Purifying Palladium Precipitated from Dirty Solutoins

Many times when Palladium is precipitated the solution contains base metals like iron, copper, and nickel. Like gold that is precipitated from a dirty solution, the resulting Palladium Ammonium Chloride will drag down metals from the dirty solution with the resulting brick red Palladium salt.

Here's a photo of such a precipitation:



and the resulting dry palladium salt:



Hoke describes a method of cleaning the dirty Pd salt using ammonium hydroxide( NH4OH). She mentions using aqua ammonia (28% concentration), but I have found that a 10% solution of ammonium hydroxide will work equally well.

The first step is to dissolve the dirty Pd salt in NH4OH. When the NH4OH is first added the Pd salt will turn to a orange flesh colored salt. As more ammonium hydroxide is added with stirring the flesh colored salt will dissolve into a nearly clear yellow tinted solution. Some solids may remain behind.

At this point allow the solution to sit for a least one hour or until no more of the solids will dissolve with a fresh dose NH4OH and stirring. Use only enough NH4OH to dissolve the flesh colored precipitate. Depending on the contaminating metal you may see various colored solids in the bottom of the beaker. Iron leaves brown fluffy residue, copper colors the solution slightly blue, tin leaves a white pasty material. Some of the other platinum sister metals will also leave colored solids behind. Typically these PGM salts will be red, orange, yellow, and possibly even drab green colored depending on the PGM and the contaminates in the solution.

Now the solution is filtered with a vacuum filter rig and rinsed with a small amount of ammonium hydroxide. The filtered solution should be nearly clear with a slight tint of yellow.

Here's a snapshot of the contaminates removed from the Pd salt in the first two photos:



Now that most of the impurities have been removed you can slowly add 32% HCl (muriatic acid) to the solution to precipitate the clean Pd salt. Add enough HCl to make the solution acidic. Add the HCl slowly as the solution will rapidly heat and may foam up. Allow the solution to set for at least one hour.

Here's the clean Pd salt precipitating:



Now vacuum filter the clean yellow Pd salt out of the solution and allow to dry. Test a drop of the solution with DMG to be certain all of the Pd has been removed.

Here's the filter of clean Pd salt:



You can repeat this process to further purify the Pd if you like.

The resulting yellow Pd salt is now converted to Pd sponge via your favorite method, then melted under a hydrogen flame if desired.

Steve

thanks steve this is very good information as....i am currently doing a test using your DVD...pic's are always helpful.

What Purity is the Pd When its dirty 30% 40% 50% or higher See i have a few refinery accounts in Canada and they will just pay for the content less 2% as long as the goods arent too low a content of Pd

The impurities typically amount to less than 5% of the total weight of the Pd at the highest levels of contamination. An average of 2% contamination by weight would be a good ball park estimate. I'll seen plenty of times when there was no measurable residue after the Pd salt was dissolved in NH4OH.

Steve

This is industry standard for palladium. Two iterations is usually more than sufficient for the worst cases.


Lou

I have a mud that I have used a series of process to get to. Now I beleive I'm down to the PGM's, but I need some help. My goal is to get this mud to a state where I can identify the metals postivly and get the value out without getting ripped off.
Here's what I did and have.
I started with a high grade ore concentrate, crushed to about face powder, added to a mixture of Ag and Pb acid, for the ionic exchange. Mixed with a base to neutralize, dropped out everything to a mud. I mixed in a recipe of flux I like, let it go tranquil at 1985 degrees and poured. The resulting bar was about 17% more that want I started with. After cupling the lead bar to buttons I used acid and DI to drop out the Au. I then dropped out the Ag and mixed it with a flux and poured Ag bars. The balance of the solution I used iron nails to part out the Cu. The balanced a green colored solution, I nutralized that and have a black mud that I belive are the PGMs.
What do I do now? Is it marketable the way it is? Or do I have to part out all the Pt-Sisters?
If so who's first and how?
Is the Cu powder and crystals marketable? if so where, and I know what to do with the Ag & Au, but would like to get a better percentage?
Thanks, DanO

Five-O-DanO said:

I have a mud that I have used a series of process to get to. Now I beleive I'm down to the PGM's, but I need some help. My goal is to get this mud to a state where I can identify the metals postivly and get the value out without getting ripped off.
Here's what I did and have.
I started with a high grade ore concentrate, crushed to about face powder, added to a mixture of Ag and Pb acid, for the ionic exchange. Mixed with a base to neutralize, dropped out everything to a mud. I mixed in a recipe of flux I like, let it go tranquil at 1985 degrees and poured. The resulting bar was about 17% more that want I started with. After cupling the lead bar to buttons I used acid and DI to drop out the Au. I then dropped out the Ag and mixed it with a flux and poured Ag bars. The balance of the solution I used iron nails to part out the Cu. The balanced a green colored solution, I nutralized that and have a black mud that I belive are the PGMs.
What do I do now? Is it marketable the way it is? Or do I have to part out all the Pt-Sisters?
If so who's first and how?
Is the Cu powder and crystals marketable? if so where, and I know what to do with the Ag & Au, but would like to get a better percentage?
Thanks, DanO

Click to expand...

Hi

and welcome to the forum....first post ha...have you read Hoks....well this is what everyone will tell you to do first..

ok
Pd is the first to come out of the black mud
pt is next and then Rd is left

please read hoks you will understand it.

Steve

Please help. I think I may have really boo booed.

I have a large batch of Pd salts that were precipitated from HCL-Cl-Peroxide solution using Ammonia Chloride and then simmer close to boiling and add Sodium Chlorate/ Calcium Hypochlorite method.

This produced nice big brick red crystals which I knew were slightly contaminated with other salts due to the source of the Pd. So I started to do the Pd purifying procedure you listed here using NH4OH to redisolve the crystals.

This went just as you stated and I had a nice light yellow colored solution with all of the Pd sodium Chlorate precipt disolved in the NA4OH solution and only a small amount of contaminate stuff on the bottom. Then I messed up. When I went to rinse the last set of Pd crystals from their filter into the NH4OH beaker I accidently grabbed the wrong spray bottle and rinsed the crystals into the beaker with Ammonia Chloride solution instead of NA4OH solution. Now my solution instead of being light yellow is a medium brick red color and there is a lot of light tan/white colored precipt floating around in it.
Also, I have an excess of Distilled H2O in the solution so Iwas trying to simmer it down to eliminate the extra H2O before filtering and adding the HCL to precipitate the Pd again.

I am thinking that the precipt I see floating around is probably Nacl that formed as a combination of the NA4OH and the Ammonia Chloride or some other contaminate.

If so, did I ruin this batch and need to start all over.

What do you suggest?

I am thinking to:

A. Simmer the solution down slowly, filter it, and then add more NA4oh to redisolve the PD again.

B. Then refilter and add the HCL to precipitate the Pd.

As a secondary thought I should probably try to redisolve the precipitant that is left in the filter from A. above with NA4oh again as well just to see if any will go into solution and then filter this again and add HCL to precipitate any Pd as well.

The precipts that are left from this could then be redisolved into HCL and try a Ammonia Chloride /Sodium Chlorate precipitation again to make sure that I do not miss anything.

Sorry for the rambling just thinking this through as I am typing.

Any suggestions will be gratefully appreciated.

Does what I said above make sense to fix this OOPS?

What would you suggest.

Thanks
Ron

rhwhite67 said:

Steve

Please help. I think I may have really boo booed.

I have a large batch of Pd salts that were precipitated from HCL-Cl-Peroxide solution using Ammonia Chloride and then simmer close to boiling and add Sodium Chlorate/ Calcium Hypochlorite method.

This produced nice big brick red crystals which I knew were slightly contaminated with other salts due to the source of the Pd. So I started to do the Pd purifying procedure you listed here using NH4OH to redisolve the crystals.

This went just as you stated and I had a nice light yellow colored solution with all of the Pd sodium Chlorate precipt disolved in the NA4OH solution and only a small amount of contaminate stuff on the bottom. Then I messed up. When I went to rinse the last set of Pd crystals from their filter into the NH4OH beaker I accidently grabbed the wrong spray bottle and rinsed the crystals into the beaker with Ammonia Chloride solution instead of NA4OH solution. Now my solution instead of being light yellow is a medium brick red color and there is a lot of light tan/white colored precipt floating around in it.
Also, I have an excess of Distilled H2O in the solution so Iwas trying to simmer it down to eliminate the extra H2O before filtering and adding the HCL to precipitate the Pd again.

I am thinking that the precipt I see floating around is probably Nacl that formed as a combination of the NA4OH and the Ammonia Chloride or some other contaminate.

