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Copper leaching from waste electric cables by biohydrometallurgy
Abstract
This study examines the leaching of copper from waste electric cables by chemical leaching and leaching catalysed by Acidithiobacillus ferrooxidans in terms of leaching kinetics and reagents consumption. Operational parameters such as the nature of the oxidant (Fe3+, O2), the initial ferric iron concentration (0–10 g/L) and the temperature (21–50 °C) were identified to have an important influence on the degree of copper solubilisation. At optimal process conditions, copper extraction above 90% was achieved in both leaching systems, with a leaching duration of 1 day. The bacterial leaching system slightly outperformed the chemical one but the positive effect of regeneration of Fe3+ was limited. It appears that the Fe2+ bio-oxidation is not sufficiently optimised. Best results in terms of copper solubilisation kinetics were obtained for the abiotic test at 50 °C and for the biotic test at 35 °C. Moreover, the study showed that in same operating conditions, a lower acid consumption was recorded for the biotic test than for the abiotic test.
... To minimise continuous addition of acid during the bioleaching of metals from PCBs to keep the pH below 2, Bryan et al. [16] investigated the addition of pyrite as its leaching and the associated sulfur oxidation results in in-situ generation of acid, while also supplementing Fe available in solution. Lambert et al. [9] showed that the rate of copper extraction from electric cables is dependent on the concentration of the available Fe 3þ , such that leaching kinetics are enhanced with increasing ferric iron concentration. ...
... This has been reported for the bioleaching of PCBs, WEEE and sulfide minerals [16e21]. Inhibition in microbial ferrous iron oxidation can be caused by metals such as Fe 2þ (substrate) [22,23], Fe 3þ (product) [18,22], as well as other base metal ions such as Zn 2þ , Cu 2þ , Al 2þ , Ni 2þ -as individual metal ions or in their combination [9,16,23e25]; as well as components liberated from PCBs [9,12,13,16,21,26] and other forms of e-waste such as plastic [9]. Kachatryan et al. [18] investigated the effect of Fe 2þ and Fe 3þ ions on the growth and Fe 2þ oxidation kinetics of L. ferriphilum, reporting that Fe 2þ oxidation was competitively inhibited at concentrations between 4 g/L Fe 3þ and 11.2 g/L Fe 3þ . ...
... This has been reported for the bioleaching of PCBs, WEEE and sulfide minerals [16e21]. Inhibition in microbial ferrous iron oxidation can be caused by metals such as Fe 2þ (substrate) [22,23], Fe 3þ (product) [18,22], as well as other base metal ions such as Zn 2þ , Cu 2þ , Al 2þ , Ni 2þ -as individual metal ions or in their combination [9,16,23e25]; as well as components liberated from PCBs [9,12,13,16,21,26] and other forms of e-waste such as plastic [9]. Kachatryan et al. [18] investigated the effect of Fe 2þ and Fe 3þ ions on the growth and Fe 2þ oxidation kinetics of L. ferriphilum, reporting that Fe 2þ oxidation was competitively inhibited at concentrations between 4 g/L Fe 3þ and 11.2 g/L Fe 3þ . ...
... Thus, there is a requirement to develop eco-friendly treatments, which are intended to increase the sustainability of recovery processes [3]. Consequently, studies' interests are moving towards biohydrometallurgical processes as an alternative promising for recovering metals from PBCs [8,[11][12][13][14]. ...
... Mechanical [6], pyrometallurgical [1], hydrometallurgical [7], and biohydrometallurgical processes can be used to extract metals from PCBs [8,9]. During the recovery process of electronic waste, the mechanical processes are applied as pre-processing, aiming to ...
In this work, a biological recovery of metals (copper and gold) from computer printed circuit board (PCB) waste was carried out by bioleaching using Aspergillus niger. Three bioleaching methods comprising one or two steps or using spent medium were tested in an incubator shaker at 30 °C and 160 rpm with different PCB waste concentrations (2.5 to 10 g/L). Glucose was used as the carbon source. The best condition evaluated was carried out in a stirred tank reactor. The FTIR spectrum confirmed the presence of oxalic, citric, and gluconic acids. A. niger showed an efficiency of bioleaching of up to 100% and 42.5% for copper and gold, respectively, using the two-step method with 2.5 g/L PCB waste after 14 days of the process. The efficiency of bioleaching in a stirred tank reactor was 83% for copper and 24% for gold. The mean metallic particle size obtained after bioleaching varied according to the PCB waste concentration (2.5–10 g/L) added in the experiments. A transmission electron microscope analysis confirmed the synthesis of metallic nanoparticles with spherical morphology. The results indicated that the PCBs bioleaching process with A. niger can be an environmentally friendly alternative to current mechanical and metallurgical processes for metal leaching.
... Fe 3+ was therefore concluded to be the main oxidant responsible for copper leaching (Lambert et al., 2015;Wu et al., 2018). In the absence of microorganisms, biogenic Fe 3+ sample rendered a copper removal of 90.1 ± 3.2 mg cm − 2 after 3 h. ...
... This result was improved in the 9 K biotic system as the total Cu amount leached achieved a value of 102.3 ± 5.9 mg cm − 2 , with the bacterial effect being similar (↑13.5 %) to those described in previous studies (Díaz-Tena et al., 2016;Yang et al., 2017). On the other hand, Lambert et al. (2015) reported that this difference remained below 10 % during the first 10 h in assays performed with a copper-adapted culture containing A. ferrooxidans (prevalent specie), L. ferrooxidans and A. thiooxidans and an initial ferric iron concentration of up to 7 g Fe 3+ L − 1 (82-100 % of total iron). The positive effect of the bacterial presence was even lower for Xenofontos et al. (2015), who observed a limited increase (<1 mg cm − 2 ) in the same operation period (3 h) by means of a A. ferrooxidans strain withdrawn from a pregnant leach solution and an Fe 3+ concentration of 6.5 g L − 1 (Xenofontos et al., 2015). ...
Bacterially assisted leaching has been proposed for many innovative applications, such as urban mining or micromachining, but many technical challenges including substrate toxicity and downstream processing of the leach liquor must be solved before its industrial implementation. This study was conducted with the final goal of improving the average specific metal removal rate (SMRR) and reducing the amount of depleted solution generated in the leaching process of copper workpieces, with special attention paid to the detection of microbial activity inhibition.
The copper leaching rate is almost entirely dependent upon the Fe3+ concentration with Fe3+/Fe2+ ratios higher than 0.3, after which A. ferrooxidans oxidation action becomes relevant. In both biotic and abiotic experiments, the SMRR peaked after the first hour of treatment, and it decreased sharply after three hours. A consecutive process alternating bioleaching and oxidant regeneration stages was proposed to improve performance, which considerably reduced both the time needed to dissolve a certain amount of metal and waste generation. The decrease in copper removal (25 %) and the increase in the time required for oxidant regeneration after five leaching cycles (longer than 90 h) were attributed to bacterial inhibition in the presence of 10.7 g Cu2+ L−1, which was established as the limiting metal concentration for reusing the biologically active solution.
... Higher temperatures enable faster kinetic reactions in chemical system [29]. In order to study the extraction of copper from the COBL ore at different temperatures, the COBL ore agitation leaching experiments were performed at 20 °C , 40 °C , 60 °C , and 80 °C . ...
... Higher temperatures enable faster kinetic reactions in chemical system [29]. In order to study the extraction of copper from the COBL ore at different temperatures, the COBL ore agitation leaching experiments were performed at 20 • C, 40 • C, 60 • C, and 80 • C. The concentration of sulfuric acid was 300 kg/t (3.06 mol/L), the liquid to solid ratio (vol/wt) was 3:1, and the leaching time was 4 h. ...
The reserve of the copper-oxide-bearing limonite ore (COBL ore) in Yulong Copper Co., Ltd. is up to 20 million tons with 1.79% of copper content. The characters of the copper resources in the COBL ore are high-proportioned oxidation state (99.98%) and combined state (84.83%). The combined copper oxide is mainly copper-oxide-bearing limonite, which has a copper content of more than 78%. Because of the high altitude and average annual temperature of 15 °C in Tibet, fire leaching cannot be adopted. The leaching efficiency of copper from COBL ore using direct leaching of sulfuric acid is only 40%, which is greatly influenced by temperature and time. Based on the characteristics of COBL ore, a novel combined method of magnetic separation and individual leaching has been proposed to efficient recover copper resources. Experimental results show that the magnetic concentrates and tailings were obtained by magnetic separation of COBL ore at 0.6 T with the yields were 59.65% and 40.35%, respectively. Due to the obvious leaching properties difference of the magnetic concentrates and tailings, individual leaching process routes were used to treat them. The magnetic concentrate was leached with stirring for 3 days at room temperature (20 °C), and the magnetic tailing was easily leached for 4 h at 40 °C. The recovery efficiency of total copper was 72%, which was about 32% higher than that of the single leaching of the COBL ore. The method proposed in this study achieves environmentally friendly, low energy consumption, and efficient extraction of refractory copper oxide ore.
