Cross-Cutting Symposia

Table of Contents

1. Recycling and the Circular Economy

   1. Frontmatter

   2. Impurities in Lithium Streams: How They Will Impact Your Economics

      Kinnor Chattopadhyay, Alan Nelson

      Abstract

      Lithium is primarily extracted from hard rock (spodumene ore) using hydrometallurgy or from salar brines using solar evaporation techniques. The main desirable products are lithium hydroxide and lithium carbonate salts. These salts are available in various grades, ranging from crude to superior. The main difference between these grades is the minimum lithium content and the maximum tolerable impurities. Impurities influence production processes, cathode quality and performance, and, most importantly, safety. Most lithium battery faults originate from the presence of impurities. This, coupled with production processes and safety aspects, puts pressure on material purity, with a focus on trace elements’ characteristics and their content. The total impurity is usually defined as the sum of impurities and contaminants. Today, there is extensive research and development activity on alternative lithium extraction processes, including the recycling of lithium-ion batteries, lithium extraction from clays, and direct lithium extraction from various types of brines (salar, geothermal, petro, and produced water). As these new sources of lithium are explored, it is crucial to understand the impurity profiles in the lithium streams, as most companies aim to produce/sell battery-grade lithium salts. Certain players may not achieve this due to a lack of technical know-how and the inability to invest in additional purification capital expenditure (capex). However, they may consider selling an intermediate product to an off-taker, which may be an established lithium company or even a centralized lithium refinery. Impurities will play a significant role in determining payables received from refineries (off-takers), as lithium streams with high impurities will receive very low payables, thereby affecting the economics of the intermediate producers.

   3. The Effect of Temperature on Solubility and Insolubility of Compounds During Monazite Sulfuric Acid Baking: A Mini-Review

      Mahta Fakhraei Rad, Nazanin Bahaloo-Horeh, Farzaneh Sadri

      Abstract

      Rare earth elements (REEs) are critical in numerous high-tech applications as the world moves toward sustainable and clean technologies. Various burgeoning sectors, including water treatment, medical science, and electrical engineering, increasingly rely on REE resources, with ~ 95% of global reserves associated with the minerals monazite, bastnaesite, and xenotime. A critical step in processing these REE-bearing minerals is chemically cracking their structures to release REEs for extraction. Acid baking is one of the most widely utilized pretreatment techniques for breaking down mineral structures and producing intermediate compounds that can be effectively leached in subsequent steps. Efficient mineral decomposition varies across REE minerals due to their complex mineralogy, which often includes impurities like iron oxide-hydroxides (e.g., hematite, goethite, magnetite) and radioactive elements such as thorium and uranium, complicating the selective extraction of REEs. Adjusting processing conditions to convert REEs into soluble compounds while maintaining impurities in an insoluble state is crucial for minimizing environmental, technical, and economic challenges in downstream processing. This paper aims to address impurity management in acid baking pretreatment techniques by examining the effect of process temperature on the selective extraction of REEs. By investigating the chemistry and extraction behavior of both REEs and impurities during acid baking, this work highlights opportunities for optimizing conditions, with particular emphasis on minimizing environmental impact, enhancing economic feasibility, and improving resource efficiency to advance REE recovery practices.

   4. The Use of Magnesium Thiosulfate Solution to Leach Gold from Disposed Cell Phones

      T. L. Akpomejero, M. D. Shittu, D. A. Isadare, B. Aremo, K. E. Oluwabunmi

      Abstract

      This study investigated the leaching of gold from discarded cell phone printed circuit boards (PCBs) using magnesium thiosulfate solution as a safer alternative to cyanide. The objectives included analyzing and pre-concentrating the pulverized PCBs, optimizing leaching efficiency, and electrowinning the extracted gold. The PCBs were pulverized and analyzed using energy dispersive spectroscopy (SEM/EDX) to confirm the gold content. Magnetic separation was used to remove ferrous components, followed by treatment with trioxonitrate (V) and hydrogen tetraoxosulfate (VI) acids to eliminate base metals like copper and zinc. The residue was then leached with the thiosulfate solution with various concentrations of copper (II) sulfate and ammonia added to enhance gold dissolution. The leachate was used for electrowinning, and the gold content was analyzed with SEM/EDX. The result showed maximum gold dissolution of 0.70 ppm. EDX analysis confirmed the presence of gold in the electrowinning deposit. The study concludes that gold can be extracted from electronic waste using this method, offering a viable alternative for precious metal recovery and improving electronic waste management.

