Metal separation from mixed types of batteries using selective precipitation and liquid-liquid extraction techniques

The purpose of this paper is to study metal separation from a sample composed of a mixture of the main types of spent household batteries, using a hydrometallurgical route, comparing selective precipitation and liquid-liquid extraction separation techniques. The preparation of the solution consisted of: grinding the waste of mixed batteries, reduction and volatile metals elimination using electric furnace and acid leaching. From this solution two different routes were studied: selective precipitation with sodium hydroxide and liquid-liquid extraction using Cyanex 272 [bis(2,4,4-trimethylpentyl) phosphoric acid] as extracting agent. The best results were obtained from liquid-liquid extraction in which Zn had a 99% extraction rate at pH 2.5. More than 95% Fe was extracted at pH 7.0, the same pH at which more than 90% Ce was extracted. About 88% Mn, Cr and Co was extracted at this pH. At pH 3.0, more than 85% Ni was extracted, and at pH 3.5 more than 80% of Cd and La was extracted.     

Recovery of lithium and cobalt from waste lithium ion batteries of mobile phone

In view of the stringent environmental regulations, availability of limited natural resources and ever increasing need of alternative energy critical elements, an environmental eco-friendly leaching process is reported for the recovery of lithium and cobalt from the cathode active materials of spent lithium-ion batteries of mobile phones. The experiments were carried out to optimize the process parameters for the recovery of lithium and cobalt by varying the concentration of leachant, pulp density, reductant volume and temperature. Leaching with 2 M sulfuric acid with the addition of 5% H₂O₂ (v/v) at a pulp density of 100 g/L and 75 °C resulted in the recovery of 99.1% lithium and 70.0% cobalt in 60 min. H₂O₂ in sulfuric acid solution acts as an effective reducing agent, which enhance the percentage leaching of metals. Leaching kinetics of lithium in sulfuric acid fitted well to the chemical controlled reaction model i.e. 1 ? (1 ? X)^1/3 = k_ct. Leaching kinetics of cobalt fitted well to the model ‘ash diffusion control dense constant sizes spherical particles’ i.e. 1 ? 3(1 ? X)^2/3 + 2(1 ? X) = k_ct. Metals could subsequently be separated selectively from the leach liquor by solvent extraction process to produce their salts by crystallization process from the purified solution.     

Removal of batteries from solid waste using trommel separation

This paper describes the design and testing of a trommel for separation of batteries from solid waste. A trommel is a cylindrical separation device that rotates and performs size separation. It has also been used in areas such as municipal solid waste (MSW) processing, classifying construction and demolition debris, screening mass-burn incinerator ash and compost processing. A trommel has been designed based on size separation to separate household batteries from solid waste, which can then be used as feedstock for alternative applications of solid waste combustion, particularly where the metal content of the product is also a critical parameter, such as the Co-Co process for integrated cement and power production. This trommel has been tested with batches of university office and restaurant wastes against various factors. The recovery efficiency of batteries increases with decreasing inclination angle of the trommel and decreasing rotational speed. A physical characterization of the university solid waste has been performed with a 20-kg sample of the tested waste. It was found that there is a trend of decreasing recovery of batteries with increasing paper composition, and a trend of increasing recovery of batteries with increasing organic materials composition.     

Identification and thermomechanical characterization of polymers recovered from mobile phone waste

The plastic components from waste mobile phones were sorted and characterized using visual, spectroscopic and thermal methods. The sustainable strength of the recovered plastics was investigated by comparing their mechanical and thermal properties with commercially used reference materials. The results revealed that the recovered polymers have significant potential to be reused. However, some properties, such as impact strength and tensile modulus, are significantly low compared to virgin materials and need further improvement. The samples were also tested for brominated flame retardants (BFRs) using gas chromatography–mass spectrometry technique, and the results indicated the absence of BFR in recovered plastics; hence, these can be processed without any risk of BFR toxicity.     

Sustainable extraction of hazardous metals from crystal glass waste using biodegradable chelating agents

Journal of Material Cycles and Waste Management - Extraction of hazardous metals from dumped crystal glass waste was investigated for site decontamination and resource recovery. Mechanically...     

The separation of waste printed circuit board by dissolving bromine epoxy resin using organic solvent

Separation of waste printed circuit boards (WPCBs) has been a bottleneck in WPCBs resource processing. In this study, the separation of WPCBs was performed using dimethyl sulfoxide (DMSO) as a solvent. Various parameters, which included solid to liquid ratio, temperature, WPCB sizes, and time, were studied to understand the separation of WPCBs by dissolving bromine epoxy resin using DMSO. Experimental results showed that the concentration of dissolving the bromine epoxy resin increased with increasing various parameters. The optimum condition of complete separation of WPCBs was solid to liquid ratio of 1:7 and WPCB sizes of 16 mm² at 145 °C for 60 min. The used DMSO was vapored under the decompression, which obtained the regenerated DMSO and dissolved bromine epoxy resin. This clean and non-polluting technology offers a new way to separate valuable materials from WPCBs and prevent the environmental pollution of waste printed circuit boards effectively.     