... Of gold as the cyanide complex. Lambert et al., 2015 Temperature Temperature significantly influence the rate of reactions in coupled with the microbial growth rate albeit it also depends on the types of microorganisms applied (mesophiles/moderate thermophiles/thermophiles). ...
... A. ferrooxidans resulted in bioleaching efficiency of 90% Cu in 30 h at an elevated temperature 50°C, which required 137 h of bioleaching conducted at a lower temperature of 21°C. Lambert et al., 2015 Temperature significantly influence the biosynthesis of HCN with different bacterium. A higher HCN synthesis was observed at 25°C while using P. chlororaphis and C. violaceum. ...
This study has attempted to ascertain the linkages between circular bio-economy (CirBioeco) and recycling of electronic (e-)waste by applying microbial activities instead of the smelter and chemical technologies. To build the research hypothesis, the advances on biotechnology-driven recycling processes for metals extraction from e-waste has been analyzed briefly. Thereafter, based on the potential of microbial techniques and research hypothesis, the structural model has been tested for a significance level of 99%, which is supported by the corresponding standardization co-efficient values. A prediction model applied to determine the recycling impact on CirBioeco indicates to re-circulate 51,833 tons of copper and 58 tons of gold by 2030 for the production of virgin metals/raw-materials, while recycling rate of the accumulated e-waste remains to be 20%. This restoration volume of copper and gold through the microbial activities corresponds to mitigate 174 million kg CO2 emissions and 24 million m3 water consumption if compared with the primary production activities. The study potentially opens a new window for environmentally-friendly biotechnological recycling of e-waste under the umbrella concept of CirBioeco.
... Copper is the second most important nonferrous metal (after aluminum) and is being used in many industries ranging from healthcare to construction, machineries to electronics, and telecommunication [1]. Chalcopyrite (CuFeS 2 ) is the most predominant ore of copper and most often used as the raw material for the extraction of Cu. ...
... Almost 10%-15% of Cu is currently produced from secondary Cu resources such as alloys and scraps [3]. Of late, a lot of waste materials (metallurgical sludges, residues and slags, etc.) have been used for the extractive metallurgy of Cu [1,[6][7][8][9][10]. ...
Printed circuit boards (PCBs), a typical end-of-life electronic waste, were collected from an E-waste recycling company located in the Netherlands. Cu and precious metal concentration analyses of the powdered PCBs confirm that the PCBs are multimetallic in nature, rich, but contain high concentrations of Cu, Au, Ag, Pd, and Pt. Ferric sulfate concentration (100 mM), agitation speed (300 rpm), temperature (20 °C), and solid-to-liquid ratio (10 g·L⁻¹) were found to be the optimum conditions for the maximum leaching of Cu from PCBs. The ferric sulfate leachates were further examined for selective recovery of Cu as copper sulfides. The important process variables of sulfide precipitation, such as lixiviant concentration and sulfide dosage were investigated and optimized 100 ppm of ferric sulfate and (copper:sulfide) 1:3 molar ratio, respectively. Over 95% of the dissolved Cu (from the multimetallic leachates) was selectively precipitated as copper sulfide under optimum conditions. The characterization of the copper sulfide precipitates by SEM-EDS analyses showed that the precipitates mainly consist of Cu and S. PCBs can thus be seen as a potential secondary resource for copper.
... Bioleaching without the use of inorganic acids does not cause environmental pollution. Lambert et al. [54] found that the use of Acidithiobacillus ferrooxidans can promote the leaching kinetics of Cu, with the highest leaching rate reaching 90%. However, the bioleaching reaction time is relatively long and is not suitable for large-scale industrial production in general. ...
Copper plays a crucial role in the civilization of our lives. This review examines the flow of copper from the mining of ores to the end‐of‐life product, with particular emphasis on the recovery and re‐functionalization of copper and copper‐containing wastes. Beginning with the analysis of the global copper market, reserves, supply, and demand, a comprehensive account of the general copper recycling processes is presented, followed by the recycling of copper from traditional application fields such as power transmission, construction, and printed circuit boards, which contribute 10%–20% of the raw materials for annual refined copper products. Considering that copper is increasingly utilized in emerging fields such as batteries, catalysts, and biomedicine, the challenge of dealing with waste products from these sectors will become increasingly acute. This review not only explores and analyses the current state of copper recycling as a metal but also comprehensively investigates the areas of repair, reuse, and re‐functionalization of waste products, providing a theoretical basis and technical directions for the future development and transformation of the copper market.
... Lambert et al. [69] examine copper leaching from discarded electrical cables, comparing purely chemical leaching to Acidithiobacillus-catalyzed leaching in terms of kinetics and reagent needs. A higher efficiency in copper dissolution emerges under well-controlled redox conditions, aided by biologically regenerated ferric iron. ...
Heap leaching of copper is faced with a complex set of challenges, including mineral heterogeneity, the formation of passivating species, and the need to regulate critical variables such as pH, redox potential (Eh), oxidant concentration, and irrigation rate. If these factors are not properly managed, copper recovery is reduced, and significant environmental impacts may be generated, highlighting the urgency for systematic and sustainable approaches. To address this challenge, a systematic literature review (SLR) was conducted, screening 2344 documents and selecting 106 primary sources to analyze operational drivers and environmental considerations. Statistical methodologies (factorial designs, response surface methodology), multiscale modeling, and laboratory column tests were used to validate key variables, including pH (1.5–2.0), Eh (600–750 mV), temperature (25–55 °C), irrigation rate (5–15 L/(h·m2)), acid concentration (0.5–2.0 M), and emerging “green” reagents (e.g., glycine, organic surfactants). Precise control of these factors was found to reduce passivation, minimize fine-particle migration, and improve copper extraction up to 90%. The incorporation of oxidizing agents (e.g., Fe3+, H2O2) further accelerated mineral dissolution while preventing unwanted precipitates. In parallel, bioleaching strategies maintained high recoveries with lower chemical demand. Reviews of pilot studies confirmed the scalability of these optimized conditions, emphasizing both sustainability and cost-effectiveness.
... Bacterial leaching, also known as bioleaching, biohydro-metallurgy, or bio-oxidation of sulfides, can be defined as a natural dissolution process resulting from the action of a group of bacteria, mainly of the genus Thiobacillus, with the ability to oxidize sulfide SMMC, allowing the release of the metals contained in them [18,64]. ...
This review paper explores the potential of bioleaching as a sustainable alternative for recovering metals from solid matrices. With over 12 billion tons of solid waste annually worldwide, bioleaching provides a promising opportunity to extract metals from solid waste, avoiding harmful chemical processes. It explains bacterial and fungal bioleaching techniques that extract copper, gold, zinc, and other metals from solid matrices. Fungal bioleaching effectively extracts a wide range of valuable metals, including nickel, vanadium, aluminium, molybdenum, cobalt, iron, manganese, silver, platinum, and palladium. The review highlights different solid matrices with metal contents that have the potential to be recovered by bioleaching, presenting promising bioprocess alternatives to current industrially available technologies for metal recovery. The optimal conditions for bioleaching, including pH, temperature, agitation–aeration, and pulp density are also discussed. The review shows that bioleaching has the potential to play a crucial role in the transition to a more sustainable and circular economy by providing an efficient, cost-effective, and environmentally friendly method for metal recovery from solid matrices.
... Multi-step techniques are employed to recycle thin waste cables with diameters in the order of millimeters. These multistep techniques typically involve mechanical methods (such as the use of ultrasound [13] or hot-water processes [14] combined with a blender to disassemble the cables, followed by electrostatic separation [15,16], size classification [17], flotation [18 20], or dense medium separation [21] to separate the plastic and copper components), chemical methods (such as dissolution and cementation [22], chemical-or bio-leaching [23], and chloride volatilization [24]), and/or energy recovery processes (such as pyrolysis [25 28] and steam gasification [29]). ...
In this study, polyvinyl chloride (PVC) was pyrolyzed with sodium hydroxide (NaOH) to capture the generated hydrogen chloride (HCl) gas as sodium chloride (NaCl) and carbonize the organic contents to generate fuel gases such as hydrogen (H2) and methane (CH4). In addition, the pyrolysis behavior of PVC with NaOH, and its application to copper recovery from thin PVC-coated tinned copper multiwire cables were examined. With an increase in temperature, the PVC released HCl gas at approximately 300°C and underwent carbonization to generate fuel gases at approximately 500°C. Upon immersing the PVC in a NaOH solution, it was converted into a powdered carbonaceous material; therefore, the amount of HCl gas decreased by being captured as NaCl, whereas the amount of fuel gases generated increased by pyrolysis. At a heating temperature of 500°C, the PVC coating of the tinned copper wire was removed via the formation of a carbonaceous material and sodium salts after the addition of distilled water. The results suggest that this environmentally friendly and eff ective process for capturing HCl gas as NaCl and converting the covered PVC into carbonaceous materials and fuel gases is suitable for PVC treatment, and the proposed approach can be applied to copper recovery from multiwire tinned copper cables through pyrolysis with NaOH.
