Browsing by Author "Rinne, Tommi"
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- Esikäsittelyprosessit kierrätettyjen litiumioniakkujen elektrodimateriaalien vaahdotustalteenoton tehostamisessa
Kemiantekniikan korkeakoulu | Bachelor's thesis(2020-01-14) He, Songwen - Innovations in Li-ion Battery Recycling: Advanced Physical Separation, Characterization, and Industrial Process Integration
School of Chemical Technology | Doctoral dissertation (article-based)(2024) Rinne, TommiThe exponential growth in the electric vehicle market and the rising demand for sustainable energy storage solutions have resulted in a significant increase in the production rates of lithium-ion batteries (LIBs). Consequently, the demand for critical raw materials needed for LIB manufacturing (e.g., Co, Ni, Cu, graphite, and Li) is projected to increase rapidly in the coming years. Current industrial-scale recycling technologies, namely pyrometallurgy and hydrometallurgy, face limitations in processing end-of-life LIBs and recovering valuables from their active component mixtures (a.k.a., black mass). To overcome these limitations, this Thesis investigated the potential of froth flotation as a separation process for direct recycling of LIBs, an approach aimed at preserving the structural and chemical integrity of the anode and cathode active minerals (CAMs). The research comprised multiple campaigns ranging from fundamental understanding of flotation mechanisms to the integration of flotation in industrial processes. Firstly, a novel tomographybased methodology was developed to characterize flotation froths, thus providing insights into the extraction mechanisms of solid particles. A previously overlooked phenomenon was uncovered, where binder-free lithium cobalt oxide (LCO) particles were observed to be hydrophobized by a common oily collector – indicating a lack of collector selectivity. Another campaign focused on flocculation of CAMs, specifically demonstrating the potential for selectively flocculating LCO particles in mixtures with graphite. Building on these insights, a combined approach of selective flocculation and froth flotation was studied, showing promise in improving the selectivity of graphite separation from black mass through a CAM-selective flocculation pretreatment. Lastly, the integration of LIB recycling into existing industrial slag cleaning processes was studied. It was demonstrated that, in the presence of binder polymers, flotation can effectively separate an industrial black mass into a froth concentrate rich in active minerals and an underflow concentrate comprising current collector metals. Furthermore, the refining of these concentrates was successfully integrated with industrial Ni slag cleaning and Cu slag cleaning processes, revealing synergistic benefits. The integrated processes were found to be chemically self-sustaining, requiring no additional reductants for refining valuable metals Cu, Co, Ni, and Fe, although loss of Li, Al, and Mn to the slag phase was observed. In summary, this thesis presents a comprehensive investigation into advanced characterization and physical separation techniques for LIB recycling, with perspectives on industrial process integration. The findings contribute to the development of more efficient, cost-effective, and environmentally sustainable recycling methods. The studied methods are expected to address existing concerns associated with the growing demand for critical battery materials. - Integrating flotation and pyrometallurgy for recovering graphite and valuable metals from battery scrap
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2020-05) Ruismäki, Ronja; Rinne, Tommi; Dańczak, Anna; Taskinen, Pekka; Serna-Guerrero, Rodrigo; Jokilaakso, AriSince the current volumes of collected end-of-life lithium ion batteries (LIBs) are low, one option to increase the feasibility of their recycling is to feed them to existing metals production processes. This work presents a novel approach to integrate froth flotation as a mechanical treatment to optimize the recovery of valuable metals from LIB scrap and minimize their loss in the nickel slag cleaning process. Additionally, the conventional reducing agent in slag cleaning, namely coke, is replaced with graphite contained in the LIB waste flotation products. Using proper conditioning procedures, froth flotation was able to recover up to 81.3% Co in active materials from a Cu-Al rich feed stream. A selected froth product was used as feed for nickel slag cleaning process, and the recovery of metals from a slag (80%)–froth fraction (20%) mixture was investigated in an inert atmosphere at 1350 °C and 1400 °C at varying reduction times. The experimental conditions in combination with the graphite allowed for a very rapid reduction. After 5 min reduction time, the valuable metals Co, Ni, and Cu were found to be distributed to the iron rich metal alloy, while the remaining fraction of Mn and Al present in the froth fraction was deported in the slag. - Leaching strategies for the recovery of Co, Ni, Cu and Zn from historical tailings
