# gold powder



## chemistrycoach (Dec 25, 2011)

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 !!!


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## qst42know (Dec 25, 2011)

Yes, when the powder is rubbed it seems to bring out the shine.

What is your project?


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## chemistrycoach (Dec 25, 2011)

no project, just trying to learn first maybe next year i would dissolve some computer scraps thanks !


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## chemistrycoach (Dec 26, 2011)

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 ?


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## qst42know (Dec 26, 2011)

I usually check the wiki for a general over view.

http://tinyurl.com/7re9ldd


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## chemistrycoach (Dec 26, 2011)

thank you !


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## Dr. Poe (Jan 6, 2012)

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 ?



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 :|


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## chemistrycoach (Feb 17, 2012)

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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## chemistrycoach (Feb 17, 2012)

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


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## chemistrycoach (Feb 17, 2012)

and this one from a one piece earing that they say has Pt ?

thank you !


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## Harold_V (Feb 17, 2012)

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


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## chemistrycoach (Feb 17, 2012)

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


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## chemistrycoach (Feb 19, 2012)

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 !


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## Harold_V (Feb 19, 2012)

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


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## chemistrycoach (Feb 19, 2012)

as a newbie, i hope you dont mind me asking harold .. er .whats a stock pot? thanks!


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## Harold_V (Feb 19, 2012)

chemistrycoach said:


> as a newbie, i hope you dont mind me asking harold .. er .whats a stock pot? thanks!


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


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## chemistrycoach (Feb 19, 2012)

noted Harold thanks!


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## Harold_V (Feb 19, 2012)

Welcome, and thanks. 

Harold


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## chemistrycoach (Feb 22, 2012)

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 !


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## butcher (Feb 22, 2012)

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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## chemistrycoach (Feb 22, 2012)

hello again butcher !
no the earing did not dissolve, but the color of the solution turns to yellow after the first 30 minutes of heating, there is a lot of brown smoke fumes coming out ( i suspect nitric fumes ) and have a realy unpleasent odor. im prepared about this so i wear a mask and ventilated well the area
, after an hour or so the brown fume is no longer seen and the fumes are gone , it only gives out white evaporated smoke and i noticed that the AR is drying..so i added another 30ml of HCL... the solution is slowly turning to deep yellow ..but still no metal dissolve.. i test drop the solution in a cavity plate and drop freshly made stannous chloride .. but no reaction at all.. after which the solution in the beaker turned red orange..total hours digesting 3 HOURS.
i stop at this point thingking i might go no where..
i saw lazer steves video about platinum refining .. he mentioned there that he dissolve ( complete dissulution ) the platinum for 12 hours?

thank you very much butcher 

ps
i bought the pair of earing from a jewelry shop longtime ago 2 grams each earing... and it is platinum according to the jewelry shop owner ( kinda reputable shop)
but i realy dont know if it had silver or gold in it. i plucked out the little diamond stone prior to this...


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## butcher (Feb 22, 2012)

From reading your post it sounds like you did not eliminate nitric acid before the test, this can be done with a small amount of solution few drops in test tube, over a candle flame, a pipette is handy to add a drop of HCl to re-wet solution as it concentrates and fumes off NOx gas, the last evaporation I would leave some what concentrated and put q-tip in the tube to wet it then retest with stannous chloride.

You need to know if you have value in your solution.

If I only had small earrings, and was not sure if they had silver (you can test for silver with schwerters solution in a filed notch), I would just process them with my dental scrap in-quarter with silver and the gold and dissolve in nitric before proceeding to aqua regia, or I could mix them in the next big silver melt and get the Platinum when I built that silver cell I have in my dreams (getting an accumulation of silver it hopefully will not be long till that dream comes true).


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## qst42know (Feb 23, 2012)

> there is a lot of brown smoke fumes coming out ( i suspect nitric fumes ) and have a realy unpleasent odor. im prepared about this so i wear a mask and ventilated well the area



You do know no mask is truly effective against nitric fumes except an air supplied mask.

You also know Platinum salts are highly toxic and once you have become sensitized to these compounds you cannot be around them ever again. The unpleasant odor is telling you something and you aren't listening.



