Metal Resources Research Articles

Iron-gelatin aerogel derivative as high-performance oxygen reduction reaction electrocatalysts in microbial fuel cells

Currently, precious based materials are known as highly efficient and widely used catalysts for oxygen reduction reaction (ORR). The expensive price and scarce resource of precious metals have stimulated researchers to explore low-cost and high-performance non-precious metal catalysts. Gelatin is a promising precursor to prepare cost-effective and high-performance catalysts because of abundant micropores and nitrogen self-doping sites after pyrolysis. Herein, we developed a new highly active ORR catalyst (G/C–Fe-2) containing Fe–N coordination sites and Fe/Fe3C nanoparticles. G/C–Fe-2 exhibited excellent ORR electrocatalytic activity (onset potential: 0.21 V, and limiting current density:7.36 mA cm−2) and high-performance in air-cathode MFCs (Output voltage: 660 mV, and maximum power density: 560 mW m−2). It is significant for synthesizing low-cost and high-activity ORR electrocatalysts through this strategy.

Extraction of valuable metals from acidic wastewater and blast furnace slag by a collaborative utilization process

AbstractTwo typical wastes, acidic wastewater and titanium‐bearing blast furnace slag, are generated in the smelting process of vanadium‐titanium magnetite. Generally, the acidic wastewater is neutralized by lime or limestone and titanium‐bearing blast furnace slag is directly stacked in the tailings pond, which not only pollutes the ecological environment but also causes the waste of metal resources. In this study, a collaborative utilization process for efficient extraction of titanium, iron, magnesium, and aluminum from acidic wastewater and low titanium‐bearing blast furnace (LTBBF) slag was proposed. At the leaching temperature of 80°C, the leaching time of 50 min, and the liquid–solid ratio of 9:1, 99.26% Ti, 99.47% Mg, and 99.45% Al could be extracted from LTBBF slag by acidic wastewater. Leaching residue mainly composed of Ca and Si could be used as silicon fertilizer. The Ti in the leaching solution could be separated by adding Na3PO4. The precipitation efficiency of Ti reached 98.53% under the molar ratio of Na3PO4 to TiO2 of 1.4, reaction temperature of 85°C, and reaction time of 40 min. The titanium phosphate ((TiO)2P2O7) was obtained by calcination of the precipitate at 900°C for 3 h. Adding oxalic acid to the filtrate above, the precipitation efficiency of Fe, Mg, and Mn reached 96.47%, 99.21%, and 99.45%, respectively, under the optimal conditions, while the precipitation efficiency of Al was only .38%. By adjusting the pH of the filtrate to 6.5, 99.83% Al could be precipitated as Al(OH)3, and the final solution was evaporated to obtain Na2SO4 products. The method proposed realizes the harmless treatment of acidic wastewater and LTBBF slag and recovers the metal resources in both of them.

Environmental impact assessment of second life and recycling for LiFePO4 power batteries in China

The number of spent lithium-ion batteries (LIBs) will increase exponentially in the coming decade with the retirement of electric vehicles (EVs). There is a knowledge gap in assessing the environmental impact of different terminal disposal paths for EV LIBs in China. Here, we take representative lithium iron phosphate (LFP) power batteries as example and carry out a bottom-up life cycle assessment (LCA). The life cycle stages of battery manufacturing, use, second life and battery recycling are considered to conduct a cradle-to-grave environmental impact analysis. To investigate the environmental benefits of end-of-life (EoL) stage for LFP batteries, two EoL management scenarios are considered in this study. The first one combines second life application with battery recycling, and the second recycles the retired batteries directly after EV use. The result shows that the secondary application of retired LFP batteries in energy storage systems (ESSs) can effectively reduce the net environmental impact of LIB life cycle, especially for fossil fuel depletion. When the service life of secondary use is increased from 1 year to 10 years, the environmental benefits of different impact categories will increase by 0.24–4.62 times. For direct recycle scenario, recycling retired LFP batteries can save more than 30% of metal resources. By comparison, we find that recycling lithium nickel manganese cobalt oxide (NCM) batteries has greater environmental benefits than recycling LFP batteries for all impact categories. When considering the environmental benefits at the EoL stage, most life cycle environmental impact is likely to be offset or even show positive benefits if more than 50% of power batteries can be reused in ESSs after retirement.

