12th International Copper Conference

Table of Contents

1. Electrowinning and Electrorefining

   1. Frontmatter

   2. Advancements in Metal Concentration Monitoring: Enhanced Copper and Nickel Measurement in Electrometallurgy Processes for Process Control

      Andrew Yang, Brane Pesic, Tony Mathison

      Abstract

      Current-day electrolysis operations need to adapt to complex ore grades with high impurity levels. The Mipac Metal Concentration Monitor system has undergone significant enhancements to address the evolving challenges in copper (Cu) hydrometallurgy and electrometallurgy, with promising results for the nickel (Ni) sector. The first-generation system uses optical spectroscopy, eliminating the need for online process analyzers that rely on chemical reagents for analysis and specialized laboratory expertise. The upgraded system continues to use optical spectroscopy, with the recent advancements enabling absorbance measurements of the electrolyte solution at two distinct wavelengths for determination of Cu and Ni concentrations. Ni can often present as a dominant impurity in Cu electrorefining, and the ability to measure Ni concentrations online could provide significant production insight for operations. Absorbance spectroscopy measurements showed the characteristic overlapping wavelengths for Cu and Ni, leading to interference during measurement at higher concentrations of Ni. To address this issue, a novel correction algorithm was devised, leveraging the multiple wavelength absorbance data to accurately discern and isolate the contributions between Cu and Ni. The enhanced system retained the previous system’s accuracy, however was still sensitive for some test results. This was likely because of some absorbance of other dissolved species in the Cu electrolyte at the two distinct wavelengths.

   3. Development Trend of Equipment Used in Copper Electrorefining Tankhouses in China

      Chi Zhang, Junyi Wu

      Abstract

      This paper introduces the equipment used in the tankhouses of China’s copper refining industry in recent years and looks ahead to the future demand features and the trend of new equipment that the copper refining tankhouses hope to use. After the large-scale capacity investment and construction in the past two decades, the problems faced by China’s copper refining tankhouses are no longer just how to increase output, but how to deal with the latest issues brought about by the massive production to further improve production efficiency and competitiveness. The instability of raw material supply leading to unstable production quality; higher requirements for health, safety, and environment in production operation; and the difficulties in implementing full-process management across whole operation process in practice, these new problems have led to the demand for new equipment in tankhouses. There are already many Chinese copper refineries that have started using automated logistics system such as AGV, RGV, and stereoscopic warehouses to transport the cathodes and anodes; tankhouses are also increasingly adopting inspection equipment to monitor their production processes in real time and improve the quality of the final products, as well as the efficiency of the production; the upgrades of existing operating equipment, such as permanent cathode plates and robotic striping machines, are also ongoing. This paper describes in detail the recent appearance of these new equipment and the functions they achieve and the value they bring, the development trends of them reflect the common demand for higher levels of automation, digitalization, and intelligentization in copper electrorefining tankhouses.

   4. Evaluation of Permanent Cathode Technology for Copper Electrowinning at Rustenburg Base Metals Refinery

      Kalin Naidoo, Max Pelser, Justin Hagemann, Kathryn C. Sole

      Abstract

      Significant advantages of permanent cathode technology have been demonstrated for copper electrowinning. The copper starter-sheet operation at Rustenburg Base Metals Refinery is labour-intensive, and performance is heavily dependent on structural integrity and equipment reliability. The viability of sustainably converting this low current density operation to use of permanent cathodes was evaluated. An 18-harvest cycle pilot trial was carried out under existing plant operating conditions to assess the ability to consistently produce good quality copper. This paper describes the testwork results, including the installation of new cell-top furniture and busbars. Good quality copper was produced from standard (low) current density (<150 A/m²) cycles; unfavourable results were observed during higher current density cycles (290 A/m²). Up to 92.5% current efficiency was achieved, with minimal scrap production. For the current electrolyte composition, the operational current density, size of Pb–6%Sb anodes, type of cathode edge strips, effect of over-plating, and the use of fibreglass electrode-stabilising plates installed at the base of the electrowinning cells proved to be important conversion considerations.

