Waste solutions

[MvK]

Hi guys,

Ive got a couple of questions regarding cementation from my waste tank.

I have been reading the 'dealing with waste' in the Library.

My waste contains HCl and used up Nitric, im dealing with mostly 'clean' ceramic e-scrap. No boards, no burnt stuff/ash. There should be traces of Au, Ag, PGM, and base metals. Before i went to this forum i just saved all the waste liquids in a big drum.

My previous apparatus worked just fine. It was a smaller 20 liter barrel. I bubbled all my waste trough this smaller barrel for at least 48 hours as i read in the Library. I recovered 3 grams of gold, still didnt cement out the copper with iron but saved the waste liquids.

Right now i have upgraded my waste container to a 60 liter barrel. It has a aquarium bubbler, and its own outlet pipe to outside. I have made a spiral from a long piece of 8mm thick copper to cement out trace PM's.

Now im bubbling all this previously processed waste trough the big boy barrel for a week. Just to see if i missed somethint. I took the copper out of the drum before i let it settle, to make it easier to collect the sediment.

The first thing i see is alot of black stuff on the copper. This waste material has already been processed, how can there be so much more PMs in my waste?

Do i keep it bubbling for a longer time? How long time do other members bubble their waste? How can i be sure there are no more PMs left in solution?

What i didnt find on the forums as well, how long does this stuff need to settle? Are we talking overnight, days or weeks?

Thanks,
MVK

 

[Yggdrasil]

Hi guys,

Ive got a couple of questions regarding cementation from my waste tank.

I have been reading the 'dealing with waste' in the Library.

My waste contains HCl and used up Nitric, im dealing with mostly 'clean' ceramic e-scrap. No boards, no burnt stuff/ash. There should be traces of Au, Ag, PGM, and base metals. Before i went to this forum i just saved all the waste liquids in a big drum.

My previous apparatus worked just fine. It was a smaller 20 liter barrel. I bubbled all my waste trough this smaller barrel for at least 48 hours as i read in the Library. I recovered 3 grams of gold, still didnt cement out the copper with iron but saved the waste liquids.

Right now i have upgraded my waste container to a 60 liter barrel. It has a aquarium bubbler, and its own outlet pipe to outside. I have made a spiral from a long piece of 8mm thick copper to cement out trace PM's.

Now im bubbling all this previously processed waste trough the big boy barrel for a week. Just to see if i missed somethint. I took the copper out of the drum before i let it settle, to make it easier to collect the sediment.

The first thing i see is alot of black stuff on the copper. This waste material has already been processed, how can there be so much more PMs in my waste?

Do i keep it bubbling for a longer time? How long time do other members bubble their waste? How can i be sure there are no more PMs left in solution?

What i didnt find on the forums as well, how long does this stuff need to settle? Are we talking overnight, days or weeks?

Thanks,
MVK

For cementing with copper a day or two three should be fine.
Then let it settle completely before siphoning off the liquid.
The sludge/slimes will contain the PMs slipped by from the other processes.
This liquid is then pH adjusted and goes to the next step of treatment.
The copper from the Iron cementing can be saved or disposed of.
And so on, after the description in the waste treatment thread.

 

[eaglekeeper]

I not sure of your situation... but I find handling waste in a smaller amount is better. Many years ago I used a couple 5 gallon buckets and I always dreaded dealing with it, so I've limited myself to 1 gallon containers. Now I treat last weekend refining waste as I'm doing this weekend refining...kind of just move everything over into the next container. The week in between just lets everything cement/settle out...Your situation may be different.

 

[Yggdrasil]

Hi guys,

Ive got a couple of questions regarding cementation from my waste tank.

I have been reading the 'dealing with waste' in the Library.

My waste contains HCl and used up Nitric, im dealing with mostly 'clean' ceramic e-scrap. No boards, no burnt stuff/ash. There should be traces of Au, Ag, PGM, and base metals. Before i went to this forum i just saved all the waste liquids in a big drum.

My previous apparatus worked just fine. It was a smaller 20 liter barrel. I bubbled all my waste trough this smaller barrel for at least 48 hours as i read in the Library. I recovered 3 grams of gold, still didnt cement out the copper with iron but saved the waste liquids.

Right now i have upgraded my waste container to a 60 liter barrel. It has a aquarium bubbler, and its own outlet pipe to outside. I have made a spiral from a long piece of 8mm thick copper to cement out trace PM's.