... It also encompasses appliances from the medical, automobile, sports, and toy sectors (Li et al. 2007;Chen et al. 2015). Different parts of electric and electronic equipment (EEE), like used batteries, electric wires, printed circuit boards (PCBs), plastic casings, cathode ray tubes (CRTs), poly(p-phenylene terephthalamide, activated glass, and lead capacitors, are also categorized as e-waste (Lambert et al. 2015;Ilankoon et al. 2018;Mazrouaa et al. 2019). The material design of EEE is very complex, as 69 elements from the periodic table can be found in EEE, including precious metals (like platinum, gold, rhodium, silver, copper, iridium, ruthenium, and osmium), Critical Raw Materials (CRM) (like indium, cobalt, bismuth, palladium, antimonyand germanium), and noncritical metals, such as iron and aluminum. ...
The electronic and electrical industrial sector is exponentially growing throughout the globe, and sometimes, these wastes are being disposed of and discarded with a faster rate in comparison to the past era due to technology advancements. As the application of electronic devices is increasing due to the digitalization of the world (IT sector, medical, domestic, etc.), a heap of discarded e-waste is also being generated. Per-capita e-waste generation is very high in developed countries as compared to developing countries. Expansion of the global population and advancement of technologies are mainly responsible to increase the e-waste volume in our surroundings. E-waste is responsible for environmental threats as it may contain dangerous and toxic substances like metals which may have harmful effects on the biodiversity and environment. Furthermore, the life span and types of e-waste determine their harmful effects on nature, and unscientific practices of their disposal may elevate the level of threats as observed in most developing countries like India, Nigeria, Pakistan, and China. In the present review paper, many possible approaches have been discussed for effective e-waste management, such as recycling, recovery of precious metals, adopting the concepts of circular economy, formulating relevant policies, and use of advance computational techniques. On the other hand, it may also provide potential secondary resources valuable/critical materials whose primary sources are at significant supply risk. Furthermore, the use of machine learning approaches can also be useful in the monitoring and treatment/processing of e-wastes.
Highlights
In 2019, ~ 53.6 million tons of e-wastes generated worldwide.
Discarded e-wastes may be hazardous in nature due to presence of heavy metal compositions.
Precious metals like gold, silver, and copper can also be procured from e-wastes.
Advance tools like artificial intelligence/machine learning can be useful in the management of e-wastes.
Graphical abstract
... At present, the research topics of the utilization of waste PCBs resource mainly focus on the recovery of valuable metals, preparation of nanocomposites and reuse of non-metal components [12,13]. In order to recover metals from waste PCBs, some separation and purification techniques such as chemical methods [14,15], physical methods [16,17] and biological methods [18], are continuously proposed by scholars to achieve the scientific recycling of waste PCBs. Furthermore, some pretreatment technologies including dismantling and crushing process are usually used to improve the recycling efficiency of waste PCBs [19]. ...
The crushing process plays an important role in the separation and purification process of waste printed circuit boards (PCBs). In this work, the fine crushing of waste PCBs was conducted to investigate particle characteristics and metal distribution using a shear crusher. The results demonstrated that a better crushing was obtained with the feed concentration of 183 g/L and crushing time of 60 s. Meanwhile, the coarse and fine particles presented the characteristics of higher circularity and smaller aspect ratio than medium-size particles for waste PCBs. Main metal elements such as Cu, Al, Zn and Fe were distributed in waste PCBs with various particle sizes, and these total metal content in the coarse crushed products was obviously higher than that in the fine crushed products. Overall, waste PCBs can be effectively crushed to a desirable product for subsequent separation and purification process using a shear crusher.
... Acid mine drainage (AMD) is the acidic water obtained from the tail drainage of coal mines and various metal mining sites (Akcil and Koldas, 2006;Kefeni et al., 2017;Qureshi et al., 2016), old mine workings (Tomiyama et al., 2019, open pits (Monjardin et al., 2022), waste dumps (Lambert et al., 2015;Tabelin et al., 2021), and rock excavated through tunnel projects (Tabelin et al., 2018;Tatsuhara et al., 2012). Owing to its strong acidity and the high concentration of soluble metals (Fe 2+ , Fe 3+ , Mn 2+ , Cu 2+ , Zn 2+ , Cd 2+ , and other heavy metals) and SO 4 2− , AMD poses a threat to soil, water resources, and surrounding organisms (Kefeni et al., 2017). ...
Acid mine drainage (AMD) contains abundant iron, sulfates, and various metal ions, and it causes environmental pollution. The traditional AMD lime neutralization forms a layer of iron hydroxide and gypsum on the surface of the lime particles, preventing continuous reaction and leading to excessive lime addition and neutralized sludge production. In this study, an approach for treating AMD using a cyclic process of biooxidation and electroreduction before lime neutralization was proposed, in which the Fe²⁺ in AMD was oxidized to Fe³⁺ and induced to form schwertmannite through Acidithiobacillus ferrooxidans. The remaining Fe³⁺ was reduced to Fe²⁺ using an electric field. After three biooxidation and two electroreduction cycles, 98.2% of Fe and 62.4% of SO4²⁻ in AMD precipitated as schwertmannite (Fe8O8(OH)5.16(SO4)1.37). The yield of schwertmannite reached 33.98 g/LAMD, with a high specific surface area of 112.59 m²/g. The lime dosage and sludge yield of the treated AMD in the subsequent neutralization stage (pH = 7.00) decreased by 85.0% and 74.5%, respectively, than those of raw AMD. The pilot test results showed that the integrated treatment of biooxidation–electroreduction cyclic mineralization and lime neutralization has practical applications.
... Tembaga merupakan logam non-ferrous terpenting kedua setelah alumunium dan banyak dipakai dalam aplikasi industri seperti konstruksi, komponen mesin dan elektronik, serta untuk komponen telkomunikasi (wire) [9]. Kalkopirit merupakan mineral yang keterdapatannya paling banyak sebagai pembawa Cu (Cu-bearingminerals). Mineral lain seperti kalkosit (Cu2S) dan kovelit (CuS) merupakan mineral alternatif lain untuk ekstraksi logam ini [10]. ...
Proses kominusi merupakan langkah awal dalam pengolahan mineral. Efisiensi dan keberhasilan memetakan atau untuk karakterisasi material pada proses ini akan membantu pembangunan strategi pengolahan yang paling tepat untuk pemurnian Cu dari bijih kalkopirit. Sistem kominusi yang dipakai pada penelitian ini terdiri dari 2 proses grinding (jaw crusher dan ball mill). Proses grinding pertama menggunakan jaw crusher belum efektif untuk menggerus bijih kalkopirit. Masih terdapat frekuensi massa yang tinggi pada rentang ukuran lebih besar dari 600 µm. Oleh karena itu, dilakukan penggerusan kedua menggunakan ball mill dengan rasio berat umpan:bola baja = 1:10, kecepatan putar 25 rpm selama 60 menit. Produk grinding kedua memiliki frekuensi massa lebih dari 60% pada rentang ukuran lebih kecil dari 180 µm. Nilai ukuran pada 80% kumulatif massa lolos (P80) pada produk grinding kedua juga berkurang secara signifikan yaitu berada pada rentang ukuran 212-355 µm. Karakterisasi mineral juga telah dilakukan untuk mengetahui konsentrasi elemen dan mineral pada sampel. Cu sebagai target mineral memiliki konsentrasi sebesar 7.57% sedangkan Si sebagai major elemen memiliki konsentrasi sebesar 35.5%. Mineral paling dominan pada sampel adalah kuarsa, kalkopirit, kalkosit dan kovelit dengan konsentrasi masing-masing secara berurutan adalah sebesar 81.10%, 2.76%, 13.28 dan 2.86%.
... The efficiency of the metal bioleaching process from WP-CBs can be increased by externally supplying iron(II) and sulfur to the culture medium especially for low iron content wastes (Lambert et al., 2015;Latorre et al., 2016;). This can be explained by the partial compensation of acid consumption through S0 oxidation, which creates more suitable conditions for the bacteria. ...
Technological innovations and increased demand for electronic devices resulted in production of more and more waste with highmetal content. Worldwide, 50 million tons of WEEE (Waste from Electrical and Electronic Equipment) are generated each year. Giventhe metal content present in electrical waste (e-waste), it is considered to be an urban mine and, if properly treated, can serve as analternative secondary source of metals. Waste printed circuit boards (WPCBs) that constitute approx. 3-5% of WEEE by weight areof particular importance. They contain, on average, 30-40% of metals by weight, with higher purity than in minerals. With environmental and economic benefits in mind, increasing attention is being paid to the development of processes to recover metals and othervaluable materials from WPCBs. The research presented in the article aimed at assessing the usefulness of the biotechnological methodfor leaching of selected metals from e-waste. The results indicate that it is possible to mobilize metals from WPCBs using microorganisms such as Acidithiobacillus ferroxidans bacteria
... Although pyrometallurgical separation has long been the most widely used method for recycling metals from WEEE, the generation of toxic gases, high slag volume, and increasingly stringent environmental regulations have started to discourage the use of this technique (Kim et al., 2011;Zhang et al., 2018). Unlike pyrometallurgy, bioleaching is considered environmentally friendly and economical but features comparatively slow leaching kinetics (Lambert et al., 2015;Li et al., 2020). In contrast, hydrometallurgical processing with chemical leaching has proven flexible, can achieve high selectivity and recovery, has the potential to eliminate secondary wastes (Chen et al., 2015;Li et al., 2020), and, in some cases, allows cleaner processing when compared to the pyrometallurgical route. ...
