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![Simplified flow sheet of black copper smelter process (secondary copper smelting) [59]. Reprinted with permission from [59], 2013.](profile/Abdul-Khaliq-2/publication/261181219/figure/fig3/AS:296890290720774@1447795569420/Simplified-flow-sheet-of-black-copper-smelter-process-secondary-copper-smelting-59.png)
Simplified flow sheet of black copper smelter process (secondary copper smelting) [59]. Reprinted with permission from [59], 2013.
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The useful life of electrical and electronic equipment (EEE) has been shortened as a consequence of the advancement in technology and change in consumer patterns. This has resulted in the generation of large quantities of electronic waste (e-waste) that needs to be managed. The handling of e-waste including combustion in incinerators, disposing in...
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... and secondary copper smelting routes are adopted to recycle and extract PMs from e-waste. It is reported that copper smelting routes are more environmentally friendly compared to lead smelters that generate toxic fumes [36]. Copper smelting facilities near populations will minimize the cost of e-waste transportation and therefore the recycling economy will be improved. These advantages allow copper smelters to be installed near cities where e-waste is generated. In these processes, PMs are recovered via a conventional electrorefining process where they are segregated in slimes [59]. Commonly, copper smelting routes including matte and black copper are used for e-waste recycling. In the sulfur-based route (primary copper smelting), copper matte (40%) and blister copper (98.5%) are produced. Finally, blister copper is refined by fire refining to produce pure copper. In the black copper route (secondary copper smelting), crude copper is produced during a reduction process and is refined by oxidation in a converter. The black copper is an attractive route because it can receive high levels of impurities including Fe, Zn, Pb and Sn. These impurities are removed by oxidation as shown in Figure 3. The black copper smelting process consists of reduction and oxidation cycles. Impurities are mostly segregated into the vapor phase and are discharged in the off gas ...
Citations
... Furthermore, e-waste contains multiple metallic components, which requires a comprehensive understanding of the process dynamics and interactive mechanisms to maximize recovery potential. Temperature plays a crucial role in these processes, and knowledge of the process thermodynamics of base metals and analysis of the composition of the intermediates formed are essential for process optimization [20]. Future research efforts should focus on these important areas in order to provide better methods for the recovery of metals from e-waste. ...
Due to technological development and increased production efficiency in all industries, recovery of metals from secondary sources is one of the most important issues. Copper is used in a variety of residential and industrial applications, including power generation and transmission (infrastructure), building wiring, transportation, industrial machinery, commercial durables, and electrical and electronic products due to its unique physical and chemical properties, such as high ductility, malleability, electrical and thermal conductivity, and excellent corrosion resistance. For these reasons, electronic waste is a well-known secondary resource rich in copper. This topic focuses on the statistical study of electronic waste and the metals it contains, the mineralogical and elemental identification of copper in electronic waste, and the study of the steps and methods for recovering copper from electronic waste, especially pyrometallurgy, hydrometallurgy, biohydrometallurgy, and their combination.
... This methodology provides a unique leaching-sorption method for gold recovery and 85% of gold was recovered (from AT leachant) by the proposed combination. Khaliq et al. (2014), [14] presented the various metallurgical techniques for the extraction of precious metals from e-wastes. The authors also highlighted the importance of e-waste recycling in the context of the development of electronic technologies and rising number of e-wastes. ...
... This methodology provides a unique leaching-sorption method for gold recovery and 85% of gold was recovered (from AT leachant) by the proposed combination. Khaliq et al. (2014), [14] presented the various metallurgical techniques for the extraction of precious metals from e-wastes. The authors also highlighted the importance of e-waste recycling in the context of the development of electronic technologies and rising number of e-wastes. ...
... The economic and environmental challenges associated with traditional methods, as highlighted in the literature, reinforce the necessity for innovative approaches. Inclusion of studies such as [13] and [14] broadens the context, recognizing the global nature of electronic waste challenges. These studies contribute to the evolving landscape of e-waste recycling technologies, positioning this research within a larger framework of global efforts. ...
