Reverse electroplating gold of copper base

shop deals on amazon
xelexo
Shop deals on ebay
Advertise with us
Gold Refining Forum

Help Support Gold Refining Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
P

Prospectorbob

Member
Joined
Jun 11, 2022
Messages
14
Location
Lismore
Copper items dipped in 24k gold. I am getting set up to reverse electroplate them in sulphuric acid, will my 12v 4amp battery charger do the job, or should I have a controller for the current. Waiting for parts for the fume hood, so I have time to get other things right. I did think of just going straight to AR but the gold is testing as 24K on these first items. All advice appreciated
 
Prospectorbob said:
Copper items dipped in 24k gold. I am getting set up to reverse electroplate them in sulphuric acid, will my 12v 4amp battery charger do the job, or should I have a controller for the current. Waiting for parts for the fume hood, so I have time to get other things right. I did think of just going straight to AR but the gold is testing as 24K on these first items. All advice appreciated
Click to expand...
In order to get purer gold you have to optimize voltage according to bath resistance


Prospectorbob said:
Copper items dipped in 24k gold. I am getting set up to reverse electroplate them in sulphuric acid, will my 12v 4amp battery charger do the job, or should I have a controller for the current. Waiting for parts for the fume hood, so I have time to get other things right. I did think of just going straight to AR but the gold is testing as 24K on these first items. All advice appreciated
Click to expand...
 
Last edited:
Sulfuric acid is a very bad conductor. As long as there is gold on the copper to be stripped and there is good contact between the pins there will be a current.
Depending on the size of your cathode and anode basket, I think 12 V will do just fine. Check the temerature often with a simple laser thermometer. Keep it below 50 degrees C.
Have an ampmeter in series to see when the current drops to zero. That's when all gold is stripped. Don't bother chasing the tiny spots leftover on the copper, it is much less than you think.
My stripping video is in this post:
https://goldrefiningforum.com/threads/sulfuric-stripping-gold-plating-video.30560/Martijn.
 
I think the meaning of Ki that Lino posted means potassium iodide. It is used to strip gold plate as well and does not use sulfuric acid.
 
Martijn said:
Sulfuric acid is a very bad conductor. As long as there is gold on the copper to be stripped and there is good contact between the pins there will be a current.
Depending on the size of your cathode and anode basket, I think 12 V will do just fine. Check the temerature often with a simple laser thermometer. Keep it below 50 degrees C.
Have an ampmeter in series to see when the current drops to zero. That's when all gold is stripped. Don't bother chasing the tiny spots leftover on the copper, it is much less than you think.
My stripping video is in this post:
https://goldrefiningforum.com/threads/sulfuric-stripping-gold-plating-video.30560/Martijn.
Click to expand...
Thanks Martin, I will put up my results when done.
 
Normally a 12V battery charger is too many volts and not enough control for decent plating work, where a lab power supply is preferred. But "reverse electroplating" is just electrically carpet bombing all the base metals off the anode, freeing the gold, so a battery charger should work fine.

Be ready for the charger to overheat, I've had them catch fire on a short. The anode bubbles can also throw up a fine acid mist laden with heavy metal ions, so I'd use a good fume hood setup, or a secondary container.
 
Not trying to nit pick but technically, there is no such thing as reverse electroplating. It is stripping. An electrolytic stripping cell. A voltage regulator is very easy. You can actually run the current through a trim pot or low current potentiometer. A trim pot will need to be adjusted with a tool, like a screw driver, where a potentiometer will normally have some sort of knob depending on the current load. You can buy both amp meter and volt meter on ebay for a few dollars. A power supply out of any desktop PC has 3v, 5v and 12v output. Put a 10 ohm resistor on any yellow wire and black wire to simulate a load so the switching power supply stays "on". I use them as I need them. Anyone that scraps PC's should have a few just laying around handy.
 
Geo said:
Not trying to nit pick but technically, there is no such thing as reverse electroplating. It is stripping. An electrolytic stripping cell. A voltage regulator is very easy. You can actually run the current through a trim pot or low current potentiometer. A trim pot will need to be adjusted with a tool, like a screw driver, where a potentiometer will normally have some sort of knob depending on the current load. You can buy both amp meter and volt meter on ebay for a few dollars. A power supply out of any desktop PC has 3v, 5v and 12v output. Put a 10 ohm resistor on any yellow wire and black wire to simulate a load so the switching power supply stays "on". I use them as I need them. Anyone that scraps PC's should have a few just laying around handy.
Click to expand...
Hi Geo, thanks for your input. My understanding of ‘stripping‘ in the electrolysis of metals industry is the process of removing the refined metal from a Cathode, usually in a sheet form. I suppose reverse electroplating might not be the right term but I’m not sure ‘stripping‘ fits the description either. I have googled it and some answers are definitely not correct but that’s all ok and I mean no offence in this reply to you. I have purchased a DC- DC adjustable step-down module amd installed it on the output side of the 12v 4amp old style battery charger, then run the positive lead through a digital metre and connected it to a 6v torch globe. Switched it on and adjusted the volts on the step down to 3v, and whammy, all good to go. I won’t know what the amps will be until I connect up in the cell. The battery charge have overload protection so I’m not sure yet whether I need anything else in the lines. I guess I’ll know soon. Cheers
 
