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The massive spent lithium-ion batteries (LIBs) need to be recycled due to their increasing decommission in recent years. This paper aims to propose an effective process that uses self-supplied reductant roasting and acid leaching to recover Lithium, Nickle, Cobalt and Manganese from spent LIBs. In the absence of external carbon resources, the waste membrane from spent LIBs was used as the reductant in the self-supplied reductant roasting. A thermodynamic analysis was conducted to judge the possible reduction reaction between the cathode material and waste membrane. Then, the effects of roasting temperature, roasting time and membrane dosage on the crystal structure and phase transformation of roasting products were investigated and optimized. After the roasting process, the valence state of metals in the cathode material decreased and the structure became loose and porous. Moreover, the layer structure of the cathode material was transformed into groups of Li

To improve the adhesion between cathode materials and current collector, and increase the electronic conductivity among electroactive substances, a certain proportion of conductive agents (acetylene black) and agglomerant (PVDF) are usually added in the battery manufacturing process. However, these conductive agents have negative effects on the recovery of cathode materials by pyrolysis or calcination. Recognizing this issue, a method based on the concept of "treating spent with spent" was developed in this paper. Organic matters contained in cathode active materials functioned as the reduction reagents, which can reduce the valence state of transition metals, resulting in the breakdown of the strong chemical bond and the stable layered structure of cathode materials. In this study, the thermal reduction effect of different organic components on cathode active materials was analyzed respectively to evaluate the reduction function of each component. XRD, XPS and ICP-MS were used to compare and analyze changes of phase, element compound state and ion leaching efficiencies of different cathode materials before and after thermal reduction under different amounts of reducing agents. The results show that both PVDF and acetylene black reduced the high-valent metals to low-valent oxides or elemental substances, demonstrating their thermal reduction capabilities. Comparisons of the XRD, XPS analysis and ion leaching results of thermal reduced products suggest that acetylene black has a stronger thermal reduction ability than that of PVDF. The results also show that the reduction of the high nickel cathode material (NCM811) is easier than that of the low nickel cathode material (NCM111).

Liberation and reduction of cathode material are the necessary procedures for improving the recycling efficiency of cathode material derived from spent lithium-ion batteries. In this research work, a pyrolysis technology was utilized to remove the organic binder and enhance liberation of electrode materials. At the same time, pyrolysis treatment can facilitate the thermal-reduction of Co3+ in LiCoO2 to Co2+ with surface organics, which lays a foundation for the subsequent reductant-free acid leaching. Results indicate that the crystal structure of pure LiCoO2 is not changed at a pyrolysis temperature of 600 °C, but LiCoO2 transforms to CoO, Li2CO3, LiF, and Li2O under the reduction action of HF, pyrolytic carbon, and additive carbon black. Water-impact crushing is synchronized with water-leaching to separate electrode materials from aluminum foil and recover Li element. Afterwards, reductant-free acid leaching technology can be utilized to recycle Li and Co from spent LiCoO2 batteries. Recovery efficiency of Li element in water-leaching process was up to 92.17% while the remaining 7.83% of Li and all Co elements were recovered during reductant-free acid leaching process. Based on the foundation analysis, the green chemical process for recovering valuable metals from spent lithium-ion batteries was proposed.

Organics retained in electrode materials decrease the liberation and flotation efficiency of electrode materials. The pyrolysis-assisted sustainable process was used to remove the organic binder an...

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 Li

The present work focuses on simultaneous recycling of Li and Co from crushed products of mixed electrode materials using mixed organic acids, in which benzenesulfonic acid and formic acid were cooperatively used as the leaching reagents. Results show that the optimal leaching efficiency of 97% Co and 99% Li were obtained under the conditions of 1.3 mol/L benzenesulfonic acid, 1.5 mol/L formic acid, a solid to liquid (S/L) ratio of 30 g/L, and 40 min reaction time at 50 °C. Meanwhile, the leaching of Li and Co fits well to logarithmic rate model with apparent activation energy of 32.7 and 47.0 kJ/mol in this given leaching system, respectively. Besides, cobalt was directly recovered from the leach liquor as pure cobalt benzene sulfonic with the recovery efficiency of 99%, and lithium can be entirely precipitated by adding phosphoric acid. Further, the reaction mechanism involves the leaching-hydrating-complexing model of LiCoO2 particles was proposed based on the dissolution behavior of metals and then verified by morphological and phase characterization (i.e. FT-IR, XRD and SEM-EDS) of the recycling product. The whole process is found to be effective and sustainable for recovery of Li, Co and graphite from mixed industrial crushing product of spent LIBs.