The issue of e-waste recycling is the uncharted territory in in most developing countries with a full potential to be a source of secondary resources. Every year there are tonnes of electronic materials with precious metals in them that lie in the landfills as there are no economically viable methods to extract them. Many people have attempted to recover precious metals from e-waste and the challenge is to come up with a method that is fast, clean (environmentally friendly), cheap and safe. The aim of the research was to recover precious metals that are of high value such as gold using hydrometallurgical methods. To achieve the faster reaction rate, the process involved heating H2SO4 to about 70±10℃ and then washing with water after using a 1:1 solution of water to HNO3 to get rid of other remaining metals. Afterwards, a 10:1 ratio of HCl to H2O2 was added in order to strip the components of gold. Precipitation of the gold solution was done using Na2S2O5 and left for 4 hrs to settle. The final result, after precipitating and drying , showed that with the devised method, it is possible to recover gold at a shortest possible period of 4 days.
... These routes for the recovery of resources might be grouped as physical, hydrometallurgical, and pyrometallurgical processes. While the former technologies are generally simple and low cost, they present a partially poor efficiency in metals recovery, and therefore the products cannot be directly recycled; however, a physical pre-treatment is generally carried out prior to any other methods, to ensure a high final efficiency [19]. The hydrometallurgical routes (Ezinex [20], Zincex [21]) would allow for a higher efficiency and selectivity for a given range of metals, i.e., Zn, but the large amount of leaching agent needed reflects high costs and pollution, also leading to a final slag, which cannot be recycled [22]. ...
The EU steel industry accounts for a crude steel production of 140 Mt/y, provided by the integrated (57%) and electric (43%) routes, which respectively require up to 6.0 and 0.6 MWh/tCrud-eSteel of energy input, and emits on average 1.85 and 0.4 tCO2/tCrudeSteel. The mitigation of such CO2 emissions is crucial, and would involve the direct avoidance of carbon, improvement of energy efficiency , and carbon capture. However, the environmental burden of the steel industry cannot be limited to this, given the very large amount (approximately 5 Mt) of residues landfilled every year in the EU. This practice cannot be sustained anymore, since it represents a detrimental waste of resources and burden to the environment. These aspects require prompt action to meet the Green Deal goals envisioned for 2030. This review paper aims to provide an overview of the main state-of-the-art technologies commercially (and not) available for the effective treatment of a wide variety of residues. To enrich this overview with further potential candidates towards a more sustainable steel manufacturing process, the combined application of two technologies (a plasma reactor and a RecoDust unit for the recovery of metals and minerals, respectively) at TRL 5-6 is also investigated here.
... The composition of plastics has been determined based on the average proportions of various plastic types found in different studies about recycling of refrigerators [23][24][25]. Finally, the composition of PCB had been determined based on previous research's on metal recovery from WEEE [26]. ...
... In the smelter, plastics within the scrap serve as an alternative source of energy, replacing coke. Additionally, metals such as Al, Mn, and Mg will not be reclaimed, resulting in their conversion into oxides in the slag phase [26]. This stage involves subjecting the Copper scrap material to high temperatures (1300 °C), under a pO2 of 10 −8 atm and enriched oxygen, also with the presence of fluxing agents such as FeO, CaO, SiO2, The This route commences at the smelter-reducer, followed by the converter-oxidizer stage. ...
... In the smelter, plastics within the scrap serve as an alternative source of energy, replacing coke. Additionally, metals such as Al, Mn, and Mg will not be reclaimed, resulting in their conversion into oxides in the slag phase [26]. This stage involves subjecting the Copper scrap material to high temperatures (1300 • C), under a pO 2 of 10 −8 atm and enriched oxygen, also with the presence of fluxing agents such as FeO, CaO, SiO 2 , The purpose is to generate a Cu content in black copper up to 80 wt.-% as well as 1 wt.-% of Cu 2 O in slags and minor metals in the off gas phases [30]. ...
