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Joint recovery of graphite and lithium metal oxides from spent lithium-ion batteries using froth flotation and investigation on process water re-use
Abstract
Spent lithium-ion batteries (LIBs) contain critical raw materials that need to be recovered and recirculated into the battery supply chain. This work proposes the joint recovery of graphite and lithium metal oxides (LMOs) from pyrolyzed black mass of spent LIBs using froth flotation. Since flotation is a water-intensive process, the quality of the aqueous phase directly impacts its performance. In pursuit of an improved water-management strategy, the effect of process water recirculation on black mass flotation is also investigated. The fine fraction (<90 µm) of the black mass from pyrolyzed and crushed spent LIBs was used. After flotation, 85% of the graphite in the overflow product and 80% of the LMOs in the underflow product were recovered. After flotation with 8 wt% solids, the process water contained about 1,000 mg/L Li and accumulated up to 2,600 mg/L Li after three cycles. The flotation with process water showed no significant impact on the recovery and grade of flotation products, suggesting the feasibility of water recirculation in black mass flotation.
... During direct recycling processes, shredding, crushing, and sieving are usually applied to produce a stream containing the high-value electrode components, commonly referred to as "black mass." Subsequently, the separation of anode and cathode should be performed by a physical separation operation, among which froth flotation has been considered as an interesting option by several authors [11][12][13][14][15][16][17][18][19][20][21][22]. Flotation is a unit operation that exploits differences in the wettability of materials. ...
... The composition of the underflow was calculated via mass balance of the LCO content of the froth fractions and the known head grade of the flotation feed. In these calculations, the LCO/graphite head grades were adjusted based on the assumption that Li partially dissolves in the process water during flotation, as has been documented by other researchers [21]. The dissolution tendency of Li was measured by dispersing a model black mass sample in water (pH 5) under similar mechanical conditions as those applied in the flotation experiments and measuring the mass loss of the sample. ...
... The dissolution tendency of Li was measured by dispersing a model black mass sample in water (pH 5) under similar mechanical conditions as those applied in the flotation experiments and measuring the mass loss of the sample. The recorded mass loss equated to 45 wt.-% of Li dissolving in the process water during one flotation experiment, which coincides with the work of Salces et al. [21]. This equates to an adjusted black mass composition of 49.19 wt.-% cathode material (partially delithiated), and 50.81 wt.-% graphite after flotation. ...
The recycling of active materials from Li-ion batteries (LIBs) via froth flotation has gained interest recently. To date, recycled graphite has not been pure enough for direct reuse in LIB manufacturing. The present work studied the effect of particle sizes on the grade of recycled graphite. Furthermore, selective flocculation is proposed as a novel approach to control particle sizes and thus improve graphite grade by preventing the entrainment of cathode components. Zeta potential and particle size measurements were performed to find an optimal pH for electrically selective flocculation and to study the interaction of flocculants, respectively. Batch flotation experiments were performed to investigate the effect of particle size on the purity of the recovered graphite. Results suggested that, in the absence of ultrafine fine particles, battery-grade graphite of 99.4% purity could be recovered. In the presence of ultrafine particles, a grade of 98.2% was observed. Flocculating the ultrafine feed increased the grade to 98.4%, although a drop in recovery was observed. By applying a dispersant in addition to a flocculant, the recovery could be increased while maintaining a 98.4% grade. Branched flocculants provided improved selectivity over linear flocculants. The results suggest that particle size needs to be controlled for battery-grade graphite to be recovered.
... Moreover, even with full discharge, there is still a portion of "dead lithium" in the anode. Part of this "dead lithium" comes from lithium that cannot be released from the graphite layers, and this part of the lithium will dissolve in the slurry during flotation and become impurity ions that affect flotation [47,48]. Another part comes from the SEI film produced on the graphite surface during battery cycling. ...
The recycling of spent lithium-ion batteries (LIBs) has attracted great attention, mainly because of its significant impact on resource recycling and environmental protection. Currently, the processes involved in recovering valuable metals from spent LIBs have shown remarkable progress, but little attention has been paid to the effective separation of spent cathode and anode materials. Significantly, it not only can reduce the difficulty in the subsequent processing of spent cathode materials, but also contribute to the recovery of graphite. Considering the difference in their chemical properties on the surface, flotation is an effective method to separate materials, owing to its low-cost and eco-friendly characteristics. In this paper, the chemical principles of flotation separation for spent cathodes and materials from spent LIBs is summarized first. Then, the research progress in flotation separation of various spent cathode materials (LiCoO2, LiNixCoyMnzO2, and LiFePO4) and graphite is summarized. Given this, the work is expected to offer the significant reviews and insights about the flotation separation for high-value recycling of spent LIBs.
With the exponential expansion of electric vehicles (EVs), the disposal of Li-ion batteries (LIBs) is poised to increase significantly in the coming years. Effective recycling of these batteries is essential to address environmental concerns and tap into their economic value. Direct recycling has recently emerged as a promising solution at the laboratory level, offering significant environmental benefits and economic viability compared to pyrometallurgical and hydrometallurgical recycling methods. However, its commercialization has not been realized in the terms of financial feasibility. This perspective provides a comprehensive analysis of the obstacles that impede the practical implementation of direct recycling, ranging from disassembling, sorting, and separation to technological limitations. Furthermore, potential solutions are suggested to tackle these challenges in the short term. The need for long-term, collaborative endeavors among manufacturers, battery producers, and recycling companies is outlined to advance fully automated recycling of spent LIBs. Lastly, a smart direct recycling framework is proposed to achieve the full life cycle sustainability of LIBs.
Pyrolysis is an effective method for removing organic contaminants (e.g. electrolytes, solid electrolyte interface (SEI), and polyvinylidene fluoride (PVDF) binders) from spent lithium-ion batteries (LIBs). However, during pyrolysis, the metal oxides in black mass (BM) readily react with fluorine-containing contaminants, resulting in a high content of dissociable fluorine in pyrolyzed BM and fluorine-containing wastewater in subsequent hydrometallurgical processes. Herein, an in-situ pyrolysis process is proposed to control the transition pathway of fluorine species in BM using Ca(OH)2-based materials. Results show that the designed fluorine removal additives (FRA@Ca(OH)2) can effectively scavenge SEI components (LixPOFy) and PVDF binders from BM. During the in-situ pyrolysis, potential fluorine species (e.g. HF, PF5, and POF3) are adsorbed and converted to CaF2 on the surface of FRA@Ca(OH)2 additives, thereby inhibiting the fluorination reaction with electrode materials. Under the optimal experimental conditions (temperature = 400 °C, BM: FRA@Ca(OH)2 = 1: 4, holding time = 1.0 h), the dissociable fluorine content in BM was reduced from 3.84 wt% to 2.54 wt%. The inherent metal fluorides in BM feedstock hinder the further removal of fluorine with pyrolysis treatment. This study provides a potential strategy for source control of fluorine-containing contaminants in the recycling process of spent LIBs.
