about platinum precipitation!

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serkanSSI said:
Hello,

how to crash platinum in AquaRegina , I could not find the stages about the start and application in the forum.

Regards

View attachment 54314
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Welcome to the forum.

Everything is here. But Platinum metal salts are very toxic.
What experience do you have with Precious Metals and Chemistry?

Your descriptions are so out of character that I guess you have little experience.
It is called Aqua Regia, not AquaRegina.
And it is called precipitate not crash, crashing is an accident and you do not want accidents in a lab.

We want all newcomers to read a book called "Refining precious metal wastes" by C.M. Hoke
https://goldrefiningforum.com/phpBB3/viewtopic.php?f=54&t=19798This will give you the basic chemical processing around refining.
Then we want you to study the section for safety and treating waste.
 
Boil down to a syrup, acidify with hydrochloric, boil, acidify with hydrochloric add a little hydrogen peroxide whilst just below the boil and then add saturated ammonium chloride until the solution is very pale yellow, cool, filter and marvel at the fine yellow powder. If you omit the boiling stage the yield will be less but not by much. Cement the filtrate with iron, zinc, tin or magensium powder add this residue to your next aqua regia dissolution batch.

Please do treat Pt salts and solutions containing platinum with the upmost care. I know of at least a dozen people who have had adverse reactions from the salts of platinum. They range from minor skin issues to suspected anaphylaxis. I would not attempt this unless you have a firm understanding from the book above.
 
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serkanSSI said:
With these four materials after filtration in the second stage? What is the mixing ratio?
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The best way to cement any Precious metal is thick Copper Bus bar or other thick Copper.
Usually we recommend Copper, the others will drop any other metals in solution.
Copper will only drop the precious metal and Cadmium and Mercury if it is there.
But for PGMs there has to be strong stirring from the beginning or there will be a layer of PGMs that pacify the Copper.
 
Yggdrasil said:
The best way to cement any Precious metal is thick Copper Bus bar or other thick Copper.
Usually we recommend Copper, the others will drop any other metals in solution.
Copper will only drop the precious metal and Cadmium and Mercury if it is there.
But for PGMs there has to be strong stirring from the beginning or there will be a layer of PGMs that pacify the Copper.
Click to expand...
I would only slightly correct that Cd won´t be precipitated by copper. It has similar electrode potential as iron. Mercury will of course cement on copper.
 
serkanSSI said:
Hello,

how to crash platinum in AquaRegina , I could not find the stages about the start and application in the forum.

Regards

View attachment 54314
Click to expand...
We need to know more. What else is in the solution regarding base metals such as iron or copper, is gold present ? Any other PGMs ? What was the source of the material ? What is rough concentration of Pt ? Is there any residual nitric acid in the solution ?

Ammonium chloride is typically used to precipitate ammonium hexachloroplatinate salt. But it has it´s own limitations. You need to have nicely de-NOx-ed solution, as Platz pointed out. Otherwise platinum drop would be less efficient. For recovery use, you would need to add high excess of NH4Cl to accomplish good efficiency - leftover HCL also help to minimize solubility of this salt.

If you have hydrolyzed solution of platinum (not enough HCL to stabilize fully chlorinated PtCl6 2- complexes), it is possible nothing would drop. In case of this happens, you need to add fresh HCL and let it sit for prolonged time (sometimes days) for Pt to fully precipitate as platinate.
Cementation of leftover solution after the drop - if there aren´t much base metals, simplest and most effective is to add zinc to precipitate platinum. Iron also work well, but deposit of platinum would be thick and dense, so occasional addition of HCL would be necessary to loosen this deposit from the iron surface, enabling further reaction.
Platinum salts are hazardous, building up the allergy unnoticed for long time, until it´s too late. Outside professional setup, you cannot rule platinosis out by any means. Be mindful of this, wear PPE all the time, do every manipulation of platinum salts in the fumehood and also protect your neighbors and co-workers.
 
orvi said:
I would only slightly correct that Cd won´t be precipitated by copper. It has similar electrode potential as iron. Mercury will of course cement on copper.
Click to expand...
My bad.
I did not check before posting, but seemed to remember it was claimed earlier.
Thanks again Orvi.
 
serkanSSI said:
Hello,

how to crash platinum in AquaRegina , I could not find the stages about the start and application in the forum.

Regards

View attachment 54314
Click to expand...
What are you planning to process?
Scrap or ore?

When you have read and studied the required book and sections.
You need to be able to test for the precious metals.

Stannous is our go to testing method, so make yourself some Stannous.
Then either buy or make a standard Gold solution so you can test that the Stannous works as intended from time to time.
 
So, I have been having some issues in my recovery and or refining of pgms. Mainly I cannot get anything (the yellow platinum salt) to drop with ammonium chloride.
The material is from various catalytic converters, the ceramic substrate is in chunks and also fine powder.
I have gotten the pgms into solution by two different methods,
One being with aqua regia and the other being, of course, hcl and bleach leaching, which is also the bulk of my material, the aqua regia batch is relatively small, as i did the smaller chunks and powder ceramics with it.
.
With the hcl and bleach method, I had already successfully obtained the pgm black powders by means of cementing out with zinc.
Afterwards I had dissolved the pgm black powders back into solution using hcl and 3% hydrogen peroxide this time .

I have gotten to the point where I felt confident enough to attempt to precipitate the platinum with ammonium chloride that I had made myself with 10% ammonium hydroxide from ace hardware and hcl added together and evaporated to obtain the white crystals of ammonium chloride.