Prediction of China's copper material flows under carbon emissions projections for the shared socioeconomic pathways

The production and utilization of metal resources are a major source of carbon emissions and will be constrained by future carbon peaking and carbon neutrality. Based on carbon emissions scenarios of Shared Socioeconomic Pathways (SSP1–5), we performed a life cycle assessment and material flow analysis to analyze future domestic copper production and utilization under the constraint of CO2 budgets in China. Our findings indicates that secondary copper has potential to substitute primary copper as a major component of copper production in the future. Copper in-use stock shows a peaking trend, while the flow intensity is projected to show an overall decreasing trend, indicating the beginning of a transitional period relating to economic growth and copper utilization. Meanwhile, the increase of recovery level shows contributions to copper production. Conclusions above suggest the importance of active resource recovery and the decoupling of metal production from economic activities.

Scientific analysis and research on the Warring States bronze mirrors unearthed from Changsha Chu cemetery, Hunan province, China

AbstractChangsha is one of the densest areas where Warring States bronze mirrors have been unearthed in mainland China. This article first conducts a systematic scientific analysis and research on the Warring States bronze mirrors unearthed from Changsha Chu cemetery. The chemical composition analysis data of 23 bronze mirrors show that most of the bronze mirrors are Cu‐Sn‐Pb ternary alloy, and the bronze mirrors containing metal bodies are mainly high Sn Sn‐Pb bronze. The metallographic microstructures of four bronze mirrors are all high Sn Sn‐Pb bronze casting structures. The results of Pb isotope ratio analysis show that the Pb isotope data of all bronze mirrors conform to the characteristics of common Pb, and their distribution can be divided into three groups. Most of the Pb materials used in bronze mirrors probably come from local mines in Hunan. This fully reveals the importance of Hunan's local metal resources in the production activities of Changsha Chu mirrors. Combining the results of Pb isotope research and related archaeological data, Changsha should be one of the most developed regions in the mirror casting industry of the Chu State during the Warring States period, and it plays a significant role in the bronze production system and metal resource circulation network of the Chu State.

Assessment of bauxite residue as secondary resource for rare earth metal and valorization challenges: A perspective

Bauxite residue (BR), simultaneously an environmental challenge as well as known to be a secondary resource for resources various valuable metals like Ti, V, Ga, and rare earth metal (REM). Lack of understanding and technology detects BR to be stockpiled which is counterproductive considering the environment, land scarcity, and management of BR inventories. As BR remains unexploited, significant amounts of REMs in BR remain unlocked, which are critical metals from green energy, environmental sustainability, and supply chain bottleneck perspective. Our current investigation analyses the potential of BR as secondary resources and quantity and worth of REM being remains unlocked. The quantitative content of global bauxite, alumina, and BR production during the last 5 decades have been analyzed. Also, plausible BR generation in the next 3 decades has been estimated. Considering the content of REM in BR amount of REM either stockpiled or to be stockpiled along with BR has been analyzed. Our study indicated about 9.14 million tons of REM remain locked in the stockpiled BR, 31.24 million tons of REM remain locked in the bauxite reserve. The worth of worldwide REM oxide remains unexploited in bauxite reserves and locked in stockpiled BR could be approximately $5000 billion, potentially can meet current and project demand of REM abundantly.

Carbonized resin with Fe&Co bimetal for peroxymonosulfate activation to degrade atrazine