If so, did I ruin this batch and need to start all over.

What do you suggest?

I am thinking to:

A. Simmer the solution down slowly, filter it, and then add more NA4oh to redisolve the PD again.

B. Then refilter and add the HCL to precipitate the Pd.

As a secondary thought I should probably try to redisolve the precipitant that is left in the filter from A. above with NA4oh again as well just to see if any will go into solution and then filter this again and add HCL to precipitate any Pd as well.

The precipts that are left from this could then be redisolved into HCL and try a Ammonia Chloride /Sodium Chlorate precipitation again to make sure that I do not miss anything.

Sorry for the rambling just thinking this through as I am typing.

Any suggestions will be gratefully appreciated.

Does what I said above make sense to fix this OOPS?

What would you suggest.

Thanks
Ron

Click to expand...

hi

i an't steve, but you might as well start again this would be better at this stage i think...

It seems like you tried initially to skip steps.


My advice: use zinc to cement out the palladium and send it out to a refiner. If you don't have that much and just want to have it pure, cement it out with zinc, add hydrochloric acid and then slow additions of peroxide until it's all dissolved. Technically, you don't even need sodium chlorate if you have extra peroxide (which means free chlorine) present in the solution. I prefer to do this cold rather than hot!


Doing it that way means less chlorate is needed.


You'll notice that my salt is much more red than Steve's and that I'm doing it from a far higher concentration solution. I was starting from already pure palladium that was stuck in crucibles (I was illustrating a way to reclaim it).

PGM and Lou
Thank you for your response.

I simmered as mentioned and then let the solution set for several hours. The floculant/precipt started out as a white/yellowish color and slowly turned a brick red color and when I filtered the solution to remove it the solution was the light yellow color that Steve talked about. Testded the solution with DMG and positive for Pd. However when I added the HCL to precipitate it does not want to precipitate so I am following Lou's suggestion of the zinc except that i have no zinc available at the moment so am substituting Tin which is lower in the electromotive series and readily available at Walmart in their new eco friendly fishing sinkers.
Hope i am not making a problem precipitating from the acidified ammonia soultion, but will keep all precipts wet and redisolve in HCL/ peroxide to start over again.

I have already redisolver the brick red precipts and will re-run them with Ammonia CL abd sodium Chlorate also. I wonder if the Ammonia Chlorice in the Ammonia solution did not drag down a lot of my Pd based on the solution color when redisolved.
Will let you know and thank you again for your help.
P.S. I will have piturecs of everything soon to show you as well.
Sincerely
Ron

rhwhite67 said:

PGM and Lou
Thank you for your response.

I simmered as mentioned and then let the solution set for several hours. The floculant/precipt started out as a white/yellowish color and slowly turned a brick red color and when I filtered the solution to remove it the solution was the light yellow color that Steve talked about. Testded the solution with DMG and positive for Pd. However when I added the HCL to precipitate it does not want to precipitate so I am following Lou's suggestion of the zinc except that i have no zinc available at the moment so am substituting Tin which is lower in the electromotive series and readily available at Walmart in their new eco friendly fishing sinkers.
Hope i am not making a problem precipitating from the acidified ammonia soultion, but will keep all precipts wet and redisolve in HCL/ peroxide to start over again.

I have already redisolver the brick red precipts and will re-run them with Ammonia CL abd sodium Chlorate also. I wonder if the Ammonia Chlorice in the Ammonia solution did not drag down a lot of my Pd based on the solution color when redisolved.
Will let you know and thank you again for your help.
P.S. I will have piturecs of everything soon to show you as well.
Sincerely
Ron

Click to expand...

if i am right tin wont do the trick....i used it on a test and it didn't work.......you need zinc 99.9% or copper just add it a small copper wire and it should all cement....i have done this with zinc but not copper and it works fine..copper is in most electrical wire just strip the wire open and pull out the copper......if you where in the UK....i would have posted you some zinc i have a large batch....i am sure you could buy some from steve check out his shop....

PGM
you wrote:

if i am right tin wont do the trick....i used it on a test and it didn't work.......you need zinc 99.9% or copper just add it a small copper wire and it should all cement....i have done this with zinc but not copper and it works fine..copper is in most electrical wire just strip the wire open and pull out the copper......if you where in the UK....i would have posted you some zinc i have a large batch....i am sure you could buy some from steve check out his shop....