   5. Bismuth and Antimony at Olympic Dam: The Connection Between Orebody Knowledge and the Copper Refinery

      Vanessa Liebezeit, Kathy Ehrig, Peter Dospisil, Elise Naumann

      Abstract

      The Olympic Dam operation consists of an underground mine, mineral processing plant and copper smelter and refinery. The Olympic Dam breccia-hosted Fe-oxide Cu-U-Au-Ag (IOCG) deposit is, like all ore deposits, zoned with respect to the ore, gangue and deleterious/sub-economic minerals. This zoning can also be further disrupted by significant post-mineralisation vertical faulting. Short-range variability from drill core to blast packet to production stope and mine area scale typifies the deposit. Often, geometallurgy is associated with mill throughput or flotation recovery; however, the vertically integrated operation means that the geometallurgy program must consider all minerals and elements which affect the mills, concentrator, hydrometallurgy plant, smelter and ultimately the copper refinery. During an extensive drilling and testing program in the Southern Mine Area of the deposit, an area of higher bismuth (Bi) and antimony (Sb) was identified. Using a combination of mineralogy and metallurgical testwork, the geometallurgy program predicted the levels of Bi and Sb in concentrate would significantly increase on historic levels and would likely exceed the level that the existing refinery impurity removal system could manage. Therefore, a project was initiated to add a Bismuth and Antimony Removal System (BARS) to the refinery based on ion exchange technology. This system was commissioned in 2023. This paper describes the focus of our geometallurgy program on deleterious elements which affect the refinery and copper cathode quality, discusses impacts on the refinery of elevated Bi and Sb as we began mining in the SMA, and presents early results from the new removal system.

   6. Copper Electrowinning: 2025 Global Survey of Tankhouse Operating Practice and Performance

      Kathryn C. Sole, Tyler McCullum, Andrew Nisbett, Jacklyn Steeples, Michael S. Moats

      Abstract

      Global practice in copper electrowinning is reviewed, based on individual plant operating data for 2024. Data from 32 operations in the USA, Chile and Peru, African Copperbelt, Indonesia, and Kazakhstan were supplied, representing 41% of 2024 global hydrometallurgical cathode production and 68% of world copper tankhouse capacity. Evolving trends in operating conditions and performance, as well as equipment design and process technology choices, are assessed. Initiatives and operating preferences to increase productivity, improve copper quality, and decrease electrical energy consumption are discussed. Global best practice with respect to the main productivity and quality drivers is summarized.

   7. Simplification of Battery Metal Flow Sheet Using Electrolysis for Selective, Direct Copper Recovery

      A. Mishra, K. Melana, E. Saavedra

      Abstract

      Laboraroty and Pilot trials was completed at Chesils Electro Refinery, India to directly de-copperize the high nickel electrolyte without any IX/SX and to produce a high purity, harvestable copper cathode to low copper concentrations. The laboratory trials were conducted on 1-cell laboratory skid and pilot trial was on a 2-cell emew skid, using the commercial size emew cells. The trial results demonstrated that copper can be depleted very selectively from >35 g/L to <5 g/L using emew cells in the presence of >50 g/L nickel with no nickel deposition. The harvested copper cathode was coherent and has a purity of >99.99% without any dendrite/nodule formation or powder/cake formation, while operating at current densities in the range of 200–550 A/m^2. Further depletion of copper to lower concentrations (<50 ppm) was also demonstrated in the laboratory trials using a 3D cathode design. The pilot results confirm that extremely selective, direct copper metal production is possible from nickel streams, offering a sustainable and simpler flow sheet to recover battery metals while increasing the copper circularity.

   8. Improvements Made to Increase the Recycled Raw Material Processing Rateat Tamano Refinery

      S. Aoki, M. Narita, Y. Nishi, R. Takeuchi

      Abstract

      Tamano Smelter and Refinery of Hibi Kyodo Smelting Co., Ltd. was established in 1968 and started its operation at the Tankhouse No.1 in 1972 and at the Tankhouse No.2 in 1984.

