Industrial Li-ion battery recycling typically relies on pyro- or hydrometallurgical routes that recover metals efficiently but require complex pretreatment, heavy chemical use, and destroy the morphology of cathode materials, limiting direct reuse. This work explores semi-continuous wet high-intensity magnetic separation (WHIMS) as a reagent-free method for concentrating Ni-Co-Mn (NMC111) cathode material from -63  µm black mass using only crushing and screening as pretreatment. Two steel matrices were tested. With the fine matrix at 0.9  T, 95% NMC recovery was achieved at 85 wt% grade. The coarse matrix at 1.1  T yielded 80% recovery at 90 wt% grade, preferentially recovering morphologically intact particles. WHIMS performance was influenced by particle liberation and matrix geometry. These results demonstrate that WHIMS can recover NMC while preserving its original morphology, a key step for direct recycling. Future work should focus on optimizing key parameters and assessing the upscaling from laboratory to pilot scale, including alternative WHIMS configurations to enhance selectivity, and evaluating the integration of WHIMS with other processes for multi-product recovery.

As lithium-ion battery (LIB) demand increases, there is growing interest in their recycling to reduce the environmental impact of mining. The safe handling of end-of-life batteries during transportation, storage and mechanical treatment requires development of environmentally sustainable and industrially scalable discharging processes. In this context, electrochemical discharge shows promise due to its simplicity, robustness, and potentially low cost. NaCl solution has been extensively studied as a promising discharge medium because of its availability and reportedly fast discharge potential. However, the use of NaCl aqueous electrolyte solutions has resulted in casing corrosion, which is associated with inefficient discharge and losses of critical raw materials. To overcome these issues, the present study offers for the first time an in-depth exploration of the potential mechanisms responsible for LIB corrosion in NaCl solutions. It is found that corrosion is a consequence of multiple parallel reactions driven by the presence of dissolved oxygen produced during electrochemical water splitting. As the corrosion pathways are identified, a novel approach is proposed to prevent it, namely, the use of Zn-salts as corrosion inhibitors. The experimental results suggest that Zn2+ ions aid in corrosion prevention in three main ways: (i) by forming non-soluble Zn(OH)2 with OH- ions produced on the metal surfaces; (ii) by forming mixed Fe-Zn oxide in corrosion pits; and (iii) by consuming electrons from the battery during discharge and forming a sacrificial anode of metallic Zn. The present work thus proposes an economical and reliable approach to discharge LIBs efficiently using aqueous electrolyte media.

Driven by sustainability goals and raw material scarcity issues, recycling of spent lithium-ion batteries is becoming imperative. Pyrolysis is commonly employed for the removal of polymers to improve the liberation of active materials, yet its impact during the thermal degradation remains unexplored. Thus, the present study investigates the effect of pyrolysis time and temperature on the liberation and composition of "black mass (BM)." Thermal decomposition of various size fractions of an industrial BM was studied using thermogravimetric analysis and bench-scale pyrolysis, while characterization before and after pyrolysis was performed using X-ray diffraction and scanning electron microscopy. Furthermore, analysis of gaseous byproducts during pyrolysis using Fourier transform infrared offered insights on the decomposition byproducts and their environmental impact. It is hereby demonstrated that, while pyrolysis results in the partial degradation of polymeric binders, this is not the result of pure thermal degradation. Indeed, graphite, polymers, and Al reduce cathode active materials into metallic species via in situ carbothermic or aluminothermic reduction, producing Al2O3, COx, and alkanes. The experimental results are rationalized into a reaction mechanism for pyrolysis of black mass, revealing that pretreatment via pyrolysis can compromise the preservation of battery active material and needs to be carefully considered during direct recycling routes.