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2024-10) Alajoki, Julia; Karppinen, Anssi; Rinne, Tommi; Serna-Guerrero, Rodrigo; Lundström, MariEnergy 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 (O2, 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 °C, 5 min). In water leaching, the system stabilized inherently to pH=3.7 and the redox potential to Eh < 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. - On the Colloidal Behavior of Cellulose Nanocrystals as a Hydrophobization Reagent for Mineral Particles
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2021-02-23) Hartmann, Robert; Rinne, Tommi; Serna-Guerrero, RodrigoIn the search for more sustainable alternatives to the chemical reagents currently used in froth flotation, the present work offers further insights into the behavior of functionalized cellulose nanocrystals as mineral hydrophobization agents. The study corroborates that hexylamine cellulose nanocrystals (HACs) are an efficient collector for the flotation of quartz and also identifies some particular characteristics as a result of their colloidal nature, as opposed to the water-soluble reagents conventionally used. To investigate the individual and collective effects of the frother and HACs on the attachment of particles and air bubbles, an automated contact timer apparatus was used. This induction timer measures particle-bubble attachment probabilities (Patt) without the influence of macroscopic factors present in typical flotation experiments. This allowed the study of the combined influence of nanocellulose and frother concentration on Patt for the first time. While HACs readily adsorb on quartz modifying its wettability, the presence of a frother leads to a drastic reduction in Patt up to 70%. The improved recovery of quartz in flotation cells might thus be attributed to froth stabilization by HACs, perhaps acting as a Pickering foam stabilizer. Among the main findings, a tendency of HACs to form mineral agglomerates was identified and further explained using the extended DLVO theory in combination with measured adsorption rates in a quartz crystal microbalance. Therefore, this study distinguishes for the first time the antagonistic effect of frothers on Patt and their synergies with HACs on the stabilization of orthokinetic froths through the hydrophobization mechanism unlike those of typical water-soluble collectors. - Panos–tuotos-matriisi elinkaariarvioinnin työkaluna
Kemiantekniikan korkeakoulu | Bachelor's thesis(2016-05-08) Rinne, Tommi - Quantifying the degree of selectivity in a Flocculation-Flotation process of LiCoO2 and graphite using scanning electron microscopy and image processing analysis
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2024-04) Rinne, Tommi; Saeed, Mohazzam; Serna-Guerrero, RodrigoThis 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 flocculation-flotation processes. - Recovering value from end-of-life batteries by integrating froth flotation and pyrometallurgical copper-slag cleaning
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2022-01) Rinne, Tommi; Klemettinen, Anna; Klemettinen, Lassi; Ruismäki, Ronja; O’Brien, Hugh; Jokilaakso, Ari; Serna-Guerrero, RodrigoIn this study, industrial lithium-ion battery (LIB) waste was treated by a froth flotation process, which allowed selective separation of electrode particles from metallic-rich fractions containing Cu and Al. In the flotation experiments, recovery rates of ~80 and 98.8% for the cathode active elements (Co, Ni, Mn) and graphite were achieved, respectively. The recovered metals from the flotation fraction were subsequently used in high-temperature Cu-slag reduction. In this manner, the possibility of using metallothermic reduction for Cu-slag reduction using Al-wires from LIB waste as the main reductant was studied. The behavior of valuable (Cu, Ni, Co, Li) and hazardous metals (Zn, As, Sb, Pb), as a function of time as well as the influence of Cu-slag-to-spent battery (SB) ratio, were investigated. The results showcase a suitable process to recover copper from spent batteries and industrial Cu-slag. Cu-concentration decreased to approximately 0.3 wt.% after 60 min reduction time in all samples where Cu/Al-rich LIB waste fraction was added. It was also showed that aluminothermic reduction is effective for removing hazardous metals from the slag. The proposed process is also capable of recovering Cu, Co, and Ni from both Cu-slag and LIB waste, resulting in a secondary Cu slag that can be used in various applications. - Reprocessing and leaching of valuable metals from weathered flotation tailings
