# adding lime water in the dark to the pgm leach



## lazylightning (May 11, 2008)

Hi,

I've read the history of platinum ruble minting in Russia in the 19th century and found some interesting references. 
So they had a terrible time getting iron out of the platinum (and iridium too). Some of the rubles had enough iron in them to be picked up by a magnet. Decades later they were recalled.
Later they found a process that caused everything to drop out of dirty solution except for the platinum which stayed in solution. They added lime water in the dark. 
So does anyone here know about this?


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## Lino1406 (May 13, 2008)

How it was received?


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## lazylightning (May 14, 2008)

Has anyone here ever used it? What concentration of calcium hydroxide in the water? How much to add? After all, it has to be done in the dark, it's impossible to see what's going on. 

So it sounds like a titration drop to me, but maybe not. There may be a limit to the ph level that you can go up to. It may be a little more complicated than described at first glance.

Good to know any and every possible method for seperating one pgm from another or group of others. Every move needs to be thought out like in a chess game and any new possible move might come in handy.


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## lazylightning (May 14, 2008)

I couldn't figure out how to upload any files to this site, so I just copied the text from a pdf file. It's long and out of format, but may be of interest to someone. The reference to the limewater addition in the dark is in it.

Snip - lazersteve

Document attached as pdf. lazersteve


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## Irons (May 14, 2008)

A mid 19th Century reference on the precipitation of Palladium using alkaline Carbonates. Right-hand column towards the bottom of the page under Palladium.

http://tinyurl.com/6o5lks


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## lazersteve (May 14, 2008)

I took the liberty to convert the info to pdf and attach it to your post, I hope you don't mind, but the long post was throwing the formatting of the thread way off.:wink: 

Steve


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## lazylightning (May 14, 2008)

Irons said:


> A mid 19th Century reference on the precipitation of Palladium using alkaline Carbonates. Right-hand column towards the bottom of the page under Palladium.
> 
> http://tinyurl.com/6o5lks



Funny! Lime water is all over that page, but in connection to other words near Palladium and it's mentioned again in association with Pd as alkaline carbonates. Is calcium hydroxide an alkaline carbonate or alkaline calciumate? ;D


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## lazylightning (May 14, 2008)

lazersteve said:


> I took the liberty to convert the info to pdf and attach it to your post, I hope you don't mind, but the long post was throwing the formatting of the thread way off.:wink:
> 
> Steve



Thanks very much! 

I'd have done that too, but I don't know how


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## lazylightning (May 14, 2008)

I suppose they may have been talking about a solution that was already mostly freed of iron. Although the point of that case was getting platinum more pure and with less iron. So I guess it was done with iron in the solution. 

Strange though, when I re-read the text more carefully it seems to imply that the level of iridium as a contaminant became a bit higher later after they started using this process. I guess that was more acceptable for them if the iron could be kept out. Platinum Rubles jumping to a magnet must have been embarassing for that general responsible for the production. No promotions and medals for bad work here.

As the writer mentioned the task was to produce it at an economical level, so I guess they weren't going to go into re-dissolving and re-precipitating extra times for more pure stuff. Lot's of extra time, labor and material.

I like the idea of dropping it all incinerating and starting fresh with washes to get rid of base metals first. This way it would be possible to drop everything and drop the platinum seperately in another ph. Then incinerate the main drop and the Pt drop seperately. Redissolving that Pt and then precipitating again might make it purer, a step ahead. Anyway with the Pt out of the way the main batch would be a bit more manageable.


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## Lino1406 (May 14, 2008)

Maybe,
lime water + biological activator + light = oxygen
" " + " " + dark = CO2 (?)


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## Irons (May 14, 2008)

lazylightning said:


> I suppose they may have been talking about a solution that was already mostly freed of iron. Although the point of that case was getting platinum more pure and with less iron. So I guess it was done with iron in the solution.
> 
> Strange though, when I re-read the text more carefully it seems to imply that the level of iridium as a contaminant became a bit higher later after they started using this process. I guess that was more acceptable for them if the iron could be kept out. Platinum Rubles jumping to a magnet must have been embarassing for that general responsible for the production. No promotions and medals for bad work here.
> 
> ...



Pure Platinum is quite soft but the small amount of Iridium would increase the wear resistance of the coins.


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## lazylightning (May 14, 2008)

> Pure Platinum is quite soft but the small amount of Iridium would increase the wear resistance of the coins.



Makes perfect sense. Maybe the increase of iridium became possible after they started getting rid of the extra iron. Perhaps they actually added it :O


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## Shecker (Aug 6, 2008)

Once I had a solution that I knew had gold and pgm's in it. I wanted to neutralize the acidity so I tried sodium carbonate. It foamed like crazy but settled down after a couple of hours. Then I found I had gold in solution and a pgm carbonate in the bottom of the bucket. I filtered out the pgm bearing carbonate product to facilitate gold recovery, then I got to wondering what I could do with the carbonate fraction. So I added HCl and after another two hours of foaming found a nice layer of metallic pgms in the bottom, very bright and shiny. I never used this more than once because of the foaming problem and the fact that the foam would run over my work shop floor.

Randy in Gunnison


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## Platdigger (Aug 6, 2008)

Hi Shecker, was this an AR solution?
Randy


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