How to extract precious metal platinum from waste

Extracting platinum from waste, particularly from electronic waste (e-waste), automotive catalytic converters, and industrial byproducts, involves a series of complex processes. Platinum is highly valuable and is used in various applications such as catalytic converters, jewelry, and industrial processes.

1. Collection and Sorting
   Collecting Waste Materials: Gather e-waste components such as circuit boards, catalytic converters, or other electronic devices that contain platinum.
   Sorting: Separate items likely to contain platinum, such as platinum-coated components in catalytic converters and certain connectors in electronics.
2. Mechanical Processing
   Shredding: Break down the waste into smaller pieces to expose the internal components containing platinum.
   Grinding: Further grind the material into fine particles to increase surface area and aid in subsequent chemical processing.
   Separation: Use physical methods like magnetic separation to remove ferrous materials, and eddy current separation to isolate non-ferrous metals.
3. Chemical Leaching
   Dissolving Platinum:
   Aqua Regia Solution: Use a mixture of hydrochloric acid (HCl) and nitric acid (HNO₃) in a 3:1 ratio to create aqua regia. This strong acid mixture is capable of dissolving platinum and other precious metals such as gold and palladium.
   Reaction: Pt+4HNO3​+6HCl→H2​[PtCl6​]+4NO2​+4H2​O

This process dissolves platinum into a soluble platinum chloride complex, while other metals may also dissolve.

4. Precipitation of Platinum
   Selective Precipitation: Add a reducing agent (e.g., ammonium chloride or sodium chloride) to the leach solution to selectively precipitate platinum from the dissolved mixture.
   Formation of Platinum Precipitate: Platinum precipitates as platinum chloride (PtCl₂) or as a solid platinum powder, which can then be filtered and isolated.
5. Refining Platinum
   Thermal Treatment: Heat the platinum powder in a furnace to remove remaining impurities and form refined platinum.
   Electrorefining (Optional): For higher purity, use electrorefining. In this process, the crude platinum is dissolved in an electrolyte, and an electric current is passed through the solution to deposit pure platinum onto the cathode.
6. Recovery of Byproducts
   Recovery of Other Metals: The remaining solution or waste material can be treated further to recover other valuable metals like gold, palladium, and rhodium. This is typically done using similar leaching, precipitation, and refining methods.
7. Final Products
   Pure Platinum: After refining, platinum is available in high purity, typically as ingots, powder, or metal bars for use in industrial applications.
   Platinum Alloys: The purified platinum can also be alloyed with other metals for use in jewelry, automotive applications, or electronics.
8. Environmental and Safety Considerations
   Protective Gear: Always wear protective equipment, including gloves, goggles, and masks, especially when handling acids like aqua regia and during high-temperature processing.
   Proper Ventilation: Ensure good ventilation when using chemicals such as nitric acid, hydrochloric acid, and aqua regia, as they release toxic gases (e.g., nitrogen dioxide).
   Waste Disposal: Follow local regulations for disposing of hazardous materials and e-waste. Proper treatment of the byproducts and residual chemicals is essential to prevent environmental contamination.
   Applications of Recovered Platinum
   Catalytic Converters: Platinum is widely used in catalytic converters to reduce harmful emissions in vehicles.
   Jewelry: Platinum is used in fine jewelry and watches due to its durability and rarity.
   Electronics: Platinum is used in electronics for components like resistors and hard disk drives.
   Industrial Applications: Platinum is used as a catalyst in chemical reactions and in various industrial processes, including petroleum refining and hydrogen production.
   Conclusion
   Extracting platinum from waste requires specialized knowledge, equipment, and safety precautions. While the process can be complex, it is highly rewarding given the high value of platinum. This process is typically carried out in industrial recycling facilities that have the necessary infrastructure to handle hazardous chemicals and perform refining procedures.