HAuCl4
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Nice kitchen! 8)
Mixed Black PGM Powders
- Thread starter kadriver
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It would be just easier to use dilute acid peroxide and dissolve the platinum that way. Or even dilute aqua regia. As long as it doesn't get very hot, it won't dissolve much of the rhodium. The sulfuric acid treatment works on rhodium black, but it requires a lot of heat and the fumes it makes are carcinogenic (SO3) and very disagreeable. I ought not to have recommended it. It is a great qualitative test for Rh though!
kadriver
Well-known member
Lou - thank you for the heads-up about those fumes - I have seen them from an overheated sulfuric acid pickling solution one time.
My goal is to get the platinum from the rhodium. I am not overly consumed with getting any of the rhodium.
My concern is this; by dissolving the powders with dilute AP or dilute AR, I'm bound to get some Rh in with my Pt.
I would like to end up with the nice yellow colored precipitate of the platinum salt (is it called Ammonium Hexachloroplatinate?) for calcining to platinum sponge.
Since I use a refiner who will melt it for me, I do not intend to melt any platinum or palladium myself. I'll let the big refinery do that for me.
Here is my plan/procedure;
I have a reflux condenser with ground glass connections.
My plan to remove the Rh from the Pt with sulfuric is to do the reaction outdoors with the reflux condenser in place to minimize fumes going into the atmosphere.
I will put some sand in a corningware casserole and place the round flask in the sand (not too deep) for heat distribution.
Once in place, I'll slowly add the concentrated sulfuric acid (with heat off) until it is all in the flask - about 150ml for the first reaction.
I'll do this with all the proper safety items, clothing, goggles, respirator.
Then set up the condenser and start the water flow via recirc pump in a 5 gal bucket of icewater, turn on the heat - and get inside the house and monitor from a nearby window.
Once it looks like the reaction is complete (judging by the fumes in the reaction vessel) then I will turn off the heat and leave the waterflow through the condenser until everything reaches room temp.
Carefully decant the acid/Rh solution and set it aside in a sealed container for cementing with zinc later on, then repeat until the acid is clear.
I need the money from the platinum as the material for refining gold and silver has dropped off like a ski-jump.
Plus I would like the benefit of the education provided by the experince, and to complete the process and complete this thread/post.
Once I have gotten all the PGMs from these cats, I am going to retire from PGM refining - much too involved and dangerous!
Thank you for all the help you have given - kadriver
My goal is to get the platinum from the rhodium. I am not overly consumed with getting any of the rhodium.
My concern is this; by dissolving the powders with dilute AP or dilute AR, I'm bound to get some Rh in with my Pt.
I would like to end up with the nice yellow colored precipitate of the platinum salt (is it called Ammonium Hexachloroplatinate?) for calcining to platinum sponge.
Since I use a refiner who will melt it for me, I do not intend to melt any platinum or palladium myself. I'll let the big refinery do that for me.
Here is my plan/procedure;
I have a reflux condenser with ground glass connections.
My plan to remove the Rh from the Pt with sulfuric is to do the reaction outdoors with the reflux condenser in place to minimize fumes going into the atmosphere.
I will put some sand in a corningware casserole and place the round flask in the sand (not too deep) for heat distribution.
Once in place, I'll slowly add the concentrated sulfuric acid (with heat off) until it is all in the flask - about 150ml for the first reaction.
I'll do this with all the proper safety items, clothing, goggles, respirator.
Then set up the condenser and start the water flow via recirc pump in a 5 gal bucket of icewater, turn on the heat - and get inside the house and monitor from a nearby window.
Once it looks like the reaction is complete (judging by the fumes in the reaction vessel) then I will turn off the heat and leave the waterflow through the condenser until everything reaches room temp.
Carefully decant the acid/Rh solution and set it aside in a sealed container for cementing with zinc later on, then repeat until the acid is clear.
I need the money from the platinum as the material for refining gold and silver has dropped off like a ski-jump.
Plus I would like the benefit of the education provided by the experince, and to complete the process and complete this thread/post.
Once I have gotten all the PGMs from these cats, I am going to retire from PGM refining - much too involved and dangerous!
Thank you for all the help you have given - kadriver
It will be faster and more effective to use HCl and peroxide a la lazersteve or perhaps 3M aqua regia with slight heat. Sulfuric works, but you won't easily filter that solution and it is so colored you can't easily tell when solids go out.
Best,
Lou
Best,
Lou
kadriver
Well-known member
Lou said:
OK Lou - I'll skip the sulfuric acid and go with HCl and peroxide at room temp for the digetion of the Pt - I have some 40% H2O2 bought from "Sallys Beauty Supply".
There is probably not much Rhodium in there anyway.
I have worked with sufuric acid from a gold stripping cell - I had to dilute the resulting acid from that cell with 20 volumes of water before I could filter out the black gold mud from the acid.
Once I am certain that all the nitric acid is out of the remaining black powders with pH test strips, then I will use gentle heat to drive off any moisture before adding the HCl.
I have a seperation funnel with a valve that can be adjusted to allow a slow drip of H2O2 into the container holding the Pt black and HCl on a stir plate with a stir bar.
I can set it up and start the drip, then get inside away from the chlorine gas generated by the drip.
I guess that I will have to live with some Rh contamination in my platinum.