   9. Initiatives to Treat Impurity Elements at Saganoseki and Hitachi Refinery Toward “Green Hybrid Smelting” in JX Advanced Metals Corporation

      Jun Kawashima, Satoru Nagao, Atsuki Sado, Keitaro Koga, Akira Ueno

      Abstract

      A stable copper supply is needed to meet the increasing copper demand, which is expected to continue growing in the future. Moreover, a copper refining process with a lower environmental burden is required. JX Advanced Metals Corporation aims to establish a stable copper supply system and lower the environmental burden of copper production. To achieve this goal, we are developing “Green Hybrid Smelting” process that maximizes the processing of secondary raw materials by efficiently utilizing the flash smelting process. Notably, impurities such as nickel, antimony, and bismuth contained in the secondary raw materials deteriorate the quality and efficiency of copper production during the electrorefining process. Herein, we reinforced the capacity of nickel, antimony, and bismuth removal at the Saganoseki and Hitachi Refinery. The series of process reinforcement allows us to maintain the high quality of copper during electrorefining, even when the impurity load increases. We plan to further reinforce our impurity removal capacity to increase the ratio of the secondary raw materials in the feed to 50% by 2040.

   10. Use of Monolithic Cell Liners for Recovery and Performance Improvement of Damaged Cells, Codelco Chuquicamata Refinery

       Marco Cifuentes, David Ferrada, Pablo Sanzana

       Abstract

       The narrow profit margins in the refinery business motivate us to extend the useful life of our assets without significant investments. One of the refinery's key assets is its electrolytic cells; the current refinery has 1,776 active cells, most of which were installed 20 to 30 years ago nearing the end of their design lifespan. To address declining cell performance, we sought to improve cell tightness, eliminate current leakage, enhance current efficiency, and prevent structural deterioration. The concept of using monolithic cell liners emerged as a solution to these challenges. These liners offer a practical method for replacing or repairing damaged cells while maintaining production capacity. They are designed to operate at high temperatures and withstand corrosive electrolytic acid solutions. Additional benefits include improved thermal insulation, potentially leading to energy savings. This paper details the design, manufacturing, installation, and performance of these monolithic cell liners at the Chuquicamata Refinery, focusing on initial production phases and progression from late 2024 to early 2025. This work was carried out in collaboration with the North American company Sunwest, which specializes in manufacturing this type of monolithic coating.

   11. Copper Electrowinning: 2025 Global Survey of Tankhouse Operating Practice and Performance

       Michael S. Moats, Andreas Filzwieser, Rodrigo Abel

       Abstract

       Operating data were collected from many copper electrorefineries around the globe. This survey builds upon previous work presented at every Copper meeting since 1987. Anode composition, electrolyte chemistry, electrolysis parameters, tankhouse design, and cathode quality are analyzed and discussed. This paper honors Professor William Davenport for his many contributions to this survey series and the dissemination of copper processing knowledge.

   12. Digitalized State-of-the-Art Short-Circuit Detection (ESCD) for Increased Tankhouse Efficiency

       Matthias Lindthaler, Andreas Filzwieser

       Abstract

       In copper refining tankhouses, short circuits can decrease current efficiency by up to 10%, creating operational inefficiencies that require timely and accurate intervention. Traditional methods, such as manual inspections and static thermal imaging, often fall short in addressing these challenges due to limited coverage and high personnel demands. This study presents an innovative short-circuit detection solution using thermal cameras equipped with rotational heads that monitor the cell surfaces from oblique angles, providing comprehensive, real-time coverage of the entire tankhouse. By implementing cameras with rotational capabilities, this system significantly reduces the number of cameras needed, compared to crane-mounted or drone-based monitoring solutions, while achieving superior area coverage. The cameras’ oblique perspective captures extensive sections of the tankhouse, allowing for a detailed temperature profile of anodes and cathodes across the hall. A key technical challenge was converting these angled captures into top-down thermal images that could be accurately mapped to cell locations. Additionally, individual camera feeds are integrated into a unified thermal map, providing operators with a complete overview in real time. This approach offers substantial advantages, including immediate short-circuit detection, optimized current efficiency, and enhanced stability in electrolyte quality. The automated detection system continuously updates and transmits data to a central server, facilitating rapid analysis and targeted interventions without interrupting operations. By reducing the number of required cameras and minimizing manual oversight, this technology supports more efficient resource allocation and improved tankhouse stability. Overall, the integration of rotational thermal imaging represents a cost-effective, high-precision alternative for monitoring large refining facilities, enabling sustainable improvements in energy consumption and refining efficiency through real-time, hall-wide short-circuit detection.

