Gold Stripping Agent Test: Eco-goldex E series

Gold stripping agent test: Eco-goldex E series.


Let me first declare that it is a test done by myself and I was not paid a single penny by anyone to use Eco-goldex E-series gold stripping agent. The opposite, I spent 92,50 EURO to buy 1 kilogram of Eco-goldex E series and have it shipped to Europe.

Here is the process I followed in my first test:

Step 1: Dissolved 5 grams of Eco-goldex E series in 100 ml water. 50 degrees Celsius. Stirring - ON. Used magnet to remove any magnetic particles from the solution.
Step 2: Used stripping agent to strip gold from at about 300 grams of computer gold platted pins - different quality of the pins. Heating - ON, 50 degrees Celsius. pH = 13-14. Manual stirring. Took 5-10 min to strip gold from each 50 grams pins batch.
Step 3: Used hydrochloric acid (muriatic acid, HCl) to adjust pH to at about 6.5-7.0. Heat - OFF. Manual stirring. Done in a hood as solution contains cyanide!!! EXTREMELY DANGEROUS!!!!! You can also precipitate gold from all alone solution and skip this step! Better don’t do it!!!
Step 4: Filtered solution. Rinsed filter multiple times with distilled water.
Step 5: Used Zinc (Zn) powder to reduce Au(3+) to colloidal gold Au(0). Using Zinc powder can be dangerous especially in the case when solution is acidic as hydrogen gas is generated and it can cause fire or explosion!
Step 6: Solution was filtered and filter rinsed with distilled water. Stannous chloride test used to check if there is any gold left in the solution - NEGATIVE.
Step 7: Filter was put in a beaker and Hydrochloric acid added. First to remove any Zinc left from Gold reduction and second to be used for gold dissolving with Aqua Regia. 70 ml 34% HCl added total. HCl is highly corrosive and skin irritant. Fumes are toxic!
Step 8: Concentrated Nitrogen Acid slowly added to the 70 ml HCl and filter from step 6. Aqua Regia formed to dissolve filter and gold. Heat - ON at 100 degrees Celsius. Fumes are toxic during this reaction!
Step 9: Urea added to remove any excess of Nitrogen Acid.
Step 10: Solution filtered and filter rinsed with distilled water.
Step 11: Sodium Metabisulfite added to reduce gold from Au(3+) to colloid Au(0).
Step 12: Gold residue decanted and washed multiple times with distilled water. Finally boiled in distilled water.
Step 13: Gold powder melted. Result is 0.46 grams of high purity gold.

I will definitely continue using this reagent in my workshop! Thank you John for the permission to publish videos with your company products and for the great gold stripping agent!