> i saw lazer steves video about platinum refining .. he mentioned there that he dissolve ( complete dissulution ) the platinum for 12 hours?



Platinum in a catalytic converter are very small molecules already, the time to dissolve jewelery is going to be vastly different.


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## chemistrycoach (Feb 23, 2012)

thanks for the precious advices qst42know and butcher.
i will do it with best safety precautions.

may i ask these questions for my practicing

what is an oxidizer? i heard that oxidizers prevent stannous detection and precipitation if there are values in a solution?
if so, how can we get rid of it?

why does my jewerly materials cause the HCL to turn yellow? ( because i wash my materials first with hcl heated for 10 mins , decant and replace AR )

how will i know when mild boiling that if nitric is already gone in my AR solution with the material in it?

i would like to know if i already have some values of my jewelry in the solution so....

after 3 hours of boiling i test to put a little drop of the solution in a cotton ( with no stannous ) the result is deep yellow

then i put another drop of it in cotton ( now with stannous chloride ) stiill no color change but the same deep yellow solution

i drop a second drop of the solution again in the same cotton with the stannous in it and it turns out an s dark orange color in the middle.

is it already ripe for precipiating? or i might be going no where

i realy would like to be a refiner and im bent on learning and read hokes every night but still some scenario presents problems that was not tackeld in the book.

thanks a lot guys!

ps
the solution when i left is dark orange and the jewelry is still in there i think unharmed..in AR ( 3 parts HCL 1part nitric ) cp pure


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## butcher (Feb 23, 2012)

Oxidizer in your case is the nitric acid in your aqua regia, it sound's as if you still have some free nitric acid (oxidizer) in solution (and several additions of stannous to test), evaporate solution down to a concentrate solution (this is to gas off the NOx fumes from the nitric in solution, add just a little HCl, repeat two times, last evaporation leave solution concentrated but do not get it so concentrated (when hot) that it forms salts when cooled, you will usually notice brown fume when HCl added.


The free nitric re-dissolves your metal in the stannous chloride test, it will also do the same when trying to precipitate the metal from solution, depending on how much platinum you have in solution would determine whether to try and precipitate or to just pour it into stock pot ang collect it when you have more(two small ear rings and not much dissolved you may not have much in solution).

If only working with small amounts this would not be my choice of processing, to easy to lose values from small lots.


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## chemistrycoach (Feb 24, 2012)

thanks again butcher your a big help!


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## chemistrycoach (Feb 28, 2012)

howdy ! what material has alkaline? ........ what connectection does alkali or alkaline have in dissolving gold in AR?......i read hokes but cannot fully absorb the literature, does alakaline in AR cause problems in refining? a liitle knowledge is very much appreciated!


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## butcher (Feb 28, 2012)

Alkali or alkaline is the opposite of acid.

pH is a (logarithm) scale we use to measure acidity or alkalinity (opposite of acid), this scale is numbered 0 to 14
An alkaline has a high pH on the scale (example pH 12), water is neutral about pH 7, a acid will be low on the pH scale (example pH 2).

To dissolve gold we use acids. I am not sure what you are referring to in Hokes book, but if we added alkaline substance to gold in solution we could precipitate gold (depending on conditions), actually if gold was precipitated and added to a very strong excess of an alkaline hydroxide we could actually make a solution of gold hydroxide.

Normally we would not want an alkaline in our acidic gold solution, I am not exactly sure if this answers your question as it is a bit unclear to me what you are asking.

some alkaline things, sodium hydroxide, baking soda, soda ash, wood ash, sodium carbonate.


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## chemistrycoach (Feb 29, 2012)

hi butcher ! im just collecting knowledge on hand or by the book for future references, but that is realy a great explanation even for a non chemsit or refinist to understand , so easily explained, thank you very much i realy appreciate it !


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## Oz (Mar 23, 2012)

In reading about your digestion of the pair of ear rings totaling 4 grams and your solution going from clear –> yellow -> orange -> red, and you are not getting a stannous chloride result when testing, I’m betting your stannous is no good. Make a gold standard test solution out of some card edge fingers so you can test your stannous. Your reaction sounds as I would expect for a platinum digestion with your color changes.


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