Currently, the generation of electrical and electronic wastes is growing fast, thereby the reduction of the environmental impacts generated by its inadequate disposal is an ongoing challenge. In this study, a research on the use of monosodium glutamate for copper leaching, with emphasis on the thermodynamics and oxidant characteristics, is presented. Copper dissolution was conducted following a hydrometallurgical route, using monosodium glutamate in alkaline solutions. The effect of oxidizing agents such as hydrogen peroxide (H2O2) and potassium permanganate (KMnO4), and the efficiency of copper leaching with glutamate compared with glycine have been studied. Results, obtained at room temperature, showed 92% recovery of copper using 0.03 M hydrogen peroxide, 0.5 M monosodium glutamate at a pH of 9.44. This novel method would allow the extraction of copper from WEEE at low temperature, using an environmentally friendly leaching amino acid for the recovery of copper from electronic waste.
... Therefore, the technology is not suitable for the treatment in large numbers of waste-cables [11]. This technology can be used as secondary technology treatment if the plastic materials obtained from the mechanical/physical separation still contains some copper (low-copper-content wastecables) [47,48]. According to [11], chemical technology is to treat waste-cables by the use of salt solution or organic solvents which dissolve the plastic material, but do not react with the copper cores. ...
Urbanization, development of economy, increasing population and improved living standards and lifestyle have caused a sharp growth in waste. Inappropriate or inefficient waste disposal techniques can cause serious air, soil, and groundwater pollution, which subsequently can negatively affect the urban environment and threaten the health of residents. The goal of waste management is to move to a circular economy in which waste does not exist. If there is no possible way to reduce or reuse waste, the best solution is recycling it. Recycling brings abundant benefits on the economic and ecological levels levels, and helps reduce overall human health risk of adverse impacts. Recycling of the waste-cables which contain PVC and copper replaces the production of virgin PVC and mining of copper from copper ore, it reduces landfill solid waste pressures, saves energy and water sources, reduces emissions to environment, and also reduces negative impacts from improperly dispose of waste, etc. This paper presents an overview of recycling techniques for the waste-cables containing copper as a core and polyvinyl chloride as an insulating layer or sheath. It also lists advantages and disadvantages of these techniques and importance of recycling this type of waste.
... Also within the category of e-waste are telecommunications and information technology equipment, medical devices, automatic dispensers, lighting equipment such as bulbs, batteries, spent fluorescent tubes, light-emitting diodes (LED), consumer electronics such as battery-operated toys, smoke alarm, microwaves, printers, coffeemakers, electrical toothbrushes, washing machines, and sport and leisure equipment [7,8]. Others classified as e-waste include cathode-ray tubes, fridges, internet routers, activated glasses, lead capacitors, end-of-life vehicles, plastic casting and printed circuit boards [9,10]. ...
The generation of electronic waste (e-waste) is increasing at an alarming rate in South Africa. This waste stream is also emanating from household appliances due to beneficial attributes accrued to the use of these electronic devices. At the same time, these devices are a source of concern considering the environmental impacts as well the threat of health hazards they possess to human wellbeing. In appraising household knowledge and perception on e-waste management in Limpopo Province of South Africa, 200 semi-structured, self-administered questionnaires were used in eliciting data from the participants. The results indicated that 76% of the respondents believed that e-waste streams have negatively affected their environment. Additionally, 85% of the survey households are willing to pay for the proper disposal of their e-waste. Furthermore, the results indicated a statistically significance between gender and knowledge on e-waste management (p-value 0.003) while there was no statistically significant difference between gender and perception (p-value 0.318) on e-waste management. Based on the results, the study recommends awareness and educational campaigns as a step in changing the perception of households on e-waste and environmental consciousness.
... Assuming ideal 100% collection and recycling rates, raw materials in E-wastes are valued at US$ 57 B in 2019 . Unfortunately, only 17.4% of E-wastes were collected and recycled in 2019 while the rest likely ended up in landfills and waste dumps or were incinerated Havlik et al., 2014;Lambert et al., 2015;Mäkinen et al., 2015;Tesfayea et al., 2017). Fig. 2 illustrates the distribution of the most significant porphyry copper deposits in the world. ...
Porphyry ores and E-wastes/WEEE are two of the most important copper-bearing materials on the planet. Over 60% of world copper output comes from porphyry copper ores while E-waste(s) is globally the largest copper-bearing waste category since the 1980s. They also contain critical elements for low-carbon technologies essential in the clean energy transition's success. In this review, a critical analysis of ore distribution/processing, metal extraction, E-waste generation and E-waste recycling is presented, focusing on identifying challenges and how to address them with emerging technologies and sustainable socio-environmental strategies. Access to ore deposits is a major hurdle for mine development while the absence of a consistent E-waste classification and legislation, including poor collection rates, remains serious problems in E-waste recycling. As lower grade porphyry ores are exploited, difficulties in processing/extraction due to mineralogical complexities, very fine particles and the generation of “dirty” concentrates will become more prevalent. For E-wastes recycling, current trends are to develop smaller, more mobile, and eco-friendly hydrometallurgical alternatives to pyrometallurgy that can handle localised compositional and feed variabilities. Finally, more sustainable mine waste management strategies, including better LCIA tools with spatial and temporal dimensions, are needed to limit socio-environmental impacts of resources exploitation and maintain the sector's SLO.
... Bioleaching is defined as the dissolution of metals from mineral ores through the action of microorganisms, followed by the recovery of metals from the solution (Maluckov, 2017). A. ferrooxidans has extensive applications in bioleaching including leaching of various metals from low-grade mines (biomining) such as copper (Nascimento et al., 2019), zinc (Haghshenas et al., 2012), nickel (Pogaku & Kodali, 2006), arsenic (Yan et al., 2017), as well as recovery of metals from electronic waste including printed circuit board (PCB) (Wu et al., 2018), cell/battery (Naseri et al., 2018), and waste electrical cables (Lambert et al., 2015). Other applications include the extraction of metals from wastewater sludge (Ghavidel et al., 2018), contaminated soils (Akinci & Guven, 2011), and industrial wastes (Rastegar et al., 2015). ...
The rusticyanin protein, a blue monomeric copper protein type-1, is one of the main components in the iron-electron transfer chain of the Acidithiobacillus ferrooxidans, and is the product of the rus gene expression. Herein, first the bacterial DNA of Acidithiobacillus sp. FJ2 was extracted. Then, the rus gene sequence and the sequence amino acid rusticyanin protein were determined. The Met148Leu mutation increased the oxidase activity of the rusticyanin protein, thereby enhancing the efficiency of the bioleaching process by bacteria Acidithiobacillus ferroxidans. Met148Leu mutation was created in the rusticyanin protein, then molecular dynamics (MD) simulations and structural analysis were performed. The MD analysis of the wild-type and mutant protein demonstrated a slight instability in the mutant protein and significant instability in the active site of the mutant protein. The usefulness of this study is the genetic manipulation of the native Acidithiobacillus sp. FJ2 bacterium, which can boost the bioleaching efficiency of the bacterium to some extent, and investigating its effects on the structure of a mutant protein using computational methods.
Communicated by Ramaswamy H. Sarma
... These methods achieved significantly higher leaching. While on the other hand, it is essential to maintain the acidification environment in growth media in order to cultivate bacterial culture as well as to maintain the solubilisation process, and also need to add the sulphur or Fe(II) in growth medium (Lambert et al., 2015;Latorre et al., 2016). Current methods are mostly based on a hydrometallurgical approach for gold extraction from e-waste, which may possess secondary pollution. ...
The rapid e-waste volume is generating globally. At the same time, different recycling technologies, mainly the mechanical and chemical methods well studied, while the biological method is the most promising approach. Therefore, this article provides a comprehensive information about extracting valuable metals from e-waste. In addition, this article outlines the process and key opportunity for extraction of metals, identifies some of the most critical challenges for e-waste environmentally sound management practices, and opinions on possible solutions for exiting challenges, and emphasis on importance of advanced recycling technologies that can be utilized, in order to minimize the environmental impact causes due to improper recycling of e-waste.
... Microbes have great potential for e-waste recycling, and integrated biohydrometallurgical processes have been developed for metal recovery mainly form waste printed circular boards (WPCBs) (Luda, 2011), phosphor lamps and cracking catalysts (Reed et al., 2016), waste liquid crystal display (WLCDs) (Higashi et al., 2011), computer gold finger motherboards (Madrigal-Arias et al., 2015), waste electric cables (Lambert et al., 2015). Urban biomining comprises mainly three unit operations based on the use of microorganisms as illustrated in Fig. 3. ...
