# Ammonia Soluble Hexachloropalladates (IV)



## kadriver

I have had this beaker sitting on one of my shelves for months containing Palladium dissolved in nitric acid.

The palladium came from mixed black PGMs, I extracted the Pd using dilute nitric acid, then evaporated it to remove most of the liquid.

I did a stannous test and it is loaded with palladium, the standard test solution on the left contains 100mg Pd dissolved in 100ml liquid

The spot on the right is a sample from the beaker that I am going to try and process to get ammonia soluble brick red [(NH4)2PdCl6] Ammonium hexachloropalladate (IV).


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## kadriver

I began by filtering the liquid to remove any mixed black PGMs (and any other solids) that may have made it into my Pd nitric acid extraction.


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## kadriver

This is what filtered out of the Pd/nitric solution - I'll wash this back into the mixed black PGMs as it may have traces of Pt and Rh and add the filter to my PGM paper storage.


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## kadriver

I transferred the filtrate to a 1 liter beaker and added zinc turnings to cement out the Pd.


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## kadriver

Here is a shot of the Pd that cemented onto the zinc turnings (beaker held up to the light and the photo shot from below). This was only about five minutes after adding the zinc - the Pd cemented out very quickly.


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## kadriver

This is as far as I got with this new project.

I covered the beaker and left my fume hood running until tomorrow morning.

Tomorrow I'll clean the cemented Pd black powder with dilute HCl to remove any zinc that remains, wash to remove all traces of nitric, and then dry and weight the Pd.

My goal is to end up with some pure palladium sponge for use with other PGM refining experiments.

kadriver


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## solar_plasma

Thank you for sharing!


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## RaoOvious

Kevin,

Make sure that there is no trace of nitric acid(water washes and Ph neutral) before washing the Pd black with dilute HCl,otherwise some of the Pd black would again go into the solution.


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## 9kuuby9

RaoOvious said:


> Kevin,
> 
> Make sure that there is no trace of nitric acid(water washes and Ph neutral) before washing the Pd black with dilute HCl,otherwise some of the Pd black would again go into the solution.



I Always keep a small Al rod in my Pd nitrate solution; If any slips back into the solution it would directly cement back; And Nitric acid does not attack Al so it has prefrence over Zn in a nitrate solution.

What would the optimal Ph be for cementation? and what base do you advice to use for increasing the Ph of a Pd solution without forming any complex Pd salts?


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## kadriver

RaoOvious said:


> Kevin,
> 
> Make sure that there is no trace of nitric acid(water washes and Ph neutral) before washing the Pd black with dilute HCl,otherwise some of the Pd black would again go into the solution.



Rao - I plan to rinse this over and over until the pH is neutral to avoid forming AR.

When I got to the shop this morning the supernatant was crystal clear and colorless with some left over pieces of zinc


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## kadriver

I used a pipette to remove all the clear liquid from the beaker after testing the liquid with stannous chloride.


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## kadriver

After the liquid is drawn off, I use a pair of plastic tweezers to remove the larger pieces of zinc left over that did not get dissolved.

I put the pieces of zinc in the small beaker containing the liquid that was drawn off from the large beaker.

If they are taken out and left in the air they get an oxidized coating, putting them in the liquid will help preserve them for use on another batch.

Having these pieces of zinc sit overnight in the solution with the Pd black powder will also help ensure that the nitric acid is used up.


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## kadriver

I then added some more distilled water to do another rinse.

Then I checked the drawn off liquid for PMs with stannous chloride - the test was negative which means all the metal has been cemented out of the solution.


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## kadriver

I waited all day for this second rinse to settle completely and it never did.

The liquid is a slight grey color after settling for about 8 hours.

I removed the liquid with a large 125ml pipette with a rubber bulb on the top to draw a vacuum.

Then I switched to a small disposable 3ml pipette to get that last few ml of liquid from the container.


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## kadriver

I added more distilled water for the another rinse and set the beaker aside with a cover to keep trash out.

Then check the pH of the previous rinse water - got a pH of 5 so the acid is fairly week which means the zinc destroyed most of the nitric acid.

This is as far as I got today - thanks for looking and as always critical comments are welcome.

kadriver


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## kadriver

Is there a flocculant that I can use to get this to settle quickly and not interfere with the reactions?

If yes, then where can I get some?

Thanks!

kadriver


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## samuel-a

Heat to a boil and let it cool back down.
Things tend to settle faster when the solution is hot.


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## kadriver

Thanks Samuel, I always boil the rinse water when processing gold and silver, I should have known this.

kadriver


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## lazersteve

Kevin,

Top notch post, great job as usual for you.

You can quickly clear the gray solution by packing a glass (or plastic) conical funnel neck with a small rolled up section of Charmin tissue and vacuuming the liquid thru the moistened Charmin plug. The plug will contain the suspended gray material and can be incinerated to recover the suspended material later. Don't pack the funnel neck too tightly or the filtration will take a long time. One to two drops per second is a good drip rate that will afford a clear solution under vacuum. Test the packed funnel under vacuum with water before adding the gray liquid. Try for the fastest drip rate that will produce a clear solution. Once you have the drip rate correct, add the gray liquid.

The filtered solution should be 100% clear and free of suspended particulate.

Steve


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## RaoOvious

9Kubby9 wrote

"What would the optimal Ph be for cementation? and what base do you advice to use for increasing the Ph of a Pd solution without forming any complex Pd salts?"

Ph of around 2-3.Use filtered concentrated solution of Sodium Carbonate or Bicarb.

Kevin, as Sam said,heating would make flocculation faster and easier but in case of even traces of nitric acid some black might get dissolved in the process so making it neutral first and then moving ahead seems efficient.


