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arthur kierski

Well-known member
Joined
Feb 10, 2008
Messages
1,119
Location
são paulo---brazil
i have 20kilos of metallic powder scrap containing 2kilos of ag,90gram of pd and 60grams of au.
this metallic powder contains also lead,tin,very little copper,iron,nickel and perhaps some other base metals------this powder was generated from scraping with a heat gun cellphone boards(300 kilos)------how should i act to recover the pms from these 20kilos ofmetallic scrap?
thanks for any help and sugestions------the other components of the boards like, chips ,gold containing components, was already separated(manually) from these 20 kilos of metallic scrap and dealt with,
thanks again
Arthur

note : i deal with at least 300kilos of cellphone boards monthly---and this 2okilos of mettallic scrap,tends to acumulate
 
Since it’s in powder form or somewhat finely divided I would probably try a wash in hcl to remove what I could of the base metals like tin, nickel, lead. This should leave you with a fairly clean product that should dissolve fairly easily. The only other thing I see is copper which you could remove with the ap process if their is a great quantity mixed in. Once it’s cleaned up you know how to handle it from there. Even though there is a high percentage of silver it should all be divided enough that the silver shouldn’t interfere to much. Try a test sample and see what you come up with
 
goldenchild said:
HCL digestion. Incinerate. Nitric digestion. Incinerate. AR.
Click to expand...
This one could be tricky. It may require a second digest in HCl after incineration, prior to dissolution in AR. I'd likely do a small sample lot before committing to a process that may yield problems in filtration.

Harold
 
Arthur I assume it's not all metallic so the one solution may be to incinerate to reduce the volume, if that's possible, then at least you would have a reduced volume and so need of less acids and a far easier filtration if that's the method you choose. I'd be tempted to look at adding the ashes to copper scrap and set up a copper cell to recover the values from the slimes especially as this seems to be an ongoing problem from your recoveries. The initial cost would be mainly the copper and the rectifier but once up and running it would be relatively cheap and need little attention, the one point to remember is that to get the cell to work properly you need high grade material in, I'd say at least 98% copper. The slimes would still be a mix of metals but would be concentrated making recovery more economic and similar to a stock pot recovery.
 
dear Nickvc, it is all metallic powder-----and making a copper 98% anode would require a lot of copper and that is inviable----the way sugested to me is to pulverise(atomize) these metallics to make it possible a first hcl leach(to eliminate mainly tin and some other base metals)-----

regards
Arthur
 
arthur kierski said:
thanks Harold, i thought cyanide leach would dissolve palladium
regards,
Arthur
Click to expand...
I am under the impression that it does not. I'f I'm wrong, please, somone, correct me.

Harold
 
I believe HCL will dissolve Pd in a finely divided state so... the first and or second HCL digestion will dissolve everything leaving the silver and gold behind. You can then drop out the Pd with copper. The gold and silver are then processed as usual. At least I think this will work if HCL indeed will dissolve Pd.

Mixing the powder very well to get a nice homogenous mix and taking a few, say half pound samples, is a great idea as suggested by Harold.
 
arthur kierski said:
this metallic powder contains also lead,tin,very little copper,iron,nickel and perhaps some other base metals
Click to expand...

I assume Tin and Lead compose the majority of the weight in your powder.

arthur kierski said:
note : i deal with at least 300kilos of cellphone boards monthly---and this 2okilos of mettallic scrap,tends to acumulate
Click to expand...

With that said, i'm puzzled why won't you explore the possibilities of scorification and cupeling.
 
yes Samuel,most of the metal powder is lead and tin.
i never did cupeling and or scorification----i do know the cupeling method for small quantities and for assaying----never thought of doing with 20kilos----
if you could pass an idea of how you would deal with my problem,i would be very glad and thankfull- any way i am going to look for further information on these methods to see if its viable for me----thanks and regards
Arthur
 
arthur kierski said:
yes Samuel,most of the metal powder is lead and tin.
i never did cupeling and or scorification----i do know the cupeling method for small quantities and for assaying----never thought of doing with 20kilos----
if you could pass an idea of how you would deal with my problem,i would be very glad and thankfull- any way i am going to look for further information on these methods to see if its viable for me----thanks and regards
Arthur
Click to expand...


Hi Arthur

I can't say that i have much practical expirience with this subject.
Maybe some of our more expirienced smelters folks can chime in.

Basically, as i understand it from literature and some small scale experimenting i've done, scorification is a process where you make sure all metals are fused in excess of molten Lead inside a reducing atmosphere (low O2 presence), then switching to oxidizing atmosphere to a point where most (but not all) of the lead is oxidzed to litharge, the molten litharge will absorb base metals oxsides where PM's will stay fused with the remaining molten Lead.

It is then poured to a cone mold, slag and button are seperated.
Button is moved to cupeling.
Slag is re-melted and reduced back to metals for assay until you get it right.
 
4metals posted this for large cupelations. A reusable refractory cement box packed with bone ash.

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=49&t=6419&p=56676&hilit=bone+ash#p56676


Do you have a large gas furnace?
 
The old Parkes (Google) process added zinc to the molten lead to separate the silver from the lead, by skimming. I think they then cupelled the skimmings, which still contained some lead.

The Bureau of Mines once published about a 20 page Report of Investigations (RI #????) in which they removed gold, silver, and copper from molten lead/tin solder that had been used in wave soldering operations in the electronic industry. They added aluminum to the melt and the Al alloyed with the Au/Ag/Cu and floated on top of the melt. This was then skimmed off. This both purified the solder and collected the PMs. I don't remember the amount or the form of the Al used, how they added it (and stirred it), or the process they used to separate the Al from the Au/Ag/Cu. These reports are hard to find.
 
Hi Arthur,

There exist patents about "large-scale-cupellation", where the materials to be treated are added to a flux, together with metallic lead, and smelted in a conically formed crucible. Into the liquid mixture air (sometimes even elemental oxygen) is introduced at the bottom by means of steel lancets. Lead and other base metals are oxidized quantitatively, and the litharge formed holds the molten mixture in form of a more or less thin liquid. After having stopped gas-introduction, the precious metals, being heavier than the flux, sink to the bottom of the conical form and are collected there. To me your metal mix seems nearly ideally suited to such a treatment.

Palladium, even in a finely divided form (Pd-black), will not dissolve in HCl, but it can be dissolved quite easily in KCN-solution by slow oxidation with hydrogen peroxide, resulting in a practically colourless solution of K2Pd(CN)4, a very stable complex salt, which is not easily destroyed, even with strong mineral acids. As far as I know, the former Degussa company, has disclosed some patent-applications concerning a leaching process for used automotive catalysts, using cyanide solutions, the Pt being finally dissolved as K2Pt(CN)4.

freechemist
 
thanks freechemist, i am reading all sugestions and will try to do the ones which i am better prepared with my equipments------ if i get good results i will disclose to the forum members that have the same problem-----
thanks and regards
Arthur
 
Another good thread hidden in the depths of GRF.

Arthur, what did you do with the solder in the end? Did you get any results?

Göran
 

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