Reuse and recirculation of products and materials are the basis of the concept of the circular economy (CE). The CE is an innovative proposal that can result in positive impacts such as reduced demand for raw materials, reduced consumption of basic resources, and job creation, as well as preventing negative impacts resulting from
the exploitation and processing of natural resources. Mining is infamous for its potential environmental impact, but mining waste from traditional mining (in the linear economy) may recover material through upcycling techniques, as can urban mining of industrial and post-consumer waste categories (in the circular economy). Urban mining, a form of closed-loop supply chain management, offers an attractive alternative to the management of waste electrical and electronic equipment (e-waste) and, at the same time, as a sustainable way to exploit mineral resources, reduces primary material intake and stimulates the circularity in the supply chain. The present study reviews the main CE solutions for e-waste management, highlighting the importance of recovering and classifying mineral material according to urban mining procedures.
... Few studies have earlier been undertaken involving Acidithiobacillus species, Acidithiobacillus ferroxidans (A. ferrooxidans) and Acidithiobacillus thiooxidans for the metal extraction from E-waste (Lambert et al. 2015;Rodrigues et al. 2015;Yang et al. 2017). Some studies have also been investigated involving fungal strains like Aspergillus niger and Aspergillus flavus for the extraction of metals from E-waste (Chatterjee et al. 2019;Qu et al. 2015). ...
Computer circuit boards are a major electronic waste containing higher concentrations of copper, gold and silver. These metals may be recovered by bioleaching, an eco-friendly process to recover metals from natural ores. However, the application of the bioleaching to electronic waste is still in the infancy stage. Here, the bioleaching capability of Acidithiobacillus ferrooxidans to extract copper from printed circuit boards was investigated at laboratory scale using shake flasks. The effect of initial pH, amount and size of printed circuit boards, and volume of inoculum on copper dissolution rates were evaluated. Results show that the highest dissolution rate of 32.44% was achieved after 7 days of leaching at initial pH 2.0, 10 g/L of waste printed circuit board, 40% v/v of inoculum for 1 mm size of circuit board. The smallest size of 1 mm induces the higher dissolution rates, which is explained by higher surface area and thus better bacterial adhesion. Also, the copper dissolution rates increase with the inoculum volume. Overall, bioleaching of copper from waste printed circuit boards using Acidithiobacillus ferrooxidans is achievable.
... On the following days, the metals were dissolved due to Fe 3+ biooxidation. Indeed, the two different chemical mechanisms occur during the single-step direct metal bioleaching [40]. The ferrous iron oxidation reaction can take place in a chemical system, but it is catalyzed in the presence of A. ferrooxidans. ...
... Copper was preserved in the original slightly corroded form, with almost no volatilization of the metal, and the overall copper recovery efficiency was 99.85%. Lambert et al. (2015) examined the leaching of copper from waste electrical cables by chemical leaching and by leaching cat- alyzed by Acidithiobacillus ferrooxidans. The leaching kinetics and consumption of reagents were evaluated, with over 90% of the copper extracted under the optimal conditions. ...
Cables and wires, which are essential parts of equipment for the transmission of both information and electricity, contain valuable materials including copper (Cu) and aluminum (Al). This experimental work evaluates the use of mechanical processing (grinding and sieving), followed by spouted bed elutriation, for separation of the valuable materials (steel-coated copper, copper, and aluminum) present in waste coaxial and internet cables. A recovery efficiency of approximately 90% was achieved for the steel-coated copper in coaxial cables. For internet cables, the copper recovery efficiency was approximately 87%. These findings demonstrate that it is possible to separate, recover, and recycle the valuable materials (metals) present in waste cables using simple, low-cost, and efficient mechanical processing followed by spouted bed elutriation. © 2019 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences
... Lambert et al. employed leaching methods to recycle copper from waste electric cables; 45-55-g samples of various plastic fragments and copper wires (containing 4.9% copper) were placed in a double jacket reactor with 450-500 mL of solutions that were then tested under abiotic, chemical-leaching conditions (in which thymol was added as a bactericide and ferric iron sulfate was added as the oxidant), and under biotic, bio-leaching conditions (in which Acidithiobacillus ferrooxidans was added as the catalyst). More than 90% of the copper was extracted by either the chemical-or the bio-leaching method (Lambert et al., 2015). Kameda et al. reported a method for the recovery of metal from separated cable waste using chloride volatilization. ...
Waste electric cables from end-of-life vehicles and electronic and electrical equipment present a significant problem in terms of environmental protection and resource recycling. Herein we detail a novel recycling method for thin waste electric cables, by combining polyvinyl chloride (PVC) swelling and centrifugal separation to simultaneously recover PVC and high-purity copper. PVC coverings were swollen in an organic solvent at ambient temperatures, which creates a gap between the covering and the copper wire and facilitates centrifugal separation. Electric cables (12 g) were 100% separated, and more than 95% of the plasticizer was extracted by stirring in 100-mL acetone or ethyl acetate that facilitated the separate recovery of copper, the PVC covering, and the plasticizer. In contrast, >97% separation, with <10% extraction of the plasticizer, was achieved with a mixture of 10 mL butyl acetate and 90 mL water. High-purity copper and PVC with controlled plasticizer content were recovered, which is highly advantageous for recycling both copper and PVC.
Waste recycling as secondary source has become important from the environmental perspective and the circular economy. In this context, any waste can become raw material to manufacture other products, such as nanoparticles. Thus, this study aims to provide a descriptive and critical view of metal recovery techniques and later use them as raw materials for nanoparticle synthesis. After scoping searches, an investigation was carried out and found a gap in the research on synthesizing nanoparticles from secondary sources. The possible technologies to recover metals are hydrometallurgical processes, pyrolysis, and bioleaching followed by purification processes. The advantages and disadvantages were discussed. Based on this analysis, hydrometallurgical processing was identified as the most suitable method and, consequently, the most used method for synthesizing nanoparticles. There is a difference in the size and shapes of nanoparticles synthesized by secondary sources and commercial salts.
The process of depletion of ores accompanied by a permanent increase in the production and consumption of nonferrous metals led to the formation of a continuous shortage of copper rolled products and wire rods in the world economy and trade. To compensate this shortage, secondary raw materials, including, in particular, scrap and wastes of the cable and wire production and civil engineering, are now actively introduced in the commercial production. For this purpose, special equipment and installations were created for cable stripping, i.e., for the separation of cables into metal concentrate and plastic waste. However, the existing technologies of cable cutting, parallel with high levels of dust and noise, are characterized by significant losses of the metal (up to 32%) and low quality of finished products (containing at least 7–8% nonmetallic fraction represented mainly by the protective cable insulation). The indicated protective insulation is based on flexible polyvinyl chloride plastics and special admixtures aimed at increasing the ductility of the cable. In a melting furnace, the insulation ignites and releases into the furnace atmosphere H2, O2, Cl2, HCl, H2O, CO, and CO2, volatile hydrocarbons, and their chlorinated derivatives (chlorides, oxides, tetrahydride, tetramethyltin, etc.), which dissolve in the melt and may increase the concentration of hydrogen and oxygen in it. For this reason, we think that the concentrate obtained as a result of cable stripping is unsuitable for smelting copper and copper-based alloys. It can be used for smelting rough copper ingots, which requires the procedure of repeated refining remelting.
In this connection, modern environmentally friendly cable-cutting technologies are developed with an aim to increase the degree of extraction of the main product (metal core) and improve its quality. The present work is devoted to the study of environmentally friendly recycling (firing) of cable scrap with polyvinyl chloride (PVC) insulation by the method of steam gasification. It was experimentally established that the indicated method makes it possible to obtain a concentrate, which is practically free of PVC insulation and suitable for smelting branded alloys. The application of the steam gasification method for recycling cable scrap and PVC-insulated wastes guarantees 100% yield of the volatile fraction at the temperatures of firing of raw materials lower than the temperatures corresponding to the pyrolysis mode. At the same time, the minimum losses of metal caused by its oxidation in the course of gasification are guaranteed. By processing the experimental data, it was established that, within the temperature range 475–600 °C, the process of steam gasification of PVC cable insulation is controlled by its duration, temperature, and the flow rate of the steam-air mixture. An empirical dependence that can be used to describe this process is obtained in the form f(Xi) = 3.74∙(−0.1093τ + 63.356)·(−65.594T + 63.356)·(−2.4626η + 35.577). It is experimentally established that the balance efficiency of copper extraction from the PVC insulation by the steam gasification method is not smaller than 99.92%.
The incineration of a large number of old cables leads to the problem of green recycling and causes a lot of environmental problems. This paper investigates the effect of copper oxide (CuO) capture of chlorine (Cl) in the pyrolysis recycling of polyvinyl chloride (PVC)-based waste cable outer sheath, focusing on the redistribution of the contaminant Cl components under the action of oxygen (O2). Analytical methods such as ion chromatography and diffraction of X-rays are employed to measure and quantify the dynamic changes of the Cl-containing three-phase products during the pyrolysis process. The results indicate that, compared to copper (Cu), the oxidized state of CuO and O2-rich conditions can enhance the capture of Cl. With increasing O2 supply, 1.71–6.33 mass% of gas-phase Cl and 14.52–29.96 mass% of liquid-phase Cl convert into 16.23–36.29 mass% of solid-phase Cl. CuO reacts directly with the PVC component of the outer sheath in a solid–solid reaction, significantly reducing the generation of polluting Cl-containing aromatic compounds in the liquid-phase tar and synergistically facilitating CaCO3 components to intimately contact with the pyrolysis gas to capture HCl. The originally stable CuCl2 crystals are oxidized again to enter into cyclic adsorption in the form of CuO under O2-rich conditions. Cl is more fixed in the residue and primarily exists in the form of stable and safe CuCl2 and CaCl2 metallic compounds. This study has clearly elucidated the efficient in situ green solidification mechanism of Cl during the treatment of cable waste with CuO in the presence of O2, providing new recommendations for cable sheath formulations and solid waste management.
