Electrochemistry au,ag,cu,mixture how to recover thru electrolysis

[jar50s]

hi i am a new member i was learning how to recover metals with an old friend but i lost contact with him so i am stuck please help.

i learned to recover thru the acid way ag and au but some guy i met told me that to get the precipitate and just melt it down and that thru electrolysis i can recover faster and at less expense can you guys help me out ??? sad to say but that guy was teaching me but he is really far away and have no way to reach him. but i always asked my self in the first place is it possible??? and how to do it if it is possible??

well it has various metals pb au ag cu etc... but i only want to recover cu ag au please help this all i think about sense my friend told me

 

[nickvc]

Welcome to the forum.
First the bad news, electrolytic refining is only possible with high grade material, the starting metal needs to be at least 95% pure if you wish to extract pure metal at the end the balance of materials will report as slimes in your anode bag. If your starting alloy is a mix of many metals of low % then acid refining is the only way forward.
Reading your post I guess that you may well be recovering materials from e scrap, if that is the case we have methods to remove many of the troublesome metals before attempting to refine the values.
Start your research by taking the guided tour and try and read C.M.Hoke which is available free as a download off many members signature lines, visit our very own Lazersteves site where there's videos to watch and purchase. Unfortunately there is no magic simple way to seperate metals but many of the easiest and cheapest ways are explained in depth here on the forum you just need to do your research.

 

[jar50s]

it has a lot of cu and a lot of ag and alittle bit of au and pb that's about it but due to the high cu level it makes it even harder to recover the silver thru acid any tip??? and i will do some research

and i also have minerals with only ag au no cu or contaminants but in dirt form and i bought this materials to learn a bit because the company i work for sells and buy minerals but i noticed that there's a lot of people who use the copper way of getting silver cement and just dump it so if i could recover the cu.

and i have access to all different types of chemicals . and i really appropriate the help and sorry i just dont know the correct question to ask lol

 

[butcher]

jar50s,

Nickvc gave you the best advice around to follow, every material or situation can be different and present its own set of problems, there is a tremendous amount of knowledge and understanding you will need to recover and refine, this knowledge cannot be gained by jumping in and dissolving metals with acids and then asking questions why it did not work like the few pages you have read said it does.

By following the advice Nickvc offered, you can gain that knowledge, it will take a lot of hard work studying the materials provided, Hoke's book is an excellent source of information, understanding the principles the book is based on, can help you to deal with most any material, and be able to recover or refine, the forum also takes up with many of the types of material that Hoke's book does not go into depth about, her book will prepare you to understand the recovery and refining process, the forum will help with some details and different processes, if you think you do not understand all of your questions now, just wait until you begin to study, the more you learn the more questions you will see you need to study to learn, this learning is not hard, and can be fun, but it does take a lot of time and dedication and hard work, so get Hokes and begin your wonderful journey into the field of recovery and refining of precious metals.

 

[vinod patel]

hi my friend jar50s, vinod here, dont warry ,you said you have job in company as a salesman ,and you bye and sale a mineral dirt contain gold ,silver,copper,and lead- if you want to electrolyte prociger use for dirt it is not possible- for it must be it convert to metal bar, and then copper sulphate concentrted solution in distiled water, used for it with 5%of sulfuric acid slowlly added in it, this is electrolyte solution is done. now take your own above sayed metal bar as an anode and kethod is a pure copper plate put in it and apply it to 2 to 3volt 6amp. dc current- so it work as copper refining and undissolved silver and gold particals set to the bottem of the anode as anode mude. but it must be importent to seprate this mude with mude bages. now you have only 2 problem 1st how to melting dirt to convert it in to metal form ? and 2nd is how to seprate tht anode mude? also every time scrpe of the fine copper from kethode plate. your friend , vinod patel.

 

[butcher]

vinod patel,
I believe the bar would have to be a high purity copper anode (with only trace's of values), for that procedure to work very well. Then you would be in the copper refining business not the gold recovery business.

