# Distilling and isolating the OS and Ru from a dirty leach



## lazylightning (May 27, 2008)

Hi Everybody!

So here it is, I've followed a process for removing the OS and Ru from a dirty pgm leach by distilling them off as diammonia oxychlorides.

A leach needs to be boiled off to kill the oxidant anyway, so I followed a suggestion to add a little ammonia chloride to the leach before distillation boil off. I used a vacuum pump too, makes it more quick and efficient, since under a real good vacuum water will boil at around 38 C.

After two thirds or more of the water and HCl was distilled off, a yellow liquid started coming over. I had to boil it down dry as a bone and replentish it with water once to get it to all come off. Nice to know I'm rid of the Ru and Os though. The diammonia oxychlorides dont smell (not that volatile) and are not toxic to be near (I don't mean touch with skin or ingest of course).

So now that I've got my dirty leach salts boiled dry, I'm just gonna go ahead and incinerate as is. Then wash out the base metals and afterwards see what will stay on after boiling AR. I know, if it starts to go from bright orange to brown, that means the Pd (bright orange) is all disolved and I'm biting into the Rh already (will keep a close eye on the color).

Now I'm also figuring out how to get that Os and Ru out of the water and HCl. I neutralized some with Sodium Hydroxide and added a bit of HCl-dissolved zinc. So does the milk colored mass at the bottom contain the Ru and Os? 

Some of the boil off wasn't very concentrated at all, I guess I'll have to concentrate it by redistilling and carefully watch the color that is coming over? Or will zinc cause the Os and Rh to drop out, even if the solution is dilute? 

I guess I could go ahead and neutralized/alkalinize it with Potassium Hydroxide and then add enough alchohol to make the solution 5% alchohol for black grit of Ru and Os dioxide precipitation.

Any ideas? Tips?

Thanks in advance,
Paul

P.S. pictures coming after I figure out how to edit their size


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## lazylightning (May 27, 2008)

Hi, I tried to add photos but it says the size must be no more than 800x600 pixels. I even made them 700x 525 and I still get that same message.


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## Scott2357 (May 27, 2008)

Try making it 400 pixels on the longest side using a free program called Irfanview.


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## Lino1406 (May 28, 2008)

How? And if you incinerate, will it not
sublime? last, any precipitate of spongy 
precious metal is black.


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## Lino1406 (May 28, 2008)

black, except gold which is chocolate


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## lazylightning (May 28, 2008)

Lino1406 said:


> How? And if you incinerate, will it not
> sublime? last, any precipitate of spongy
> precious metal is black.



Sorry, I don't know what you mean by incinerating may cause it to sublime or what consequences that will incur. As I've come to understand, the oxidant is boiled off repeatedly(with rehydration of 2-5% HCl) to make sure the oxidant is gone. That method of removing the oxidant is usually performed by boiling it down to a syrup. I had to bring mine down to bone dry to get all those re-dripping drops of syrupy yet volatile oxychlorides of Ru and Os to exit the reactor. Besides when it started getting lower, the stuff was drying onto the sides of the round bottom flask and it was still quite watery in consistency in the middle. No way to get a syrup here. 
Maybe that is another effect of the ammonia chloride added to turn the Ru and Os into volatile oxychlorides to be distilled off.

So what will happen now that the oxidant is gone, and it is mostly a dry powder. Why can I not just incinerate it and then wash out the base metals? It's the first time I've heard anything negative about incinerating. Especially now that the Os and Ru are gone from it.

I have not heard that all pgm precipitants are black. What about the crystals of Pd and or Pt that appear after adding ammonia chloride to a properly de-oxidized solution, for example? I know that a 25% solution of potassium hydroxide is used to capture the OsO4 and/or RuO4 out of a stream of air that bubbles through it. Later alchohol is added so as to bring the percent to 5% which is claimed to be the most optimal percent for precipitating the OS and Ru out of the alkaline solution. It precipitates as a black color. So if I just concentrate the solution with a carefully watched partial boildown and then alkalinize it (or partially alkalinize it before boil down), then it seems I should be able to make it drop out with the proper amount of alchohol.


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## lazylightning (May 28, 2008)

Here are the photos of the distilling process. Vacuum pump is an old American Science surplus rebuild deal, not very strong at all, but quite enough to make it work. Couldn't imagine it without the vacuum pump. The pump has to be turned on and off at times to get an optimal effect. Sometimes the spiral in the refrigerator gets full of liquid that slows the process, so I release some vacuum from the side of the reactor by carefully pulling the smallest plug, causing the liquid to clear the refridge spiral and flow quickly into the collection flask. After a minute the vacuum is back up and it's boiling again.


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## lazylightning (May 28, 2008)

sry, photos are in reverse order. but now I know how. Urah!


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