Cross-Cutting Symposia

Inhaltsverzeichnis

1. Responsible Mining/Processing

   1. Frontmatter

   2. Mining and Social Responsibility: Assessing the Role of Community Investments

      Emilio Castillo, Constanza Araya-Ibarra

      Abstract

      Company-community relationships are increasingly seen as vital tools for promoting local development. These relationships often take the form of provisions for income distribution, local investments, environmental protection, and socio-economic development. Historically perceived as transactional, the substantial financial commitments highlight their potential for significant community impact. However, there is a pressing need for robust evaluation systems to measure the socio-economic outcomes of these investments. Data from 42 mining companies reveals inconsistencies in how Community and Social Investment (CSI) are defined and reported. From 2018 to 2022, CSI-to-EBITDA ratio varied between 0.1 and 4.7%. While CSI-to-Revenue ratio varied between 0.01% and 1.97%. Significant events, like the Brumadinho dam disaster and the COVID-19 pandemic, influenced these investments. However, detailed reporting on CSI projects remains limited, with inconsistencies in the types of projects funded and their impacts. This underscores the need for improved transparency and evaluation to ensure these investments effectively contribute to local development.

   3. Enhancing Recovery of Critical Metals Indium, Germanium, and Antimony from Metallurgical Processes Through Thermodynamic Modeling

      Elmira Moosavi-Khoonsari, Saleh Rasouli-Jouryabi, Abbas Ahmadi Siahboumi, Jesus Alejandro Arias-Hernandez, Manel Houria

      Abstract

      Advancing toward a sustainable society relies on intensive use of critical metals such as indium, germanium, and antimony. This requires improving their recovery rates in metal production, finding value in waste materials and creating new recycling methods. However, there are gaps in our understanding of critical metal behavior in metallurgical processes. A promising approach to understanding the distribution behavior of these target metals is integrating systematic thermodynamic modeling with key experiments. This work aims to develop a comprehensive thermodynamic database for oxide systems, via adding critical element oxides like GeO₂, In₂O₃, and Sb₂O₃ to major slag components such as PbO, ZnO, CaO, SiO₂, and FeO. Our methodology involves creating physics-based machine learning models to estimate the thermodynamic properties (\(\Delta H_{298.15K}^{0} , S_{298.15K}^{0} , C_{P}\)) of critical metal-containing oxides, which are often scarce in current literature. This model will support thermodynamic modeling of phase equilibria and diagrams based on the CALPHAD method, validated through experiments. The resulting oxide database can be linked with existing metal and gas databases, allowing for predictive modeling of current processes and exploration of new recovery methods for critical metals from waste streams, including by-products from copper, lead, and zinc production, as well as electronic waste. This integration enables reasonable calculations of how critical metals distribute across different phases (metal, slag, and gas), helping to identify optimal conditions, like composition, temperature, and oxygen levels, within the complex parameter space of multi-component systems. This work summarizes the challenges, advancements, and findings achieved so far.

   4. Critical Mineral Co-production Through Full-Value Copper Mining

      Dawn Wellman, Saskia Duyvesteyn, Cory Smith, Carlos Eyzaguirre, Kaci Jenkins, Lukas Fahle

      Abstract

      Innovation and a new look at traditional mine resources are opening advancements necessary to secure the critical mineral domestic supply chain. What was once viewed as waste or by-product streams are now becoming key national resources. Through partnerships and technological advancements, Rio Tinto is turning the copper value chain into a gateway to critical minerals and unlocking new socially responsible and economically viable gateways to critical minerals such as tellurium, bismuth, indium, germanium, gallium, and others. This presentation gives an overview of work in the development of these value streams, from technological innovation to implementation.