Aqueous foams have been used in various hydrometallurgical processes, and have recently emerged as an alternative technique for the leaching of metallic copper, using hydrochloric acid and O 2 from air as an oxidant. In the present study, we describe how this technique has been successfully applied to the leaching of copper from waste printed circuits boards (WPCBs). First of all, the use of HCl based foams was successfully applied to the leaching of sole copper, and the impact of the size of copper particles was studied. It was demonstrated that use of mixtures of fine and large particles give excellent results. Then, on ground WPCBs, a first classical leaching stage using aqueous HCl solution was performed in order to remove maximum quantity of reducible metals (aluminum, iron, zinc ...). Then, almost quantitative copper leaching employing HCl based foam was performed. Copper is almost exclusively leached during this stage, and the complete mass balance in 5 major metals present in WPCBs (aluminum, iron, zinc, nickel and copper) is detailed. Kinetics of the copper leaching were greatly enhanced through addition of substoechiometric quantity of cupric ions at the beginning of the process, so that extensive grinding of the waste is not necessary.
The exponential surge in global e-waste has emerged as a critical social, ecosystem, and public health matter. Within this chapter, the authors delve into the multifaceted economic, social, educational, legal, and technological challenges entwined with electronic equipment waste management. It accentuates the imperativeness of devising effective strategies to overcome these hurdles. Insufficient management practices culminate in the emission of perilous substances, thus exacerbating pollution levels and health risks. Numerous nations have adopted regulations and policies to govern the people and proper disposal of electronic equipment waste. In this chapter, the authors explore the utmost significance of managing electronic equipment waste in connection with the Sustainable Development Goals (SDGs). The discourse encompasses exemplary practices and strategies. Conclusively, this chapter emphasizes the paramount importance of robust policies and continuous innovation in achieving sustainable electronic equipment waste management and making valuable contributions towards the realization of the SDGs.
Aims: This study aims to present a comprehensive analysis of bioleaching, the fundamental idea behind it, the emergence of microbes and the bioleaching approaches. Study Design: To do this, this research has been developed on a foundation of significant topics. The researcher used a quantitative approach in this particular investigation. The quantitative study is presented in tables that list the bioleaching processes and efficient microorganisms. Place and Duration of Study: This study was carried out in Chemical Engineering department, Delta State University of Science and Technology, Ozoro, Nigeria. Methodology: The researcher decided on a combination methodology because of the context of the present investigation. The approach of data collection and analysis employing qualitative as well as quantitative methodologies is known as combined research design. Results: The lengthy training period of microorganisms at the laboratory scale, which is significantly impacted by other experimental variables, is one of the key difficulties faced by the bioleaching process. Therefore, the key to increasing the simplicity of bioleaching technologies in large-scale industrial production is to enhance the bioleaching microorganism’s currently in use so that they can continue to be highly active under more complicated reaction conditions. Regarding the microbial problem, biological leaching piles of just a few genes in the offspring of acidophilic microorganisms have been documented. Although some bacterial genomes from acid mine drainage and acidic environments have been used to create replacements, these models cannot fully depict the potential for leaching; in addition, it can be difficult for researchers to obtain samples of microbes from actual production, making further research challenging. Conclusion: In the years to come, microbial use for waste treatment and mineral processing will continue to gain importance on a global scale. The need to process ores with trace amounts of copper and gold, the potential for recycling waste spoils and tailings, financial limitations, and potential legislative changes on the environmental impact of more conventional approaches like hydrometallurgy will all contribute to this. The employment of chemolithotrophic and heterotrophic bacteria will be a significant addition, boosting the leaching rates and metal recoveries and enabling the treatment of resistant ores like chalcopyrite.
Small electronic waste has been addressed in this chapter. With this, issues such as consumption and generation, composition and recycling techniques were raised. The equipment/waste addressed were cell phones and smartphones, LED lamps, computers, and electrical wires and cables, which were chosen due to their great generation, for being more current technologies, their great applicability and quantity, and variety of valuable and critical materials in their compositions. All this waste shows a notable quantity and variety of precious and technological metals, and of rare-earth elements, all metals of great interest and research today. All except electrical wires and cables show considerable portions of gold, for example, which is a precious metal of great applicability, and which has been achieving high yield values, being, with this, one of the metals most studied by researchers. On the other hand, electrical wires and cables are waste, which is present in almost every WEEE, and are rich in copper and PVC, which are materials of great use in the most diverse areas. In any case, there is a need for the development of viable techniques of recovery of these metals, as well as the development of viable industrial processes. Important steps, such as disassembly and mechanical processing, should be developed, as they enable better revenues, in addition to the development of more sustainable and productive recovery procedures. As well as the development of designs that aim to facilitate the end of life of these products, seeking to meet the precepts of the tripod of sustainability, industrial ecology, and, more recently, the circular economy strategy, where all materials, not only metals, of this waste are recovered, valued, and recycled.
Biomachining has been investigated as a sustainable and effective alternative to conventional prototyping techniques for molding polymeric materials for their subsequent use as microfluidic devices. A novel and simple process based on the combination of a Pressure Sensitive Adhesive mask and a varnish has been proposed for preparing metal workpieces as an alternative to photolithography, with the latter being the most widely used technique for protecting workpieces. As far as the bioprocess is concerned, it has been applied in successive mold-etching and oxidant bio-regeneration stages. Metal solubilization has proven to be repeatable in several consecutive mold-etching stages when using the regenerated oxidant solution. As a result, the lifespan of the biomachining medium has been prolonged, contributing to process sustainability. An equation with two restrictions has been proposed to predict the time required to obtain a mold with a fixed height, as metal solubilization evolves differently between the first and subsequent hours. Finally, the bio-engraved copper pieces have acted as effective molds in the fabrication of self-powered polydimethylsiloxane microfluidic devices. This new biomachining application is therefore an effective and ecofriendly process for producing microfluidic devices.
In this paper, the dissolution kinetics of cement copper powder in sulfuric acid solutions containing cupric ions was examined. It was observed that the dissolution rate of copper increased with increasing the acid concentration, temperature, and stirring speed. It was determined that the dissolution rate of copper enhanced with increasing the cupric ion concentration up to 0.025 M. It was found that the temperature and concentration of cupric ion had more considerable effects on the dissolution of copper powder. The kinetic analysis of the process was performed, and it was observed that it fits the first order pseudo-homogenous reaction model. The activation energy was calculated to be 31.1 kJ/mol.
The recycling of waste printed circuit boards (PCBs) has been an emerging problem due to its hazardous nature. In this work, the flotation performances of metallic elements were investigated and evaluated at various temperature and collector dosage. The content of metals in flotation products was measured by the X-ray fluorescence spectrometer. When using 740 g/t diesel oil (DO) as the collector at 20 °C, recovery efficiency of Cu, Al, Zn and Ag reached the maximum values of 91.06%, 82.50%, 95.87% and 90.87%, respectively. When using laurylamine (LAM) as the collector at 20 °C, recovery efficiency of Cu, Al, Zn and Ag reached the respective maximum values with corresponding LAM dosage of 370 g/t, 740 g/t, 370 g/t and 1110 g/t, respectively. The flotation results indicated that using DO can achieve the better recovery of these metals from waste PCBs than using LAM. Finally, an environmentally friendly process for recovering valuable metals from waste PCBs using reverse flotation was considered.
Poly(vinyl chloride) (PVC) swelling coupled with ball milling was employed for the simultaneous recovery of high-purity Cu and PVC from waste wire harness under ambient conditions. The experimentally determined performances of 15 organic solvents for PVC swelling and phthalate plasticiser extraction were compared with those predicted considering Hansen solubility parameters. As a result, n-butyl acetate and acetone were identified as the two best solvents for adequate PVC swelling without PVC dissolution and almost complete plasticiser extraction within 60 min. The swelling was concluded to contribute to the control of phthalate plasticisers, the use of which in wire harness has recently been limited by the Restriction of Hazardous Substances (RoHS) directive. Cables swollen with n-butyl acetate or acetone were subjected to dry ball milling for ~ 60 min to completely separate PVC and Cu and achieve the quantitative recovery of these components from 20-cm-long cables. Thus, this work unveils the high potential of recycling the otherwise non-recyclable long and non-uniform waste wire harness cables and is expected to impact the related (e.g., automotive, electrical, and electronics) industries, contributing to the establishment of a more sustainable society.