Aiming at realizing heavy metal recycling and resource utilization, a carbon-based bimetallic material (Fe1Co2@C) was fabricated via calcining cationic resin exchanged with Fe and Co cations. It exhibited superior peroxymonosulfate (PMS) activation performance to degrade atrazine (ATZ) compared with the monometallic materials (Fe@C and Co@C). Fe1Co2@C/PMS performed high degradation of 5 mg/L ATZ with the reaction rate constant (kobs) of 0.0869 min−1 within 30 min of reaction time. The effects of catalyst loading, PMS dosage, initial pH, and the presence of inorganic ions (NO3−, SO42− Cl−, and HCO3−) and natural organic matters (NOMs) were also investigated in this work. According to the radical quenching experiments and electron paramagnetic resonance (EPR), hydroxyl radical (•OH) and sulfate radical (SO4•−) were identified to be the primary reactive oxygen species (ROS) responsible for the ATZ degradation, especially •OH. What’s more, reaction mechanism of Fe1Co2@C was demonstrated that −(C− SO3)x − Co(II) and the synergy between Fe and Co on the surface could both promote the heterogeneous redox cycles of Co(II)/Co(III) and Fe(II)/Fe(III) to activate PMS. Based on the detection results of intermediates by LC-MS, possible degradation pathways of ATZ included dealkylation, dichlorination, hydroxylation, and deamination-hydroxylation processes were proposed. This research not only provides new insights of PMS activation by carbon-based bimetallic catalyst for water treatment, but also proposes a new way for reusing the waste saturated cation resin waste with heavy metal.

Deep purification of copper from Cu(II)-EDTA acidic wastewater by Fe(III) replacement/diethyldithiocarbamate precipitation

Cu(II)-EDTA is a highly stable typical metal-organic complex in a wide pH range (3.0–12.0) and it is difficult to deeply purify Cu(II) by conventional precipitation methods. In this study, Fe(III) replacement/diethyldithiocarbamate (DDTC) precipitation combined process is proposed as a promising strategy to achieve the deep purification of Cu(II) from Cu(II)-EDTA acidic wastewater. The underlying mechanism has also been systematically elucidated by chemical equilibriums, experiments, and density functional theory (DFT) calculations, laying a foundation for the development and application. Chemical equilibriums show that Fe(III) replacement favors the stoichiometric release of Cu(II) from Cu(II)-EDTA and the formation of Fe(III)-EDTA complex under acidic conditions. Experimentally, Cu(II) is removed (over 99.99%) and deeply purified (under 0.008 mg/L) under the optimal conditions, which is lower than the most stringent discharge standards of copper ions in electroplating effluent (<0.5 mg/L, China). DFT calculations reveal that DDTC could further precipitate the released free copper ions via the carbon disulfide (–C(=S)–S) chelating group while exhibiting a slight effect on the Fe(III) in Fe(III)-EDTA. Considering these results, the electronic structures of Cu(II) and Fe(III), as well as their interaction with EDTA and DDTC ligands, are discussed to understand the mechanism of Fe(III)/DDTC process. By introducing a low dosage of Fe(III), the DDTC could efficiently purify Cu(II) from the Cu(II)-EDTA acid wastewater and realize the near-zero discharge of metal pollutants in metal-organic complex wastewater. It is believed that the main findings may benefit the water pollution reduction and comprehensive recycling of metal resources.

Bacterial cellulose hybrid membrane grafted with high ratio of adipic dihydrazide for highly efficient and selective recovery of gold from e-waste

To solve metal resource shortage and alleviate environmental issues, it is in urgent need to explore cost-effective and environment-friendly adsorbents for sustainable recovery of valuable gold from e-waste. Herein, bacterial cellulose (BC) hybrid membrane grafted with adipic dihydrazide (ADH) has been fabricated via a facile schiff base reaction strategy for efficient and selective recovery of gold from complex aqueous media. The resulting ADH@BC hybrid membrane features high ratio of hydrazide groups (67% of ADH by mass content) and hierarchical porous structure, ensuring high adsorption capacity (1149 mg/g) and fast adsorption equilibrium time (20 min) toward gold. Meanwhile, the remarkable recovery selectivity of gold is achieved in the simulated e-waste leachate containing a large amount of interfering metal ions. Notably, the captured Au(III) species on ADH@BC hybrid membrane can be directly converted by redox-active hydrazide groups into Au(0) with no need of any external reductant. Furthermore, the developed ADH@BC membrane possesses superior recycling and reusability performance, as reflected by no obvious decrease in gold extraction capability after six cycles. More importantly, the ADH@BC hybrid membrane is capable of extracting almost 100% of gold from actual waste central processing unit (CPU) leachate, yielding high-purity gold (23.7 K) after pyrolysis.

