# Rh time period...



## dmarth10 (Oct 22, 2008)

I just added AR to my recovered pgms from a catalytic converter. There is no gray powder left at the bottom of the bowl. I was wondering how long the Rh takes to dissolve into AR. I heated the solution to about 160 F. Or does this just mean that I recovered no Rh?


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## Lou (Oct 22, 2008)

Rhodium does dissolve in aqua regia to a limited extent--it's more empirical than scientific--depends on temp., conc. of solution, and the surface area of the rhodium.

Palladium goes into cold aqua regia, platinum will not to any real appreciable extent.

Rhodium goes into hot aqua regia in certain circumstances.

If you suspect rhodium in your sponge--first, boil sponge with nitric acid to remove any palladium. Rinse until there is no more yellow solution, and boil again, checking for more yellow. Then take a small sample of your sponge and put it in a tube with concentrated sulfuric acid (18M, d. 1.84) and heat until you see white vapors forming). If it turns brown-red then you likely have rhodium. It is a good qualitative test, but Pd and organics can throw it off.

Lou


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## lazersteve (Oct 23, 2008)

Since Lou mentioned it, here's what you are looking for with the hot concentrated sulfuric test:

[img:722:1388]http://www.goldrecovery.us/images/rh_test2.jpg[/img]


Thanks again Lou, I really liked this one and have been using it quite a bit since you told me about it.

I use this method for metallic solids suspected of containing Rh.

I use the hot stannous test for solutions suspected of containing Rh.

Here's a positive test for Rh in solution:

[img:640:356]http://www.goldrecovery.us/images/pt_rh_test.jpg[/img]

The vial on the left contains Rh.

Steve


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## buffa1o1 (Dec 23, 2008)

<b>This photo is the results I had following Hoke's Platinum experiment using a solution made from electroplating scrap 
(pages 105-108 in Hoke's book):</b>

[img:600:206]http://native-americans.org/platinum-test-1.jpg[/img]

<b>Any opinions?</b>

I have have asked a couple of eBay sellers offering advise who had differing opinions about the results of my experiment, 
including one that said the percipitated powder will only be red if it is platinum and that Hoke must have been color-blind 
because platinum will not percipitate an orange powder as stated in the book. 

I first dissolved the base metals in heated Nitric acid made from strong Sulfuric acid (Rooto) and Sodium Nitrate. I realize 
this was a mistake because I am sure that I also dissolved some Palladium and other pm but saved my solution to re-work later.

I washed & rinsed the recovered flakes/dust several times, then dissolved them in 4 parts muriatic acid and 1 part clorox, then 
added 3 more parts water and percipitated the gold with SMB. 

The solution at this point tested a rosey red color with the stannous test so I concentrated the solution to about 1/5 it's 
original volume, tested with stannous and received the above pictured result. 

I then used 1/2 fl. oz. of the concentrated solution which I had dropped the gold from to conduct Hoke's platinum experiment 
by adding heat (not mentioned in Hoke's experiment) and Ammonium Choride to percipitate about a heaping tablespoon of 
the orange powder in the photo.

I dried the orange powder then sintered it on porcelain down to a slightly darkish grey powder with a slight hint of red hues, 
it produced a loose but spongy powder. (the color of the sintered material is much more grey under good light than it shows in 
the picture and does not match the color of the actual sintered powder very well but the color of the swatch and the 
percipitated orange powder are a close color match)

I then dissolved a small amount of the grey sponge in an AR solution made from Sodium Nitrate and Muriatic acid, I heated it 
to dissolve the grey sponge into solution and then used the stannous cloride test and it showed a light rosey red colored 
stain (not pictured).

I could use some help on this because I have a fairly large batch of the concentrated solution (about 80 fl. oz). I think the 
solution I used in the experiment may still contain a little Gold, some Platinum group metals and I do not want to miss any values. 

Note: The enlarged text is not an attempt to shout, It is just easier to read for some of us 

<b>Any comments or advise is appreciated.</b>


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## Lou (Dec 23, 2008)

Welcome to the forum!! You seem to have a good idea of what you're aiming to do. Unfortunately, it seems as if some of the eBay people are trying to keep a good man down, or maybe they just don't know what they're talking about  So relax, perhaps make yourself a strong eggnog, take a break and we'll go over this. 



buffa1o1 said:


> I have have asked a couple of eBay sellers offering advise who had differing opinions about the results of my experiment,
> including one that said the percipitated powder will only be red if it is platinum and that Hoke must have been color-blind
> because platinum will not percipitate an orange powder as stated in the book.