Critical metals are key raw materials for new generation clean energy production. The extraction of critical metals often follows the difficult processing of primary ores and they are many times recovered as the companion metals. With the depletion of primary reserves, the focus has now shifted to processing the urban mines, like electronic (e‐)waste. Among the different types of e‐waste, the waste printed circuit boards (WPCBs) are the major reservoir of high‐value critical metals and are usually treated by the traditional pyro‐ and/or hydro‐metallurgical techniques. However, the application of microbial activities in metals recycling is rapidly emerging as a green technology in comparison to smelter or chemical processing. The application of microorganisms (bacteria/fungi) in WPCBs’ recycling is being increasingly explored in order to meet the parallel objectives of resource recovery and pollution mitigation. Therefore, the present article assesses the current frontiers in bioleaching of critical metals from WPCBs and contains discussions on process fundamentals, challenges, and perspectives. The applicability of microbial recycling of WPCBs at a higher scale in terms of a circular economy and urban mining notion, the techno‐economic analysis, and environmental sustainability in comparison to the chemical processing route are also discussed. © 2020 Society of Chemical Industry
Nowadays, large amount of municipal solid waste is because of electrical scraps (i.e. waste electrical and electronic equipment) that
contain large quantities of electrical conductive metals like copper and gold. Recovery of these metals decreases the environmental
effects of waste electrical and electronic equipment (also called E-waste) disposal, and as a result, the extracted metals can be used
for future industrial purposes. Several studies reported in this review, demonstrated that the biohydrometallurgical processes were
successful in efficient extraction of metals from electrical and electronic wastes. The main advantages of biohydrometallurgy are
lower operation cost, less energy input, skilled labour, and also less environmental effect in comparison with pyro-metallurgical and
hydrometallurgical processes. This study concentrated on fundamentals and technical aspects of biohydrometallurgy. Some points of drawbacks and research directions to develop the process in the future are highlighted in brief.
Printed circuit boards (PCBs), a typical end of life electronic waste, was collected from an E-waste recycling company located in the Netherlands. Cu and precious metal concentration analyses of the powdered PCBs, confirm that the PCBs is multi metallic in nature, rich but contains high concentrations of Cu, Au, Ag, Pd and Pt. Ferric sulfate concentration (100 mM), agitation speed (300 rpm), temperature (20 °C) and solid to liquid ratio (10 g L-1) were found to be the optimum conditions for the maximum leaching of Cu from PCBs. The ferric sulfate leachates were further examined for selective recovery of Cu as Cu sulfides. The important process variables of sulfide precipitation such as lixiviant concentration and sulfide dosage were investigated and optimized 100 ppm of ferric sulfate and (Cu:sulfide) 1:3 molar ratio, respectively. Over 95% of the dissolved Cu (from the multi metallic leachates) was selectively precipitated as copper sulfide under optimum conditions. The characterization of the copper sulfide precipitates by SEM-EDS analyses show that the precipitatesmainly consist of Cu and S. PCBs can thus be seen as a potential secondary resource for copper.
This work focuses on constructing a bio-electro-hydrometallurgical platform to efficiently recover cobalt (Co), lithium (Li), and manganese (Mn) from the cathode active materials (CAMs) of spent lithium batteries. A bioleaching process and selective adsorption by PC-88A/TOA-modified granular activated carbon were both incorporated into an electrokinetics approach to achieve excellent recycling performance. The technical feasibility was comprehensively investigated in terms of four aspects, including the domestication of microorganisms, the evaluation of the bioleaching process, the equilibrium adsorption of the adsorbent, and the electrokinetic recovery. Potential sulfur-oxidizing bacteria were screened and domesticated to a high concentration of pyrite pulp. The voltage gradient and the remediation time both had obvious influences on the recovery of the target elements in the electrokinetic process. Maximum recoveries of 91.45%, 93.64% and 87.92% for Co, Li, and Mn, respectively, were achieved from the CAMs of spent lithium-ion batteries via the electrokinetics process. The indirect oxidation of pyrite provided the necessary reductants for the platform. The transformation of sulfur (S) to H2SO4 as a result of bio-oxidation by bacteria strains supplied additional H⁺ ions to facilitate the reduction reaction, and acid dissolution mitigated the drawbacks caused by the uneven distribution of pH in the electrokinetics process.
Material characteristics of pure copper, pure cobalt and Cu–Co metal-powder composite were comparative studied through biomachining by Acidithiobacillus ferrooxidans (A. ferrooxidans) in three groups of culture solutions. Material removal mechanisms of Cu–Co metal-powder composite involved in biomachining were explored. It was first observed that the pure cobalt and Cu–Co metal-powder composite were machined by the A. ferrooxidans. The material removal of three workpieces presented linear increase along the machining process due to the metabolic activity of the A. ferrooxidans. Different with the pure metal, the material removal mechanism of Cu–Co metal-powder is explained by the dual effect of micro-galvanic corrosion and participation of Cu²⁺ and Fe³⁺ for oxidization of cobalt.
End-of-life printed circuit boards have been subjected to proprietary pyrolysis resulting in a copper-rich char containing liberated metals. For downstream processing and copper recovery, the char was exposed to two different leaching solutions: one containing mixed microbial consortia originating from bioleaching of coal spoils and a cell-free chemical solution for comparative purpose. The influence of char pre-treatment, reactor type, temperature and type of leaching solution on the dissolution of the zero-valent copper was studied. It was found out, that for bringing copper in solution, the type of leaching solution had less pronounced effect than the type of reactor. Other than ferric iron concentration and temperature, the bacterial presence has shown effect on copper leaching kinetics and process efficiency. The fact that copper was continuously dissolved by ferric iron at initial concentrations well below the stoichiometric required ratio, demonstrated microbial regeneration of ferric iron and its back-cycling in the system. In case of the absence of microbe, the regeneration of ferric iron is driven by oxidation in the presence of O2 and H⁺. A simplified kinetic model of copper dissolution suggested that the reaction order depends upon the initial concentration of ferric iron.
The present work was aimed at studying the bioleachability of metals from electronic scrap by the selected moderately thermophilic strains of acidophilic chemolithotrophic and acidophilic heterotrophic bacteria. These included Sulfobacillus thermosulfidooxidans and an unidentified acidophilic heterotroph (code A1TSB) isolated from local environments. Among the strategies adapted to obtain enhanced metal leaching rates from electronic scrap, a mixed consortium of the metal adapted cultures of the above-mentioned bacteria was found to exhibit the maximum metal leaching efficiency. In all the flasks where high metal leaching rates were observed, concomitantly biomass production rates were also high indicating high growth rates. It showed that the metal bioleaching capability of the bacteria was associated with their growth. At scrap concentration of 10 g/L, a mixed consortium of the metal adapted cultures was able to leach more than 81% of Ni, 89% of Cu, 79% of Al and 83% of Zn. Although Pb and Sn were also leached out, they were detected in the precipitates formed during bioleaching.
The leachability tests for manufacturing scrap TV boards (STVB) have indicated the release of metals beyond the limit levels with potential problems for environmental pollution. Treatment of STVB is therefore requisite for its safe disposal in landfills. The nitric acid leaching of STVB for the removal/recovery of valuable metals (Cu and Ag) was studied by adopting the Box–Behnken design. Statistical analysis of data has revealed that the concentration of nitric acid is the most influential parameter affecting the leaching process. Effects of solids ratio and temperature on the rate and extent of the extraction of copper were also proved to be statistically significant. However, the interaction effects of these parameters were found to be insignificant. The leaching kinetics were consistent with the shrinking particle model under chemical control with an activation energy of 38.6 kJ/mol. High concentrations of nitric acid (2–5 M HNO3) were required to achieve high copper extractions (88.5–99.9%) at a pulp density of 6% w/v. The extraction of silver was enhanced from 14% to 68% with increasing the concentration of nitric acid from 1 to 5 M. These findings also demonstrate that copper may well be selectively extracted from STVB by adjusting the concentration of nitric acid.
In this work, a Brønsted acidic ionic liquid, 1-butyl-3-methyl-imidazolium hydrogen sulfate ([bmim]HSO4), was used to leach copper from waste printed circuit boards (WPCBs, mounted with electronic components) for the first time, and the leaching behavior of copper was discussed in detail. The results showed that after the pre-treatment, the metal distributions were different with the particle size: Cu, Zn and Al increased with the increasing particle size; while Ni, Sn and Pb were in the contrary. And the particle size has significant influence on copper leaching rate. Copper leaching rate was higher than 99%, almost 100%, when 1g WPCBs powder was leached under the optimum conditions: particle size of 0.1-0.25mm, 25mL 80% (v/v) ionic liquid, 10mL 30% hydrogen peroxide, solid/liquid ratio of 1/25, 70°C and 2h. Copper leaching by [bmim]HSO4 can be modeled with the shrinking core model, controlled by diffusion through a solid product layer, and the kinetic apparent activation energy has been calculated to be 25.36kJ/mol.
