Electrochemistry What is the best cathode for Gold electrolysis refining

[tvanasetta]

I normally work on jewelry scrap with Aqua regia process and use sodium metabisulphate method to collect gold. I'm thinking about building electrolysis system. What cathode should I use for (+) and (-) side. Read from many source they use gold plate and gold foil. Or is it should be other metal. Is this process faster than sodium metabi method?

my current process is;
1. put scrap in AR (1:2) and heat it 65 C and stir until no reaction
2. Filter AgCl out
3. put in sodium Meta. to collect gold.
4. wash it with water and collect gold sand on filter paper.

If i could get electrolysis system in place I will replace sodium meta usage. Am I in correct way? Frankly, I have no information about electrolysis system and no experience too. Could any on give me some advise? Is it good to change? Normally I work with output gold between 200 - 500 gram.

 

[nickvc]

Look up the Wohlwill cell.
The electrolytic processing of metals always needs high grade feed stock 95%+ for good quality metals as the end result so you need to refine your scraps and cast an anode which will require bagging, you will need fine gold to create your electrolyte and also for making your cathode.
The problem with cell refining is it ties up quantities of metals continuously but it can and does produce high quality metals.

 

[tvanasetta]

Are there anyway around it? Can I stick 12V high amp to my AR to make it work?

 

[nickvc]

If your looking to achieve fine gold then sorry no there's no way round it, you can use cells such as the sulphuric cell to recover but it's not a refining process the recovered material will still need refining.

 

[ΩPhoenix]

If your looking to achieve fine gold then sorry no there's no way round it, you can use cells such as the sulphuric cell to recover but it's not a refining process the recovered material will still need refining.

If you are looking to produce 9999 fine gold you need to make your cathode from 9999 gold. The refinery that I worked in recycled a portion of their 9999 finnished
product to remelt and roll down to 1/4" thick rectangular cathodes. The rectifier was a pulsating current specifically designed for the Wohlwill process. The on an off again current allows the silver chloride and other impurities to fall off the cathode and not become trapped in the crystalline deposits.
If you are planning to sell at spot to gold buyers there is no need to produce a higher purity than 99.9%. I would just stick with sodium sulfite, ferrous sulfate or sodium meta bisulfite. I'ts important to produce 9999 and 99999 for certain medical computer/electronic or research applications that you sell at a premium price.

 

[Westerngs]

tvanasetta,

For the amount for gold you are refining, I would stick with the method you are currently using. If done carefully, you should always get 4 9's gold.

The electrolytic refining method ties up a lot of gold in the electrolyte and the anode.

 

[goldsilverpro]

I know of no electrolytic cell that can dissolve karat gold efficiently. The Wohlwill cell would be used to raise the purity of gold that's already been purified by aqua regia (or, whatever). An electrolytic cell won't replace AR.