How to recycle gold from cpu computer scrap. value of gold in cpu ceramic processors pins chip.

Recovering Gold from CPU Computers

Key Concepts: CPU gold recovery, nitric acid pre-treatment, aqua regia dissolution, urea acidity reduction, sodium metabisulfite precipitation, gold refining, induction heating.

1. Introduction to Gold in CPUs

• CPUs (Central Processing Units) contain gold in their pins and circuit board connectors due to gold's excellent conductivity and resistance to corrosion.
• The video focuses on recovering gold from older CPUs, specifically mentioning models like 486 and Pentium Pro.
• Ceramic CPUs generally contain more gold than other types.
• The presenter emphasizes that "most technology uses gold to drive."

2. Pre-treatment with Nitric Acid

• Purpose: To remove base metals (like lead solder) and reduce the amount of non-gold material before dissolving the gold.
• Process:
  • Soak the CPU components (pins, gold-plated parts) in nitric acid (HNO3).
  • The video uses 2000 ml of water and 1000 ml of nitric acid.
  • Leave the components in the nitric acid for approximately two weeks.
  • The nitric acid dissolves the lead solder, causing the gold-plated pins to detach.
  • The water will turn green as other metals dissolve.
• Rationale: The presenter argues that skipping this step results in too many other metals contaminating the aqua regia solution, leading to lower gold purity. "Nitric acid is a good gold sorter for gold alloys and gold-plated."
• The presenter soaks the CPU components in nitric acid for one month to separate the gold overlay under the die chip.

3. Aqua Regia Dissolution

• Definition: Aqua regia is a highly corrosive mixture of nitric acid (HNO3) and hydrochloric acid (HCl), optimally in a molar ratio of 1:3.
• Preparation: Mix one part nitric acid with three parts hydrochloric acid.
• Process:
  • Slowly pour the aqua regia into the pre-treated CPU components.
  • Safety: The presenter emphasizes the importance of using protective equipment, including acid-resistant gloves and a gas mask, due to the hazardous nature of the chemicals.
• Purpose: Aqua regia dissolves the gold, forming a gold chloride solution.

4. Neutralizing Excess Acidity with Urea

• Purpose: To reduce the acidity of the gold-containing solution before precipitation.
• Process: Add urea to the solution until it reaches a saturation point (i.e., no more urea dissolves).
• Rationale: Reducing acidity is crucial for efficient gold precipitation with sodium metabisulfite. The presenter states, "Urea reduces the acid that we put over. Urea is not a precipitate of gold. The gold is precipitated well the acidity will be less."
• The presenter notes that if the aqua regia is used in appropriate quantities, urea may not be necessary.

5. Gold Precipitation with Sodium Metabisulfite

• Reagent: Sodium metabisulfite (Na2S2O5)
• Process:
  • Gradually add sodium metabisulfite to the solution.
  • Stop adding when the solution reaches saturation.
  • Allow the solution to sit for 2-4 hours, allowing the gold to precipitate as a brown sludge.
• Separation: Carefully pour off the liquid, leaving the gold sludge at the bottom. The presenter warns that "the Hwang slides will flow with water" if not careful.

6. Washing and Drying the Gold Sludge

• Process:
  • Wash the gold sludge three times with hot water to remove residual chemicals.
  • Dry the gold powder using a hot air blower.

7. Melting the Gold Powder

• Equipment: Induction heater and graphite crucible.
• Process:
  • Place the gold powder in the graphite crucible.
  • Use the induction heater to melt the gold powder into a solid lump.
• Advantages of Induction Heating: Convenient, quick, and easy.

8. Final Result and Weighing

• The video showcases the final gold lump obtained from the process.
• The weight of the recovered gold is 6.7 grams.

9. Conclusion

• The video provides a detailed, step-by-step guide on recovering gold from CPU computers.
• It emphasizes the importance of pre-treatment with nitric acid, careful use of aqua regia, acidity reduction with urea, and proper precipitation with sodium metabisulfite.
• The presenter encourages viewers to share their own methods and insights in the comments.