Waste Cellphones Research Articles

Flower pollination algorithm with ring topology for multi-solution spaces to solve the disassembly line balancing problem

Abstract The Disassembly Line Balancing Problem (DLBP) is of significant importance in the product recycling process. However, existing DLBP research have primarily proposed improved optimization algorithms for single solution space. To provide decision makers with more efficient disassembly solutions, this paper chooses three classical layouts (straight, U-shaped, and parallel) to broaden the solution space and expands an incomplete DLBP with multi-solution spaces (DLBP-MS). By employing the strategy of incomplete disassembly, only the essential components are retained. In DLBP-MS, the disassembly information from used products is processed and imported into the three types of disassembly spaces to be solved and compared to find suitable disassembly solutions. And a multi-objective mathematical model is developed, this includes factors such as workstation count, free time, disassembly smoothness index, carbon emission, and disassembly revenue. The part constraints are established based on directed graphs, and the encoding and decoding methods for multi-solution spaces disassembly sequences in the random incomplete case are designed respectively. A ring topology based flower pollination algorithm (RTFPA) is introduced to effectively address the DLBP-MS. The solution set obtained during the iterative process is divided into subsets based on the congestion level and the overall diversity is preserved by internal optimization of these subsets. After that, the RTFPA is applied to the DLBP-MS of waste cell phones and computers. The improvement of the algorithm's optimization ability under different solution spaces is verified by comparing the results with those obtained from four other algorithms.

Multi-Metal Mining from Waste Cell Phone Printed Circuit Boards using Lixiviant Produced by a Consortium of Acidophilic Iron Oxidizers

Recently electronic waste (e-waste) includes the fastest growing waste stream in the world. Nevertheless, it also contains about 40 different elements of the periodic table; hence it is a significant metal source. Generally, e-waste recycling is done by the pyrometallurgy and/or hydrometallurgy method. However, the use of microorganisms in hydrometallurgy called bioleaching is a good alternative for eco-friendly and cost-effective recycling of e-waste and recover metals. Leptospirillum-dominated consortium was used to generate ferric iron lixiviant by oxidizing ferrous iron. The resulting lixiviant was used for bioleaching of metals from waste cell phone printed circuit boards (WPCBs). The pretreatment of pulverized WPCB (p-WPCB) and unpulverized WPCB (up-WPCB) was done using 2 M NaOH to see the effect of pretreatment on metal extraction. Moreover, the effect of maintenance of pH of the system was also checked. The controlling of pH of the system to 2.0 ± 0.1 showed enhancement of Cu, Zn, and Ni solubilization. The highest solubilization of copper was 96.86%, which was achieved with pretreated up-WPCB; zinc was 90.69% with pretreated p-WPCB, whereas nickel was 93.65% with untreated up-WPCB. Ours is the first report for extraction of copper, zinc, and nickel from unpulverized mobile phone WPCBs at high pulp density. The solubilization of metals achieved with 100 g/L pulp density provides a promising indication to scale up the process.

The brighter side of e-waste-a rich secondary source of metal.

This article details the electronic waste (e-waste) generation, their composition, health, and environment hazards, and legal rules for disposal as well as their significance as a potential secondary source of metals and other components. Moreover, valuable metal extraction technologies from the e-waste are reviewed in general and waste cell phones in particular. E-waste is nowadays preferentially used for recovery of metals mainly from printed circuit boards (PCBs). Different techniques, namely pyrometallurgy, hydrometallurgy, and biohydrometallurgy used for metal extraction from e-waste are swotted. The economic and environmental valuation features of these technologies are also included. Compared to other methods, biohydrometallurgy is the method of choice, as in it natural components like air and water are used, has low operating and maintenance cost, and operate at ambient temperature and pressure. Microbial aspects of metal extraction from e-waste are summarized.

Analyzing present and future availability of critical high-tech minerals in waste cellphones: A case study of India

Critical high-tech minerals (CHTMs) are raw materials that are essential for a future clean-energy transition and the manufacture of high-end products. Cellphones, one of the fastest growing electronic products, contain various CHTMs. Since 2019, India has surpassed the United States to become the second largest smartphone market in the world. An increasing and alarming number of excessive waste cellphones will be generated in India in the near future. In this study, the dynamic material flow analysis approach and the Weibull distribution are adopted to analyze the volumes of accumulated waste cellphones and the contained CHTMs based on the differentiation between smartphones and feature phones in India. Moreover, a market supply model is adopted to predict the future trends of CHTMs in waste cellphones. The results show a general upward tendency of waste cellphone volume in India, which indicates that various CHTMs contained in cellphone waste can be properly reused or recycled. Future implications based on the analysis results are provided for efficient cellphone management in India.

