Knowing how to refine gold can come in handy if you want to earn a little more from its sale or if you are a jeweler who wants to learn the procedure to be able to implement it at home. Provided that the necessary precautions are taken, there are many methods for refining gold in small quantities.
Steps
Method 1 of 6: Fund the Gold
Step 1. Put your jewel or gold nugget inside a crucible
Most crucibles are made of graphite, which allows the vessel to withstand the highest temperatures.
Step 2. Place the crucible on a fireproof surface
Step 3. Melt the gold with an acetylene torch
Keep the flame of the torch on the gold until it melts completely.
Step 4. Take the crucible with the special tongs
Step 5. Divide the gold into smaller parts and let them solidify
If you are refining small jewelry, such as a ring, you can simply melt the gold without breaking it up.
Method 2 of 6: Add the acid
Step 1. Get the right container
- As for the size of the vessel, you will need 300ml of capacity for every 31.10g of gold to refine.
- Use very thick plastic buckets or borosilicate glass containers.
Step 2. Put on the protective equipment
- Wear rubber gloves to protect your hands. Wear gloves whenever you handle the chemicals mentioned in this article.
- Wear a rubber apron to protect your clothes.
- Wear eye protection goggles.
- Also wear a face mask to protect yourself from toxic fumes.
Step 3. Put the container outside in a well-ventilated area
Reactions between acids in the aqua regia process produce extremely dangerous toxic fumes.
Step 4. Pour 30 ml of nitric acid for every 31.10 g of gold into the container
Let the acid react with the gold for 30 minutes.
Step 5. Add 120 ml of hydrochloric or muriatic acid for every 31.10 g of gold in the container
Let the solution sit overnight for the fumes to disperse.
Step 6. Pour the acid into another container
- Make sure that no mineral fragments are transferred together with the acid, as it could contaminate the gold.
- The acid should have assumed an emerald green color. If it takes on a cloudy color, clean it with a Büchner filter.
Method 3 of 6: Add the Urea and the Precipitant
Step 1. Heat 1 liter of water with the addition of 450 g of urea
Bring the solution to a boil.
Step 2. Gradually add the water / urea mixture to the acid
- The acid will begin to boil. Add the water / urea mixture slowly, so that the acid does not overflow from the container.
- The water / urea mixture neutralizes nitric acid but not hydrochloric acid.
Step 3. Add a precipitating agent for gold in 1 liter of boiling water, following the directions for using the product
- In general, you should add 31.10 g of precipitant for every 31.10 g of gold.
- Avoid putting your face close to the container; the smell of the solution is very pungent.
Step 4. Slowly add the water / precipitant solution to the acid
- The acid will take on a cloudy brown hue, caused by the separation of the gold particles.
- Wait 30 minutes for the precipitating solution to take effect.
Method 4 of 6: Analyze the Acid for Gold
Step 1. Dip a loop in the acid solution
Step 2. Pour a drop of solution onto a paper towel
Step 3. Pour a drop of liquid reagent for the detection of precious metals on the acid stain
If the latter becomes purple, it means that you will have to leave the precipitant to act for some time.
Step 4. Once separated from the gold particles, pour the acid into a clean container
- The acid should have taken on an amber hue and a sort of sludge should be visible on the bottom of the container.
- Do not discard this slime substance along with the acid. This is pure gold!
Method 5 of 6: Clean the Gold
Step 1. Pour tap water into the container
Stir and wait for the gold to settle back to the bottom.
Step 2. Pour the water into the container where you poured the acid
Step 3. Rinse the gold another three or four times discarding the excess water
Step 4. Rinse the gold with ammonia
You will see white vapors exhale from the gold. Be sure to wear goggles and avoid inhaling these fumes.
Step 5. Rinse the gold with distilled water
Step 6. Pour the gold into a fairly large beaker
Eliminate the distilled water so that only the gold remains.
Method 6 of 6: Restore the Gold
Step 1. Place the beaker on a heating pad
Turn on the griddle and allow the beaker to heat up slowly to prevent it from shattering.
Step 2. Continue to heat the gold until it takes on a consistency similar to that of the powder
Step 3. Pour the gold on paper napkins arranged in layers
Wrap the gold in handkerchiefs and dip it in alcohol.
Step 4. Put the gold in a graphite crucible and melt it
The compound will take on a completely different aspect, becoming 99% pure gold if you have followed the procedure correctly.
Step 5. Pour the gold into an ingot mold
You can now go to a jeweler to sell your gold if you wish.