The increasing demand for lithium-ion batteries (LIBs) to support the global efforts in reducing carbon emissions have also made necessary the search for more efficient battery recycling technologies to prevent the depletion of raw materials. Pyrolysis, flotation and leaching are potential recycling unit processes that have recently drawn the attention as pretreatment, separation and dissolution methods in processes aimed at the recovery of materials from spent batteries. However, a study which systematically investigates the advantages and limitations resulting from the integration of these operations is still missing. In this work, an integrated experimental approach was applied to evaluate the recycling efficiency of pyrolysis, flotation and leaching together with their various combinations for the treatment of an industrially produced black mass. The results show that pyrolysis decreased the presence of cathode material in the graphite concentrate, increasing graphite purity from 60 to 80 %, although with a negative impact on graphite recovery from 60 to 50 %. Furthermore, the use of pyrolysis increased the leaching yield of metals from 40 to above 80 %. Additionally, the leaching yields of Ni and Co were further increased by nearly 5 % when flotation was applied, even without pyrolysis. With the combination of pyrolysis and flotation prior to leaching, an increased dissolution yield of metals from black mass was found for all the metals, particularly Ni (from 13.7 g/L to 19.8 g/L). The sole exception to this trend was Li, likely due to its dissolution in the flotation water. A rationalized explanation of this behavior is presented, supported by the characterization of the feed and product materials obtained under each different scenario. This work thus demonstrates that properly designed recycling stages can have a tangible impact in the process efficiency.

Among the major challenges facing the mineral processing industry is the simultaneous need to increase productivity while reducing environmental impact. This study explores the potential of polymer- surfactant (PS) mixture composed of short-chain alcohols combined with hydroxypropyl methyl cellulose (HPMC) as a new environmentally friendly frother produced from sustainable sources. Ethanol, pentanol, and octanol were evaluated as surfactant fraction due to their availability and relatively low cost, alongside the polyglycol based commercial frother (Dowfroth 200) as a benchmark. The result demonstrates that longer-chain alcohols are more effective at preventing bubble coalescence, longer-chain alcohol achieving unimodal distributions at lower concentrations. Interestingly, HPMC exhibited unique behavior due to its macromolecular structure, forming a stable yet slow-diffusing layer around bubbles, resulting in bimodal distributions even at higher concentrations. Mixtures of HPMC and alcohols, particularly pentanol and octanol, show synergistic effects that enhance the initial stabilization of the air-liquid interface, facilitating unimodal distributions at relatively low concentrations. These findings offer valuable insights for optimizing frother formulations to improve flotation efficiency.

Froth flotation remains the most widely used method for concentrating metallic ores. However, the consistently increasing demands for raw materials and the stricter environmental regulations require strategies that increase productivity while simultaneously reducing the environmental impact of mining operations. With the aim of addressing these issues, the present study explores a new froth stabilization reagent consisting of amphiphilic cellulose and alkyl alcohols. Measurements of bubble size, foam height and foam medium lifetime were performed using hydroxypropyl methyl cellulose (HPMC) in combination with ethanol, pentanol or octanol. The results show a cooperative interaction between alcohols and HPMC, with the former playing a dominant role in the control of bubble size and the latter promoting the stability of the foam. When used for the flotation of chalcopyrite model ore, the PS-mixture was capable to produce a final recovery of ca. 99% while providing fast flotation kinetics, even under low collector dosage (i.e., 5 g/t ore). In comparison, a benchmark polyglycol commercial frother (i.e., DowFroth 200) reported a significant decline in flotation kinetics as collector dosage was reduced. This work shows that alkyl alcohols and cellulose mixtures are promising sustainable reagents in the concentration of minerals.

With the growing demand for raw materials to enable the ongoing electrification transition, robust battery recycling technologies will also become necessary to reduce reliance on primary resources and improve sustainability. To boost the recovery of secondary materials, we combined HSC-Sim (R) recycling process simulations with data science to analyze the flow of Li-ion battery components through the processing stages. Key operating parameters of the process were varied to assess their impact on material recovery and grade of graphite anode (Gr) and nickel-manganese-cobalt cathode (NMC). The resulting data distributions allowed us to establish if the process design was capable of producing desired recovery outcomes, and under which set of conditions optimal performance could be obtained. Materials flow analysis was utilized to guide decision-making and iteratively redesign the recycling process towards better outcomes. In the final stage, multi-objective optimization was deployed to achieve a balance between maximal NMC mass recovery of 66.3% at 95.7% grade and Gr mass recovery of 88.7% with 99.8% grade. This scalable, data-driven framework could replace intuition-led recycling process trials with rational process design to optimize complex device recycling, accelerating the transition towards more sustainable and effective material recycling.

