much research has been done investigating the ways to remove them. Processes that are currently being used industrially include anode additions, liberators, ion exchange (IX), and solvent extraction (SX). Of these, liberators and anode additions are the most common while SX is the least, mostly being used for arsenic removal. Other methods have been evaluated, but they are not in commercial use. These include the use of various electrolyte additives, as well as adsorbents such as bentonite clay and heavy metal sulfates.
The METTOP-BRX-Technology is a new electrolysis technology that can be applied in existing and new tankhouses. It uses a parallel electrolyte flow to achieve high current efficiencies, even at high current densities. In the last years, the METTOP-BRX-Technology has been tested in different types of tankhouses, and also half of the new tankhouse at Montanwerke Brixlegg AG, Austria, was equipped with this new technology in 2007. The newest development for the installation of the METTOP-BRX-Technology in existing tankhouses is the so-called Internal Loop (IL). The IL is a new piping solution that minimizes the installation costs of the METTOP-BRX-Technology in an existing tankhouse. With the IL, the existing piping can be used and shut downs during installation can be avoided. The latest big success of the METTOP-BRX-Technology was the decision of Xiangguang Copper, China, in 2009 to install the METTOP-BRX-Technology in all 720 cells of the new tankhouse – the designed current density is 410 A/m² and the tankhouse has being specially designed for the new technology.
Atlantic Copper is a copper cathode producer located in Spain. One of the most important steps in the production process is electrorefining, and this is strongly influenced by elements dissolved in the electrolyte. The presence of some metals or semi-metals, such as As, Sb or Bi, adversely affects the current efficiency and quality of the cathodes. Therefore, it is very important to control the level of such impurities in the electrolyte. This paper describes the study of the separation of Sb and Bi from a real electrolyte by means of ion-exchange columns (using aminophosphonic resins). Possible variations of the composition of the electrolyte were considered, because the presence of Fe(III) could poison the resins. Thus, the main result of the work is a complete operating protocol (load + elution + regeneration) of ion-exchange columns. Different alternatives to resin regeneration are also described in order to adapt the designed installation to the variability of Sb, Bi and Fe impurity levels in the electrolyte.
Porphyry copper and mixed copper-gold sulfide deposits contain varying amounts of precious (gold and silver) and platinum group metals (PGMs). Currently, milling and froth flotation is the most common processing route for the treatment of high-grade base metal sulfide ores. During this process, the precious metals and PGMs are also concentrated and represent a possible opportunity for the beneficiation of these metals to increase the overall economic value of the ore. Although not yet commercialized, the high temperature pressure oxidation (POX) of copper concentrates provides an alternative processing route to traditional smelting technology. With increasingly aggressive air quality standards and rising upstream processing costs for smelting, hydrometallurgical processing options become progressively attractive. The treatment of POX residues for the recovery of precious metals has seen significant attention and multiple processing routes have been developed on various scales. Extraction and beneficiation of PGMs from copper concentrate POX residue has garnered significantly less attention and mechanistic questions remain to be answered. Based on a review of the processing options for PGM ores and concentrates, hydrometallurgical processing routes for the extraction of PGMs from copper concentrate POX residues are envisioned.
In copper (Cu) smelters, precious metals in recycled materials are distributed into electrolytic Cu slime. During the precious metal refining process, rhodium (Rh) and ruthenium (Ru) are concentrated from the slime into residues containing selenium (Se) and tellurium (Te). In this study, new methods were developed for refining Rh and Ru by obtaining aqueous solutions of Rh and Ru and separating Se and Te using a hydrometallurgical process followed by a pyrometallurgical process. In the hydrometallurgical process, Se and Te are dissolved by air oxidation in a sodium hydroxide (NaOH) solution, and Cu is dissolved using diluted sulfuric acid (H2SO4). Se and Te are removed by dissolution and separated from the undissolved Rh and Ru. In the pyrometallurgical process, the residual Se and Te in the Rh and Ru concentrates obtained from the hydrometallurgical process are chlorinated and separated by volatilization. Rh, Ru, Se, and Te are chlorinated by heating to 1000–1100 K in chlorine (Cl2) gas. Volatilization was used for separation of Se and Te from Rh and Ru because the vapor pressures of Se and Te chlorides are higher than those of Rh and Ru chlorides. Because the chlorides of Rh and Ru have poor solubility, they are mixed with sodium chloride (NaCl), heated, and converted to soluble complex salts containing Rh and Ru, which are later dissolved in water to obtain an aqueous solution containing concentrated Rh and Ru.
