One more question about processing material in cell

[frank-20011]

hello everyone,

since two years i've collected differnt materials and assorted it for different processes, only for hobby purposes.

the ap stuff is almost processed and one of the other portions is the stuff for the sulfuric stripping cell. i've stored it in an other pot.
the problem with these stuf is the following: there are high and low grade stuff in the pot, no problem but there are older copper-clamp contacts mixed in it.
it must be 5kg and so there are thousends and hundred of thousends of little parts and so it must be almost impossible to take these little copper contacts out of the whole mass.

why i think i have to take them out? for testing them i have processed a few of these clamps in AP, together with plated boards, and long, long after the boards these little clamps are gone and so i can take out the gold plating from them: it is as almost as thik like aluminium foil, really: between thumb and forefinger you can roll these little flakes of gold to small tubes.
Normal gold flakes from AP desplated boards you can pulverize to almost nothing than a golden glimmer between two fingers.

O.K. my concern about processing the whole mass together in the cell is that thinner plating go off very fast in the sulfuric and so i could think the process is ready but the much thicker gold from these copper contacts is still there, i can't see it and so it goes into waste with the most, complete deplated parts.

-Should the cell run 10...20...30 mins more for beeing safe?
-should i really separate out the copper-clamp-contacts to process them extra...this could take days
-or is it no problem...the laying in the cell and when the gld is gone every part stops for itself

very thump greenhorns mistake but i really do not think that these gold plating is so MUCH thicker than others.

a short other question about the thickness of gold plated parts in the copper basket: how many layers of parts can lie on top of each other? my concern about this is that the upper layer can be deplate and after it they buld an electrical cage and so the parts under them do not start with deplating....is this concern real or starting the parts under the top to deplating if the gold of the higher parts is dissolved?

Thanks a lot, regards, frank!

 

[goldsilverpro]

hello everyone,

since two years i've collected differnt materials and assorted it for different processes, only for hobby purposes.

the ap stuff is almost processed and one of the other portions is the stuff for the sulfuric stripping cell. i've stored it in an other pot.
the problem with these stuf is the following: there are high and low grade stuff in the pot, no problem but there are older copper-clamp contacts mixed in it.
it must be 5kg and so there are thousends and hundred of thousends of little parts and so it must be almost impossible to take these little copper contacts out of the whole mass.

why i think i have to take them out? for testing them i have processed a few of these clamps in AP, together with plated boards, and long, long after the boards these little clamps are gone and so i can take out the gold plating from them: it is as almost as thik like aluminium foil, really: between thumb and forefinger you can roll these little flakes of gold to small tubes.
Normal gold flakes from AP desplated boards you can pulverize to almost nothing than a golden glimmer between two fingers.

O.K. my concern about processing the whole mass together in the cell is that thinner plating go off very fast in the sulfuric and so i could think the process is ready but the much thicker gold from these copper contacts is still there, i can't see it and so it goes into waste with the most, complete deplated parts.

-Should the cell run 10...20...30 mins more for beeing safe?
-should i really separate out the copper-clamp-contacts to process them extra...this could take days
-or is it no problem...the laying in the cell and when the gld is gone every part stops for itself

very thump greenhorns mistake but i really do not think that these gold plating is so MUCH thicker than others.

a short other question about the thickness of gold plated parts in the copper basket: how many layers of parts can lie on top of each other? my concern about this is that the upper layer can be deplate and after it they buld an electrical cage and so the parts under them do not start with deplating....is this concern real or starting the parts under the top to deplating if the gold of the higher parts is dissolved?

Thanks a lot, regards, frank!

Most of the current is applied to the outside of the pile. To strip the parts in the middle of the pile, you either wait forever or you need to somehow stir or shift the positions of the parts. The best thing is to somehow make a tumbler that you can crank by hand every minute, or so, and move the parts around a bit. For more than a small batch of parts, the copper screen basket was a terrible idea to start with. However, in 9 years, no one has come up with anything better.

To answer your question, one layer of parts would be the best. However, that is impractical.

If you were to wire one 30 microinches gold plated pin, with some small copper wire, and hang it in the sulfuric at about 6 to 8 volts, it would likely strip in one minute, or less. I used to strip gold braze, which is about 35 times thicker than any plating you'll be stripping, from individually racked parts in 20 minutes. I didn't exceed a current of 4A per gallon of solution. Anything higher would have overheated the solution.

With more than 1 layer of parts, it will take more time. The longer you take to strip the parts and/or you allow the solution to get hotter than about 105F, the more copper/nickel will dissolve and this causes recovery problems and lowers the life expectancy of the solution. To have success, move the parts around quite often to alter their positions in the pile.

 

[frank-20011]

Hello,

and thanks for your answer!

i know the reports about the "tumbler deplating cells"....

Mhm...not good but for hobby purposes only and for 2,5kg a year it's maybe acceptable to use a copper basket but these basket should have not a little surface, the acid vessel should be wide and long instead of high, so there can be placed a bigger mesh and so it's easyer to spread out the conectors, pins, etc.!


O.k. to my other question: i've red in your lines, it's almost the only way to take the thicker plated parts out of the millions of thinner plated ones, by hand and then, i have to process them alone.
these copper clamps are very small, theyer gold plated tops are maybe only 2,5mm x 4mm, two times a clamp.
i will cut of the golden tops from these clamps and than i'll process them in HNO3 (to safe acid).

how much acid (53%) dissolve how much Cu?

nice evening/night/morning/day to everyone of you!

 

[goldsilverpro]

Hello,

and thanks for your answer!

i know the reports about the "tumbler deplating cells"....

