How to refine gold (with pictures)

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).

Steps

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.