An Evaluation of Potential Yield of Indium Recycled from Waste Mobile Phone in China

In recent years, users replace their mobile phone more and more frequently, therefore, the number of waste mobile phones has been increasing year by year. In 2014, the number was more than 1 billion units. Indium, that has unique optical transparency and electrical conduction properties, is a necessary element in the screen of mobile phone. The potential yield of indium recycled from waste mobile phone is considerable. Recycling indium from waste mobile phones can alleviate the constraints of indium resources while gaining great economic benefit. However, there is no relevant research work to evaluate the potential yield of indium in the waste cell phone. This paper explores the main factors that constraint the efficiency of recycling by predicting potential yield of indium recycled from waste mobile phone, and puts forward the corresponding policy recommendations. The results are based on the Logistic model and Stock-base model and a survey. The results show that the potential yield of indium recycled from waste mobile phone from 2015 to 2035 will increase from 8.7 tonnes to 10.2 tonnes in China. However, the recovery rate of waste mobile phone is very low, the actual available amount is far lower than the potential yield of indium. The main factors that constrain the efficiency of recycling are: (1) it is difficult to guarantee information security; (2) the existing recycling system is not perfect; (3) the technology of recycling indium needs to be improved.

폐 PCBs의 미분쇄 공정 적용에 따른 유가금속 분포 특성 및 금속 침출 향상에 관한 연구

The main objective of this study is to recovery valuable metals with metal particle size distributions in waste cell phone PCBs(Printed Circuit Boards) by means of pulverization and nitric acid process. The particle size classifier also was evaluated by specific metal contents. The PCBs were pulverized by a fine pulverizer. The particle sizes were classified by 5 different sizes which were PcS1(0.2 mm below), PcS2(0.20~0.51 mm), PcS3(0.51~1.09 mm), PcS4(1.09~2.00 mm) and PcS5(2.00 mm above). Non-magnetic metals in the grinding particles were separated by a hand magnetic. And then, Cu, Co and Ni were separated by 3M nitric acid. Particle diameter of PCBs were 0.388~0.402 mm after the fine pulverizer. The sorting coefficient were 0.403~0.481. The highest metal content in PcS1. And the bigger particle diameter, the lower the valuable metals exist. The recovery rate of the valuable metals increases in smaller particle diameter with same leaching conditions. For further work, it could improve to recovery of the valuable metals effectively by means of individual treatment, multistage leaching and different leaching solvents.

Initial Studies about Gold Leaching from Printed Circuit Boards (PCB's) of Waste Cell Phones

Excessive consumption of mobile phones, a decrease in their life time and, therefore, an increase in the generation of this type of electronic scrap, is noted in recent years. Printed circuit boards (PCB's) from waste cell phones are attractive resources because of the valuable metals Cu, Au, Ag, Pd they possess, but at the same time dangerous due to their content of heavy metals. The treatment of these boards is desirable from an economic and environmental perspective.In this paper we inform the results achieved on laboratory leaching of gold contained in PCB's from cell phones. The reagents used were ammonium thiosulfate in basic medium and thiourea in sulfuric acid solution. Prior to gold leaching, the plates were subjected to grinding to reduce their size to less than 2mm and to an oxidizing leaching in sulfuric acid solution to separate the copper. The conditions studied in the leaching test were: thiosulfate molar concentration between 0.08M and 0.12M and ammonium hydroxide from 0.1M to 0.2M, temperature of 20° C, pH = 10.5 and 15mM of cupric ion. In thiourea leaching, gold dissolution was studied by varying the concentration of the reagent between 20g/l to 28g/l. The results indicate that, under the conditions studied, ammonium thiosulfate is a more effective reagent for the dissolution of gold than thiourea. The gold dissolution values achieved were up 70% for thiosulfate and no greater than 40% for thiourea.