Stannous test Ag + PGMs &/or ?

[kurt]

OK – I have 2 Ag solutions dissolved with 67% tec grade nitric. – First solution (this post) is from current batch of contact points. - Second solution (next post) is from my test bar recovered from the hypro (sulfide) material I have.

What has me confused is the black. I would almost think I had gold but this is a silver nitrate solution.

I did a 2 blot test on each solution. Top blot is stannous then solution. Bottom blot is solution then stannous. One pic is right after drop test – the other pic is same test after photo exposing to sun.

The AgCl is evident as the white Cl that photo changes when exposed to the sun.

The Pt/Ir would be the orange/brown ? (from Hokes Pt/Ir deep yellow – brown almost black if concentrated) So this could be the black ?

(from Hokes Pd starts deep yellow like Pt turning blue green after a few minutes) So is the black a skewed color of the Pd due to the multiple metals – or something else

The black appears instantly followed very quickly by the AgCl (almost instantly) then the orange/brown starts to appear taking about a minute to come to full color

Kurt

 

[kurt]

This is the second solution which is from the 28.4gram bar that I got from the test melt of the hypro (sulfide) material I have. I also got a fair amount of sediment that didn’t dissolve in the nitric which I will be trying some AR on.

Kurt

 

[samuel-a]

Test with DMG to confirm or eliminate Pd.

If you don't have any, Patnor has a very reasonable listing on eBay for DMG test solution.

 

[kurt]

I do have some DMG but I can't find it right now. I have been working on building my new lab & other things so lately things have been getting moved around a lot & are totaly un-organized. :x It sure will be nice when it's all done with things back to orginized.

Kurt

 

[kurt]

Ok – found my DMG – after doing a DMG test on the solutions I got the yellow Pd precip on both solutions. Then did another stannous test & this time got just the AgCl with the black outside ring – so at this point & time will have to assume that in this situation with combination of metals the black is Pt --- unless it is just silver doing a quick photo color change?

I find this interesting as the colors are not characteristic to the colors described by Hokes or the Q-tip test pics provided by Laser Steve. (which is why I posted the question to start with) (I am still learning)

This pic is the results of the sediment from the 28.4 gram bar I got from my test melt of the hypo (sulfide) material I have.

What I did (after the original melt with rebar & pouring the bar)

I re-melted the bar & poured into water to corn flake – dissolved in nitric – filtered sediment out – tested solution with stannous & got the colors posted here in my second post – tested solution with DMG & got “very” evident Pd precip – re-tested with stannous & got primarily AgCl & black outside ring (which at this point I assume is PT being as how orange/brown color went away after DMG test) – I then washed the sediment in the filter good, till I no longer got AgCl in wash water – dried the sediment/filter – put a bit of sediment in my glass test spoon & added a bit of AR – applied a bit of heat till reaction stopped – tested with stannous & got a very evident Au result 8)

So it is looking like Dr Poe was right about the possibility of the sulfides from hypo being able to contain Au, Pt & Pd in amounts worth recovering.

What I don’t know – is what the un-dissolved sediment after AR treatment might be?

Kurt

 

[Dr. Poe]

Wow, Kurt, I am impressed and bewildered. Not knowing the origin of the metals, I couldn't tell what the remnants might be.
Unless its platinum from silver platinum nitrate (reduced by light to metal). But that's just a wild guess. Still, it's seldom that I am so impressed or bewildered! :roll: Dr. Poe

 

[samuel-a]

Wow, Kurt, I am impressed and bewildered. Not knowing the origin of the metals, I couldn't tell what the remnants might be.
Unless its platinum from silver platinum nitrate (reduced by light to metal). But that's just a wild guess. Still, it's seldom that I am so impressed or bewildered! :roll: Dr. Poe

Indeed. Nice detective work Kurt!

 

[kurt]

Dr Poe the 28.4 gram bar which I have now determined to contain primarily silver but also Au, Pt, & Pd came from a test melt from the hypo (sulfide) material that I posted question about in a thread titled - “metals from pictures fixer solutions” – here under “help needed” – It got a bit controversial as to whether or not such hypo sulfides contained only silver or silver & other PMs. It also resulted in a discussion about acetylides.