Microbiological processes were applied to mobilize metals from electronic waste materials. Bacteria Thiobacillus . . thiooxidans, T. ferrooxidans and fungi Aspergillus niger, Penicillium simplicissimum were grown in the presence of electronic scrap. The formation of inorganic and organic acids caused the mobilization of metals. Initial experiments showed that microbial growth was inhibited when the concentration of scrap in the medium exceeded 10 g Ly1. However, after a prolonged adaptation time, fungi as well as bacteria grew also at concentrations of 100 g L y1. Both fungal strains were able to mobilize Cu and Sn by 65%, and Al, Ni, Pb, and Zn by more than 95%. At scrap concentrations of 5-10 g L y1, Thiobacilli were able to leach more than 90% of the available Cu, Zn, Ni, and Al. Pb precipitated as PbSO while Sn 4
Representative samples of Küre (Turkey) massive rich copper ore were leached in acidic ferric sulfate solutions in order to recover copper and its associated metals (Zn, Co, Ni) present in the ore. The effects of leaching time, ferric ion concentration, acid concentration, solid/liquid ratio, temperature and silver sulfaste addition on metal leaching recoveries were investigated. Optimum leaching conditions and leaching kinetics were determined. Formation of elemental sulfur, which creates a diffusion barrier, was elucidated. In order to remove the retarding effect of elemental sulfur, silver ions were introduced to the leach medium and significant improvements were observed, especially in copper dissolution. Activation energies were found to be 36.7 kJ/mole for Cu and 43.3 kJ/mole for Zn dissolutions. The rate-controlling step was found as the diffusion of ferric ions into the solution filling the pores of sulfur layer formed on the surface of partially leached ore particles.
The effects of suspended, inert solids concentration, ferrous iron concentration and dissolved oxygen concentration on the kinetics of iron oxidation by Thiobucillus ferrooxidans are reported. It is shown that the maximum specific growth rate for this organism, oxidizing ferrous iron, is of the order of 0.1 h⁻¹. Competitive inhibition by femc iron is demonstrated. The dissolved oxygen concentration below which the bacteria will not grow is 0.20 mg/L. The dissolved oxygen concentration below which O2 availability is limiting is around 0.29-0.7 mg/L. 10.4 millimols of CO2 are fixed by the bacteria per mol of ferrous iron oxidized. 0.0185 mg of bacterial carbon are generated per mg of O2 consumed. Comparative mass transfer rates for O2 and CO2 are discussed. Oxidation rates decreased significantly in shake flasks as suspended solids concentrations rose above 0.5%, whereas in stirred tanks solids concentrations up to 15% had little effect on oxidation rate.
The leaching step of an integrated hydrometallurgical process for the selective recovery of metals from polymetallic concentrates has been investigated. This concentrate has been produced by physical treatment of Fine Shredder Residues derived from a shredding plant processing a mixed feed of metallic scraps, waste electric equipments and end-of-life vehicles. Bacterially assisted leaching experiments have been carried out using a copper-adapted consortium of mesophilic bacterial strains. The influence of various operating conditions such as stirring speed, temperature (25–50 °C), pulp solids density (5–20%) and initial iron concentration (0–15 g/L) has been studied. Temperature and stirring speed have proved to be the most influential parameter regarding copper dissolution kinetics, while pulp solids density and initial iron concentration have been found to have a subordinate importance. In optimum conditions, 95% extractions of zinc and copper were achieved within 48 h. Bacterial presence has been found beneficial in terms of catalysing copper dissolution.Highlights► Bio hydrometallurgy should be regarded as a way to recycle polymetallic wastes. ► Very high copper recoveries have been achieved. ► Strong influence of temperature and agitation speed. ► Significant upgrading of precious metals, tin and lead in the leach residue.
Effects of two acidophiles on metals recovery in printed circuit boards (PCBs) were investigated. Based on the phenomenon that PCBs addition times and amounts adversely inhibited bacterial growth and thus lowered metals bioleaching capacity, novel strategies of multiple PCBs additions (4 g/l at 48 h, 6 g/l at 96 h and 8 g/l at 144 h) were developed in separated culture of Acidithiobacillus thiooxidans and Acidithiobacillus ferrooxidans. As a result, percentages of Cu, Ni, Zn and Pb leached by A. thiooxidans were 78, 73, 75 and 71%, and corresponding values were 80, 73, 76 and 72% by A. ferrooxidans after 240 h cultivation. Further applying the strategies to mixed culture of two acidophiles, extraction percentages of Cu, Ni, Zn and Pb were 94, 89, 90 and 86%, respectively. Moreover, increased redox potential and lowered pH in filtrate were observed, suggesting the mechanism involved in enhancing metals recovery in mixed culture.
The aim of this paper is to understand the factors that influence copper leaching from electronic scrap. It is revealed that the bioleaching is greatly influenced by process variables such as Fe3+ concentration, quantity of stock culture added, and pH. Before starting the leaching process, A. ferrooxidans was cultivated for 3–4 days as stock culture, until the concentration of Fe3+ ions had reached about 7.00 g/L, which was considered strong enough to dissolve metallic copper. The results show that high leaching rates of copper could be achieved in the presence of 6.66 g/L of Fe3+, 100% addition quantities of stock culture, and pH 1.5. It is concluded that bioleaching copper from printed circuit boards (PCB) using Acidithiobacillus ferrooxidans (A. f.) is feasible.
The influences of H+, Fe2+, Fe3+ and Cu2+ ion concentrations and their different combinations on the iron oxidation by an enrichment culture dominated by Leptospirillum ferriphilum were studied in batch experiments and continuous-flow fluidized-bed reactors. The iron oxidation rate did not significantly vary in the pH range of 0.9–1.5 and was only partially inhibited at pH 0.7. Ferric and ferrous iron at 5 and 24 g L−1, respectively, had little or no effect on iron oxidation by the enrichment culture and the iron oxidation rate slightly decreased at higher concentrations. At a loading rate of 3 g Fe2+ L−1 h−1, 2 g L−1 Cu2+ did not affect the iron oxidation rate, whereas at a loading rate of 10 g Fe2+ L−1 h−1 it reduced the rate by 69%. The maximum iron oxidation rate was 10 g Fe2+ L−1 h−1 at pH 0.9 and in the presence of 21 g L−1 Fe2+ and 2 g L−1 Cu2+.
The objectives of this study were to evaluate the solubility of copper in waste printed circuit boards (PCBs) by bacterial consortium enriched from natural acid mine drainage, and to determine optimum conditions of bioleaching copper from PCBs. The results indicated that the extraction of copper was mainly accomplished indirectly through oxidation by ferric ions generated from ferrous ion oxidation bacteria. The initial pH and Fe(2+) concentration played an important role in copper extraction and precipitate formation. The leaching rate of copper was generally higher at lower PCB powder dosage. Moreover, a two-step process was extremely necessary for bacterial growth and obtaining an appropriate Fe(2+) oxidation rate; a suitable time when 6.25 g/L of Fe(2+) remained in the solution was suggested for adding PCB powder. The maximum leaching rate of copper was achieved 95% after 5 days under the conditions of initial pH 1.5, 9 g/L of initial Fe(2+), and 20 g/L of PCB powder. All findings demonstrated that copper could be efficiently solubilized from waste PCBs by using bacterial consortium, and the leaching period was shortened remarkably from about 12 days to 5 days.
Bioleaching processes were used to mobilize metals from printed wire boards (PWBs). The bacteria Acidithiobacillus ferrooxidans (A. ferrooxidans) and Acidithiobacillus thiooxidans (A. thiooxidans) isolated from an acidic mine drainage were grown and acclimated in presence of PWBs and then used as bioleaching bacteria to solubilize metals from PWBs. The experimental results demonstrate that all the percentages of copper, lead, zinc solubilized into the leaching solution from actual PWBs basically increased with decrease of sieve fraction of sample and decrease of PWBs concentration. The concentration of PWBs should be controlled under the range from 7.8 to 19.5 g l(-1). Under 7.8 g l(-1) of the concentration of PWBs, the percentages of copper solubilized are 99.0%, 74.9%, 99.9% at 0.5-1.0mm of sieve fraction at 9 d of leaching time by the pure culture of A. ferrooxidans, the pure culture of A. thiooxidans, and mixed culture of A. ferrooxidans and A. thiooxidans, respectively, while the percentages of copper, lead and zinc solubilized are all more than 88.9% at <0.35 mm of the sieve fractions of sample at 5d of leaching time by the above three kinds of cultures. Variation of pH and redox potential of leaching solution with time implied that Fe(3+) oxidized from Fe(2+) in the culture medium in presence of A. ferrooxidans caused the mobilization of metals. It is concluded that A. ferrooxidans and A. thiooxidans were able to grow in the presence of PWBs and the pure culture of A. ferrooxidans, and the mixed culture of A. ferrooxidans and A. thiooxidans can not only efficiently bioleach the main metal copper but also bioleach other minor metals such as lead, zinc as well.
Copper extraction from scrap cables by biotechnological means
- S Gaydardzhiev
- D Bastin
- P.-F Bareel
Gaydardzhiev, S., Bastin, D., Bareel, P.-F., 2010. Copper extraction from scrap cables by biotechnological means. In: XXV International Mineral Processing Congress (IMPC) – Proceedings. pp. 3751–3757.