 

[ElectricAngel]

vinod patel,
I believe the bar would have to be a high purity copper anode (with only trace's of values), for that procedure to work very well. Then you would be in the copper refining business not the gold recovery business.

I am intrigued by the possibility in this post. What is the minimum purity of copper anode one must have to successfully refine copper? My thought is this: suppose I want to make pure silver from coins that are 40% silver. Assume a 20 gram coin with 8 grams of silver, 12 of copper. Now, I melt the coin with 60 grams of pure copper to get a bar that is 90% copper, and 10% silver. If I electrorefine this copper-silver bar, what happens?

Does the copper go to the cathode and the silver drop out in the anode slime? Then I could capture the anode slime, which theoretically should be nearly-pure silver, and use the refined copper for the next-go-round of the process.

This allows me to refine silver from copper-silver alloys without needing nitric or silver nitrate, only sulfuric acid and copper sulfate. I know it is possible to electrorefine sterling silver at 92.5%, and have heard that US coin silver at 90% also works OK, so does the same hold true for electrorefining copper?

 

[nickvc]

Welcome to the forum.
I can see how your mind is working here but unfortunately the slimes produced by refining the copper will not be fine silver but have copper and any other contaminants in. To achieve fine silver you would then need to build a silver cell. The truth is you have a known quality and readily accepted form of silver in your coins so why bother to produce an unknown product with no guarantee of purity.

 

[NobleMetalWorks]

vinod patel,
I believe the bar would have to be a high purity copper anode (with only trace's of values), for that procedure to work very well. Then you would be in the copper refining business not the gold recovery business.

I am intrigued by the possibility in this post. What is the minimum purity of copper anode one must have to successfully refine copper? My thought is this: suppose I want to make pure silver from coins that are 40% silver. Assume a 20 gram coin with 8 grams of silver, 12 of copper. Now, I melt the coin with 60 grams of pure copper to get a bar that is 90% copper, and 10% silver. If I electrorefine this copper-silver bar, what happens?

Does the copper go to the cathode and the silver drop out in the anode slime? Then I could capture the anode slime, which theoretically should be nearly-pure silver, and use the refined copper for the next-go-round of the process.

This allows me to refine silver from copper-silver alloys without needing nitric or silver nitrate, only sulfuric acid and copper sulfate. I know it is possible to electrorefine sterling silver at 92.5%, and have heard that US coin silver at 90% also works OK, so does the same hold true for electrorefining copper?

It depends what type of cell you are using and what material there is the majority of, what the cathode/anode are made out of, what your amps/volts are, etc etc etc.

The material doesn't have to be 95% of one type of metal for it to work, but it should be 95%+ if you expect to get industry standard on the cathode.

I recently ran a copper cell with material that was much lower than 95% copper and the rest silver. Some silver goes into solution but is displaced later by copper going into solution. So I can run copper/silver material so long as I run pure copper after to displace the silver out of solution. Neither the silver nor copper are pure, there are always contaminants. However once it's separated to that point it usually only takes melting into anode bars and one more refining to get it to industry standard. You can always test the solution for silver by taking a small amount and adding a little HCl to see if it makes a cloud of AgCl.

There are so many different ways to use cells, so many different ways to upgrade material or refine in a dirty cell, then high purity cell. Different ways to use amps and volts, different solutions, on and on and on. But if you are refining something other than gold, specially material with large amounts of silver, cells are the way to go.

I'm actually looking for a good book on electrolytic refining with examples and the math to figure out the proper build specs to make your own cells. If anyone can suggest a book that covers eletrorefining precious metals I would be grateful.

Scott

 

[nickvc]

Scott I believe our very own goldsilverpro has a book on silver recovery and refining available from lazersteves site and he has written extensively on the subject here on the forum even posting designs of some of his simplest and best cells.

 

[ElectricAngel]

The material doesn't have to be 95% of one type of metal for it to work, but it should be 95%+ if you expect to get industry standard on the cathode.