This study outlines a recycling initiative conducted at Rekular GmbH, focusing on the recycling of 100 refrigerators. The recycling process employed a combination of manual dismantling, depollution, and mechanical processing techniques. Manual dismantling followed a predefined protocol to extract various materials, while the mechanical and physical processes involved shredding, zigzag, magnetic, and eddy current separation (ECS) to liberate and separate different materials. The resulting ferrous, non-ferrous and polymer product fractions were analyzed and categorized, providing valuable insights into the quality of interim products in the refrigerator recycling process. Simulations were then performed using FactSageTM version 8.2 and HSC Chemistry 10 version 10.3.7.1 software to simulate the recovery of metals from the ferrous and non-ferrous fractions using pyro metallurgical and hydrometallurgical methods. An electric arc furnace (EAF) was utilized for iron (Fe), while a re-smelter process for aluminium (Al), and the black copper route was simulated for copper (Cu) recovery. The recovery rates including metallurgical, mechanical, and physical processes are as follows: Fe (78%), Al (68.4%), and Cu (52.4%). In contrast, the recovery rates through metallurgical processes are as follows: Al (99%), Fe (79%), and Cu (88%). This discrepancy is attributed to losses of these elements resulting from incomplete liberation in mechanical processing. Additionally, a product/centric approach was applied and the recycling index reached 76% for recovery the Al, Cu, and Fe metals in a refrigerator recycling process. Turning to the environmental impact evaluation within the life cycle assessment (LCA), the process unit with the highest emissions per refrigerator in the recycling process was the use of nitrogen during the shredding process, accounting for 3.7 kg CO2 eq/refrigerator. Subsequently, the consumption of medium voltage electricity from the German grid during mechanical and physical separations contributed to 0.6 kg CO2 eq/refrigerator. The EAF, and electrolytic refining stages in the metallurgical recovery process also had a notable impact, generating 10.7 kg CO2 eq/refrigerator.
... Some of the parts of electronics that contain cadmium include: batteries, printed circuit boards, semiconductor chips, cathode ray tubes, printer's drum with toner SMD chip resistors, etc. [29,35]. The dismantling and indiscriminate burning of these electronics parts on the disposal site may have caused the release of such high mean Cd concentrations seen in the results displayed in Fig. 3(b). ...
The massive influx of electronics into Nigeria has led to environmental challenges due to increase in the production of electronic waste, which causes serious health and pollution problems. This study investigated the level and impact of heavy metals in 30 soil samples from an electronic waste disposal site in southwest Nigeria, using appropriate standard methods. The range concentrations of the heavy metals were 1615 mg/kg Pb, 20 mg/kg Cr, 266.32 mg/kg Ni, 22.39 mg/kg Cd and 242.03 mg/kg Cu at depth 0-15cm while 1453.56 mg/kg Pb, 26.31 mg/kg Cr, 497.11 mg/kg Ni, 17.04 mg/kg Cd and 230.31 mg/kg Cu were observed at depth 15-30 cm. The concentrations of the heavy metals exceeded the allowable limits, except for Cr. The mean degree of contaminations, 18.15 and 14.35, were observed at depths 0-15 and 15-30 cm respectively and indicated considerable and moderate degree of contamination by the heavy metals, respectively. The mean Potential index of 323.52 and 225.79 at depth 0-15 cm and 15-30 cm showed sever toxicity and moderate toxicity, respectively. The-. of Pb at both depths indicated extreme contamination. This study reveals sever potential environmental and health hazards in the neighborhood, ecosystem, and community, and advises that the government should establish a national policy on e-waste and regulate testing of all electronics imported under the names of reuse, donation and recycling, which will halt the importation of e-scraps (e-waste).
... PCB consists of a group of toxic substances that can cause genetic disorders in those who are exposed to them because they promote the creation of micronuclei and chromosomal aberrations when released into the environment via air, soil, water, or landfills [5]. Before disposal of PCBs, the metals present in them can be recovered by different processes, such as pyrometallurgical processing like (i) incineration and pyrolysis, (ii) hydrometallurgical processes, and (iii) chemical leaching and bioleaching processes [6]. All the above-mentioned methods are costlier and time-consuming procedures; moreover, only a few informal sectors are doing this to recover precious metals from PCBs. ...
