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chemistrycoach

Well-known member
Joined
Dec 25, 2011
Messages
51
hello merry christmas ! just want to ask what happens to gold powder that comes out during precipitation if we rubbed it on a solid wall or object? will the gold appear? thanks in advance mates !!!
 
i'm trying learn something each day about refining gold please someone might know the answers to my questions i tought gold cannot oxide
1) what is gold oxide?
2) can gold oxide be chemicaly treated to get its form back to gold as in Au ?
 
chemistrycoach said:
i'm trying learn something each day about refining gold please someone might know the answers to my questions i tought gold cannot oxide
1) what is gold oxide?
2) can gold oxide be chemicaly treated to get its form back to gold as in Au ?
Click to expand...

1) Gold oxide Au2O3 is the dehydrated form of Au2(OH)3. Made by precipitating concentrated HAuCl4 with soda ash to pH 6.5-7.
Dilute amounts will not precipitate.
2) Au2O3 or Au2(OH)3 dissolves in strong acids or alkali, but not weak.
Au2O3 or Au2(OH)3 + NaOH + H2O2 gives Au metallic
Au2O3 or Au2(OH)3 heated to 280C gives O3 + Au metallic (beware the ozone)
Au2O3 or Au2(OH)3 + HCl (Conc) gives HAuCl4-4H2O
HAuCl4-4H2O + SO2 gives Au metallic + H2SO4 (exothermic!!)
I hope this helps. Dr. Poe :|
 
hello again , as a newbie i just want to ask fellow experience refiners here some important questions

does HCL dissolve iron ? if it does will the pregnant solution show colors in stannous test? and what color could it be?

what indicates deep yellow to a light orange brown in stannous test colors ?

sometimes im getting a yellow reaction but with a ring outside as brown
or dark purple ring but in the middle is yellow and i get confused

ive been trying to dissolve computer IC's and gold pins in AR

a very warm thank you for your help fellas!
 

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and this one from a solution i digested
from a dental brace that they say has pt or pd
 

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The tests in the stannous 2 and 3 pictures appear to be platinum. I would suggest a test with DMG as well, to determine if there's any palladium present. The right hand test in stannous 3 makes me wonder.

HCl does, indeed, dissolve steel. The resulting solution is nearly clear of color, may have a hint of green. It should not respond to a test with stannous chloride in a meaningful way. Any values that may have been included with the solution will have been cemented by the steel. It's not clear to me why you're asking that question.

Harold
 
thank you very much harold , im practicing everything to learn and to do business in refining
thanks for your quick reply
 
good day everybody

have anybody here encountered putting ammonium chloride in a pregnant pt solution and nothing happened? not even a single reaction?
if so, what could be the reasons?
thank you very much in advance !
 
The platinum metals are notorious for not responding to chemical precipitation from dilute solutions. I expect that's likely the reason you achieved no results.

Can you say stock pot?

If that doesn't suit your fancy, you have the option of recovering the values with copper, or even to evaporate the solution until it is highly concentrated. That's not a good idea if you have already introduced ammonium chloride, however, as it will be troublesome as it is concentrated.

Stock pot looks good in such a case.

Harold
 
chemistrycoach said:
as a newbie, i hope you dont mind me asking harold .. er .whats a stock pot? thanks!
Click to expand...
A good question, best answered by having you read Hoke's book. It's all in there, and helps you understand why it's important for you to have one.

If you don't have Hoke's book, you can download a copy free of charge. Look for a link in the sig line of many of the readers. C.M. Hoke is her name. The book is excellent in that it will explain refining in a way that you will understand, even without knowing anything about chemistry.

Considering we try to be precise on this forum, I must ask. Is your upper case key broken? I don't mind being addressed as Harold, but I do take offense to being addressed as harold, as if I am not worthy of being addressed properly. I confess, it brings back unpleasant memories of the young girl that should have been addressing me as her father.

Please use the upper case when appropriate.
Harold
 
Hello again and good morning.

i have a jewelry that has pt in it ( know it because i bought it 15 years ago )
i digested it in AR for four hours in a light boil on a hotplate
tried to test the solution with stannous but only gives me a canary yellow result. no precious metal color
is my digesting method right? or should i digest in heat longer?
how long do we have to digest the pt in AR to let all the values come into solution?

thank you !
 
Pt test on stannous is orange.

The yollowcolor in your may just be the solution is not saturated with Platinum or very concentrated, or you did not eliminate excess nitric on the solution you tested, did the jewelry dissolve? is it solid platinum or is there another metal like gold or silver involved? if so how are you treating metal prior to trying to dissolve in aqua regia?

Pt boiled in aqua regia 4 hours have should dissolve enough platinum for a test of denoxxed solution,(platinum is not easy to dissolve), but if it the jewelry was silver plated with platinum you may need to eliminate silver before using aqua regia.

It does not sound like you have gold involved from your discription of the test unless free oxidizer is involved.
 

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