   5. An Investigation of Rare Earth Element Occurrence at the Kennecott Copper Operation and Implications for Recovery

      Megan Guenther, Shannon Ulrich, Jeffrey Gillow, Tassos Grammatikopoulos, Dawn Wellman, Saskia Duyvesteyn

      Abstract

      The seventeen elements that comprise Rare Earth Elements (REEs) are considered critical minerals by the United States Geological Survey (USGS). REEs have unique spectroscopic and magnetic properties that enable them to play an important role in industrial and advanced material sciences applications. However, the United States is nearly 100% reliant on imports for REEs, lacking sufficient domestic resources and processing capabilities. To ensure resilience across U.S. energy and defense needs, the United States must secure reliable and sustainable domestic supplies of REEs. To address this need, Rio Tinto has established a project to determine the ability and extent to which its North American Copper assets could provide REEs for the national supply chain. This project has focused primarily on Rio Tinto Kennecott, an integrated copper mining operation located in Utah. This project aims to characterize the enrichment of REEs and occurrence of REE-bearing minerals within the orebody and various processing streams at Kennecott and explore possible routes for their recovery. Here, we present characterization work completed thus far, including an evaluation of REE enrichment in the rock types present at the Kennecott mine, as well as results from a detailed mineralogical study of REE-enriched ore from Kennecott using bulk geochemistry, electron microscopy, and automated mineralogy. We also discuss the current outlook and options for recovery of REE-minerals given the occurrence of REEs within the Kennecott orebody and processing streams.

   6. Sustainable Foundations: Enhancing Project Viability Through Sustainability Readiness

      John Michael Simmons

      Abstract

      Sustainability and Environmental, Social, and Governance (ESG) are interconnected but serve different purposes. While ESG is a data-driven tool used to measure an organization’s operational performance in the key areas of Environment, Social and Governance using relevant benchmarks and metrics, Sustainability is a principle or philosophy focused on maintaining long-term business viability and responsible operating practices. ESG relies on operational data to measure performance, while Sustainability provides the strategic framework that shapes and informs those data-driven outcomes. Sustainability connects seamlessly into virtually all functions of a business and its projects, driving forward-looking, responsible decision-making and long-term value creation. Potential project failure is often significantly influenced by sustainability factors within the ESG pillars, as failing to identify these critical criteria through failed sustainability efforts can lead to regulatory challenges, community opposition, and irreparable reputational damage.

   7. CLEVR Process™—Parametric and Technology Transfer Interlaboratory Study

      Joey Isabelle, Elisabeth Drouin, Brent Dereck Johnson, Jean-Philippe Mai

      Abstract

      This study was done in collaboration with a world’s leading gold mining company to evaluate the technical applicability of DST’s CLEVR Process™ as an alternative to cyanidation for gold extraction at one of its deposit projects located in South America, a region known for its opposition with the use of cyanides due to environmental risks associated with the process. The CLEVR Process™ is a hydrometallurgical process operating in a closed-loop circuit and using in-situ chlorine and bromine generation from sodium hypochlorite and halides salts in acidic media for the purpose of gold and platinoids extraction. Its fast reaction kinetics, high efficiency, relatively low waste production and health, safety and environment (HSE) risk makes it a favorable option for gold miners when compared to the traditional cyanidation. An extensive series of tests were performed at the laboratory scale on 4 typical low-bearing sulzides materials ranging from 1.7 to 6 g/t of gold supplied by the miner (2 feed ores and 2 gravimetric tails). A parametric study was performed to better define the impact of the following conditions on the process efficiency: hypochlorite concentration, operating pH, contact time, particle size, solids percentage and material. Gold extraction efficiency under optimized conditions reached above 97% for the oxide material tested without pre-treatment ([NaOCl] = 4%wt, [NaCl] = 70 g/L, [NaBr] = 10 g/L, pH < 1, ORP > 950 mV, contact time = 2 h, P90 = 80 µm, %solids = 45%, room temperature). The solid residue resulting from the CLEVR Process™ is one of the few waste streams generated in the process. Consequently, its characterization is of obvious interest and presented in this paper. The residue was found to be non-hazardous, based on the Toxicity Characteristic Leaching Procedure (TCLP—EPA1311). An interlaboratory study based on ASTM E2935-15 Standard Practice for Conducting Equivalence Testing in Laboratory Applications was also conducted in the scope of the study with the gold mining company. Relevant documents (SOPs, control sheets, visual support, etc.) were shared between both laboratories and 10 representative sub-samples issued from the same material (5 for each lab.) were prepared and used for the technology transfer. Analytical and operational results were compared for 7 tests (3 performed by DST and 4 performed by the gold mining company).

