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Recovery of Metal from PCP

01/09/2010 3:36 PM

Is there any economical way of selectively dissolving the non metallic components of a PCB(Printed Circuit Board) so that all the metal values can be recovered(gold,copper etc.)?

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#1

Re: Recovery of Metal from PCP

01/09/2010 11:36 PM

Turn it around. Desolve the metals and then recover them.

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#2

Re: Recovery of Metal from PCP

01/10/2010 12:25 AM

The correct way to do this is to grind up the PCBs, and then dissolve out the metals with aqua regia (3 parts concentrated hydrochloric acid to 1 part concentrated nitric acid). The solution is then purified, first by filtration, and then by a ligand. Finally, cyanide is used to separate the gold from the other metals in solution.

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#3

Re: Recovery of Metal from PCP

01/10/2010 3:53 AM

Hi,

the economic way is to build a melting oven that can be heated to 1100°C and that accepts near 100 to 1000Kg.

Load it with 80% copper and 20% PCBs.

Organics will burn away - so you will need a powerful control of exhausted toxics.

Glass will melt and prevent the metals from oxidation.

Metals will dissolve in molten copper, cast and reprocessed in copper (galvanic) refinery.

There will also the precious metals and nickel be extracted from the anode slug.

If you think about small scale: no generally accepted way existing. Aqua -regia is more costly than the materials worth you will get and dangers of poisoning yourself and others will stop anybody soon.

Small scale gold and copper extraction is possible by boiling in an chloride-nitrate solution.

Search the SciAm archives for the way the INCA-Indians used.

RHABE

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#4
In reply to #3

Re: Recovery of Metal from PCP

01/10/2010 9:02 AM

A few of these furnaces are still in use in the Cero Rico vicinty of Bolivia. If one can acclimatize to the Alto Plano elevation (chewing coca helps as does drinking the tea) the people would be happy to show how it's done. Chemical plating is also done there.

One word of caution.......contrary to what the Bolivians believe the coca tea is not allowed to be imported.

Best of the New Year Rhabe

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#6
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Re: Recovery of Metal from PCP

01/10/2010 10:50 AM

Thank you, same to you!

If you have any information about these "lost" technologies, please give a link or description.

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#7
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Re: Recovery of Metal from PCP

01/10/2010 11:07 AM

I'll see if I can retrieve the photos from old hd.

I was there 15 years ago and saw them. There are places where gold miners bring their 'rough' to get smelted. Saw lots of arsenopyrite and arsenic. Copper also. Unfortunately couldn't stay long because of elevation and outbreak of typhus.

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#8
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Re: Recovery of Metal from PCP

01/10/2010 11:48 AM

This seems to be first roasting to remove sulfur as SO2,

and then reducing (with charcoal) to metal.

Problem is the high sulfur and the high arsenic both pretty poisonous if as fumes.

Would be very interesting too!

We had (250 to 300 years ago) a nearby copper smelting activity where blond people were reported to have green hair. So permanent low level copperseems to be survivable but arsenic and sulfur caused a very low life expectancy.

The INCAs used something different - boiling solutions of ? nitrates and chlorides from Atacama desert to bring into solution the metal and boil in another solution to plate gold on copper.

I had typhus as 5 year old - barely survived, very bad.

Elevation: never exceeded 4000m, likely not possible today.

The best to you

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#10
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Re: Recovery of Metal from PCP

01/10/2010 2:43 PM

I've read about the green blondes. Not good.

After two weeks being above 3000m I'm not sure what I was seeing or thinking. Oxygen depravation has some interesting effects.

I do remember many small mud and stone type furnaces. Many collapsed. Lots of green copper sulfate staining the ground. I think they were extracting gold from the arsenopyrite.

To this day I cannot understand how it is possible to survive in those altitudes......but .....there was a people there capable of building a remarkable civilization for themselves. I've read they could chemically combine nickel to copper (Chinese did that with steel). Interesting is that there's lots or iron type ores but no evidence of their ever having smelted or used it.

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#11
In reply to #10

Re: Recovery of Metal from PCP

01/10/2010 2:59 PM

Iron smelting: may be not possible with this low oxygen.

At near sea altitude a strong natural wind and some concentration is necessary. We tried (300m alt) a blower but resulted only to produce a lot of Fayalite.

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#12
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Re: Recovery of Metal from PCP

01/10/2010 4:26 PM

True about the altitude......but all through southern and central America I have not heard or read of iron being produced with the exception of some iron meteorites in the arctic regions that were made into tools. Copper was mined by the native nations as far as the Arctic but no evidence of the tools has yet to be found (except for a 2500 yr old copper knife that was made in China and found in Ontario...which I have my doubts about its origin. I think it was made by the Ojiway nation). More pausible was a Viking sword discovered in Ohio.

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#5

Re: Recovery of Metal from PCP

01/10/2010 9:40 AM

If the base polymer of PCB IS KNOWN A SOLVENT CAN BE SUGGESTED.

You can try Heating

Chilling is also an option in which the metal part can shrink down and fall out on hammering.

You can also dry Micro wave oven.

One more option is to chip down or crack down the PCB Board being brittle, fuse it in a furnace. The metal will settle at bottom and plastic will float at top.Now you can chip out the plastic, further surface grind and get the pure metal part.

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#9

Re: Recovery of Metal from PCP

01/10/2010 12:42 PM

Cheapest method may be anodic dissolution of the metals. This will leave the plastic intact which may have some use.

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#13

Re: Recovery of Metal from PCP

01/10/2010 5:26 PM

Greetings to all in 2010..

All approaches have merit..I'd like to suggest another approach...Place the part(s) in a slurry of sand/water(or other suitable media) filled container of appropriate size..Grind it using a mortar pestal approach...Put the residue into a a large enough centrifuge(there's a company in Waterloo region that makes them to order if you have sufficient capital) and spin a suitable aliquot of this ground sample....collecting the seperated layers..Analyze the contents and then grind again perhaps using quartz sand or even clay or metal filings as the abrasive..Eventually a relative purity of different materials will be achieved..In my minds eye you could,again if you have sufficient capital to pay for the centrifuge...power consumption..etc..have a fairly decent seperation based on mass/gravity differences..Whether or not this would yield pure elements i really don't know...if the goal is to make money bigger would be better...Whatever... it would be fun to try...

Regards,Marty Wolf

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