# droping PGM using AL



## pgm (Nov 6, 2010)

Hello everyone...

can anyone tell me when can you drop out PGM using aluminum?

and is there such a thing as -1 PH?

thanks

Adam


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## Lou (Nov 6, 2010)

I'd avoid the use of aluminum if at all possible. It works but if the pH gets too high (i.e. >1 or 2), aluminum oxide/hydroxide will precipitate and make your life miserable. If that does happen, you would have to boil with sodium hydroxide to remove the alumina.


And yes, there is such a thing as -1 pH and far below!

Lou


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## pgm (Nov 6, 2010)

thankyou for the update....i did this with a friend and we got a really good result and the turn around time was like 32 hours. how do i get -1PH, how would i measure this.

the result gave us 95.1% Pt and 4.9 Rh. i like the result and would like to try doing this again but it is not happening now for some reason.


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## pgm (Nov 6, 2010)

Lou said:


> I'd avoid the use of aluminum if at all possible. It works but if the pH gets too high (i.e. >1 or 2), aluminum oxide/hydroxide will precipitate and make your life miserable. If that does happen, you would have to boil with sodium hydroxide to remove the alumina.
> 
> 
> And yes, there is such a thing as -1 pH and far below!
> ...



if the aluminum does drop out then could i not add some HCL (36%) to dessolve the aluminum, this should leave the Pgm behind...


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## pgm (Nov 6, 2010)

do you have a step by step guide on what stage the ph should be from start to finish....i two i have seen are -1ph and ph 4 when filtering


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## Lou (Nov 7, 2010)

Keep the pH below 2.5.

Straight 12M HCl is below -1 in pH if I recall, and concentrated sulfuric is -4 or so.

Anyway, the precipitate is hard to dissolve if it does form, so avoid forming it!


Lou


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## pgm (Nov 7, 2010)

Lou said:


> Keep the pH below 2.5.
> 
> Straight 12M HCl is below -1 in pH if I recall, and concentrated sulfuric is -4 or so.
> 
> ...



Again thankyou for your the feedback 

it is making more sense to me now. we heated up the HCL to boiling and then added the cat con, then added the nitric

You said "Straight 12M HCL" does this mean HCL has to be lab grade (12%) 
what does this mean? i dont understand the termonology here


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## Lou (Nov 7, 2010)

12M ~ 37% w/v


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## pgm (Nov 8, 2010)

Lou said:


> 12M ~ 37% w/v



THANKS again...where would i go to find out more on this type of symbols...new to chemistry but i am moving really quick, learning the hard way making 101 mistakes. 

i am reading hooks but these symbols are not there.

thanks again


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## Lou (Nov 8, 2010)

http://chemistry.about.com/od/workedchemistryproblems/a/molarityexampl1.htm


Just a primer. Any questions, PM me and I'll explain further.


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## pgm (Nov 8, 2010)

thankyou again and i will pm if i get stuck


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## samuel-a (Nov 8, 2010)

pgm

Aldough, using Zinc is the best choice to drop PGM's out of solution, since i didn't had any, i used aluminum, and quite successfully i might add...

Since cat leaching involves big volumes of solution, the risk of adding too much aluminum is low, you just add aluminum pieces until no more black PGM's powder forms on the aluminum chunk, as well as noticing the color of the solution, once it's clear, you can tell that your solution is free of PGM's.
you should test it anyway with stnnous chloride just to make sure before you filter and discard it.


When i convert AgCl to elemental silver i usually leave it over night, covering the AgCl with a 10% sulfuric solution and throw in Al rod.
the day after, the beaker is full with alumina mixed with the silver.

this i solve by almost 10 water washs and 2 water boiling, sounds like alot of work, but it's really not that much...
the silver melts fine btw..

good luck


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## pgm (Nov 9, 2010)

samuel-a said:


> pgm
> 
> Aldough, using Zinc is the best choice to drop PGM's out of solution, since i didn't had any, i used aluminum, and quite successfully i might add...
> 
> ...



Thanks for the update...i have alot of aluminum....i am doing this on a large scale....should be doing 20kg for the next test..... 200kg to play with...


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## HAuCl4 (Nov 9, 2010)

Can one *easily* inquart with alumimium or zinc or is it too much hassle?.


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## Barren Realms 007 (Nov 9, 2010)

HAuCl4 said:


> Can one *easily* inquart with alumimium or zinc or is it too much hassle?.



It would not be a good idea to inquirt with a metal that would drop your gold out of solution. Both of these metals can have a violent reaction to the acids.


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## HAuCl4 (Nov 9, 2010)

Do you see how your response does not make sense?. Gold or PGMs aren't supposed to "go in solution" after inquartation. They are to stay as pulverized metals for the next treatment. :shock:

"violent" has degrees too, depending on the concentration of the acids.

