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 wt% 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 mm. 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.     

Organic oxalate as leachant and precipitant for the recovery of valuable metals from spent lithium-ion batteries

Spent lithium-ion batteries containing lots of strategic resources such as cobalt and lithium are considered as an attractive secondary resource. In this work, an environmentally compatible process based on vacuum pyrolysis, oxalate leaching and precipitation is applied to recover cobalt and lithium from spent lithium-ion batteries. Oxalate is introduced as leaching reagent meanwhile as precipitant which leaches and precipitates cobalt from LiCoO(2) and CoO directly as CoC(2)O(4)·2H(2)O with 1.0 M oxalate solution at 80°C and solid/liquid ratio of 50 g L(-1) for 120 min. The reaction efficiency of more than 98% of LiCoO(2) can be achieved and cobalt and lithium can also be separated efficiently during the hydrometallurgical process. The combined process is simple and adequate for the recovery of valuable metals from spent lithium-ion batteries.     

Chemical and physical characterization of electrode materials of spent sealed Ni-Cd batteries

The present work aimed at the chemical and physical characterization of spent sealed MONO-type Ni-Cd batteries, contributing to a better definition of the recycling process of these spent products. The electrode material containing essentially nickel, cadmium and some cobalt corresponds to approximately 49% of the weight of the batteries. The remaining components are the steel parts from the external case and the supporting grids (40%) containing Fe and Ni, the electrolyte (9%) and the plastic components (2%). Elemental quantitative analysis showed that the electrodes are highly concentrated in metals. The phase identification achieved by X-ray powder diffraction combined with chemical analysis and leaching tests allowed the authors to proceed with the composition of the electrode materials as following: cathode: 28.7% metallic Ni, 53.3% Ni(OH)2, 6.8% Cd(OH)2 and 2.8% Co(OH)2; anode: 39.4% metallic Ni and 57.0% Cd(OH)2. The morphology of the electrodes was studied by microscopic techniques and two phases were observed in the electrodes: (1) a bright metallic phase constituted of small nickel grains that acts as conductor, and (2) the main hydroxide phase of the active electrodes into which the nickel grains are dispersed. The disaggregation of the electrode particles from the supporting plates was easily obtained during the dismantling procedures, indicating that a substantial percentage of the electrodes can be efficiently separated by wet sieving after shredding the spent batteries.     

酸浸—萃取—沉淀法回收废锂离子电池中的钴

采用酸浸—萃取—沉淀法回收废锂离子电池中的钴。实验结果表明:废锂离子电池在600℃下煅烧5 h可将正极材料上的有机黏结剂与正极活性物质分离;正极活性物质在Na OH溶液浓度为2.0 mol/L、n(Na OH)∶n(铝)=2.5、碱浸温度为20℃的条件下碱浸反应1 h后,铝浸出率达99.7%;已除铝的正极活性物质在硫酸浓度为2.5 mol/L、H_2O_2质量浓度为7.25 g/L、液固比为10、酸浸温度为85℃的条件下酸浸反应120 min,钴浸出率高达98.0%;酸浸液在p H为3.5、萃取剂P507与Cyanex272体积比为1∶1的条件下,经2级萃取,钴萃取率为95.5%;采用H_2SO_4溶液反萃后在硫化钠质量浓度为8 g/L、反萃液p H为4的条件下沉淀反应10 min,钴沉淀率达99.9%。     

氨基磺酸溶液浸出废锂离子电池负极活性材料中的锂

随着锂离子电池的广泛应用,产生了大量废锂离子电池,其负极活性材料中积累了高品位的锂。锂作为一种稀有金属,对其进行回收利用很有意义。选取了无毒、稳定性好的氨基磺酸作为浸出剂,浸取废锂离子电池负极活性材料中的锂,考察了预处理方式对负极活性材料成分和结构的影响以及浸出条件对锂浸出率的影响。结果表明:600℃下煅烧4 h,可完全去除附着在负极活性材料表面的有机物;在氨基磺酸浓度0.75 mol/L、固液比5 g/L、浸出温度40℃、浸出时间45 min的最佳浸出条件下,负极活性材料中锂浸出率达97.2%。     

Evaluation of heavy metal leaching from spent household batteries disposed in municipal solid waste