   8. Microwave-Assisted Pretreatment for Enhanced Rare Earth Element Recovery from Vietnamese Bastnaesite Ore

      Wonhong Song, Jihye Kim

      Abstract

      Rare earth elements (REEs) are essential for modern technologies, yet their extraction from bastnaesite remains challenging due to its refractory fluorocarbonate structure. Conventional processing methods, such as alkali roasting and acid baking, require high energy input and generate significant chemical waste. This study investigates microwave-assisted pretreatment with alkali additives as an alternative to conventional methods, aiming to improve REE leachability while reducing energy consumption. Bastnaesite concentrate was pretreated with NaOH, Na₂CO₃, and K₂CO₃, under microwave irradiation, followed by hydrochloric acid leaching. Among the tested additives, NaOH proves most effective, achieving nearly complete REE recovery due to its lower decomposition temperature. The process was optimized using the design of experiment methodology, revealing that HCl concentration, solid-to-liquid ratio, and NaOH-to-bastnaesite ratio significantly influence leaching efficiency. Under optimal conditions, 98.4% REE recovery was successfully achieved. This research demonstrates the potential of microwave-assisted pretreatment in enhancing REE extraction efficiency while minimizing environmental impact.

2. Strategies for Decarbonization

   1. Frontmatter

   2. Production of HREE Carbonate from the Lofdal HREE Flotation Concentrate Using a Simplified Hydrometallurgical Flowsheet

      Niels Verbaan, Eileen Ross L. Espiritu, Jing Liu, Tassos Grammatikopoulos, Barbara Mulcahy, Rainer Ellmies

      Abstract

      The Lofdal rare earth element (REE) project is one of the few rare earth deposits in the world that contains mostly heavy rare earth elements (~ 75% HREO distribution). The mineralogy of the Lofdal project is complex, with xenotime as the primary rare earth hosting mineral, and silicates, calcite, and iron-oxide as the main gangue minerals. A 2023 flotation pilot plant produced a ~ 93 kg concentrate sample, which was used for acid bake scale-up tests and simplification of the liquor treatment process to recover a mixed heavy REE carbonate from the concentrate. This paper provides an update on the laboratory testing programs conducted to develop a significantly simplified process.

   3. Electric Fluidized Beds for Mineral Processing

      Imtiaz Ahmed, Marc Duchesne, Yewen Tan

      Abstract

      Fluidized bed technology is favorable for mineral processing due to its ability to enhance heat transfer, improve reaction kinetics, and ensure uniform mixing. Applications such as calcination, roasting, and drying benefit from the consistent temperature control and efficiency that fluidized beds provide. By replacing traditional fossil-fuel-based heating with electric heating systems, electrified fluidized beds can reduce carbon emissions while maintaining high operational efficiency. This study identifies potential applications for electric fluidized bed technology in mineral processing, identifies associated challenges and opportunities, and proposes various solutions through a combination of process analysis, bench-scale experiments, and modeling.

   4. Aluminothermic and Magnesiothermic Reduction of Rare Earth Compounds for Production of Alloys: Thermodynamic Evaluations

      Ahmad Rizky Rhamdani, M. Akbar Rhamdhani, Geoffrey Brooks, Mark I. Pownceby, Yudi Nugraha Thaha, Trevor B. Abbott, John Grandfield, Chris Hartley

      Abstract

      Rare earth (RE) elements can improve the properties of aluminum and magnesium alloys when added as an alloying agent. A simple way to produce Al–RE or Mg–RE alloys is by adding RE metals to Al alloy or Mg alloy. However, the high price of RE metals means that an alternative route to produce the alloy is needed. An alternative way to make RE–Al/Mg alloys is by directly reducing RE compounds with Al or Mg. In this study, a systematic thermodynamic evaluation of the ability of aluminum and magnesium to reduce different rare earth compounds was carried out. RE oxide, fluoride, and chloride systems were analyzed, with emphasis on RE chloride. The results showed that only Sc was expected to be reduced by Al in all assessed systems, while La and Ce could only be reduced by Al in the oxide form and none of the Y compounds assessed were reduced by Al. Magnesium was expected to be able to reduce La and Ce in the oxide form, while not in the fluoride and chloride forms.