Or is there a Pt repurification process that can be used to remove the Rhodium in a different way - similar to the way that the palladium was handled earlier in this post?
kadriver
kadriver
Well-known member
Are there any spot plate tests that I can do to a small sample of the black powders that will selectively check for the presence of rhodium?
Stannous chloride would be one good indicator, but if there is even very slight Rh contamination, the solution left over from precipitating the ammonium hexachloroplatinate will be a vivid bright pink!
FYI, the dilute "lazersteve" method of separating Pt from Rh and Ir works remarkably well. I call it the lazersteve method because I saw Steve employ it on some iridium containing med material and then saw the resultant platinum product. If time is not an issue, it is the pre-eminent way.
Low and slow!
Low and slow!
kadriver
Well-known member
I am still waiting for the last distilled water washing of the remaining black powders to settle - it takes days for it to happen all the way.
I printed out the test for Rh provided by lazersteve - I did not want to disturb the washed powders until they settle completely - once settled, I'll do the test for Rh.
I'll search the forum for the dilute method you referenced Lou - thank you.
In the mean time, while waiting for the washings to settle, I went back to some of the palladium solutions left from the palladium refining.
I printed out the test for Rh provided by lazersteve - I did not want to disturb the washed powders until they settle completely - once settled, I'll do the test for Rh.
I'll search the forum for the dilute method you referenced Lou - thank you.
In the mean time, while waiting for the washings to settle, I went back to some of the palladium solutions left from the palladium refining.
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kadriver
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kadriver
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Back to the palladium solutions;
Beginning with the large two liter beaker - it contained the wash water that was allowed to evaporate naturally to concentrate.
I began by filtering to remove any solids from the solution.
Then I prepared a saturated solution of dimethyl gloxime (DMG) to scavenge the palladium from the solutions.
I made the DMG solution by adding about 2 or 3 grams to 200ml of distilled water, then heating to near boiling to get the powder into solution.
I don't use any solvents when preparing my DMG solution - Just hot water seems to do nicely.
Once the Pd solution was filtered, I began adding the DMG to the filtered solution a few ml at a time.
The precipitate began to form immediately starting out as a yellow cloud in the solution, then getting much thicker.
As the precipitate settled, I noticed that the liquid was still quite yellow, so I added more hot DMG and more precipitate was formed.
Eventually, all the palladium DMG came out of the solution.
Beginning with the large two liter beaker - it contained the wash water that was allowed to evaporate naturally to concentrate.
I began by filtering to remove any solids from the solution.
Then I prepared a saturated solution of dimethyl gloxime (DMG) to scavenge the palladium from the solutions.
I made the DMG solution by adding about 2 or 3 grams to 200ml of distilled water, then heating to near boiling to get the powder into solution.
I don't use any solvents when preparing my DMG solution - Just hot water seems to do nicely.
Once the Pd solution was filtered, I began adding the DMG to the filtered solution a few ml at a time.
The precipitate began to form immediately starting out as a yellow cloud in the solution, then getting much thicker.
As the precipitate settled, I noticed that the liquid was still quite yellow, so I added more hot DMG and more precipitate was formed.
Eventually, all the palladium DMG came out of the solution.
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kadriver
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kadriver
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kadriver
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I added a blob of the palladium DMG precipitate to the ammonia solution in the same beaker from the earlier palladium refining.
I was not sure if it would cause a vigorous reaction or not - but the reation was very low.
Using a pipette, I rinsed the precipitate from filter into the beaker with 10% ammonium hydroxide solution.
I was not sure if it would cause a vigorous reaction or not - but the reation was very low.
Using a pipette, I rinsed the precipitate from filter into the beaker with 10% ammonium hydroxide solution.
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kadriver
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The stir bar was still in the ammonia solution, so I placed the beaker with the newly added palladium DMG precipitate on the stir plate and added low heat.
After a minute or so on the stir plate, the whole thing turned redish pink colored - I hope I did not make a mistake here because I was not expecting that color.
this is as far as I got today - low & slow is the ticket. I still have the other palladium solutions to scavenge with DMG - more to follow.
kadriver
After a minute or so on the stir plate, the whole thing turned redish pink colored - I hope I did not make a mistake here because I was not expecting that color.
this is as far as I got today - low & slow is the ticket. I still have the other palladium solutions to scavenge with DMG - more to follow.
kadriver
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kadriver
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After more stirring and more heat, I filtered the liquid to retreive the palladium solution.
After retreiving the valuable palladium dissolved in ammonia, I used 10% ammonia (from Ace Hardware) to rinse the solids back into the beaker for more stirring and heat.
After retreiving the valuable palladium dissolved in ammonia, I used 10% ammonia (from Ace Hardware) to rinse the solids back into the beaker for more stirring and heat.
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kadriver
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kadriver
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kadriver
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I added a few ml of 31.45% hydrochloric acid to the the filtered liquid.
The solution immediately turned cloudy, then the bright yellow precipitate began to form.
At first it did not look right - too light in color - almost a pale tan color on top and bottom with a band of yellow in the middle.
It looked as though I had made a mistake.
But after sitting for a while it turned bright yellow.
The solution immediately turned cloudy, then the bright yellow precipitate began to form.
At first it did not look right - too light in color - almost a pale tan color on top and bottom with a band of yellow in the middle.
It looked as though I had made a mistake.
But after sitting for a while it turned bright yellow.