Batch leaching tests and simulated landfill lysimeter tests were performed to evaluate the contents of heavy metals leached from spent batteries in the municipal solid waste. The toxicity characteristic leaching procedure was utilized to perform the batch leaching tests of 36 spent batteries. Four lysimeters were prepared with battery contents ranging from 0% to 100% by weight for column tests, and the experiments were performed at ambient temperature. The age of all the batteries used in the study ranged from freshly disposed up to approximately 3 years old. The results from the batch tests showed that the type of battery influenced the heavy metal concentrations in the leached solutions. The lysimeter experiment results illustrated that at lower pH levels more metals are leached than at higher pH levels. The increasing amount of batteries disposed in landfills can contribute to the leaching of more metals, especially Mn and Zn, into the environment. These results indicate that the direct disposal of spent household batteries into a MSW landfill can increase the heavy metal contents in the landfill leachate.     

Study concerning the recovery of zinc and manganese from spent batteries by hydrometallurgical processes

Used batteries contain numerous metals in high concentrations and if not disposed of with proper care, they can negatively affect our environment. These metals represent 83% of all spent batteries and therefore it is important to recover metals such as Zn and Mn, and reuse them for the production of new batteries. The recovery of Zn and Mn from used batteries, in particular from Zn–C and alkaline ones has been researched using hydrometallurgical methods. After comminution and classification of elemental components, the electrode paste resulting from these processes was treated by chemical leaching. Prior to the leaching process the electrode paste has been subjected to two washing steps, in order to remove the potassium, which is an inconvenient element in this type of processes. To simultaneously extract Zn and Mn from this paste, the leaching method in alkaline medium (NaOH solution) and acid medium (sulphuric acid solution) was used. Also, to determine the efficiency of extraction of Zn and Mn from used batteries, the following variables were studied: reagents concentration, S/L ratio, temperature, time. The best results for extraction yield of Zn and Mn were obtained under acid leaching conditions (2 M H₂SO₄, 1 h, 80 °C).     

Bioleaching of metals from spent lithium ion secondary batteries using Acidithiobacillus ferrooxidans

Bioleaching of spent lithium ion secondary batteries, containing LiCoO2, was attempted in this investigation. The present study was carried out using chemolithotrophic and acidophilic bacteria Acidithiobacillus ferrooxidans, which utilized elemental sulfur and ferrous ion as the energy source to produce metabolites like sulfuric acids and ferric ion in the leaching medium. These metabolites helped dissolve metals from spent batteries. Bio-dissolution of cobalt was found to be faster than lithium. The effect of initial Fe(II) concentration, initial pH and solid/liquid (w/v) ratio during bioleaching of spent battery wastes were studied in detail. Higher Fe(II) concentration showed a decrease in dissolution due co-precipitation of Fe(III) with the metals in the residues. The higher solid/liquid ratio (w/v) also affected the metal dissolution by arresting the cell growth due to increased metal concentration in the waste sample. An EDXA mapping was carried out to compare the solubility of both cobalt and lithium, and the slow dissolution rate was clearly found from the figures.     

黄钠铁矾法氧化去除废锂电池硫酸浸出液中的铁

废锂电池中含有的Co、Ni和Cu等金属具有回收价值,Fe的存在降低了有价金属的回收效率。为去除废锂电池硫酸浸出液中的Fe,采用黄钠铁矾法分别以氯酸钠和过氧化氢作为氧化剂氧化除Fe,并优化了过氧化氢作为氧化剂的除Fe工艺参数。实验结果表明:过氧化氢作为氧化剂的除Fe效果好于氯酸钠;在n(H2O2)∶n(Fe)=0.5、初始溶液pH为1.8、终点pH为2.5、反应时间为2.0 h、搅拌速率为500 r/min的最佳工艺条件下,初始ρ(Fe)为0.212g/L的硫酸浸出液经除Fe处理后ρ(Fe)小于0.004 g/L,Fe去除率达98.0%,Co、Ni和Cu的损失率分别为1.04%、2.17%和1.41%。     