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## 9kuuby9

Thank you RaoOvious


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## freechemist

Hi kadriver,

Thanks for sharing your experiments, especially the pictures, staying in sharp contrast to a lot of photographic "artwork" shown up in this forum. Up to now, I have three comments regarding your posts:

1.) The title of the thread is simply wrong, because a salt like "ammonium hexachloropalladate(II)" doesn't exist. What you mean is ammonium hexachloropalladate(IV). The roman ciphers in the name stand for the oxidation-state of palladium in the respective compound, and this is IV (+4) in the only sparingly soluble (NH4)2PdCl6, ammonium-hexachloropalladate(IV), containing Pd(IV). There exists a chloro-complex-salt of Pd(II) too, ammonium-tetrachloropalladate(II), (NH4)2PdCl4, which is much more soluble in water, and as a solid, forms dark brown, needle-shaped crystals.

2.) In your last post from August 1st you ask for a flocculant: "Is there a flocculant that I can use to get this to settle quickly and not interfere with the reactions?" - To me it is not clear, what you mean by "this": the title-compound to be precipitated or the freshly washed, acid-free Pd-black? - Anyway, (NH4)2PdCl6 usually forms well formed, easily filtrable crystals, and a flocculant is not needed.
Pd-black, especially, if washed free of acid and/or dissolved salts tends to peptisize in water, that means, it seems to form sort of a colloid, settling only difficultly. According to my experience, in this case, it is sufficient, to add one tenth of the suspensions volume 32% HCl (muriatic acid), and give it, constantly stirring (e.g. with a magnetic stirring bar), a short boil during a few minutes. Usually the finely suspended Pd-black coagulates and becomes filtrable much better.

3.) For safety-reasons I, personnally, would not precipitate (NH4)2PdCl6, but the corresponding potassium-salt instead, K2PdCl6. Doing this, you never will have issues with NCl3 and/or potentially explosive chloramines.


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## kadriver

Freechemist;

Thanks for the insight. I got the information for the title by looking back through some older posts and transposing the information from these old posts. I am still a newbie beginner and do not have these terms memorized yet.

My goal is to form the Pd salt that is readily soluble in ammonia. Would that be the (NH4)2PdCl6, ammonium-hexachloropalladate (IV)?

I want to avoid forming the Pd salt that is sparingly soluble in ammonia. Would that be the ammonium-tetrachloropalladate(II), (NH4)2PdCl4? I can see where I made a mistake with the roman numerals. It appears that the title should have the (IV) instead of the (II).

Maybe one of the moderators would kindly change the title, if it can be done. What should the title be?

I have saved all the rinse water and some fluffy dark grey material has begun to form in the bottom of the beaker.

With respect to "this" in line item two of your post, I was referring to the suspended material in the rinse water. I was wondering if there is something that can be added to the rinse water to get the suspended material to settle quicker. 

Steve has offered a solution in the form of a tissue plug in a funnel. I have never used a "charmin plug" so here is another opportunity to try something new.

I also want to try your suggestion as an experiment to broaden my knowledge, so I'll divide the wash water and do both operations. I have a hotplate stirrer so it should be no problem.

I seem to remember a fault with using the potassium - it damages the fused quartz dish during incineration - if my memory serves me correctly. But I will do some more research and take the warning seriously - thank you.

kadriver


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## lazersteve

Kevin,

I have plenty of natural Sylvite (KCl) on hand and can send you a few pounds for free if you need them. Let me know via email and I'll get the KCl right out to you.

Steve


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## kadriver

I have done several more washes using distilled water and the pH has finally gotten to pH7 neutral.

The last pH test was a seven, but I did one more wash for good measure. I think I have done a total 7 washes - with the final wash being number 8.

I let each wash settle for at least 6 hours before decanting, testing pH and adding more distilled water for the next wash.

Notice the dark grey fluffy material that has coalesced in the bottom of the full beaker.

kadriver


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## kadriver

This is a shot of the 8th rinse after settling overnight.

The pH test was back to an acidic state of about pH6.

Don't know how that happened.


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## kadriver

The next step is to dissolve the residual zinc out of the black palladium with dilute HCl.

I scooped out a small portion of the Pd black powder from the main container and rinsed it into a small beaker with distilled water.

I added about 10ml distilled water to the small sample of Pd black, then added about 1ml of concentrated HCl.

The reaction began immediately with bubbling as the HCl attacked the bits of zinc.

I let the reaction continue until there was no more bubbles, then I added about 1/2ml more HCl and let it sit for another 1/2 hour.

Then I did a stannous test to make sure none of the Pd had dissolved.


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## kadriver

Before committing the entire batch to a dilute HCl treatment, I chose to see what would happen with a small test sample - because this is my first time doing this and did not know what to expect after adding dilute HCl to dissolve residual zinc.

My curiosity satisfied, I poured the test sample back into the main batch, rinsing all the Pd black out of the test beaker and into the main batch.

Then I added about 100ml or so of distilled water and about 10ml of HCl to the main batch, stirred, and got the same result as with the test sample.

There was fizzing and bubbling as the dilute HCl dissolved the last little bits of zinc that were too small for me to remove with tweezers.

I let the dilute acid sit over the Pd black powder for about an hour, adding a few drops of HCl to see if a reaction fizzed up - there was no more reation so I concluded that all the zinc was dissolved.


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## kadriver

I rinsed the black powder several times with distilled water.

The powder was very clean looking and settled quickly after each rinse.

The wash water was clean after each rinse - I did four rinses to ensure all the dissolved zinc was removed before going to the next step.

It there a reagent that can be added to the rinse water to precipitate the zinc? this would be a great test to ensure that all the zinc has been removed.


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## kadriver

This dilute HCl treatment really cleaned the Pd black powder up nicely.

It was fluffy and stuck together and settled very quick after washing.


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## kadriver

I got a clean dry 250ml beaker and weighed it to get a tare weight - I wrote the weight on the side of the beaker with a marker.

Then I transferred the Pd black to the 250ml beaker, rinsing all of it from the large 1 liter beaker.


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## kadriver

I poured off the rinse water, then gave it a few more rinses to make sure that the powder was nice and clean.

It settled and clung together so well that I could pour these rinses off very easily.


