Designing a sustainable and eco-friendly process for the extraction and recovery of valuable metals from electronic waste involves several steps. Here's a possible step-by-step process:1. Collection and sorting of electronic waste: - Collect electronic waste from various sources such as households, businesses, and recycling centers. - Sort the waste based on the type of electronic device, such as computers, mobile phones, and televisions. - Dismantle the devices to separate the components containing valuable metals, such as printed circuit boards PCBs , connectors, and wires.2. Size reduction and mechanical separation: - Shred the components into small pieces to increase the surface area for further processing. - Use mechanical separation techniques such as magnetic separation, air classification, and sieving to separate different materials, including metals, plastics, and glass.3. Pyrolysis: - Heat the shredded components in the absence of oxygen to break down the organic materials, such as plastics and resins, into gases, oil, and char. - The remaining solid residue will contain a higher concentration of metals, making it easier to extract the valuable metals in the subsequent steps.4. Leaching: - Use eco-friendly leaching agents, such as citric acid, ascorbic acid, or glycine, to dissolve the metals from the solid residue. - Adjust the pH, temperature, and concentration of the leaching agent to optimize the extraction process.5. Metal recovery: - Use precipitation, solvent extraction, or ion exchange methods to selectively recover the valuable metals from the leachate. - For example, add a precipitating agent to the leachate to selectively precipitate gold, silver, or copper, which can then be filtered and collected. - Alternatively, use a selective solvent or ion exchange resin to extract the target metal ions from the leachate, followed by stripping and recovery of the metal.6. Purification and refining: - Further purify the recovered metals using electrorefining, pyrometallurgical refining, or hydrometallurgical refining methods, depending on the specific metal and its desired purity level. - For example, use the Wohlwill process electrorefining to obtain high-purity gold, or the electrolytic refining process to obtain high-purity copper.7. Waste treatment and disposal: - Treat the remaining waste materials, such as leachate, sludge, and off-gases, using appropriate methods to minimize environmental impact. - For example, neutralize the acidic leachate with alkaline substances, and treat the off-gases using scrubbers or filters to remove pollutants. - Dispose of the treated waste materials in an environmentally responsible manner, such as landfilling or incineration, following local regulations and guidelines.8. Recycling and reuse: - Recycle and reuse the recovered metals in the manufacturing of new electronic devices or other applications, thereby reducing the demand for virgin metals and contributing to a circular economy.By following these steps, it is possible to design a sustainable and eco-friendly process for the extraction and recovery of valuable metals from electronic waste.