Stripping is a relative term. It can describe several actions. Physical, chemical, electro-chemical. It usually has another descriptor to narrow down the true meaning. Electronic stripping cell is an electro-chemical term. It involves using an electrolytic stripping where a current is applied to the work piece or anode. The current passes through the electrolyte completing the circuit. Since the electrolyte is sulfuric acid, The electrons leaving the anode generates oxygen at the anode with the current forcing the splitting of water molecules with the oxygen combining with the sulfuric acid creating a very small amount of persulfuric acid on the surface of the anode. Gold is dissolved by this minute amount of persulfuric acid and is carried away from the anode with the electron flow. This species of persulfuric acid is short lived and decomposes about as fast as it is generated. Sulfuric acid can not hold gold in a liquid form and so as the persulfuric acid decomposes, the gold falls out of solution as fine metallic particles. In this way, the gold is stripped from the work piece on the side facing the cathode and deposited as a black metal powder on the bottom of the cell. The electrolyte has to be concentrated sulfuric acid.
 
Geo said:
Stripping is a relative term. It can describe several actions. Physical, chemical, electro-chemical. It usually has another descriptor to narrow down the true meaning. Electronic stripping cell is an electro-chemical term. It involves using an electrolytic stripping where a current is applied to the work piece or anode. The current passes through the electrolyte completing the circuit. Since the electrolyte is sulfuric acid, The electrons leaving the anode generates oxygen at the anode with the current forcing the splitting of water molecules with the oxygen combining with the sulfuric acid creating a very small amount of persulfuric acid on the surface of the anode. Gold is dissolved by this minute amount of persulfuric acid and is carried away from the anode with the electron flow. This species of persulfuric acid is short lived and decomposes about as fast as it is generated. Sulfuric acid can not hold gold in a liquid form and so as the persulfuric acid decomposes, the gold falls out of solution as fine metallic particles. In this way, the gold is stripped from the work piece on the side facing the cathode and deposited as a black metal powder on the bottom of the cell. The electrolyte has to be concentrated sulfuric acid.
Click to expand...
Thanks again Geo, that makes complete sense and adds to my education.I really appreciate the time you have put into answering. This is a great forum and I am sure I will be able to fine tune my metallurgy journey with this type of help. Again, Thank you. Regards, Bob
 
So curious what would happen if sulfuric was replaced with salt water?
Geo said:
Stripping is a relative term. It can describe several actions. Physical, chemical, electro-chemical. It usually has another descriptor to narrow down the true meaning. Electronic stripping cell is an electro-chemical term. It involves using an electrolytic stripping where a current is applied to the work piece or anode. The current passes through the electrolyte completing the circuit. Since the electrolyte is sulfuric acid, The electrons leaving the anode generates oxygen at the anode with the current forcing the splitting of water molecules with the oxygen combining with the sulfuric acid creating a very small amount of persulfuric acid on the surface of the anode. Gold is dissolved by this minute amount of persulfuric acid and is carried away from the anode with the electron flow. This species of persulfuric acid is short lived and decomposes about as fast as it is generated. Sulfuric acid can not hold gold in a liquid form and so as the persulfuric acid decomposes, the gold falls out of solution as fine metallic particles. In this way, the gold is stripped from the work piece on the side facing the cathode and deposited as a black metal powder on the bottom of the cell. The electrolyte has to be concentrated sulfuric acid.
Click to expand...
As
 
It would form chlorine gas in solution and start dissolving base metal. After the chlorine is liberated, it will start forming hydroxide next.
 
So curious what would happen if sulfuric was replaced with salt water?
Geo said:
Stripping is a relative term. It can describe several actions. Physical, chemical, electro-chemical. It usually has another descriptor to narrow down the true meaning. Electronic stripping cell is an electro-chemical term. It involves using an electrolytic stripping where a current is applied to the work piece or anode. The current passes through the electrolyte completing the circuit. Since the electrolyte is sulfuric acid, The electrons leaving the anode generates oxygen at the anode with the current forcing the splitting of water molecules with the oxygen combining with the sulfuric acid creating a very small amount of persulfuric acid on the surface of the anode. Gold is dissolved by this minute amount of persulfuric acid and is carried away from the anode with the electron flow. This species of persulfuric acid is short lived and decomposes about as fast as it is generated. Sulfuric acid can not hold gold in a liquid form and so as the persulfuric acid decomposes, the gold falls out of solution as fine metallic particles. In this way, the gold is stripped from the work piece on the side facing the cathode and deposited as a black metal powder on the bottom of the cell. The electrolyte has to be concentrated sulfuric acid.
Click to expand...
As
Geo said:
It would form chlorine gas in solution and start dissolving base metal. After the chlorine is liberated, it will start forming hydroxide next.
Click to expand...
So capturing gold through electrolyte solution of salt water is possible but leaves you with base metals to separate mixed with your gold, correct?
Geo said:
It would form chlorine gas in solution and start dissolving base metal. After the chlorine is liberated, it will start forming hydroxide next.
Click to expand...
 

Latest posts

Back
Top