I recently ran a copper cell with material that was much lower than 95% copper and the rest silver. Some silver goes into solution but is displaced later by copper going into solution. So I can run copper/silver material so long as I run pure copper after to displace the silver out of solution. Neither the silver nor copper are pure, there are always contaminants. However once it's separated to that point it usually only takes melting into anode bars and one more refining to get it to industry standard. You can always test the solution for silver by taking a small amount and adding a little HCl to see if it makes a cloud of AgCl.

There are so many different ways to use cells, so many different ways to upgrade material or refine in a dirty cell, then high purity cell. Different ways to use amps and volts, different solutions, on and on and on. But if you are refining something other than gold, specially material with large amounts of silver, cells are the way to go.

I'm actually looking for a good book on electrolytic refining with examples and the math to figure out the proper build specs to make your own cells. If anyone can suggest a book that covers eletrorefining precious metals I would be grateful.

Scott

Thanks, Scott. I had tried Canadian 1968 Quarters (50/50 Cu/Ag) in an electrorefining cell; I got pure silver snowflakes on the anode side. And I got some weird brown foamy substances on the cathode. I also got a gray, puffy substance on the anode side as well, that I have yet to melt and see what it is. Spent about $20 in coins on this experiment.

Thus my question. In a way, it's a bit like inquarting gold to have the cell run correctly. Silver is otherwise too cheap to use Nitric on; if I were refining gold, I would inquart my gold with silver/copper coins I wanted to refine, then digest in AR, cement the silver on copper, cement the copper with aluminum, and continuously add to my stock of silver and copper for more inquarting. But, alas, I am not refining gold!

I did build my copper cell using http://electrochem.cwru.edu/encycl/art-m02-metals.htm. It has worked OK at parting silver and copper, but I'd really like to read GSP's book that Nick described.

 

[g_axelsson]

I like this idea.

If you have silver copper contact points and similar materials with quite pure silver fused or laminated with copper or brass you should be able to selectively dissolve the copper while leaving the silver part relatively untouched. If you melt it together into an anode it will come out as a fine powder or anode slime .
I would guess that with low enough voltage and a high Cu-sulphate concentration you could remove all copper without touching the silver.

The question of how pure a copper anode has to be for copper purification is probably quite relaxed. The limiting factor is the purity of the electrolyte, not the anode. The less copper in the anode the more often you have to replace the electrolyte. But I guess that there is a limit of at least 75% copper so the other metals in the anode falls off and exposes more copper. Any less purity could easily form a crust and stop the process. Compare it with 75% silver and 25% gold for inquartation. Any higher gold content and some of the silver could be shielded by the gold. It is also a question of what the impurities in the copper is, if it's zinc it would just dissolve into the electrolyte while lead would form a crust.

/Göran

 

[ElectricAngel]

Scott I believe our very own goldsilverpro has a book on silver recovery and refining available from lazersteves site and he has written extensively on the subject here on the forum even posting designs of some of his simplest and best cells.

Thanks, Nick. Having played around a bit with the article I linked from the ElectroChem encyclopedia, I have the bug. I will have to pick up GSP's book. The biggest issue I have is with silver cells: I don't want to use silver nitrate and precious nitric acid unless I have no alternative, thus the idea to refine the copper out of the silver-copper alloy, and get pure silver in the anode slime. There may, however, be no alternative.

 

[ElectricAngel]

I like this idea.

If you have silver copper contact points and similar materials with quite pure silver fused or laminated with copper or brass you should be able to selectively dissolve the copper while leaving the silver part relatively untouched. If you melt it together into an anode it will come out as a fine powder or anode slime .
I would guess that with low enough voltage and a high Cu-sulphate concentration you could remove all copper without touching the silver.