Electrostatic effects are commonly found in gas-solid fluidized beds. With an electrical field applied in a gas-solid fluidized bed, the charged particles there would be separated according to the opposite charge polarity. A charge-to-mass ratio test showed that quartz can easily be given a negative charge when tribo-charging with coal. A binary particle mixture was employed to explore the enrichment effect in an electrical-field fluidized bed unit. The results showed that the mass fraction of quartz in the products decrease gradually from negative plate to positive plate. The increase of fluidization time, plate voltage and gas velocity, along with low bed height, were beneficial to the improvement of the enrichment effect. The mass fraction of quartz close to the positive plate was >40%, while that of negative was around 10%. This work demonstrates the possibility of separating fine coal using a fluidized bed with applied electrical field.

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.

The nonmetallic fractions (NMFs) from waste printed circuit boards mainly comprise organic materials (OMs) and inorganic materials, taking up a large proportion of E-waste. The NMFs can be used as fillers for composite materials by decreasing the content of inorganic materials. In this study, a novel conical surface triboelectric separator based on the tribocharge difference of organics and inorganics was used to concentrate OM and remove inorganics to improve the usability of NMFs. The X-ray fluorescence (XRF) analysis showed that the content of OM in the raw samples was up to 73.03%, and Si, Al, Br, and Ca were the main inorganic elements in the NMFs. The experimental results demonstrated that the organic particles were negatively charged while the inorganic particles were positively charged in the process of particle friction and collision. The effects of feed rate, rotation speed, and voltage on the triboelectric separation of NMFs were investigated, and the optimum separation was achieved at 12.96 kg/h feed rate, 500 r/min rotation speed and 50 kV voltage. The OM content in the positive plate product increased to 85.12% with a yield of 28.81%, while that in the negative plate product decreased to 59.22% with a yield of 36.45%. The test results demonstrated that the novel conical surface triboelectric separator can effectively recycle OM from the NMFs and facilitate the subsequent reutilization of NMFs.

Recycling of valuable metals from spent lithium ion batteries (LIBs) is of great significance considering the conservation of metal resources and the alleviation of potential hazardous effects on environment. Thus, the present work focuses on enhancing the efficiency of leaching process for the recovery of cobalt and lithium from the cathode active materials of spent LIBs. In this study, benzenesulfonic acid (C6H5SO3H) with a reducing agent hydrogen peroxide (H2O2) was innovatively used as leaching reagents, and the operating variables were optimized to obtain higher leaching efficiencies. Results show the optimized leaching recovery of 99.58% Li and 96.53% Co was obtained under the conditions of 0.75 M benzenesulfonic acid, 3 vol% H2O2, a solid to liquid (S/L) ratio of 15 g/L, 500 rpm stirring speed, and 80 min leaching time at 90 °C. Moreover, a new kinetic model was introduced to describe the leaching kinetics of LiCoO2 from the cathode material. The apparent activation energies Ea for leaching of lithium and cobalt are 41.06 and 35.21 kJ/mol, respectively, indicating that the surface chemical reaction is the rate-controlling step during this leaching process. Further, the proposed recovery mechanism for spent cathode material was raised by analyzing the experimental results and characterizing the morphological and chemical state (i.e. SEM-EDS, XPS and XRD) of raw material and leaching residues. In comparison with the previous leaching process, this research was found to be efficient, low energy consumption, and environmental friendly.