   13. Alternative Technology for Processing Scrap in Refineries

       Juan Patricio Ibáñez, Yuri Lepiman, Marco Cifuentes, Jonkion Font, Hugo Cancino

       Abstract

       A novel reactive electro-dialysis (RED) cell was employed at the laboratory scale to process industrial scrap, producing a high-purity acidic electrolyte with a controlled copper and sulfuric acid content while minimizing impurities such as As, Sb, and Bi. This electrolyte can be directly reused in electro-refining cells or utilized for the production of CuSO₄·5H₂O, copper foil, copper nanoparticles or 5N cathodes. The anodic reaction involves the oxidation of scrap, releasing cupric ions into the electrolyte, while the cathodic reaction reduces protons from an acidic solution, generating hydrogen gas. The resulting electrolyte contained approximately 180 g/L of H₂SO₄, 45 g/L of Cu, less than 75 mg/L of As, and less than 10 mg/L of Sb and Bi. Additionally, the process generated around 300 m³ of hydrogen gas per ton of dissolved scrap, with the potential to produce an equivalent volume of high-purity water.

   14. Refining Methodology for Cu SXEW Mist Suppressant Validation

       Julius Heidlas, Zachary Ruetz, Brenda Chanez

       Abstract

       Acid mist generation continues to be an issue faced by the mining industry, stemming from O₂ generated by electrolysis during copper electrowinning. It has previously been controlled by use of reagents that are being phased out, opening the door to new chemistries. BASF has developed a comprehensive approach to validating mist suppressing reagents at laboratory scale. This test regime addresses mist reduction, plating, solvent extraction (SX) compatibility, and stability. Standard methods have been developed that allow rapid vetting of potential candidates, with confidence and reproducibility. Additionally, attention has been given to detection and quantification of potential mist reagents in Cu SX plant streams.

   15. High Current Density Operation at Toyo Tank House

       K. Kurimoto, R. Aoki, K. Takenaka, T. Fuke, S. Endo, T. Kudo

       Abstract

       Toyo Smelter & Refinery, Sumitomo Metal Mining Co., Ltd. produces 450,000 tons of high grade copper per year in three tank houses. Conventional starting sheet technology has been used at Toyo tank house #1 and Niihama tank house. The Niihama tank house commenced operations in 1919. The current density at the Niihama tank house and the Toyo tank house #1 has reached 320 A/m² with approximately 100 years of operational experience and technological advancements. To achieve high current efficiency under condition of 320 A/m² operation, both tank houses have undertaken measures to optimize the adjustment of the cathode assembly machine and the anode pressing machine in order to improve the verticality of cathodes and anodes and to maintain uniform distances between cathodes and anodes. Additionally, the concentration of the electrolyte was meticulously controlled to prevent anode passivation, and the adjustment of the processing raw materials to regulate the impurity concentration in the electrolyte was also improved to maintain stable high current density operations. As a result, a current efficiency close to 98% was achieved at a current density of 320 A/m². This report outlines the improvements that have been implemented to date.

   16. Recent Advances in ISAKIDD Cathode Design and Cathode Stripping Machines

       Andrew D. Spencer, Addin Pranowo, Per O. Eriksson, Michael McNally, Ådne Prestø Lie