The toxicity of arsenic is well known and documented; however, the presence of arsenic
in copper electrorefining anodes and electrolytes is critically necessary to produce high-quality cathode.
Arsenic as well as antimony and bismuth concentrations vary relative to their concentration in the anode
copper received from the smelter. The behaviour and benefits of arsenic in copper electrorefining and the
detrimental effects of antimony and bismuth on cathode quality and tankhouse performance are discussed. This will include the minimization and mitigation of problems associated with arsenic, antimony,
and bismuth—including cathode contamination, floating slimes, scaling, and anode passivation
Copper electrorefining tests were conducted in a pilot-scale cell under commercial tankhouse environment to study the effects of anode compositions, current density, cathode blank width, and flow rate on anode slime behavior and cathode copper purity. Three different types of anodes (high, mid, and low impurity levels) were used in the tests and were analyzed under SEM/EDS. The harvested copper cathodes were weighed and analyzed for impurities concentrations using DC Arc. The adhered slimes and released slimes
were collected, weighed, and analyzed for compositions using ICP. It was shown that the lead-to-arsenic ratio in the anodes affects the sintering and coalescence of slime particles. High current density condition can improve anode slime adhesion and cathode purity by intensifying slime particles’ coalescence and dissolving part of the particles. Wide cathode blanks can raise the anodic current densities significantly and result in massive release of large slime particle aggregates, which are not likely to contaminate the cathode copper. Low flow rate can cause anode passivation and increase local temperatures in front of the anode, which leads to very intense sintering and coalescence of slime particles. The results and analyses of the tests present potential solutions for industrial copper electrorefining process.
During the electrorefining of copper anodes, gold shows a strong affinity for selenium. In the raw anode slimes, gold occurs mainly as tiny metallic gold particles which are commonly attached to larger selenide particles. Decopperizing of the anode slimes retains much of the metallic gold, but also promotes the incorporation of gold in silver selenide. A greater fraction of the gold is converted to (Ag,Au)2Se or Ag3AuSe2 when high-Se and high-Ag anode slimes are decopperized at elevated temperatures and pressures. After pelletization and roasting of the decopperized slimes, the gold is converted to a (Ag,Au)-alloy and Ag3AuSe2. Smelting of the roasted products eliminates the selenium and converts the gold to a silver-rich (Ag,Au,Pd)-alloy in the Dore metal. In the subsequent silver electrorefining process, gold collects as a gold-rich (Au,Ag,Pd)-alloy in the gold mud.
With the ever-increasing demand for higher purity electrorefined and electrowon copper, and the desire to improve productivity by increasing current densities, the control of addition agents for grain refining and levelling cathodic copper deposits has become imperative. Historical practice had been to supply agents at constant rates and to adjust such rates through trial and error based on the morphology of copper being produced. This paper reports the successful results of employing cyclic voltammetry to monitor twice weekly the “suitability” of glue and Tembind (a lignosulfonate) additions at Inco's Copper Cliff Copper Refinery.
As commercial copper electrorefineries look to expand their capacities by increasing their operating current density, the likelihood of anode passivation intensifies. To improve the industry's understanding of the passivation phenomena, the role of anode composition was evaluated. While previous studies have focused on studying one impurity element at a time, this study was conducted using forty-four commercial electrorefining anode samples supplied by ten copper companies The passivation response of each sample was evaluated under accelerated galvanostatic conditions in synthetic copper electrowinning electrolyte at 65°C. This information allows for correlations between composition and passivation tendencies over a wide range of impurity elements and concentrations. It was found that selenium, tellurium, silver, lead and nickel accelerated passivation. It appeared that oxygen accelerated passivation when increased from 500 to 1500 ppm, but further increases did not have an effect. Arsenic was the only impurity found that inhibited passivation.
