# precipitating all catalytic pgm's from an ar leach



## Anonymous (May 15, 2008)

hey all, i've got a quick question for you. after leaching the substrate in an ar bath for a few hours, and having have tested positive for platinum, palladium, and rhodium, what would be the best method to drop all the pgm's at once. i have no need to separate them but i would like the most efficient way to drop them out.... based on everyones experience.

i can spend all night reading this forum until information overload!
thanks a lot, you guys rock!


-david


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## Lou (May 15, 2008)

Zinc.

Preferably without nitric.


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## jaun (May 17, 2008)

Lou, will iron also work? It is cheaper and much more available.


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## Lou (May 17, 2008)

yes, but it is more difficult to wash out.


Easier to spend more to save time.


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## jaun (May 17, 2008)

How do you wash out the iron, with water and HCL. I have some blacks I cemented out with iron nails.


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## Lou (May 17, 2008)

Water and HCl would definitely work. Just an added step in my eyes. I dislike washing things with HCl (I use a pump, no aspirator, and I sometimes forget to put the output to the hood! :-/ )


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## Anonymous (Jun 8, 2008)

i tried zinc powder and the solution seemed to react quite violently with it, yet there was no precipitate. is there a certain amount i have to add or something i am missing here?


-david


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## Irons (Jun 8, 2008)

slaveforthewave said:


> i tried zinc powder and the solution seemed to react quite violently with it, yet there was no precipitate. is there a certain amount i have to add or something i am missing here?
> 
> 
> -david



You have to neutralize the solution first.


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## Lou (Jun 8, 2008)

Actually Irons, a wee bit of acid really helps the reduction.


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## lazersteve (Jun 8, 2008)

I've had good results from solutions of lower pH also. 

I've done several zinc precipitations and never once neutralized any of the acid. I typically evaporate all my solutions and rehydrate with HCl. I use zinc to clean up any solutions where residual PGMs were left behind from the ammonium chloride and sodium chlorate reactions. So this may explain why the pH of my solutions is in the correct range. I've never tested the pH before hand to be certain, but I'm assuming since I'm working in acidic solutions that the filtrates are also acidic to a degree.

I've also used zinc to cleanup my stock pot without adjusting the pH. It may be interesting to know at exactly what pH zinc will and won't work.

One last note, if your solution doesn't contain any dissolved metals below zinc in the activity series, you won't get any black precipitates either.

Steve


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## Irons (Jun 8, 2008)

Lou said:


> Actually Irons, a wee bit of acid really helps the reduction.



The wee bit is the key. Any excess just eats up Zinc. 8)


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## goldsilverpro (Jun 8, 2008)

I've found this to be the case with all cementation processes. You need a wee bit of free acid. Often, when the acid was totally spent, I have found myself needing a wee bit of acid. To cement something, you have to first dissolve something else. To do this, you need a bit of free acid.


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## markqf1 (Jun 9, 2008)

A wee bit without nitric.
What is a wee bit?
It must have a ph number,... right?
There has to be some definitive info somewhere.

Mark


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## Platdigger (Jun 10, 2008)

I have some info "somewhere" that states at least for cementing gold out of solution with zinc, that the ph window is actually quite narow.

If I can find it I will post it, but I believe it was saying that gold quits coming out of solution with zinc at around the ph of about 5.5.

In other words, if you start out at a ph of about say 3, and end up at a ph of 6 or 7, if you didn't pass through the ph window too quickly, you would have dropped your gold.

The zinc disolving into solution, raising the ph.

With the platinums on the other hand......I am not sure.
Randy


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## Platdigger (Jun 10, 2008)

One way to insure that you don't raise the ph too quickly, is to use chunks of zinc instead of powder.
Randy


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## Lou (Jun 10, 2008)

Fine Mark. pH is 2-4 ideally.


Yawn (damn insomnia!).


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## Irons (Jun 10, 2008)

Platdigger said:


> I have some info "somewhere" that states at least for cementing gold out of solution with zinc, that the ph window is actually quite narow.
> 
> If I can find it I will post it, but I believe it was saying that gold quits coming out of solution with zinc at around the ph of about 5.5.
> 
> ...




5.5 isn't very acidic. A Ph of 5 is 1x 10 to the minus 5 moles of hydrogen ions per liter.