As a result of ongoing research on direct recycling of battery active materials, it was observed that the chemical environment in flotation operations can be manipulated to produce highly stable froths. Such unexpected behavior opened the possibility to characterize this type of metastable structures using imaging techniques such as x-ray computed tomography. In this article, a first successful three-dimensional reconstruction of a live mineral froth is reported, unveiling its structural intricacies with micron-scale detail. Using this novel approach, it was possible to observe the distribution of solid species in the froth and the corresponding bubble geometries. Furthermore, the results challenge prevailing notions about the flotation mechanisms of cathode particles, emphasizing the need for more selective reagents in the flotation of end-of-life batteries.

The HELIOS European project, funded by the H2020 Programme, aims to develop lighter, modular hybrid Li-ion battery packs for EVs that combine same-size modules with high-power and high-energy cells to meet customer demands for fast charging and long-range capabilities. Nevertheless, it is important to consider the potential environmental impacts associated with the disposal of such hybrid batteries. This includes the consumption of a wider range of raw materials, the release of hazardous substances, and the emission of greenhouse gases. To address these concerns, the HELIOS project also focuses on improving the sustainability of the battery pack by creating designs for easy reuse in second-life applications and by developing recycling strategies at the End-of-Life (EoL) of the battery pack. The project has progressed in three key research areas: 1) Designing the battery pack to incorporate possible second-life scenarios using a modular configuration and enhanced dismantling techniques. 2) Froth flotation experiments were carried out to study whether graphite could be recovered in a reusable form and to create data for future LCA calculations. 3) Parallel to the froth flotation experiments, LCA methodology supported by the ISO 14040 series was used to create a baseline to evaluate the environmental impacts of the hydrometallurgical recycling of the NMC811-graphite cells. This baseline could be used later to assess the impact of graphite recovery by froth flotation, as the current LCA baseline excludes the recovery of anode materials (graphite and LTO).

The introduction of alternative anode chemistries into the market, such as lithium titanium oxide (LTO), will likely generate challenges in lithium-ion battery (LIB) recycling processes. This study provides a life cycle impact assessment (LCA) for a hydrometallurgical battery recycling process enhanced with anode material separation via flotation. Life cycle inventory (LCI) was obtained through process simulation, assuming a feed of mixed battery materials including nickel manganese cobalt (NMC), LTO, and graphite. Two scenarios were modeled in which flotation separation was placed before the hydrometallurgical flowsheet (SC1) or, alternatively, placed to treat the leach residue (SC2). For SC1, the battery elements recovery rates were: 85 % Li, 92 % Co, 89 % Ni, 87 % Mn, 89 % Cu and 88 % Ti, whereas for SC2 they were 88 % Li, 94 % Co, 94 % Ni, 90 % Mn, 97 % Cu and 96 % Ti. The LCA results for the organics in solvent extraction (SX) were for SC1 energy resource fossil (ERf) 76 %, eutrophication freshwater (EThf) 71 % and global warming (GW) 69 %, while in SC2 were of 78 % and EThf and GW with 70 %. Acidification (AC) was not affected considerably by the routes, as normalized results showed a difference of < 5 %. Additionally, the simulation results showed that a longer flotation time in SC1 resulted in losses of lithium metal oxides (LMeOs) to the float stream. Nevertheless, although in SC2, EIs were higher compared to SC1, higher recovery yields with minimized waste generation could be demonstrated.

The recycling of silicon solar panels is vital to ensure critical material recovery and to sustain the manufacturing of new panels in line with the United Nations Sustainable Development Goals. While various recycling methods based on thermal, chemical, or mechanical separation of the solar panel layers have been studied, a comprehensive thermodynamic and environmental analysis is required to allow holistic comparison within the circular economy framework. Here, such an analysis is performed for four different silicon solar panel recycling processes. First, the processes were simulated in HSC chemistryTM to analyse the flows of exergy. Subsequently, a Life Cycle Assessment (LCA) was conducted to understand the environmental benefits and drawbacks of each method. Combined Exergy-LCA analysis showed that a slightly less exergy-efficient process, namely pyrolysis can ultimately has the lowest environmental impact out of the four processes. In contrast chemical treatment of the encapsulant exhibited comparably worse performance due to its increased resource consumption. On the material level, high-value material recovery, if realized, could be thermodynamically and environmentally advantageous. The recovery methods presented here could be further improved if heat integration or the use of natural solvents would be considered. These unique findings demonstrate that weighing exergy - Life Cycle Analysis trade-offs across different recycling approaches could navigate future developments towards more sustainable solar panel recycling. Therefore, such an approach is recommended over solely focusing on material recovery.

