Old dirty solutions

[steveonmars]

Sorry for the long post. I haven't posted on here in many years. I'm been disabled for about 20 years. I started doing e waste about 15 years ago but never got very far along before I had to put it all on hold for health reasons. I'm finally getting back to it and have some 2 liter beakers half full of very dark acidic solutions, probably from HCL/Peroxide. They were covered while in storage. Most test positive for gold with stannous but I don't remember what exactly is in these solutions or where I left off with anything. I don't think I would have used nitric back then but can't completely rule it out. I tried adding SMB to a couple beakers a couple days ago and let them sit but the liquid is so dark I can't even tell if anything dropped out and the stannous still changes color. I don't know if the gold dropped out and then went back into solution or what happened or if there's powder sitting on the bottom. The solution is too dark to see anything. What would be the best way to go forward with these solutions to clean them up and recover the gold? I don't have nitric now and don't know where to get it where I live so I'd like to avoid using that if I can at least for now. I think I need to filter it all but then I'll just have over a gallon of liquid sitting in a bucket that I still don't know what to do with it. Any help would be greatly appreciated. Thank you.

 

[FrugalRefiner]

Welcome back!

I would treat them like a stock pot.

First, decant all the liquid you can, filtering the last of it but leaving the bulk of the sediment in the beakers. Treat the liquid by cementing; see When In Doubt, Cement It Out.

Then treat any solids as you would with any solids from a stock pot. I'd use HCl first. That should dissolve any copper chloride and similar base metals. Then, if there is any residue left, try HCl and bleach or HCl and hydrogen peroxide. Since they're already powders, you shouldn't need nitric. Drop any gold with the reducing agent of your choice.

Of course, test along the way with stannous to make sure you're getting all the gold.

Good luck with it!

Dave

 

[steveonmars]

Thank you for the quick answer. I do have a stock pot going from solutions that tested negative so I'll add SMB to the other beakers and filter everything out. I'll then add all the extra solution to my stock pot, or maybe a separate one with some copper. Then treat all the solids from the stock pot(s) and filters together. Sound good so far?

Even with all the reading and videos to get back on track I still a couple questions though. How long does it take for everything to cement out on the copper in the stock pots before I can turn the air pump off and let it settle? With the liquids in the beakers being so dark should I dilute everything before I try to cement anything out so I can see what's happening? Can I add too much SMB since I don't really know what's in solution to begin with? I'm still trying to relearn all of this so sorry if this has all been covered somewhere before and I haven't seen it yet.

 

[FrugalRefiner]

I wouldn't bother with the SMB step. Any values in solution will cement out on the copper. No need to add extra chemicals at this point.

Even with all the reading and videos to get back on track I still a couple questions though. How long does it take for everything to cement out on the copper in the stock pots before I can turn the air pump off and let it settle?

When it tests negative with stannous. Then, let it run just a little longer just to be sure.

With the liquids in the beakers being so dark should I dilute everything before I try to cement anything out so I can see what's happening?

It won't hurt, but it will add a bit of volume to the waste solutions to be treated later.

Can I add too much SMB since I don't really know what's in solution to begin with? I'm still trying to relearn all of this so sorry if this has all been covered somewhere before and I haven't seen it yet.

Again, I wouldn't bother adding SMB at this point. When In Doubt, Cement It Out.

Dave

 

[steveonmars]

Thank you again, that make more sense now. When you said "When In Doubt, Cement It Out" you meant in the stock pot with copper, not in the beaker with SMB. It looks like it goes in the stock pot for now. I didn't even think about testing the stock pot with stannous. Good thing I'm in no hurry, I can take my time and hopefully get it right in the long run.

 

[Golddigger76]

Thank you again, that make more sense now. When you said "When In Doubt, Cement It Out" you meant in the stock pot with copper, not in the beaker with SMB. It looks like it goes in the stock pot for now. I didn't even think about testing the stock pot with stannous. Good thing I'm in no hurry, I can take my time and hopefully get it right in the long run.

Something that I would like to add is if your stannous chloride is as old as your waste solution you should consider making or buying some to be certain that you are seeing gold and any other precious metals.

Stannous chloride will go bad after several years.

 

[Martijn]

Most test positive for gold with stannous

was this a brown, black or purple spot? It would be a waste of time trying to get gold if it was only copper.
the stockpot will take care of it anyway.

 

[steveonmars]

Something that I would like to add is if your stannous chloride is as old as your waste solution you should consider making or buying some to be certain that you are seeing gold and any other precious metals.

Stannous chloride will go bad after several years.

I did make new stannous when I started getting all of this back out so that's new. I use tin sinkers and they work really well as far as I can tell.

I just tested my one stock pot and it turned a darker brown color. The solution in the stock pot is a dark green to begin with. It didn't turn purple or black so I don't know if there's any gold in solution but I'm going to keep the bubbler going for a while longer just to be sure. I'm not sure what is in all of these old solutions so I don't know what the dark brown might mean. That bucket has been going for a few weeks now and I'm starting a new stock pot with all the old solutions that are in the beakers. I've been slowly filtering all of that and saving the filters for later. I'll see what that looks like in a few weeks or so.

