Complete Guide to Recovering Gold from IC Chips: Wet Ashing Method and Aqua Regia Purification

Recovering Gold from IC Chips Using Wet Ashing and Aqua Regia

In this blog post, we will discuss the process of recovering gold from IC chips using the wet ashing method and purifying it using aqua regia. These processes can be a cost-effective way to obtain high-quality gold.

Wet Ashing Method

The wet ashing method involves dissolving the black plastic of the IC chip in concentrated sulfuric acid to reveal the gold wire inside. Here are the step-by-step instructions:

1. Begin by collecting around 400 grams of IC chips in an aluminum saucepan.

2. Pour two liters of concentrated sulfuric acid into the saucepan.

3. Heat the mixture on a stove at a temperature of 100 degrees Celsius.

4. Use a stick to stir the mixture occasionally, to prevent bubbles from rising and the acid from spilling.

5. If needed, add another 300ml of sulfuric acid to the mixture.

6. Allow the mixture to heat for an hour, until the black plastic of the IC chips is fully dissolved, and the gold wire inside is visible.

7. Let the acid in the saucepan cool down to room temperature.

8. Once the acid has cooled, carefully pour the dark, thick, IC plastic-dissolved sulfuric acid into another waste bucket. Be careful to ensure that the gold wire of the IC chip does not float.

9. Wash the gold wires five to six times with clean water to remove any remaining impurities.

10. Once the gold wires are clean, dry them with a soft cloth or towel.

Additional Instructions:

11. Use a fume hood or perform the procedure in a well-ventilated area to avoid inhaling harmful sulfuric acid fumes.

12. Always wear appropriate protective gear, such as gloves and goggles, when handling concentrated sulfuric acid.

13. Dispose of the waste sulfuric acid and dissolved IC plastic in accordance with local regulations.

Aqua Regia Process

After completing the wet ashing process, the gold wire obtained may not be entirely pure. Therefore, to purify the gold wire, it is necessary to use a process called aqua regia. Here are the steps:

1. Prepare aqua regia by mixing three parts of hydrochloric acid and one part of nitric acid in a glass container.

2. Put the gold wire in a glass beaker and add enough aqua regia to cover it.

3. Heat the beaker on a hot plate, while stirring the mixture occasionally.

4. Once the gold wire is fully dissolved, let the mixture cool down to room temperature.

5. Add a reducing agent, such as sodium metabisulfite or oxalic acid, to the mixture to precipitate the gold.

6. Filter the mixture to separate the gold precipitate from the solution.

7. Wash the gold precipitate several times with distilled water to remove any remaining impurities.

8. Dry the purified gold precipitate using a drying oven or a hairdryer.

Conclusion

Recovering gold from IC chips using the wet ashing method and purifying it using aqua regia can be a cost-effective way to obtain high-quality gold. However, it is crucial to follow proper safety measures when handling chemicals such as concentrated sulfuric acid and aqua regia. It is also important to dispose of the waste chemicals in accordance with local regulations.