With the constant growth in portable electronic devices and the expected market growth for electric vehicles, the demand for lithium-ion batteries (LIBs) is booming. The raw materials production with a combination of mining and recycling will be essential and unavoidable to meet the upcoming demand for LIBs. Consequently, the European authority is updating the regulations demanding higher recovery efficiencies, 70 % by 2030. However, most of the state-of-the-art recycling technologies for LIBs focus on the recovery of components that have high economic value such as Co and Ni. The fine fraction resulting from the mechanical pre-treatment containing the lithium metal oxides (LMOs) and graphite particles, commonly referred to as "Black Mass" (BM), is generally used as a starting point for metals recovery by metallurgical means. Indeed, in industry, this BM is usually not further sorted and is directly fed to pyro- and/or hydrometallurgical processing routes to extract metals from LMOs, at the expense of graphite not being recovered. Recent studies, however, have convincingly illustrated that froth flotation can be applied to the BM to efficiently generate two valuable products, therefore increasing the overall efficiency of LIB recycling significantly. The work presented in this thesis aims to increase the overall materials recovery from LIBs by improving the BM beneficiation through froth flotation. The research work hereby presented offers a systematic study of the influence of the recycling pre-treatment processes on the liberation of the LIB components and the potential flotation mechanisms of active particles. The first part of this thesis is focused on the liberation analysis of the LIB components, which cannot be determined by conventional bulk characterization techniques such as X-ray fluorescence. In this thesis, a new approach for the BM characterization using automated mineralogy has been developed. With this particle-based technique, information on the chemical composition, morphology and degree of liberation of LIB components was acquired, helping to understand how the particles behaved during the process. The second part is focused on BM beneficiation on the basis of flotation. The use of flotation has recently gained interest as a method to separate LMOs and graphite particles. However, the flotation mechanisms of LMOs have not been paid sufficient attention. Therefore, this work provides the first fundamental study on the flotation mechanisms of active particles, with the aim of properly identifying the challenges to overcome in order to drive selectivity in flotation separation. To understand the flotation behavior, an industrial BM from pyrolyzed LIBs was compared to a model BM, comprising fully liberated LMOs and graphite particles. In addition, ultrafine hydrophilic particles were added to the flotation feed as an entrainment tracer, showing that the LMOs recovery in overflow products is a combination of entrainment and true flotation mechanisms. Ultimately, the findings of this thesis indicate the possibility of recovering and reusing graphite into new batteries.
Recycling is a potential solution to narrow the gap between the supply and demand of raw materials for lithium-ion batteries (LIBs). However, the efficient separation of the active components and their recovery from battery waste remains a challenge. This paper evaluates the influence of three potential routes for the liberation of LIB components (namely mechanical, thermomechanical, and electrohydraulic fragmentation) on the recovery of lithium metal oxides (LMOs) and spheroidized graphite particles using froth flotation. The products of the three liberation routes were characterized using SEM-based automated image analysis. It was found that the mechanical process enabled the delamination of active materials from the foils, which remained intact at coarser sizes along with the casing and separator. However, binder preservation hinders active material liberation, as indicated by their aggregation. The electrohydraulic fragmentation route resulted in liberated active materials with a minor impact on morphology. The coarse fractions thus produced consist of the electrode foils, casing, and separator. Notwithstanding, it has the disadvantage of forming heterogeneous agglomerates containing liberated active particles. This was attributed to the dissolution of the anode binder and its rehardening after drying, capturing previously liberated particles. Finally, the thermomechanical process showed a preferential liberation of individual anode active particles and thus was considered the preferred upstream route for flotation. However, the thermal treatment oxidized Al foils, rendering them brittle and resulting in their distribution in all size fractions. Among the three, the thermomechanical black mass showed the highest flotation selectivity due to the removal of the binder, resulting in a product recovery of 94.4% graphite in the overflow and 89.4% LMOs in the underflow product.
One of the main tasks to ensure the secure supply of critical raw materials is the efficient recovery and recycling of secondary resources. Lithium-ion batteries (LIB) are the key technology nowadays and in the future to enable the human energy revolution. Therefore, the recycling of spent LIBs is of great interest. A major challenge in spent LIBs recycling, is the beneficiation of fine powder resulting from the battery crushing, so-called “black mass”, which contains the valuable lithium metal oxides (from the cathode) and the critical graphite (from the anode). One promising way to separate the graphitic material from the lithium metal oxides is by means of froth flotation, which separates the particles according to their differences in wettability. In order to improve the separation process, one must first have a proper understanding of the particle properties. In particular, the lithium metal oxides are commonly declared as hydrophilic and should therefore be easily separated from the hydrophobic graphite. Nevertheless, many studies report on their recovery into the froth product, along with the graphite, thus lowering its grade, which is most probably due to the residual hydrophobic binder that causes a change in their wettability.
In this study, different battery materials, including pristine lithium metal oxides and graphite, as well as real spent materials from LIBs wastes were used. The micro particles were analysed for their wettability and (de)wetting ability using optical contour analysis, inverse gas chromatography, particle attachment to bubbles, analytical particle solvent extraction as well as the famous Washburn method. These results are set into context with flotation tests and shed light on the particle wettability and its effect on the flotation separation efficiency, as well as the difficulties that arise when it comes to the recycling of spent LIBs.
This work investigates the comprehensive recycling of graphite and cathode active materials (LiNi0.6Mn0.2Co0.2O2, abbreviated as NMC) from spent lithium-ion batteries via pretreatment and flotation. Specific analytical methods (SPME-GC-MS and Py-GC-MS) were utilized to identify and trace the relevant influencing factors. Two different pretreatment methods, which are Fenton oxidation and roasting, were investigated with respect to their influence on the flotation effectiveness. As a result, for NMC cathode active materials, a recovery of 90% and a maximum grade of 83% were obtained by the optimized roasting and flotation. Meanwhile, a graphite grade of 77% in the froth product was achieved, with a graphite recovery of 75%. By using SPME-GC-MS and Py-GC-MS analyses, it could be shown that, in an optimized process, an effective destruction/removal of the electrolyte and binder residues can be reached. The applied analytical tools could be integrated into the workflow, which enabled process control in terms of the pretreatment sufficiency and achievable separation in the subsequent flotation.
The comminution of spent lithium-ion batteries (LIBs) produces a powder containing the
active cell components, commonly referred to as “black mass.” Recently, froth flotation has been proposed to treat the fine fraction of black mass (<100 �m) as a method to separate anodic graphite particles from cathodic lithium metal oxides (LMOs). So far, pyrolysis has been considered as an effective treatment to remove organic binders in the black mass in preparation for flotation separation. In this work, the flotation performance of a pyrolyzed black mass obtained from an industrial recycling plant was improved by adding a pre-treatment step consisting of mechanical attrition with and without kerosene addition. The LMO recovery in the underflow product increased from 70% to 85% and the graphite recovery remained similar, around 86% recovery in the overflow product.
To understand the flotation behavior, the spent black mass from pyrolyzed LIBs was compared to a model black mass, comprising fully liberated LMOs and graphite particles. In addition, ultrafine hydrophilic particles were added to the flotation feed as an entrainment tracer, showing that the LMO recovery in overflow products is a combination of entrainment and true flotation mechanisms. This study highlights that adding kerosene during attrition enhances the emulsification of kerosene, simultaneously increasing its (partial) spread on the LMOs, graphite, and residual binder, with a subsequent reduction in selectivity.
Selective leaching of Li from spent LIBs thermally pretreated by pyrolysis and incineration between 400 and 700 °C for 30, 60, and 90 min followed by water leaching at high temperature and high L/S ratio was examined. During the thermal pretreatment Li2CO3 and LiF were leached. Along with Li salts, AlF3 was also found to be leached with an efficiency not higher than 3.5%. The time of thermal pretreatment did not have a significant effect on Li leaching efficiency. The leaching efficiency of Li was higher with a higher L/S ratio. At a higher leaching temperature (80 °C), the leaching of Li was higher due to an increase in the solubility of present Li salts. The highest Li leaching efficiency of nearly 60% was observed from the sample pyrolyzed at 700 °C for 60 min under the leaching condition L/S ratio of 20:1 mL g−1 at 80 °C for 3 h. Furthermore, the use of an excess of 10% of carbon in a form of graphite during the thermal treatment did not improve the leaching efficiency of Li.