Lignocellulosic biomass extracted from plants that contain rich amounts of cellulose, hemicellulose, and lignin content can replace synthetic fibers in many engineering applications and is biodegradable. However, e-waste is rapidly evolving into one of the most serious environmental issues in the world owing to the presence of several toxic compounds that can contaminate the environment and pose a threat to human health. Printed circuit boards (PCBs) are one of the major components available in e-waste. In this research work, waste PCB (WPCB) powder is mixed in suitable proportions of 5%, 10%, 15%, and 20% with a lignocellulosic sisal woven fabric fiber mat, and blended with epoxy resin using the vacuum-assisted hand lay-up method. To determine the effect of particle size on the fabricated composites, mechanical, thermal, water absorption, surface roughness, and wear tests were conducted. It was found that the composition that contains 15% nanofiller composites gave better results in mechanical testing than the composition that contains 10% microfiller composites. Pin-on disc wear test and differential scanning calorimetric thermal test results show that 10% microfiller composites show better outcome results than 15% nanofiller composites. Testing values indicate that lignocellulosic sisal fiber composites with WPCB nano- and microfillers can be substituted for many engineering applications instead of being disposed of in landfills.
... An interesting alternative may be to skip this stage. The main methods of recovering metals from PCBs are: pyrometallurgical methods [13-17] and hydrometallurgical methods [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33]. Pyrometallurgy is a widely used metal recovery group of methods involving mainly the melting of waste materials at high temperatures. ...
... Currently, most electrical and electronic devices, especially mobile phones, contain printed circuit boards (PCBs), which are carriers of many metals, including Cu, Fe, Zn, Sn, Table 1. List of studies on the recovery of metals from PCBs using acids [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33]. ...
The paper presents the possibility of recovering metals from printed circuit boards (PCBs) of spent mobile phones using the hydrometallurgical method. Two-stage leaching of Cu(II), Fe(III), Sn(IV), Zn(II), Ni(II) and Pb(II) with H2SO4 (2 and 5 M) and HNO3 (2 M) with the addition of H2O2 (10 and 30%) and O3 (9 or 15 g/h) was conducted at various process conditions (temperature—313, 333 and 353 K, time—60, 120, 240, 300 min, type and concentration of leaching agent, type and concentration of oxidant, solid–liquid ratio (S/L)), allowing for a high or total metals leaching rate. The use of two leaching stages allows for the preservation of selectivity, separation and recovery of metals: in the first stage of Fe(III), Sn(IV) and in the second stage of the remaining tested metal ions, i.e., Cu(II), Zn(II), Ni(II) and Pb(II). Removing Fe from the tested PCBs’ material at the beginning of the process eliminates the need to use magnetic methods, the purpose of which is to separate magnetic metal particles (ferrous) from non-magnetic (non-ferrous) particles; these procedures involve high operating costs. Since the leaching of Cu(II) ions with sulfuric(VI) acid practically does not occur (less than 1%), this allows for almost complete transfer of these ions into the solution in the second stage of leaching. Moreover, to speed up the process and not generate too many waste solutions, oxidants in the form of hydrogen peroxide and ozone were used. The best degree of leaching of all tested metal ions was obtained when 2 M sulfuric(VI) acid at 353 K was used in the 1st research stage, and 2 M nitric(V) acid and 9 g/h O3 at 298 K in the 2nd stage of leaching, which allowed it to be totally leached 100% of Fe(III), Cu(II), Sn(IV), Zn(II), Ni(II) and 90% Pb(II).
... Methods used for extraction are another contributing factor to the low recovery of the precious metal, as conventional extraction methods like pyrometallurgical and hydrometallurgical processes, which have many limitations, generate hazardous emissions (Khaliq et. al., 2014: Kaya, 2016: Cui and Zhang, 2008 and cyanide used in hydrometallurgical processes is highly toxic (Cui and Zhang, 2008). Several other factors such as temperature, humidity, pH, chemical atmosphere, and mixed composition with other waste items at e-waste dumping sites, also play a role in metal recovery. ...
Disposal of electronic waste (e-waste) has increased many folds post-Covid 2019 (TBRC 2022). E-waste can be an alternate ore to leach out precious metals as compared to conventional techniques, but only a few regions like Europe (42% recycling rate) and Asia (12% recycling rate) are accountable for effective recycling at the global scale; others majorly follow unsafe strategies to recycle e-waste (Cui and Zhang 2008), releasing hazardous contents into the environment and leading to many complications (Loganathan and Masunaga 2015). This chapter gives insights on various methods used for leaching metals from e-waste, their limitations, and biorecovery using microorganisms, as an alternative strategy to extract valuable metals such as gold, copper, palladium, silver, iron, and platinum. Mechanisms of microbial leaching with examples of bacteria used are also discussed. Interventions of biotechnological approaches, like developing new strains with high microbial leaching efficiency, are also suggested for sustainable development.