Mineralogical Characteristic and Beneficiation Evaluation of a Ta-Nb-Li-Rb Deposit

In order to rationally develop and utilize a Ta–Nb–Li–Rb rare metal deposit in Jiangxi Province, the mineralogical characteristics of the ore, such as chemical composition, mineral composition, modes of occurrence of major elements, and dissemination characteristics of major minerals, were investigated in detail based on optical microscopy analysis, chemical analysis, X-ray diffraction analysis, artificial panning, mineral liberation analysis, and electron probe microanalysis. The results reveal that the main useful elements in the ore are tantalum, niobium, lithium, and rubidium. Niobium and tantalum are mainly found in the mineral form of columbite. Columbite has particle sizes ranging from 0.5 mm to 0.012 mm, with the most common sizes being 0.3 to 0.044 mm. Intergranular dispersion accounts for 73.92% of the embedding in columbite, whereas inclusions account for 26.08%. Lithium is found mostly in zinnwaldite, while rubidium is found primarily in feldspar and zinnwaldite, both in a homogenous distribution. The beneficiation evaluation of this ore was conducted based on the mineralogical characteristic, and it indicates that the tantalum-niobium–lithium–rubidium rare metal resources, as well as the feldspar and quartz non-metallic resources in the ore, can be effectively and comprehensively recovered using gravity, magnetic, and flotation separation methods. A staged grinding and separating process was adopted which could produce tantalum–niobium mineral concentrates (18.34% Ta2O5 at a recovery of 47.65% and 41.33% Nb2O5 at a recovery of 69.96%), zinnwaldite concentrate (2.41% Li2O and 0.80% Rb2O at a recovery of 81.82%) and other concentrates such as cassiterite, topaz, galena, sphalerite, and feldspar. This study provides suggestions for the rational development and utilization of the deposit and provides a reasonable level of recovery prediction.

Selective adsorption of anions on hydrotalcite-like compounds derived from drinking water treatment residuals

Most drinking water treatment residuals (DWTRs) with rich metal resources are landfilled directly without treatment, which results in wasted Al/Fe resources. This work proposes a new method of preparing Mg–Al–Fe Hydrotalcite-like compounds (MAF-HTCLs) by recycling DWTRs as the raw material to selectively adsorb anions in the waste water. In this study, MAF-HTCLs were prepared by the coprecipitation method with recycled DWTRs. The characterizations and adsorption of MAF-HTCLs were studied for the selective adsorption of P, Cr, F, and Br. The adsorption capacity was increasing as the value of pH decreased. For kinetic adsorption, the pseudo-second-order model fit better, and two isotherm models (the Langmuir and Freundlich models) described the isotherm results well. According to the Langmuir model, the maximum adsorption capacities of P, Cr, F, and Br were 55.2, 34.9, 16.84, and 13.9 mg/g, respectively. Based on the results of characterizations before and after adsorption, adsorption mechanisms of Cr, F, and Br were proposed, including physicochemical adsorption, surface complexation, and ion exchange, in which ion exchange was dominant. Finally, we determined that the selective adsorption mechanisms of P on MAF-HTCLs included strong ion exchange and surface chemical precipitation by analyzing the results of X-ray photoelectron spectroscopy.

The potential for copper slag waste as a resource for a circular economy: A review – Part I

• Potential for copper slag waste as global resource for circular economy is examined. • Comprehensive review given of amount generated in the last 20 years worldwide. • Assessed is the global demand and supply risks for copper and cobalt. • Estimated are production rate and remaining reserves and benefits of reprocessing. The mining industry faces a number of challenges that include rapid depletion of high-grade deposits, high energy cost for metal production, and growing environmental concerns associated with mining waste disposal. Copper slag is one of the mining wastes that is raising growing concern due to the huge volumes being produced and dumped annually worldwide. These huge quantities of slag not only cause environmental pollution and space problems for disposal, but they also waste valuable copper and cobalt. This is increasingly important due to the growing demand for these metals in emerging technologies, potentially resulting in a supply deficit from conventional mining production. To address these challenges, recycling and repurposing of copper slag waste using innovative technologies should be considered, creating a resource for a circular economy. This paper presents a review of copper slag production and its potential as a world resource for cobalt and copper metals. An overview of copper and cobalt production from ore reserves, and of global demand and supply risks for these metals is presented. The potential benefits of reprocessing copper slag waste using the circular economy model are discussed. This paper demonstrates that applying the circular economy principles to the copper slag waste has the potential to create additional economic value, improve the energy efficiency of the metal production, increase the supply of critical metals, and reduce the impacts of metal production on the environment.

