Selective electroplating

[Mschindler300]

I'm working on a small scale method to pm recovery by plating metals out in stages my plan is to incinerate the high grade Pcb boards and cast the mixed alloy into a Electrode at this point I should be able to move down the line of tank till all I have left is a gold electrode I'm going to do this at a real small level. copper was my first tank I used a pure copper Cathode in copper sulfate electrolyte I'm working on the next tank which will be silver think thum cell I gonna hit the books and do some research


Thank you
Matt S

 

[Harold_V]

It doesn't work that way. When you part copper in a sulfuric copper cell, the other elements are dropped as slimes. They do not go in to solution. If they are high enough in content to not slough off as slimes, the cell won't work because copper will be isolated by the thick skin of non-copper metals remaining.

Be aware, if your anodes are not extremely high grade copper, the cell will work only briefly, before beginning to create soft copper which does not adhere to the cathode. In the end, your electrolyte will have been heavily contaminated by base metals , with the values in the bottom, mixed with copper that has shed from the anode.

Harold

 

[NoIdea]

I'm working on a small scale method to pm recovery by plating metals out in stages my plan is to incinerate the high grade Pcb boards and cast the mixed alloy into a Electrode at this point I should be able to move down the line of tank till all I have left is a gold electrode I'm going to do this at a real small level. copper was my first tank I used a pure copper Cathode in copper sulfate electrolyte I'm working on the next tank which will be silver think thum cell I gonna hit the books and do some research


Thank you
Matt S

Evening, mschilndler300 – The system I am using is similar, with less smoke than direct incineration, end product, if done correctly, is a collection of small metal alloy beads of varying composition, and a powder containing metal, metal oxides, silica, PM’s, and what ever else that may contaminated the mix.

The beads I melt into a 4inch x 4inch x ½ inch plate, this is the anode.

The cell is split in two by a semi-permeable membrane made of PVC clear plastic wrap, kitchen type. Electrolyte is old battery acid and copper sulphate. Power is a 12VDC battery charger, current unknown.

Harold is correct about the pacifying of the anode due to slime build-up, I run the cell for 12hr periods at which time I carefully take the anode out of the cell and scrub it down with one of the kids toothbrush :mrgreen: . This also helps build up of slime in the cell.

Harold, you got it right again with the copper falling off the cathode, I take the cathode out after the anode and scrub this down as well. After the anode has dissolved enough, the cell is emptied of its contents into separate containers to settle. I have found that the cathode side of the cell saturates with cation’s (dark green/brown/blue) while the anode side is a pretty copper sulphate blue. I save the anode side for the next batch and remove as much as the sulphuric acid from the cathode side, then precipitate with wood ash extract (alkali)

As for the powder left over after incineration, well I’m half way through solving that one, at the end of one of my experiments I ended up with a cobalt blue solution, interesting, very interesting.

I have only processed the beads, the resulting slime needs to be dried, incinerated and processed by the methods provide by this forum.

Good luck

Deano

 

[Mschindler300]

Thanks for your reply looks like IM gonna hit the books some more i Missed a few key Points

im using labatory grade anodes figured it was my best bet

Thank you guys

I keep you filled in on my progess

 

[Acid_Bath76]

I am constantly amazed what I find on this forum. Deano, could you take a couple pics of your set-up? This really sounds interesting. Of course, before I construct anything like this, I'll need to read up on my chemistry and ... is it Faraday?

 

[NoIdea]

Afternoon All – As requested, here is a photo of my cell, nothing special. Depth of the cell is important, keeping the deposits away from the anode and cathode, also the membrane is only two thirds the ways down so the deposits do not form a bridge between electrode departments.



Emptying the cell is easy, just tip and pour into containers at the same time.

I like to keep things simple; I just don't understand why people complicate things.

I encountered the problems with the cell as mentioned above, so i suggest if you do try this cell, try and stick to the description outlined.

Have fun.

Cheers

Deano

 

[pesco]

Few questions Deano:
1) membrane 2/3 the way down, you mean you have a gap at the bottom with no membrane ?
2) membrane itself, is that the cling foil you are using ?


I'm guessing you are using pyrolysis. If so I will have some questions in a month or so when I'll be ready to set up a rig :mrgreen:
Side note -> if you doing pcb's the Co comes from Kovar (around 17% Co), great deal of pins and connectors are made of it. The photo you posted in other topic -> beautiful colour :mrgreen:

 

[NoIdea]

Few questions Deano:
1) membrane 2/3 the way down, you mean you have a gap at the bottom with no membrane ?
2) membrane itself, is that the cling foil you are using ?


I'm guessing you are using pyrolysis. If so I will have some questions in a month or so when I'll be ready to set up a rig :mrgreen:
Side note -> if you doing pcb's the Co comes from Kovar (around 17% Co), great deal of pins and connectors are made of it. The photo you posted in other topic -> beautiful colour :mrgreen:

Hi Pesco – Yes the membrane does indeed goe only 2/3’s way down. When the system is well on the way, copper will fall off the cathode and collect on the bottom of the cell, likewise, anode mud will also accumulate on the bottom. I have found in the past that if the membrane does go all the way to the bottom a there is a chance a short can occur between cells, between cell bottom deposits. Hope that make sense?