       Abstract

       Since the late 1970s, permanent stainless steel cathode technology has been employed in copper refining, beginning with Copper Refineries Limited in Townsville, Australia. The initial ISA Process featured copper-plated stainless steel hanger bars and split sheet cathodes. Later, the Kidd Creek operation in Canada introduced a solid copper hanger bar and enveloped (taco) cathode design known as the Kidd Process. Today, Glencore Technology has merged both technologies as ISAKIDD. This paper discusses advancements in cathode design and cathode stripping machine (CSM) development within the ISAKIDD technology. Although the cathode product remains either split or enveloped, hanger bar design has evolved based on operational experience and plant requirements, with two main designs currently in use. A newer hanger bar design, the ISAKIDD hanger bar, incorporates a copper core sheathed in stainless steel for enhanced corrosion protection from acid mist. Cathode blade materials have shifted from the initially dominant 316L grade austenitic stainless steel to duplex grade stainless steel, which favoured for its higher tensile strength and improved chloride corrosion resistance, making it suitable for harsher environments. To facilitate plate identification and tracking, refineries have the option to fit RFID tags to cathode plates, enabling more detailed data collection and analysis. CSM technology has seen ongoing improvements in automation, with newer machines employing robotics. However, older technologies like pivot arm semi-automatic machines remain popular in smaller operations due to cost-effectiveness and simplicity. The most recent ISAKIDD technology delivery to Nikkelverk's electrowinning plant includes a state-of-the-art robotic CSM, RFID-tagged cathode plates, ISAKIDD hanger bars, and duplex stainless-steel blades.

   17. Effect of Additives in the Electrorefinery Start-Up of PT. Freeport Indonesia

       Arif Aji, Henni Pudas, Fikri Irawan, Petteri Linja

       Abstract

       Starting up one of the world’s biggest copper refineries, PT. Freeport Indonesia was using a typical electrolyte containing [Cu] of 50 gpl, Free Acid of 170 gpl, [As] of 3 gpl and [Cl] of 0.05 gpl. While anodes quality has a range of Cu and O₂ of 99.4–99.7% and 500–600 ppm, respectively. Due to the limited number of anodes, the only option was to start one group out of 16 groups, using only 10% of the design capacity. This gap affected the performance of equipment, such as pumps and heaters. Another limiting factor was unavailability of the solution purification section at that stage. To mitigate soluble impurities and copper from the anodes, circulating five additional cell groups was conducted. This provides challenges in additives dosing, and some iterations of additives dosing was conducted during the start-up. Despite the unusual set-up and typical start-up challenges, such as unwanted stops, the copper refinery start-up was successful, producing LME grade A from the first cathode. Result of 2nd cycle shows significant improvement in quality improved production by minimizing dendrite growth and increasing current efficiency and further, the result of the 3rd cycle is shown to produce best cathode among these three cycles.

   18. Tankhouse Material Handling at Heding Copper 620,000 tpa Copper Electrorefinery

       Martti Larinkari, Tianlu Guo, Lauri Palmu, Jian Yue

       Abstract

       Heding Copper (Zhejiang Jiangtong Fuye Heding Copper Co., Ltd.) operates modern copper electrorefinery in Fuyang province, China. The copper electrorefinery started operation in 2014, which was followed by two expansions in 2017 and 2022. Today the design capacity of the electrorefinery is 620.000 tpa. Starting point of the design has been that electrode harvesting must be completed in one working shift. This set high requirements for tankhouse material handling system in terms of performance and reliability. Inner lug anode design is applied to ensure safe and fast simultaneous lifting of electrodes. Tankhouse material handling is based modern high-capacity machines, which provides continuous throughput with minimum intervention by the operators. Highly integrated solution enables uninterrupted and balanced material flow in the tankhouse, where more than 10 machines operate simultaneously. Experiences from TACO (“envelope”) cathodes have shown that high stripping capacity reaching over 600 cathodes/h can be maintained. This paper describes the basic design, working methods and tankhouse material handling technology enabling high production efficiency, which have been demonstrated over 10 years in Heding Copper.

   19. Implementing Automated Inspection Systems in Copper Tankhouses

       Quade Howald

       Abstract

       As global demand for copper rises, the refining industry faces pressure to improve efficiency, quality, and profitability. Traditional manual inspections in copper tankhouses are labor-intensive and error-prone. This work presents an AI-driven vision system with machine learning for real-time defect detection, quality control, and process optimization in copper tankhouses. Implemented at an operational facility, the system uses high-resolution cameras and deep learning to detect defects, showing early improvements in accuracy and efficiency. This case study aligns with Copper 2025 themes of “Process Control & Optimization” and “Electrowinning & Electrorefining,” showcasing AI’s role in advancing copper refining.