120\xa0years of georesources research in Switzerland: the Swiss Geotechnical Commission (1899\u20132018)

Geological surveys have a wide range of tasks for their countries: to map the geology and to assess the georesources potential for metallic ores, industrial minerals, geothermal energy, fossil fuels, aggregates and groundwater. In Europe, most countries founded geological surveys around the mid-nineteenth century in order to create an overview of the geological resources they wanted to exploit. In Switzerland, at that time, the industrial revolution triggered a tremendous demand for infrastructure and energy raw materials. However, no national georesources institution was established when the nation-forming process among the 25 cantons culminated in the foundation of the Swiss Federal State in 1848. The Swiss Geological Survey was founded 138 years later in 1986. How did Switzerland map the country, assess the resource potential and provide fundamental data for land use planning without such an organisation? This paper elaborates on the evolution of Swiss institutions mandated to study the geological resources, with a focus on the Swiss Geotechnical Commission (SGTK, 1899–2018). Given the low financial resources, no long-term nation-wide investigation programs could be implemented. The commission's study program was mainly driven by external societal and political factors. World War I for example reactivated the search for coal which was intensively exploited during those years. Before and during World War II, the focus temporarily shifted to oil and gas exploration. From 1970 onwards, SGTK was involved in several applied research projects and collaborations with various industry partners. In this paper, we revisit the key turning points in the evolution of the commission's investigation program, including related financial and organisational aspects, and discuss how Switzerland’s federalistic structure influenced the geological survey activities. The history of the SGTK represents an exemplification of how a nation managed its geological survey activities, until 1986 in the absence of a geological survey and without large hydrocarbon and metallic ore resources and a corresponding, significant mining industry. The SGTK case also shows that flexible, project-based investigations can be advantageous as they respond to current challenges at short notice. This could to some degree substitute the initial absence of a geological survey, as shown by the numerous SGTK monographs that are key references also 100 years after their publication.

Regeneration of high-performance Li1.2Mn0.54Ni0.13Co0.13O2 cathode material from mixed spent lithium-ion batteries through selective ammonia leaching

The efficient recycling process of spent lithium-ion batteries (LIBs) to regenerate electrode materials can alleviate the metal resources scarcity and environmental pollution. Here, the Li-rich cathode Li1.2Mn0.54Ni0.13Co0.13O2 (LR) material was successfully re-synthesized via an environment-friendly and impurity-free recycling process combined ammonia leaching with sol-gel process. Compared with the general methods, ammonia leaching is delicately applied to selectively extract valuable metals from spent LiNixCoyMnzO2 materials exclusive of other impurities (Fe, Al). The process facilitates the subsequent recovery without additional purification process. Surprisingly, the leaching efficiency of Li, Ni, and Co elements is up to as high as 99.28%, 99.63%, and 99.76%, respectively. After adding extra metal compounds stoichiometrically, LR with uniform particle size and elements distribution was regenerated from the valuable metals in the lixivium via the sol-gel method. The LR synthesized at 800 °C exhibits a satisfying capacity of 246.5 mAh g−1 at 0.1 C and high-stable cycle performance with a capacity of 163.3 mAh g−1 after 80 cycles at 0.2 C between 2.0 and 4.8 V. The fundamental results provide inspiration for recovery of the complex spent LIBs, which can selectively separate the multiple metal impurities with high-efficient reutilization.