Effective removal of bismuth is a primary concern during copper electrorefining. A novel electrowinning process using an emew® cell was developed to recover bismuth and copper from a copper electrorefining waste stream. Significant removal and co-deposition of copper and bismuth were achieved from a highly acidic sulfate industrial effluent using a current density of 350 A/m2, but the current efficiency was low (27%). Operating at a lower current density (75 A/m2) facilitated the preferred removal of Cu, while increasing current efficiency to 67.4% due to the enhanced mass transport and decreased side-reaction. Consequently, a two-stage emew® cell process was employed to remove most of the copper at low current and then extract bismuth at high current. 93.4% of the bismuth and 97.8% of the copper were recovered with a satisfactory current efficiency, and a high purity (~98%) Bi powder was obtained in the second step. This novel emew® cell approach may serve as a promising alternative for the recovering of copper and bismuth, and the proposed two step strategy may offer insight for the selective recovery of metals in a multi-component system.
Many factors which affects the anode passivation during electrolysis were discussed in this paper. These includes the amount of slime and slime adhesiveness. The internal factors which affects the amount of slime include the type, concentration and the form of impurities which exists in the anode. The external factors include the concentration of the dissolved oxygen and the impurity ions in electrolyte or the electrolytic condition such as current density.The anode impurities showed different behaviour of dissolution state according to the various forms of existence and the varying chemical properties of these elements or compounds. The anode slimes are formed either by dissolving of these impurities in the electrolyte at the anode or by remaining on the anode surface. The amount of these slimes greatly affects the occurence of passivation.It was clarified that the coexistence of oxygen together with elements such as S, As and Bi in anode affects the amount of slime, adhesiveness and therefore also affects passivation. The possibility of passivation increased markedly with increasing current density, dissolved oxygen, impurity ions, as well as the concentration of H2SO4.
The interaction between chloride and thiourea in copper electrodeposition in a sulfate-plating bath was investigated. The sole addition of thiourea to the bath increased the polarization of the electrode potential during copper deposition, leading to very fine and smoothly structured deposit but with microscopic nodules distributed over the surface. When chloride was added to a plating solution containing thiourea, the copper deposition mechanism was changed, showing a depolarization of the electrode potential, and the copper deposits were found to have a relatively rougher microstructure, but without the formation of microscopic nodules. However, rough deposit surfaces having no distinct pattern were formed at the macroscopic scale. Observations of roughening evolution show that the rough surface was initiated from small holes formed across the deposit surface during the initial stage of deposition that eventually developed into visibly rough deposits. The copper deposition inside these holes and at other areas was expected to undergo different deposition mechanisms. Copper deposition in the areas that ultimately developed into holes was almost totally inhibited by the thiourea–Cu(I)–chloride complex film, not just in the grain growth process, but over practically the entire electrodeposition process. Conversely, copper deposition occurred in other areas under conditions where nucleation proceeded, but grain growth was inhibited to produce a fine, homogeneous microstructure. An uneven deposit surface that had different microscopic structures in different areas was then formed. The structure of the thiourea–Cu(I)–chloride film was strongly affected by the current density and appeared to break down completely if sufficiently high current density was applied to yield a fine and homogeneous microstructure that was also macroscopically smooth.
Antimony- and bismuth-rich copper anodes, anode slimes and decopperized anode slimes from industrial copper electrorefineries were studied mineralogically. Antimony in the anodes occurs mainly as Cu-Pb-As-Sb-Bi oxide inclusions along the copper grain boundaries; bismuth is mainly present as Cu-Pb-As-Sb-Bi oxide, Cu-Bi-As oxide, Cu-Pb-As-Bi oxide and Cu-Bi oxide inclusions. Sb and Bi partly dissolve during electrorefining, but extensively reprecipitate as As-Sb oxide, As-Sb-Bi oxide and SbAsO4. The presence of As results in the precipitation of essentially all the Bi as BiAsO4. The decopperizing process dissolves much of the Sb and Bi, although the majority of the BiAsO4 phase remains unaffected. Subsequently, some of the dissolved Sb and Bi reprecipitates as various oxide, sulphate and arsenate species. X-ray absorption near-edge structure (XANES) analyses suggest about 70% of the antimony in the anode slimes is present in the pentavalent oxidation state. The XANES analyses indicate that most of the Bi in all the slimes samples is present in the trivalent oxidation state.