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## kadriver

Next I drained off all the water that I could and dried the powder in the beaker over low heat in my fume hood.

I then weighed the beaker with the dried Pd black powder to get the total weight of my product.

The tare weight of the beaker was 118.4g and the weight of the beaker and the dried black powder was 120.7g

The total weight of the Pd black powder was therefore 2.3 grams (120.7g - 118.4g = 2.3g).


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## kadriver

I then calculated the chemicals needed for the next step using the number 2.3g of Pd black powder.

I was instructed to use 5ml of a 90/10 solution of HCl/H2O2 for each gram of Pd black that is to be dissolved.

I wrote down the calculations and snapped a photo (hope my math is right here).

I am using AP (acid/peroxide) to dissolve the Pd black powder to avoid any nitrous compounds to be formed in with the Pd solution.

By avoiding the nitrous compounds I won't have to evaporate and rehydrate with HCl to expel the any excess nitric - because there won't be any nitric to expel.


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## kadriver

I set the beaker with the dried Pd black on the heater with the heat OFF.

Then I added the calculated amount of HCl required to dissolve the Pd black powder.

As soon as I added the concentrated HCl it turned orange - I have no explanation for this unless the conc. HCl has dissolved some of the finely divided Pd black powder by itself. I have heard that in this finely divided state that concentrated HCl can dissolve Pd - I hope that is what is going on here.

I added the 10.4ml HCl using a small pipette getting it as close to the amount needed as I could.

I decided to keep going with the experiment after encountering this unexpected color change.


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## kadriver

I put a cover on the beaker and then added the required amount of 40% hydrogen peroxide (got it at Sally's Beauty Store Supply for $4) to completely dissolve the Pd black.

I left this at room temp with no heat and let it stand overnight - more to follow.

kadriver


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## mjgraham

I have no input on the process but I wanted to say thanks for the photos and steps and info. The photos are great and of high quality, keep up the good work!


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## lazersteve

Kevin,

You are doing great. 

A few tips:

1. Place a stir bar in the final reaction beaker with the blacks and stir constantly during the dissolution.
2. Heat the reaction to 40C
3. Use the least amount of solution possible for the dissolution, with the lowest possible water content. PGMs precipitate best from concentrated solutions.
4. You could have used the chlorine generator and HCl, instead of 10:1 AP, to dissolve the mixed blacks, increasing the concentration of the resulting solution while reducing the liquid waste generated.

A side note to the process you have chosen:

You also could have used diluted warm nitric acid to dissolve only the Pd from the mixed blacks and precipitated the refined Pd directly from the nitrate solution using any one of several reagents (DMG, SO2, NH4Cl, Formic Acid, Hydrazine, etc. ) without denoxxing. Nitric acid will not attack Pt black ( assuming no chlorine is present), but acid peroxide/chlorine gas will, even at room temperature. If your goal is to put both Pd and Pt back into solution together, then 10:1 AP will work fine. Just remember, your precipitated Pd/Pt salts from the pregnant AP solution will contain drag down cross contamination of the sister metal (Pt/Pd) salt, thus requiring you to refine them both again for highest purity.

Keep up the excellent posts.

Steve


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## kadriver

Great tips Steve - thanks.

I did not use chlorine gas because in the next step it (chlorine gas) is used to precip the ammonia soluble hexachoropalladate.

But what I did not think of is the fact that ammonium chloride will be added after the dissolution (where I could have used Cl gas instead of AP) and before the precip of the hexachloropalladate.

Its still all new to me and I am learning by doing as I go, making mistakes but learning from them. Plus others can follow this thread and learn from my mistakes.

kadriver


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## kadriver

When I got to my shop the next morning I was surprised to find that most of the black powder remained un-dissolved.

I expected it to be completely dissolved after sitting in the AP overnight (but as Steve pointed out, there should have been stirring and heat added).


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## kadriver

I ended up making several more additions of hydrochloric acid and hydrogen peroxide with some med-low heat.

It really fizzed up when I added the H2O2, but I could tell that more of the Pd black powder was dissolving because the solution began to get so dark that I could not see through it even when held up to the light.


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## kadriver

It got to the point where I could not tell if there was any black powder in the bottom of the beaker, so I poured off the solution into another clean beaker.

Sure enough there were some particles of Pd black powder that were still un-dissolved. I worked on this all day to this point adding fresh HCl and H2O2.


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## kadriver

I rinsed down the sides of the beaker containing the un-dissolved Pd black powder with fresh hydrochloric acid.

Then I put the cover on and added a little fresh H2O2 - the remaining Pd black powder dissolved right in front of my eyes in just a minute or two.

then I added this back to the main solution.


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## kadriver

I evaporated off much of the liquid before I went to the next step

Then I made up some fresh saturated ammonium chloride solution and added drop by drop to the dissolved Pd black solution and got another surprise.

I was expecting just a little Pt orange powder (if any) to precipitate out. But there was much more platinum in those "Pd blacks" that I expected.


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## kadriver

I filtered out the orange Pt powder and will save it until I get a good quantity then burn it in a quartz dish.

The filtrate should be my palladium - more to follow.

kadriver


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## lazersteve

Have you performed a stannous test for Pt on a sample of the newly formed orange salt?

Steve


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## kadriver

No, I'll get some of the orange powder out of the filter and dissolve a little in water and check - but what else could it be?

kadriver


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## RaoOvious

Kevin, 

By the look of your salt you have most probably made Palladium Tetrachloropalladate (II) with some Pt salt (NH4)2PtCl6.(If Pt is in sol.).The reason for this is your solution is extra-concentrated.It is very normal in successive precipitation of Pt & Pd.

To solve this you would have to rinse the filtered salt with water back to the filtrate,add some ml's of HCl,heat and concentrate it to 20ml/gram or at a con. level where it doesn,t form this thick and fluffy salt upon cooling(Normally it would range from 20-10ml/gram).