Mhm...not good but for hobby purposes only and for 2,5kg a year it's maybe acceptable to use a copper basket but these basket should have not a little surface, the acid vessel should be wide and long instead of high, so there can be placed a bigger mesh and so it's easyer to spread out the conectors, pins, etc.!


O.k. to my other question: i've red in your lines, it's almost the only way to take the thicker plated parts out of the millions of thinner plated ones, by hand and then, i have to process them alone.
these copper clamps are very small, theyer gold plated tops are maybe only 2,5mm x 4mm, two times a clamp.
i will cut of the golden tops from these clamps and than i'll process them in HNO3 (to safe acid).

how much acid (53%) dissolve how much Cu?

nice evening/night/morning/day to everyone of you!

I have no idea what those "clamps" look like. Photo or link?

With a copper mesh basket, which you're almost forced to use, I would agree it would be best to maximize the area the parts are spread out in and make the pile shallow. I would run small batches and figure a way to safely mix them often. If everything you have is plated, I wouldn't worry about separating stuff. There is no plating too thick to take more than a few minutes to strip if fully exposed to the current. What slows things down is piling parts on top of each other without often mixing them up. Current flows along the path of least resistance.

With 70% nitric, 1 gallon of 50/50, nitric/water, by volume, will dissolve 1 pound of copper in an open-top container. With 53%, to end up with this same strength, use 65% nitric plus 35% water, by volume. It's usually better to use distilled water, especially if there is any possibility of silver present.

After the gold strips, the Cu or Ni exposed tends to passivate (converts to a non-metallic surface - usually an oxide) from the oxidizing reaction at the anode and will block the flow of current. The usual way to determine the completion of the stripping is when the V is , say, 6-12, and the current decreases to zero or just a smidgeon off zero. When you strip the gold, it becomes a metal powder which is heavy and will tend to sink. However, if you allow this powder to build up too high in the solution, a lot of it will be suspended in the whole solution and, being metallic, it will conduct electricity somewhat and cause a partial short between anode and cathode. Thus, the current won't go to zero, no matter if the gold is 100% stripped. When this happens, you know it's time to harvest the gold from the solution.

What do you plan on using as a power supply?

Wear gloves and a full face shield. The burns can be quite bad.

 

[nickvc]

I wouldn't use the cell for this, it's too hit and miss!
I'm not a fan of either process but wouldn't AP be a safer and more reliable method to recover your gold. It's simple takes a little time but is far safer and with the use of stannous almost fail safe.
The equipment needed is easily available and cheap, not to be done in the house or garage but easy to transport outside, keep kids and pets away!

 

[frank-20011]

Hello,

i "work" with chems since i am 12, for example i make my own fertilizer, growing (edible) mushrooms, etching c. boards and i have studied agriculture with a little bit of lab practice.

no good link for such a connector but it looks like an "U" (soldered to the board on a little solder tail on its bottom), that is the female part and the male part looks like an "I" which pluged into the "U"....the upper tips of the "U" are gold plated.

one benefit by working with a basket is the "ittle" acid volume instead to an basket like anode.

"After the gold strips, the Cu or Ni exposed tends to passivate (converts to a non-metallic surface - usually an oxide) from the oxidizing reaction at the anode and will block the flow of current. The usual way to determine the completion of the stripping is when the V is , say, 6-12, and the current decreases to zero or just a smidgeon off zero. When you strip the gold, it becomes a metal powder which is heavy and will tend to sink. However, if you allow this powder to build up too high in the solution, a lot of it will be suspended in the whole solution and, being metallic, it will conduct electricity somewhat and cause a partial short between anode and cathode. Thus, the current won't go to zero, no matter if the gold is 100% stripped. When this happens, you know it's time to harvest the gold from the solutio"

yep, i've red a lot about different cells of different forum users and i've looked a lot of videos (vids from forum members but others, non members too)...so i think i am -almost- intimate with the process in cells, not into the last chemical/physical secret but it should be enough to build a first little cell, an to use it with a few pins, for the first try.

the electric supply: mhmm, i have a little variac (0-250V and 15A, i only want to use a simple diode circuit for rectifying) and i have some ATX power supplys, for example with 12V/40A but as everybody knows they have more different exits: 3,3V, 5V, 12V and so i can change the voltage with controlling processes at the cell with the different voltages.
Multimeters, lab themometers, glass rods, vessels and so on and so on i have too.

induced my hobbies i do not have to buy any chemical or protective wear...only a face shield i do not have, i ever use a gas masket but working with it isn't comfortable...

@nick: these thicker plated copper contacts are mixed in my other plated parts and the most of them aren't made of copper, so if i want to process them in AP (other parts aren't preferable for AP) i have to take them out of 5kg of other pins, by hand.
i thing these copper contacts are only one handful...

the reason why i have some concern about processing these few copper parts together with so MUCH and so much thinner plated parts in the cell is if current decreases to zero or "just a smidgeon off zero" i could think: o.k. job is done, lets take the parts out and let em wash but maybe on these few copper parts the gold isn't gone like the gold from the more and thinner plated parts.

O.k., if i make the first test runs i will take a very close look for my "copper clamp contacts" and their plating, their fat plating...hehe, yesterday i've fished two of these thick foils out of my test AP (the test AP only for these strange clamps) and yes: it's easyli possible to roll them to a little nub, show me something like that with foils from a, a, a graphic card!

"After the gold strips, the Cu or Ni exposed tends to passivate (converts to a non-metallic surface - usually an oxide) from the oxidizing reaction at the anode and will block the flow of current"

and i thought about these fact, every de-plated part stops to be in process (cause its surface doesn't sends electrons in the electrolyte again) and so the parts laying under these passivated parts working untill they are deplated too, the the parts under them and so on.....

regards, frank!