The question of how pure a copper anode has to be for copper purification is probably quite relaxed. The limiting factor is the purity of the electrolyte, not the anode. The less copper in the anode the more often you have to replace the electrolyte. But I guess that there is a limit of at least 75% copper so the other metals in the anode falls off and exposes more copper. Any less purity could easily form a crust and stop the process. Compare it with 75% silver and 25% gold for inquartation. Any higher gold content and some of the silver could be shielded by the gold. It is also a question of what the impurities in the copper is, if it's zinc it would just dissolve into the electrolyte while lead would form a crust.

/Göran

Thanks for the insight, Göran. Of course, the white whale of silver refining is silverplate. If you could melt the silverplated items into an anode, electrorefine the copper out (there would have to be a lot of it), you'd get the zinc and other base metals into the electrolyte, but the silver you were pursuing (along with any gold if you were lucky!) would drop out into the anode slime. I need to get a good guide on copper electrorefining; next stop, LazerSteve's for GSP's book.

 

[NobleMetalWorks]

Thanks, Scott. I had tried Canadian 1968 Quarters (50/50 Cu/Ag) in an electrorefining cell; I got pure silver snowflakes on the anode side. And I got some weird brown foamy substances on the cathode. I also got a gray, puffy substance on the anode side as well, that I have yet to melt and see what it is. Spent about $20 in coins on this experiment.

The weird brown foamy substance is probably copper and whatever other base metals are not being dissolved into solution. The gray puffy substance is probably displaced/cemented silver. By adjusting how often you scrape, or the volts/amps you can minimize the amount of silver that deposits with the anode slime, or is displaced out of solution and turns into floating gray puffy material. Sounds like a case where you are not plating the silver out as fast as it's going into solution, then when the copper is dissolved after it is cementing the silver out. You probably need to back off the amps a little, turning them up seems to plate faster, but it also dissolves silver into solution faster.

Thus my question. In a way, it's a bit like inquarting gold to have the cell run correctly. Silver is otherwise too cheap to use Nitric on; if I were refining gold, I would inquart my gold with silver/copper coins I wanted to refine, then digest in AR, cement the silver on copper, cement the copper with aluminum, and continuously add to my stock of silver and copper for more inquarting. But, alas, I am not refining gold!

It's sort of like inquarting, except when you inquart you do so, so that the silver is no longer protected by the gold from being attacked, and is in enough quantity to be dissolved into solution then you are left with Au as the residual. When we upgrade the content in an electrolytic cell it's so that the refined metal at the cathode is more pure. So it's the same type of concept, but for a different reason. The higher the purity going in, the higher it plates out at the cathode. You can also, again, play with volts/amps to get the metal to plate out more efficiently, and in a more refined state.

Watch out for the floaters, if you get a string of them they can short your cell.

I did build my copper cell using http://electrochem.cwru.edu/encycl/art-m02-metals.htm. It has worked OK at parting silver and copper, but I'd really like to read GSP's book that Nick described.

I figured out my copper cell on my own, but I also fiddled with it a lot to get it to work the way I wanted to make it work. It would be nice to have the numbers to crunch right in front of me while I am doing it, but I'm happy with the results I'm able to get, and the side benefit is that by testing different conditions, settings, solutions and combinations of materials I am learning what to expect and how to adjust dynamically. Even still, I would like to have a good book dedicated to the subject with tables, illustrations and the equations needed to figure proper volts/amps, cathode/anode sizes and surfaces, distances for cathode from anode, etc.

Scott

 

[ElectricAngel]

Thanks, Scott. I had tried Canadian 1968 Quarters (50/50 Cu/Ag) in an electrorefining cell; I got pure silver snowflakes on the anode side. And I got some weird brown foamy substances on the cathode. I also got a gray, puffy substance on the anode side as well, that I have yet to melt and see what it is. Spent about $20 in coins on this experiment.

The weird brown foamy substance is probably copper and whatever other base metals are not being dissolved into solution. The gray puffy substance is probably displaced/cemented silver. By adjusting how often you scrape, or the volts/amps you can minimize the amount of silver that deposits with the anode slime, or is displaced out of solution and turns into floating gray puffy material. Sounds like a case where you are not plating the silver out as fast as it's going into solution, then when the copper is dissolved after it is cementing the silver out. You probably need to back off the amps a little, turning them up seems to plate faster, but it also dissolves silver into solution faster.