In the present research, an effort has been made to prepare copper salt/powder from the copper bleed stream generated during the electrowinning of pure copper from the copper anode in a copper smelter. Various approaches have been opted for the complete recovery of copper values such as: evaporation–crystallization, electrolytic process, and direct hydrogen reduction. Physical and chemical properties of copper powder/salt produced from the large-scale experiments from actual plant and model solutions have been evaluated for P/M applications and compared with the standard properties. Thus, mixed crystal suitable for recycling back to the system as a makeup salt containing nickel in a tolerable range could be recovered by evaporation and crystallization of the bleed stream up, to 50%. Copper powder recovery by the electrolysis process at a current density of 700 A/m was about 95%. Scanning electron microscope examination showed that the powder was dendritic in nature. On annealing, the purity of the copper powder was found to be 99.95%. The annealed powder had apparent density of 3.04 g/cc, hydrogen loss 0.72%, and acid insoluble as 0.27%. On compaction of 99% and the annealed powder had an apparent density of 3.50 g/cc, flow rate 35.6 g/min, hydrogen loss 0.195%, purity 99.8%, and green density of 8.57 g/cc while the powder from the actual plant solution was found to have an apparent density of 3.49 g/cc, flow rate 46.0 g/min, hydrogen loss 0.598%, purity 99.4%, and green density 8.57 g/cc for the powder
When nickel concentration increases in the copper sulphate electrolyte during electrolysis, it starts electrodepositing on the copper cathode thereby affecting the purity of the copper. In order to produce high quality copper cathodes with less than 1 ppm Ni, it became necessary to bleed-off large volumes of foul electrolyte contaminated with nickel and other impurities. The study reported in this paper was part of the effort aimed at devising a cost effective and an ecofriendly method for the production of value added powders from a waste stream, for P/M application. A part of copper salts and regenerated acid was used back into the system. As discussed in our paper on copper recovery from copper bleed stream (CBS), a process involving decopperisation and crystallisation–solvent extraction (SX) separation–electrowinning (EW) has been attempted as an alternative to the conventional process. Optimum conditions for nickel recovery from this type of solution have been investigated through a series of experiments carried out in a rectangular electrolytic bath with SS as cathode and Pb–Sb as anode. A quantitative and selective recovery was found for nickel deposition under suitable conditions. The purity of the electrolytic nickel powders so produced was found to be 99.89%. The compact density of the annealed nickel powder was 7.72 g/cc. Other properties of the nickel powders such as flow-ability, particle size, etc. were also evaluated to assess its suitability for its use in P/M applications.
Most by-product gold comes from the processing of copper refinery anode slimes that are generated during the electrorefining of copper anodes. In the copper anodes, the gold occurs in solid solution in the copper crystals. During electrorefining, the copper dissolves and the associated gold is released. Some of the gold reports as tiny metallic gold particles in the anode slimes. The gold shows a strong affinity for the selenide phase, and some of the metallic gold nucleates on the selenide particles. Some gold also appears to dissolve in the sulfate electrolyte, possibly because of the presence of chloride and thiourea. The dissolved gold subsequently precipitates as a minor constituent of a complex oxidate phase and reacts to form a solid solution in the selenide phase and a discrete Ag-Au-Cu selenide phase. Decopperizing of the anode slimes concentrates the gold as metallic gold and an Ag-Au selenide phase (Ag3AuSe2). The metallic gold shows a strong affinity for selenium, and the Ag-Au selenide phase appears to form during decopperizing, becoming prevalent under high-temperature and pressure-leaching conditions. Also, the silver selenide phase becomes enriched in gold.
