You might want to make ends meet by refining your gold at home, or you might be a jeweler who wants to refine gold itself. There are many ways to refine gold on a small scale as long as you take safety precautions. This article will teach you how to refine gold using the aqua regia method (royal water: mixture of hydrochloric acid and nitric acid).
Part 1 of 6: smelting gold
Step 1. Place your gold jewelry or nugget in a crucible
Most crucibles are made from graphite, which allows them to withstand the melting of the metal inside.
Step 2. Place the crucible on a fire resistant surface
Step 3. Heat the gold with an acetylene torch
Apply the flame to the gold until it is completely melted.
Step 4. Use pliers to grab the crucible
Step 5. Divide the gold into small pieces and let them harden
If you are refining small jewelry like rings then you can just melt it down without having to break it down into smaller parts.
Part 2 of 6: Add the acid
Step 1. Choose a suitable container
- You will need a container with a capacity of 300 milliliters for every 30 grams of gold to be refined.
- Use heavy-duty containers such as heavy-duty plastic buckets or pyrex (borosilicate glass) jars.
Step 2. Wear protection
- Put on a pair of rubber gloves to protect your hands from the acid. Wear them to handle all the chemicals mentioned in this article.
- Put on a rubber apron to protect your clothes
- Put on protective goggles.
- Plan to wear a mask to protect yourself from harmful inhalations.
Step 3. Put the container outside in a well ventilated area
The acid reactions of the aqua regia process cause strong toxic fumes which are very dangerous!
Step 4. Pour 30 milliliters of nitric acid per 30 grams of gold in your container
Let the acid attack the gold for 30 minutes.
Step 5. Add 120 milliliters of hydrochloric acid or muriatic acid per 30 grams of gold, to the container
Let sit overnight. This is the time it takes for the fumes to dissipate.
Step 6. Pour the acid into another larger container
- Make sure you don't put any alongside or on the gold. It would contaminate him.
- The acid should be a transparent emerald green color. If the color is cloudy, you should run the acid through a Buchner funnel to filter it.
Part 3 of 6: Add urea and precipitant
Step 1. Heat 1 liter of water and add 30 grams of urea to the water
Let heat until boiling.
Step 2. Gradually add the water / urea-acid mixture
- The acidic mixture will foam when the water is mixed with the urea. Take it slowly so that the acid does not spill out of the container.
- The water-urea mixture neutralizes the nitric acid in your solution, but not the hydrochloric acid.
Step 3. Add a precipitant to a quart of boiling water following the manufacturer's instructions
- In general, add 30 grams of precipitant for 30 grams of gold to be refined.
- Avoid getting your face too close to the container. The smell is very strong and pungent.
Step 4. Slowly add the water / acid precipitating solution
- The acid will turn an opaque brown color, this is actually due to the separation of the gold particles.
- Let stand for 30 minutes to allow the precipitating solution to act on the gold particles.
Part 4 of 6: Testing the acid to dissolve
Step 1. Immerse a mixing stick in the acid solution
Step 2. Pour a drop of the solution on a paper towel
Step 3. Pour a drop of metal detection fluid over the drop of acid
If it turns purple, you need to let the acid work longer before you get rid of it.
Step 4. As soon as the acid is free from any gold particles, pour it into a clear container
- The acid should be amber with a mud-like deposit on the bottom of the container.
- Do not get rid of the mud with the acid, because it is pure gold.
Part 5 of 6: clean up the gold
Step 1. Add tap water to the mud remaining in the container
Mix the water and let the mud settle.
Step 2. Pour the water into the container you poured the acid into
Step 3. Rinse the gold slurry 3 or 4 times with water and get rid of the excess water
Step 4. Rinse the gold with ammonia
White vapors will emerge from the golden mud. Be sure to protect your eyes and avoid inhaling the fumes.
Step 5. Remove the ammonia
Use distilled water for this.
Step 6. Pour the mud into a large beaker
Get rid of all the distilled water so that only the mud is left.
Part 6 of 6: Replenish the gold
Step 1. Place the beaker on a baking sheet
Turn it on and allow the beaker to heat up gradually so that the thermal shock does not cause it to burst.
Step 2. Continue heating the mud until it has a powdery consistency
Step 3. Pour the mud over multiple layers of paper towels
Wrap the mud in the towels and soak the mud in alcohol.
Step 4. Put the slurry in a graphite crucible and melt it
The mud will take on a metallic appearance and will be 99% pure if done correctly.
Step 5. Pour the gold into an ingot mold
You can take it to a jeweler or a precious metals dealer to sell it if you wish.