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Refining question


#1

After being in my studio for 25 years I have just finished
remodeling no crack walls or falling down ceilings to worry about any
more.

Which brings me to my question. I have taken all my floor sweeps and
polishing machine dust that has been adding up over the years and
put them into a crucible and burn it out in a kiln to the point that
I have a very fine dust. I know there is gold in there as I have test
samples of it with a torch and flux. But what can I do next to get
gold out.

I did my bench sweeps in the same manner and then heat them up in
the furnace at a friends foundry and poured off the gold but there is
alot of ash still sitting on the top after a full day burning it out.
(which you can still see the gold in) So what to do with the fine
dust? I have read about adding lead but not sure how much to use or
what I am looking for.

Any help would be appreciated.

Thank you
Lauren

I am doing this to learn as I have nothing to lose as I will be
sending the end results to the refinery in the end as I do not want
to play with the acids to do the final step of separating the silver
from the gold.


#2
So what to do with the fine dust? I have read about adding lead but
not sure how much to use or what I am looking for. 

If you never done refining before and not will be doing it in the
future, may be the best is to let refiner handle it. It will not pay
to do setup for one time use. It also requires knowledge in handling
dangerous chemicals.

If you still want to go ahead, you have to get yourself a book on
the subject, because there are details to the process which has to be
studied carefully before beginning.

In broad overview, one smelts dust with fine silver in proportion 1
part of dust to 3 parts of silver; then result is treated with hot
nitric acid (good ventilation is a must); then hot sulphuric acid on
the chance that lead is present; then aqua regia to dissolve all
remaining gold.

Then metals have to be precipitated from solutions and precipitates
are smelted.

Silver is precipitated by table salt (my preference) giving silver
chlorate, to smelt which requires good ventilation.

Gold is precipitated by zinc (my preference as well). Gold forms
brown platelets which is pure metal and smelting does not present any
problems.

That is it in a nutshell. There are many intermediary steps of
filtering and washing and testing to see if everything is going
right, and if there are any other metals present. So good book is a
must.

Leonid Surpin
studioarete.com


#3

You feel comfortable melting lead but not working with acids? I do
something called inquartation and parting which involves nitric acid,
then further refining with aqua regia, but if you’re not comfortable
with acid, I’d suggest you not mess around with this. It can be
extremely dangerous, and if you don’t have the proper tools and
safety equipment can blind and/or kill you.

This is a basic overview:
http://www.ganoksin.com/borisat/nenam/wgc-refining.htm but I think
you’d be better off sending everything to a refinery.

There are a whole mess o’ YouTube videos on the subject as well.

Paf Dvorak


#4

I would suggest spnding a little money and let a quality refiner
refine you sweeps. They have the ability to do it quickly and with a
lot less waste.

They can also handle the toxins that can come from burning down
metals. It will be worth while! Try NTR Metals.

Steve Cowan Arista Designs LLC