Mechanical recycling processes aim to separate particles based on their physical properties, such as size, shape and density, and physico-chemical surface properties, such as wettability. Secondary materials, including electronic waste, are highly complex and heterogeneous, which complicates recycling processes. In order to improve recycling efficiency, characterization of both recycling process feed materials and intermediate products is crucial. Textural characteristics of particles in waste mixtures cannot be determined by conventional characterization techniques, such as X-ray fluorescence and X-ray diffraction spectroscopy. This paper presents the application of automated mineralogy as an analytical tool, capable of describing discrete particle characteristics for monitoring and diagnosis of lithium ion battery (LIB) recycling approaches. Automated mineralogy, which is well established for the analysis of primary raw materials but has not yet been tested on battery waste, enables the acquisition of textural and chemical information, such as elemental and phase composition, morphology, association and degree of liberation. For this study, a thermo-mechanically processed black mass (<1 mm fraction) from spent LIBs was characterized with automated mineralogy. Each particle was categorized based on which LIB component it comprised: Al foil, Cu foil, graphite, lithium metal oxides and alloys from casing. A more selective liberation of the anode components was achieved by thermo-mechanical treatment, in comparison to the cathode components. Therefore, automated mineralogy can provide vital information for understanding the properties of black mass particles, which determine the success of mechanical recycling processes. The introduced methodology is not limited to the presented case study and is applicable for the optimization of different separation unit operations in recycling of waste electronics and batteries.
The expected rapid growth in electric vehicle deployment will inevitably be followed by a corresponding rise in the supply of end-of-life vehicles and their lithium-ion batteries (LIBs). The batteries may be reused, but will eventually be spent and provide a potential domestic resource that can help supply materials for future battery production. However, commercial recycling processes depend on profits from recovery of cobalt, use of which is being reduced in new cathode chemistries. The U.S. Department of Energy, therefore, established the ReCell Center in early 2019 to develop robust LIB recycling technology that would be economical even for batteries that contain no cobalt. The central feature of the technology is recovery of the cathode material with its unique crystalline cathode morphology intact in order to retain its value and functionality. Other materials are recovered as well in order to maximize revenues and minimize waste-handling costs. Analysis and modeling serve to evaluate and compare process options so that we can identify those that will be most economical while still minimizing energy use and environmental impacts. This paper provides background and describes highlights of the center’s first 2 years of operation.
Froth flotation is a multifaceted complex process which is water intensive. The use of recycled water as an alternative source of water to meet water demands of the process may introduce deleterious inorganic ions that affect the mineral surface, pulp chemistry, and reagent action, hence the need to establish whether threshold ion concentrations exist beyond which flotation performance will be adversely affected. This is of paramount importance in informing appropriate recycle streams and allowing simple, cost-effective water treatment methods to be applied. Here we report that increasing ionic strengths of synthetic plant water (SPW); 3, 5, and 10 SPW respectively, resulted in an increase in water recovery in the order 0.073 mol·dm −3 (3 SPW) < 0.121 mol·dm −3 (5 SPW) < 0.242 mol·dm −3 (10 SPW), indicating an increase in froth stability as higher water recoveries are linked to increased froth stabilities. This behavior is linked to the action of inorganic electrolytes on bubble coalescence which is reported in literature. There was, however, no significant effect on the valuable mineral recovery. Spiking 3 SPW to 400 mg/L Ca 2+ resulted in higher copper and nickel grades compared to 3 SPW, 5 SPW, and 10 SPW and was deemed to be the Ca 2+ ion threshold concentration for this study since 3 SPW spiked with further Ca 2+ to a concentration of 800 mg/L resulted in a decrease in the concentrate grade. The spiking of 3 SPW with Mg 2+ resulted in higher copper and nickel grades compared to all other synthetic plant water conditions tested in this study.
Thermal treatment offers an alternative method for the separation of Al foil and cathode materials during spent lithium-ion batteries (LIBs) recycling. In this work, the pyrolysis behavior of cathode from spent LIBs was investigated using advanced thermogravimetric Fourier transformed infrared spectroscopy coupled with gas chromatography-mass spectrometer (TG-FTIR-GC/MS) method. The fate of fluorine present in spent batteries was probed as well. TG analysis showed that the cathode decomposition displayed a three-stage process. The temperatures of maximum mass loss rate were located at 470 °C and 599 °C, respectively. FTIR analysis revealed that the release of CO2 increased as the temperature rose from 195 to 928 °C. However, the evolution of H2O showed a decreasing trend when the temperature increased to above 599 °C. The release of fluoride derivatives also exhibited a decreasing trend, and they were not detected after temperatures increasing to above 470 °C. GC-MS analysis indicated that the release of H2O and CO displayed a similar trend, with larger releasing intensity at the first two stages. The evolution of 1,4-difluorobenzene and 1,3,5-trifluorobenzene also displayed a similar trend—larger releasing intensity at the first two stages. However, the release of CO2 showed a different trend, with the largest release intensity at the third stage, as did the release of 1,2,4-trifluorobenzene, with the release mainly focused at the temperature of 300–400 °C. The release intensities of 1,2,4-trifluorobenzene and 1,3,5-trifluorobenzene were comparable, although smaller than that of 1,4-difluorobenzene. This study will offer practical support for the large-scale recycling of spent LIBs.
The recycling of spent lithium-ion batteries (LIB) is becoming increasingly important with regard to environmental, economic, geostrategic, and health aspects due to the increasing amount of LIB produced, introduced into the market, and being spent in the following years. The recycling itself becomes a challenge to face on one hand the special aspects of LIB-technology and on the other hand to reply to the idea of circular economy. In this paper, we analyze the different recycling concepts for spent LIBs and categorize them according to state-of-the-art schemes of waste treatment technology. Therefore, we structure the different processes into process stages and unit processes. Several recycling technologies are treating spent lithium-ion batteries worldwide focusing on one or several process stages or unit processes.
Abstract Worldwide trends in mobile electrification, largely driven by the popularity of electric vehicles (EVs) will skyrocket demands for lithium‐ion battery (LIB) production. As such, up to four million metric tons of LIB waste from EV battery packs could be generated from 2015 to 2040. LIB recycling directly addresses concerns over long‐term economic strains due to the uneven geographic distribution of resources (especially for Co and Li) and environmental issues associated with both landfilling and raw material extraction. However, LIB recycling infrastructure has not been widely adopted, and current facilities are mostly focused on Co recovery for economic gains. This incentive will decline due to shifting market trends from LiCoO2 toward cobalt‐deficient and mixed‐metal cathodes (eg, LiNi1/3Mn1/3Co1/3O2). Thus, this review covers recycling strategies to recover metals in mixed‐metal LIB cathodes and comingled scrap comprising different chemistries. As such, hydrometallurgical processes can meet this criterion, while also requiring a low environmental footprint and energy consumption compared to pyrometallurgy. Following pretreatment to separate the cathode from other battery components, the active material is dissolved entirely by reductive acid leaching. A complex leachate is generated, comprising cathode metals (Li+, Ni2+, Mn2+, and Co2+) and impurities (Fe3+, Al3+, and Cu2+) from the current collectors and battery casing, which can be separated and purified using a series of selective precipitation and/or solvent extraction steps. Alternatively, the cathode can be resynthesized directly from the leachate.
