Processing waste for PMs

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Rreyes097

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So I processing my waste and that was quite a bit of sludge at the bottom of my copper cementation apparatus. So I figured I should go ahead and process it. So I started with a hot water Rinse. Then an hot HCL boil. I just tested it and found that there may be palladium? Now if that's the case then I don't think I'm ready for palladium but do not want it to go to waste. Do I process this? If so how? I wasn't ready for this. 🤷
 

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Yggdrasil

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Pd is light to emerald green on a stannous test, that looks lite pink to me. What material have you been running.

I might be wrong....but I was thinking that Rh shows on a stannous test as pink.... maybe.
Seem a bit odd for Rh, it barely go into solution with AR so much less in straight HCl, right?
There are several other metals that may report to the Stannous.

Maybe just a dilute Gold reaction?
There may be some residue oxidizer of sorts.
How did you stir your cementing?
 

Rreyes097

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Seem a bit odd for Rh, it barely go into solution with AR so much less in straight HCl, right?
There are several other metals that may report to the Stannous.

Maybe just a dilute Gold reaction?
There may be some residue oxidizer of sorts.
How did you stir your cementing?
Well I ran some hot HCl through it and now stannous is negative. But the sludge is thick and I can't keep trying to dissolve all of it with simple HCl. So I was thinking about going ahead and seeing if aqua regia will dissolve any gold or other precious metals? What say the forum? I'm hesitant to do so because it really is a sludgy mess in there and for me to dissolve it with HCL it would take a lot of hcl. But if I form aqua regia, won't it create even more of a mess?

I'm attempting to stir with my magnetic stirrer but the sludge at the bottom is preventing it from working properly. But that's not what you mean is it? How did I stir or agitate the cementation in my copper cementation apparatus? I used an aquarium air stone at the bottom of a slotted cylindrical tube that connects to the lid. I made one before this one and posted both previously so there are pics of what I'm using. But I'm not sure how to attach portions of past posts of mine. But yeah that's what I used and I let each fill up of waste solution stay in cementation for minimum 48 hrs.
 

Yggdrasil

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Well I ran some hot HCl through it and now stannous is negative. But the sludge is thick and I can't keep trying to dissolve all of it with simple HCl. So I was thinking about going ahead and seeing if aqua regia will dissolve any gold or other precious metals? What say the forum? I'm hesitant to do so because it really is a sludgy mess in there and for me to dissolve it with HCL it would take a lot of hcl. But if I form aqua regia, won't it create even more of a mess?

I'm attempting to stir with my magnetic stirrer but the sludge at the bottom is preventing it from working properly. But that's not what you mean is it? How did I stir or agitate the cementation in my copper cementation apparatus? I used an aquarium air stone at the bottom of a slotted cylindrical tube that connects to the lid. I made one before this one and posted both previously so there are pics of what I'm using. But I'm not sure how to attach portions of past posts of mine. But yeah that's what I used and I let each fill up of waste solution stay in cementation for minimum 48 hrs.
Maybe try some dilute Nitric first.
How much sludge are you talking about?
 

Rreyes097

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Roast it first of course.
Or just roast it and save it for later until you have a sizeable batch
So your saying perhaps dry it so it can be roasted? Or save it for more sizable batch? I kind of feel that this sludge waste is quite a bit already and processing a lot more of it at a time would or could stretch my capabilities ie glassware or lack thereof. Perhaps I'll dry and roast, then dilute nitric as you have advised. But AR is definitely a bad idea straight from just HCl?
 

Yggdrasil

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So your saying perhaps dry it so it can be roasted? Or save it for more sizable batch? I kind of feel that this sludge waste is quite a bit already and processing a lot more of it at a time would or could stretch my capabilities ie glassware or lack thereof. Perhaps I'll dry and roast, then dilute nitric as you have advised. But AR is definitely a bad idea straight from just HCl?
Not neccessarily.
How much was processed in this waste volume?
 

Rreyes097

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Not neccessarily.
How much was processed in this waste volume?
Maybe processed 5 to 7 gallons of waste, which includes all processes related to basic gold recovery such as: AR, nitric acid, HCl, and including all rinses. So probably not much. But the sludge got so thick I was kind of forced to process it or build a bigger cementation apparatus.
 

Yggdrasil

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Maybe processed 5 to 7 gallons of waste, which includes all processes related to basic gold recovery such as: AR, nitric acid, HCl, and including all rinses. So probably not much. But the sludge got so thick I was kind of forced to process it or build a bigger cementation apparatus.
Is this cemented on only Copper?
 
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