Simple Preparation of Ni and NiO Nanoparticles Using Raffinate Solution Originated from Spent NiMH Battery Recycling

Nickel (Ni) and nickel oxide (NiO) nanoparticles were produced by a combination of precipitation and reduction/calcination methods using the raffinate solution originated from laboratory scale spent NiMH recovery process. Ni recovery from the solution reached 99.8% by a simple precipitation step using baking soda. X-ray diffraction, FTIR spectroscopy, carbon analyzer and thermal gravimetric analysis techniques were used to characterize the precipitate. Metallic and oxide nanoparticles were obtained by hydrogen reduction and calcination under air atmosphere of the precipitate at 400\ua0\ub0C, respectively for 30–90\ua0min residence times. The crystal structure, crystallite size, morphology, particle size and surface area of the samples, as well as carbon residue content in the particles were detected by particle characterization methods. The results indicate that spherical Ni nanoparticles have a crystallite size about 37\ua0nm, and particle sizes of around 100\ua0nm. The agglomeration of the nanoparticles reduces by increasing residence time. NiO nanoparticles have finer crystallite and particle sizes than the metallic samples produced at the same temperature and residence times. The results show that the combination of the simple methods presented can be an alternative process for producing advanced particles from spent NiMH batteries

Investigation of indium and other valuable metals leaching from unground waste LCD screens by organic and inorganic acid leaching

Indium (In) is the indispensable part of liquid crystal display (LCD) screen which is applied as a thin semiconductor layer on the surface mainly in the form of indium tin oxide (ITO), and feasible end-of-life recycling of indium from this electronic devices is technologically challenging. The present study investigates the recovery of indium from spent untreated liquid crystal display (LCD) screen by inorganic and organic leaching. Critical process parameters such as effects of different acids, leaching duration, reusability of acidic solution and both sides of the organic layers on the LCD were studied to optimize the indium leaching from the waste screen. The efficiencies of inorganic acids (nitric and sulfuric) and organic acids (citric, glycolic, L-ascorbic, maleic and DL-tartaric) to leach metals on LCD were investigated in different leaching duration from 3 to 168 h. Extracted metal concentrations and dissolved organics are characterized by inductively coupled plasma with mass spectrometry and total organic carbon analyser, respectively. The results indicate that over 90% extraction of indium and the lowest amount of other impurities can be achieved using 1 M H2SO4 for a leaching period of 48 h. Moreover, similar results could reach with 1 M HNO3, while organic acids were less successful under these conditions. Overall, the indium amount could reach up to 69 mg/kgITO glass for the front and 31 mg/kgITO glass for the back side glass. However, relatively high amount of organic layer from LCD screen dissolves in nitric acid solution up to 4000 mgTOC/l, which can affect the further stages of a recycling process. Besides, aluminium, zinc and tin were identified as the elements with the highest amount with indium in the leachate. All these elements were found in both, glass and organic layer of the LCD screen. Although metals from LCD screen have limited solubility in organic acids, specifically tartaric acid has a selective extraction behaviour for molybdenum. By reusing the leachate for further leaching processes, the concentration of indium could be increased constantly up to five times, which indicates that it is possible to increase the indium concentration to the industrially processable amount

Electrolyte recovery from spent Lithium-Ion batteries using a low temperature thermal treatment process

Electrolyte recovery is seldomly considered in state-of-art lithium-ion battery recycling methods but rather evaporates and decomposes uncontrolled during the pre-treatment steps. However, controlled and safe removal of the electrolyte is inevitable and of high importance to the recycling industry to minimize the environmental impact of the recycling processes by preventing severe threats produced by the inflammable, toxic and hazardous components of the electrolyte. This study investigated the effects of temperature and process time of a low temperature thermal treatment process on electrolyte recovery. The process exhaust gases and recovered products were analyzed by In-Situ Fourier-transform infrared spectroscopy (FT-IR) and gas chromatography-mass spectrometry (GC–MS) to determine the effectiveness of the significant process parameters. The results show that the electrolyte solvents, which are dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and ethylene carbonate (EC), were successfully recovered for 80\ua0minutes of processing time at 130\ua0\ub0C. The LiPF6 decomposition products hydrogen fluoride (HF) and phosphoryl fluoride (POF3) were detected in the exhaust gas stream and recovered as acidic solutions. Thermal treatment below 150\ua0\ub0C is a promising approach for the recovery of the electrolyte solvents prior to the metal recycling stage due to its simplicity, feasibility, and environmental benefit

Valuable metal recycling from thin film CIGS solar cells by leaching under mild conditions

The increase in the manufacturing of copper-indium-gallium-diselenide (CIGS) thin film photovoltaics is accompanied by a growing amount of production waste, which contains a mixture of valuable, critical and hazardous elements. However, industrial recovery and reuse processes of these elements for production of new photovoltaics are still absent. In this paper, the possibility of using benign leaching conditions for recovering mainly silver and indium from production waste flexible CIGS solar cells was investigated, along with the contamination levels from other industrial elements in the leachate. At the same time, the prospect of selective leaching of contaminants was assessed, aiming to purer streams of the valuable metals and thus their reuse in new products. The results show an increase in the leaching yields of Ag and In when acid concentration and surface to liquid ratio (A:L) increase, however, this is also true for contamination. A complete Ag recovery and 85% recovery of In was achieved with 2 M HNO3 and A:L equal to 1:3 cm2/ml after 24 h of leaching at room temperature. Under the same conditions, leaching with 0.5 M HNO3 extracts 85% Ag and 30% In, with correspondingly reduced contamination levels. Finally, leaching with 0.1 M HNO3 proved to be promising for achievement of higher Ag purity through an initial step of Zn selective leaching for 1 h