Direct recycling of lithium-ion is a promising method for manufacturing sustainability. It is more efficient than classical methods because it recovers the functional cathode particle without decomposition into substituent elements or dissolution and precipitation of the whole particle. This case study of cathode-healing™ applied to a battery recall demonstrates an industrial model for recycling of lithium-ion, be it consumer electronic or electric vehicle (EV) batteries. The comprehensive process includes extraction of electrolyte with carbon dioxide, industrial shredding, electrode harvesting, froth flotation, cathode-healing™ and finally, building new cells with recycled cathode and anode. The final products demonstrated useful capability in the first full cells made from direct recycled cathodes and anodes from an industrial source. The lessons learned on recycling the prototypical chemistry are preliminarily applied to EV relevant chemistries.
Lithium-ion batteries (LIBs) are currently one of the most important electrochemical energy storage devices, powering electronic mobile devices and electric vehicles alike. However, there is a remarkable difference between their rate of production and rate of recycling. At the end of their lifecycle, only a limited number of LIBs undergo any recycling treatment, with the majority go to landfills or being hoarded in households. Further losses of LIB components occur because the the state-of-the-art LIB recycling processes are limited to components with high economic value, e.g., Co, Cu, Fe, and Al. With the increasing popularity of concepts such as “circular economy” (CE), new LIB recycling systems have been proposed that target a wider spectrum of compounds, thus reducing the environmental impact associated with LIB production. This review work presents a discussion of the current practices and some of the most promising emerging technologies for recycling LIBs. While other authoritative reviews have focused on the description of recycling processes, the aim of the present was is to offer an analysis of recycling technologies from a CE perspective. Consequently, the discussion is based on the ability of each technology to recover every component in LIBs. The gathered data depicted a direct relationship between process complexity and the variety and usability of the recovered fractions. Indeed, only processes employing a combination of mechanical processing, and hydro- and pyrometallurgical steps seemed able to obtain materials suitable for LIB (re)manufacture. On the other hand, processes relying on pyrometallurgical steps are robust, but only capable of recovering metallic components.
In light of the increasing penetration of electric vehicles (EVs) in the global vehicle market, understanding the environmental impacts of lithium-ion batteries (LIBs) that characterize the EVs is key to sustainable EV deployment. This study analyzes the cradle-to-gate total energy use, greenhouse gas emissions, SOx, NOx, PM10 emissions, and water consumption associated with current industrial production of lithium nickel manganese cobalt oxide (NMC) batteries, with the battery life cycle analysis (LCA) module in the Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation (GREET) model, which was recently updated with primary data collected from large-scale commercial battery material producers and automotive LIB manufacturers. The results show that active cathode material, aluminum, and energy use for cell production are the major contributors to the energy and environmental impacts of NMC batteries. However, this study also notes that the impacts could change significantly, depending on where in the world the battery is produced, and where the materials are sourced. In an effort to harmonize existing LCAs of automotive LIBs and guide future research, this study also lays out differences in life cycle inventories (LCIs) for key battery materials among existing LIB LCA studies, and identifies knowledge gaps.
Previous studies speculate that hydroxo species present in flotation pulps at pH > 9, particularly those of polyvalent cations, selectively adsorb onto gangue minerals. Such species supposedly enhance the depressive action of carboxymethyl cellulose (CMC) onto gangue via an acid-base interaction between the positively charged mineral surface and the negatively charged CMC molecule. Thus, the hydrophilicity of gangue minerals is enhanced, preventing the dilution of the concentrate. However, as there is little evidence to support these claims for complex process waters of increasing ionic strength, it is important to investigate. Adsorption data and mineral surface charge analyses provide a fundamental understanding of how electrolytes and their ionic strengths affect gangue mineral-depressant adsorption. It is strongly anticipated that decoupling these effects will allow process operators to tailor their process water quality needs towards best flotation operating regimes and, in the long run, effect closed water circuits. Thus, using talc as a proxy for naturally floatable gangue common in sulfidic Cu–Ni–PGM ores, this work investigates the influence of the ionic strength of process water on the adsorption of CMC onto talc for a perspective on how saline water in sulfidic ores would affect the behavior and therefore management of floatable gangue. In the presence of CMC, the microflotation results showed that the rate of talc recovery decreased with increasing ionic strength of process water. Increases in ionic strength resulted in an increase in the adsorption of CMC onto talc. Talc particles proved to have been more coagulated at higher ionic strength since the settling time decreased with increasing ionic strength. Furthermore, the zeta potential of talc particles became less negative at higher ionic strengths of process water. It is thus proposed that increases in the ionic strength of process water increased the zeta potential of talc particles, enhancing the adsorption of CMC onto talc. This in turn created a more coagulated nature on talc particles, increasing their hydrophilicity and thereby retarding floatability.
Spent lithium-ion batteries(LIBs) contain lots of valuable metals such as nickel, cobalt, and lithium, together with organic solvents, binders, and other toxic materials. Therefore, recycling of spent LIBs is of great importance for comprehensive resource recovery and environmental protection. In this study, vacuum pyrolysis was used to dispose of the cathode sheets of LIBs. The effects of pyrolysis temperature and vacuum degree on the separation of cathode sheets and phase transition of valuable metal of cathode active powder were investigated in detail. The results showed that the effective separation of active powder and Al foil can be achieved under the optimized conditions of pyrolysis temperature of 600 °C and a vacuum degree of 1000 Pa, and the recovery rate of cathode active powder reached 98.04%. In the temperature range of 450–650 °C, with the increase of pyrolysis temperature, the XRD patterns of the cathode active powder showed that the characteristic peak of Li[Ni x Co y Mn 1-x-y ]O 2 gradually weakened and eventually disappeared.
The present work offers a study on the engineering implications of the recovery of valuable fractions from industrially collected lithium battery (LIB) waste by mechanical and hydrometallurgical processes in HCl media. Direct leaching of LIB waste provides a possibility for Li extraction, a component that is lost into the slag fraction in the state-of-art high temperature processes. The challenges arising from the heterogeneous composition of industrial battery waste are highlighted, and the behavior of main metals present such as Co, Cu, Li, Mn, Ni and Al is observed. It is shown that mechanical separation processes can form fractions rich on Cu and Al, although subsequent refining stages are necessary. Regarding direct leaching, fast kinetics were found, as complete Li dissolution can be achieved in ca. 120 min. Furthermore, high solid/liquid ratio (>1/10) is required to increase metal value concentrations, resulting in a viscous slurry due to the graphite, plastics and other undissolved materials, which challenges filtration and washing of leach residue. Neutralization of the product liquid solution (PLS) result in co-precipitation of valuable battery metals along with Fe and Al. The highest value of LIBs lies in Co, subjected for solvent extraction (SX) or direct precipitation to make an intermediate product. SX can provide selectivity whereas Na2CO3 precipitation provides a fast route for Co-Ni bulk production. Li2CO3 precipitation from the remaining PLS is possible as zabuyelite - however, due to heterogeneity of the battery waste, the recovery of Li2CO3 with battery-grade purity remains a difficult task to be achieved by direct precipitation route.