Recycling of spent nickel-cadmium batteries based on bioleaching process

Only 1-2 percent of discarded dry batteries are recovered in China. It is necessary to find an economic and environmentally friendly process to recycle dry batteries in this developing country. Bioleaching is one of the few techniques applicable for the recovery of the toxic metals from hazardous spent batteries. Its principle is the microbial production of sulphuric acid and simultaneous leaching of metals. In this study, a system consisting of a bioreactor, settling tank and leaching reactor was developed to leach metals from nickel-cadmium batteries. Indigenous thiobacilli, proliferated by using nutritive elements in sewage sludge and elemental sulphur as substrates, was employed in the bioreactor to produce sulphuric acid. The overflow from the bioreactor was conducted into the settling tank. The supernatant in the settling tank was conducted into the leaching reactor, which contained the anode and cathodic electrodes obtained from nickel-cadmium batteries. The results showed that this system was valid to leach metals from nickel-cadmium batteries, and that the sludge drained from the bottom of the settling tank could satisfy the requirements of environmental protection agencies regarding agricultural use.     

An overview on the processes and technologies for recycling cathodic active materials from spent lithium-ion batteries

This paper aims to make an overview on the current status and new tendency for recycling cathodic active materials from spent lithium-ion batteries. Firstly, it introduces several kinds of pretreatment technologies, followed by the summary of all kinds of single recycling processes mainly focusing on organic acid leaching and synergistic extraction. Then, several examples of typical combined processes and industrial recycling processes are presented in detail. Meanwhile, the advantages, disadvantages and prospect of each single process, combined process, as well as industrial recycling processes, are discussed. Finally, based on a novel acidic organic solvent, the authors briefly introduce an environmental friendly process to directly recycle and resynthesize cathodic active material LiNi_1/3Co_1/3Mn_1/3O₂ from spent lithium-ion batteries. The preliminary experimental results demonstrated the advantages of low reaction temperature, high separation efficiency and organic solvent cycling and preventing secondary pollution to the environment. This process may be used for large-scale recycling of spent lithium-ion batteries after further study.     

Recovery of manganese oxides from spent alkaline and zinc–carbon batteries. An application as catalysts for VOCs elimination

Manganese, in the form of oxide, was recovered from spent alkaline and zinc–carbon batteries employing a biohydrometallurgy process, using a pilot plant consisting in: an air-lift bioreactor (containing an acid-reducing medium produced by an Acidithiobacillus thiooxidans bacteria immobilized on elemental sulfur); a leaching reactor (were battery powder is mixed with the acid-reducing medium) and a recovery reactor. Two different manganese oxides were recovered from the leachate liquor: one of them by electrolysis (EMO) and the other by a chemical precipitation with KMnO₄ solution (CMO). The non-leached solid residue was also studied (RMO). The solids were compared with a MnO_x synthesized in our laboratory.The characterization by XRD, FTIR and XPS reveal the presence of Mn₂O₃ in the EMO and the CMO samples, together with some Mn⁴⁺ cations. In the solid not extracted by acidic leaching (RMO) the main phase detected was Mn₃O₄.The catalytic performance of the oxides was studied in the complete oxidation of ethanol and heptane. Complete conversion of ethanol occurs at 200 °C, while heptane requires more than 400 °C. The CMO has the highest oxide selectivity to CO₂.The results show that manganese oxides obtained using spent alkaline and zinc–carbon batteries as raw materials, have an interesting performance as catalysts for elimination of VOCs.     

Tannic acid as a novel and green leaching reagent for cobalt and lithium recycling from spent lithium-ion batteries

Tannic acid–acetic acid is proposed as novel and green chemicals for cobalt and lithium recycling from spent lithium-ion batteries through a leaching process. The synergism of both acids was documented through batch and continuous studies. Tannic acid promotes cobalt dissolution by reducing insoluble Co³⁺ into soluble Co²⁺, while acetic acid is critical to improve the dissolution and stabilize the metals in the pregnant leach solution. Based on batch studies, the optimum conditions for metal recovery at room temperature are acetic acid 1 M, tannic acid 20 g/L, pulp density 20 g/L, and stirring speed 250 rpm (94% cobalt and 99% lithium recovery). The kinetic study shows that increasing temperature to 80 °C improves cobalt and lithium recovery from 65 to 90% (cobalt) and from 80 to 99% (lithium) within 4 h at sub-optimum condition (tannic acid 10 g/L). Kinetic modeling suggests the leaching process was endothermic, and high activation energy indicates a surface chemical process. For other metals, the pattern of manganese and nickel recovery trend follows the cobalt recovery trend. Copper recovery was negatively affected by tannic acid. Iron recovery was limited due to the weak acidic condition of pregnant leach solution, which is beneficial to improve leaching selectivity.