   5. Utilization of Accelerated CO2 Mineralization in Hydrometallurgy: A Review

      Mojtaba Adelalipour, Fei Wang, Houshang Alamdari

      Abstract

      Integrating accelerated CO₂ mineralization with hydrometallurgical processes offers a promising strategy to reduce industrial carbon emissions while improving the sustainability of metal extraction. Mineral carbonation converts CO₂ into stable carbonates using divalent metals like magnesium (Mg), calcium (Ca), and iron (Fe). Although naturally slow, the reaction rate improves significantly under high-temperature, high-pressure conditions and with fine particle sizes—though industrial-scale implementation remains challenging. In hydrometallurgy, these same metals are often treated as impurities during extraction. Their reactivity with CO₂ creates an opportunity for sequestration, turning a waste stream into a carbon sink. Moreover, mineral carbonation can unlock low-grade critical metals like nickel and cobalt embedded in the rock, enabling their recovery as valuable by-products. By aligning CO₂ capture with metal extraction, this integrated approach improves economic viability, supports a circular resource model, and offers a scalable solution to decarbonize the metal industry. This review provides an in-depth analysis of this strategy, addressing current technological challenges and outlining necessary future research.

   6. Thermodynamic Analysis of the Selective Solid-State Reduction of Electric Arc Furnace Dust by Methane

      O. Marzoughi, C. A. Pickles, L. Tafaghodi

      Abstract

      The growing emphasis on sustainable steel production has made the management and recycling of electric arc furnace (EAF) dust increasingly critical. EAF dust, a hazardous byproduct of steelmaking, contains valuable metals such as zinc and lead but is difficult to efficiently process. Current treatment methods are often energy-intensive and environmentally unfriendly. This study investigates a more sustainable alternative by analyzing the solid-state reduction of EAF dust using methane. A thermodynamic model, developed with HSC Chemistry^® 7.1, was used to predict the equilibrium products of this reduction process. The modeling results identified the optimal conditions for maximizing metal recovery while minimizing environmental impact.

   7. Lithium Metal Production via Room-Temperature Electrolysis

      Michael Dziekan, Matthew Earlam, John Hryn

      Abstract

      Worldwide production of lithium metal is currently estimated at 2000 tons per year, while 2050 demand is estimated to be more than 5 million tons per year. The escalating global demand for lithium metal, primarily driven by its critical role in clean energy technologies, necessitates significant advancements in lithium production methods. Lithium metal production is currently hindered by high energy consumption and chlorine gas generation as the industrial method for producing lithium metal involves high-temperature electrolysis of molten lithium chloride, which produces both molten lithium metal and chlorine gas. Argonne National Laboratory has developed an innovative lithium electrowinning process that produces lithium metal at room temperature. This technology significantly reduces environmental impact by eliminating the generation of chlorine gas and instead produces oxygen as a byproduct. The process leverages treated domestic spodumene or processed lithium chloride brines as flexible lithium sources, catering to fluctuating market conditions.

   8. Challenges in Modelling Lithium Systems Using Independent Supply and Demand Models

      Brent McNeil

      Abstract

      Lithium is essential for advanced energy technologies, particularly in rechargeable batteries, necessitating accurate modelling of its future supply to address potential shortages and sustainability challenges. Current models often treat supply and demand independently, leading to unrealistic projections and uncertainty. This study identifies key challenges in lithium supply modelling, including inconsistencies in resource classification systems like JORC, NI 43-101, and UNFC, and the limitations of bottom-up analyses due to geopolitical risks and data transparency issues. Additionally, recycling uncertainties and shifts in battery technology and electric vehicle adoption further complicate demand forecasting. Scenario-based modelling and economic analysis are proposed to better capture the dynamic interactions between supply and demand. Recognizing the unpredictable nature of geological and societal factors is crucial for developing resilient models to ensure a stable lithium supply for global decarbonization efforts.

3. Backmatter