Scrapers are important inner components in continuous fluidized beds in the state where they are most commonly used industry. Dynamic scrapers have significant effects on fluidization characteristics. A lab-scale continuous air dense medium fluidized bed (CADMFB) was designed, and the influences of operational parameters were studied. Moving scrapers lead to velocity gradients in the horizontal direction among magnetite particles in different bed heights, which assisted in loosening of the dense medium bed. Hence, bed pressure drop and minimum fluidization airflow rate were lower than those in beds with static scrapers. If the scraper velocity is kept constant, minimum fluidization airflow rate increases with increasing scraper distance. But the ratio of standard deviation to average bed pressure drop increases with the increase in the scraper distance, which indicates a decrease in bed stability. Minimum fluidization airflow rates also increased with increasing scraper velocities, but a fast scraper speed may also cause bed pressure fluctuations. Dynamic scrapers can inhibit the generation of big gas bubbles. Optimum scraper velocities for various scraper distances can be calculated by v > L g 0.6 π 0.2 1.43 Q 0.2 . Results indicate that 50 mm was the ideal scraper distance, and the optimum scraper velocity was about 0.35 m/s. Results also show that fluidization in boundary zones between dynamic scrapers and static sidewalls was worse than that of middle zones of CADMFB.

Nonmetallic fractions are essential byproducts of the physical-mechanical recycling process of waste printed circuit boards. Large amounts of metals remain in fine nonmetallic fractions because it is very hard for recycling metals from fine size fraction by traditional technologies. In this study, a vibrated gas-solid fluidized bed was utilized to recover residual metals from fine particles (−0.25 mm size) of nonmetallic fractions obtained from the corona electrostatic separation process. The basic mineralogical characteristics and properties of nonmetallic fractions with a size of −0.25 mm indicated that a considerable amount of clavate glass fibers existed in these nonmetallic fractions. The content of residual metals in the −0.25 mm nonmetallic fractions was up to 19.84 wt%. The major metallic elements found in the nonmetallic fractions were Fe, Cu, Pb, and Sn. The results indicated that removing glass fibers from nonmetallic fractions by triboelectric separation can strengthen the gravity-segregation process between heavy and light particles in fine nonmetallic fractions, resulting in improved metal recovery from 76.39% to 81.41%. Based on this research, an industrial flowsheet for the recovery of metals from fine WPCBs is proposed.

The efficient recycling of spent anode material (SAM) from spent lithium-ion batteries (LIBs) is generally critical in terms of electronic waste recyclingas well as increasing resource shortage and environmental problems. This research reported a novel and green method to recycle lithium, copper foil, and graphite from SAM by water leaching treatment. The results indicated that 100% of graphite was exfoliated from the anode material and 92.82% leaching efficiency of lithium was obtained under the optimal conditions of 80 °C, 60 g/L, 300 rpm, and 60 min, respectively. This finding revealed that the SAM got a full liberation characteristic due to the removal of binder, which produced an ideal leaching lithium efficiency rivaling the acids’ performance. The mechanism of the liberation of SAM and lithium leaching is presented based on the analysis of results. The graphite was purified and recovered after water leaching treatment. Besides, lithium was recovered in the form of lithium carbonate (Li2CO3), and the copper foil was recovered in a sheet. This study endeavors to develop an economical and environmentally feasible plan to recycle graphite, copper, and lithium from SAM.

In recent years, the amount of spent lithium-ion batteries (LIBs) increase sharply due to the promotion of new energy vehicles and the limited service life. Recycling of spent LIBs has attracted much attention because of the serious environmental pollution and high economic value. Although some established techniques have been presented in spent LIBs recycling process, but most of them focus on cathode material recycling due to its high economic value. Therefore, preparation of high purity cathode material by a proper pretreating technology is an important procedure. In this paper, the technologies used in the pretreating process of spent LIBs are summarized systematically from three main points of discharging procedure, liberation, and separation. The collaborative application of multi-technologies is the key to realize efficient pretreating process, which can lay the foundation for the subsequent metallurgical process. In addition, an alternative pretreating flowchart of spent LIBs is proposed based on the multi-process collaboration. Pretreating procedures in this process are mainly based on the physical property difference, and they include "Discharging-Shredding-Crushing-Sieving-Separation".

Proper disposal of spent lithium-ion batteries is beneficial for the resource recycling and pollution elimination. Full liberation of electrode materials, including the liberation between electrode material and current collector (copper/aluminum foils) and the liberation among electrode material particles, is the pivotal precondition for improving the recovery efficiency of electrode materials. In this article, authors attempt to carry out a summary of current technologies used in the liberation of electrode materials derived from spent lithium-ion batteries. However, specialized studies about the liberation of electrode materials are insufficient at present. This research clearly shows that: (1) Organic binder must be removed so as to improve the liberation and metallurgy efficiency of electrode materials; (2) A collaboration of varied technologies is the necessary process to achieve high liberation efficiency between electrode materials and copper/aluminum foils; (3) Pyrolysis may be a recommended technology for removal of organic binder because part of pyrolysis products can be recovered. Finally, an alternative recycling flowchart of spent LIBs is proposed.

