scholarly journals Metal Extraction and Recovery from Mobile Phone PCBs by a Combination of Bioleaching and Precipitation Processes

Minerals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1004
Author(s):  
Arrate Santaolalla ◽  
Piet N. L. Lens ◽  
Astrid Barona ◽  
Naiara Rojo ◽  
Ainhoa Ocio ◽  
...  
Keyword(s):  
Mobile Phone ◽  
Printed Circuit Boards ◽  
Metal Extraction ◽  
Copper Extraction ◽  
Secondary Source ◽  
Circuit Boards ◽  
Metal Recycling ◽  
Effective Removal ◽  
Valuable Metals ◽  
Synthetic Solution

Bearing in mind the metal rich composition of printed circuit boards (PCBs), this material represents a secondary source of valuable metals and offers an entrepreneurial opportunity in the metal sales market. Based on the ability of microorganisms to regenerate and produce the chemical oxidants that are responsible for metal leaching, bioleaching has become an efficient and affordable alternative to conventional metal recycling technologies, although further research is still necessary before industrial implementation. This study focuses on the recovery of metals contained in mobile phone PCBs through a combined process. Two different PCB pre-treatments were evaluated: grinding the whole piece and removing the epoxy cover from the piece without grinding. The benefit of A. ferrooxidans activity on the metal solubilization rate was analyzed. Additional chemical leaching assays were also conducted for comparison purposes and the reagents ferric iron (Fe3+) and sulfuric acid (H2SO4) were selected for these experiments. The copper extraction results obtained in Fe3+ experiments with and without bacteria (A. ferrooxidans) were similar after 260 h of operation, indicating the need for alternative strategies to ensure a controlled and continuous metal biodissolution rate. The contribution of H2SO4 to the leaching processes for copper and nickel was almost negligible during the first 50 h, and more significant thereafter. The recovered metals were precipitated from a synthetic solution simulating a real ferric leaching by adding sodium hydroxide (NaOH) and sodium sulfide (Na2S). The combination of both precipitants allowed an effective removal of metals from the leachate.

scholarly journals Food Waste-Assisted Metal Extraction from Printed Circuit Boards: The Aspergillus niger Route

2021 ◽  
Vol 9 (5) ◽  
pp. 895
Author(s):  
Carlotta Alias ◽  
Daniela Bulgari ◽  
Fabjola Bilo ◽  
Laura Borgese ◽  
Alessandra Gianoncelli ◽  
...  
Keyword(s):  
Solid State ◽  
Aspergillus Niger ◽  
Food Waste ◽  
Solid State Fermentation ◽  
Printed Circuit Boards ◽  
Electronic Waste ◽  
Metal Extraction ◽  
Circuit Boards ◽  
Printed Circuit ◽  
Waste Printed Circuit Boards

A low-energy paradigm was adopted for sustainable, affordable, and effective urban waste valorization. Here a new, eco-designed, solid-state fermentation process is presented to obtain some useful bio-products by recycling of different wastes. Urban food waste and scraps from trimmings were used as a substrate for the production of citric acid (CA) by solid state fermentation of Aspergillus niger NRRL 334, with a yield of 20.50 mg of CA per gram of substrate. The acid solution was used to extract metals from waste printed circuit boards (WPCBs), one of the most common electronic waste. The leaching activity of the biological solution is comparable to a commercial CA one. Sn and Fe were the most leached metals (404.09 and 67.99 mg/L, respectively), followed by Ni and Zn (4.55 and 1.92 mg/L) without any pre-treatments as usually performed. Commercial CA extracted Fe more efficiently than the organic one (123.46 vs. 67.99 mg/L); vice versa, biological organic CA recovered Ni better than commercial CA (4.55 vs. 1.54 mg/L). This is the first approach that allows the extraction of metals from WPCBs through CA produced by A. niger directly grown on waste material without any sugar supplement. This “green” process could be an alternative for the recovery of valuable metals such as Fe, Pb, and Ni from electronic waste.