Sintering and properties of ZrO[2](Mg)-MgO composites

These studies shows which structures and properties have composites based on ZrO[2](Mg)-MgO sintered in a wide temperature range from 1400to 1650{о}С. X-ray diffraction showed an increasing of crystalline size with increasing of magnesia concentration. Decreasing of sintering temperature accompanied with an increasing of porosity and reduction of the compressive strength. Scanning electron microscopy showed the morphology of the composite structure. It is discovered that the pore size in the zirconia matrix in an order of magnitude higher than in magnesia inclusions

Innovative recycling of organic binders from electric vehicle lithium-ion batteries by supercritical carbon dioxide extraction

The growing demand for energy storage devices due to the skyrocketing production/consumption of portable electrical and electronic equipment as well as electric vehicles has promoted battery technologies, resulting in the piling of a large number of waste lithium-ion batteries (LIBs). Organic binders wrapped on electrode particles are usually the main reason that causes the difficulty of liberation and extraction of electrode materials. Pyrolysis or incineration is the general approach to separate the organic binder, leading to fluorinated exhaust gas emissions. In this study, the supercritical carbon dioxide (SC CO ) combined with a cosolvent dimethyl sulfoxide was innovatively adapted to enable the extraction of organic binders from spent LIBs to facilitate the liberation of the cathode material from aluminum foil. Pure polyvinylidene fluoride was preferentially used to study the SC CO dissolution mechanism. The results indicate that 98.5 wt% polyvinylidene fluoride (PVDF) dissolves in SC CO dimethyl sulfoxide system under the optimum conditions; 70\ub0C process temperature, 80 bar pressure, and 13 min duration. After removing PVDF, the recovered sample was characterized by Fourier Transform Infrared Spectrometer (FTIR) and thermogravimetric analyzer (TGA) to observe its possible re-utilization. It is clear that the surficial chemical groups and content remained the same after treatment. SC CO processing effectively liberates the active cathode material from the aluminum substrate due to removal of the binder. The suggested innovative approach is promising as an alternative pretreatment method due to its high efficiency, relatively low energy consumption, and environmentally friendly features

Physical separation, mechanical enrichment and recycling-oriented characterization of spent NiMH batteries

Nickel–metal hydride (NiMH) batteries contain high amount of industrial metals, especially iron, nickel, cobalt and rare earth elements. Although the battery waste is a considerable secondary source for metal and chemical industries, a recycling process requires a suitable pretreatment method before proceeding with recovery step to reclaim all valuable elements. In this study, AA- and AAA-type spent NiMH batteries were ground and then sieved for size measurement and classification. Chemical composition of the ground battery black mass and sorted six different size fractions were determined by an analytical technique. Crystal structures of the samples were analyzed by X-ray diffraction. Results show that after mechanical treatment, almost 87\ua0wt% of the spent NiMH batteries are suitable for further recycling steps. Size classification by sieving enriched the iron content of the samples in the coarse fraction which is bigger than 0.25\ua0mm. On the other hand, the amounts of nickel and rare earth elements increased by decreasing sample size, and concentrated in the finer fractions. Anode and cathode active materials that are hydrogen storage alloy and nickel hydroxide were mainly collected in finer size fraction of the battery black mass

Mixed oxides NiO/ZnO/Al2O3 synthesized in a single step via ultrasonic spray pyrolysis (USP) method

Mixed oxides have received remarkable attention due to the many opportunities to adjust their interesting structural, electrical, catalytic properties, leading to a better, more useful performance compared to the basic metal oxides. In this study, mixed oxides NiO/ZnO/Al2O3 were synthesized in a single step via the ultrasonic spray pyrolysis method using nitrate salts, and the temperature effects of the process were investigated (400, 600, 800 \ub0C). The synthesized samples were characterized by means of scanning electron microscopy, energy-dispersive spectroscopy, X-ray diffraction and Raman spectroscopy analyses. The results showed Al2O3, NiO–Al2O3 and ZnO–Al2O3 systems with spinel phases. Furthermore, the Raman peaks supported the coexistence of oxide phases, which strongly impact the overall properties of nanocomposite

Hydrometallurgical recycling of EV lithium-ion batteries: Effects of incineration on the leaching efficiency of metals using sulfuric acid

The growing demand for lithium-ion batteries will result in an increasing flow of spent batteries, which must be recycled to prevent environmental and health problems, while helping to mitigate the raw materials dependence and risks of shortage and promoting a circular economy. Combining pyrometallurgical and hydrometallurgical recycling approaches has been the focus of recent studies, since it can bring many advantages. In this work, the effects of incineration on the leaching efficiency of metals from EV LIBs were evaluated. The thermal process was applied as a pre-treatment for the electrode material, aiming for carbothermic reduction of the valuable metals by the graphite contained in the waste. Leaching efficiencies above 70% were obtained for Li, Mn, Ni and Co after 60 min of leaching even when using 0.5 M sulfuric acid, which can be linked to the formation of more easily leachable compounds during the incineration process. When the incineration temperature was increased (600–700 \ub0C), the intensity of graphite signals decreased and other oxides were identified, possibly due to the increase in oxidative conditions. Higher leaching efficiencies of Mn, Ni, Co, and Li were reached at lower temperatures of incineration (400–500 \ub0C) and at higher leaching times, which could be related to the partial carbothermic reduction of the metals