If there is any platinum then it would precipitate as fine orange/yellow powder not like this fluffy and thick Palladium II salt.And then you can proceed for Pd as per usual route.


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## freechemist

*Kadriver writes:*
_I have had this beaker sitting on one of my shelves for months containing Palladium dissolved in nitric acid. The palladium came from mixed black PGMs, I extracted the Pd using dilute nitric acid, then evaporated it to remove most of the liquid. I did a stannous test and it is loaded with palladium, the standard test solution on the left contains 100mg Pd dissolved in 100ml liquid._

The brown stain on the left corresponds to the reference-solution, containing 1g Pd/liter. The stain on the right shows clearly, that Pd and Pt are present. The Pd-concentration in the sample-solution seems to be much higher, than 1 g Pd/liter. The Pt-concentration, as indicated by the strong orange coloration of the paper, concentric around the dark-green Pd-stain, seems to be quite high, too. One can distinguish between Pd and Pt by washing the stains on/in the paper with copious amounts of distilled water. The Pd-stain (dark green) will disappear slowly, being washed out completely, whereas the orange Pt-stain will stay back on/in the paper.

*RaoOvious writes:*
_Make sure that there is no trace of nitric acid(water washes and Ph neutral) before washing the Pd black with dilute HCl,otherwise some of the Pd black would again go into the solution._

In my practice, this was never a problem. In contrary, a too low electrolyte/acid-concentration can lead to peptization of such PGM-blacks, making their filtration more and more cumbersome. Assuming a rest-wash-solution-pH of 2 for the last filtration step, and a volume of 5 ml liquid means, that a maximum-amount of 5*10-5 moles HNO3 is available, to oxidize a maximal amount of 5*10-5 gram-atoms Pd-metal to Pd(II), corresponding to a maximal possible loss of 5.3 mg Pd, in an experiment like presented here, by Kadriver.

*@Greyish solution after cementation and intensive washing of Pd:*

This greyish colour/turbidity may well be caused by small amounts of residual, unreacted zinc-powder, reacting slowly with water to very small particles of insoluble zinc-hydroxide, Zn(OH)2. Thus it is not necessary, to filter. Chance is, that this turbidity disappears on addition of some diluted acid.

*@Kadriver:*

As I can see from your last posts, you're on a very good way. First, dissolving residual zinc with diluted HCl, followed by filtering, washing, drying. This leaves you with a weighable amount of raw Pd-powder, and you know now much better, what you are working with.
You already have dissolved the Pd-black in HCl/H2O2, which should leave you with a solution containing mainly Pd(II), together with some Pd(IV).
Contrary to you, I am not surprised, to see how much Pt you are precipitating. SnCl2-testing to me shows clearly the presence of quite a lot dissolved platinum.
In order to clarify my comments I have collected some of your fotos in the attached pdf-file.


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## kadriver

Thanks for each of your responses - by posting the pictures one can see the progress and the mistakes I make as I go. This is the reason I post many photos of my experiments with the platinum metals - and I greatly appreciate the inputs given by each member who responds. The forum can watch as I grow (or fail) as a novice PGM refiner.

I picked out a small piece of the salt from the filter and put it in a spot plate.

Added a few drops of water to see if it would dissolve - it did, so I drew the test sample up in the pipette and expelled it back into the cavity to get it dissolved completely and to mix thoroughly.


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## kadriver

I dipped a piece of filter paper into the mixture and then added a drop of stannous chloride - it turned brown which would indicate Pd.

Then I placed a drop of Pd standard solution (100mg per 100ml liquid = 1 gram per liter concentration) in the cavity to the left of the test sample.

Placed a drop of Pt standard solution (100mg per 100ml liquid - 1 gram per liter concentration) in the cavity to the right.

Then added a drop of stannous chloride to each sample in the spot plate.

After doing these tests I believe that the salt in the filter is NOT platinum, but mostly palladium with very little, if any, platinum.

I plan to re-dissolve the Pd salt from the filter back into the rest of the filtrate with distilled water, then concentrate it through evaporation again.

The last evaporation was down to about 20ml or so.

This time I'll only take it down to 40ml, then add the concentrated ammonium chloride to get any Pt (if present) to precipitate out.

I'll be following the procedure given by RaoOvious above.

I'm glad I was instructed to test it otherwise I would have just assumed it was Pt salt (which is was NOT as per the sample test results).

Thank you!

kadriver


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## lazersteve

I suspected you may see that you had precipitated Pd and not Pt, this is why I suggested you do the stannous test on the orange salt.

When I precipitate Pt from mixed PGM solutions it is typically a bright orange color if contaminated with Pd:







Iridium contamination will give a brick red colored Pt salt:






Rh contamination gives a yellow green color (top left filter):






and lastly, nearly pure Pt with will be canary yellow:






As a general rule, the lighter yellow and denser the Pt salt (see note in post below), the higher the purity.

Notice that all of these salts pictured above are dense and do not have any transparency to the crystals. The transparency is typical of precipitations done with highly saturated ammonium chloride solutions which naturally tend to entrain other PGMs in the crystals.

Your test results is a prime example of why you must always test regardless of what you believe you have produced. 

Keep up the great work Kevin, your posts are a prime example of what makes the forum great.

Steve


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## lazersteve

Lou pointed out to me via PM that Pt ( and PGM salts in general ) are more fluffy as the purity increases, therefore they are technically less dense.

I incorrectly used the term density above, when in fact I was referring to the difference in appearance between relatively pure PGM salts and those that have a large excess of crystallized ammonium chloride in them. These entrained salts have a slightly transparent crystal color and look slushy as opposed to packing 'densely' and clumping into the filter with a consistent color throughout as seen in my photos.

Here's an old thread with a prime example of what I was referring to:

Entrained PGM salt photos thread

and a sample photo from the thread:

Entrained PGM salts

Note how the salt appears glass like and not 'densely packed' as the photos I posted above.

