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Hydrofluoric acid/quartz etching


#1

Greetings All,
Does anyone know of a good source for hydrofluoric acid. I am
having trouble locating some.

I am also looking for tips/advice for etching quartz away to
expose the gold contained within.

I know this is dangerous stuff to work with, but any advice will
be appreciated.

Thanks

Mike Shell
Minerals and More
P.O. Box 371,
Bethel, Ohio 45106

@Mike_Shell


#2

Mike,

One problem/danger thst is if often overlooked when HF is used
for quartz removal is that the quartz mostly ends up in the form
of a very, very toxic gas. Not only is there the short term
toxicity, but long term the effect on the lungs is very serious.

HF liquid is a “weak” acid as far as the effects on most metals
is concerned. It is, however, very bad on skin and eyes. Much
more dangerous to skin and tissue than “strong” acids are.

In these days it is more difficult to get chemicals than it once
was. If you know someone at a local college, you should be able
to get a small quantity from there. Chemical supply houses do not
sell to anyone but listed companies. It will be necessay to
establish yourself with them.

Unless the concentration of gold is rather high in the quartz,
it would be difficult to not spend more for the chemicals, labor,
etc. than the qold is worth. The rate of solution is slow without
boiling the liquid and what do you boil it in? All ceramics and
glass are out. In lab sized experiments, it is usually boiled in
a platinum dish which works very well. What quantity of quartz do
you have to treat?

TOM (OWL1)


#3

Hello All,

I want to take this opportunity to thank everyone who responded
to my posting regarding hydrofluoric acid.

After reading all the responses, I have decided not to fool with
the stuff. It simply isn’t worth the risks.

Again, thank you all for your input!

Regards,
Mike Shell
Minerals and More
P.O. Box 371,
Bethel, Ohio 45106


#4

On 04-Jan-97, Mike Shell wrote aboutRe: hydrofluoric acid/quartz etching:

MS> I am also looking for tips/advice for etching quartz away to
MS> expose the gold contained within.

G’day Mike; I don’t think that it is necessary for you to use HF
get at the gold in quartz. Modern practice is to crush the
quartz finely, then put it into a continuously stirred vessel
(not metal) with a dilute solution of potassium or (cheaper)
sodium cyanide through which air is bubbled. I used a solution
of about 1 percent cyanide in a plastic basin and an aquarium
aerator with a diffusing stone as sold in all aquarium shops. Do
this in your garage, or lean-to shed, and don’t breathe the
aerosol which comes from the aerated cyanide. A few days later I
applied a few volts DC from a small battery across the solution,
using stainless steel electrodes (I used scrap from an old
saucepan) You’ll get a thin film of gold on the negative
electrode which peels off fairly easily. The same process is
used with silver, which my wife used regularly to reclaim silver
from waste solutions in a teaching laboratory. She precipitated
the silver as chloride, washed and filtered it, dissolved it in
cyanide, then plated it on to a stainless electrode. She peeled
off the pure silver, dissolved it in nitric acid and crystallised
it as Silver Nitrate ready for re-use in the lab. This was done
when William Bunker Hunt tried to get a corner on silver some
years ago, and the price of lab reagent silver nitrate was
around $1.00 per gram - and the lab used over 1000 grams a year!
Doubtful about the process? Then get a book from the library on
gold mining and refining techniques. /\ / / John Burgess, / / /
//\ johnb@ts.co.nz / / \ \ / (___) \ (_________)


#5

Years ago, I got hydroflouric acid from a company in Rockville,
Maryland name North-Strong. All other sources wanted me to buy a
55 gallon drum. They didn’t want to stock the stuff. I don’t know
if North-Strong is still in business.

A word of caution.

I was using very small quantities of the stuff. Maybe a half
ounce to an ounce at a time. No gloves. Just a little careless.
got a drop or two on me. I didn’t notice. This stuff doesn’t
attack skin. I passes through it. Underneath the skin it will
bind with calcium. Well, I noticed a burning sensation. By that
time it was too late. I didn’t know that the stuff had passed
through my skin. I tried to wash it off. Tried to neutralize it.
Saw a doctor. The doctor didn’t see anything and just had me soak
it in a whirlpool. I suggested that the bottle recommended some
type of injection under the fingernails. He still acted as if I
was just trying to get off of work or something. A few days
later, my fingernail fell off. Not too great a disaster, but it
was only a drop or two at most.

A couple of monthes ago there was a very good article about
hydroflouric acid poisoning in Discover magazine. I’d tell you
what issue, but a couple of days ago I cleaned house and chucked
everything that wasn’t a permanent fixture. Sorry. Wish I’d saved
that.

E-mail: manmountaindense@knight-hub.com WWW:
http://www.knight-hub.com/manmtndense/bhh3.htm Snail: POB 7972,
McLean, VA 22106


#6

Does anyone know of a good source for hydrofluoric acid. I am
having trouble locating some.

G.F.S. chemical,Dublin,Ohio