I then proceeded to boil down a small test run of my aqua regia solution to attempt to denox with out sulfamic acid (I couldn't aquire any), by boiling down to a syrup like consistency and rehydrate with both water and more hcl a few times until I felt like I probably successfully denoxed.
I had also boiled down a test batch of my hcl and peroxide solution but not quite to a syrup, just to concentrate a little.

I had tested with stannous chloride on both solutions and both showed originally only positive for platinum with orange color, however after attempting the platinum drop with a saturated solution of ammonium chloride (roughly 30 grams in roughly 200ml of h20) I did not get any from what I could tell is am obvious canary yellow platinum precipitate. In fact nothing appeared to happen at all.

But, when I test with stannous again, my aqua regia test batch showed negative for all pgms and my hcl and peroxide solution I think I now showing positive for palladium but no yellow platinum salt appeared (I will post pictures next post).

So I am baffled by this and I am getting frustrated by this point. I know I must have screwed up somewhere at this point but I cannot figure out where.
If anyone has any insight or wisdom to share with me, I would love to hear it and I would really appreciate it.
And if there are any relevant details I am omitting here please feel free to ask me questions.

Thanks,
-Samuel.
 
16827935720114708365408754198831.jpg
This is the stannous results, no.3 is from my hcl and peroxide batch, which has also leaked in to no.1 I will rinse off and retest and post results of my other solutions as well
And in no.4 is from my aqua regia solution, notice the negative for pgms.
 
samuelbaldwin010 said:
View attachment 56808
This is the stannous results, no.3 is from my hcl and peroxide batch, which has also leaked in to no.1 I will rinse off and retest and post results of my other solutions as well
And in no.4 is from my aqua regia solution, notice the negative for pgms.
Click to expand...
First and foremost, drop the spot plate.
Use cotton buds or pieces of paper.
Much less liquid used and much easier to interpret.
I have not used Ammonia Chloride myself, but I think you need to make sure it is in its highest oxidation state first.
Bubble Chlorine through it it or add Sodium Chlorate.
Then Ammonia Chloride.
 
16827945235053229319477192922462.jpgthese are the hcl and peroxide solutions. Test batch is on the right and bulk on the left. I think i accidentally precipitated the red palladium salt. This is because i accidentally added some of the pool shock chlorine stuff I had instead of the hcl I was trying to add. That's what happens when you put both next to eachother. I will do a retest and post results.
 
samuelbaldwin010 said:
View attachment 56810these are the hcl and peroxide solutions. Test batch is on the right and bulk on the left. I think i accidentally precipitated the red palladium salt. This is because i accidentally added some of the pool shock chlorine stuff I had instead of the hcl I was trying to add. That's what happens when you put both next to eachother. I will do a retest and post results.
Click to expand...
What kind of protective gear are you using?
Have you already studied the safety section and dealing with waste?
 
samuelbaldwin010 said:
View attachment 56810these are the hcl and peroxide solutions. Test batch is on the right and bulk on the
samuelbaldwin010 said:
View attachment 56810these are the hcl and peroxide solutions. Test batch is on the right and bulk on the left. I think i accidentally precipitated the red palladium salt. This is because i accidentally added some of the pool shock chlorine stuff I had instead of the hcl I was trying to add. That's what happens when you put both next to eachother. I will do a retest and post results.
Click to expand...
A
left. I think i accidentally precipitated the red palladium salt. This is because i accidentally added some of the pool shock chlorine stuff I had instead of the hcl I was trying to add. That's what happens when you put both next to eachother. I will do a retest and post results.
Click to expand...
The color is not right. Check if crystals dissolve easily in water
 
samuelbaldwin010 said:
I have gotten to the point where I felt confident enough to attempt to precipitate the platinum with ammonium chloride that I had made myself with 10% ammonium hydroxide from ace hardware and hcl added together and evaporated to obtain the white crystals of ammonium chloride.
Click to expand...

Don't feel bad....I tried that home made ammonium chloride several years ago and it didn't work for me either. I think the Pt solution has to be at a certain concentration.... not sure.
 
Yggdrasil said:
What kind of protective gear are you using?
Have you already studied the safety section and dealing with waste?
Click to expand...
First off, thank you for your timely and prompt reply.
I am using rubber gloves( the really thick yellow ones for washing dishes and such..) and/or regular nitrile gloves (depending if I am dealing with nitric at the time), I don't have a fume hood, nor do I have anywhere to put one or I would have just made one by now, so I am doing everything outside.

Sometimes I will use a respirator mask if there's quite a bit of fumes, but mostly I just try to stay up wind of the fumes. since I have also read somewhere that the masks don't actually help much, if at all, anyway, but in case it does help, I will wear it as an extra precaution.

As for the wastes I have made, I have my stock pots separated by ones that have contained gold plus non ferrous base metals, gold plus ferrous base metals,
Pgms plus ferrous, pgms plus non(no metal) ferrous base metals.
I have been just storing them in plastic jugs for now,

My plan thus far is to: after I process stock pot(s) and recover the precious metals (if there are any present), I will then cement out whatever copper there is with either zinc or aluminum, then neutralize acidic solutions, and lastly dispose of solutions in a environmentally friendly and legal manner.

For filter papers, stannous chloride test q-tips, etc. I have them being stored separately in the same manner (categorized) as my stock pots, when I get enough saved, I will process as per Hoke.

And that's pretty much it. Hopefully this answers any questions and hopefully i am using acceptable practices here.

-Samuel
 

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