Samuel, first, PGMs, especially platinum, are extremely hazardous when in solution or their dried salts. We have lost too many members who have succumbed to this hazard. Please exercise the highest level of laboratory hygiene when working with them.
As you've probably found, the market for PGMs is much smaller than for gold or silver, and they have higher expenses, lower payouts, and higher minimums. It's not that they're trying to cheat anyone. It's just that the costs of doing business in that market are much higher.
Since you say you are new to this, how do you know you have 4 troy oz of PGMs? What is the source? How have you processed it? I'm not trying to be difficult, but a prospective buyer will want to know. There are members here who might be interested if you can provide more information.
We have a member here named Lou. His username is Lou. He deals with PGMs. I don't know what his minimums or fees would be like, but it may be worth sending him a PM.
Dave
Dave, I appreciate you for reaching out and bestowing your knowledge upon me. I am well aware of the dangers, risks working with PGMs in their respective salt forms and the requirements of lab hygiene to be safe, I guess I am not considered new anymore to refining (or maybe I still am?) Since I have been learning and practicing for a bit over a year, so I am at the point where I feel comfortable of my basic understanding and capabilities as far as refining goes.
I am sure that it's (over) 4 troys oz of PGMs (not in salt form) in metallic form as mixed PGM black powder. I know this because I followed the chemistry and obtained an expected and (somewhat) predictable result. I obtained the PGMs by first taking catalytic converter ceramic (honeycomb) substrate that was bearing the PGMS and placing them in several 5 gallon buckets, with lids that sealed as to prevent, or at least minimize the levels of potentially (or actually inevitably) escaping chlorine gas that is an unavoidable hazard or this particular process.
I then proceeded to fill the buckets with the quintessential hydrochloric acid, usual concentration (x= <32% HCL) until the fluid level just covered the material, then over the course of anywhere ranging from 3 weeks to 2 months, I would slowly add my source of chlorine, usually either by way of calcium hypochlorite granules ( pool shock), or broken pieces of the big blue pool shock tabs, the name of the active ingredient alludes me but i think it starts with a "Triaz- something or rather", I generally preferred to use this one as i believe that it produces more chlorine than the calcium hypochlorite (which is about 50% conc. As opposed to the other which was around 90ish%) by weight.
I repeated this step either every other day or sometimes every few days, or when I feel that the chlorine had likely dissipated significantly enough to justify adding more chlorine without frivolous waste, then would give her a good shake after sealing the buckets back up.
When I feel like the cats were leached for an appropriate time, I would carefully filter the solution, which was now well impregnated with PGMs, so that it was not cloudy, but clear orange, brownish orange, whatever variation, then I would use chunks of (sometimes some shot I made) zinc to cement out the PGMs as the respective black powder form, finely divided.
After black powder settled, I would then carefully decant the now clear and barren solution through a coffee filter for catching any black powder that may have spilled over, then I would put the waste into my exclusively PGM stock pot, to let any further black powder I may have missed settle even more, then I would give it one pass with more HCL to ensure most of not all the zinc has been put into solution, then rinse a couple of times with water, then lastly dry out the powder, then weigh it up (that's how I got my 4 troy Oz numbers).
NOTE: there were other instances where I was able to successfully separate the platinum from palladium as there respective salts, calcined, and turned into metal, however I did have some difficulties with a few things; one thing I was having trouble with was after I got the PGM black, I for whatever reason could not get the what I believe was probably platinum to go into solution, it would seem to dissolve the palladium and maybe a little of platinum and the bulk of the powder would still be sitting down on the bottom and this was happening even with me boiling it in AR for a few hours.
For whatever I was doing wrong, I could never get it all into solution on my second dissolution, so I had to settle with just doing the precipitation and separation from the first dissolution, which I did without any problems for the most part. I even tried it with the acid peroxide method without any luck, although I was only using the 3% peroxide I had immediately available, maybe therein lies my problem? So that's what I have experienced so far in my endeavors. I hope I have done well to answer any questions, but I'm sure still there is something I am probably forgetting to mention...
Oh yes, in case anyone else is wondering, the answer is yes; I did and would run the cat material more than once, twice, even three times, to get as much as possible outta them.
And even after that, I still saved all the processed materials as I feel confident in the likelihood that there are some values that I didn't get out, such as namely the rhodium as well as what platinum and palladium I couldn't get.
Since I haven't quite learned how to target and recover the rhodium ( or least a way in which I have the necessary supplies and for which I don't yet have a firm grasp of my understanding of the process), so I don't feel comfortable yet to try recovery of it yet.
So if anyone is interested in purchasing it, I am very open and happy to discuss it with whomever, just feel free to inquire. Also, thanks to ANYONE who has the patience to read through the novel I just wrote. I appreciate you and your time. Also thanks to anyone else who is willing to help me with the insight and invaluable wisdom shared.