I can't believe all the stuff I had sitting there for all those years that I can't even remember what most of it even is. I know I have a good amount of black powder in a little sulfuric acid in one beaker from my reverse electrolysis cell I was running back then. I have quite a bit more plated stuff to run in that again so at least I know what that is!

Thanks again for all the help. I'm enjoying getting back into this again.

 

[Golddigger76]

I did make new stannous when I started getting all of this back out so that's new. I use tin sinkers and they work really well as far as I can tell.

I just tested my one stock pot and it turned a darker brown color. The solution in the stock pot is a dark green to begin with. It didn't turn purple or black so I don't know if there's any gold in solution but I'm going to keep the bubbler going for a while longer just to be sure. I'm not sure what is in all of these old solutions so I don't know what the dark brown might mean. That bucket has been going for a few weeks now and I'm starting a new stock pot with all the old solutions that are in the beakers. I've been slowly filtering all of that and saving the filters for later. I'll see what that looks like in a few weeks or so.

I can't believe all the stuff I had sitting there for all those years that I can't even remember what most of it even is. I know I have a good amount of black powder in a little sulfuric acid in one beaker from my reverse electrolysis cell I was running back then. I have quite a bit more plated stuff to run in that again so at least I know what that is!

Thanks again for all the help. I'm enjoying getting back into this again.

If you want to post a picture of your stannous test I would bet that we can tell what metals you have.

It's easy to loose track of what the waste solutions are from.
I do a lot of refining so I produce a fair amount of waste but I always write on each container( with a black sharpie) exactly what type of refining it came from so I know exactly how to quickly deal with the waste without having to do a smell test .

With my gold and silver refines I always loose some powders during the wash process, and this helps keep track of which pm's that I am going to recover at the end of the week from that waste container.

My first step with my waste solutions is vacuum filtering and I recover enough gold, silver, or pgm's from just the filtering alone to make dealing with the waste feel rewarding..
Next step is cementing with copper and depending on what the waste is from I recover a little bit more and often platinum or palladium.

 

[steveonmars]

If you want to post a picture of your stannous test I would bet that we can tell what metals you have.

It's easy to loose track of what the waste solutions are from.
I do a lot of refining so I produce a fair amount of waste but I always write on each container( with a black sharpie) exactly what type of refining it came from so I know exactly how to quickly deal with the waste without having to do a smell test .

With my gold and silver refines I always loose some powders during the wash process, and this helps keep track of which pm's that I am going to recover at the end of the week from that waste container.

My first step with my waste solutions is vacuum filtering and I recover enough gold, silver, or pgm's from just the filtering alone to make dealing with the waste feel rewarding..
Next step is cementing with copper and depending on what the waste is from I recover a little bit more and often platinum or palladium.

I'm filtering everything and setting up a couple stock pots, ones been going for a few weeks. I opened another bucket today and found it was half full of boards in AP, I'm cleaning those and filtering that now. Hopefully it has foils in it when I get to the bottom. That one does test negative for any dissolved metals. Very light color so it might just be mostly water from rinsing the boards off before I put it in storage.

I think I need to denox everything just to be safe, I don't remember what, if anything, has nitric in it. I know that can affect my stannous tests if I remember right. I'm trying to find some sulfamic acid locally so I don't have to order it. I'm going to the big orange box store later but nobody seems to have it in stock. One store I'm going to try today says limited stock so they might have it.

After I denox everything I'll do more stannous tests and try to post them.

 

[Martijn]

A brown stannous test result indicates copper in solution.
The brown solution itself is probably copper chloride.

I think I need to denox everything just to be safe, I don't remember what, if anything, has nitric in it. I

Heat a small amount to 8o degrees C and put a copper wire in it. If any nitric is left, you will see bubbles. No need to denox if there is no nitric.
A little free nitric won't harm the stockpot, it will only consume some copper.

 

[Martijn]

A brown stannous test result indicates copper in solution.
The brown solution itself is probably copper chloride.

I just tested my one stock pot and it turned a darker brown color.

If the spot is too dark to see any purple, dilute a drop of solution with a couple drops of water and draw that diluted solution in a paper tip or swab, then add a drop of stannous. If still too dark, repeat steps and test until you can distinguish brown (copper) from purple (gold). They both can be present but a paper tip can show this a bit better imo due to the capillary effect of paper.

 

[steveonmars]

A brown stannous test result indicates copper in solution.
The brown solution itself is probably copper chloride.
If the spot is too dark to see any purple, dilute a drop of solution with a couple drops of water and draw that diluted solution in a paper tip or swab, then add a drop of stannous. If still too dark, repeat steps and test until you can distinguish brown (copper) from purple (gold). They both can be present but a paper tip can show this a bit better imo due to the capillary effect of paper.

Thanks, that make sense. I think most of those old solutions are probably AR from when I first started this and didn't separate the different boards like I know how to now. I'll try diluting it and see what happens.

 

[Martijn]

don't dilute the whole solution!!! just one drop! you don't need anymore waste water, right?