And yes the membrane is made of clear film, the one in the picture needs replacing.

Cheers


Deano

 

[Acid_Bath76]

Deano,

Any new data? What's the word over there?

 

[NoIdea]

Hey Acid – Assuming it was me the question was aimed at, no data yet to speak of.

I have at least a dozen or more things going on at one time, I have 17yrs of experimental solutions to deal with, along with the mountain of waste generated.

When I plan to do more electro-winning, I’m going to use a Terracotta pot for the anode compartment and stainless steel bowl for cathode, and if that works then the other cell will go west.

I am boiling down my AR, yes, I said boil, it is a closed system as I want to recover my acid for re-use. I will be collecting data in terms of gold chloride evaporation through out the process. I am curious as to when the gold becomes volatile and starts to distil over with the acid. Due to the refluxing nature of my distillation unit, I doubt I’ll get much carry over until higher a concentration is achieved.

This is in no way an attempt to over mine Harold and his constant reminder, not to boil your gold bearing solutions. It’s more of an attempt to re-enforce his warnings and provide proof beyond doubt.

I’ll post a new topic once I have enough information on both the AR boiling and the Terracotta cell.

Cheers

Deano

 

[capt_dugout]

Few questions Deano:
1) membrane 2/3 the way down, you mean you have a gap at the bottom with no membrane ?
2) membrane itself, is that the cling foil you are using ?


I'm guessing you are using pyrolysis. If so I will have some questions in a month or so when I'll be ready to set up a rig :mrgreen:
Side note -> if you doing pcb's the Co comes from Kovar (around 17% Co), great deal of pins and connectors are made of it. The photo you posted in other topic -> beautiful colour :mrgreen:

Hi Pesco – Yes the membrane does indeed goe only 2/3’s way down. When the system is well on the way, copper will fall off the cathode and collect on the bottom of the cell, likewise, anode mud will also accumulate on the bottom. I have found in the past that if the membrane does go all the way to the bottom a there is a chance a short can occur between cells, between cell bottom deposits. Hope that make sense?

And yes the membrane is made of clear film, the one in the picture needs replacing.

Cheers


Deano

are you saying that there is a "gap" under the membrane or is it glass or similar divider to seperate cell sides?

P.S. how do I upload pics just out of curiousity ? I have looked but must be overlooking the info somehow

 

[Gold]

When I plan to do more electro-winning, I’m going to use a Terracotta pot for the anode compartment and stainless steel bowl for cathode, and if that works then the other cell will go west.

Cheers

Deano

That won't work Deano. The ions will not be able to penetrate the micron pore size (.5 micron) of the terracotta pot. What you are describing is a fizzer cell.

 

[Gold]

I've ordered samples from http://www.membranesinternational.com/ in the past to do experiments with. Look at there website and find one you need and fill out the sample request forum. I have ordered multiple samples in the past and they are always happy to send them free of charge and they pay the postage also.

 

[NoIdea]

That won't work Deano. The ions will not be able to penetrate the micron pore size (.5 micron) of the terracotta pot. What you are describing is a fizzer cell.

Hi Gold - not to be rude but ions are messured in the picometers which is about a million times smaller that a micrometer, if water can soak through it so will the ions pass through.

Deano

 

[butcher]

I thought the dissolved ions will pass through the pot, but not the metals that are not dissolved (anode sludge), there is a patent by shor that uses salt and a gold anode, I believe GSP suggested a Coors cup (looked similar to crucibles) with 0.5 micron pore size, bagging the anode would still be something I would try to keep values from clogging pots pores.

 

[Palladium]

I made the post above Deano. The reason I say this is because I have been conducting experiments that deal with these principals. I can’t break all the science down, I’m not quiet that smart, but like Harold says “I don’t know why it works, I just know it works.”

Here’s what I know, maybe you can add some to it because I’m very interested in this field of research for my project.

When you say ion you are speaking singular terms. True ion’s are small if you’re talking one atom. But we are talking complex chemical structures like AuCl4, CuCl4, and so on. When you start determining complex ion size you have to take into account the size of an ion depends on its nuclear charge, the number of electrons it possesses, and the orbital’s in which the outer-shell electrons reside and the way they are complexed. All the sudden they aren't small.

In the fizzer cell the anode and cathode are separated by a semi permeable membrane. In the old days this was accomplished with everything from German porcelain, asbestos, cellophane, even concrete, plaster, and terracotta. The purpose of this is to obtain a micron rating from .2 - .5 microns to stop the migration of the complexed ions. The anode is made of gold and reduces the saltwater from NaCl to Cl allowing the anode to dissolve. Where it not for the membrane the gold would deposit at the cathode. That’s what the Wohlwill process does, but without a membrane. The sodium ion is then able to cross the membrane and be converted to sodium hydroxide at the cathode. The sodium hydroxide being a complex ion cannot cross back through the membrane or if it did it would cause you metals to precipitate from the chloride solution. The same principle applies to the chloralkali process but instead of an inert anode producing cl we are using a gold anode and complexing it with cl. Cathodes can be made with everything from stainless steel or graphite, to titanium.