   20. Approach and Case Study for Optimum Copper Tankhouse Design

       Ole Wagner

       Abstract

       Global refined copper demand continues to rise, mainly due to increased electrification, such as electric vehicles. Electrolysis is the primary method for refining copper today and in the foreseeable future. This places significant importance on achieving optimum designs for brownfield and greenfield tankhouse projects. While the overall concepts and designs of tankhouses have remained largely consistent for nearly a century, technological advances have driven significant incremental improvements and optimizations, setting modern plants apart from those of the past. These advancements include automation, robotics, improved process equipment efficiency, monitoring systems, and information management. This paper outlines an approach for optimal tankhouse design aimed at owners and designers seeking to understand modern design practices and tailor solutions for their specific projects. It highlights optimization opportunities for both brownfield and greenfield projects using new technologies. While “optimal” varies by project, the universal framework offers a flexible methodology for diverse scenarios. This paper references a recent European refinery rebuild project where the client needed a basic engineering package for a new 230 kt/a copper tankhouse. By closely collaborating with the client, the design team proposed operational optimizations, resulting in a best-in-class tankhouse design. The project improved upon the previous facility and included flexibility for expansion to 350 kt/a of cathode production.

   21. Modernization of Ilo Copper Refinery with Permanent Cathode Technology to Produce the Heaviest Cathodes in the World

       M. Munguia, F. Begazo, H. Choque

       Abstract

       After 50 years of continuous operation, the SPCC Ilo Copper Refinery is carrying out its modernization project with the aim of renewing its major equipment, which has frequent stops that entail production losses. The project consists of implementing permanent cathode technology to replace the current copper starting sheets technology. Project implementation does not consider an increase in production; however, it has been conceptualized so that it is aligned with future expansions. The project has been divided into 5 stages, which include the development of metallurgical tests at industrial level to prove the technical feasibility of the new process. The present work describes the results achieved in the tests, in which cathodes up to 190 kg have been produced maintaining high current efficiency (> 98.0%), with an excellent metallurgical rejection rate due to physical appearance (<1%). The conception of the project and the design of the process have been carried out using the know-how of the technical staff of the Ilo Refinery, who also designed and manufactured a semi-automatic machine for stripping heavy cathodes in the tests stage. The cathodes are being commercialized as a new product (SPCC-ILO-PE), which has the same chemical quality as currently recognized SPCC-ILO copper cathodes.

   22. Performance Testing of a New Non-fluorocarbon Acid Mist Suppressant for Copper Electrowinning

       Tim Doubleday, William Szolga, Tyler McCallum, Jose Carlos Durazo, Justin Jensen, Luis Moya

       Abstract

       Sulfuric acid mist is an undesired by-product of the copper electrowinning process. The use of physical controls such as cell hoods or the addition of chemical mist suppressants are typically employed to effectively mitigate the health hazards associated with acid mist. However, a recent focus for the copper solvent extraction and electrowinning (SX-EW) industry has been to test new mist suppressants due to the phase out of the previously used fluorocarbon based mist suppressants. A suitable alternative must demonstrate effectiveness in mist suppression at economic concentrations, compatibility with the solvent extraction (SX) circuit and organic phase, along with compatibility in electrowinning (EW) without impacting plating performance or cathode quality. In this paper, a new non-fluorocarbon mist suppressant, ACORGA^® EW98, is presented, which has demonstrated acid mist suppression along with SX and EW compatibility. Performance testing will be reviewed from initial development studies and pilot test work to evaluations at an industrial-scale test.

