# What's The Color Of Solution After Adding SMB To Drop Pd



## MrMylar (Jun 25, 2015)

Hello,

I was wondering what would be the color of the solution after dissolving Palladium with diluted nitric acid and then adding sodium metabisulfote? I anticipate the solution itself would be almost a clear color before the addition of the smb, but not sure what to look for when adding the smb. Do I add it in the same amount as dropping gold, meaning more or less of it? I do know to check with a stannous.

Thanks!


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## solar_plasma (Jun 25, 2015)

First I wondered about your question: SMB, Pd, ?? But yes you are right according to this chart: http://www.goldrefiningforum.com/phpBB3/viewtopic.php?f=49&t=6026&p=87562#p87562

SMB to precipitate from sulfate or nitrate solution. There seems not to be written a lot about this possibility. I hope this will change in this thread. Thanks for asking!

Btw. theoretically you need about 1,3 times as much smb as you would use for Au+++ (at least according to my modest stoichiometry) based on Au's and Pd's molar weight and their valence.


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## kurtak (Jun 26, 2015)

solar_plasma said:


> But yes you are right according to this chart: http://www.goldrefiningforum.com/phpBB3/viewtopic.php?f=49&t=6026&p=87562#p87562



That chart is "somewhat" misleading !

Dropping Pd from a nitrate solution with anything other then DMG is not a simple task --- Ph adjustment is needed for other precipitants to work

For SMB to work you need to adjust the Ph to near neutral - if you use NaOH (or a hydroxide) to adjust the PH & other metals like silver or copper are involved those metals will "start" to precip as there hydroxides --- as discussed here :arrow: http://goldrefiningforum.com/phpBB3/viewtopic.php?f=51&t=9058&p=226091&hilit=hydroxides#p226025 (read from the post this link goes to on down for next 7 or 8 post) 

Another why to precip Pd from a nitrate solution is to do so as a diammine (salt) which uses ammonia to adjust the Ph to basic & then HCl to re-acidify to drop the Pd as the diammine salt --- whether this method is an option depends on what other metals may be in solution - If memory serves me right I don't believe it is an option if silver is involved --- if copper &/or nickel are involved this method (I believe) works as the Cu/Ni forms an imine which does not precip - to remove the Cu/Ni from the waste requires Ph adjustment again & the addition of sodium hypochlorite (sodium hypochlorite is needed to break the hydrogen bond before the Cu/Ni will precip)

I believe I have that right - Lou can correct me if I am wrong

DMG is the easiest why to drop Pd from a nitrate solution - its "selective" & does not involve any other chemistry in the precip step - it still needs reduction though

Prepare your DMG with NaOH - do not prepare it with any alcohol's (as suggested by some) alcohol's introduced to acidic metal solutions can create fulminates of metals which are very pressure sensitive explosives - silver fulminate in particular which is so pressure sensitive it can explode under its own weight & when still wet

Kurt


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## MrMylar (Jun 28, 2015)

Thanks for the replies.

I do have some DMG, but I never used it yet. I will need to read up on how much I should use. I have a 3-4oz squeeze bottle. It may be a 2oz bottle. It says 3% and it also says for testing for Pd/Pt. Would that be the correct DMG?

Thanks again for the replies.


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## kurtak (Jun 29, 2015)

MrMylar said:


> Thanks for the replies.
> 
> I do have some DMG, but I never used it yet. I will need to read up on how much I should use. I have a 3-4oz squeeze bottle. It may be a 2oz bottle. It says 3% and it also says for testing for Pd/Pt. Would that be the correct DMG?
> 
> Thanks again for the replies.



First - DMG does not test for Pt - it is used to test for Pd in an acidic solution & Ni in a basic solution (made basic with ammonia) & is "selective" for those metals which is why it is used for testing for Pd (read Hokes)

Now - it takes about 2.5 grams of DMG to precip 1 gram Pd --- if your test solution is 3% - that means it has 3 grams DMG dissolved in 100 ml water so 100 ml of the test solution would drop just a bit over 1 gram Pd (3oz = 90 ml)

To prepare DMG from its powder form so it can be used for testing &/or used to precip Pd from a solution you need to dissolve 4 grams NaOH in 100 ml water - heat - then add 5.81 grams DMG - which means 100 ml of prepared DMG will drop a bit more then 2 grams Pd

What is the sources of your Pd nitrate solution ? --- in other words - what other metals are in the solution (determined by the original sources of the feed stock &/or material dissolved/leached)

In other words - you (we) can't determine the best method to recover the Pd from the solution with out knowing what is in solution - DMG may (or may not) be the best way to go

Kurt


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## MrMylar (Jun 29, 2015)

Thanks for your reply kurtak.

I also stand corrected, my DMG says Pd/NI Spot test. Not sure why I said Pt. Sorry about that one. But mine is in solution form and not a powder.

My source material is from my waste AR solution. I already dissolved my copper scraps in it and I filtered the solution and what I had left was a large amount (approximately 150mL) of grey sludge. After rinsing the powder I used diluted nitric acid and it did fume some. I haven't filtered that solution yet, but I was going to see if anything will drop from the solution and then after rinsing the powder real good, I was going to dry it, then try to melt it, then after that, take the melted piece and dissolve it (after acid testing it first) and then try to separate the metals.

Is that approach good?

I was thinking about after rinsing the powder to put it in some HCL and see if it would dissolve any lead, if present, and then rinse well, and then do AR on the powder.

The materials in which the waste AR from included ceramic and fiber cpu's, IC chips, flatpacks and n/s chips, gold filled jewelry for the most part. But all the solution was AR solution waste.


Thanks


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## kurtak (Jun 30, 2015)

Before I post more lets find out if in fact you have Pd in solution - you have the DMG test solution for doing so --- why haven't you used it ? (or have you & just haven't told us so)

its easy - put a bit of solution in a spot plate, test tube, or small beaker - ad a drop of DMG test solution - if you get a fluffy "yellow" precipitate you have Pd

after doing the DMG test - test with stannous to see if &/or what else may have gone into solution

Because this came from AR cemented with copper there should be no silver so I would consider dropping any Pd as its diammine (salt) --- do a search using diammine as your search word - you will find plenty of info 

You still then have to do a reduction of the salt to metal (whether DMG or diammine drop) 

How do you intend to melt - MAPP gas torch won't do it if its Pd (or PGMs)



> I was thinking about after rinsing the powder to put it in some HCL and see if it would dissolve any lead



There should not be any lead if you used sulfuric to drop lead sulfate in the original AR &/or used sulfamic to de-Nox

Kurt


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