Kemian tekniikan korkeakoulu | Master's thesis(2024-01-23) Alajoki, JuliaTo mitigate the global warming a clean energy transition is needed. This transition relies highly on non-renewable minerals and metals. In order to ensure the supply of mineral raw materials, metals recovery from alternative raw material resources needs to be studied. The mining industry produces vast amounts of waste (waste rock and tailings) as a by-product and in 2018 over 75% of all waste in Finland originated from mining operations. The waste consists of gangue, minerals with no commercial value, as well as small traces of valuables. In this thesis weathered flotation tailings are investigated as one potential stream to produce Co and Ni as well as Cu and Zn, elements necessary for clean energy applications. The studied tailing originates from Keretti tailings area (Outokumpu) and has been weathering since 1954. The valuables were expected to occur in sulfide minerals and Co, Ni, Cu, Zn, Fe, and S content in the raw material are 0.081%, 0.055%, 0.17%, 0.15%, 8.21%, and 5.67%, respectively. The purpose of the thesis was to evaluate the suitability of the raw material for concentrate production and hydrometallurgical processing. According to the results, it is possible to produce concentrate via froth flotation. However, more flotation stages including scavenger stage are needed to increase the recovery of valuables and decrease the sulfur content (2.6%) in the tailing. The recovery of Co, Ni, Cu, and Zn by froth flotation to the rougher concentrate was 73%, 54%, 68%, and 76% while their grades were 0.20%, 0.09%, 0.52%, and 0.50%, respectively. For the cleaner concentrate the recoveries and grades were 60% and 0.27% for Co, 39% and 0.11% for Ni, 54% and 0.66% for Cu, and 65% and 0.69% for Zn. Some amount of Co, Ni, and Fe were found to leach into the solution during flotation. The leaching results showed that 21% of Co and 38% of Ni were extracted into the solution by water leaching of the weathered tailing for 5 minutes. The extraction of Fe into PLS was low in water leaching. The extraction of Co increased slightly (5%-units) by acid leaching under varying oxidizing conditions and the highest extraction of Ni (60%) was achieved in cupric chloride leaching. The highest total valuable metals recovery of the flotation-leaching process was achieved in ferric sulfate leaching. More studies are needed to evaluate the suitability of the raw material for hydrometallurgical metals refining processing. - A study on the correlation of mineralogical properties of Li-ion battery waste and the efficiency of separation processes
Kemian tekniikan korkeakoulu | Master's thesis(2022-10-18) García Salinas, Hillary MichelleIt is now well established that the presence of organic compounds (PVDF binder and electrolyte) on the surface of cathode and anode materials impair their separation by flotation as their wettability difference is reduced. Aiming to remove these organic substances and liberate the electrode particles to get a better flotation efficiency, two conditioning methods were applied to black mass before flotation: mechanical attrition, i.e., milling for 1 min and 40 min, and thermal degradation i.e., pyrolysis at 500°C and 600°C. The evolution of morphology, composition, and liberation degree of black mass samples after pyrolysis and milling were investigated by SEM-EDS and TGA-MS. The EDS results demonstrated that pyrolysis decreased the F content coming from the PVDF binder from 33%w to 5–6%w, whereas milling only reduced it to 10–20%w. The SEM micrographs also display fewer presence of aggregates of cathode particles in pyrolyzed samples compared to milling samples. Other features observed by SEM that might impact black mass flotation are also discussed. Additionally, by TGA-MS the degradation stage corresponding to organic compounds revealed the existence of more organics and impurities in samples treated by milling (5–6%w) than in the pyrolyzed samples (2–3%w) demonstrating that pyrolysis achieves a better liberation in black mass samples prior to flotation. - A Study on the Effect of Particle Size on Li-Ion Battery Recycling via Flotation and Perspectives on Selective Flocculation
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2023-01-17) Rinne, Tommi; Araya-Gómez, Natalia; Serna-Guerrero, RodrigoThe 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. - Towards Integration of Ni-Slag Cleaning Process and Lithium-Ion Battery Recycling for an Efficient Recovery of Valuable Metals