Catalysing electrowinning of copper from E-waste: A critical review

Smart technologies and digitalisation have increased the consumption of scarce metals that threaten the sustainability of intricated industries. Additionally, the growing streams of waste electrical and electronic equipment (e-waste) are significant hazards to public health and the environment. Thus, there is an escalating need to recover metals from e-waste for sustainable management of metal resources. Hydrometallurgical processing of e-waste, involving copper (Cu) leaching and its subsequent recovery from pregnant leach solution (PLS) via electrowinning, has emerged as an efficient strategy to close the recycling loop. Electrowinning from PLS demonstrated higher Cu recovery efficiency and operational feasibility with a lower reagent use and lesser waste generation. Nevertheless, multiple issues challenged its practical implementation, including selective recovery of Cu from PLS containing mixed metals and high energy consumption. This review (1) identifies the factors affecting Cu electrowinning from PLS; (2) evaluates the composition of lixiviants influencing Cu electrowinning; (3) appraises various catalysts developed for enhancing Cu electrodeposition; and (4) reviews coupled systems that minimised process energy consumption. From the literature review, electrocatalysts are prospective candidates for improving Cu electrowinning as they reduced the cathodic reduction overpotentials, enhanced surface reaction kinetics and increased current efficiency. Other catalysts, including bioelectrocatalysts and photoelectrocatalysts, are applicable for dilute electrolytes with further investigations required to validate their feasibility. The coupled systems, including slurry electrolysis, bioelectrochemical systems and coupled redox fuel cells, minimise process energy requirements by systematically coupling the cathodic reduction reaction with suitable anodic oxidation reactions having thermodynamically low overpotentials. Among these systems, slurry electrolysis utilising a single-step processing of e-waste is feasible for commericalisation though operational challenges must be addressed to improve its sustainability. The other systems require further studies to improve their scalability. It provides an important direction for energy-efficient Cu electrowinning from PLS, ultimately promoting a circular economy for the scarce metal resources.

Bio-capture of Cr(VI) in a denitrification system: Electron competition, long-term performance, and microbial community evolution

Chromium is widely applied in industries as an important metal resource, but the discharge of Cr(VI) containing wastewater leads to the loss of chromium resources. This study proposed a bio-capture process of chromium in a denitrification system. The bio-capture potentiality was explored by investigating the electron competition between Cr(VI) and nitrogen compounds reduction, the long-term bio-capture performance, and the microbial community evolution. In the competition utilization of electron donors, both NO3--N and NO2--N took precedence over Cr(VI), and NO2--N reduction was proved to be the rate-limiting step. Under the optimum conditions of 20 mg/L NO3--N and 6 h HRT, 99.95% of 30 mg/L Cr(VI) could be reduced, and 220980 μg Cr/g MLSS was captured by the biofilm, which was fixed in intercellular as Cr(III). Microbiological analysis confirmed that the bio-reduction of Cr(VI) and NO3--N was mediated by synergistic interactions of a series of dominant bacteria, including genera Acidovorax, Thermomonas, and Microbacterium, which contained both the denitrification genes (narG, narZ, nxrA, and nirK) and chromate reduction genes (chrA and chrR). This study proved the feasibility of chromium bio-capture in denitrification systems and provided a new perspective for the Cr(VI) pollution treatment.

Comparation on the methods of removing impurity metals from copper powder of waste printed circuit boards

Copper powder of waste printed circuit boards (WPCBs), an important secondary metal resource, is usually processed by copper concentrate pyrometallurgy system to recover valuable metals. However, metals such as Pb, Sn, Zn and Al in copper powder of WPCBs are harmful to copper smelting system. Therefore, a two-stage leaching process was proposed to remove impurity metals from copper powder, and different routes were screened. Copper powder was firstly leached in the hydrochloric acid to remove Al, and then the Al-removed residue was treated to recover Sn and Pb by two routes, i.e., acid oxidation leaching or alkaline pressure oxidation leaching, respectively. The results showed that more than 97.15% of Al in copper powder was removed by the hydrochloric acid leaching. In HCl system adding H2O2, the leaching ratios of Pb and Sn reached 91.07% and 94.67%, respectively. In the alkaline pressure oxidation leaching system, the leaching ratios of Pb and Sn were 86.63% and 93.80%, respectively. In general, the separation and recovery of valuable metal resources in the WPCB copper powder were realized, and Cu was further enriched, providing high-quality raw materials for copper pyrometallurgy.