The effect of trivalent arsenic on the removal mechanism of antimony and bismuth from copper electrolyte was investigated. The electrolyte was filtered and the precipitate structure, morphology and composition were analyzed by means of chemical analysis, scanning electron microscopy, transmission electron microscopy, energy dispersive spectra, X-ray diffraction, and infrared spectroscopy. The precipitate in the form of fine spherical particles mainly consists of As, Sb, Bi and O elements. The characteristic bands in the IR spectra of the precipitate are O–H, As–OH, As–OX (X = As, Sb), As–O–Sb, Sb–OY (Y = As, Sb, Bi) and O–As–O. The precipitate is a mixture of microcrystalline (Sb, As)2O3, BiSb2O7, and an amorphous phase. The impurities of Sb and Bi are effectively removed from copper electrolytes by trivalent arsenic owing to these precipitates.
Extractants and processes used and proposed for recovery of arsenic, antimony and bismuth from copper electrolytes are presented and discussed. The use of the following extractants is duscussed: tributyl phosphate, partial esters of phosphoric acid (mono(2-ehtylhexyl)phosphoric acid, bis(2-ethylhexyl)phosphoric acid and mono(isooctadecyl) phosphoric acid, - DS 5834), esters of alkylphosphonic acids, trialkylphosphine oxide, CYANEX® 923 extractant, hydroxamic acids, LIX 1104, alcohols (2-ethyIhexanol and others), hydrophobic diols and alkylpolyphenols. The chemistry and processes are presented and discussed.
A couple of refineries have adopted the solvent extraction (SX) process in place of the electrolytic route which is commonly employed for the purification of copper electrolyte with respect to various impurities. The SX process based on TBP (Tri n-Butyl Phosphate) solvent is particularly effective in the separation of arsenic from the electrolyte. Also, an ion-exchange (IX) process using a chelating resin, has been developed and employed in three other refineries for the removal of antimony and bismuth impurities from the electrolyte through preferential adsorption.The paper presents the results of the experimental studies as well as of the operation trials conducted in these refineries on the purification of the copper electrolyte by the removal of Va group elements employing the SX and IX processes. The paper also discusses the details of the investigations carried out on a} the revovery of TBP from the extraction raffinate by scrubbing with carbon tetra chloride, b) preferential sulfidation of copper in arsenate solution, c) the recovery of arsenic tri-oxide powder by freeze-melt technique, d) development of a closed circuit stripping system involving regeneration of ammonia by addition of lime to NH3-(NH4) 2, S04 stripping solution and e) the cyclic use of HCl-NaCl eluant in a chelating resin process of regeneration of HCl.
Bleed stream from electro refining step of copper smelter was processed to recover the metals as high value products such as copper and nickel powders or salts. The process consists of partial decopperisation of the bleed stream followed by crystallization of a mixed salt of copper and nickel sulphate, leaching of the mixed salt, removal of iron, solvent extraction for the separation of copper and nickel and winning the solution to produce metal powders. After partial decopperisation of copper bleed stream, the resultant solution was subjected to crystallization which produces composite crystals with the chemical composition of 8.4–12.5% Cu, 13.7–14.38% Ni and 1–2 ppm of Fe as impurity. This mixed salt was leached with water and was treated for iron precipitation. The purified solution was subjected to solvent extraction using two solvents namely LIX 84 or Cyanex 272. A 20% LIX 84 in kerosene extracted 99.9% copper and 0.059% nickel at a pH of 2.5, similarly a 5% Cyanex 272 in kerosene extracted 98.06% copper and 0.51% nickel at a pH of 4.85. LIX 84 was used for metal separation in the mixer-settler unit and a flow sheet was developed using this solvent. The pure solutions of copper after stripping it from the loaded organic and nickel left in the raffinate were further electrolysed to produce pure copper (99.9%) and nickel (99.8%) powders, alternatively pure sulphate salts could also be crystallized. Since it is well known that Cyanex 272 is used for the separation of cobalt and nickel, a few experiments were performed on the extraction of copper by using Cyanex 272. A complete study is yet to be done to develop a flow sheet by using this solvent.
