Refining of Palladium and making its salt

A. Hey there!

My father owns a precious metal refining company down here in Sydney Australia. I have been working there for 2 years now and only in the last 6 months have we started to refine platinum and palladium.

Best way is to dissolve the platinum and palladium in an Aqua Regia (4:1 Hydrochloric:Nitric) and set to simmer for about 2 hours. Platinum and Rhodium will not dissolve at room temperature. Once completed neutralize the nitric by adding a scoop of urea (add slowly!) and once frothing stops transfer into crystallization dishes and set to boil till liquid is down about halfway. Add ammonium chloride and stir and you will see a red/orange mud precipitate. That's your palladium/platinum. Of course it's not as easy as it sounds but those are the basic steps.

Hope I helped a bit.

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A. Put your dirty Palladium in a bath of nitric acid (1 quart sulfuric to 1/2 cup of sodium nitrate ⇦ this on Amazon [affil link] if you want to make your own weak Nitric acid =30%) Once thoroughly bathed pour off the acid into a new container leaving the rest to be discarded, add Sodium chlorate to the acid and the Palladium will drop out looking yellowish then turn a blue/green. You can also drop it with dimethylglyoxime (DMG) out both Nitric and Aqua Regia...but it hard to find and really expensive.

I don't know if this what you are looking but it's what I know to do.

Platinum specifically is very dangerous to refine/recover. One small drop of solution to your skin and you will get a disease called Platinosis. It has no known cure and is essentially a really horrible asthma like allergy. You can also get it through breathing in any gasses made from reactions (such as HCl + calcium hypochlorite) or just the fumes of refining (melting) the metal. I suggest to either stay away from it or definitely invest in the proper PPE (good respirator, lab coat, chemical gloves, fitted goggles, and either build or buy a fume hood).

A. When recovering Pt & Pd from spent Aqua Regia do not add urea as Platinum does not precipitate completely in the presence of nitrogen compounds, the classic method of boiling the acid to syrup to expel the nitric is the only way for a small scale operation to completely recover the platinum. As far as the Pd from dragouts the best method to quantitatively collect the Palladium is to digest the impure Pd in 50% nitric acid and selectively drop out the Pd with dimethylglyoximide.

A. I saw a post saying a small scale operation needs to boil the acid to expel all the nitric acid to recover all the platinum, however I refine precious metal, and have been told that the platinum will not drop out of aqua regia unless there is a powerful oxidizer (i.e. nitric acid). We simply salt the aqua regia with ammonia ⇦ this on eBay or Amazon [affil links] chlorate to precipitate platinum.

A. I am an amateur refiner; I have been refining gold for several years; recently I have started to recover Pt from AR after the gold is precipitated. I do this by pouring the spent AR into a bucket and add some Al sheet metal. The Al will be absorbed into the solution and will precipitate all other metals in the solution, including a large quantity of Cu. I wash and dry the mud that I get from the AR then boil it in HCl. Wash and dry again then treat with AR. You will now see a quantity of Platinum Chloride (Red Foam) scoop the foam from the top and collect the red mud in the bottom dry and melt. There will be a very toxic smoke to be expelled when melting. Breathing the smoke can result in Platinosis. When melting there will be a lot of residue with small beads of Pt which will accumulate and render a larger bead. This process is a little tricky but it works. Pt melts at about 3000° f. I use Propane and oxygen which only gets to 3500f so I am not able to melt the Pt to a point where it will flow, but I can melt it enough to get very soft and bind together. One can wash the red mud with water; which will result in the Platinum Chloride turning to Platinum oxide and will go from red to black. Just dry and melt. It works for me. don't BREATH THE SMOKE!

A. Dear Sara, Boil the PMG (Platinum Group Metals) that are in HNO3 solution with continued additions of HCl, Boil to almost dryness then add more HCl. After the third time start testing with starch/iodine paper. When all the NOx is gone (TAKE YOUR TIME), reconstitute the solution with water. If you have Pt in solution, recover it first. Use a saturated solution of Potassium Chloride. The Pt will come down as a yellow precipitate K2 Pt Cl4 Filter and wash this with cold saturated Potassium Chloride solution, it is slightly soluble. There are several ways to recover the Pd. The easiest is to ammoniate the solution with concentrated Ammonium Hydroxide in small additions, the Pd will first go to a Pink salt then with a further addition or two this will redissolve. How the Pd can be dropped by slowly adding HCl.At pH 3-4 (HN4)2 Pd Cl6 an orange yellow salt will precipitate. Filter and wash with cold saturated Ammonium Chloride solution, it is also slightly soluble. Save all your wash solutions and test for PMGs before discarding. DO NOT try to melt the salts, huge PM losses. Reduce in solution with Hydrazine, then melt. Bruce

A. Here are three low tech ways of separating copper and palladium:

1) Use Silver.

Silver is above copper, but below palladium, on the electromotive series, so adding silver to the copper/palladium solution will precipitate the palladium and leave the copper in solution. Remove the precipitated palladium and add sodium chloride to the remaining copper solution, and the silver will be recovered as silver chloride. This can be reduced back to metallic silver by various methods. Silver is expensive, and some will be lost in each cycle, so you will have to decide if this method is feasible for you.

2) Use Oxygen.

Use zinc or aluminum to drop both the copper and palladium from solution. Wash this several times and dry. Spread both metals on a non-reactive surface and heat. Copper oxides at fairly low temperatures to copper oxide. Remove this with dilute hydrochloric acid, leaving the palladium.

3) Use ammonium hydroxide.

Add sodium hydroxide to the copper/palladium solution. This produces blue green copper hydroxide, and a dark colored palladium hydroxide. The copper hydroxide is soluble in ammonium hydroxide, leaving palladium hydroxide, which, with heat, will decompose to palladium oxide and finally to palladium.