Now back to the reason(s) why I posted this thread. – The first was because the colors I was getting in my testing where not characteristic to what should be expected (the black especially had me confused)

However – determining what I had in solution (due to the fact that test colors where not characteristic) was actually leading up to questions I have about parting in a silver cell.

Everything I have read about using a cell to attain a high purity silver tells me the feed stock (anode bars) need to be 98% or better to start with.

The stannous test (&/or DMG test) only tell me what I have in solution – not how much of each.

So – what I know is that after cementing – the bars I pour will contain primarily silver but also Cu, Pt & Pd --- So my real question is – how do these other metals effect the parting in a silver cell “if” they are in amounts that make my bars less then 98% silver.

I know this is one of those questions that has been asked & answered before & my problem isn’t that I haven’t researched setting up & running a cell – my problem is that I have read so much that it has made my head spin – in fact I am sure I read the answer in all the reading I have done, it’s just been lost in all the reading I have done --- so if nothing else some links back to articles would be helpful.

What I seem to remember is that copper eventually pollutes the electrolyte eventually causing parting problems – so is it just the copper content that needs to be 2% or less? – or ???

Again – links to articles about the effects of feed stock purity would be helpful

Thanks
Kurt

 

[samuel-a]

Kurt

Eventually, all electrolyte solution goes foul.
It's just a matter of anode purity and how many anodes had been processed.

As you know, in the slimes you can expect to find Au, Pt, Pd and Ag, the last three (+ Cu) will also be in solution, where the vast majority of the solution of course is Ag.
At some point, depending on Temp' and voltage but mainly concentration, they will start co-deposite with the silver. Each has it's own threshold.

The point is, that you need to make sure to eliminate as much contaminates as you can before pouring the anodes. Such as proper washings, Pd precipitation with DMG, addning nitre+borax to the melt...
I have coverd it in my tutorial here:
http://goldrefiningforum.com/phpBB3/viewtopic.php?f=52&t=12275

 

[Dr. Poe]

Air injection into the top 1/4 inch of a melt will rid your silver of copper. Dr. Poe

 

[samuel-a]

Air injection into the top 1/4 inch of a melt will rid your silver of copper. Dr. Poe

Yes, that a good way to eliminate BM.

I had before a ceramic alumina pipe (drinking straw size) , i used it to pump pure O2 from a cylinder into a doré melt (scrap 14K).
It did good, though didn't clean ALL base metals since at some point the gold, so i assume, protected other metlas from oxidation as its concentration went up, i couldn't follow up on this since i accidently broke it a short while after and never got the chance to buy a new one.

I covered the melt with few teaspoons of borax and injected the oxygen from about the middle of the melt. I reckon it was about an 1/2 inch deep.
Nitre is just another way of adding oxygen...

 

[Dr. Poe]

Air injection into the top 1/4 inch of a melt will rid your silver of copper. Dr. Poe

Yes, that a good way to eliminate BM.

I had before a ceramic alumina pipe (drinking straw size) , i used it to pump pure O2 from a cylinder into a doré melt (scrap 14K).
It did good, though didn't clean ALL base metals since at some point the gold, so i assume, protected other metlas from oxidation as its concentration went up, i couldn't follow up on this since i accidently broke it a short while after and never got the chance to buy a new one.

I covered the melt with few teaspoons of borax and injected the oxygen from about the middle of the melt. I reckon it was about an 1/2 inch deep.
Nitre is just another way of adding oxygen...

Larger refineries use air, then pour, remelt and use chlorine gas. 4 to 10 lbs pressure. Overdo the pressure or the time and gold will vaporize as a purple fume. Chlorine slags off even silver. Dr. Poe

 

[prospect88]

When I use to work at a refinery we use to melt placer gold, once molten we would add the chlorine gas to send the silver to the slag which would be a nice purple color. I didn't know the purple fume was a sign of gold vaporizing but then I was just learning. I now have to wonder how much gold headed to the scrubber!

Larger refineries use air, then pour, remelt and use chlorine gas. 4 to 10 lbs pressure. Overdo the pressure or the time and gold will vaporize as a purple fume. Chlorine slags off even silver. Dr. Poe[/quote]