How to Refining Gold (with Pictures)

2024 Author: Jason Gerald | [email protected]. Last modified: 2024-01-19 22:11

You may be interested in earning some extra money refining gold at home, or it could be that you as a jeweler want to refine gold independently. There are many ways to refine gold on a small scale as long as we heed safety precautions. This article will teach you how to purify gold using the "aqua regia" method.

Step

Part 1 of 6: Melting Gold

Step 1. Place gold jewelry, gold powder, or gold nuggets in a bowl/melting cup

Most crucibles are made of graphite, which is resistant to the melting process of the material inside.

Step 2. Place the cup on a fireproof surface

Step 3. Point the acetylene torch at the gold

Point the flame at the gold until the gold is completely melted.

Step 4. Lift the cup using the cup tongs

Step 5. Separate the gold into small chunks and let it harden

This is known as the "making shot" process. If what is being refined is a small piece of jewelery such as a ring, you just need to melt the jewelery without making the beads.

Part 2 of 6: Add Acid

Step 1. Select the appropriate container

• For every 31.10 grams of gold you want to refine, you need a container with a capacity of 300 milliliters.
• Use a thick plastic case or "Pyrex Vision Ware" container.

Step 2. Wear personal protective equipment

• Use rubber gloves to protect your hands from acid. Always wear these gloves when working with any of the chemicals mentioned in this article.
• Wear a rubber apron to protect your clothes.
• Use protective eyewear to protect the eyes.
• Consider wearing a gas mask to avoid inhaling toxic fumes.

Step 3. Place the container in a well-ventilated area

The acid reaction in the aqua regia process produces a sharp and toxic gas vapor.

Step 4. Pour 30 milliliters of nitric acid for every 31.10 grams of gold in the container

Let the acid react for 30 minutes.

Step 5. Add 120 milliliters of hydrochloric acid for every 31.10 grams of gold in the container

Leave the solution overnight and all vapors from the acid are released.

Step 6. Pour the acid solution into another large container

• Make sure the impurities from the acid don't come out to avoid contaminating the gold.
• The acid solution to be used should be a clear emerald green color. If still cloudy filter with a Buchner funnel.

Part 3 of 6: Add Urea and Gold Precipitant Solution

Step 1. Heat 0.946 liters of water then add 0.458 kg urea to it

Heat until boiling.

Step 2. Slowly add the water/urea solution to the acid solution

• This acid solution will produce a lot of air bubbles when you add the water and urea solution. Add the mixture slowly so that the acidic liquid doesn't overflow out of the container.
• The water/urea solution will neutralize the nitric acid but not the hydrochloric acid in your solution.

Step 3. Add a gold-selective precipitating solution to 0.946 liters of boiling water according to the manufacturer's instructions

• As a general rule, you will need 28.349 grams of precipitate for every 31.10 grams of refined gold.
• Do not bring your face close to the container. The smell of the solution is very strong and pungent.

Step 4. Add the aqueous/precipitating solution carefully to the acid solution

• The acid solution will turn a cloudy brown, due to the gold particles separating.
• Wait 30 minutes for the precipitating solution to act on the gold particles.

Part 4 of 6: Testing Dissolved Gold in Acid

Step 1. Dip the stirring rod in the acid solution

Step 2. Drop one drop of the solution on the end of the tissue

Step 3. Add one drop of the precious metal test solution to the drops of acid

If the drop turns purplish, allow the precipitating solution to work again before removing the acid solution.

Step 4. Pour the acid into a new clean container as soon as the acid solution is free of gold particles

• What is seen is a yellow-brown acid solution with a silt-like precipitate accumulating at the bottom of the container.
• Do not throw the mud because it is pure gold deposit.

Part 5 of 6: Cleaning Gold

Step 1. Add tap water to the mud in the container

Stir gently then let the mud settle.

Step 2. Pour the water into the container of the former acid solution

Step 3. Rinse the gold 3 or 4 more times with tap water and then collect the remaining rinse water

Step 4. Rinse the gold precipitate with ammonium hydroxide

You will observe cloudy white steam liberated from the golden mud. Be sure to wear goggles and a face mask for safety so as not to be exposed to or inhale the fumes that arise.

Step 5. Rinse off the ammonia solution adhering to the mud with distilled water

Step 6. Pour the mud into a large beaker

Discard all the distilled water until only mud remains.

Part 6 of 6: Collecting Gold Back

Step 1. Place the beaker on the electric heater

Turn on the heater and heat the beaker slowly so that the heat wave doesn't cause the glass to crack or break.

Step 2. Heat until the mud turns into a fine powder

Step 3. Pour the mud on sheets of tissue paper

Wrap the mud carefully and then soak it in alcohol.

Step 4. Put the mud in the graphite crucible to melt

When properly processed, the sludge will turn into metal with a purity of 99%.

Step 5. Transfer the gold into the ingot mold

If you want, take it to a jeweler or precious metal dealer to exchange for cash.

Tips

Refining gold independently before it is offered or sold can save you a lot of money