The rising demand for electric vehicles (EVs) has led to an increased demand for lithium-ion batteries (LIBs). Due to the limited natural sources of battery materials, the need for safe and efficient recycling of LIBs is critical. Batteries at their end-of-life still might have residual energy. Therefore, safe discharge of batteries prior to recycling is needed to minimize the risk of explosion and thermal runaway. This study investigates the electrochemical discharge of LIBs by sodium chloride (NaCl) and potassium carbonate (K2CO3) solutions, with a focus on the impact of discharge current. A novel methodology enables the real-time monitoring of the voltage and current of the battery during electrochemical discharge. This, in turn, can be used to optimize the discharge process for safe and efficient recycling. The results reveal that K2CO3 outperforms the traditionally preferred NaCl electrolyte, providing a higher energy recovery in a shorter time despite retaining higher steady-state voltages (around 76% when 20 wt% K2CO3 was used as a discharge medium). Additionally, an excessive discharge current can lead to overheating and a higher voltage rebound. This should be considered when optimizing the electrochemical discharge process. By balancing the discharge rate, discharge time, and energy recovery, this study provides tools to increase the sustainability and safety of LIB preprocessing before recycling.

Energy transition from fossil- to a material-intensive energy system is highly dependent on the availability of Co and Ni. This has increased interest towards non-traditional raw material streams such as mining waste. In this work, leaching experiments were conducted on historical flotation tailings with low concentrations of Co (0.081 wt%), Ni (0.055 wt%), Cu (0.15 wt%) and Zn (0.17 wt%). This low grade may challenge the feasibility of industrial operation, and therefore water, and commonly used mineral acids, were investigated as lixiviants for the process. The electrochemical leaching behaviour was studied using various oxidants (O-2, Cu2+, Fe3+ and H2O2). The results showed that a substantial amount of Co (21 %) and Ni (37 %) could be leached using water, with no additional oxidants or pH adjustment (80 degrees C, 5 min). In water leaching, the system stabilized inherently to pH=3.7 and the redox potential to E-h < 0.3 V vs Ag/AgCl. This indicates that during the 32-67 years of piling, the weathering conditions had caused natural oxidation of Co- and Ni-bearing minerals such as pyrrhotite and pentlandite. The leaching yields of Co and Ni were slightly increased (5 % units for Co, 10 % units for Ni) by introducing additional acid (1 M) into the leaching system. Further addition of oxidants did not increase the leaching yield of Co, suggesting that the dissolution of Co-bearing minerals followed the chemical leaching mechanism. In contrast, some of the Ni leaching was found to be electrochemical in nature, as extraction increased up to 63 % with the use of strong oxidative (cupric chloride) conditions - most likely due to partial chalcopyrite or pentlandite leaching. Undissolved Co and Ni remained in refractory minerals such as chalcopyrite or pyrite. In addition to Co and Ni, 52 % of Zn and 37 % of Cu were also found to be soluble under acidic conditions. When considering the use of historical flotation tailings as a feed stream in hydrometallurgical processing, direct water leaching may provide an attractive and robust leaching strategy, with spontaneous inherent pH adjustment. An increase in solid-to-liquid ratio or solution circulation (higher acidity) could increase percentual Co and Ni yield and enable enrichment of the target metals in the pregnant leach solution (PLS). If flotation is considered for concentration of Co- and Ni-bearing minerals, water leaching prior to flotation is recommended, to improve both the flotation performance and overall flotation and metal recovery.