The primary goal of this study is to investigate the effect of increasing battery size and driving range to the environmental impact of electric vehicles (EVs). To this end, we compile cradle-to-grave inventories for EVs in four size segments to determine their climate change potential. A second objective is to compare the lifecycle emissions of EVs to those of conventional vehicles. For this purpose, we collect lifecycle emissions for conventional vehicles reported by automobile manufacturers. The lifecycle greenhouse gas emissions are calculated per vehicle and over a total driving range of 180 000 km using the average European electricity mix. Process-based attributional LCA and the ReCiPe characterisation method are used to estimate the climate change potential from the hierarchical perspective. The differently sized EVs are compared to one another to find the effect of increasing the size and range of EVs. We also point out the sources of differences in lifecycle emissions between conventional- and electric vehicles. Furthermore, a sensitivity analysis assesses the change in lifecycle emissions when electricity with various energy sources power the EVs. The sensitivity analysis also examines how the use phase electricity sources influences the size and range effect.
A water soluble polymer poly(diethylene glycol methyl ether methacrylate) (PMeO2MA) is grafted on poly(vinylidene fluoride) (PVDF) backbone via a coupled atom transfer radical coupling (ATRC) followed by atom transfer radical polymerization (ATRP). The PVDF-g- PMeO2MA copolymers are designated as PD-24, PD-16 etc depending on polymerization time and are characterized using 1H NMR spectra, FTIR spectra and gel permeation chromatography. AFM images indicate a change in morphology from spherulitic PVDF to the self-organized nano-sphere morphology with hairy PMeO2MA chains at the surface corona. TGA data of PD graft copolymers indicate two stage degradations which temperatures are higher from the components. The glass transition temperatures of the PD graft copolymers are higher from PMeO2MA, and both melting point & crystallinity decrease progressively with increase of graft conversion. Dynamic light scattering (DLS) data indicate that PD graft copolymers possess a lower critical solution temperature (LCST) at ~30 0C which can be tuned by changing the composition of the graft copolymer. The antifouling properties of the PD-24 film, produced specially by water treatment at 15 0C (PD-24-15) and 370C (PD-24-37), are tested with bovine serum albumin (BSA) at below and above LCST and a lower protein adsorption is noticed at 37 0C indicating a temperature triggered antifouling property of the PD graft co-polymers. The surface hydrophilicity of the graft copolymer, measured from the contact angle measurement, is higher in the PD graft co-polymer from PVDF and the contact angle decreases more significantly for PD-24-15 film than that of PD-24-37 film with time. The filtration of BSA solution using these two films and monitoring through fluorescence intensity indicates ~60% protein absorption during filtration through the PD-24-15 film but PD-24-37 do not exhibit any change of fluorescence intensity, indicating superior antifouling property.
From the perspective of environmental protection and resource recovery, recycling of spent lithium-ion batteries is a meaningful process. In this study, the removal of organics, liberatioin of electrode material, and reduction of high valence transition metal, as the key points in recycling efficiency of valuable metals, have been firstly achieved simultaneously by low temperature heat treatment recycling process. Pyrolysis characteristics of organics, phase transition behavior of spent cathode material and the thermal reduction mechanism were evaluated in the meantime. Results demonstrate that organics can be removed and the liberation of electrode materials can be improved by pyrolysis. High-valence transition metals in cathode materials are synchronously reduced to CoO, NiO, MnO, Ni, and Co based on the reducing action of organics, aluminum foil and conductive additives. At the same time, Li element exists in the form of Li2CO3, LiF and aluminum-lithium compound that can be recycled by water-leaching in the water impact crushing process while transition metals can be recycled by acid leaching without reducing agents. 81.26% of Li can be recycled from water-leaching process while the comprehensive recovery rate of Ni, Co, Mn is 92.04%, 93.01%, 92.21%, respectively. This study may provide an environmentally-friendly recycling flowchart of spent lithium-ion batteries.
The treatment of end-of-life lithium-ion batteries (LIBs) using froth flotation has recently gained interest as a method to separate valuable lithium transition-metal oxides (LMOs) and graphite particles from the so-called “black mass” mixture. However, the flotation mechanisms of the cathode active particles have not been properly discussed so far, likely since they are generally accepted to be hydrophilic and are thus expected to remain suspended in the bulk phase and recovered in the underflow. Nevertheless, the froth phase products reported in the literature often contain more than 10% LMOs. This results in losses of cathode materials, while hampering the quality of the recovered anode components. As graphite is one of the main materials used for anode manufacturing, being categorized as a critical raw material, its recovery plays an essential role in the electric vehicle revolution.
This work provides the first fundamental study on the flotation mechanisms of the fine particulate black mass components, with the aim of properly identifying the challenges to overcome in order to drive selectivity in froth flotation separation. A series of analysis using model black mass were carried out to circumvent the influence of residual hydrophobic binder found in LIB waste. Studies of wettability with captive bubble and Washburn capillary rise methods show contact angles for LMOs varying from 14° to 52.6° depending on the technique used. Using a bubble-particle attachment set-up it was found that LMO particles can attach to air bubbles spontaneously and in measurable quantities, contrary to the commonly assumed hydrophilic character of cathode active particles. It was also observed that the typically used oil-based collectors (e.g., Escaid 110) interact with both spheroidized graphite and lithium metal oxides, increasing their hydrophobicity and promoting agglomeration. Finally, the particle agglomeration of black mass components provides another flotation mechanism for LMOs through entrapment.
The demand for lithium has skyrocketed in recent years primarily due to three international treaties—Kyoto Protocol, Paris Agreement and UN Sustainable Development Goals—all of which are pushing for the integration of more renewable energy and clean storage technologies in the transportation and electric power sectors to curb CO2 emissions and limit the adverse effects of CO2-promoted climate change. Over 60% of lithium produced in 2019 were utilised for the manufacture of lithium-ion batteries (LIBs), the compact and high-density energy storage devices crucial for low-carbon emission electric-based vehicles (EVs) and secondary storage media for renewable energy sources like solar and wind. In 2019, the global market value of lithium reached around US$213 B and is forecasted to grow by around 20–25% until 2025. In this review, the current state of global lithium resources, global lithium material flow, and forecasts of future lithium supply–demand dynamics are discussed. Persistent challenges in mining, processing and industrial-scale recycling operations are also examined and recent innovations to address these issues are introduced. Finally, unconventional lithium sources like submarine/deep-sea ferromanganese (Fe-Mn) nodules and crusts, industrial wastes (e.g., desalination brines, geothermal brines and coal fly ashes), mining wastes and effluents, and extra-terrestrial materials are explored.
The separation of electrode active materials from spent Li-ion batteries (LIBs) by froth flotation is challenging due to the changes in surface properties of electrode active materials from cycling as well as the presence of organic binders. In this work, the froth flotation separation of aged anode and cathode composite materials from spent LIBs was systematically investigated after the materials were heat treated. The results show that aged anode and cathode materials from spent LIBs can be well separated from each other after a heating process in air at 400 °C and at which some of the PVDF binder remains intact. The underlying mechanism was investigated by X-ray photoelectron spectroscopy (XPS), contact angle measurements, and scanning transmission electron microscopy (STEM) coupled with energy-dispersive X-ray spectroscopy (EDX). The results from the XPS and contact angle measurements show that there is a hydrophilic and oxygen-rich layer on the surface of aged anode materials. This hydrophilic surface, associated with the solid electrolyte interface (SEI) layer, impacts the froth flotation process significantly. The results also show that both the SEI layers and PVDF binder residues on the surface are removed at 400 °C for an hour, restoring the hydrophobicity of the anode materials, which, in turn, benefits the separation of anode and cathode materials. The STEM/EDX elemental analysis data confirms that there are 20 nm-thick oxygen-rich SEI layers on the surfaces, which can be removed after a heating process. The present result illustrates the significance of the SEI layers in flotation separation of electrode materials and sheds new lights into the future development of the recycling processes for the separation of anode and cathode composite materials from spent Li-ion batteries.
