Cemented palladium

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Geo

Well-known member
Joined
Mar 1, 2011
Messages
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Location
Decatur,Ala.
I had enough free time to work on some secondary stuff I have been collecting. I process whole boards, such as ram, video and sound cards, some CPU's, and a few other high end boards in AP to both liberate the foils as well as chips and SMD's. Through a screening process, the chips are removed and anything larger than the smaller tantalum capacitors. Anything smaller goes on to the next process where I dissolve the gold foils from the remaining solids with HCl and bleach. I enjoy pretty good success doing this and it leaves the MLCC's and film resistors virtually intact. The leech is not on the material long enough to dissolve any PGM's and any that it does comes out in the stock pot.

So I rediscovered a container of mixed SMD's that has gone through this process and decided to give Pd another try. Only this time, I wasn't going to try and refine. I was going to make as pure a solution as I could and cement the Pd out using aluminium turnings. I then cleaned the cemented powder with a boiling, dilute HCl bath. I followed this with a boiling Dilute sulfuric acid bath. I followed this with several boiling water rinses. All of this on a hot plate stirrer with good stirring. I dried the powder and roasted it over a camp stove flame. I then melted it using propane/oxy cutting tip in a high back melting dish. I will have it assayed Monday. I think it was a decent result.

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Nice Geo.
You may have lost a little in the Hcl wash but as it was dilute it would be a small amount, be very interesting to see what the assay says.
 
The assay was 69.3% palladium. I'll get the report scanned in and post it tomorrow. It wasn't super easy but it is doable. I am going to start taking SMD's on toll refines. I'm sure I can get the purity up to 90%.
 
Geo said:
The assay was 69.3% palladium. I'll get the report scanned in and post it tomorrow. It wasn't super easy but it is doable. I am going to start taking SMD's on toll refines. I'm sure I can get the purity up to 90%.

Geo,

Definition of SMD Devices from Euro Circuits:
https://www.eurocircuits.com/smd-surface-mount-device/

"SMD – Surface Mount Device. Surface-mount technology (SMT) is a method for producing electronic circuits in which the components are mounted or placed directly onto the surface of printed circuit boards (PCBs). An electronic device so made is called a surface-mount device (SMD)."

Not trying to be a pain, but, which SMD components are you interested in toll refining?

Peace,
James
 
MLCC's and film resistors. Other surface mounted devices may have a small amount of precious metals but not really what I am after. I have video of the material this came from posted on my group. I didn't post it on youtube.
 
I know I don’t have to warn you but be careful when working with PGMs especially if you are working with them regularly.
 
Thank you Nick. Yea, seems I am very popular now. Everyone has been stockpiling then and not knowing what to do with them. As soon as I posted my success, I've been flooded with request for tolls. Definitely going to have to be safety oriented all the time. I understand that it may have contributed to Frank's death as well as Freechemist. Certainly not something to take lightly.
 
If you use Cu powder you will cement the Ni. Al wont cement Ni.

Additionally Al is cheaper and easier to remove from other metals.

Eric
 
Eric is right. It's even cheaper than zinc powder. I bought my aluminum turnings but there is a machine shop close by that I can get them for free. I am just concerned about impurities in the aluminum.
 
If you use Cu powder you will cement the Ni. Al wont cement Ni.

This statement flies in the face of cementation based on the normal electrode potentials as listed in the electromotive series. While it is possible that there are mitigating circumstances to this general rule, I hope you are willing to post some back up to this claim.
 
Yea, I didn't say anything about it. I was agreeing that aluminum is easier to clean up after the drop. A simple HCl bath will remove any left over aluminum. As far as the nickel, it has been my experience that nickel can not be removed from solution through ionic exchange. It can't be cemented from solution. There are other metals that once it is dissolved in an acidic solution, can't be cemented back out. Aluminum is another.
 
Ok, here is an abstract were they are cementing copper on nickel. https://www.tandfonline.com/doi/abs/10.1179/cmq.1971.10.3.165?journalCode=ycmq20
So either way nickel should not cement on copper.
 
Geo said:
Yea, I didn't say anything about it. I was agreeing that aluminum is easier to clean up after the drop. A simple HCl bath will remove any left over aluminum. As far as the nickel, it has been my experience that nickel can not be removed from solution through ionic exchange. It can't be cemented from solution. There are other metals that once it is dissolved in an acidic solution, can't be cemented back out. Aluminum is another.

Your statements are much to broad. Ionic exchange is one of the primary methods by which nickel is recovered from industrial waste. The nickel in solution from refining wastes is cemented just fine by the addition of iron.

What happens is that the aluminum in solution interferes with the cementation of nickel in solution.

https://www.jstage.jst.go.jp/article/nikkashi1972/1982/1/1982_1_44/_article/-char/en
 
Thanks snoman701. I guess there are exceptions to every rule. I just don't happen to be working with sulfates. I just have never cemented nickel on iron or anything else I can think of. DMG will drop nickel from basic solutions.
http://goldrefiningforum.com/~goldrefi/phpBB3/viewtopic.php?f=58&t=9158
 
snoman701 said:
Geo said:
Yea, I didn't say anything about it. I was agreeing that aluminum is easier to clean up after the drop. A simple HCl bath will remove any left over aluminum. As far as the nickel, it has been my experience that nickel can not be removed from solution through ionic exchange. It can't be cemented from solution. There are other metals that once it is dissolved in an acidic solution, can't be cemented back out. Aluminum is another.

Your statements are much to broad. Ionic exchange is one of the primary methods by which nickel is recovered from industrial waste. The nickel in solution from refining wastes is cemented just fine by the addition of iron.

What happens is that the aluminum in solution interferes with the cementation of nickel in solution.

https://www.jstage.jst.go.jp/article/nikkashi1972/1982/1/1982_1_44/_article/-char/en
The article is discussing sulfate solutions and even with aluminium present 40% of the nickel did cement. Now the article were written in Japanese so I don't know a lot of the details about the experiment. For example I couldn't find the nickel concentration of the sulfate solution.

The copper added was added as a salt to the solution (0.2 g/liter) and that made the cementation work perfectly.

This is my impression of how the experiment worked out...

Adding metal iron to a nickel sulfate solution cements nickel while iron goes into solution.
If there is a small contamination of aluminium sulfate it will interfere with the cementation so only 40% of the nickel did cement out until it stopped working (under the same conditions as above).
Adding 0.2g of copper ions per liter of nickel solution lets the cementation of nickel on iron work again.

Nickel does not cement on copper, or every copper refinery would be out of business. The main contamination in copper sulfate electrolyte is nickel sulfate. The first step in electrolyte treatment is nickel sulfate removal by crystallization, showing that it is quite concentrated in the electrolyte without contaminating the electrolytic copper cathodes.

At least that is what I think happens in real life.

Göran
 
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