I should have been clearer: I was refining 50/50 Silver/Copper in a COPPER electrorefining cell. The only possible metals should have been silver and copper, according to the Canadian mint. I got a spongy gray substance most of the time on the anode side (but occasionally beautiful snowflakes of silver) and usually copper on the cathode side (never used thiourea, so the deposit was, in a word, ugly), but occasionally a spngy substance that was gray on the outside and brown in the middle (and the blue went out of my electrolyte), indicating that normal electrorefined copper was NOT being deposited.

When we upgrade the content in an electrolytic cell it's so that the refined metal at the cathode is more pure. So it's the same type of concept, but for a different reason. The higher the purity going in, the higher it plates out at the cathode. You can also, again, play with volts/amps to get the metal to plate out more efficiently, and in a more refined state.

Yes, well, I was working with an old cell-phone charger; I suspect a serious person would have gotten a proper rectifier to start. I think a 6- or 12-volt battery would work better; better, still, to work with volts and amps controllable. That's coming next.

I did build my copper cell using http://electrochem.cwru.edu/encycl/art-m02-metals.htm. It has worked OK at parting silver and copper, but I'd really like to read GSP's book that Nick described.

I figured out my copper cell on my own, but I also fiddled with it a lot to get it to work the way I wanted to make it work. It would be nice to have the numbers to crunch right in front of me while I am doing it, but I'm happy with the results I'm able to get, and the side benefit is that by testing different conditions, settings, solutions and combinations of materials I am learning what to expect and how to adjust dynamically. Even still, I would like to have a good book dedicated to the subject with tables, illustrations and the equations needed to figure proper volts/amps, cathode/anode sizes and surfaces, distances for cathode from anode, etc.

Scott

According to the link I posted earlier, the following information applies in commercial electrorefining:
"The electrolyte contains 40 grams/liter of copper as copper sulfate and 150 to 200 g/l sulfuric acid and the refining cells operate at ~60oC (~140oF). Small quantities of glue, thiourea and chloride are added to the electrolyte; these compounds adsorb on the copper surface and help to form a dense electrodeposit. A current density of ~200 A/m2 is passed between the negative and positive electrodes and this results in a cell voltage of about 0.28 V. The electrical energy consumption in the copper electrorefining cell is ~0.25 kWh/kg."

Straightening this out for a small cell would do wonders for us both! If you wanted to share your data, I could run a few experiments and post back the results. I won't do this until I have a power supply that allows me to control voltage and amperage, however.

 

[ElectricAngel]

I figured out my copper cell on my own, but I also fiddled with it a lot to get it to work the way I wanted to make it work. It would be nice to have the numbers to crunch right in front of me while I am doing it, but I'm happy with the results I'm able to get, and the side benefit is that by testing different conditions, settings, solutions and combinations of materials I am learning what to expect and how to adjust dynamically. Even still, I would like to have a good book dedicated to the subject with tables, illustrations and the equations needed to figure proper volts/amps, cathode/anode sizes and surfaces, distances for cathode from anode, etc.

Scott

One last thing: My cell consisted of a large glass jar, within which I had two smaller glasses. So, when silver would snowflake off the anode, it would sprinkle down into the glass's bottom. The same is what I wound up doing with the cathode, mostly because my copper deposits, not being smooth, would fall off into the electrolyte when I removed the cathodes. On the anode side, I used pure silver wire to connect the anode to the power source; on the cathode side, copper wire. I used two glasses in the cell with flared tops; bottom diameter about 2.5 inches, top diameter about 4 inches; the glasses were submerged in the electrolyte, with an inch of electrolyte over their tops. I wonder if this caused local-to-the-glass depletion of the electrolyte? Anyway, great fun for a first experiment, but time to get a serious power supply and take another crack at it.