     

Consumer perspectives on household hazardous waste management in Japan

We give an overview of the management systems of household hazardous waste (HHW) in Japan and discuss the management systems and their risks. To get basic information, we conducted a survey of consumers to discover their behavior and awareness of HHW items throughout the entire life cycle, which is made up of the purchase, use, and disposal of a product. The results showed that many people hold end-of-life batteries, fluorescent lamps, empty spray cans, and others in their houses after use. Also, the results showed that a lot of such waste items were discarded in waste streams different from those stipulated by local governments. In particular, many people do not remove NiCd batteries inside products such as shavers or cordless phones before discarding. On the other hand, people’s knowledge of and concern regarding the risks, collection, and recycling of HHW were high. When information about the risks was specifically presented in the questionnaire, people tended to show a more positive intention to participate in a collection and recycling system compared to those who were not presented with such information. Our studies on NiCd batteries and fluorescent lamps showed that it is important to collect and recycle HHW to control the domestic and international flows of cadmium and mercury.     

Scenario analysis for recovery of rare earth elements from end-of-life vehicles

End-of-life vehicles (ELVs) are increasingly being recognized as a possible future resource pool for rare earth elements (REEs). This study provides the amount of REEs that can be recovered from ELVs in Japan based on dismantling survey, chemical identification and substance flow analysis. The REEs were quantified from common passenger vehicles and hybrid electric vehicles. We targeted 17 REEs in estimation of REE contents in ELVs. Four scenarios were developed to explore the recovery of REEs from ELVs. In these scenarios, NiMH batteries and motors containing NdFeB magnets were identified as target components due to they are main REEs carriers; we focused on interpretation of neodymium (Nd) and dysprosium (Dy) owing to they are two of the most critical REEs. The results suggest that 2700 (±500) tons of REEs can be recovered, of which 520 (±100) tons and 31 (±7) tons will be contributed by Nd and Dy in 2030. Meanwhile, the Dy recovered from ELVs can satisfy 23 % (±6 %) of the demand for NdFeB magnets and NiMH battery cells in automobile production of Japan; the Nd recovered from ELVs can satisfy 49 % (±9 %) of the production demands.     

Influence of H2SO4 and ferric iron on Cd bioleaching from spent Ni–Cd batteries

The paper is concerned with biohydrometallurgical methods of cadmium recovery from spent Ni–Cd batteries. Cd leaching efficiency from electrode material in different media (H₂SO₄ and Fe₂(SO₄)₃ solutions), at different Fe(III) concentrations and using the bacteria Acidithiobacillus ferrooxidans were investigated. The main aim of this study was to understand which from the bioleaching products (sulphuric acid or ferric sulphate) play a main role in the bioleaching process of Cd recovery. The influence of Fe ions on Cd leachability was confirmed. The best leaching efficiency of Cd (100%) was reached by bioleaching and also by leaching in Fe₂(SO₄)₃ solution. The results of X-ray diffraction confirmed that no cadmium was present in solid residuum obtained after the Cd bioleaching as well as Cd leaching using solely ferric iron. The use of H₂SO₄ solution resulted in the lowest efficiency of Cd leachability, the presence of hydroxides in electrode materials caused neutralization of the leaching solution and inhibition of Cd leaching.     

