Removing copper and iron from gold
Mark Wooding
I have a hollow, 9ct, white gold chain formed around a soft iron core.
In an attempt to dissolve the iron core using a 30% solution of
sulphuric acid, the gold became coated in what appears to be a very thin
layer of copper. It seems that the acid had become contaminated during
some of my earlier experiments.
I have two problems now:
1. How to remove the copper; abrasion is not an option here.
2. How to remove the iron core. I suspect that if I can get rid of
the copper and use some clean acid, this should be OK.
Thanks for your time.
--
[mdw]
`When our backs are against the wall, we shall turn and fight.'
-- John Major
Bruce Holmgrain
>I have a hollow, 9ct, white gold chain formed around a soft iron core.
>In an attempt to dissolve the iron core using a 30% solution of
>sulphuric acid, the gold became coated in what appears to be a very thin
>layer of copper. It seems that the acid had become contaminated during
>some of my earlier experiments.
This really is an odd chain.
The copper is a result of electrolytic action between the acid and the two
metals. It usually happens when iron is introduced to a pickling solution.
The iron can be removed in muriatic acid at room temperature. Let it soak for
a day or two. You might want to check it from time to time to make sure that
the acid is attacking the iron and not the gold. I had an odd occaision a
number of years ago where I let a bangle bracelet soak too long (I think that
it was actually a coule of monthes) and alloy was being dissolved leaving a
very spongy form of gold.
The copper can be removed with nitric acid. Make
sure that you clean the muriatic acid out completely before using the nitric
acid. The two combine to form aqua regia which will attack gold. Do be sure to
clean it well before trying this. Sometimes the copper plating will wash off.
Bill Seeley
Mark Wooding wrote:
>
> I have a hollow, 9ct, white gold chain formed around a soft iron core.
> In an attempt to dissolve the iron core using a 30% solution of
> sulphuric acid, the gold became coated in what appears to be a very thin
> layer of copper. It seems that the acid had become contaminated during
> some of my earlier experiments.
>
>
> 1. How to remove the copper; abrasion is not an option here.
The copper oxide can be removed with a vary simple formula.
Hydrogen peroxide pickle can be made with 3% Hydrogen peroxide from
the drug store and a little Sparex or sulphuric acid. Warm the
solution by filling one bowl with hot water then place another bowl
in the hot water. Add a little of the acid component to start the
reaction. The acid is a catalyst so more will not do much. Some
smut may form on the surface but it will come off with regular
pickle. Bill
Mark Wooding
Bruce Holmgrain <manmount...@KNIGHT-HUB.COM> wrote:
>
> >I have a hollow, 9ct, white gold chain formed around a soft iron core.
> >In an attempt to dissolve the iron core using a 30% solution of
> >sulphuric acid, the gold became coated in what appears to be a very thin
> >layer of copper. It seems that the acid had become contaminated during
> >some of my earlier experiments.
>
Well, it's actually a tube of gold; the iron core is there to stop the
tube from collapsing when it's bent.
> The copper is a result of electrolytic action between the acid
> and the two metals. It usually happens when iron is introduced to a
> pickling solution.
Righty.
> The iron can be removed in muriatic acid at room
> temperature. Let it soak for a day or two. You might want to check it
> from time to time to make sure that the acid is attacking the iron and
> not the gold. I had an odd occaision a number of years ago where I let
> a bangle bracelet soak too long (I think that it was actually a coule
> of monthes) and alloy was being dissolved leaving a very spongy form
> of gold.
I've not come across the term `muriatic' before, nor can I find it
mentioned in any reference books in my possession. Could you (anyone)
enlighten me, please?
I'll be careful about leaving the gold in too long. ;-)
> The copper can be removed with nitric acid. Make sure that you
> clean the muriatic acid out completely before using the nitric
> acid. The two combine to form aqua regia which will attack gold.
OK.
Bruce Holmgrain
>
> I've not come across the term `muriatic' before, nor can I find it
> mentioned in any reference books in my possession. Could you (anyone)
> enlighten me, please?