Thank you for correcting my terminology Lou, it's good to know someone is keeping me straight! :wink: 

Steve


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## RaoOvious

kadriver said:


> This time I'll only take it down to 40ml, then add the concentrated ammonium chloride to get any Pt (if present) to precipitate out.
> 
> I'll be following the procedure given by RaoOvious above.



Kevin thus you have precipitated (NH4)2PdCl4 with minimal amount of Pt salt as already enumerated above.After concentrating this Pd salt with the filtrate, in fact you do not need to put in more NH4Cl as it is already present in the mix.

What you have to critically evaluate is concentrating it to around 20ml/gram,let it cool and see if there is orange/yellow fine grain Pt salt appearing without the thick and dense Pd II salt,if yes you are good to go for filtration of Pt salt,if orange yellow Pt salt is appearing with the usual suspect thick Pd II,then you would have to dilute it a bit with 50/50 Distt.water/HCl and give it heat until thick Pd II salt disappears,and then go for filtration.

If at any concentration level there is no indication of orange/yellow fine grained Pt salt then you can safely concur that there is no Platinum or its in mil or micro grams,then you can straight away go ahead for chlorine addition without filtration for Palladium Precipitation. 

But as per your elegant pictorial presentation,I guess you would have some orange/yellow fine grained Pt salt at some level,around 15-20 ml/gram concentration level.The rule of thumb is the more concentrated your Pt,Pd solution after addition of conc. NH4Cl is,the more chances there are of appearing and mixing of thick brown needle shaped Pd II salt with your desired orange/yellow Pt IV salt. 

For clarification purposes have a look at the pic where the grains are free and fine and are not interlocked(except here the salt is of Pd not Pt,just for grain finess purpose) like Pd II or you can call form ur beautiful yellow Diammine Pd II salt which you did last year.

I hope this would help,anyways keep up the great series.

Rao


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## kadriver

I over - concentrated my solution by evaporating it too much and formed the ammonia insoluble (NH4)2PdCl4 upon adding the concentrated ammonium chloride.

Since I have 2.3 grams of Pd black powder as weighed in earlier in this post, then I should only concentrate my solution volume down to 20 x 2.3 = 46ml.

I was thinking, "the more concentrated the better". But this is not the case. The 15ml to 20ml per gram of Pd black powder concentration factor is a critical number.

I'll give this a go as soon as I get some time freed up. More to follow.

kadriver


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## RaoOvious

Kevin,

This pictorial presentation might help you in the current scenario.It show separation of Pt (IV) salt in a combined solution of Platinum and Palladium.Specially the color of Yellow Pt. (IV) salt,this is how should be yours' at that stage.

Further I would be uploading further pics of the situations where thick brown needle shaped Pd (II) is also precipitated when precipitating Pt. (IV) or when concentrating the Pd rich solution(for Pd IV salt precipitation by introducing Chlorine gas) after clean separation of Pt.(IV) salt from the combined solution.


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## RaoOvious

Continued..................


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## kadriver

Great photo presentation RaoOvious - thank you.

I got behind on some things but I am starting to get caught up.

I still have the Pd salt in the filter, will re-dissolve and then re-concentrate and watch for the fine Pt salt to form.

These photos will help as a reference.

kadriver


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## kadriver

I got some time so I continued the process here.

I removed the filter paper, now dry, with the Pt/Pd salts and rinsed all that I could into a 1 liter beaker.

There were crystals of ammonium chloride on the filter paper from the previous precipitation that rinsed into the beaker with the Pt/Pd salts.


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## kadriver

This is a photo looking straight down into the 1 liter beaker.

Some of the salts did not dissolve - you can see a pile of the salts collected in the center of the bottom of the beaker.

I did not add any HCl, just distilled water.

After reviewing the instruction I see that I was supposed to add "50/50 distilled water/HCl"

I'll add some HCl when I get back to the shop and see if the salts will dissolve.


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## kadriver

In a short amount of time some yellow powder began to appear floating on top of the liquid in the beaker.

As time progressed the yellow salt began to accumulate on the bottom of the beaker.

Since I have no experience with this, I can only assume that this yellow salt is the platinum.

It is quite yellow in appearance.


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## kadriver

My next task is to get the rest of the un-dissolved salt to dissolve by adding in a little HCl.

Then I'll filter out the yellow powder and add the filtrate to the main solution and re-concentrate to about 46ml.

Then filter out any more Pt salt that forms.

Then, if all goes well, chlorinate the solution with chlorine gas to form the ammonia soluble hexachloropalladate (IV).

kadriver


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## Lou

Looks more like mostly a Pt gig.


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## kadriver

The liquor does look orange. I'll know more later today.


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## kadriver

I had forgotten all about this post.

I still have the beaker sitting somewhere in my shop - probably dried to a crisp by now.

I need to get this back out and start working on it again.


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## kadriver

I jumped out of bed and went to my shop.

Sure enough, there was the beaker up on a shelf long forgotten.

It is dry as a bone, how should this be re-hydrated?

It already has 15% ammonium chloride in with it, just add a little distilled H2O?

I have some more15% ammonium chloride solution.


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## Lou

Mix of complex Pd/Pt salts and chloroplatinates, by visual appearance and correlating with what I said before up thread before you forgot about it.

You can digest it all in aqua regia and rid it off ammonium chloride, and start over.

Lou


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## kadriver

That's what I'll do Lou, thank you.


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## kadriver

I got this dissolved again and I will start it all over again.

I also have some more PGM from DMG precipitations out of silver digestions.

I am going to throw it all together (unless someone here tells me not to).

I also have a platinum ring that I may dissolve and throw in the mix - unless this would be unwise (the ring XRF'd at 93.5% Pt)


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## Lou

You better roll that ring out or you'll be dissolving it til the cows come home.

Usually we melt with copper for bulk metallics, sample, off to the races.


You need to make a game plan and follow the flow sheet.


Lou


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## kadriver

Lou,

I've got a friend who has a metal roller and I'll get him to help me roll it real thin.

