Refining Gold with Aqua Regia
Gold Flakes, Gold Sands, Gold Flake, Gold Sand,
In nature, gold is never found as pure 24 carrot gold. Gold is always combined with other  metals such as iron, silver, copper, platinum, etc....

All Natural Gold Nuggets and Gold Ores, have other elements and precious metals mixed with them. In order to separate these elements and get the gold into its pure form, a separation process or gold refining process needs to take place.   

There are many gold refining processes that have been used throughout the centuries. This article will focus on one particular wet chemical method of refining gold, or dissolving gold using hydrochloric acid and nitric acid to create an Aqua Regia gold solution.  

Aqua Regia Gold Solution

Aqua Regia, which is 3 parts hydrochloric acid and 1 part nitric acid, has the ability to dissolve gold, platinum, palladium, and other base and precious metals, and put them into a solution of Aqua Regia. Below is a simple explanation of how this happens.

A single atom of gold has 79 electrons.  Gold has one of its electrons orbiting way out in the outer most shell. This outermost electron can be easily captured, or shared with a different element under the right conditions.

A Chlorine atom has 7 electrons in its outer most shell but would like to have eight, so it takes one, or barrows one from gold. After doing so, the gold atom now has only 78 electrons and is no longer metallic gold but is a positively charged ion, or a cation. These gold cations are suspended in the Aqua Regia solution along with other precious metal cations of platinum, palladium, and base metals like copper, nickle, iron etc...

This gold solution, or Aqua Regia solution, now contains metal ions that have combined with the chlorine to form gold chloride, platinum chloride, etc...    The gold chloride and other metal chlorides in the Aqua Regia solution can now be separated from the undissolved material by filtering the Aqua Regia through a paper or glass filter. The material that was not dissolved by the Aqua Regia is filtered out leaving a clean, clear solution of Aqua Regia containing gold chloride and other metal ions in solution.

Now that the gold and other precious metals are in a clear, filtered, Aqua Regia solution, the dissolved gold and other metal chlorides can easily be separated from each other using a couple different gold refining methods.  Selective Precipitation, Solvent Extraction, and the use of Ion Exchange Resins are a few options available to selectively extract and separate gold from the other precious metals.  

For more information on refining gold, platinum, palladium, and other precious metals using an Aqua Regia solution, please read our other articles located on this website

Note: Gold refining using aqua regia can be dangerous or deadly if not done properly.  The gold chloride and other metal ions in Aqua Regia are toxic. The fumes generated by Aqua Regia in a gold refining process are also toxic. Use only professional Gold Refining Equipment and reliable safety equipment when dissolving gold and other metals in Aqua Regia.  Always use a fumed hood with an appropriate scrubber when refining gold or other precious metals.