Now im bubbling all this previously processed waste trough the big boy barrel for a week. Just to see if i missed somethint. I took the copper out of the drum before i let it settle, to make it easier to collect the sediment.

The first thing i see is alot of black stuff on the copper. This waste material has already been processed, how can there be so much more PMs in my waste?

Do i keep it bubbling for a longer time? How long time do other members bubble their waste? How can i be sure there are no more PMs left in solution?

What i didnt find on the forums as well, how long does this stuff need to settle? Are we talking overnight, days or weeks?

Thanks,
MVK

Sorry forgot that part, the settling will take the time it needs, days or week, all depends on how fine it is, temperature and so on.
Just as a precaution one can siphon it to a second container and give it longer there.
Just make sure it is not disturbed.

 

[MvK]

I not sure of your situation... but I find handling waste in a smaller amount is better. Many years ago I used a couple 5 gallon buckets and I always dreaded dealing with it, so I've limited myself to 1 gallon containers. Now I treat last weekend refining waste as I'm doing this weekend refining...kind of just move everything over into the next container. The week in between just lets everything cement/settle out...Your situation may be different.

Well for now im just catching up, i need to dispose alot from a few years of fooling around.. So after im done with the big batch i will be taking smaller amounts. Im using way less acid then i used to so theres no need to keep the big rig.

Thanks for the help

 

[MvK]

Sorry forgot that part, the settling will take the time it needs, days or week, all depends on how fine it is, temperature and so on.
Just as a precaution one can siphon it to a second container and give it longer there.
Just make sure it is not disturbed.

Clear, i will leave it for a week and move on from there.

Once again, thank you!

 

[Martijn]

I have one 12 Liter bucket as a stockpot. I always leave a little solution in it to keep the copper pieces covered. I dont bother cleaning them until i clear out the stockpot.
I toss used pieces of copper in it and leave them in there.
A slow bubbler helps the fine particles settle out faster I've noticed. I usually have clear liquid after one day. Also in the iron pot.
From blue to a pale green in one day.

 

[Marcel]

In order to cement any precious metals (PMs) out of your solution, the ions of those PMs need to come into contact with the copper you placed inside. No contact means no cementing.

Now, to improve the process, consider enlarging the surface area that you offer to those few scattered atoms floating around in your drum. Give them something to hit. A one square meter copper sheet is far more effective than a simple piece of copper from a pipe.

A copper mesh may be even more effective, and so on. You could also try pumping your solution through copper pipes, maybe adding a copper mesh inside.

But do not forget one thing: once one atom of the PMs has cemented out on the copper, the attraction of the Copper (at this very spot) will decrease exponentially. New layers will only stack up very unwillingly. Bare polished Copper is your friend here! Keep it free from grease, paint, oil, and other barriers that will hinder the cementation. Once they have a black layer on them, remove and replace the Copper to harvest other free PM atoms/ions.

Edit: Cementing Precious Metals will follow the order of the Redox Series of Metals. So expect the highest metals in that series to come down first. If your drum contains a "wild" mix of PMs, change those copper elements once they have harvested one type of metal.

Gold will form a deep black layer.
Palladium will form a light gray layer

Sometimes Gold cements onto the copper and Palladium on top.

Silver will not cement out, even if present, due to the high content of chlorides. Silver will drop as Silver chloride but never (1) cement out on copper.

To understand what is going on in your drum, verify the voltages in the right column of the table below. The higher the difference between Copper (or any other metal that you use for cementation), the higher the attraction of those two elements to each other. Since your Copper (0.5V) pipe will not move from its place, the Gold atoms (1.7V) will connect to it like magnets do, since the difference in their potential is around 1.2V, which is a lot, similar to the voltage of an AAA battery.

Once all the gold atoms have found their place on the Copper and the Copper still has free spots, the next metal with the highest difference in voltages will be attracted by the Copper. Some metals will plate out on top of others that have been cemented, but some metals not, depending on the voltage difference they have.
Platinum and Iridium are quite rare in our typical use-case, so the next one will be Palladium with a voltage difference of around 0.4V. This is one-third of the voltage difference between Gold and Copper, so the process will be slower and take longer to cement all the Palladium onto your Copper piece.
The cementing process will stop once there are only free Copper ions and all those base metal ions below it, left.

So, if you use a metal like Iron to cement your metals, all metals above Iron will come down, such as Copper Nickel, Tin etc. togehter with the PMs.

If you make clever use of the Redox Series, you can cement out valuable base metals quite precisely for resale as well. It can also make your waste less toxic.