 

[g_axelsson]

ElectricAngel, I didn't suggest to melt silver plate, anyone going after silver plate will spend a lot of time and money chasing very little money. Probably spending more on chemicals than earning in silver.
There is nothing strange with refining copper and recovering silver, every copper refinery is doing it. But to think you could do it on a hobby basis and making money is just wrong.

I was talking about thicker silver contact points, where the silver could be 1-2 mm thick on top of a copper base.

One thing I'm a bit disappointed of this forum is that almost noone is talking about cell voltages. Everyone is getting a battery charger and just hooks it up to an electrolytical cell. That is like trying to drive a car with the accelerator always floored. It might work but you will have problem. To regulate the cell voltage is one of the most important factors in an electrolytical cell. You even write that the cell voltage is close to 0.28V just after you talk about hooking up a 6V or 12V charger to get it to run better. At least you add at the end that you would like to have a regulated supply. There is some hope. :lol:

Electrochemistry is a wonderful area of science and I have a couple of books but I haven't taken the time to learn that subject yet. Some day I will, until then I just continue reading here on the forum and on various sites, learning one small piece at a time.

/Göran

 

[NobleMetalWorks]

It seems like to me most people try to run their cells with too little dissolved metal in solution, and too high volts and/or amps.

Before I start my copper cell, the solution is totally saturated, then as the copper plates out on the cathode it makes room for more to dissolve into solution, or at least that's the idea. If you start off with a solution that isn't saturated, you are going to dissolve other things into solution. Since I was running silver/copper in the cell that were not melted into an anode bar but rather just attached to each other, any silver that did get dissolved was forced back out again. And like I said above, running a pure copper anode after, then taking a small amount and testing with HCl to see if silver chloride is formed, I was able to ensure my solution was just copper 2 sulfate.

There are a lot of reasons why I am leaning strongly towards electrolytic refining, I like the idea of reduced amounts of waste solution, and I love the idea of paying for silver and getting a little Au and other PGMs, rather than paying for gold and getting a little silver and other PGMs. Just makes more sense to me.

Scott

 

[ElectricAngel]

ElectricAngel, I didn't suggest to melt silver plate, anyone going after silver plate will spend a lot of time and money chasing very little money. Probably spending more on chemicals than earning in silver.
There is nothing strange with refining copper and recovering silver, every copper refinery is doing it. But to think you could do it on a hobby basis and making money is just wrong.

Yes, Göran, that's why I called it the "white whale" of refining, after Moby Dick: this great allure that drags you to your doom. The big problem in silverplate is zinc in the brass: it will boil at a lower temperature than silver melts, so melting down a bunch of silverplate to form an ingot for electrorefining can ruin your electromelt furnace! If the silverplate is simply silver over copper, however, it should be possible to heat the plate to 1850 Degrees F, hot enough to melt silver but not hot enough to melt copper, to get the silver off it. With my electromelt furnace, that would cost me 30 minutes, about half a kWh, and 10 cents. Too labor intensive to make any money; one something does for the joy of experimentation.

To regulate the cell voltage is one of the most important factors in an electrolytical cell. You even write that the cell voltage is close to 0.28V just after you talk about hooking up a 6V or 12V charger to get it to run better. At least you add at the end that you would like to have a regulated supply. There is some hope. :lol:

Do you have a recommended electrical power supply that is less than $200 and would allow me to control amperage and/or voltage? I think what I am building towards is a future article here on "building a copper electrorefining cell," and my early experiments were proof that the cell works; now to get the cell to wrok RIGHT.

Thanks for your guidance and encouragement!

Electrochemistry is a wonderful area of science and I have a couple of books but I haven't taken the time to learn that subject yet. Some day I will, until then I just continue reading here on the forum and on various sites, learning one small piece at a time.

/Göran

I have a textbook on Electrochemistry, but have to slowly build my knowledge to use it. It is a science book, not a technology book. At this point, my internal engineer just wants to know the formula...