A novel method of cryogenic grinding and froth flotation is proposed to recover LiCoO2 and graphite from spent lithium-ion batteries. After 9 min of cryogenic grinding, the grade of LiCoO2 concentrate was up to 91.75%, with a recovery rate of 89.83% after flotation, but the materials that have not been cryogenic grinding, the grade and recovery rate of LiCoO2 after flotation only 55.36% and 72.8%, respectively. Analysis of the surface properties and morphology of electrode particles was performed using scanning electron microscopy, X-ray photoelectron spectroscopy, and field emission-electron probe micro-analysis. Results indicate that the organic binder on the surface of the raw materials resulted in a poor recovery rate and grade of the flotation concentrate. Cryogenic grinding, on the other hand, caused the organic binder on the surface of electrode materials to peel off, with spherical graphite changing into a scaly layer structure that revealed a new surface. The hydrophilicity of LiCoO2 and hydrophobicity of graphite were obviously improved by cryogenic grinding, and in turn contributed to an excellent flotation separation. This work provides an efficient and environmentally-friendly process for recovering LiCoO2 and graphite from spent lithium-ion batteries.
Direct recycling of Li-ion batteries (LIBs) reclaims electrode materials using physical separation followed by materials' rejuvenation processes. The cathode composites in LIBs contain both carbon black and PVDF binders in its chemistry. For the rejuvenation process to work, an ability to remove these impurities is desirable. In the present work, de-agglomeration of individual components from the cathode composites has been carried out using a mechanical process that is developed for preserving functional integrity of the cathode active materials. It has been shown that the size of the cathode composites is effectively reduced upon a de-agglomeration process due to a liberation of PVDF binders from the cathode composites. The de-agglomeration performance has been evaluated by separating mixed materials by the degree in surface hydrophobicity using the froth flotation method. The performance improves with end-of-life (EOL) LIBs compared to new LIBs, benefiting from a degradation of PVDF binders after charging-discharging cycles. X-ray photoelectron spectra suggests that the de-agglomeration is done by breaking intermolecular bond between PVDF and cathode active materials as well as covalent bond within PVDF binders. The present work demonstrates a non-chemical method for liberating individual components from cathode composites for the direct recycling of LIBs.
With the rapid growth of the volume of spent Li-ion batteries (LIBs), recycling of spent LIBs has attracted significant attention in recent years for future sustainability. In particular, there remains a great need for the development of a scalable and environment-friendly separation process to recycle valuable cathode active materials from spent LIBs and electrode scraps. In this work, froth flotation technique was adopted to separate cathode active materials from a mixture of cathode and anode materials. To evaluate whether the recovered cathode materials maintain their functional integrity after the developed separation process, a variety of electrochemical analyses have been conducted systematically. The present work demonstrated that froth flotation process with kerosene enhanced separability of mixed electrode materials and the recycled cathode materials almost preserved their original electrochemical reactivity. Cycle performance (up to 200 cycles) and rate capability (up to 1 C) of the recycled cathodes were comparable to those of a pristine cathode. However, the higher polarization observed in the recycled cathodes was identified as a key challenge, and it needs to be addressed further. This work provides valuable insights into further development of a scalable froth flotation-based recycling process which can be implemented in a direct recycling process.
The effects of pyrolysis on the composition of the battery cell materials as a function of treatment time and temperature were investigated. A waste of Li-ion batteries was pyrolysed in nitrogen atmosphere at 400˚, 500˚, 600˚, and 700˚C for 30, 60, and 90 minutes. Thermodynamic calculations for the carbothermic reduction of active materials LiCoO2, LiMn2O4, and LiNiO2 by graphite and gas products were performed and compared to the experimental data. NMC cathode material recovered from spent Li-ion batteries was also studied. The results indicate that the organic compounds and the graphite are oxidized by oxygen from the active material and provide the reductive atmosphere. Such removal of the organic components increases the purity of the metal bearing material. Reactions with C and CO(g) led to a reduction of metal oxides with Co, CoO, Ni, NiO, Mn, Mn3O4, Li2O, and Li2CO3 as the main products. The reduction reactions transformed the metal compounds in the untreated LiB black mass to more soluble chemical forms. It was concluded that the pyrolysis can be used as an effective tool for the battery waste pretreatment to increase the efficiency of the leaching in a hydrometallurgical processing of the black mass. The results obtained can help to optimize the parameters in the industrial processing already used for Li-ion batteries recycling, especially if followed by the hydrometallurgical treatment. Such optimization will decrease the energy demand and increase metal recovery rate and utilization of the by-products.
In this study, a novel process of mechanical crushing combined with a pyrolysis-enhanced flotation was developed to recover LiCoO2 and graphite from spent lithium-ion batteries, which lays the foundation for the subsequent metallurgical process. Pyrolysis technology was used to solve the problem of low flotation efficiency of electrode materials. The pyrolysis characteristics of the electrode materials were carefully analyzed, and based on the results, the effects of pyrolysis treatment on the surface micro-characteristics, surface element chemical states, and mineral phases of electrode materials were fully investigated to explore the pyrolysis flotation enhancement mechanism. Afterwards, flotation methods were utilized to separate LiCoO2 from graphite. Surface micro-characterization analysis showed that the residual organic binders and electrolytes were the main reason that resulted in a low flotation efficiency of electrode materials. The thermogravimetric analysis and pyrolysis products indicated that the organic binders and electrolyte can be removed at a pyrolysis temperature of 500 °C. X-ray powder diffractometer analysis demonstrated that the electrode particle mineral phases were not altered at a pyrolysis temperature of less than 550 °C. The optimum flotation behavior was presented at a pyrolysis temperature of 550 °C with heating rate of 10 °C/min and pyrolysis time of 15 min LiCoO2 grade is 94.72% with the recovery of 83.75% in this condition. Two stage pyrolysis-enhanced flotation processes can further upgrade the LiCoO2 grade to 98.00%. This research proposes a novel method to improve the flotation efficiency of electrode materials, and the relevant mechanism is explored, which provides an alternative recycling flowchart of spent lithium-ion batteries.
An environmental-friendly technology of pyrolysis-ultrasonic-assisted flotation for recovering graphite and LiCoO2 from spent Lithium-ion battery has been conducted in this paper. Surface properties and morphology of graphite and LiCoO2 derived from spent Lithium-ion battery were carefully studied and on this basis their pyrolysis characteristics were investigated by thermogravimetry gas chromatograph-mass spectroscopy. Advanced analysis techniques, scanning electron microscope, X-ray fluorescence spectrometer and X-ray photoelectron spectroscopy, were utilized to analyze the effect of pyrolysis and ultrasonic on the surface properties and morphology of graphite and LiCoO2. Flotation tests were conducted to evaluate the reinforcing effect of pyrolysis-ultrasonic on flotation behavior. Results show that organic binder and electrolyte is the main reason that graphite and LiCoO2 are hard to be separated by flotation, meanwhile, pyrolysis can effectively decompose organic binders at pyrolysis temperature of 500 °C and ultrasonic cleaning can effectively remove residual pyrolysis products. Pyrolysis-ultrasonic-assisted flotation can make the LiCoO2 grade improved from 67.25% to 93.89% with the recovery improving from 74.62% to 96.88%. This research work may provide an alternative process for the preparation of high purity LiCoO2 particles for the subsequent chemical metallurgy.