Here is a simplified Redox Series of Metals to get a better picture. Maybe if that table is need more often the admins could pin it somewhere so only a link will be required. Free of use ;-)

(1) Silver nitrate will cement on Copper, but if any free chloride is present, like in Aqua Regia, Silver nitrate will replace the nitrate ions against the chloride ions which forms Silver chloride and therefore will not cement on Copper

 

[orvi]

Cementing on copper can be peculiar in some ways, as cupric chloride is quite strong oxidizer, and you have always oxygen present. PGMs are very easily re-dissolved after cementation, and whole copper cementing is finely balanced process.

Nobody mentioned it here, but black deposit growing on the copper, and eventually completely disintegrating it is mix of various copper oxides and oxohydroxides. This is completely normal, and it will happen as acid is mostly used up, so oxygen dissolved in the juice oxidize the copper... But it has no free acid to bond with, so it forms some sort of "chloride deprived" deposit - which is obviously insoluble.

That does not say you do not have any values in it. There could be PMs, but usually the cementation is relatively quick process, compared to growth of these black copper "oxide" deposits.

 

[MvK]

In order to cement any precious metals (PMs) out of your solution, the ions of those PMs need to come into contact with the copper you placed inside. No contact means no cementing.

Now, to improve the process, consider enlarging the surface area that you offer to those few scattered atoms floating around in your drum. Give them something to hit. A one square meter copper sheet is far more effective than a simple piece of copper from a pipe.

A copper mesh may be even more effective, and so on. You could also try pumping your solution through copper pipes, maybe adding a copper mesh inside.

But do not forget one thing: once one atom of the PMs has cemented out on the copper, the attraction of the Copper (at this very spot) will decrease exponentially. New layers will only stack up very unwillingly. Bare polished Copper is your friend here! Keep it free from grease, paint, oil, and other barriers that will hinder the cementation. Once they have a black layer on them, remove and replace the Copper to harvest other free PM atoms/ions.

Edit: Cementing Precious Metals will follow the order of the Redox Series of Metals. So expect the highest metals in that series to come down first. If your drum contains a "wild" mix of PMs, change those copper elements once they have harvested one type of metal.

Gold will form a deep black layer.
Palladium will form a light gray layer

Sometimes Gold cements onto the copper and Palladium on top.

Silver will not cement out, even if present, due to the high content of chlorides. Silver will drop as Silver chloride but never (1) cement out on copper.

To understand what is going on in your drum, verify the voltages in the right column of the table below. The higher the difference between Copper (or any other metal that you use for cementation), the higher the attraction of those two elements to each other. Since your Copper (0.5V) pipe will not move from its place, the Gold atoms (1.7V) will connect to it like magnets do, since the difference in their potential is around 1.2V, which is a lot, similar to the voltage of an AAA battery.

Once all the gold atoms have found their place on the Copper and the Copper still has free spots, the next metal with the highest difference in voltages will be attracted by the Copper. Some metals will plate out on top of others that have been cemented, but some metals not, depending on the voltage difference they have.
Platinum and Iridium are quite rare in our typical use-case, so the next one will be Palladium with a voltage difference of around 0.4V. This is one-third of the voltage difference between Gold and Copper, so the process will be slower and take longer to cement all the Palladium onto your Copper piece.
The cementing process will stop once there are only free Copper ions and all those base metal ions below it, left.

So, if you use a metal like Iron to cement your metals, all metals above Iron will come down, such as Copper Nickel, Tin etc. togehter with the PMs.

If you make clever use of the Redox Series, you can cement out valuable base metals quite precisely for resale as well. It can also make your waste less toxic.

Here is a simplified Redox Series of Metals to get a better picture. Maybe if that table is need more often the admins could pin it somewhere so only a link will be required. Free of use ;-)

(1) Silver nitrate will cement on Copper, but if any free chloride is present, like in Aqua Regia, Silver nitrate will replace the nitrate ions against the chloride ions which forms Silver chloride and therefore will not cement on Copper

View attachment 56817

Well, ive learned more then i was asking for, i thought silver would cement out as well!

I forgot to mention my coil of copper is about 4 meters long, i just took the picture of the bottom side to show the cement on the copper. I do expect this to be a 'wild' mix, so i just might take it for another spin after i took the settled stuff out. Just to check if anything else is coming out of solution.

Thanks for the time!

