Clarity needed on Hoke's concept

[grinder]

Folks, I was reading Hoke's book (thanks to frugal refiner) on refining and was trying to relate it with what i was trying to do

I've not started yet and intent to start with a small batch, i have a pound of gold pins, ram fingers, microchips and some other ewaste

i read in hoke's that any gold filled/plated items can be put into nitric acid and water (4:1) to get the base metals dissolved and get working quality gold.
Confusion 1 - Now, if thats the case, why do we have to get the gold fingers treated with HCL/ H2O2 to get the foils out? why can we not use HNO3 directly to get foils?
Confusion 2 - Can we use nitric directly for fiber processor chips? will nitric be able to reach out to the base metals? what about connector pins, lan pins etc

need inputs from frequent refiners, chemists. trollers welcome but keep it humorous )

 

[mls26cwru]

its good that you are reading Hokes.... and your questions are valid... they have also been discussed many times and are already answered on the forum. Search around and you will be enlightened

the reason for using copper II chloride for fingers is a simple one. Hydrochloric acid and hydrogen peroxide are much easier and cheaper to buy. Nitric, for most people, is much more expensive and tough/impossible to buy. $6 for a gallon vs. $120ish... and copper II chloride is safer to handle.

the other question, you will have to search around for, but I believe 'Korvar' would be a good thing to look up to start you on your way.

 

[nickvc]

As mis26 cwru has hinted at there are good reasons things are done in the manner they are.
Hoke was written for jewellers back in 1930s and the metals they were working with were in many ways easier but as you read the whole book strange metals appear and things get a little more complicated to put it politely.
Many of the base metals in e scrap can cause major problems in the recovery processes and mixing different types of scrap is almost a gaurentee for headaches and frustration.
Keep reading and studying and you will find out exactly what both of us are trying to tell you.

 

[kernels]

Also worth knowing that nitric acid and tin cause a sludge called metastannic acid, if your fibre processors have solder on them, this would be worth remembering.

 

[Wingedcloud]

Hello,

To your question about nitric acid and fiber pins: DON'T ever process these pins in nitric acid. You'll regret doing this. It creates a huge mess (metastannic acid from tin) hard to deal with. I talk from personal experience.

Winged

 

[Justincase]

Hello,

To your question about nitric acid and fiber pins: DON'T ever process these pins in nitric acid. You'll regret doing this. It creates a huge mess (metastannic acid from tin) hard to deal with. I talk from personal experience.

Winged

I would say do not process pins by destructive digestion as it leaves the particles of Au very fine and hard to catch or handle if they are less than 2to3p.p.t.
Anything higher can be treated as gold filled.
Meta-stannic acid is Not that hard to handle in it's self, I find a bit of sulphuric acid helps a lot.

 

[glorycloud]

There are reasons why certain tools are used for certain jobs.
Why use a hammer to get a screw into a piece of wood when
a screw driver would be a better choice?

It is the same with the recovery and refining of gold and other PM's from
the e-scrap that you have. Keep reading and studying and you will find
this to be a most enlightening place! 8)

 

[upcyclist]

And that's just the discussion on why AP/copper leach is more efficient (cheaper) to use than nitric for plated materials. Some plated materials also work well with a deplating cell. Since the plating is a relatively tiny amount by weight, dissolving the basemetal involves digesting 99% or more of the metal. At least gold fill material is 1/10th or 1/20th by weight.

slight correction to mls26cwru: it's Kovar, not Korvar

 

[mls26cwru]

slight correction to mls26cwru: it's Kovar, not Korvar

thank you for catching the typo... i must have had Swedish sausage on the brain...

 

[upcyclist]

slight correction to mls26cwru: it's Kovar, not Korvar

thank you for catching the typo... i must have had Swedish sausage on the brain...

That's fine--we have many international types, so I was pointing it out more for the benefit of new readers than anything else.

I was also going to make some sort of anti-Swede joke, since I'm half Norwegian, but decided against it