   5. An Eco-Friendly Approach for Gallium Recovery from Aqueous Solutions Using Immobilized Siderophores

      Nazanin Bahaloo-Horeh, Lan Van Leeuwen, Farzaneh Sadri

      Abstract

      Critical metals like gallium play essential roles in various high-tech applications, from electronics to renewable energy systems. However, limited natural availability and complex extraction processes create significant challenges. Conventional recycling methods for gallium often suffer from low selectivity, high costs, and environmental drawbacks, underscoring the need for more sustainable recovery techniques. This study presents a novel method for gallium recovery from waste streams and leaching solutions using the microbial metabolite siderophore Desferrioxamine B (DFOB), immobilized in sodium alginate through a Ca²⁺ cross-linking method. By leveraging the unique metal-binding affinity of siderophores combined with the stability and ease of handling provided by alginate hydrogels, this approach aims to enhance metal recovery efficiency while minimizing environmental impacts. The immobilization conditions of DFOB in alginate were optimized by adjusting parameters such as alginate, siderophore, and Ca²⁺ concentrations, as well as immobilization time, which increased the loading efficiency from below 20% to over 80%. Under optimal conditions, the immobilized DFOB-alginate beads achieved over 98% recovery of gallium from 100 ppm Ga solutions within 24 h. Additionally, selectivity tests using synthetic solutions containing nickel, cobalt, and aluminum showed that the siderophore-alginate beads exhibited a high selectivity for gallium, particularly over the divalent ions of nickel and cobalt. This enhanced selectivity is attributed to the specific chelation structure of DFOB, where hydroxamate functional groups play a crucial role in gallium binding. Compared to alternative adsorbents, the immobilized siderophores in alginate hydrogels demonstrated superior selectivity and higher adsorption capacity for gallium, offering a sustainable and low-impact solution for its recovery. The findings of this study pave the way for utilizing siderophores in eco-friendly technologies for recovering various critical metals from leaching solutions and waste streams.

   6. Green Chemistry and Zero Liquid Discharge Process for Complete Recovery of Lithium, Cobalt, Manganese, and Nickel from Lithium-Ion Battery Cathodes

      Alexandru Sonoc, Lan Van Leeuwen, Farzaneh Sadri

      Abstract

      A green chemistry hydrometallurgical process has been developed to recycle cathode material from lithium-ion batteries and produce sodium-free Li₂CO₃ as well as mixed Co, Ni, Mn sulfates without generating either liquid or solid waste. The only reagents are formic acid and sulfuric acid. The key step in the process is leaching cathode materials (e.g., LiNi_1/3Co_1/3Mn_1/3O₂) with formic acid, which is accompanied by in situ crystallization of sparingly soluble Co, Mn, and Ni formate salts. In the present work, the kinetics of the leaching reaction are examined.

   7. Advancing Tailings Reprocessing: Pilot-Scale Sulphide Recovery and Mechanochemical Leaching for Sustainable Resource Recovery

      Maziar E. Sauber, Antonio Di Feo, Yevhen Kravtsov, Jophat Engwayu, Arik J. A. Collins, Charlotte Gibson

      Abstract

      This study advances the sustainable reprocessing of Cantung historical mine tailings through a pilot-scale plant focussed on sulphide recovery, aiming to mitigate acid mine drainage and promote environmentally responsible mining. Building on previous bench-scale work, the pilot plant successfully scaled up the separation of sulphide minerals, reducing the environmental impact of the tailings. Parallel bench-scale experiments explored mechanochemical leaching using caustic soda, enhancing the extraction of tungsten-bearing minerals. The pilot plant demonstrated successful sulphide recovery, while bench-scale leaching tests showed improved metal extraction, offering a combined approach for sustainable tailings reprocessing and resource recovery.