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2024-10) Klemettinen, Anna; Klemettinen, Lassi; Rinne, Tommi; O'Brien, Hugh; Jokilaakso, Ari; Serna-Guerrero, RodrigoSpent 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. - The unexpected stability of froth structures formed with battery materials allow their characterization with x-ray computed tomography
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2025-02) Rinne, Tommi; Kuva, Jukka; Serna-Guerrero, RodrigoAs 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 utilization of hydroxypropyl methylcellulose as a flotation frother for chalcopyrite-containing ores
Kemian tekniikan korkeakoulu | Master's thesis(2018-11-06) Rinne, TommiFroth flotation is a widely applied mineral separation technique, in which minerals are enriched in a complex three-phase system (froth) that comprises of air-, liquid-, and solid phases. In the flotation process, a variety of reagents are needed to control the chemical environment of the process, and to provide the basis for the separation to happen. Frothers, which are flotation chemicals used to control the properties of air bubbles, are an example of such reagents. Recently, efforts have been made to improve the environmental performance of flotation by replacing some of the industrially applied hazardous reagents by more sustainable alternatives. In this master’s thesis, a sustainable cellulose-based frother (hydroxypropyl methylcellulose, HPMC) was studied and compared to a commercially available frother. The aim of this thesis was to understand the theory of flotation, the theory of macromolecular frothers, and the role of frothers in the flotation process in general. Furthermore, in the experimental section, an effort was made to optimize the flotation parameters for chalcopyrite separation from a pyrite-rich Cu-Zn ore, utilizing HPMC as a frother. A total of 53 experiments were conducted, studying two distinctive types of HPMC both singularly, and in mixtures with the commercial frother. Furthermore, reference experiments were conducted utilizing the commercial frother only. HPMC was found to produce very stable froths at concentrations exceeding 30ppm, and the kinetics of the HPMC-based separation were observed to be superior compared to the commercial frother. Furthermore, on its own HPMC produced very high recoveries of the valuables but failed to separate them selectively. However, when applied in mixtures with the commercial frother, the selectivity of the process could be improved, while the high recovery values were maintained (also with HPMC concentration well-below the 30ppm threshold point). In the experiments, the best separation efficiency obtained with a mixture was 69.51%, whereas the commercial frother performed slightly better at 74.67%. These values were not yet on an industrially acceptable level (due to poor pyrite depression) but they were still comparable with one another. Although further research is needed, based on these results it can be stated that HPMC seems to be a potential alternative, when it comes to improving the environmental performance of flotation. - Worth from waste: Utilizing a graphite‐rich fraction from spent lithium‐ion batteries as alternative reductant in nickel slag cleaning
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2021-07-19) Danczak, Anna; Ruismäki, Ronja; Rinne, Tommi; Klemettinen, Lassi; O’Brien, Hugh; Taskinen, Pekka; Jokilaakso, Ari; Serna‐Guerrero, RodrigoOne possible way of recovering metals from spent lithium‐ion batteries is to integrate the recycling with already existing metallurgical processes. This study continues our effort on integrating froth flotation and nickel‐slag cleaning process for metal recovery from spent batteries (SBs), using anodic graphite as the main reductant. The SBs used in this study was a froth fraction from flotation of industrially prepared black mass. The effect of different ratios of Ni‐slag to SBs on the time‐dependent phase formation and metal behavior was investigated. The possible influence of graphite and sulfur contents in the system on the metal alloy/matte formation was described. The trace element (Co, Cu, Ni, and Mn) concentrations in the slag were analyzed using the laser ablation-inductively coupled plasma‐mass spectrometry (LA‐ICP‐MS) technique. The distribution coefficients of cobalt and nickel between the metallic or sulfidic phase (metal alloy/matte) and the coexisting slag increased with the increasing amount of SBs in the starting mixture. However, with the increasing concentrations of graphite in the starting mixture (from 0.99 wt.% to 3.97 wt.%), the Fe concentration in both metal alloy and matte also increased (from 29 wt.% to 68 wt.% and from 7 wt.% to 49 wt.%, respectively), which may be challenging if further hydrometallurgical treatment is expected. Therefore, the composition of metal alloy/matte must be adjusted depending on the further steps for metal recovery.