regarding cyanide leaching?

[gaurav_347]

Dear Members,

How would you go about leaching surface gold from the pcb's for batches of lets say 200 kgs in an industrial environment (My company was thinking of a few tanks with a overhead crane with an attached tumbler which will have the pcbs in them) I have read a few post from GSP but i still have a few questions which i hope it will be cleared through your comments .

Thank you

 

[nickvc]

Which ever method you choose you have to allow the solution to reach and strip all the visible gold followed by a couple of rinse cycles to remove the cyanide.
This method will only remove the visible gold so any encapsulated values will remain unaffected, the same applies to any covered gold or any that was not exposed to the solution.
You may do better stripping the pcbs down, removing pins and any obvious plated items and cutting the fingers off and only processing those, from your 200 kilos you may have only 5 kilos to process, the bonus been less rubbish to foul your solutions, less hazardous chemicals around and smaller volumes of waste to handle.

 

[gaurav_347]

thank you for the reply i think that makes more sense . But when you are going to process about 1 ton per day then how would you go about it? separating the pins or the plated pcb will take a long time.

 

[Lou]

You grind up that ton, separate the magnetics, mill sample assay and accumulate until you go to the copper refiner.


Lou

 

[gaurav_347]

we do have a depopulation process in place where can process 200-300kgs of boards in about 45-60 mins. It depopulates the boards completely. So i guess we just to separate the parts which are plated and which aren't . Thanks Nick.

 

[gaurav_347]

Dear lou,

We have been on that road before . It didnt work out . There are no refineries in my country who would accept such metals and sending it abroad had it's cons!

 

[kjavanb123]

Gaurav,

I have also experienced this path and this what I did,

Cyanide leach using the similar set up,
Grind then pulverize boards
Magnetics removal
Shaker table to separate plastic and metallics
Melt the metallics into copper anode.

Best regards
Kevin

 

[gaurav_347]

Dear Kevin,

I think this makes more sense. My idea was to process the pcb in leaching tanks then proceed to depopulation then classify the components for processing . The blank pcb goes for processing to remove copper from epoxy through mechanical process.