I've precipitated a goodly amount of platinum, and if you're doing it right, and you're precipitating with ammonium chloride solution, then you will be seeing a canary yellow precipitate. This indicates that everything has gone as well as it could and you've made a very pure precipitate of ammonium hexachloroplatinate. If it is slightly orange, it's passable stuff, but it should still be refined once more. If it's pumpkin orange bordering on orange-red, that usually indicates that there's significant Pd contamination, so try again. Palladium, when precipitated out as ammonium hexachloropalladate, is brick red wet and will take a nice pretty red color as it dries.



buffa1o1 said:


> I first dissolved the base metals in heated Nitric acid made from strong Sulfuric acid (Rooto) and Sodium Nitrate. I realize
> this was a mistake because I am sure that I also dissolved some Palladium and other pm but saved my solution to re-work later.



Sulfuric acid does attack palladium, especially when it is in finely divided or thin foil form. So too does your nitric acid. If your solution went quite brown in appearance, then you probably had a lot of Pd in there, if you dilute it you will see a rich yellow color. Now be careful here, Pd ion in solution has a very intense yellow coloration, so intense that it looks brown when concentrated. Ferric nitrate (iron III) can also have a yellow color in acid solution, but it's kind of bland. The best way to know the difference is to dissolve iron in nitric and dissolve Pd in nitric, one has a much richer yellow. Make sure you get a stannous test and look for the green Pd!



buffa1o1 said:


> I washed & rinsed the recovered flakes/dust several times, then dissolved them in 4 parts muriatic acid and 1 part clorox, then
> added 3 more parts water and percipitated the gold with SMB.



Excess water isn't usually a good thing, especially if you're going after an element that's just a trace. Keep your solutions concentrated. I'm assuming you had a positive gold stannous test (which can be difficult to ascertain with other things in there).



buffa1o1 said:


> The solution at this point tested a rosey red color with the stannous test so I concentrated the solution to about 1/5 it's
> original volume, tested with stannous and received the above pictured result.



Good, good! Concentrate it!



buffa1o1 said:


> I then used 1/2 fl. oz. of the concentrated solution which I had dropped the gold from to conduct Hoke's platinum experiment
> by adding heat (not mentioned in Hoke's experiment) and Ammonium Choride to percipitate about a heaping tablespoon of
> the orange powder in the photo.
> 
> ...



Ok, you're doing this mostly right. After the heat though, you should cool it in an ice bath. Once your Pt has precipitated, filter it and rinse with ice cold saturated ammonium chloride solution. Now look at the filtrate (the liquid, not the precipitate) and see if it has any residual yellow color to it; if it is faint, then there's probably not that much Pt left in it, but you can do a stannous test against standard solutions of known concentration to get a good guestimate. If you're going for broke and don't care about the other metals beside Pt in the filtrate, you can get all of the last Pt group out of that solution by cementing with zinc and boiling that reduction in HCl to remove excess zinc. That powder can then be tossed into the next batch you refine.

Your orange powder should've done some weird things when you heated it, like turning dark and releasing lots of white smoke (ammonium chloride). You have to go low and slow with the heat or you can gas phase transport your money into thin air. IF there's a slight reddish hint left to your reduced platinum sponge, then you need to heat it again til it's gone, or boil in nitric and see if there's any color change. If there is, then you didn't eliminate all of the base metals. This material, properly reduced should be a heavy gray sponge.



buffa1o1 said:


> I then dissolved a small amount of the grey sponge in an AR solution made from Sodium Nitrate and Muriatic acid, I heated it
> to dissolve the grey sponge into solution and then used the stannous chloride test and it showed a light rosey red colored
> stain (not pictured).



This was good, but you should've first boiled in hydrochloric (muriatic acid) *or *in nitric to remove any crap that might have been dragged down. It's an additional purification step. Then you give it the 'ol aqua regia treatment and get a nice dark red solution.



buffa1o1 said:


> I could use some help on this because I have a fairly large batch of the concentrated solution (about 80 fl. oz). I think the
> solution I used in the experiment may still contain a little Gold, some Platinum group metals and I do not want to miss any values.



80 fluid ounces of this? Someone will be having a very nice Christmas! Just make sure you know what concentrated means when you're dealing with the PGMs, to me, conc. is over 10 troy ounces per liter of solution. 
All in all, not a bad shot at this.



buffa1o1 said:


> Note: The enlarged text is not an attempt to shout, It is just easier to read for some of us
> 
> <b>Any comments or advise is appreciated.</b>



As for the font, no big deal!

The only thing that bugged me is percipitated. It's _precipitated_. I swear I'm not a grammar Nazi. 

Again, welcome to the forum. I hope I helped you out. Keep the pictures coming and we'll be sure to make sure you're doing this right.

So far, it seems like you've got most of it quite well. 

