How to Refine Gold Using Aqua Regia
Complete Step-by-Step Gold Recovery Guide
Refining gold with aqua regia is one of the most widely used chemical methods for dissolving and recovering gold from scrap jewelry, electronics, and other gold-bearing materials.
This guide explains the full refining workflow, from dissolution to recovered gold powder ready for melting.
This process is commonly used by small-scale refiners and laboratory refiners worldwide.
What Is Aqua Regia?
Aqua regia is a powerful acidic solution created by combining:
• Hydrochloric acid
• Nitric acid (or a nitric acid substitute)
When combined, these acids create a solution capable of dissolving gold, which most single acids cannot do alone.
During this process, gold is converted from solid metal into a dissolved gold chloride solution. The gold can then be recovered through chemical precipitation.
Materials Needed for Aqua Regia Gold Refining
To refine gold using aqua regia, you will typically need:
• Hydrochloric acid (31%)
• Nitric acid or nitric acid substitute
• Urea (to neutralize excess nitric acid)
• Sodium metabisulfite gold precipitant
• Stannous chloride test solution
• Borosilicate glass beaker
• Filtration setup (Buchner funnel and flask or gravity filtration)
• Heat source or hot plate
• Protective equipment and proper ventilation
If you are new to refining, a complete gold recovery kit simplifies this process by providing the core chemicals in one system.
Step 1: Prepare Your Gold Scrap
Before beginning:
• Remove plastic, rubber, stones, and non-metal components
• Cut large pieces into smaller sections
• Ensure scrap is clean and free of oils or debris
Clean, properly prepared scrap dissolves more efficiently.
Step 2: Dissolve Gold in Aqua Regia
Place gold scrap into a borosilicate glass beaker.
Add hydrochloric acid to cover the material.
Slowly add nitric acid or nitric substitute in small increments.
You will observe bubbling as base metals and gold begin reacting.
Continue adding nitric solution gradually until the gold is fully dissolved.
The solution will darken and may turn yellow to orange depending on concentration.
Do not add excessive nitric acid, as this can interfere with later precipitation.
Step 3: Filter the Gold Solution
Once dissolution is complete:
• Allow the solution to cool.
• Filter the solution to remove undissolved solids and impurities.
This produces a clean gold-bearing solution ready for testing and precipitation.
Step 4: Test for Dissolved Gold
Before precipitation, confirm that gold is present in solution using stannous chloride test solution.
Place a drop of solution on a testing surface and add one drop of stannous chloride.
A dark purple or black reaction indicates dissolved gold is present.
If no reaction appears, gold may already be fully precipitated or absent.
Step 5: Neutralize Excess Nitric Acid
Excess nitric acid can prevent gold from dropping out of solution.
To neutralize:
• Slowly add small amounts of urea to the filtered solution.
• Allow bubbling to subside before adding more.
Continue until nitric reaction is reduced.
Avoid adding excessive urea.
Step 6: Precipitate Gold from Solution
To recover gold:
Dissolve sodium metabisulfite in warm water.
Slowly add the solution to the filtered gold solution.
Stir gently.
Gold will begin to precipitate as a fine brown powder.
Allow the powder to fully settle, often several hours or overnight.
Step 7: Wash and Clean Gold Powder
Once precipitation is complete:
• Carefully decant remaining liquid.
• Wash gold powder with clean water multiple times.
• Optional: perform additional rinses to improve purity.
Proper washing improves final gold purity before melting.
Step 8: Dry and Melt Recovered Gold
Transfer the cleaned gold powder to a ceramic drying dish.
Allow it to dry completely before melting.
Melt using a crucible and appropriate flux such as borax to produce a solid gold button or bar.
Common Problems in Aqua Regia Gold Refining
Gold Will Not Precipitate
Likely cause: Excess nitric acid.
Solution: Neutralize further before adding precipitant.
Weak Stannous Test
Likely cause: Degraded stannous chloride.
Solution: Use fresh test solution.
Powder Disappears After Forming
Likely cause: Nitric acid still active and re-dissolving gold.
Solution: Ensure nitric is neutralized before precipitation.
Slow Filtration
Likely cause: Clogged filter paper.
Solution: Replace filter and pour slowly.
Safety Considerations
Aqua regia produces toxic fumes and should only be used with:
• Proper ventilation
• Acid-resistant gloves
• Eye protection
• Chemical-resistant containers
Never perform refining indoors without proper fume control.
Aqua Regia Refining Workflow Summary
Prepare Scrap
↓
Dissolve Gold
↓
Filter Solution
↓
Test for Gold
↓
Neutralize Nitric
↓
Precipitate Gold
↓
Wash & Dry
↓
Melt Recovered Gold
Final Thoughts
Aqua regia gold refining is a powerful and effective method for recovering gold from scrap materials when performed carefully and methodically.
Understanding each stage of the process ensures higher recovery rates and cleaner final metal.
For refiners who want a simplified setup, complete gold recovery kits provide the essential chemicals needed for each step of the process.
Recommended Gold Refining Supplies
If you're refining scrap gold, jewelry, or electronic components, using the correct chemicals and fresh reagents is critical for consistent results. These supplies are commonly used in the aqua regia gold refining process.
Gold Recovery & Refining Kit | Aqua Regia Gold Refining Chemical Kit – GOLD TESTING EQUIPMENT
Hydrochloric Acid for Aqua Regia