copper cell after running

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123cp456

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Jul 10, 2018
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Hi All,

Newish to the forum, mainly reading in the background. I am currently running a copper cell on my very low gold grand ingots (mainly copper content) using the cell to get the copper off and processing the slimes for gold, i did a small test run which went perfectly, scaled up and ran longer (as was needed to get through the bar) but after a week the electrolyte started to get dark almost black and the copper deposits became thin, dark and a bit smelly. Im guessing it started to pull other pollutants like zinc and silver maybe.

My question i guess is...is that electrolyte now dead? is there a process for cleaning it back to its bright clear blue start point?

If not and the electrolyte has a 'shelf life' then what is the best and green/safe proper way to dispose of it, should mention its copper sulfate to clarify.
 

Martijn

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Welcome to the forum.
Are you using an anode bag to catch the slimes? Changing out the anode bag in time will extend the life of your electrolyte.

Other base metals will also use up free sulfuric acid forming sulfates so adding some sulfuric can help.

The electrolyte can be cleaned a bit. If it's contaminated too much you'll have to treat it as waste or find another use.
You can reclaim the copper by electrowinning or as copper sulfate crystals. By evaporating, cooling, crystallization, rinsing the crystals with cold water and filtering the electrolyte in between evaporation batches.
The rest is waste. If there is free acid left, you could use it to distill nitric from copper nitrate or convert copper chloride to copper sulfate.

Martijn.
 

123cp456

Member
Joined
Jul 10, 2018
Messages
9
Welcome to the forum.
Are you using an anode bag to catch the slimes? Changing out the anode bag in time will extend the life of your electrolyte.

Other base metals will also use up free sulfuric acid forming sulfates so adding some sulfuric can help.

The electrolyte can be cleaned a bit. If it's contaminated too much you'll have to treat it as waste or find another use.
You can reclaim the copper by electrowinning or as copper sulfate crystals. By evaporating, cooling, crystallization, rinsing the crystals with cold water and filtering the electrolyte in between evaporation batches.
The rest is waste. If there is free acid left, you could use it to distill nitric from copper nitrate or convert copper chloride to copper sulfate.

Martijn.
Hi Martijn

Im not using a back but plan to use a plastic catch bag on the next version on the cell, just to reduce filtering at the end and to keep any copper falling off the cathode completely separate.

In terms of treating it a waste, are we talking about steel bar to drop any metals then neutralise for disposal?
 

123cp456

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Just some follow up context for anyone interested and or with some ideas on a better method.
I am processing low grade gold 5% per weight and my material is mainly copper but also silver, nickle, tin, lead and zinc...that i know of.
The idea behind the cell is to take care of as much copper as possible, in order to save chemicals further down the line. Ive seen someone mention they wash slimes in HCL to remove extra base metals, zinc, nickle lead etc then nitric wash to get the silver and any remaining copper, then AR before dropping.
I have had success with this process so far, i just note that i seem to be getting through electrolyte quickly, my last run after 4 days of running i removed a solid lump of copper that had plated onto the wire, which was exactly as i wanted, i used a fresh wire for the next couple of days and after the new wire went in, all the copper that plated onto the wire fell off at the slightest movement (so ended up in my slimes, defeating the point, but will have a separation tank on cell 2.0)
 

nickvc

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You are encountering the one problem with running cells and that is fouling of your electrolyte because of the mix of metals in your feed stock , what is happening is that the copper level in your electrolyte is falling too low , try adding copper sulphate crystals to boost the copper levels as the cell runs but I think you need to do this daily at least , it might work but can’t confirm it so experiment and report your findings .
 

123cp456

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Jul 10, 2018
Messages
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You are encountering the one problem with running cells and that is fouling of your electrolyte because of the mix of metals in your feed stock , what is happening is that the copper level in your electrolyte is falling too low , try adding copper sulphate crystals to boost the copper levels as the cell runs but I think you need to do this daily at least , it might work but can’t confirm it so experiment and report your findings .
Thanks for the feedback, I had my suspicions that this is what was happening and was going to try adding more in the first place and if i saw it getting dirty i will add more copper sulfate to try balance the electrolyte.

I know this is not the best way to process the material i have, BUT its pretty hands of, pretty 'safe' and pretty cheap, so i will bare with it for now.

Was also thinking i have too much feed stock, i started with 750g in 4L, got it down to approx 550g before i started fouling my solution. Perhaps i also need a much bigger tank 10/20L maybe?
 

Martijn

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Dont scale-up until you have a system that works. Small batches, small mess to clean up if something goes wrong.
Using an anode bag will greatly improve on the lifespan of your electrolyte.
 

nickvc

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Dont scale-up until you have a system that works. Small batches, small mess to clean up if something goes wrong.
Using an anode bag will greatly improve on the lifespan of your electrolyte.
I have to agree an anode bag will help and again test with small set ups as martyin suggests.
 

123cp456

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Further update - I am now using a separate plastic tank inside my main tank to separate the slimes from any copper debris, with small dacron filter to further reduce cross contamination. The solution is running absolutely fine and getting through the bar at a good rate. In addition to the filter i have reduced the amount of sulfuric and increased the copper sulfate which i think is working well for me. Yes the copper is not plating to a solid lump on the cathode, however i dont mind this, as i just want the copper away from my PM in order to drastically reduce the amount of chemical needed to further process/refine. I assume (wont know until clean out) that the copper falling to the bottom, in its own tank, will be collectable? dried and melted i guess.

Thanks all for advice and feedback, once ive cleaned out in a few days i will take some pictures to maybe explain better if anyone is interested
 

Martijn

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The gold and possibly other precious metals will be in powder form in the sulfate slimes. Easy to process or leach the contamination out.
Melting that into a dirty button will only complicate further refining.
Roasting the slimes and leaching with HCl before AR is what did.
Some go straight for AR.
 

123cp456

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Jul 10, 2018
Messages
9
The gold and possibly other precious metals will be in powder form in the sulfate slimes. Easy to process or leach the contamination out.
Melting that into a dirty button will only complicate further refining.
Roasting the slimes and leaching with HCl before AR is what did.
Some go straight for AR.
Yes sorry my last ramble wasn't clear. I've affectivity got two tanks connected. One to capture precious metals and one just to collect any dropped copper. The PM slimes I bang in AR and double refine, had good results on that so far, the other tank will have just copper so it's this that I was talking about melting down on its own.
 
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