Muriatic acid is the form of hydrochloric acid thqat you can find at any
hardware store.
Bruce Holmgrain
E-mail: manmount...@knight-hub.com
HTTP://www.knight-hub.com/manmtndense/bhh3.htm
Snail Mail: POB 7972, McLean, VA 22206
Nicholas Hawthorn
This reply is just barely on topic. Could someone satisfy my
curiosity as to what metals are alloyed with gold in white gold
and 22 carat gold? This is also relevant to how these react
with acids.
Nick Hawthorn
n...@mhri.edu.au
Bruce Holmgrain
>This reply is just barely on topic. Could someone satisfy my
>curiosity as to what metals are alloyed with gold in white gold
>and 22 carat gold? This is also relevant to how these react
>with acids.
The major coloring agents for white gold that I am familiar with
are nickel or palladium. Neither of these pose any appreciable
difference when trying to disolve iron or copper in the vicinity
of.
******************************************************
Bruce D. Holmgrain
E-mail: Manmount...@Knight-Hub.com
WWW: http://www.knight-hub.com/manmtndense/bhh3.htm
Snail Mail: POB 7972, McLean, VA 22106
Mark Wooding
Nicholas Hawthorn <n...@cortex.mhri.edu.au> wrote:
> This reply is just barely on topic. Could someone satisfy my
> curiosity as to what metals are alloyed with gold in white gold
> and 22 carat gold? This is also relevant to how these react
> with acids.
These aren't actually set in stone; different formulations have
different machanical properties (e.g., hardness, melting point, etc.).
The compositions here are typical, apparently:
22ct (always yellow) gold is
91.67% gold
5% silver
2% copper
1.33% zinc
White golds come in various carats:
18ct: 75% gold, 25% platinum or paladium
75% gold, 10% paladium, 10% nickel, 5% zinc
(this one has a lower melting point, and could be used
as a solder)
14ct: 58.33% gold, 23.5% copper, 12.2% nickel, 5.97% zinc
10ct: 41.67% gold, 32.8% copper, 17.1% nickel, 8.4% zinc
(Data from /Jewelry Concepts and Technology/ by Oppi Untracht.)
Abrasha
Bill Seeley wrote:
>
> Mark Wooding wrote:
> >
> > I have a hollow, 9ct, white gold chain formed around a soft iron core.
> > In an attempt to dissolve the iron core using a 30% solution of
> > sulphuric acid, the gold became coated in what appears to be a very thin
> > layer of copper. It seems that the acid had become contaminated during
> > some of my earlier experiments.
> >
> >
> > 1. How to remove the copper; abrasion is not an option here.
Remove the iron by boiling the bracelet in a water and ALUM solution. I use this method
to remove broken drill bits from gold. Work very well, just takes a while. I assume
removing the iron core from a bracelet will work quite a bit longer.
Iron can also be removed from cores of gold alloys electrochemically. I do not know
exactly how, but this method is very fast.
Abrasha
http://www.abrasha.com
C++ Freak
I made 22 carat gold by just alloying pure gold with 4% copper and
4% silver.
It is soft when annealed, but *hard* when worked.
It can be worked virtually limitless without annealing.
Klaas
C++ Freak
When it is only nine carat AND there is no platinum in it,
you can dissolve it in nitric acid (~50 % HNO3)
and this dissolves *all* metals (including palladium) except the gold.
The brownish residue can be filtered out and that's the gold with a
high content (> 95 %).
Any gold alloy with less than 50 *atom* percent of gold and no Pt or Ir in it
can be treated that way to reclaim the gold.
When the atom percent is more then 50 (from 10 ct on)
one can melt the alloy and 'dilute' it with some copper.
Let it freeze and roll it into thin sheet to make as much surface
as possible. When you have no rolling mill, just use a sledgehammer.
Don't worry of annealing or cracks, as the metal is to be dissolved and
is not an 'end-product'.
Then dissolve into nitric acid.
Klaas