 

[MvK]

Cementing on copper can be peculiar in some ways, as cupric chloride is quite strong oxidizer, and you have always oxygen present. PGMs are very easily re-dissolved after cementation, and whole copper cementing is finely balanced process.

Nobody mentioned it here, but black deposit growing on the copper, and eventually completely disintegrating it is mix of various copper oxides and oxohydroxides. This is completely normal, and it will happen as acid is mostly used up, so oxygen dissolved in the juice oxidize the copper... But it has no free acid to bond with, so it forms some sort of "chloride deprived" deposit - which is obviously insoluble.

That does not say you do not have any values in it. There could be PMs, but usually the cementation is relatively quick process, compared to growth of these black copper "oxide" deposits.

Interesting, theres always more to learn.. I will post results after the week is finished.

Thanks!

 

[MvK]

I have one 12 Liter bucket as a stockpot. I always leave a little solution in it to keep the copper pieces covered. I dont bother cleaning them until i clear out the stockpot.
I toss used pieces of copper in it and leave them in there.
A slow bubbler helps the fine particles settle out faster I've noticed. I usually have clear liquid after one day. Also in the iron pot.
From blue to a pale green in one day.

Thanks Martijn, after i processed the waste that i still have i will definitely do that. The big barrel will be the waste pot, the smaller one the stockpot.

 

[Yggdrasil]

Well, ive learned more then i was asking for, i thought silver would cement out as well!

I forgot to mention my coil of copper is about 4 meters long, i just took the picture of the bottom side to show the cement on the copper. I do expect this to be a 'wild' mix, so i just might take it for another spin after i took the settled stuff out. Just to check if anything else is coming out of solution.

Thanks for the time!

If there is dissolved Silver , Yes it will cement out Silver.
But solutions containing Chloride will not dissolve Silver.

 

[Martijn]

Well, ive learned more then i was asking for, i thought silver would cement out as well!

You could have a separate stockpot for silver nitrate waste.
Actually, you should not have any silver nitrate waste. Convert it into silver chloride and reuse the freed up nitric.

 

[MvK]

You could have a separate stockpot for silver nitrate waste.
Actually, you should not have any silver nitrate waste. Convert it into silver chloride and reuse the freed up nitric.

Well,
Yes, my new setup had its own nitric waste container. I was thinking to cement that one out with copper as well, but i didnt know i can reuse the nitric.. Please explain me your method

The metals in the liquid im working on now are unknown, there could be anything so im just trying to get it all before moving to the next step.

 

[Yggdrasil]

Well,
Yes, my new setup had its own nitric waste container. I was thinking to cement that one out with copper as well, but i didnt know i can reuse the nitric.. Please explain me your method

The metals in the liquid im working on now are unknown, there could be anything so im just trying to get it all before moving to the next step.

Silver Nitrate is easy, mixed Nitrate not so much.

 

[Martijn]

Converting a nitrate salt into a chloride or suphate salt recreates nitric acid in solution.
Look for posts from lazersteve on reusing nitric.
I evaporated 9 L of mainly copper nitrate into crystals and that's ready to get some H2SO4 added for reuse.
You can calculate how much sulfuric you need and freeze out the copper sulfate crystals.
You do need to understand stoichiometry, chemical notations, density and mol weight to calculate it.
The obtained HNO3 is dilute but usefull. It can be concentrated to the azeotrope but that's hardly ever required.

 

[nickton]

In order to cement something it must be in an acidic solution, and not ph neutral I think. Does cementation change the acid's ph? And especially when using a bubbler, what prevents the cemented material from going back into solution in the still acidic liquid?
Just wondering

Oh yes. Another thing: If one uses lead for cementation, does any lead go into solution, thus leaving a lead containing liquid remnant?

 

[nickton]

Also. How do chloride solutions get dissolved silver if they don't dissolve silver? People extracting gold only use ap (a chloride solution), so how does the silver get in there before using ar to later refine I wonder?
There should be no silver chloride around by the time one uses ar, yet I often hear of problems with it at that point.

 

[FrugalRefiner]

In order to cement something it must be in an acidic solution, and not ph neutral I think. Does cementation change the acid's ph? And especially when using a bubbler, what prevents the cemented material from going back into solution in the still acidic liquid?
Just wondering

A cemented metal can go back into solution. Palladian in particular can do so.

Oh yes. Another thing: If one uses lead for cementation, does any lead go into solution, thus leaving a lead containing liquid remnant?

I've never heard of anyone using lead to cement other metals out of solution, but it would have to go into solution to cement out another !etal.

Dave