The strong hydrophilic properties of both sub-bituminous coal and kaolinite make it difficult to separate by direct flotation. In this paper, the removal of kaolinite from fine sub-bituminous coal ...

Spent lithium-ion batteries contain metals, LiCoO2, graphite and other substances that can cause environmental pollution in the case of random disposal. Thus recycling of spent lithium-ion batteries is important. In this study, components in spent lithium-ion batteries are fully dissociated by crushing and screening in the first step. LiCoO2 and graphite particles are enriched in −0.25 mm products. Density and particle size of LiCoO2 particles are larger than those of graphite based on the analysis of physical property. Subsequently, the separation effect is obtained by adjusting the rotating speed and water counter pressure of Falcon centrifuge as well as particle size. Composition of sorted products and optimal sorting conditions are determined by calculation of roasting test and scanning electron microscope. Optimum conditions are as follows: water counter pressure at 0.025 MPa, rotation frequency at 50.00 Hz. Best grade and recovery efficiency of LiCoO2 are 84.87% and 83.14%, respectively. The result also indicates when the particle size ranges between 0.045 mm and 0.09 mm, the sorting performance reaches the best effect.

In this study, pyrolysis was utilized to enhance the liberation of electrode particles in the recycling process of spent lithium-ion batteries. Pyrolysis characteristics of cathode and anode materials and the effects of pyrolysis on the liberation of electrode materials were fully investigated. Afterwards, scanning electron microscope coupled with an energy dispersive spectrometer and X-ray photoelectron spectroscopy were used to reveal the changes of mineralogical characteristics of electrode materials before and after pyrolysis. The results indicate that organic binder wrapped on electrode particles is the main reason that electrode materials are hard to liberate from foils and difficult to liberate each other. The optimum pyrolysis temperature of organic binders in electrode materials is 500 °C and the main pyrolysis products are fluorine-containing benzene and ester electrolyte. The liberation efficiency of cathode increases from 82.88% to 99.78% by pyrolysis, while that of anode increases from 88.08% to 99.60%. Meanwhile, adequate liberation of pyrolytic electrode materials requires a shorter period of time. Electrode materials from pyrolytic electrode are mainly concentrated in −0.045 mm size fraction, and they are up to 82.49% and 78.91% respectively for cathode and anode materials. 5106.

Liberation and reduction of cathode material are the necessary procedures for improving the recycling efficiency of cathode material derived from spent lithium-ion batteries. In this research work, a pyrolysis technology was utilized to remove the organic binder and enhance liberation of electrode materials. At the same time, pyrolysis treatment can facilitate the thermal-reduction of Co

Thermal decomposition was used to enrich indium tin oxide (ITO) from waste colour filter glass. The colour layer was destroyed through oxidation, and the ITO layer was separated from the glass substrate. With the increase in the temperature and time of thermal decomposition, the yield of ITO concentrate decreased, but the ITO recovery and enrichment ratio increased. Furthermore, the ITO could be effectively enriched at 600 °C and 8 min, where the yield, recovery and enrichment ratio of ITO were 0.06 %, 98 % and 1669, respectively. The particle size distribution of the ITO concentrate was mainly distributed in 0.1–1.3 and 2.6–42.0 μm, with cumulative percentages of 4.33 % and 95.55 %, respectively. Moreover, the crystal structure of recycled ITO was not changed. Substantial poisonous and harmful mixed flue gas are produced during thermal decomposition. After condensation and adsorption by activated carbon, the emission of mixed flue gas could be effectively controlled to avoid serious pollution to the atmospheric environment.

An environmentally-friendly technology of pyrolysis-ultrasonic-assisted flotation for recovering graphite and LiCoO2 from spent lithium-ion batteries has been evaluated in this paper. Surface prope...

