IBM ceramic CPUs and their boards

[kjavanb123]

Cyanide is so fast and great for gold plated or even silver scraps.

It certainly is, however how do you check to make sure that you have no values left in the solution before calculating your yields?

I left couple of large aluminum foils in pregnant cyanide solution for over 24 hours and the fact some part of those fails didnt turn grayish black tells me that all gold was cemented by foils.

 

[kjavanb123]

Niks

Yes that seems low since these are old boards and I had recovered 150 ppm Au from such boards using lead smelting.

No I haven't done silver/palladium recovery on them yet or copper.

They are going to be done soon. I am also collecting small socket PC boards for processing

Glad to hear it, still for large socket MB (& slot CPU MB, pre-2001) a number of ~170 PPM Au would be my guess, Ag & Pd yields there should be rather high, so that too needs to be accounted for, for full value; also Cu...

As I understand, lead smelting is your "industrial" way of processing MB, and HCL+AR is analytical, laboratory method? If so, it's a little bit strange that the latter yields lower than former - one would think it should be the other way around, it`s obvious that streamlined industrial process could leave some fringe values behind, analytical process on the other hand should be as precise as possible... Maybe go over your designed procedure once more, where could the losses come from? On a hunch, mechanical processes (like grinding, milling) always make me nervous when it comes to soft, malleable gold......
In any case I am eagerly looking forward your results, as always

Niks

I have had better results smelting with lead oxide specifically on bigger lots (100lbs+).

When using chemicals to recover values from such small sample, room for error and losses is higher.

In my next batch I will use litharge to process SMDs and ICs to make sure I can get majority of values.

I am currently depopulating 3.6 kg of small socket MB, as I am collecting more to reach at least 20 kg lot, trying to remove SMDs and a luminous capacitors manually, since SMDs during my heated depopulation gets mixed with solders.

For my new lot of small socket PCBs I want to recover aluminum as well as solders along the metals of interest.

KJ

 

[niks neims]

I have had better results smelting with lead oxide specifically on bigger lots (100lbs+).

When using chemicals to recover values from such small sample, room for error and losses is higher.

makes sense

For my new lot of small socket PCBs I want to recover aluminum as well as solders along the metals of interest.

good idea & excellent approach, especially since you probably have some use for aluminium in your in-house processes... I would suggest for you to look in to recovering tin (from solder, etc.) also, I have a hunch there is quite a lot of untapped value there (have heard about 2% (no idea if it is even realistic)), with spot price being up to $21/kg, total Sn value in MB could be on par with that of Ag.... especially since most large processors don't pay out on it at all...

Maybe NaOH leach for tin & aluminium? or HCL?

 

[anachronism]

Cyanide is so fast and great for gold plated or even silver scraps.

It certainly is, however how do you check to make sure that you have no values left in the solution before calculating your yields?

I left couple of large aluminum foils in pregnant cyanide solution for over 24 hours and the fact some part of those fails didnt turn grayish black tells me that all gold was cemented by foils.

Cyanide can take a lot longer to drop its goodies than that. Depending upon the type of oxidant, the strength (or over strength) of CN- used it can take many days or weeks.

Edit I hope you kept all your "spent" solutions.

 

[kjavanb123]

[/quote]
good idea & excellent approach, especially since you probably have some use for aluminium in your in-house processes... I would suggest for you to look in to recovering tin (from solder, etc.) also, I have a hunch there is quite a lot of untapped value there (have heard about 2% (no idea if it is even realistic)), with spot price being up to $21/kg, total Sn value in MB could be on par with that of Ag.... especially since most large processors don't pay out on it at all...

Maybe NaOH leach for tin & aluminium? or HCL?
[/quote]

Niks

We use aluminum to drop Pd from nitrate silution as we add HCL to Pd nitrate and aluminum and it does cementing rather quickly, also for silver chloride conversion to silver aluminum scrap is used.

Heat sinks that we save from PC boards are excellent for these. Aluminum foils comes from restaurants take-out.

During my depopulation which is done inside an oven designed for this purpose, solders are recovered as molten pieces and can we separted from the rest of components easily by sifting. But that requires to remove SMDs prior to oven depopulating.

Regards
KJ

 

[kjavanb123]

It certainly is, however how do you check to make sure that you have no values left in the solution before calculating your yields?

I left couple of large aluminum foils in pregnant cyanide solution for over 24 hours and the fact some part of those fails didnt turn grayish black tells me that all gold was cemented by foils.
[/quote]

Cyanide can take a lot longer to drop its goodies than that. Depending upon the type of oxidant, the strength (or over strength) of CN- used it can take many days or weeks.

Edit I hope you kept all your "spent" solutions.
[/quote]

Yes I have kept spent cyanide solution. Whenever I used zinc powder, cementation was completed in 24 hours so in thick telecomm pons actually in an hour.

Is it so because aluminum reaction is differnt from that of zinc powder?

 

[kernels]

Appreciate your sharing kjavanb123! Always nice to see what you are up to.

 

[anachronism]

It's not necessarily completed so fast, and there's the "redissolve" thing that can be going on as well.

 

[nickton]

I often wonder whether some of the gold plating isn't just spray painted on by dishonest manufacturers.