   23. Enhancing Efficiency, Grid Stability, and Grid Code Compliance: The Critical Role of Rectifiers and Harmonic Filter Systems in Modern Electrowinning and Electrorefining Plants

       Scott Nelson, Rodrigo Dunner, Alex Steciuk

       Abstract

       The reason for this tech talk is to discuss how DC Power supply and harmonics filter can affect the efficiency of your product, in cost of AC electrical power per ton of product you get out. Also, AC grid stability, which can affect other departments in the plant and even the neighbors. And lastly, we will discuss AC grid compliance, and how different systems can greatly cause an effect on it. To understand how this all affects the cost of equipment, the electric bill, and compliance and penalties, we will cover the following key areas. The beginning of IEEE 519 AC grid compliance, rectifier typographies, the restrictions, and limitations from the standards. The advancements in power technology, and the advancements in Harmonic filtering and mitigation. The cost impacts related to harmonics, on not only the equipment that produces the product, but all the other equipment in the plant that is receiving the line harmonics from the equipment. Also, the substation transformer costs and potential damage. Plant-wide power harmonics filters are an advantage for long-term protection for all electrical equipment. It is also important to have the proper power factor and harmonic monitoring equipment. This is necessary for those preventing higher electric bills, increasing strain the power grid. This prevents running equipment above their ratings, advanced aging of equipment, or even damages power equipment. The key is that with the proper design and monitoring of a DC power system and harmonic filter, to meet the latest standard of IEEE519 and to not incur an electric penalty.

   24. Acid Mist Suppressant: A Non-fluoro Environmentally Friendly Surfactant to Reduce Acid Mist Formation in Copper Electrowinning

       Kwame Boateng Amoafo, Christopher Andrew Hight, Francisco Garcia, Nobuzwe Makhotla, Syed Zaka Ahmed, Jose P. Ruiz

       Abstract

       Acid mist formation is a significant safety concern during electrowinning operations and there is significant interest in finding new solutions to this problem due to the discontinuation of an industry standard fluorine-based additive. This study discloses that a non-fluorine-based additive can be utilized as an environmentally friendly acid mist suppressant, low-foaming with no detrimental effect on the cathode quality and solvent extraction. The effect of these additives was laboratory assessed in comparison to the historically used fluorine-based additive and an existing natural extract-based surfactant. Initial results have shown that these additives not only effectively suppress the acid mist formation in electrowinning process but also improve cathode quality with no adverse effects on solvent extraction observed during laboratory trials.

   25. Development of New Austenitic Stainless Steel Cathode Grade for More Efficient Copper Electroplating

       Mikko Palosaari

       Abstract

       Austenitic stainless steel Supra 316L/1.4404 has been utilized for decades as permanent cathode plates in the last stages of pure copper production. Outokumpu Europe has a long experience in supplying cathode specific steel for this use. The development of more efficient copper electroplating material was initiated in order to increase the lifetime and reduce the cost fluctuation of permanent cathode plate steels. Permanent cathode plates are immersed in a corrosive environment, i.e. in sulphuric acid solution where it is expected that the steel does not corrode or dissolve during the operation. The solution may consist of corrosive elements like chlorides, which together with elevated temperatures increase the material requirements. The corrosion resistance of industry standard Supra 316L/1.404 is achieved by a combination of ~17% chromium and 2.0% molybdenum alloying. Additionally, nickel content must be minimum of 10% in order to achieve austenitic non-magnetic microstructure at the room temperature. Recently developed austenitic stainless steel grade Supra 316plus/1.4420 is designed in such manner that the corrosion resistance is achieved by increased chromium (20.3%) and nitrogen (0.20%) levels. Additionally, the nickel content was reduced down to 8.6% and molybdenum down to 0.7% while retaining fully austenitic microstructure. This paper shows the development of cathode specific Supra 316plus/1.4420 product. Copper electroplating and adhesion performance have been compared to the typical Supra 316L stainless steel in a laboratory environment by test plating and by measuring the separation force. Surface micrographs showcase the importance of surface microtopography on the copper nucleation, growth and adhesion on top of stainless steel. Mechanical properties are also compared and advantages in the copper stripping operation are reviewed.

   26. State-of-The-Art Tankhouse Technology—Factoria Copper Verde, a New Project in Spain

       Filzwieser Iris, Filzwieser Andreas, José A. Mira Herrera

       Abstract

       In Córdoba, Spain, CUNEXT is developing a cutting-edge copper refinery that prioritizes sustainability and efficient resource use. At the core of the facility is advanced tilting furnace technology, enabling the production of anodes from recycled copper scrap. This circular approach significantly reduces reliance on primary mining, conserving natural resources and mitigating environmental impacts. High-purity copper cathodes are produced through an innovative electrolysis process, ensuring superior quality and efficiency. The refinery's initial production capacity stands at 100,000 tonnes of cathodes per year, with plans to expand to 130,000 tonnes in a second phase. METTOP GmbH, based in Leoben, Austria, was selected for the engineering, procurement, and project management (EPPM), ensuring the integration of state-of-the-art technologies. A commitment to energy efficiency defines the plant’s operations, including the use of green electricity and the elimination of fossil fuels, which substantially reduces energy consumption compared to traditional methods. E-mobility solutions manage material transport within the facility, cutting dependence on gas-powered vehicles. These innovations enable one of the industry’s lowest CO₂ footprints while delivering cost savings and enhanced resource efficiency.

   27. Electrorefining High-Ni, -Sb and -Sn Anodes from a Primary Copper Smelter

       Agustin Morales Aragon, Michael S. Moats, Daniel Sánchez-Rodas, Guillermo Rios

       Abstract

       Incorporating impurities, particularly from the recycling of e-scrap, may significantly impact the electrorefining process of the anodes from a copper smelter. In this study, commercial anodes were doped with Ni, Sn and Sb to achieve concentrations of 2500–6500 g/t, 300–900 g/t and 450–950 g/t, respectively. Electron microscopy with microprobe analysis revealed that the doped anodes contained NiO, Kupferglimmer and SnO_2, which were not present in the original commercial anodes. Ni, the main impurity, primarily accumulated within the Cu grains, while Sn and Sb tended to form oxidized inclusions. The distribution of Ni in Cu grains was ca. 20% lower in the anodes doped at higher Ni concentrations due to the formation of nickel-bearing inclusions, such as Kupferglimmer and NiO. The doped anodes showed lower quantities of Cu₂O inclusions than the commercial anodes due to the preferential formation of oxides with these added impurities. X-ray diffraction of the slimes collected after electrorefining the doped anodes in a small laboratory cell using commercial electrolyte revealed that new phases generated in the casting process deported to the slimes. These findings highlight potential challenges for Cu electrorefining in a circular economy, as increased Ni, Sb and Sn content will impact the composition of slimes and electrolyte.

   28. Segmentation Effect of 4-Contact Insulators on Reducing Short Circuits and Energy Consumption in Copper Refineries

       Robert Dufresne, Hamid Arabzadeh

       Abstract

       Short circuits are a known challenge in electrorefining, often resulting in production downtime, noticeable increase in energy consumption per tonne of plating, safety concerns, and costly maintenance. To address this, an innovative solution known as segmented 4-contact insulators has been developed to decrease the incidence of short circuits while also significantly lowering energy usage and achieving notable cost savings. This research presents an advanced version of capping board insulators called “4-contact Ecolectrik,” which is engineered to uphold the efficiency of cellhouse operations even when faced with a bad contact or short circuit. The 4-contact design features four independent electrical contacts, providing redundant electrical pathways and enhancing fault tolerance. The design objectives are confirmed through electric circuit simulations across various short-circuit and bad contact scenarios. The analysis reveals that the segmented design of these insulators localizes the effects of short circuits, and the use of bypass secondary contact bars that supply the electrodes from the insulated end in the event of a bad contact results in more uniform and reliable distribution of cell voltage and current. Additionally, an assessment of electric current distribution within a cellhouse indicates that employing this type of insulator could lead to energy consumption reductions of up to 23% per tonne of plating. The adoption of these insulators also improves the overall safety of the refining process by reducing the risk of electrical hazards associated with short circuits. With a proven track record in demanding refinery environments, these insulators offer a reliable and cost-effective solution for short circuit protection in copper refineries. Moreover, by enabling better control of the refining process, these insulators contribute to higher quality metal production, minimized waste, and enhanced sustainability, particularly in areas where electricity is sourced from fossil fuel power plants utilizing coal or oil and result in a reduced carbon footprint.