... At the end of the product life, these REE-containing equipment or units, such as permanent magnets and fluorescent lamps, are known as electronic waste or e-waste [16,17]. E-waste consists of six categories, namely temperature exchange equipment, screens and monitors, lamps, large equipment (e.g., washing machines and printing machines), small equipment, and small IT and telecommunication equipment [18]. ...
Rare earth elements (REEs) are key ingredients in many advanced materials used in energy, military, transportation, and communication applications. However, the prevailing geopolitical dynamics and the rising demand for REEs have rendered the reliance on primary REE resources susceptible to future supply disruptions, posing a substantial risk to the availability of these elements for numerous applications. Therefore, it is imperative to undertake substantial initiatives in the extraction of REEs from secondary sources on a large scale to ensure the resilience of the supply chain. Permanent magnets, lighting phosphors, and nickel-metal hydride (NiMH) batteries are among the secondary sources with high potential for sustainable REE extraction. This review assesses the extraction potential of REEs from the aforementioned three secondary sources and their leaching kinetics and thermodynamics aspects. More importantly, state-of-the-art different existing kinetic models employed in rare earth (RE) leaching were well discussed for a better understanding of the REE leaching reactions. Furthermore, the optimized leaching parameters related to this kinetics were described, and various RE recovery methods were comprehensively summarized. These processes facilitate to managing one of the fastest-growing solid waste streams by minimizing environmental impacts and producing critical metals, including REEs via circular economy approaches. The recovery of REEs from secondary sources aligns with numerous United Nations Sustainable Development Goals (SDGs), particularly in the renewable energy sector for climate change mitigation. Consequently, this trash-to-treasure urban mining concept to transforming e-waste into a valuable resource for REE recovery emerges as a pivotal element within the REE industry.
... Various global processes, including those implemented by Umicore (Belgium), Outotec (Finland), Boliden Rönnskär (Sweden), and Aurubis (Germany), have reported the extraction of these metals at different process stages. For instance, zinc, lead, and tin are primarily collected in the flue dust during copper smelting and copper blister conversion, while nickel is typically recovered as crude Ni-sulfate in copper slimes during the copper electrolysis (Chagnes 2016;Khaliq et al. 2014). ...
... The presence of silver (195 ppm) and gold (19.24 ppm) in PSLF indicate a significant resource potential for extraction, with concentrations 2.7 times higher for silver (72 ppm of Ag) (Swinkels et al. 2021)) and 962 times higher for gold (0.02 ppm of Au) (Adams, 2016) compared to major commercial ores used for primary extraction of these precious metals. Similarly, PSLF contains precious metals at concentrations similar to the average WEEE scraps, ranging from 20 to 30 ppm for gold and 200-3000 ppm for silver (Chagnes 2016;Khaliq et al. 2014;Zhang et al. 2017). ...
The surge in Waste Electrical and Electronic Equipment (WEEE) generation, reaching 53.6 million metric tons (Mt) in 2019, demands efficient recycling solutions. This study focuses on the Shredder Light Fraction (SLF), a material stream derived from the mechanical pre-processing of WEEE, which is considered "municipal waste". SLF constitutes 4.2% of the output material and is rich in metals like copper, tin, lead, zinc, silver, and gold. Pyrolysis treatment was applied to SLF, enabling recyclability. Both batch and continuous setups were employed for materials flow analysis and technical evaluation of the resource potential. The research evaluates the impact of pyrolysis technology on solid fraction metal content and pyrolysis gas/oil energy potential. Scaling up the process addressed material heterogeneity and increased the reliability of the obtained results. An innovative pyrometallurgical extraction approach was suggested, to recover valuable metals in SLF which otherwise could be lost via energy recovery methods. The resulting solid product after pyrolysis showed enriched concentrations of copper, zinc, lead, and precious metals with concentrations acceptable for industrial use. Additionally, it displayed reduced mass and diminished hazardous constituents. The non-condensable gas, rich in hydrogen, carbon monoxide, and methane, exhibited potential as an alternative energy source or reducing agent in the metallurgical sector. This research advances metal recycling from SLF, offering valuable insights for environmental impact miti-gation as waste was transformed into a valuable by-product for potential use in the copper industry.
