Processing Questions

[henn111]

I have ordered all chemicals and equipment needed and already had some to start. Worked around acids all my life so I am familar to all hazards and toxic fumes. With that said, processing questions.
1. I have a boatload of bare/new/rejected gold plated flatpacks and connectors various sizes used in the microwave electronic industry.They are all 50 millionths thick. They are plated over nickel and the base is kovar. If I put these
into AR will the kovar cause me problems in the end when I percipitate the gold using SMB?? If so what is the procedure or please direct me in this forum to the right place??

2. After the reaction is complete using AR and the parts are stripped of gold the next step is to neutrilize the Nitric using urea. Is that correct?? Or if the reaction is dead can I than just add SMB??? Of course after
discarding the parts left and filtering.
Thanks

 

[martyn111]

2. After the reaction is complete using AR and the parts are stripped of gold the next step is to neutrilize the Nitric using urea. Is that correct?? Or if the reaction is dead can I than just add SMB??? Of course after
discarding the parts left and filtering.

If you still have metallic parts that are 'stripped' then you shouldn't discard anything. The values will have cemented onto these metallic parts, as a result you would be discarding your values with the trash.

The advised method would be to remove the base metals first using nitric acid diluted 50 / 50 with distilled water, once everything that will dissolve has done so, then any remaining solids can be dissolved using AR or the solvent of your choosing.
If you have chosen the AR method and everything is now dissolved, neutralise the nitric either by adding urea (not the method of choice on the forum) or evaporating down to syrup and diluting with Hcl at least 3 times until no nox fumes are evolved when adding the Hcl.
Dilute the remaining solution to 3 times its volume with water, filter and drop the gold with the precipitant of your choosing.

 

[henn111]

So I can't just put the whole flatpack in the AR and strip the gold producing gold chloride, pour most of the liq, rinse parts 2-4 times adding to solution, filter, neutrilize, then drop out the gold? I must first strip off the gold from the kovar????

If so wow process galore. I did some of that playing around with ferric chloride and mega hcl and it worked from circuit bds and flat packs but its tedious. God a bagfull of dirty gold flake.

 

[martyn111]

So I can't just put the whole flatpack in the AR and strip the gold producing gold chloride.

Thats correct, the gold will not stay in solution as long as there are other metals present, in a solid form, higher in the reactivity series than gold.

 

[henn111]

Ok thanks time to get stripping with Nitric

Thanks much

 

[jack_burton]

Without a picture it's a little hard to tell, but it almost sounds like you'd be better off stripping the gold in a sulfuric cell. A lot cheaper than nitric and WAY less waste to deal with.

 

[henn111]

Picture of some parts

 

[jack_burton]

Yeah no way I'd want to deal with all that base metal using any form of nitric, myself. I'd process that all via sulfuric cell. But everyone has slightly different ways of doing things.

 

[maynman1751]

Yeah no way I'd want to deal with all that base metal using any form of nitric, myself. I'd process that all via sulfuric cell. But everyone has slightly different ways of doing things.

Right on! Way toooo much steel (base metal)!!!

 

[martyn111]

Now that I have seen pictures of the material you are attempting to process I'm with jack_burton and maynman, forget dissolving that amount of base metals in nitric acid, go with the sulphuric stripping cell.

 

[henn111]

Thanks