Thank You for your kind offer to post some to me if I were in UK and yes I like the idea of Steves zink turnings that he has. I have Zinc at my lab but not here where I am. I am at home with my family for a few weeks off during/after the holidays and am trying to complete a few tests on this material on a hot plate in the back yard.

Based on the electromotive series and where tin falls in it, tin should work as well as copper and after-all tin chloride is basically what stannous chloride is made of.

Here's a very incomplete list of metals as they appear in the electromotive series.

Magnesium Mg
Aluminum Al
Zinc Zn
Chromium Cr
Iron Fe
Cadmium Cd
Nickel Ni
Tin Sn
Lead Pb
Hydrogen H
Copper Cu
Silver Ag
Palladium Pd
Mercury Hg
Platinum Pt
Gold Au

P.S. if you want tin to work best try dissolving it in HCL first making a cheap form of stannous chl then add it to your solution otherwise you need to add HCL to increase the acidity of your solution and make sure that the solution is denoxed so that the tin will disolve and go into solution easier.

Solid copper on the otherhand, while working well takes a long time if only used with a CL solution, like 2 – 4 days to cement all of the values from personal experience. Best options I have found with copper is to use a copper sheet or bar and then as the values cement to the copper scrape or wire brush them off. Because the PM's tend to cement to the surface of the copper, solid copper wire sucks for this as it is very hard to scrape or wire brush the PM's off of the small round surface of the wire and your only option becomes to throw it into a nitric bath to disolve the rest of the copper and then remove the Pd values from the nitric after you have filtered the rest from the solution. This or ultra fine copper powder 300 mesh or less or copper that I have disolved in nitric and precipitated with aluminum disolves readily into solution and the PM's precipitate out as black/brown sludge on the bottom of the beaker for further processing. Interesting thought though, copper shavings/turnings like Steve's zinc turnings would probably work well if they were fine enough as well and then just use nitric to disolve as with the copper wire. Just a thought, but I have tried all of the above with copper except the trunings with success. It just takes time.

P.P.S I tried the tin sinkers and hammered them flat and thin with a hammer on a piece of steel. As mentioned I added muratic to the solution to increase the acidity and they are working well for cementing producing a nice black sponge materiall as the sinkers disolve but even at this I have had to scrape the cemented PM's off of the surface of the tin twice so far.

WOH brain storm. I just remembered a highschool chemistry experiment that reminded me of this. US pennys after 1980 or so were made out of a zink slug coated with copper. If one really is in need of zink and does not have a supply handy to finish a test simply file a groove in some post 1980 pennys and toss them in the solution. The zinc will precipitate/cement the metals and any copper that goes into solution will only drop out the PM's anyway.
Gosh that was a long time ago.

Sorry for the rambling. Steve and some of the others thoughts of using Copper plate are dead on.

Ron

Wise people avoid the use of tin for everything except testing. It can be very troublesome in refining processes if filtration is required.

Harold

Thank you Harold.

I am using a regular coffee filter and it seems to be working fine. But this is the first time I have used Tin for this purpose.

Is that why everything seems to be sticky? I was thinking it was probably the small drop of watered down dawn dish soap I added to break the surface tension as it simmered down while the tin disolved as the sponge seems to want to float on top of the solution.

Or

Is it because the tin may have a tendancy to make too fine of a sponge/powder which would then be hard to filter?

So far the sponge I have gotten has been fairly large and in the form of small lfacks but this may be because of the way I flattened the sinkers paper thin.

In either case my cementation media of choice is usually always either Zinc or Copper, but in this case I didn't have any zinc and time is an issue for me on this one. As several have mentioned here on the forum, a chunk of steel in the stock pot for cementing all of your left over leach solutions and concentrating any missed values works very well before properly disposing of them and their precipts after you have checked them again for any missed values.

One other thought on cementation is that if you are using Steel or copper heating the solution will typically help the process go faster just as with any other dissolution process. Just be careful to only simmer it and do not boil it as you may boil/steam away some of your values.

Zinc and aluminum typically work very well at ambient temperature as they are much more reactive working faster than either steel or copper and all 4 of them are typically cheeper than tin which is another good reason to go with them.

Ron

It is also wise to try to avoid introducing copper to PGMs if you wish to sell pure metals as it is problematic to remove compared to zinc contamination.

Nice pics guys!. 8)