Platinum Refining Practice with a Pure Pt Coin

[kadriver]

here is the link to part2

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=52&t=26319

kadriver

 

[cuchugold]

I admire your patience and dedication.

Another way to do it, that produces acceptable results with fewer losses, is to cement the pure Platinum from the syrupy H2PtCl6 solution with very pure magnesium or zinc. It bypasses the intermediate ammonium salt processing completely. Very suitable to the small refiner.

Another: One professional refiner, keeps boiling the purified (after hydrolysis without bromate!) H2PtCl6 till it is a red solid, then heats it up in a tube furnace to 350 C and converts it to brown PtCl2, with HCl and Cl2 evolved as gases (and due scrubbing). Then reduces the PtCl2 to Pt using a stream of hydrogen. This is probably the route to the purest metal, but it requires more equipment and proper technique.

Others keep using the ammonium chloride route... because they can!.

Welcome to the ~<0.1% club of chemists that have processed Platinum!.

 

[kadriver]

Another way to do it, that produces acceptable results with fewer losses, is to cement the pure Platinum from the syrupy H2PtCl6 solution with very pure magnesium or zinc. It bypasses the intermediate ammonium salt processing completely. Very suitable to the small refiner.

This sounds very useful, I'll have to give it a try.

I don't want to become a professional Pt refiner, just want to be able to process the small pieces of Pt that I have, and do my stock pot so I can shoot a video.

Thank you for those useful tips.

kadriver

 

[cuchugold]

Another way to do it, that produces acceptable results with fewer losses, is to cement the pure Platinum from the syrupy H2PtCl6 solution with very pure magnesium or zinc. It bypasses the intermediate ammonium salt processing completely. Very suitable to the small refiner.

This sounds very useful, I'll have to give it a try.

I don't want to become a professional Pt refiner, just want to be able to process the small pieces of Pt that I have, and do my stock pot so I can shoot a video.

Thank you for those useful tips.

kadriver

This will hurt many, but here it goes anyway. I hope you can swallow it, because I'm on the move to hopefully bigger and better things. These are only comments on HOW you may improve your technique, if you learn WHAT to do. Only after suffering the initial garbage refining advice, you are ready. I think you've suffered enough.

1-To dissolve, QUICKLY, the Pt alloys (of which you will only encounter 3 or 4, not 5, because the commercial alloys are generally binary, and Osmium does not exist for you or me). But never mind, because it applies to ore too. You must find a metal to alloy it with. Similar to what you do with inquarting gold. Hoke speaks of lead, zinc, silver. There are more, like gold karat (spoken by 4metals), by deduction pure gold, and also aluminum, and a few others. Pick your poison: To dissolve QUICK, instead of the 7-8 hours (or never), you must alloy with something. Ir and Ru (common hardeners) in jewellery cannot alloy with lead. Therefore, they separate from lead, in manner similar to solvent extraction but at 1,100 C. This is my chosen path, usually. In a passing manner, as if casual, this is described by Hoke, when she speaks about the Acton refinery, and also somewhere else in the same book. Lead fusion paper by Gilchrist posted in the books section by Jimdoc, I believe.
2-Now you are with an alloy. Depending on your alloy, the process follows. Your main task is to get rid of the other metals and get the Platinum in a relatively pure solution. Usually nitric acid is used, except for Aluminum and karat gold. (4metals has posted clearly his process. If you follow the recipe you get your turkey cooked).
3-Once you get the platinum powder dissolved with weak aqua regia, or preferably a non-nitric acid process, such as chlorate + HCl, or HCL + H2O2, or HCL + Cl2, then you go to bromate hydrolysis (or bromate-less hydrolysis). Use 4metals method, or Lou's without Bromate. If there were 100 Platinum refiners in the world there would be 500 methods of "Hydrolysis". Pick one. It doesn't matter, really. You will soon do it YOUR WAY.
4-After you filter out all the hydroxides (maybe 2 filtrations are needed, for a fast and a slow , 1-2 punch hydrolysis, which I favor), then you cement with magnesium. Why not zinc?. Because impurities in magnesium are usually calcium and sodium, which AID your cementing, and not heavier metals like lead in zinc, which TWART your aims of pure metal.
5-After you get your cemented platinum, you can compress into a pellet, re-refine it, etc, etc. No need to go to intermediate salts. You pack it into a pellet or pellets, and leave it like that, waiting for your customer needs. After that, you can forge it hot, like Wollaston did, for the purest product. Seek the paper. After it is in a continuous metal button you may melt it. If you have a big quantity, and access to an induction vacuum furnace you can melt it there.

The rest of the Platinum group metals are interesting, but not from any financial perspective, except if you can get a LOT of them continuosly.

That's off the top of my mind, if you think you know better, then you are probably right, as "it depends". I hope to bring discussion and comments into the matter, but I know I will likely get none. Maybe a few insults. In any case God bless the Platinum Gods, and William Hyde Wollaston, my hero.

 

[Lou]

I already told Kevin over the phone that adding some salt to the evaporated syrup will prevent overdrying to PtCl2.

This is practice for refinery sponge as he said. What we call 995 Pt that goes for hydrolysis to 4N. Then it can be melted in lime or Y2O3(7%)ZrO2 crucibles. Lime cleans up any W/Mo/Ta/Nb/Ti/Sn etc.

I melt Pt in quantity with induction but the best cleaning method for certain impurities is an oxidizing flame in a lime furnace. One can see how clean of basemetala the Pt is by how it looks. Also, any oxidizing flame can be used. Sooty flames can carbide the Pt and any reducing flame can cause interactions with certain crucible materials.

 

[cuchugold]

Thanks Lou!. After cleaning those non-PGMs, what would the typical assay show as impurities?. Maybe hydrolisis can be skipped completely for most applications. :idea: