12th International Copper Conference

Inhaltsverzeichnis

1. Frontmatter

2. Auxiliary Processes/Acid Plants

   1. Frontmatter

   2. Metallurgical Sulfuric Acid Plant Quench Challenges

      Dan Falcioni, Maysam Moham, Jeff Chenier, Douglas Louie

      Abstract

      Sulfuric acid plants play a critical role in metallurgical operations by treating SO₂-bearing off-gas, with their efficiency closely tied to overall plant performance. Gas quenching, which cools gases from 300–500 °C to 50–60 °C, presents significant design and maintenance challenges due to thermal stresses and chemical exposure. Specialized materials such as potassium silicate and furan resin mortars, along with acid-resistant bricks, are used to protect quench systems but remain susceptible to wear and corrosion. Maintenance intervals typically range from 2 to 6 years. This study compares traditional elbow quench designs with newer vertical designs, highlighting that both require regular maintenance. While elbow designs typically require complete replacement or major overhauls every 4 to 10 years, vertical designs offer significantly longer lifespans—potentially eliminating the need for full replacement. Modular systems facilitate faster repairs, minimizing downtime. Proper material selection and periodic maintenance can enhance system longevity. The study provides valuable insights into optimizing maintenance strategies and material choices to improve the reliability of quench towers in metallurgical operations.

   3. Evolution of Rio Tinto Kennecott Acid Plant SO2 Gas Leak Detection

      Alan D. Castañon Sandoval, Keough Austin

      Abstract

      This comprehensive overview explores the dynamic evolution of sulfur dioxide (SO₂) gas leak detection methods within sulfuric acid plants, with a focus on historical and modern techniques applied to Rio Tinto Kennecott’s (RTK) acid plant and the smelter gas train. The historical progression from simple chemical indicators to sophisticated electronic detectors, including autonomous optical gas imaging (OGI), and AI-powered infrared imaging technology is examined in the context of proactive care and maintenance, environmental stewardship, and good neighbor practices, utilizing emerging technology to minimize industrial impacts on local communities, and a need to stay well informed of the available resources industry can use to characterize impacts. The outline summarizes key detection methods, the incorporation of artificial intelligence (AI), algorithms and machine learning methods, and the chemical reactions involved in historical methods. Regulatory standards, such as those set by OSHA for SO₂ exposure limits, are discussed alongside the potential health repercussions at different exposure levels. Additionally, the mechanisms by which environmental regulation can mandate fugitive SO₂ limits are explored. The conclusion underscores the significance of the changes made at the RTK acid plant to excel in environmental and safety standards. Adherence to local air quality standards further emphasizes the necessity for advanced leak detection methods. This paper serves as an insight into the historical changes, current practices, and the regulatory landscape of SO₂ gas leak detection at RTK acid plant.

   4. Management of SO2 from Diluted Streams in the Met-Mex Peñoles Lead Smelter

      Josué C. Cháidez, Víctor Luevano, Carlos I. Fernández, Isaías Almaguer, Jeremy D. Gillis

      Abstract

      Met-Mex Peñoles processes lead sulfide concentrates in its lead smelter using the sinter-blast furnace process. The rich sulfur dioxide gas (6% SO₂) generated in the sintering process is used to produce sulfuric acid, meanwhile the more dilute SO₂ streams (<1.5% SO₂) are sent to an ammonium sulfate plant to absorb the SO₂ with a water-based ammonium solution creating a rich ammonium bisulfite/sulfite by means of a counterflow packed scrubber with five sections. This first step produces ammonium bisulfite at 35% concentration in water. The plant was designed to then produce an ammonium sulfate solution at 42% concentration through acidification and the regenerated SO₂ gas was used to produce liquid sulfur dioxide or gas which could be sent to the acid plants, and the liquid ammonium sulfate was sent to Peñoles’ fertilizer plant, Fertirey for crystallization. Fertilizer production has not been economically attractive for several years, so the company has looked for alternatives, and is now focused on selling the 35% ammonium bisulfite solution, which is a widely used reagent in the mining industry. It is used in cyanide detoxification and floatation circuits for Pb-Cu separation. The present paper describes the ammonium bisulfite process and the results of its use at industrial level for cyanide detoxification.

   5. Sulfuric Acid Production in the Copper Industry—A Review with Future Insights

      Rene Dijkstra, Matthew King, Herbert Lee

      Abstract

      Recent sulfuric acid manufacturing technology developments have led to the design of acid plants with significantly lower emissions, enhanced energy recovery, and improved reliability—all of which provide more sustainable solutions for the copper industry as it supports the global energy transition. This paper provides a fundamental review of sulfuric acid manufacturing techniques along with a detailed technical comparison of acid plants designed to treat copper smelter off-gas and those designed to produce acid from sulfur at copper leach facilities. Process and mechanical limitations inherent to each type of acid plant design are identified. New pathways and technologies are described that overcome these limitations leading to acid plants that are safer to operate, more energy efficient, with lower capital and operating costs.

   6. Review of Ballestra Plant Project in DRC: Sulfuric Acid and Liquid SO2 CO-production

      Alessio Libardo

      Abstract

      This paper outlines the engineering, phased commissioning, and operationalization of a high-capacity sulfuric acid production unit, integrated with the copper and cobalt extraction operations of the KCC mine in the Democratic Republic of Congo. Designed for a production capacity of 2200 metric tons per day, the project achieved its ambitious timeline, completing the design to start up in less than 3 years, thanks to a modular approach by Ballestra that utilized pre-designed and pre-tested plant sections.

   7. Gain and Retain Talent in Sulfuric Acid Plants with Online Asynchronous Training Methods

      Carolina Hernandez, Gerard Prins, Dirk van der Werff

      Abstract

      Effective training is essential for safe, efficient, and environmentally responsible smelter and sulfuric acid plant operations. However, the industry faces challenges such as workforce retirement, shifting preferences, and resistance to new technologies. Academia.Holtec addresses these issues with flexible, multilingual online courses covering equipment design, process control, troubleshooting, and safety. Based on 25 years of experience, the courses equip both new and experienced operators with practical skills, improving efficiency, reducing errors, and ensuring compliance.

   8. WSA, the Resilient Solution to Fluctuating Lean SO2 Gases

      Samuel Scherman Johansson

      Abstract

      The copper industry faces increasing pressure to reduce SO₂ emissions. While treating strong SO₂ gases is standard, handling lean and fluctuating SO₂ off-gases is a future challenge. These gases, which can have both low SO₂ concentrations and be highly fluctuating, present both operational challenges and opportunities. This paper explores the sources of these gases in copper smelters and specific obstacles that may arise when these are to be handled. The paper focuses on efficient methods for dealing with sulfurous off-gases and examines innovative solutions like the Wet Gas Sulfuric Acid (WSA) process to enhance sulfur abatement, energy efficiency, and regulatory compliance.

   9. Improving Plant Performance and Operational Readiness by the Application of Numerical Process Simulation

      Torsten Weber

      Abstract

      The interest in the application of numerical process simulation has constantly been growing over the last decade, also in sulfuric acid and wet gas cleaning plants of metallurgical production complexes. While the approval process to invest into a simulation model is often lengthy, the advantages of having such models are obvious. A virtual copy of the plant or separate units thereof allows a close look onto the plant performance and how it deviates from the optimum operational windows. Analysis can be broken down to single equipment or control loops to allow for detailed investigation and optimization. In this regard, not only are standard operating conditions in the focus, but also transitional or upset plant conditions. As a result, the more economic use of raw materials and utilities, as well as an increased lifetime of the equipment is achieved. Continuous performance monitoring provides valuable data about the condition of catalysts and equipment, allowing for realization of enhanced predictive maintenance concepts. Applying simulation models for operator training purposes and troubleshooting completes the list of benefits.

   10. Smelter Acid Plant—Replacement Hot Gas Exchanger Case Study

       Neal Londry, Werner Vorster

       Abstract

       Sulfuric acid plants attached to copper smelters often experience high SO₂ gas concentrations entering the first converter pass, resulting in very high outlet gas temperatures. The hot gas exchanger downstream of the first pass is therefore a critical piece of equipment and may be routinely exposed to gas temperatures in excess of 650 °C (1,200 °F). The combined effects of hot gas corrosion and the potential for excessive thermal stress on the tubes make for one of the most severe service cases seen in sulfuric acid plants. NORAM has been engaged to design and supply a replacement hot gas exchanger for Rio Tinto Kennecott’s large copper smelter acid plant in Utah, the design of which is a useful case study in general strategies to mitigate the deleterious effects of high temperatures on gas-to-gas heat exchangers. In addition to general solutions, the design process also highlights the usefulness of more advanced techniques, such as computational fluid dynamics, in identifying and remedying issues unique to a particular heat exchanger, or other acid plant equipment.

3. Economics and Markets

   1. Frontmatter

   2. Mineral Exploration and the Discovery of New Deposits: A Quantitative Analysis of Gold and Copper Discoveries

      Emilio Castillo, Cintia Roa

      Abstract

      Mineral discoveries are a critical outcome of exploration activities, shaping the future availability of non-renewable resources. While prior research emphasizes the importance of geological potential and institutional quality in exploration decisions, empirical analyses of the determinants of exploration success remain limited. This study examines the drivers of mineral discoveries using data on gold and copper deposits alongside national-level exploration expenditures. Results reveal that exploration budgets are the primary determinant of success, while institutional quality has minimal direct impact when budgets are accounted for. Notably, findings suggest risk-seeking behavior among exploration firms, as rising marginal discovery costs exceed commodity prices. These insights underscore the need for better strategies and coordination in exploration stages to ensure the long-term availability of minerals.

   3. Value Proposition of Copper Mining Projects: Analysis of Its Fulfillment, Deviations, and Causes in the 2015–2022 Period

      Luis Lagos, Emilio Castillo, Felipe Sánchez

      Abstract

      The copper industry, driven by the energy transition scenario, is projected to grow from 1.2 Mt in 2020 to 3.5 Mt in 2030 and 5.4 Mt in 2040. This growth requires increased production by expanding existing operations or new mining projects. Given these market demands, this study focuses on greenfield projects and their value propositions—specifically, investment amounts, timelines, and project scope. The methodological framework employed assesses the fulfillment of the value proposition in terms of investment amount, production start dates, and scope for the global portfolio of copper mining projects from 2015 to 2022. The approach consists of five steps: data collection, portfolio characterization, project selection, descriptive statistical analysis, and clustering using the K-means algorithm. By clustering, it is possible to evaluate the level of similarity between projects and identify key factors influencing the fulfillment of their value propositions. This research enhances the understanding of key factors affecting the value proposition of mining projects, emphasizing the critical role of socio-environmental variables. These factors require further exploration through the compilation of regional best practices. Finally, the study underscores the importance of robust strategic analysis during the pre-investment stages, particularly in business case evaluations, where the identified factors can guide discussions and improve decision-making processes. It will also highlight critical factors affecting the fulfillment of their value propositions.

   4. Regional Market Dynamics: A Marginal Pricing Approach

      Isabel Diersen, Ruiyi Wang, Alison Wang, Richard Roth, Elizabeth Moore, Elsa Olivetti

      Abstract

      The shift to renewable energy technologies depends heavily on critical minerals, such as copper. Experts predict that copper demand will soon exceed the current supply, potentially leading to a significant supply–demand gap in the coming decades. To address this gap, governments around the world have enacted policies to promote the exploration and development of new mines. Additionally, some governments have introduced or proposed policies, such as subsidies and tariffs, to further incentivize and expand the production of domestic copper. These policies may lead to changes in the distribution of the copper supply chain and differences in regional prices of copper. This study builds upon an existing model of critical minerals supply evolution that integrates price feedback and mine operation decisions by expanding the model’s capacity to analyze short-run supply risks. A “marginal pricing” approach is developed for metals supply modeling where mine-level opening, closing, and production decisions are made based on the “margin” between the current commodity price and the mine’s operating and capital costs. “Marginal pricing” can be applied to analyze various short-run scenarios, particularly public policies aimed at incentivizing domestic sourcing of critical materials.