   8. Selective Recovery of Gallium and Indium from E-Waste via Sulfidation and Distillation

      Ethan Benderly-Kremen, Antoine Allanore

      Abstract

      The demand of gallium and indium have increased dramatically in the past decades due to the unique electronic properties of their chemical compounds, which form the backbone of all modern opto-electronic devices. Gallium, in the compounds gallium arsenide and nitride (GaAs, GaN), is the emitter material of light emitting diodes (LEDs); and indium, in the form of indium tin oxide (ITO), is a transparent conductor vital for liquid crystal displays (LCDs) to operate. Although earth abundant, these metals have no concentrated deposits and are recovered as byproducts from within the solid solutions of bauxite (Ga, primary aluminum) and sphalerite (In, primary zinc). One way to lessen the demand on this highly inelastic supply is to increase recovery via recycling of electronic waste (e-waste). However, the chemical environments in which these metals are located in e-waste, as a nitride and ternary oxide, are incompatible with re-introduction to the primary extraction path. Herein we introduce sulfidation followed by vacuum distillation as a pyrometallurgical pathway capable of selectively recovering and concentrating both gallium and indium out of their e-waste compounds. The results of this study have been used to inform the design of a batch reactor capable of recovering 50 g/h (≈ 0.5 tonne/year) of target metal, the results of which are published elsewhere (Benderly-Kremen et al. in JOM 77(11), 2025).

   9. Removal and Recovery of Metallic Impurities from Lithium-Ion Battery Black Mass: A Kinetically Optimized Multi-Modal Approach

      Jeff Green, Saurabh Prakash Pethe, M. Parans Paranthaman, Fulya Dogan, Kae Fink

      Abstract

      Achieving true circularity for the critical materials utilized in lithium-ion batteries requires advancements in the state-of-the-art for battery recycling. Fine battery scrap (“black mass”) contains residual metallic contaminants (Cu, Al, Fe, etc.) as well as non-metallic impurities (e.g., plastics) that reduce recycled material performance and may ultimately induce catastrophic cell failure. Successful direct recycling of black mass relies on the effective removal and recovery of these metallic contaminants under conditions that do not adversely impact the cathode material. In the present work, we demonstrate a multi-modal purification approach based on tailored alkaline chemistry to selectively leach metallic contaminants from a matrix of black mass. Process conditions have been rationally tuned at the pre-pilot scale to minimize processing time while maximizing the purity of the resulting output product. We utilize a diverse suite of purification strategies—including oxidation, chelation, magnetic separation, flotation, and membrane extraction—in a single batch system to selectively target, remove, and recover impurities from battery black mass. We have developed a circular offtake strategy for the reclaimed Al impurity product, and have also identified further treatment optima for the resulting cathode material to promote optimized surface conditions for subsequent direct recycling treatment. Herein, we present on the development of this method from idealized bench-scale optimization experiments to scale-up and demonstration in an industrially relevant reactor system. We report on the efficacy of purification utilizing a series of real-world battery black mass samples that have been variably pre-processed. We also demonstrate successful integration this method with upstream and downstream direct recycling processes. Finally, we address the reclamation of metallic impurities as valuable side-products from our purification method. Our optimized multi-modal approach represents a promising strategy to purify battery black mass fines under conditions that both retain the engineered value of the cathode product and enable recovery/reuse of the metallic contaminants, thereby maximizing overall value to the critical materials supply chain.