Leaching kinetics of valuable metals from waste Li-ion batteries using neural network approach

Journal of Material Cycles and Waste Management - The kinetic study of valuable metals recovery from waste lithium-ion batteries (LIBs) using the artificial neural network (ANN) was investigated. A...     

Metal toxicity assessment of mobile phone parts using Milli Q water

Environmentally safe disposal of end-of-life (EoL) or discarded mobile phone is a serious problem on account of their ever increasing number and toxic metals contents. In the present work, metal toxicity of mobile phone plastics, printed wire boards (PWBs) and batteries were assessed through dynamic batch leaching using Milli Q (MQ) water. Phone plastics failed Toxicity Characterization Leaching Procedure (TCLP) and Waste Extraction Test (WET) for Pb as the cumulative amount of Pb leached from plastics (5.33 mg/l) exceeded the regulatory limits (5.0 mg/l) used in characterizing a waste as hazardous. Similarly, the average cumulative amount (21.83 mg/l) of Ni leached from PWBs exceeded the regulatory limit of 20 mg/l and thus PWBs failed WET. Metals leached from batteries in small amounts (Cr: 0.40 mg/l and Ni: 0.15 mg/l). The presence of Fe in the batteries and its precipitation as oxides/hydroxides in the leaching solution hindered the leaching of other metals in MQ water. Both plastics and PWBs should be treated as hazardous waste and should not be disposed in open landfills. Further, MQ water leaching could provide good simulation of metals leaching from the mobile phones disposed at landfill sites.     

Characterization and recycling of lithium nickel manganese cobalt oxide type spent mobile phone batteries based on mineral processing technology

Journal of Material Cycles and Waste Management - The unprecedented increase in mobile phone spent lithium-ion batteries (LIBs) in recent times has become a major concern for the global community....     

Evaluating source separation of plastic waste using conjoint analysis

Using conjoint analysis, we estimated the willingness to pay (WTP) of households for source separation of plastic waste and the improvement of related environmental impacts, the residents' loss of life expectancy (LLE), the landfill capacity, and the CO(2) emissions. Unreliable respondents were identified and removed from the sample based on their answers to follow-up questions. It was found that the utility associated with reducing LLE and with the landfill capacity were both well expressed by logarithmic functions, but that residents were indifferent to the level of CO(2) emissions even though they approved of CO(2) reduction. In addition, residents derived utility from the act of separating plastic waste, irrespective of its environmental impacts; that is, they were willing to practice the separation of plastic waste at home in anticipation of its "invisible effects", such as the improvement of citizens' attitudes toward solid waste issues.     

Optimization of metal bio-acid leaching from mobile phone printed circuit boards using natural organic acids and H2O2

Journal of Material Cycles and Waste Management - With increased popularity and technological innovation, more and more electric and electronic equipment wastes (e-wastes) are being generated....     

Removal of iron from waste printed circuit board dust: surfactant assisted magnetic separation versus selective leaching routes

Journal of Material Cycles and Waste Management - Iron content in printed circuit board (PCB) dust consumes complexing agents, compromises recovery and contaminates leach solution during precious...     

Absorption of odourous substances using selective gas-liquid separation processes

Absorption is one of the most widely used techniques for treating odourous waste gases. An improvement of the effectiveness of gas scrubbers can be achieved by using adapted washing liquids. A screening test is proposed as a low cost tool for testing washing liquids on industrial waste gases. The odour index is used to identify the main cause of the specific smell and to simplify the analysis of absorptive performances of washing liquids. The method is verified by experiments at a chocolate factory and a fat and oil refinery.     

Development of Mn recovery process from waste dry cell batteries

High-purity Mn is necessary for high strength steel production. However, the availability of metal Mn is limited to a few countries. Therefore, as an alternative to direct purchasing of metal Mn, a process for Mn recovery was investigated. Waste dry cell batteries are considered to be one of the most feasible Mn sources. We have developed a high efficiency chemical separation system. This system consists of a three-phase chemical treatment. In the first phase, the metal components of the waste dry cell batteries were dissolved by acid, along with a reducing agent. Afterward, the undissolved carbon particles were separated by filtration. In the second phase, the dissolved Mn was selectively precipitated as manganese oxide by O₃ oxidation. Then, the precipitated manganese oxide was separated from the other metal components by filtration. Finally, in the third phase, the manganese oxide was reduced to high-purity Mn using an electric furnace.     

Electrical separation of plastics coming from special waste

Minimisation of waste to landfilling is recognised as a priority in waste management by European rules. In order to achieve this goal, developing suitable technologies for waste recycling is therefore of great importance. To achieve this aim the technologies utilised for mineral processing can be taken into consideration to develop recycling systems. In particular comminution and separation processes can be adopted to recover valuable materials from composite waste. In this work the possibility of recycling pharmaceutical blister packaging has been investigated. A suitable comminution process has been applied in order to obtain the liberation of the plastic and aluminium components. Experiments of electrical separation have been carried out in order to point out the influence of the process parameters on the selections of the different materials and to set up the optimum operating conditions.     