The future demands for lithium-ion batteries required for powering the electrification transition in transportation and energy storage will lead to vast amounts of waste, demanding proper end-of-life strategies. As various recycling routes are continuously developed to address this issue, a significant challenge is the fair comparison of processes entailing different unit operations and transformation stages. Indeed, the choice of metallurgical or direct recycling routes results in diverse materials flows and energy demands. To allow a suitable comparison between technologies, this work presents a grave-to-cradle analysis of cathode materials (i.e., lithium cobalt oxide) considering three recycling processes representative of the most popular routes (i.e., pyrometallurgical, hydrometallurgical, and direct recycling). Unlike previously published works, a system-level analysis of both material recovery and energy preservation was carried out using statistical entropy and exergy analysis, respectively. Furthermore, comparison of processes using exentropy, a recently proposed circularity parameter combining both material recovery and energy preservation, was performed for the first time. The results highlight the need of a robust multidimensional analysis of processes to properly determine their suitability according to the needs of the circular economy. When materials and energy preservation were analyzed independently, two different routes were identified as optimal. The need of a robust multidimensional analysis of processes to properly account for the goals of the circular economy is thus highlighted. Exentropy analysis suggested that direct recycling provides the optimum alternative in terms of energy utilization for the recovery of materials.

The safe recycling of spent LIBs is challenging, as they often contain residual energy. Left untreated, this can trigger a thermal runaway and result in disaster during the recycling process. Electrochemical discharge method is an easy and inexpensive method to eliminate this hazard.

While there has been a growing interest on the concept of Circular Economy (CE), its correlation with sustainability remains controversial. In this work, the combination of Statistical Entropy Analysis (SEA) and Life Cycle Assessment (LCA) is proposed as a new methodology to evaluate recycling processes from the perspective of materials circularity and environmental impacts using a Li-ion battery recycling process as a case study. This work addresses the need of quantitative circularity indicators, as SEA evaluates the concentration of materials at a systems level, while LCA measures the environmental impact of recycling processes in comparison with virgin raw materials production. It was found that process optimization points can be found by simultaneously accounting for materials recovery and the LCA categories of global warming potential, ozone depletion and mineral resource scarcity. Furthermore, a strong correlation was found for the first time between the recovery of critical elements and the environmental impact of raw materials production. The proposed methodology thus offers a robust analysis of a product lifecycle that aids in its design and optimization from the CE perspective.

The growing electric vehicle industry has increased the demand for raw materials used in lithium-ion batteries (LIBs), raising concerns about material availability. Froth flotation has gained attention as a LIB recycling method, allowing the recovery of low value materials while preserving the chemical integrity of electrode materials. Furthermore, as new battery chemistries such as lithium titanate (LTO) are introduced into the market, strategies to treat mixed battery streams are needed. In this work, laboratory-scale flotation separation experiments were conducted on two model black mass samples: i) a mixture containing a single cathode (i.e., NMC811) and two anode species (i.e., LTO and graphite), simulating a mixed feedstock prior to hydrometallurgical treatment; and ii) a graphite-TiO2 mixture to reflect the expected products after leaching. The results indicate that graphite can be recovered with > 98 % grade from NMC811-LTO-graphite mixtures. Additionally, it was found that flotation kinetics are dependent on the electrode particle species present in the suspension. In contrast, the flotation of graphite from TiO2 resulted in a low grade product (<96 %) attributed to the significant entrainment of ultrafine TiO2 particles. These results suggest that flotation of graphite should be preferably carried out before hydrometallurgical treatment of black mass.

Spent lithium-ion batteries (SBs) are important sources of valuable and critical raw materials. An integration of battery recycling with well-established primary processes for metals production has many advantages. In this work, the recycling of two battery scrap fractions obtained from mechanical pretreatment was integrated with a Ni-slag cleaning process at laboratory scale. Graphite from SBs acted as the main reductant, and the reduction behavior of major and trace elements was investigated as a function of time at 1350 °C. Major CO and CO2 concentrations, as well as minor amounts of SO2, NO2, CH4, and C2H4, were detected in the off-gas line. The evolution of gases took place within the first minutes of the experiments, which indicated that metal oxide reduction reactions as well as decomposition of the organic binders both happened very rapidly. This result is in line with the analytical results obtained for the slag phase, where the most significant metal oxide reduction was observed to take place within the first 5 to 10 minutes of the experiments. The distribution coefficient values for Co and Ni between metal alloy and slag as well as between matte and slag showed no significant differences when battery scrap fractions with different compositions were used. The addition of Ni-concentrate in the starting mixture resulted in increasing recoveries of Ni and Co, as well as improved settling of the matte phase.