   10. Environmentally Benign Extraction of Lithium from Underclay Coal Waste

       Patrick Abban Sarpong, Thandazile Moyo-Mahlangu

       Abstract

       The global energy transition has increased the demand for critical minerals, including lithium (Li), prompting interest in recovering them from underclay coal waste. This study aims to determine the most efficient mild-lixiviant when combined with mechanical activation at bench scale to maximize lithium recovery from underclay. Water-leaching experiments (at 75 °C) on mechanically activated underclay yielded low recoveries of up to 24%, constrained by Li encapsulation within insoluble mineral matrices. Organic acid leaching tests using citric, oxalic, and DL-malic acids (0.5 and 1.0 M) at 75 °C achieved nearly 100% Li extraction after 4 h. DL-malic and oxalic acids were effective, outperforming citric acid, a result attributed to their lower acid dissociation constants (pKa) and enhanced metal complexation ability. This research demonstrates the potential of mechanical activation combined with organic acids as a sustainable and environmentally friendly alternative to conventional mineral-acid-based processes for recovering Li from coal waste underclay.

   11. Development of Hydrogen Plasma Reactor for Smelting and Reduction of Oxides

       Bima Satritama, Chris Cooper, M. Akbar Rhamdhani, Andrew Ang, Dian Fellicia, Reiza Mukhlis, Duy Quang Pham, Chris Berndt, Geoff Brooks, John Pye, Alireza Rahbari

       Abstract

       Electrification and hydrogen play a vital role in the decarbonization of heavy industries, including in minerals and metallurgical processing. Considering this, many researchers are re-investigating hydrogen plasma for a low-carbon technology for application in minerals and metallurgical processing. Hydrogen plasma (monoatomic H and ionic hydrogen H⁺) offers a thermodynamic advantage as it has a very high reductive potential and capacity for reducing stable compounds/oxides such as CaO, MgO, Al₂O₃ and rare earth oxides. This paper discusses the development of a unique hydrogen plasma reactor for reduction, smelting and refining of metals/materials at Swinburne University of Technology, called SwinH₂Plas. The reactor consists of a 35 kWhydrogen plasma torch, a specially designed 3D-printed copper shroud, a vertical reactor tube and powder collector. The plasma torch allows a continuous feed of powders; hence the reactor can be operated as a continuous process. The initial test of the reactor was carried out using iron oxides (naturally occurring magnetite and hematite) and partially reduced iron oxide as source materials. The results revealed significant iron formation with only 2% to 10% H₂ concentration in the gas mixture. Globular iron and slag and partially reduced particles with size 20–50 µm were obtained at the powder collector. Further optimization of operating conditions is being carried out for stable operation with high metallization and different oxides feed.

   12. Selective Recovery of Copper from Waste Printed Circuit Boards by Ammoniacal Solvoleaching

       Kurniawan Kurniawan, Jae-chun Lee, Sookyung Kim

       Abstract

       This study introduces an innovative method for the selective extraction of copper from waste printed circuit boards (WPCBs) using a single-stage leaching and solvent extraction (SX) process, employing the organic extractant, 2-hydroxy-5-nonylacetophenone oxime (LIX 84-I), with addition of a small amount of NH₄OH (ammoniacal solvoleaching). Copper can be selectively recovered by the proposed ammoniacal solvoleaching; following the optimization of leaching parameters, over 68% of Cu from WPCBs was recovered. Copper can then be efficiently stripped from the loaded organic solution using H₂SO₄. Notably, LIX 84-I maintains its extraction efficiency through multiple leaching-stripping cycles. Ammoniacal solvoleaching offers a practical and sustainable method for the simple and selective extraction of Cu from WPCBs.

   13. Hydrometallurgical Recovery of Lithium from Wastewater Generated During Direct Battery Recycling Processes

       Kurniawan Kurniawan, Jessica Durham-Macholz

       Abstract

       With the rising demand for lithium-ion batteries, efficient recycling methods are crucial to reduce environmental impact and minimize primary resource consumption. This study explores the recovery of valuable metals from materials obtained after battery direct recycling. Direct battery recycling focuses on selective impurity removal (e.g., copper, aluminum, and graphite) to produce a partially refined cathode material that requires minimal further processing. In contrast, black mass—generated from crude crushing of batteries—contains higher impurity levels and undergoes a series of hydro- and pyro-metallurgical processes to isolate key battery metals. To maximize the recovery of lithium, nickel, cobalt, and manganese, this research optimizes leaching and solvent extraction methods. The recovered materials are then purified to industrial standards, enabling their incorporation into the synthesis of new cathode materials. This study aims to advance a circular economy for critical materials by improving the efficiency and sustainability of battery recycling.