I remember trying to dissolve a piece of Pt the size of a match head - it took about 6 hours and still wasn't completely dissolved.

I am using old knowledge from doing this the last time, it seems much easier this time since I've done it before.

Starting over was a good suggestion.

I got the salts dissolved in hot AR

Edited once to correct photo


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## kadriver

I added zinc turnings after filtering.

The solution was concentrated and the zinc turnings turned almost instantly into black powder.

Edited once to correct up-side-down photo


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## kadriver

I had a bunch of filters with DMG precipitated Pd so I put them in a beaker and dissolved in hot AR - filters and all.

Edited once to correct. Up-side-down photo


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## kadriver

After everything dissolved I put some ice in to cool the solution so it would not blow a hole in the filter paper.

Edited once to correct up-side-down photo


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## kadriver

Stannous test to verify I had metal in solution.


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## kadriver

I filtered the solution to remove solids then put the solution back in the cleaned beaker


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## kadriver

I then combined the two batches into one beaker and added more zinc turnings to get the PGMs to cement out as black powder.


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## kadriver

The zinc was getting dissolved fast by all the excess acid so I added a little sodium carbonate to get the pH adjusted up. I should have done this first before adding the zinc to pH 2 to 3. Still learning.


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## kadriver

The PGM blacks were coming out of solution nicely.

This is as far as I got this evening.

I have about 5 pounds of pure zinc that I ordered. My friend has a big milling machine and he is going to let me use it to make turnings out of these bars in the morning at 9am so I got to sign off and get some sleep.

More to follow.

kadriver


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## mls26cwru

thank you for restarting this thread... I think i am going to be dealing with Pd soon, so i am going to be following this thread closely! thanks again!


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## Lou

Kevin,

The suggestion of dissolving all of the ammine complexes in AR was to save you the step of cementation and introduction of more impurities. A little zinc is probably helpful on the Pd refining side. 

When digested in aqua regia, ammonium hexachloroplatinate (palladate, other ammine compounds), the amine ligand or ammonium cation is oxidized away.

Basically, one can reflux in aqua regia any hexachlorometallate, or ammine chloride, and get the respective metal acid. You are oxidizing away the nitrogen. 

So, (NH4)2PtCl6 + excess NOCl + H(+) ---> H2PtCl6 + NOX/N2 gases; similarly for Pd.
You can digest Pd(NH3)2Cl2 in aqua regia and get [PdCl4](2-)

It is done when gas evolution stops and no more yellow salt remains to be seen. 

Anyhow, your next step is to either to separate the Pd by the chlorate method, or to run a hydrolysis.


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## kadriver

Lou, I was wondering what would happen to the ammonium chloride in AR.

How about the nitric from the AR, the zinc take care of that? Should the dissolved yellow Pd salts be de-noxxed by evaporation?

I did not denoxx but just went ahead and added zinc turnings to the filtered Pd/Pt solution.

I was gone all day and did not get to the shop until about 9pm.

This is what the blacks looked like when I got there;


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## kadriver

There were still some pieces of zinc in the black powder so I picked them out with tweezers rinsing the black powder off each piece of undissolved zinc with distilled water from a spray bottle.


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## kadriver

Then I began to rinse the blacks with distilled water to pH 7.

I did this to ensure there would be no nitric present because the next step is to remove any remaining bits of zinc with dilute HCl. I don't know if this step to remove the nitric with repeated distilled water rinses was necessary or not.

I began the rinses by adding distilled water to the blacks and checking to pH with a pH test strip - it was bright red pH 1 due to the acid present from the AR.

I poured the wash water that contained suspended PGM blacks into 4 plastic bottles about 125ml each.


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## kadriver

After carefully weighing each bottle I placed them into the buckets of the centrifuge.


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## kadriver

Then I spun then at 1100 rpm for about 10 minutes


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## kadriver

The suspended black powder (which usually takes for ever to settle) was all at the bottom of the bottle so I carefully decanted the clear liquid and added the liquid to my PMG stock pot (a 3 liter glass jar I got at the thrift store).


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## kadriver

Then I added more black powder to the bottles and spun it again, decanting the clear liquid each time.

I repeated this until all the black powder was in the bottles.

After adding distilled water to the black powder in the bottles and spinning for 10 minutes at 1100 rpm for fives times the pH was up to 4


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## kadriver

After each spin I decanted the clear wash water leaving only the black powder at the bottom of each bottle. I then squirted distilled water forcefully into the black powder to rinse it real good.

Then I would spin it again, 10 minutes at 1100 rpm.

I had to use these tweezers to get the bottles out of the buckets because they were flush with the top of the buckets and I could not grab them


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## kadriver

It took nine rinses as described above to get the pH to 7 and over a gallon of distilled water.

Like I said before, I do not know if this step (rinsing and spinning to rid the black powder of acid) was necessary or not.

It only took me 3 hours to rinse the powder free of acid.

For those who don't have a centrifuge however, this process would have taken much longer because this stuff does not settle very easily.

My next step is to treat the black powder in 50/50 dilute hydrochloric acid to remove any bits of zinc from the black powder.

More to follow.

kadriver


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## kadriver

RaoOvious said:


> Kevin,
> 
> Make sure that there is no trace of nitric acid(water washes and Ph neutral) before washing the Pd black with dilute HCl,otherwise some of the Pd black would again go into the solution.



I went back to the top of the thread and found this statement.

So the washes were necessary.

Tomorrow I'll do the dilute HCl treatment then I'll set up the chlorine generator and dissolve the black powder using chlorine gas to completely avoid any nitrates in the mix.

Cheers!

kadriver


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## kadriver

mls26cwru said:


> thank you for restarting this thread... I think i am going to be dealing with Pd soon, so i am going to be following this thread closely! thanks again!



I missed this, glad to hear that you are watching.

I've got to learn how to get the PGMs out because I am starting to see a lot more of them now.

One key ingredient to success in ANY endeavor; a strong desire to make it happen. Without this I only operate at half steam or just do enough to get by.