Densities, viscosities, electrical conductivities and specific heats of solutions containing copper, nickel, arsenic, iron
and sulphuric acid in the concentration ranges of copper electrorefining and electrowinning electrolytes have been measured.
Equations are presented for calculating these properties as a function of electrolyte composition and temperature.
The phrase “purification of copper refinery electrolyte” is misleading since typically, impurities are controlled by withdrawing
a bleedstream of the circulating electrolyte. However, solvent extraction and ion exchange have also found some application
in impurity control. This article describes conventional practice, including treatment of the bleedstream, and other attempts
at electrolyte purification. Impurities to be discussed include Sb, Bi, As, Ni, Ca, ammonia, and organic fragments generated
from hydrolysis of conventional cathode growth-modifying addition agents.
The development of the CollaMat glue measuring system started at Norddeutsche Affinerie (NA) in 1986. Since 1989, CollaMat
has been used for continuous glue measuring in NA’s copper tankhouse. In addition, the system is used under license worldwide
in ten tankhouses. This paper provides an overview of basic CollaMat investigations in the laboratory as well as NA experiences
in the production plant.
Nickel-bearing copper anodes and anode slimes were studied using a variety of mineralogical and chemical techniques. In anodes
containing <;0.3 pct Ni, the nickel occurs only in solid solution in the copper matrix. This nickel dissolves simultaneously
with the copper during electrorefining, but a small amount reprecipitates as copper-nickel sulfate or a complex Ni-bearing
Cu-Ag-As-Se-S oxidate phase in the anode slimes. In anodes containing >0.3 pct Ni, NiO crystals also form. The presence of
the Cu-Ni-Sb oxide, kupferglimmer, in the anode depends on its antimony content. Kupferglimmer is prevalent in nickel-rich
anodes with high Sb contents (>200 ppm) but is not found in similar anodes with Sb contents <200 ppm. Various Cu-Ni and Ca-Cu-Ni
silicate inclusions are present. Depending on the iron content of the anode, Fe-bearing NiO, NiFe2O4, and other Ni-bearing iron oxide phases also may be present. All of the oxidate nickel phases remain largely undissolved
during electrorefining and concentrate in the anode slimes.
Copper bleed solution generated from an Indian Copper smelter contains high amount of copper and nickel along with several impurities. Attempts have been made to develop a new process for the production of pure copper powder from such streams. The purity of the electrolytic copper powder produced from such bleed streams was found to be 99.93%. Properties such as compact density of the annealed copper powder, flow-ability, particle size, etc. were evaluated and were found to be suitable for the powder metallurgical applications.
A mineralogical study of anode passivation in copper electrorefining
- Chen
Electrorefining high level arsenic cast anode
- Atenas
The behaviour of tellurium during the decopperizing of copper refinery anode slimes
- Chen
Latest development in cathode stripping machines
- Larinkari
The role of electrolyte additives on passivation behaviour during copper electrorefining
- Moats
Problems in the electrolysis of copper anodes with high contents of nickel, antimony, tin and lead
- Mubarok
Anode slime leaching and tellurium removal at Atlantic Copper refinery
- Ramírez
Processing of copper electrorefining anode slimes: A review
- Hait
The historical development of electrolyte additives and their specific role and influence on cathode quality
- Hiskey
Advanced wireless monitoring and integrated information management for improving electrorefinery performance
- Rantala
Upsets on antimony contents in electrolytic copper produced at Caraiba Metais
- Santos Moraes
High current density operation at Toyo tankhouse
- Takenaka
Processing high nickel slimes at CCR refinery
- Doucet
Utilizing ion exchange for impurity control in copper electrolyte
- Elkayar
Current density increase within the last 150 years
- Filzwieser
Applications of Lateralvex® and Lateralflow® technologies in Minera Antucoya, an AMSA tank-house in Chile
- Penna