I can see how an aluminium or zinc inquart could become too fast/explosive if exposed to pure nitric acid, or maybe passivated in the case of aluminium and not reacting at all, so let's see what Lou says. :idea: 

HCL and zinc would go fast too. :shock:


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## T3sl4 (Nov 9, 2010)

HCl (31.45%, no nitrate) dissolves bulk zinc at a reasonable rate. I wouldn't want to use finely granulated or powered zinc.

Tim


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## Barren Realms 007 (Nov 9, 2010)

HAuCl4 said:


> Do you see how your response does not make sense?. Gold or PGMs aren't supposed to "go in solution" after inquartation. They are to stay as pulverized metals for the next treatment. :shock:
> 
> "violent" has degrees too, depending on the concentration of the acids.
> 
> ...



I have been on the forum for over 1-1/2 years and have had to work with these chemicals for over 20 years. I knew before I even came on here what basic metals you should use caution before mixing them with the chemicals used here on the forum.

You are correct in that my response didn't make sense after I look back at it. It was right in line with your question you asked. In the time I have been on here you are the first person I have seen that I can remember that has asked the question you asked.

You are constantly asking questions that are off the wall and when it is suggested that they are not worth you useing the procedures you ask about you continue to harp on the process. Your comments are going to be taken out of context some time by someone that dosen't know what they are doing and you are going to get someone hurt. But it will not be me...

You are the individual selling your services as a consultant, not I. I tell you what show some proof of what you have produced with the procedures tought on the forum and then you will be taken more seriously.

I knew I should not have comented on your question. And it will be the last one of your questions I respond too.


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## HAuCl4 (Nov 9, 2010)

Whatever makes you feel fine brother barren. 

I have nothing to prove to you or anyone, and my questions stand as genuine. 

And for your information, lazersteve posted a book with procedures for refining PGMs that speak of alloying with aluminium. It looked weird to me, but there you go. 

Check it out and maybe you'll learn something as I did!. 8)

Patience is a virtue!.


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## pgm (Nov 9, 2010)

HAuCl4 said:


> Whatever makes you feel fine brother barren.
> 
> I have nothing to prove to you or anyone, and my questions stand as genuine.
> 
> ...



Hi Sorry to get in middle of things can i get the link to this book steve has posted?.

I can confirm at this stage i have done a test with aluminum and i did drop pgm with my first go, i had this confirmed by the assay office in sheffield and yes it is a violent reaction have to be careful not to add too much as it will boil over, 

i am doing so many experiment i have to learn to post the videos here so you can check what i am saying. i think this will be helpful to other users on the forum, i will be learning and so will everyone else......

i have been on the forum less then both of you, just joined but i have found i am learning at a quicker speed due to having all the equipment and chemicals and doing regular testing..once the test is finished i will be posting pictures...thankyou for joining in with my question


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## HAuCl4 (Nov 9, 2010)

Here it is PGM. It is not very detailed, so take time to understand well and even more time if you plan on doing it!. There are several processes to do the same type of refining. In one of them they speak of alloying with aluminium to facilitate the dissolving...



lazersteve said:


> Here's a nice flowchart from a book that include Sx for many precious metals:
> 
> Solvent Extraction Scheme for Ore
> 
> ...


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## pgm (Nov 9, 2010)

HAuCl4 said:


> Here it is PGM. It is not very detailed, so take time to understand well and even more time if you plan on doing it!. There are several processes to do the same type of refining. In one of them they speak of alloying with aluminium to facilitate the dissolving...
> 
> 
> 
> ...



Thankyou for the link....................every little helps


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## PreciousMexpert (Jan 15, 2011)

If I am not wrong Harold used aluminum to drop silver 
Is there a link to this somewhere


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## Oz (Jan 15, 2011)

PreciousMexpert said:


> If I am not wrong Harold used aluminum to drop silver


I highly doubt it.


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## butcher (Jan 15, 2011)

maybe you are confusing converting silver as chloride to metal powder with aluminum.

aluminum in some acids can get pretty gooey like slime.


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## pgm (Jan 15, 2011)

butcher said:


> maybe you are confusing converting silver as chloride to metal powder with aluminum.
> 
> aluminum in some acids can get pretty gooey like slime.



butcher you spot on when you say it gets pretty gooey.....better using zinc, which is safer option and no need to mess with ph levels.


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## Harold_V (Jan 16, 2011)

PreciousMexpert said:


> If I am not wrong Harold used aluminum to drop silver
> Is there a link to this somewhere


Absolutely not! That cements copper, too, which would defeat the purpose. 

Note that I do not (ever) use the word "drop"---I don't like it ---especially in this case, where cementation is the word that should be being used, to avoid confusion. 

I did use aluminum for converting silver chloride to elemental silver, however, but that's not free of problems. I used it because I had it and do not endorse the idea. There are better ways. 

Harold


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