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## markqf1 (Jun 10, 2008)

Mmmm,... that sounds real technical!
Thanks Lou.
I have invested in a good ph tester!

Mark


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## markqf1 (Jun 20, 2008)

Sounds good Randy,
But shouldn't zinc be used only in the final phase of cleaning up the pgm solutions?
Selective precipitants then zinc?
Ph seems to definitley be a factor.

Mark


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## Anonymous (Jun 23, 2008)

i certainly hope not mark, the idea behind it was to precipitate them all at the same time into one sludge...

i have a means to sell them as a whole, and it seems like it is less productive to waste time with different chemicals and test is i can leach them and drop them all together...


so the general consensus is to use a solid piece of zinc instead of powder and make sure my ph is between 2 and 4 by means of neutralization (i assume through the evaporation technique)?


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## Froggy (Jun 24, 2008)

I bought an orp and ph meter, I couldnt believe the solution that action mining sells, would up being .79 ph!! hot,hot,hot!!!,, i tried to use zinc but it took a boatload!


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## markqf1 (Jun 27, 2008)

Hey Frog,
You ever figure out the chemical makeup of the cls26p?

Mark


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## cerise (Jul 1, 2008)

I started my Journey by using aqua rega from I shore and they say to precip using aluminum foil.Ive boiled 6 converters and precipitated the solution with aluminum foil and I have about an ounce of gray mud .
I Shore hope im doing it right.LOL any way i havent went any further with that mud because ima little confused as what to do next.So i went on to do some of the gold i have been collecting .This is where i ran into problems.
First of all i dissolved chips with boards and i didnt break the boards down like Steve shows in his vids.So I have dissolved about 100 chips and about 10 lbs of scap boards in this solution and the AR seems to be full and its not dissolving anymore.I let the solution sit a night then the next morn i used Ishore's so called storm precipitant untill it quit fizzing and let sit till the next day again and came back to dark amber solution with some gray mud and red mud but only a little brown mud.It seems like it wasnt done preciping I did a test and it shows gold ,but i cant imagine it takes 2 days to precip.Can i start over and what do i do boil all the water down ?I think it was easier doing the honeycombs.


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## Noxx (Jul 1, 2008)

Cerise, you can't throw an entire board into AR, there is too little gold. All the acid will eat the other metals. Don't forget that gold is the last one to dissolve.


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## cerise (Jul 1, 2008)

Thanks for that Noxx.
This place is the best.Your all so helpful.


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## Froggy (Jul 3, 2008)

I believe it to be nitric, simple and sweet?


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## Platdigger (Jul 3, 2008)

Could be huh....it calls for hcl to be added......
Randy


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## markqf1 (Jul 3, 2008)

Well it might be but, it sure didn't work like the " real stuff" I have now.
I've still got about 9 lbs. of it if anybody needs some.  

Mark


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## cerise (Jul 11, 2008)

Mark if its real nitric ,yes ill but i and what is nitric made from ?


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## markqf1 (Jul 11, 2008)

Not sure what it is.
If any competent individual wants to experiment with it , I have a plenty.
Action mining sells it and they will sell you the formula.  

Mark


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## lmschers (Dec 10, 2010)

cerise said:


> I started my Journey by using aqua rega from I shore and they say to precip using aluminum foil.Ive boiled 6 converters and precipitated the solution with aluminum foil and I have about an ounce of gray mud .
> I Shore hope im doing it right.LOL any way i havent went any further with that mud because ima little confused as what to do next.So i went on to do some of the gold i have been collecting .This is where i ran into problems.
> First of all i dissolved chips with boards and i didnt break the boards down like Steve shows in his vids.So I have dissolved about 100 chips and about 10 lbs of scap boards in this solution and the AR seems to be full and its not dissolving anymore.I let the solution sit a night then the next morn i used Ishore's so called storm precipitant untill it quit fizzing and let sit till the next day again and came back to dark amber solution with some gray mud and red mud but only a little brown mud.It seems like it wasnt done preciping I did a test and it shows gold ,but i cant imagine it takes 2 days to precip.Can i start over and what do i do boil all the water down ?I think it was easier doing the honeycombs.




have you tried cooking that Al precipitate with sodium hydroxide? 
they react well together. don't know what it would give you.

watch this:
http://www.youtube.com/user/periodicvideos#p/u/4/WnPrtYUKke8

the periodic videos are nothing short of wonderful.


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