Der European Mining Course (EMC) ist ein internationales dreifach‑M.Sc.-Programm, welches Experten für den Bergbau und angrenzende Industrien ausbildet. Der EMC wird von drei international angesehenen Universitäten, der Aalto University aus Finnland, der RWTH Aachen University aus Deutschland und seit 2023 auch der Montanuniversität Leoben (Österreich) ausgerichtet. Die Studierenden durchlaufen im Rahmen des EMCs jeweils ein Semester an den drei Partneruniversitäten, bevor sie im vierten Semester ihre Masterarbeit zumeist in Kooperation mit der Industrie anfertigen. Nach erfolgreichem Abschluss des EMCs erhalten die Studierenden insgesamt drei M.Sc.-Abschlüsse, einen von jeder Partnerhochschule. Schon seit seiner Gründung 1996 zeichnet sich der EMC durch eine enge Kooperation mit der europäischen Bergbauindustrie aus und stellt so die Relevanz der Ausbildung sicher. Industrievorträge, Exkursionen und Praktika sowie die Möglichkeiten für Abschlussarbeiten bieten praxisnahe Einblicke für die Studierenden. Die Unterstützung der Industriepartner ist zentral durch die Federation of European Mineral Programs (FEMP) organisiert, die als gemeinnützige Stiftung Spenden aus der Industrie einsammelt und verwaltet. Aus den Beiträgen der Industrie werden beispielsweise Stipendien und extra-curriculare Aktivitäten finanziert. Im Gegenzug haben die Unternehmen Zugang zu dem Alumninetzwerk mit mehr als 800 Alumni und die Möglichkeit, sich selbst als attraktiver Arbeitgeber den Studierenden zu präsentieren. Als zweijähriges internationales Masterprogramm mit der Möglichkeit, in drei verschiedenen europäischen Ländern zu studieren, ist der EMC für Studierende äußerst attraktiv und konnte in den Jahren 2023 und 2024 jeweils Rekordbewerberzahlen verzeichnen. Das internationale, integrierte Curriculum des EMCs baut auf die sich ergänzende Expertise seiner Partneruniversitäten. Der EMC umfasst dabei Fächer zu Gebirgsmechanik, Geologie, Aufbereitungstechnik, Bergbaukunde, Maschinentechnik, Betriebswirtschaftslehre, Projektmanagement und diverse bergbauspezifische Fächer zu Wettertechnik, Abbauplanung und Umweltaspekten. Die bisherige Erfolgsgeschichte des EMC ist nur mit der Unterstützung aus der Industrie möglich gewesen. Um auch weiterhin hochqualifizierte Bergbauingenieure auszubilden, sind wir auf neue Kooperationen angewiesen. Weiterführende Informationen unter www.emc-master.eu , Möglichkeiten für Kooperationen unter www.femp.org .

This research article studies selective flocculation as a means for improving flotation of lithium-ion battery active materials using mixtures of pure LiCoO2 (LCO) and graphite. Scanning electron microscopy (SEM) combined with image analysis via density-based spatial clustering of applications with noise (DBSCAN) is presented as a novel method to quantitatively determine the degree of selectivity in a process that applies selective flocculation as a conditioning stage for froth flotation. SEM was shown to provide visual proof of flocculated particles, even in dried froth samples. Under optimal flocculant concentration of 10 g/t only a few flocs were detected in the froth concentrate, suggesting that heteroflocculation of LCO and graphite was minimized under said conditions. Using a flocculant concentration in excess (50 g/t) resulted in multiple flocculated LCO particles within the froth, indicating loss of flocculation selectivity. These results were corroborated by batch flotation experiments, which showed that treating the pulp with 10 g/t flocculant concentration yielded a graphite froth product at a grade of 98.2 %, compared to 98.1 % recovered from a non-flocculated pulp. An excess flocculant concentration led to a drastic reduction in graphite grade. Similar graphite recoveries were observed in all flotation experiments, indicating that the reduced graphite grade with excess flocculant was a result of hydrophobic heteroflocs carrying entrapped LCO to the froth. Proper pH control throughout the experiment prevented a negative influence of flocculation on the kinetics of graphite recovery, which had been reported in earlier research. The results suggest that selective flocculation is a potential method for improving the separation efficiency of graphite from Li-ion battery waste, and that SEM/DBSCAN can be applied for characterization of selectivity in combined flocculationflotation processes.