Happy Holidays,
Lou

EDIT: Just curious, but did you use more ammonium chloride than you were supposed to? The precipitate looks O.K color wise, but not physically: I've seen some people here use too much ammonium chloride and get different crystals.


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## buffa1o1 (Dec 23, 2008)

<b>Awesome reply Lou</b> 8) I appreciate the encouragement and offer to help me get this done right. I wil try to make my contributions to the forum positive, constructive, and use my spell checker . I knew it was precipitate but I'm part indian and we always leave one mistake in our work to show we are not perfect like the Creator! :lol: Had you going there, huh?

I have checked out several sites and this forum has a lot of expert information to find once you learn to navigate the search features. Great website! 


> if you're doing it right, and you're precipitating with ammonium chloride solution, then you will be seeing a canary yellow precipitate.


My son corrected me that the dried precipitate is very much a canary yellow and not orange as I stated. I did notice that when I heated the solution in the beaker, I got it a little too hot at one point and the solution that dried on the beaker formed 2-3 tiny but very red specks at the top of the solution which went back into solution as I swirled the solution around. I suspected at the time that it was pd contamination and decided to make my previous post to get some tips. 

By your description of what the precipitate color should be and my son's assessment of the color, I think the contamination is not too bad but I do plan on very carefully processing it again after I feel confident in my knowledge & skills at following correct procedure. 


> I'm assuming you had a positive gold stannous test.


As you stated, it was a difficult stannous test but and it did show some purple and I trusted the seller who stated it did contain some gold. 


> you should cool it in an ice bath. Once your Pt has precipitated, filter it and rinse with ice cold saturated ammonium chloride solution.


I did not cool it in the ice bath as you stated and that is probably why the solution is still a nice yellow color and it still shows a pretty, rosey colored stain with the stannous test. 


> Your orange powder should've done some weird things when you heated it


I heated the orange powder low & slow on a hotplate until it barely fumed a white smoke and it went through some wierd phases as you described, it took about 2 hours or more at this temperature to turn it all into the grey powder.


> 80 fluid ounces of this? Someone will be having a very nice Christmas!


I forgot to mention that I also caught a nice pile of very white, silver colored metal that did not dissolve in the hcl cl solution. I tested a dab of this in boiling sulpuric acid and the smaller particles dissolved turning the solution a reddish brown making me suspect it is rhodium. I definately won't have this worked out by Christmas but with a little guidance, I may have a long awaited payday soon :wink: 


> Just curious, but did you use more ammonium chloride than you were supposed to? The precipitate looks O.K color wise, but not physically: I've seen some people here use too much ammonium chloride and get different crystals.


The physical traits were altered after I dried it because I crushed it using a safety razor blade figuring it would sinter easier if the clumps were broken down some. 

I did use more ammonium chloride saturated solution than Hoke called for but it was very slow to start precipitation so I kept adding it until it showed signs of precipitation. At this point I had added all of the ammonium chloride in the saturated solution Hoke's experiment called for which was supposed to be enough to do the rinse and I was forced to make up more to wash, rinse and filter the orange powder. As the solution cooled, more and more percipitate formed, I wish I had done the ice bath now. :roll: 

I will follow your advise and I will post more images as I progress. Thanks again!


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## Platdigger (Dec 23, 2008)

This platinum is from "electroplating scrap"?

If I may, what do you mean by this?
Randy


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## buffa1o1 (Dec 23, 2008)

Hi Randy:

I purchased a small box of scrap that the seller said came from his grandfather's estate. He said his grandfather had kept this scrap for many years and that the contents were used in some part of the plating process at a shut-down Gold, Platinum & Rhodium plating plant. Under the thick coat of pm plating were just some tangled & randomly bent stainless steel wires.

I hope this helps,
Scott


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## Platdigger (Dec 23, 2008)

I see, thanks.

Just a thought, but are you sure those wires are just stainless and not pt/rh thermocouples? 
Randy


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## buffa1o1 (Jan 8, 2009)

*Photo's of Platinum in precipitation using Hoke's Platinum experiment
(pages 105-108 in Hoke's book):*

[img:293:300]http://shillingstad.com/gold-forum/100_1110-a.jpg[/img][img:400:300]http://shillingstad.com/gold-forum/100_1113-a.jpg[/img][img:225:300]http://shillingstad.com/gold-forum/100_1115-a.jpg[/img]

[img:351:297]http://shillingstad.com/gold-forum/100_1116-a.jpg[/img][img:306:300]http://shillingstad.com/gold-forum/100_1119-a.jpg[/img]

*Click on image for a close-up.*


> Just a thought, but are you sure those wires are just stainless and not pt/rh thermocouples?


Thanks Randy! I did more tests and they are only stainless steel wires.


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## Noxx (Jan 8, 2009)

Very nice close-ups, thanks


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