Supercritical CO2-induced alteration of a polymer–metal matrix and selective extraction of valuable metals from waste printed circuit boards

2020 ◽  
Vol 22 (20) ◽  
pp. 7080-7092
Author(s):  
Peng Peng ◽  
Ah-Hyung Alissa Park
Keyword(s):  
Metal Matrix ◽  
Supercritical Co2 ◽  
Printed Circuit Boards ◽  
Selective Extraction ◽  
Circuit Boards ◽  
Printed Circuit ◽  
Waste Printed Circuit Boards ◽  
Valuable Metals ◽  
Polymer Metal

Supercritical CO2-induced treatment of heterogeneous waste printed circuit boards resulted in selective recoveries of Au, Ni and Cu.

scholarly journals Extraction of Copper and Zinc from Waste Printed Circuit Boards

Recycling ◽  
2019 ◽  
Vol 4 (3) ◽  
pp. 36 ◽  
Author(s):  
Ayorinde Emmanuel Ajiboye ◽  
Folorunsho Emmanuel Olasehinde ◽  
Ojo Albert Adebayo ◽  
Olubode John Ajayi ◽  
Malay Kumar Ghosh ◽  
...  
Keyword(s):  
Printed Circuit Boards ◽  
Selective Extraction ◽  
Leach Solution ◽  
Economic Resources ◽  
Circuit Boards ◽  
Printed Circuit ◽  
Waste Printed Circuit Boards ◽  
Valuable Metals ◽  
Extraction Selectivity ◽  
Cu And Zn

The recovery of valuable metals from waste printed circuit boards (WPCBs) is crucial in order to harness their economic resources, and prevents potential environmental contamination. However, selective extraction of Cu and Zn, and the co-extraction of other metals as impurities at ambient temperature using selected lixiviants such as HCl, H2SO4, HNO3, trifluoromethanesulfonic acid (TFMS), NaOH, and mixtures of NaCl and CuCl2 was studied. It is shown that the extraction efficiencies of all the metals increased with increases in lixiviant concentrations. High selectivity of Cu and Zn toward Fe were achieved in dilute H2SO4, HNO3, TFMS, and 0.5 M NaCl + 0.1 M CuCl2, and low dissolution of Pb (<5%) was observed in all H2SO4 lixiviants. Almost 100% Zn extraction using NaOH lixiviants without trace of other metals was achieved. Therefore, 0.5 M NaCl + 0.5 M CuCl2, 1.0 M HNO3, 0.5 M H2SO4, and 1.0 M TFMS showed high extraction selectivity toward Cu and Zn with low chemical consumption, and produced pregnant leach solution rich in Cu and Zn, as well as residue containing Fe, Ni, and other metals.

scholarly journals Biodismantling, a Novel Application of Bioleaching in Recycling of Electronic Wastes

Recycling ◽  
2020 ◽  
Vol 5 (3) ◽  
pp. 22
Author(s):  
Benjamin Monneron-Enaud ◽  
Oliver Wiche ◽  
Michael Schlömann
Keyword(s):  
Integrated Circuits ◽  
Printed Circuit Boards ◽  
Raw Materials ◽  
Iron Sulfate ◽  
Circuit Boards ◽  
Copper Leaching ◽  
Valuable Metals ◽  
A New Technique ◽  
Abiotic Controls ◽  
Processing Steps

Electronic components (EC) from waste electrical and electronic equipment (WEEE) such as resistors, capacitors, diodes and integrated circuits are a subassembly of printed circuit boards (PCB). They contain a variety of economically valuable elements e.g., tantalum, palladium, gold, and rare earth elements. However, until recently there has been no systematic dismantling and recycling of the EC to satisfy the demand for raw materials. A problem connected with the recycling of the EC is the removal of the components (dismantling) in order to recover the elements in later processing steps. The aim of the present study was to develop a new technique of dismantling using bioleaching technology to lower costs and environmental impact. In triplicate batch experiments, used PCBs were treated by bioleaching using an iron-oxidizing mixed culture largely dominated by Acidithiobacillus ferrooxidans strains supplemented with 20 mM ferrous iron sulfate at pH 1.8 and 30 °C for 20 days. Abiotic controls were treated by similar conditions in two different variations: 20 mM of Fe2+ and 15 mM of Fe3+. After 20 days, successful dismantling was obtained in both the bioleaching and the Fe3+ control batch. The control with Fe2+ did not show a significant effect. The bioleaching condition presented a lower rate of dismantling which can partially be explained by a constantly higher redox potential leading to a competition of solder leaching and copper leaching from the printed copper wires. The results showed that biodismantling—dismantling using bioleaching—is possible and can be a new unit operation of the recycling process to maximize the recovery of valuable metals from PCBs.

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