You can find the physical and chemical properties of these reactions on line, along with such things as oxidation and decomposition temperatures.

No matter how carefully you process the two metals, some copper will always remain, so be prepared to repeat the refining process until you reach the purity which you require.

A. Refining platinum and palladium is a process that requires patience. I recover platinum, Palladium and rhodium from catalytic converters. The process is as follows:

After de-canning the substrate material, I drop the substrates into a drum of hot soapy water and allow them to soak for about two hours (this helps to remove some of the sulfur and excess hydrocarbons). Next, using a water hose and nozzle I rinse the substrates which removes the carbon and sulfur. I then shake out the excess water and allow the substrate to dry for two days. The substrates are then crushed in a small ball mill to a fine powder and I roast these powders in a brick oven at 400 °C, which burns off the remaining hydrocarbons and sulfur. After cooling, the powders are placed into a fermentation barrel and I cover them with a 50/50 mixture of 3% hydrogen peroxide and 32% hydrochloric acid. I add about 100 ml of houshold bleach ⇦ bleach/sodium hypochlorite in bulk on eBay or Amazon [affil links] , cover and then agitate the barrel every few hours for about a week adding bleach every other day. I then filter the liquid into a beaker [beakers on eBay or Amazon [affil links] and heat to a low boil which removes excess chlorine and reduces the solution. After cooling you can precipitate leached PGMs with zinc, keep adding zinc in small amounts until the solution is clear. Your PGMs will precipitate as a black powder. Siphon off the solution leaving the black powders; wash the powders first with water, and then with HCl 32% to remove excess zinc. Afterwards, dissolve the black precipitate in a small amount of Aqua regia and again precipitate the black PGMs with zonce, repeat washes and re-dissolve in AR a second time.

Now you are ready to separate the metals. First precipitate your platinum salts with Ammonium chloride. Filter the yellow salts and save the solution, you can test the solution for palladium with DNG test solution, precipitate with zinc again and wash. Redissolve the palladium in AR and precipitate with sodium chlorate or chlorine gas to produce the brick red palladium salts. Again save the solution.

Your Platinum and palladium salts should be heated to 800 °C to make the sponge (separately, of course). To produce the Platinum and palladium metals from the sponge will require heating to 1800 °C. The metals produced are .999 pure and can be poured into graphite moulds to produce coins or bars, your choice. Hope this helps. Be careful and be safe. always work with a fume hood or outdoors -- the fumes are deadly.

A. You'll have to eliminate the nitric acid from the Pd aqua regia solution before precipitating the red Pd salt with sodium chlorate. This is usually done by evaporating the solution to a syrup, then adding a small amount of HCl. This is repeated until all the nitric acid has been removed, usually 3 times. While evaporating, use low heat towards the end or the solution will splatter.

A. Vivek,

I apologize. I thought you said sodium chlorate instead of sodium formate. Using sodium chlorate is the most common way of dropping Pd. I haven't used sodium formate, but I would think you would still have to remove the nitric first. I may be wrong.

A. Dear vivek Vig,
Palladium dissolves in nitric acid, no need of aqua regia.

A. Use dimethyl glyoxime or hypophospurus acid for palladium precipitation.

"Refining Precious Metal Wastes"
by C. M. Hoke

on eBay or

Amazon

(affil links)

"Recovery and Refining Of precious Metals"
by C.W. Ammen

on AbeBooks

or eBay or

Amazon

(affil links)

? Hi Mehtab. Can you please try your best to phrase your question in terms of the answers already provided? I don't know much about that subject, but it looks like you are re-asking a question that has already been repeatedly answered in pretty good detail more than half a dozen times already. Please try to tell us what you are not understanding. Thanks.

Regards,

A. Hi mehtab.
You have a metal mixture of palladium (Pd), copper (Cu) & silver (Ag). All these dissolve in nitric acid, so dissolve it in nitric acid and then recover it from liquid giving preference to which metal is more in your mixture.

A. Dear shaun,
If possible, you first concentrate your red colour solution nearly half in quantity by volume. Check the pH, add slowly saturated solution of ammonium chloride in it. You will get yellow precipitate of platinum sponge.

Q. Hi, thanks. When you say concentrate I assume you mean heat it up so some of it boils away -- how do I find the pH of what's left? This yellow sponge. Do I then heat this up and turn it into a platinum ingot

A. Dear Shaun,
You have a solution which contains Pt. You heat this solution nearly half meaning if you have 4 liter solution, concentrate by boiling & make up to 2 liters. Then using ph paper sheet you check whether pH is acidic or not. Then add ammonium chloride in it to get yellow precipitate of platinum sponge.

Q. Hi bhupesh, thanks. Great. Now I have a platinum sponge can I put this in a crucible and melt it into a button?

A. Dear shaun,
Put all the yellow ppt in porcelain crucible; burn it at around 850 to 900 °C. It becomes like a gray ash. Then melt that gray powder in ceramic crucible at around 1850-1900 °C; you will get pure platinum.

A. Hi Imran,
I have an answer to your questions. You can use DMG or H3PO4 to precipitate palladium.

A. Hi, mark,
for melting palladium sponge you have to add a small amount of palladium metal before melting process, then slowly add your palladium sponge.
Thanks,

A. Hi armaan,
How did you detect 0.25% Pd still remains? Which assay did you do?
Pd ppt using DMG complex formation.
Thanks

Q. Hi Bhupesh,
I do XRF to check the same.
I doubt if ammonium chloride is precipitating some palladium or XRF is interpreting something false.
From my PT-PD mix dust I have to refine 3 times to get pure PT because every time I get a small proportion of PD in refined PT.