I want to save any Pt that comes out of this until I have enough to do a bromate hydrolysis. 

Hope this helps you - I can't wait to get the pure Pd sponge at the end!

kadriver


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## kadriver

I decanted the last wash water then added a little distilled water to each bottle.


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## kadriver

Then I added an equal amount of HCl to dissolve any remaining zinc particles left over from the cement action process.

There was no reaction, no bubbles at all. I thought there would be a little fizzing as the zinc dissolved.


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## kadriver

Just to make sure, I transferred the contents of each bottle to a beaker and added some more HCl and let it sit for about an hour.

I even used HCl to rinse the inside of the bottle instead of water - the HCl was greater than 50/50 concentration and still no reaction at all.

I concluded that all the zinc was gone.


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## kadriver

Just like last attempt at the beginning of this thread, the HCl cleaned the black powder nicely.

It was fluffy and settled almost instantly.


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## kadriver

I decanted the HCl with a small pipette and then did a couple of washes with distilled water.

Each time the powder clumped together and settled instantly.

I decanted the last rinse and then put it on low heat to evaporate the liquid from the black powder in a beaker with the tare weight of the empty clean dry beaker written in the side of it


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## kadriver

After about an hour the powder was bone dry, I did increase the heat to medium towards the end of the evaporation.

The powder looked clean and ready for dissolving in chlorine gas.


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## kadriver

I put the beaker on the scale to weigh the black powder, it was 8.2 grams of dry black mixed PGM powder.


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## kadriver

I then rehydrated the black powder with a little full strength HCl.


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## kadriver

I poured the mixture into a 250ml gas bubbler using straight HCl to rinse the black powder out of the beaker and into the bubbler.


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## kadriver

And now to assemble the chlorine gas generator.

The small bottle on the right contains a crushed up tablet (they are about 3 inches in diameter) from the large container on the left.

I put the large tablet inside of a large heavy plastic freezer bag by Glad.

Then I put that inside of another Heavy glad freezer bag and gently as possible so as not to put a hole thru the bag, set it on the concrete floor and carefully crushed it into a powder with light blows with a hammer.

It worked perfectly.


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## kadriver

Here is a close-up of the label for the chlorine tablets. I got them at Lowes in the swimming pool section.

The label says "trichloroisocyanuric acid".


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## kadriver

I fashioned a paper funnel out of a sheet of paper and some masking tape and poured the entire contents, one crushed up 3 inch tablet, into the gas generator reaction flask with side arm output.

Please notice that I am doing this in a fume hood. Don't try this inside an enclosed space or room as deadly chlorine gas is going to be generated and once the reaction starts it really can't be stopped.


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## kadriver

I added a little distilled water to make a slurry out of the trichloroisocyanuric acid.

This greatly increases the efficiency of gas production. 

Using the powder dry don't work so good because I tried it the first time I did this.

The gas flow was erratic and difficult to control.

With a slurry mixture the flow of gas can be regulated much better.


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## kadriver

Next I fitted the flask with a 250ml equalizing funnel and charged it with about 200ml of concentrated hydrochloric acid.


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## kadriver

Here is a shot of the entire assembly ready to start chlorine gas production.


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## kadriver

This is the chlorine gas generator apparatus completely set up and ready to run.

Again, please notice that this is inside a fume hood. This gas is very dangerous and this can't be done inside a house or other enclosed space.

Once I open the stop cock on the funnel, deadly chlorine gas will be produced and the reaction can't be stopped.

My emergency plan in case of a power failure is to turn off the flow of acid and then carefully tote both stands out the back door and place it in the middle of my back yard.

I have discovered that a regular 3M respirator will provide a little protection to enable me to transported the apparatus outdoors.

A respirator is not recommended because it will not filter the gas, but it is better than no protection at all.

I got a whiff of this gas once by getting too close to a leaching bin and it almost brought me to my knees.


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## kadriver

I started the drip at about one drop per second and the gas began to flow immediately.

I must say that this was one of the more pleasurably experiments that I have done in a long time.

I could increase the flow or decrease the flow of gas by adjusting the drop rate from the equalizing funnel.

That is concentrated HCl and the mixed PGM blacks inside the gas bubbler, about 100ml of HCl.

It started to get darker as soon as the gas started to bubble thru it, indicating that the powder was being dissolved by the gas flow


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## kadriver

At no tine did I smell even a hint of chlorine gas during this whole experiment.

Notice the color inside the generating flask, it looks menacing!


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## kadriver

After about 10 minutes the liquid began to turn red looking, the photo is not the same as if viewed in person.

It looked like red wine.


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## kadriver

After about 1/2 hour I could no longer see through the solution inside the bubbler.

I held a bright flashlight behind the bubble and then I could see through the solution.

Notice that most of the powder is gone in this shot.

Only a small amount of the black powder remains in the bottom. 

It can be seen in the front and to the left a little inside the bubbler while illuminated with the flashlight.


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## kadriver

Finally the solution became thick and looked blood red, no amount of light would pass through the solution.

It took about 1.5 hours to get to this point.

I did add another 200ml charge of HCl part way through this process because the first 200 ml had been used up.

At this point the TCA was expended and the gas slowed down no matter how much HCl I added.

I did swirl the reaction flask and got a little more gas.

I also was able to swirl the bubbler since it was clamped into a stand.

Swirling seemed to help dislodge black powder that was built up inside the bottom of the bubbler.

I could not see any black powder, but my experience tells me that there is probably a little undissolved left in the bottom of the bubbler.

This is as far as I got - this was much fun and I really enjoyed doing this.

Everything is going much smoother this time around.

Tomorrow I'll probably add some HCl to the bubbler and recharge the chlorine generator to get the last of the black powder to dissolve.

kadriver


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## Lou

Kevin,

Finish the digestion with some peroxide


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## kadriver

Lou,

Great idea. This would be much easier than setting up the chlorine generator again. I'll do it as soon as I get back to the shop.