An ability to separate battery electrode materials while preserving functional integrity is essential to close the loop of material use in lithium-ion batteries. However, a low-energy and low-cost separation system that selectively recovers electrode materials has not yet been established. In this study, froth flotation experiments were carried out with a variety of new and spent lithium-ion batteries using kerosene as the collector. The products were characterized using thermogravimetric and chemical analysis. It was found that over 90% of anode materials were floated in froth layers, while 10–30% of cathode materials were floated. Thermogravimetric analysis showed that the presence of binders and conductive additives might be responsible for the partial floatability of the liberated cathode materials. Separability of mixed electrode materials was evaluated using a modified procedure based on release analysis. Results showed that the froth flotation process using kerosene as the collector produced a tailing product having cathode materials of higher purity than those obtained without kerosene. For spent lithium-ion batteries, a low purity of cathode materials in tailings might be improved by fine grinding, at which freshly liberated hydrophobic surfaces are exposed and consequently anode materials become floatable. The present result confirms that the froth flotation technique is a viable and versatile technique in producing high purity cathode materials from lithium-ion batteries.
In this paper, a mechanical separation and thermal treatment process is developed to recover valuable metals and graphite from the −0.25 mm crushed products of spent lithium-ion batteries (LiBs). Effect of key parameters for roasting such as the temperature and roasting time are investigated to determine the most efficient conditions for surface modification of the mixed electrode materials by roasting. The roasted mixed electrode materials are separated by flotation operation to recover the cathode material and anode materials respectively. The results show that most of the organic outer layer coated on the surface of the mixed electrode materials can be removed at the temperature of 450 °C for 15 min. After roasting treatment, the original wettability of LiCoO2 and graphite is regained. The −0.25 mm crushed products of spent LiBs can be separated into LiCoO2 concentrate and graphite concentrate by flotation process efficiently. The enrichment ratios of Co, Mn, Cu and Al are 1.35, 1.29, 1.25 and 1.19, their recovery rates are 97.66%, 93.66%, 90.14% and 86.29%, respectively. This process proposed for the recovery of valuable materials is simple and of high efficient for the spent lithium-ion batteries recycling industry.
Due to the limitation of secondary pollution and high equipment investment, the industrial-scale recycling technology for electrode materials from spent lithium-ion batteries (LIBs) needs urgent breakthrough. In this paper, a physical recycling method, grinding flotation, is creatively proposed for the separation and recovery of LiCoO2 and graphite from spent LIBs. According to the exploratory experiments, if the mixed electrode materials is ground in the hardgrove machine for 5 min before reverse flotation, the concentrate grade of LiCoO2 sinks and graphite floats can reach 97.13% and 73.56%, respectively. Moreover, with the help of advanced analytical technologies, the surface morphology, elemental chemical states and element distribution on the very surface of electrode particles before and after grinding were systematically analyzed to reveal the mechanism of dry surface modification. Results indicate that the mechanical grinding destroys the lamellar structure of graphite, exposing massive newborn hydrophobic surfaces. Meanwhile, the abrasion of organic film coating the LiCoO2 particles causes its original hydrophilic surface partially regained. Hence, the great wettability difference between LiCoO2 and graphite contributes to an excellent flotation separation. This grinding flotation method is a promising separation method without any toxic emissions or introducing other impurities in industrial application.
The large-batch application of lithium ion batteries leads to the mass production of spent batteries. So the enhancement of disposal ability of spent lithium ion batteries is becoming very urgent. This study proposes an integrated process to handle bulk spent lithium manganese (LiMn2O4) batteries to in situ recycle high value-added products without any additives. By mechanical separation, the mixed electrode materials mainly including binder, graphite and LiMn2O4 are firstly obtained from spent batteries. Then, the reaction characteristics for the oxygen-free roasting of mixed electrode materials are analyzed. And the results show that mixed electrode materials can be in situ converted into manganese oxide (MnO) and lithium carbonate (Li2CO3) at 1073 K for 45 min. In this process, the binder is evaporated and decomposed into gaseous products which can be collected to avoid disposal cost. Finally, 91.30% of Li resource as Li2CO3 is leached from roasted powders by water and then high value-added Li2CO3 crystals are further gained by evaporating the filter liquid. The filter residues are burned in air to remove the graphite and the final residues as manganous-manganic oxide (Mn3O4) is obtained.
Fenton modified flotation is one of the effective ways to separate and recycle the electrode materials, LiCoO2 and graphite, from spent lithium-ion batteries (LiBs). However, a satisfactory LiCoO2 grade of flotation concentrate still could not be achieved after the Fenton modification. Comparison of its flotation results with the direct flotation and roasting modified flotation indicates the concentrate grade of LiCoO2 after Fenton treatment only increased by 5%, reaching 60%, while that of the roasting flotation could be up to 90%. Analyses of surface morphology and chemical composition indicate that the newborn surface of the electrode particles are wrapped with an inorganic compound layer composed of Fe(OH)3, which is the secondary product of semi-solid phase Fenton. The inorganic film results in a similar hydrophobicity and finally leads to the poor flotation results. Deducing from the reaction mechanism of Fenton, the enhancement of alkaline environment is a main reason for the precipitation of Fe3 + on the surface of particles. Therefore, an appropriate amount of hydrochloric acid (HCl) was added to react with precipitation, and the final concentrate grade reached 75%.
Extensive use of LiFePO4 batteries will afford a lot of spent LiFePO4 batteries, which cannot be recycled properly by using traditional processes at present. If these spent LiFePO4 batteries are thrown away without recycling properly, it is not only a severe waste of valuable resources, but also leads to serious environmental pollution. In this paper, a completely green recycling process and a small scale model line are developed to recycle cathode powders from spent LiFePO4 batteries for the first time. Parts of LiFePO4 host particles in spent LiFePO4 batteries decompose to FePO4, Fe2O3, P2O5 and Li3PO4 after numerous charge–discharge cycles, resulting in poor electrochemical performance of freshly recycled cathode powders for Li-ion batteries. To repair decomposed LiFePO4 host particles, recycled cathode powders are heat-treated at different temperatures. After heat-treatment at high temperatures, especially at 650 °C, cathode powders are effectively recycled and can be reused for Li-ion batteries.
Methods of wet and dry crushing are adopted to experiment on spent lithium-ion batteries in this investigation. Particle size distribution is analyzed using the wet and dry screening respectively and fine crushed products are characterized by XRD, SEM and EDX. A comprehensive comparison of the characteristics between the two crushing methods indicates that the wet crushing results in an enrichment of each component in spent lithium-ion batteries to fine fractions because of the scouring action of water flow, which makes the fine products complicated and lost; while the dry crushing method can bring the selective crushing characteristics of spent lithium-ion batteries into full play, and in this case, lithium cobalt oxide and graphite electrode materials can be liberated from aluminum foil and copper foil without the overcrushing of the other components in spent lithium-ion batteries. Thus, the purity and dispersion of electrode materials can be improved to create favorable conditions for subsequent purification and regeneration.