Recovery of Lithium Iron Phosphate by Specific Ultrasonic Cavitation Parameters

With the widespread use of lithium iron phosphate batteries in various industries, the amount of waste lithium iron phosphate batteries is also increasing year by year, and if not disposed of in a timely manner, will pollute the environment and waste a lot of metal resources. In the composition of lithium iron phosphate batteries, the cathode has an abundance of elements. The ultrasonic method is a crucial method to recover waste LiFePO4 batteries. It has the following disadvantages, such as the lack of empirical parameters and suitable research equipment. In order to overcome the inefficiency of the LiFePO4 recycling method, the airborne bubble dynamical mechanism of ultrasound in the removal of lithium phosphate cathode material was studied by a high-speed photographic observation and Fluent simulation and the disengagement process. Mainly aimed at the parameters such as action time, power, frequency, and action position in the detachment process were optimized. The recovery efficiency of lithium iron phosphate reached 77.7%, and the recovered lithium iron phosphate powder has good electrochemical properties, with the first charge–discharge ratio of up to 145 (mAh)/g. It is shown that the new disengagement process established in this study was adopted for the recovery of waste LiFePO4.

The Effect of Silicate Ions on the Separation of Lithium From Geothermal Fluid

In an enhanced geothermal system (EGS), geothermal energy in rocks with insufficient permeability or fluid saturation can be used by creating artificial geothermal reservoirs. Generally, EGS geothermal fluid contains high concentrations of total dissolved solids that originated from various geochemical reactions between the fluid in the reservoir and the minerals in the rock. For example, the concentration of lithium ions are measured approximately 150 mg/L, and several researchers have focused on the recovery of lithium in the geothermal fluid using various methods, one of which is liquid extraction. Solvent extraction has been used to recover lithium from various sources, and successful recovery efficiency have been attained. However, the geothermal fluid in EGS reservoirs contains high concentrations of SiO2, which might inhibit the selective recovery of lithium. Thus, in this study, two consecutive stages of solvent extraction were used to separate the lithium from the geothermal fluid that contained different concentrations of SiO2 ions. The divalent ions were removed in the first stage, and the lithium ions were extracted effectively in the second stage. The SiO2 inhibits the selective recovery of lithium in the first stage to a greater extent than it does in the second stage. The spectroscopy data shows a decrease of the organic solvents main functional group (P=O &amp;amp; P-O-H) absorbance that reacts with the metal ions of the geothermal water after extraction however the intensity difference was reduced as the SiO2 concentrations increases. Silicate ions can be problematic due to the formation of scaling in EGSs, so controlling its concentration in the geothermal reservoir would be beneficial for the long-term operation of EGSs and for the successful recovery of valuable metal resources from EGS reservoirs.

Progresses in Sustainable Recycling Technology of Spent Lithium‐Ion Batteries

The number of lithium‐ion batteries (LIBs) is steadily increasing in order to meet the ever‐growing demand for sustainable energy and a high quality of life for humankind. At the same time, the resulting large number of LIB waste certainly poses safety hazards if it is not properly disposed of and will seriously harm the environment due to its inherent toxicity due to the use of toxic substances. Moreover, the consumption of many scarce precious metal resources is behind the mass production of batteries. In the light of severe environmental, resources, safety and recycling problems, recycling spent LIBs have become an essential urgently needed action to achieve sustainable social development. This review therefore critically analyses the value and the need for recycling of spent LIBs from a variety of resources and the environment. A range of existing technologies for recycling and reusing spent LIBs, such as pretreatment, pyrometallurgy, hydrometallurgy, and direct recycled methods, is subsequently summarized exclusively. In addition, the benefits and problems of the methods described above are analyzed in detail. It also introduces recycling progress of other LIB components, such as anodes, separators, and electrolytes, as well as the high‐value cathode. Finally, the prospects for recycling LIBs are addressed in four ways (government, users, battery manufacturers, and recyclers). This review should contribute to the development of the recycling of used LIBs, particularly in support of industrialization and recycling processes.