Combination of three-stage sink-float method and selective flotation technique for separation of mixed post-consumer plastic waste

The aim of this research was to separate the different plastics of a mixed post-consumer plastic waste by the combination of a three-stage sink-float method and selective flotation. By using the three-stage sink-float method, six mixed-plastic wastes, belonging to the 0.3-0.5 cm size class and including high density polyethylene (HDPE), polypropylene (PP), polyvinylchloride (PVC), polystyrene (PS), polyethylene terephthalate (PET) and acrylonitrile-butadiene-styrene copolymers (ABS) were separated into two groups, i.e., a low density plastic group (HDPE and PP) and a high density plastic group (PET, PVC, PS and ABS) by tap water. Plastic whose density is less than that of the medium solution floats to the surface, while the one whose density is greater than that of the medium solution sinks to the bottom. The experimental results elucidated that complete separation of HDPE from PP was achieved by the three-stage sink-float method with 50% v/v ethyl alcohol. To succeed in the separation of a PS/ABS mixture from a PET/PVC mixture by the three-stage sink-float method, a 30% w/v calcium chloride solution was employed. To further separate post-consumer PET/PVC and PS/ABS based on plastic type, selective flotation was carried out. In order to succeed in selective flotation separation, it is necessary to render hydrophilic the surface of one or more species while the others are kept in a hydrophobic state. In flotation studies, the effects of wetting agent, frother, pH of solution and electrolyte on separation were determined. The selective flotation results showed that when using 500 mg l(-1) calcium lignosulfonate, 0.01 ppm MIBC, and 0.1 mg l(-1) CaCl2 at pH 11, PET could be separated from PVC. To separate ABS from PS, 200 mg l(-1) calcium lignosulfonate and 0.1 mg l(-1) CaCl2 at pH 7 were used as a flotation solution. Wettability of plastic increases when adding CaCl2 and corresponds to a decrease in its contact angles and to a reduction in the recovery of plastic in the floated product.     

Recovery of silicon powder from kerf loss slurry waste using superconducting high gradient magnetic separation technology

A major challenge in recycling of silicon powder from kerf loss slurry waste is the complete removal of metal particles. The traditional acid leaching method is costly and not green. In this paper, a novel approach to recover high-purity Si from the kerf loss slurry waste of solar grade silicon was investigated. The metal impurities were removed with superconducting high gradient magnetic separation technology. The effects of process parameters such as magnetic flux density, slurry density, and slurry flow velocity on the removal efficiency were investigated, and the parameters were optimized. In one lot of control experiments, the silicon content was increased from 90.91 to 95.83%, iron content reduced from 3.24 to 0.57%, and aluminum content from 2.44 to 1.51% under the optimum conditions of magnetic flux density of 4.0 T, slurry density of 20 g/L, and slurry flow velocity of 500 mL/min. The result indicates that the superconducting high gradient magnetic separation technology is a feasible purifying method, and the magnetic separation concentrate could be used as an intermediate product for high-purity Si powder.

     

从废旧锌锰电池中回收汞和铵的工艺研究

针对废旧锌锰电池中汞分散存在给回收处理废旧锌锰电池工作完全回收汞所带来的困难,利用汞和铵的性质特点,找到了从废旧锌锰电池中集中回收汞和铵的工艺条件,为废旧锌锰电池的资源化和防止二次污染创造了有利条件.     

Chemical stabilization of medical waste fly ash using chelating agent and phosphates: Heavy metals and ecotoxicity evaluation

Chemical stabilization of heavy metals in medical waste fly ash has been carried out using the following compounds: a chelating agent (Ashnite S803), a commercial acidic phosphoric acid solution (Ashnite R303) as well as basic one (Ashnite R201). In order to predict the leachability of heavy metals, Japanese Leaching Test (JLT-13) procedure was applied to the stabilized fly ash products. An ecotoxicity assessment of the stabilized fly ash products leachate and the unstabilized fly ash leachate was conducted using a battery of bioassays based on lettuce root elongation inhibition, Daphnia magna mortality and Vibrio fischeri photoinhibition. The results showed that the three stabilizing agents were able to significantly decrease (ANOVA, P < 0.05) the concentration of heavy metals in the leachates. Although the leachate from both stabilized and unstabilized fly ash were very toxic to lettuce and daphnids, the incorporation of these stabilizing agents diminished significantly (ANOVA, P < 0.05) the toxicity of the leachates towards the three tested organisms. Pearson correlation analysis was used to analyze the strength of the relationship between chemical elements concentration in the leachate and bioassays results. Most of the heavy metals in the leachate were significantly correlated (ANOVA, P < 0.05) with the toxicity values of the bioassays. However, the correlation was not found between the concentration of dissolved organic carbon (DOC) and the toxicity effect of the leachate to the tested organisms.     

Modeling of manganese recovery from waste Li-ion batteries by gene expression programming

Journal of Material Cycles and Waste Management - Modeling of leaching process as a function of operational variables can specify an accurate perspective in the forecasting of valuable...