Increasing use of recycle water in flotation often has negative effects on recovery and grade. These have been traced to the accumulation of dissolved compounds, inorganic and organic, which alter the chemistry of the system. Some examples from industrial experience with complex sulphide and non-sulphide ores are discussed. In complex sulphide systems the loss in selectivity and recovery can be traced to one or a combination of the following factors: residual xanthates and their oxidation products dixanthogens which adsorb unselectively on most sulphides; residual sulphides which cause undesirable depression; metallic ions like Cu++, Fe++, Pb++ which cause inadvertant activation; and alkaline earth metal ions which may activate the nonsulphide gangue. The adverse effect observed in nonsulphide systems have been discussed in terms of: residual flotation agents including carboxylate collectors, alkyl sulphates and amines all of which reduce selectivity by their relatively unselective adsorption characteristics; and Ca++ and Mg++ ions which increase the positive surface charge of the minerals and affect the action of flotation agents functioning by electrostatic mechanism. A number of wastewater treatment techniques which may be applicable to recycle water in flotation are discussed. These include physical adsorption methods using active carbon, coal or bentonite clay or mineral slimes, biological oxidation of organics, removal of ionic species by ion exchange resins, and relatively new techniques like reverse osmosis and atmospheric freezing. Potential applications of each of the techniques are discussed.
Water shortages have a direct impact on the life of many mining and mineral processing operations. Therefore, a good understanding of the effects of water quality on flotation performance is essential. In this study, effects of dissolved ions (both anions and cations) were investigated on the flotation performance of a Cu-Zn complex sulfide ore from Çayeli Bakır İşletmeleri A.Ş. (CBI) (Turkey) by means of batch flotation tests. The results of the flotation tests revealed that accumulation of dissolved metal ions and sulfide ions, mainly in the form of SO42− and S2O32–, changed both the froth stability and surface chemistry of the sulfide minerals. The froth stability and hence the recovery by entrainment, increased in conjunction with the dissolved ion concentration in water. The presence of dissolved metal ions, such as Cu2+ and Pb2+, also increased the flotation rate and recovery of sphalerite. In the case of pyrite, the activation by dissolved metal ions was observed for moderately contaminated recycled water samples. High concentrations of sulfide ions however, counteracted the activation effect and reduced the recovery of pyrite by true flotation.
Lithium cobalt oxide from a wasted lithium ion secondary battery (LIB) is recovered by means of flotation. At first, the wasted LIB was crushed by vertical cutting mill and classified by air table and vibration screen. Referring to the crushing and separating results, wasted LIB is represented by light materials (organic separator of anode and cathode of battery), metallic materials (aluminum & copper foil, aluminum case etc.) and electrode materials (mixture of lithium cobalt oxide (LiCoO2) and graphite).Electrode materials were thermally treated in a muffle furnace at 773K, followed by flotation to separate LiCoO2 and graphite. The fact that the surface of particles was changed from hydrophobic to hydrophilic due to the removal of binder from the surface at 773K.Considering the results, 92% LiCoO2 was recovered from electrode materials, whereas the purity was higher than 93%. The optimum conditions of flotation process were as follows: 0.2 kg/t kerosene as a collector, 0.14 kg/t MIBC as a frother and 10% pulp density.The experimental results suggested that this process by using mineral processing technology, such as crushing, screening, flotation, etc., is feasible to recover LiCoO2 from the wasted LIB representing a new recycling technique.
A system was investigated in which a swarm of air bubbles was dispersed in aqueous electrolyte solutions. the salts used were: NaCl, NaBr, NaI, Na2SO4, Na3PO4 LiCl, MgCl2, MgSO4, CaCl2, AlCl3 and Al2(SO43. The effects of the salts on the interfacial area of dispersion and on the oxygen transfer coefficient were investigated at various salt concentrations. The results showed a definite dependence of the surface area of dispersion on the valence of the ionic species and salt concentrations. A very satisfactory correlation was obtained for all the salts with the use of ionic strength as the correlating parameter. The mechanism of the coalescence-preventing action of the salts was discussed and explained on the basis of ion-water interactions. The oxygen mass transfer coefficient was found to be only slightly dependent on the presence of electrolytes in the range of concentrations used in this work. The importance and possible practical application of the results were briefly discussed.
Flotation of coal generally exhibits a maximum around neutral pH. This maximum, despite the marked mineralogical heterogeneity, has been attributed to the isoelectric point of the coal in this pH region. The results obtained in this study demonstrate the important role of multivariant ions in determining the pH dependence of flotation. Ca, Fe, and A electrolytes are found to depress coal in the pH region of metal hydroxide precipitation. Adsorption tests as a function of pH show coal to adsorb the multivalent ions in a manner similar to oxides. The data obtained here are examined in terms of possible surface and bulk precipitation of metal hydroxide species on coal surfaces.
Measurement of bubble size distributions in bubble column by a photoelectric probe showed that both electrolyte and organic solutes affect coalescence behaviour of aqueous solutions drastically within a narrow concentration range, changing from quick coalescence as in pure water to coalescence restraining. Besides the electrolytes NACl, Na2SO4, Al2(SO4)3, NaOH, organic compounds from homologous series (n-alcohols, diols, ketones, carboxylic acids), detergents, saccharose, and carboxymethylcellulose have been used as solutes. Rough relationships between concentrations for coalescence restraining and molecular properties can be given (ionic strength for electrolytes, number of C-atoms in homologous series of organic compounds), but no exact equations based on a theory of coalescence. For the n-alcohols (C1-C8), specific surface areas were calculated from experimental mean bubble diameters (Sauter diameters) and measured gas hold-up and compared to volumetric mass transfer coefficients from literature. Concentration dependence of the two types of data showed surprisingly good agreement with regard to the fact that the mass transfer data had been obtained in a gas-liquid contacting device (stirred vessel) quite different to the reactor used in this work (bubble column).
Major recent advances: Recent advances that contribute to our understanding of specific-ion effects in bubble coalescence include new theoretical and simulation efforts to determine the arrangement of ions at interfaces and a clearer recognition that specific-ion effects in bubble coalescence are related to many other phenomena that exhibit ion specificity.
Spent lithium-ion batteries contain lots of strategic resources such as cobalt and lithium together with other hazardous materials, which are considered as an attractive secondary resource and environmental contaminant. In this work, a novel process involving vacuum pyrolysis and hydrometallurgical technique was developed for the combined recovery of cobalt and lithium from spent lithium-ion batteries. The results of vacuum pyrolysis of cathode material showed that the cathode powder composing of LiCoO(2) and CoO peeled completely from aluminum foils under the following experimental conditions: temperature of 600°C, vacuum evaporation time of 30 min, and residual gas pressure of 1.0 kPa. Over 99% of cobalt and lithium could be recovered from peeled cobalt lithium oxides with 2M sulfuric acid leaching solution at 80°C and solid/liquid ratio of 50 g L(-1) for 60 min. This technology offers an efficient way to recycle valuable materials from spent lithium-ion batteries, and it is feasible to scale up and help to reduce the environmental pollution of spent lithium-ion batteries.
The effect of water chemistry on froth stability and surface chemistry of the flotation of a Cu-Zn sulfide ore
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New EU regulatory framework for batteries - Setting sustainability requirements
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A Vision for a Sustainable Battery Value Chain in 2030 - Unlocking the Full Potential to Power Sustainable Development and Climate Change Mitigation
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