Flotation is used to enrich indium tin oxide from the colour filter glass of waste liquid crystal display panels. Contact angle measurement and infrared spectroscopy analysis indicated that colour filter contained hydrophobic methyl groups and aromatic ring. Crushing experiment and backscatter imaging analysis revealed that the colour filter with indium tin oxide almost separated from the glass substrate with size fraction of −0.032 mm. The proportion of particles in the −0.032 mm fraction increased with increasing grinding time. A sufficient dissociation was found between the colour filter with indium tin oxide and the glass substrate, and the indium content in the fine size fraction also increased. Moreover, the indium content, indium tin oxide concentrate yield and indium tin oxide recovery increased with decreasing feed size. The indium content of the indium tin oxide concentrate reached 0.61%, the indium tin oxide recovery peaked at 85.21% and the enrichment ratio was 16.6 in particles with size below 0.025 mm. Furthermore, the indium content, indium tin oxide concentrate yield and indium tin oxide recovery increased with increasing grinding time. After 80 min of grinding, the indium tin oxide recovery peaked at 92.51%, the indium content of the indium tin oxide concentrate reached 0.60% and the enrichment ratio was 18.4.

Nonionic surfactants have been applied to improve the lignite floatability in the flotation process. In this paper, Inner Mongolia lignite was pretreated by three type surfactants, including sorbit...

Mixture breakage of particles in various sizes is common in industrial mills, and breakage behavior is influenced by size composition. But studies on particle breakage are conducted to narrowly sized samples. In this paper, tentative works are made to investigate interaction among super clean coal in mixture breakage from aspects of breakage rate, energy consumed characteristics and energy split factors. Experimental results demonstrate that breakage rate of coarse particles in mixture breakage increases if compared with that in single breakage. Particle size is modelled into classical breakage equation, and the modified model is successfully applied to mixture breakage. Energy split factor of component is determined based on the balance of specific energies of components in heterogeneous breakage and energy-size equation, and consumed energy (W) of component in multi-component grinding is calculated. Calculated energy split factors of components are all above one in various mixed conditions, so energy efficiency (value of product t10 at the same specific energy) decreases if compared with that of single breakage. Energy split analyses are also conducted for mixture breakage of middling coals, which illustrates that the method is robustness for energy-size reduction process influenced by associated minerals in coal.

Breakage behaviors and energy consumed characteristics of coal are directly influenced by properties, such as particle size, ash content or density. It is essential to model these effects and conduct quantitative evaluation. In this study, samples of 4 particle sizes × 4 ash contents were ground in a Hardgrove mill for 9 energy levels, respectively. Breakage rate of particles in the top size and t10 were determined and effects of coal properties on two parameters were also discussed. Though the relation between consumed energies and t10 of each sample can be described by classical breakage model, experimental data of all samples were scatter. In this case, particle size and ash content were modelled into breakage equation in exponential term, namely t10 = A × (1 − e−b∙x∙Ecs/eYa). This modified model gave good fitting results to experimental data. Introduce of coal properties into energy-size reduction model helps to compare grinding energy efficiency of various coals. Confidence analyses of repeat experiments demonstrated the repeatability of test results and indicated the reliability of new breakage model.

In this study, the strengthening of the density segregation in a gas-solid fluidized bed is evaluated by applying an external electric field to recover residual metals from fine particles of the non-metallic fraction of waste printed circuit boards. The results demonstrate that large amounts of metals remain in the fine non-metallic fraction of the waste printed circuit boards and account for 21.93 wt%. The main residual metals are Fe, Cu, Sn, Zn, Mg, and Pb, and their contents are 6.06 wt%, 5.35 wt%, 2.92 wt%, 1.99 wt%, 1.36 wt%, and 1.31 wt%, respectively. The external electric field apparently influences the fluidization characteristics by changing the hydrodynamics and the bubble motions in the gas-solid fluidized bed. The minimum fluidized air flow velocity is larger in a fluidized bed with an electric field than in a common fluidized bed. After applying the electric field, the bed expansion increases from 1.15 to 1.21, the gas is well-distributed, and the interaction between the gas and the solid is enhanced. The horizontal motion of the particles can break the agglomeration of glass fibers and loosen the gas-solid bed, which results in an increase in the metal recovery from 67.61% to 76.61%. Based on this research, a novel recycling flowchart of fine waste printed circuit boards is proposed.

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.

To investigate the effect of size and density on the segregation of particles in the static classifier of vertical spindle mill, classification tests of coal were conducted in a lab-scale classifie...