I spent this whole day cutting down an 80 foot yellow pine tree that kept dropping branches and poking holes in my roof - I didn't even get to work a little today on this experiment.

Thanks again for the AP suggestion!

More to follow.

kadriver


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## kadriver

I had some more PGM solutions sitting around so I gathered then together and evaporated them to collect the black PGM powder.

This is 6 liters in these two beakers, it started out as about 15 liters - I evaporated off over 9 liters of liquid.

I think I over evaporated because this horrendous looking salt began to form, even while it was hot.

This photo is after the solutions had cooled to room temp.


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## kadriver

I decided to try and filter the salt out and keep evaporating, but the solution was vey syrupy and took a long tine to pass through the filter paper even under vacuum.


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## kadriver

Here is what it looked like in the beaker.


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## kadriver

I was asked to test a little of the salt so I got a little piece and dissolved it with dilute HCl right in the spot plate cavity.

It dissolved easily and the stannous test revealed what looks to be some platinum.


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## kadriver

I dissolved the remaining salt with dilute HCl and added back to the main solution, then added zinc shavings/turnings and cemented out all the PGMs.

After washing and drying there was 2.8 grams of additional black powder that I am planning to add to the original 8 plus grams.

I decided to dissolve with acid/peroxide instead of chlorine and began dissolving the 2.8 grams.

I used 40% H2O2 from Sally's Beauty Supply.

But after a while on the hot plate stirrer I began to see a white to pale yellow precipitate form.

I think I did not get all the zinc out before I started the AP.

Can this be filtered out after all the mixed black powder has been dissolved?

Or should I start over and cement back onto zinc?

kadriver


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## kadriver

Here is a photo of the precipitate mentioned earlier (top photo).

I've been so busy with other refining tasks that I have not had time to do anything with this.

But I am starting to see more PGMs coming through my shop.

The bottom photo; stannous tests taken from solutions that dissolved some jewelers filings and clippings.

Those orange test strips where taken AFTER the gold had been precipitated.

The test came from the green solution in the middle photo after the gold was precipitated with SMB.


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## kadriver

I'm getting ready to refine the Pd salt from my silver cell slimes that I just posted. Believe it or not, I've still got the solutions of palladium that I was working with in this thread!

I've completely forgotten how to do it because it was several years ago. But now I'm ready to shoot a video of the entire process.

i may have to do this in several parts.

kadriver


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## Lou

Would you like any advice?


There are some methods you can use that are not the traditional [PdCl4]2- to [Pd(NH3)4]2+ method that most use. That method largely but inadequately separates Pd from Pt.

In that method, one boils the freshly oxidized solution...Pd(IV)-->Pd(II) + Cl2 while Pt remains Pt(IV) and can come down as X2PtCl6 and is rinsed with ammonium or potassium chloride that is slightly acidic. The liquor is then made ammoniacal and the pink salt dissolved up. Pure Pd yields a colorless solution. Filtration from any hydroxides and then acidification with HCl to a pH of 2 yields Pd(NH3)2Cl2, the yellow salt often found as an end product of conventional Pd refining.

If you're interested Kevin, we can talk about about the bromide method. In my opinion, the bromide method makes as good as Pd as any other!


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## Lino1406

Wouldn't be the same result if dropping the TCCA (or KClO3) inside?


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## Lou

Can you elaborate Lino?


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## Lino1406

I watched the system that produces chlorine and drives it into the system. Instead, I know the KClO3 method, which by dropping KClO3 into the solution produces chlorine in situ and I assume TCCA will do same.


----------



## Lou

I see.

Much better to use TCCA (method on sciencemadness.org) as no risk of ClO2!


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## kadriver

Lou said:


> Would you like any advice?
> 
> 
> There are some methods you can use that are not the traditional [PdCl4]2- to [Pd(NH3)4]2+ method that most use. That method largely but inadequately separates Pd from Pt.
> 
> In that method, one boils the freshly oxidized solution...Pd(IV)-->Pd(II) + Cl2 while Pt remains Pt(IV) and can come down as X2PtCl6 and is rinsed with ammonium or potassium chloride that is slightly acidic. The liquor is then made ammoniacal and the pink salt dissolved up. Pure Pd yields a colorless solution. Filtration from any hydroxides and then acidification with HCl to a pH of 2 yields Pd(NH3)2Cl2, the yellow salt often found as an end product of conventional Pd refining.
> 
> If you're interested Kevin, we can talk about about the bromide method. In my opinion, the bromide method makes as good as Pd as any other!



Thanks Lou. I'm looking to go the easiest and least technical route. I did some before and got some metal. I dissolved the brick red Pd in ammonia, then acidified with HCl, filtered out the Pd salt and calcined It in a fuzzed quartz dish. It made 992 palladium. It worked well for me and seemed straight forward.

What's the pay out for palladium. If I sell it, can I just send you the sponge? Thank you.

kadriver


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## anachronism

To quote a very well respected Australian forum member:

"The only reason I am still here at my ripe old age is because I let other people play with PGMs. Most of them are dead now."


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## NanoCat

Lou,
so what is your non traditional method for the Pt/Pd separation? 
I have mixed PGMs that came down as primarily Canary Yellow with some deep orange. I have hit it with KClO3 getting it hot to 77C and the pH is 1.8.
The oxidizer is slowly going off and the yellow layer in the beaker diminishing.
The supernatant is mostly clear pale yellow. Again all the PGMs are in that mix but if I can get even the Pd and Pt isolated that will help me get those to the refiner.


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## kadriver

I finally got my palladium refined.

I've turned this post into a video

here is the link to the video:

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=52&t=26855

any comments would be welcomed

Thank you

kadriver


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## kadriver

Here is a picture of the pure palladium button 3.6 grams from the video


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## kadriver

kadriver said:


> Here is a picture of the pure palladium button 3.6 grams from the video




It sold for $150 through my eBay store.


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## VK3NHL

Great Video's as usual Kevin... Thanks for sharing..
regards
Tony


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