废无汞碱性电池极性材料制备锰锌铁氧体磁性纳米颗粒

以硝酸浸取废无汞碱性电池极性材料,再加入硝酸铁及蔗糖生成前驱体,最后通过焙烧制得锰锌铁氧体磁性纳米颗粒。优化了酸浸和焙烧条件,采用FTIR和DTA-TG技术研究了前驱体的形成和热解过程,采用XRD、FTIR、TEM技术和振动样品磁强计对锰锌铁氧体进行了表征。结果表明:废无汞碱性电池极性材料酸浸的最佳条件为H_2O_2加入量3%(w)、液固比10 mL/g、稀硝酸浓度4 mol/L、浸取温度40℃,该条件下浸取10 min锰和锌的浸出率均可达100%;所得前驱体为葡萄糖酸盐,其最佳焙烧条件为焙烧温度450℃、焙烧时间2 h;最佳条件下所得锰锌铁氧体为尖晶石型Mn_(0.5)Zn_(0.5)Fe_2O_4,其颗粒为球形、大小均匀,且磁性能优良。     

Thermal treatment for recovery of manganese and zinc from zinc-carbon and alkaline spent batteries

The aim of this paper is the recovery of manganese and zinc from a mixture of zinc-carbon and alkaline spent batteries, containing 40.9% of Mn and 30.1% of Zn, after preliminary physical treatment followed by removal of mercury. Separation of the metals has been carried out on the basis of their different boiling points, being 357°C and 906°C the boiling point of mercury and zinc and 1564°C the melting point of Mn(2)O(3). Characterization by chemical analysis, TGA/DTA and X-ray powder diffraction of the mixture has been carried out after comminution sieving and shaking table treatment to remove the anodic collectors and most of chlorides contained in the mixture. The mixture has been roasted at various temperatures and resident times in a flow of air to set the best conditions to remove mercury that were 400°C and 10min. After that, the flow of air has been turned into a nitrogen one (inert atmosphere) and the temperatures raised, thus permitting the zinc oxide to be reduced to metallic zinc by the carbon present in the original mixture and recovered after volatilization as a high grade concentrate, while manganese was left in the residue. The recovery and the grade of the two metals, at 1000°C and 30min residence time, were 84% and 100% for zinc and 85% and 63% for manganese, respectively. The recovery of zinc increased to 99% with a grade of 97% at 1200°C and 30min residence time, while the recovery and grade of manganese were 86% and 87%, respectively, at that temperature. Moreover, the chlorinated compounds that could form by the combustion of the plastics contained in the spent batteries, are destroyed at the temperature required by the process.     

用含硫化砷废渣制备砷酸铜

以湖北省某化工企业含砷废水处理过程中产生的含硫化砷废渣为研究对象,采用氧化碱浸—沉淀工艺制备砷酸铜。考察了沉淀反应液pH、沉淀反应温度、搅拌转速对砷沉淀效果的影响。采用XRD和SEM技术对砷酸铜的物相及形貌进行了表征。实验结果表明：废渣在氧化碱浸过程的砷浸出率为96.53%;沉淀反应时间为30 min时,沉淀步骤的最佳工艺条件为沉淀反应液pH 5.0、搅拌转速500 r/min、沉淀反应温度50 ℃。验证实验结果表明,在该工艺条件下,砷沉淀率均达93.96%以上。SEM表征结果显示,砷酸铜产品为颗粒状,粒径约为500 nm。XRD表征结果显示,砷酸铜产品中主要含有Cu₃As₂O₈,Cu₄O（AsO₄）₂,Cu₄（As₂O₇）O₂。该方法工艺简单、无二次污染,为废渣的综合利用提供了一种新的技术路线。     

从废甲醇合成催化剂中回收铜锌

将废RK-05甲醇合成催化剂经过煅烧、浸取、精制等工序回收其中的铜和锌。经正交实验得到煅烧废催化剂的最优工艺参数为:废催化剂筛目100目,煅烧温度950℃,煅烧时间60 min。最佳浸取工艺条件为:废催化剂加入量约4 g/L,浸取温度75℃,浸取剂用量与理论用量体积比2.0~3.0,浸取剂浓度4.0 mol/L,浸取时间10min。精制工序制备CuO的最佳工艺条件为:锌粒与滤渣质量比为1.00,反应时间3 h,煅烧温度450℃,煅烧时间4 h。制备ZnO的最佳工艺条件为:煅烧温度800℃,煅烧时间60 min。回收的产品CuO纯度为99.1%,满足GB/T674—2003《化学试剂粉状氧化铜》中优级品的标准。回收的产品ZnO纯度为99.6%,满足GB/T3185—1992《氧化锌(间接法)》中一级品的标准。