   14. Extraction of Platinum Group Metals from Spent Catalysts Using Iron Chloride Vapor Pretreatment

       Yu-ki Taninouchi, Toru H. Okabe, Kohei Sunagawa, Hiroaki Nakano

       Abstract

       The recovery of platinum group metals (PGMs) from spent catalysts is crucial for maintaining a sustainable PGM supply. However, achieving this in an efficient and environmentally friendly manner is challenging due to the chemically stable of PGMs, which makes them resistant to dissolution in acids, and their low concentration on scrap materials. In this paper, we introduce a novel approach for PGM recovery that involves a treatment of spent catalysts with FeCl₂ vapor at relatively low temperatures (< 1200 K). During this treatment, alloying of PGMs proceeds via the disproportionation of FeCl₂ vapor, resulting in the formation of ferromagnetic Fe-PGM alloys. Experimental confirmation of this phenomenon was achieved by subjecting Pt, Pd, and Rh wires to FeCl₂ vapor treatment. In fundamental tests using samples simulating automobile catalysts, PGMs were successfully concentrated through magnetic separation following vapor treatment. Moreover, leaching tests using aqua regia on pulverized automobile catalysts demonstrated enhanced PGM extraction, particularly for Rh, after vapor treatment. Thus, a process involving FeCl₂ vapor treatment, magnetic separation, and acid leaching is a viable and useful method for recovering PGMs from spent catalysts.

   15. Cost and Environmental Impact Assessment of Lithium-Ion Battery Recycling: Sustainable Solutions for a Circular Economy

       Nighat A. Chowdhury, Sabine M. Gallagher, Qiang Dai, Jeffrey S. Spangenberger

       Abstract

       The surge in electric vehicle adoption will inevitably lead to rapid growth of end-of-life vehicles and spent lithium-ion batteries (LIBs). Recycling these LIBs is imperative for environmental sustainability and unlocking their economic potential, while ensuring a consistent supply of materials for future battery production. Developing recycling technologies that are both cost-effective and environmentally sustainable is essential for addressing the challenges of managing battery manufacturing scrap and end-of-life lithium-ion batteries. Recycling efforts to recover lithium salts from spent LIBs are still in their early stages, with significant technical and operational obstacles to be overcome. Currently, various methods, such as pyrometallurgical, hydrometallurgical, and direct recycling processes, are being employed and actively advanced by researchers to improve their performance and feasibility. This study investigates the industrial-scale hydrometallurgical and pyrometallurgical processes for recycling lithium from end-of-life LIBs to provide a comprehensive analysis of their cost and environmental impacts. This study aims at establishing a baseline for emerging recycling technologies for lithium by studying the commercial recycling processes and examining their different unit processes with a process-level understanding. By assessing emerging recycling methods in EverBatt, an excel-based cost and environmental impact analysis model for battery recycling process and supply chain, this study identifies critical drivers and barriers to process scale-up, such as economic hurdles, material recovery rates and operational scalability, alongside environmental hotspots like greenhouse gas emissions and energy use.

   16. Gold Extraction from Printed Circuit Boards Using a Ferricyanide-Based Compound

       Joseph Pearlman, Jaeheon Lee

       Abstract

       A ferrocyanide-based compound called E-series is proposed as an environmentally friendly and more selective alternative to cyanide for leaching gold (Au) from e-waste, specifically, from printed circuit boards. E-series uses a combination of ferrocyanide and thiourea to accomplish these requirements. Experiments show that E-series can leach Au faster and copper slower than cyanide, and that increasing the temperature increases both the selectivity and the leaching kinetics. The effect of changing the concentration of E-series was also investigated, and it was found that lower concentrations have a higher selectivity while having slower leaching kinetics. Overall, E-series is found to be a much safer and more effective lixiviant for leaching Au than cyanide.