The cup serves two purposes in the shor design. The first is to block metal ion migration and the second is to serve as an easily removable vessel so you can transfer the liquid for filtering. All the gold in the solution will be in the cup. The reason to bag the anode in this application just serves to stop contaminates from fouling the solution which will lead to pore clogging which will stop the cell up. It also helps to catch stones or silver chloride.

Not sure exactly what you had in mind with the terracotta cup just thought I would let you know.

 

[NoIdea]

Hi Palladium – I was only planning to use the terracotta pot for electro-stripping of a multi-metal alloy, made from such metals found in e-waste. The pot will house the anode.

When I was talking about ions, well that’s how soluble metal salts behave in solution, as cations and anions (a bit more complex from complexes), therefore if one was to have a cell with a semi-permeable membrane separating the anode and cathode (both are inert for this scenario), and you were to put a concentrated copper sulphate solution into both compartments, after applying a suitable voltage/current, the cations will migrate through the membrane towards the cathode and the anions will migrate towards the anode. Any insoluble material will remain in their respective compartments.

I noticed when I was running my cell; the anode compartment was a very pretty blue colour whereas the cathode compartment was a dirty dark green browny colour, possibly due to nickel and iron in solution, plus other of course.

There is a method out there somewhere that uses this approach to regenerate sulphuric acid by electrolytic separation of cations and anions

The patent you referred to has a membrane which functions the roughly the same, except it is only semi-permeable under certain conditions, quite selective for that purpose it seems.

I don’t need anything that fancy.

Thanks for the heads up on using a bag with the pot.

Cheers

Deano

 

[Geo]

when you get it up and running please post a few photos. when you say multi metal alloy anode does that mean you melt all the metals together into one piece to form the anode or just a select few?

 

[pesco]

Hi Pesco – Yes the membrane does indeed goe only 2/3’s way down. When the system is well on the way, copper will fall off the cathode and collect on the bottom of the cell, likewise, anode mud will also accumulate on the bottom. I have found in the past that if the membrane does go all the way to the bottom a there is a chance a short can occur between cells, between cell bottom deposits. Hope that make sense?

And yes the membrane is made of clear film, the one in the picture needs replacing.

Cheers


Deano

Deano,
good explanation, but I have few more questions :mrgreen:
1) if the membrane is 2/3 down with gap on the bottom then the liquids do mix anyway, i don't see a point of membrane as such, you could use sheet of glass, acrylic or any inert material; the point of using a membrane is to prevent mixing liquids while allowing ions to pass through
2) if there is a undivided space on whole bottom of the tank then it would cause short circuit after sludge/copper droppings ( :mrgreen: ) build up; dividing the area would prevent short circuit as there would be no electrical continuity even if the sludge or copper droppings reach both cathode and anode - they are still electrically isolated by membrane

I can't understand how dividing both compartments causes short when leaving it undivided prevents it.

Please don't get annoyed with me for digging the subject - I just want to get the concept and its benefits :mrgreen:

 

[NoIdea]

Deano,
good explanation, but I have few more questions :mrgreen:
1) if the membrane is 2/3 down with gap on the bottom then the liquids do mix anyway, i don't see a point of membrane as such, you could use sheet of glass, acrylic or any inert material; the point of using a membrane is to prevent mixing liquids while allowing ions to pass through
2) if there is a undivided space on whole bottom of the tank then it would cause short circuit after sludge/copper droppings ( :mrgreen: ) build up; dividing the area would prevent short circuit as there would be no electrical continuity even if the sludge or copper droppings reach both cathode and anode - they are still electrically isolated by membrane

I can't understand how dividing both compartments causes short when leaving it undivided prevents it.

Please don't get annoyed with me for digging the subject - I just want to get the concept and its benefits :mrgreen:

Hi Rico – No problems with questions, questions are good, less mistakes and less room for error.

The membrane is constructed of two parts, the bottom part which is a solid piece of plastic, acting as a barrier, and then there is the top 2/3rds of the membrane made from clear wrap. The bottom portion will not allow a current to pass through, while the top portion will. The membrane will only let cations and anions pass through, making sure that the particulate matter remains where it should.

The problem occurs in the cathode compartment, as the copper is stripped from solution, it loosely deposits it’s self to the cathode, some stays adhered to the cathode and some falls off and lands on the bottom of the cell.

As the copper deposits increases on the bottom of the cell, it grows in height, it runs the risk of eventually making contact with the cathode, if this occurs them the bottom deposits become part of the cathode, now, if the copper deposit just happens to be in contact with the membrane, the copper deposit will start to migrate through the membrane to manifest itself on the anode side of the two compartments. Path of least resistance. This is why I had the bottom portion of the membrane installed, bin there done that, surprised the hell out of me when it did to it. :shock:

Hope that helped,

Regards

Deano