To design an efficient and environmentally friendly system for recovering valuable metals like gold, silver, and platinum from electronic waste e-waste , we can follow these steps:1. Collection and sorting of e-waste: The first step is to collect and sort the e-waste according to the type of electronic devices and components. This will help in identifying the materials that contain valuable metals and separating them from other waste materials.2. Mechanical processing: The sorted e-waste should be subjected to mechanical processes like shredding, crushing, and grinding to break down the components into smaller particles. This will increase the surface area and make it easier to extract the metals.3. Pyrometallurgical processing optional : In some cases, pyrometallurgical processes like smelting can be used to separate the metals from the e-waste. However, this step should be carried out in a controlled environment with proper waste gas treatment systems to prevent air pollution.4. Hydrometallurgical processing: The crushed e-waste particles can be subjected to hydrometallurgical processes like leaching, precipitation, and solvent extraction to selectively dissolve and recover the valuable metals. The choice of leaching agents should be environmentally friendly, such as using citric acid, thiourea, or thiosulfate instead of toxic cyanide or strong acids.5. Electrochemical processing: After the metals have been dissolved and separated, they can be recovered using electrochemical processes like electrowinning or electrorefining. These processes involve passing an electric current through the solution to deposit the metals onto a cathode.6. Waste treatment and disposal: The remaining waste materials should be treated and disposed of in an environmentally friendly manner. This may involve neutralizing any hazardous chemicals, solidifying the waste, and disposing of it in a secure landfill or recycling it for other uses.7. Monitoring and control: The entire process should be monitored and controlled to ensure that it is efficient, safe, and environmentally friendly. This may involve using sensors and control systems to monitor the emissions, waste generation, and energy consumption, as well as implementing best practices for waste management and pollution prevention.By following these steps, we can design a system that efficiently recovers valuable metals from e-waste while minimizing the environmental impact. This will not only help in conserving natural resources but also reduce the environmental and health risks associated with improper e-waste disposal.