Trying to get the hang of reading my PGM stannous tests. Looking for any insight or opinions on these results to see if they match what I think. I know it's best to test on a swab or filter paper but I couldn't get a great pic that way. Any help is appreciated!
Stumped by Stannous...
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Looks like PdPt in solution. What is the source of the liquid ? Is it acidic ? Does it contain base metals ? What is the original colur ?
What are the chunks in the test dish. Looks like you dropped your pop corn snack in! We need a few more details for a better answer.
I bet either silver chloride or solid stannous "crystals". But more probably AgCl. We will see what is what.
As I do not know original colour, hard to say, but that colour combination I have seen numerous times - PtPd. As SnCl2 in solution is way more sensitive than XRF - we perform drop tests on regular basis.
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Thanks for the replies! haha, the "popcorn" is the salt not fully dissolved in the test dish, that I have been accumulating from boiling down my stock pot after multiple attempts at precipitating platinum palladium and hopefully rhodium from scrap catalytic converters. The liquid surrounding the salt is HCl. Trying to sort through the stock pot and separate the salts into Pt and Pd separately and trying to make sure I am reading my stannous tests accurately. I am hoping that I have boiled out majority of the base metals as removing them is the problem I seem to be running into the most. I appreciate the help and any suggestions for removing base metals is appreciated!
So you evaporated the values in a stock pot down to a crust and solvated that crust with some acid and tested with stannous? Did you cement out the values in the stock pot with copper first?
yes, I boiled the stock pot down to a crust, added HCl to the dried crusts and tested with stannous. I have not cemented with copper, I have read mixed posts about whether or not to cement with copper vs zinc. I have tried zinc in the past but found I still ended up with base metals present in the PGM solution and was unable to successfully separate them. When I tested the crust with stannous after boiling down and adding HCl I did not see much indication of base metals, as far as I am aware, from what I have read, watched and tried.
Zinc will drop all metals.
You really need to use copper with strong agitation and heat.
Thanks for the advice, I really appreciate it!! Once I drop the PGM metals with copper, then I should redissolve in AR (or just HCl maybe?)
and precipitate Pt with ammonium chloride and Pd with sodium chlorate as normal, correct? I've tried multiple times without successfully ending up with a high purity result and really want to get it right this time! I've read Hoke, many posts on this forum and other websites and I know I'm close but haven't quite gotten it just yet! Thank you for the help!
and precipitate Pt with ammonium chloride and Pd with sodium chlorate as normal, correct? I've tried multiple times without successfully ending up with a high purity result and really want to get it right this time! I've read Hoke, many posts on this forum and other websites and I know I'm close but haven't quite gotten it just yet! Thank you for the help!
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I'm no master of the PGMs.
But they are notoriously hard to separate completely.
One of the old ways is Bromate Hydrolysis which can separate quite good, but is quite laboriously and need meticulous control of pH and such.
DMG can be used to separate most of the Pd from the mix, but will need several rounds.
There are also solvent extraction routes that are quite effective.
There are more skilled members than me, to answer these questions, so lets hope they chime in.
But they are notoriously hard to separate completely.
One of the old ways is Bromate Hydrolysis which can separate quite good, but is quite laboriously and need meticulous control of pH and such.
DMG can be used to separate most of the Pd from the mix, but will need several rounds.
There are also solvent extraction routes that are quite effective.
There are more skilled members than me, to answer these questions, so lets hope they chime in.
Just found the "When in Doubt, Cement It Out" post, very helpful information! Yggdrasil thanks for mentioning the use of copper which led me to find that post! Definetly sounds like that may be the best method for what I am trying to do!
Please be aware that refining the PGM salts by dropping with Dimethylglyoxime and ammonium chloride will not yield metallic Platinum or Palladium. You have to (in addition to some purification steps) reduce the salts to metals at the end. Read up on platinosis. It is a serious and can be deadly bodily reaction from exposure to these salts. Be careful.
If you are doing this purely as a hobbyist small scale chemistry project I understand wanting to get to the highest purity possible. But if this is a business venture, consider separating the metals as best as possible without exposing yourself to the salts and sell the relatively high purity metals to a refiner equipped to handle this.
If you are doing this purely as a hobbyist small scale chemistry project I understand wanting to get to the highest purity possible. But if this is a business venture, consider separating the metals as best as possible without exposing yourself to the salts and sell the relatively high purity metals to a refiner equipped to handle this.
I am aware of all those things, safety is definitely a top priority for me, and I understand how to reduce the salts to metals, but I appreciate the thought! Not necessarily looking to make this a business venture, mainly want to prove I can do it!
You would be best served with copper cementation. If you do the cementation rig as described in the post "When in doubt, cement it out", it will work well, but it really needs that bubbling. Agitation is helpful only to some extent.
If you do not have the capability to build one (which is I think very cheap setup with great performance), you can used powdered copper instead of the copper plate or bar. This time you will need good agitation to swirl the copper powder in the beaker well to let it react with PGMs in solution. This time, thick coating of PGM forms on the grains of copper dust particles, but as they have big surface area and aggresive mixing (best on magnetic stirrer) wil break that coating down and liberate fresh metal underneath. With copper dust cementation is usually done after half-hour or so. You can clearly see the copper catching black colouration. And with this procedure (Cu powder, not bar), you want to exclude air as much as possible. Otherwise your copper will quickly react with HCL and air, without doing it´s purpose.
Then you filter the Cu-PGM dust out. Be prepared for very fine particles, so filtration can be a bit tricky with ordinary coffee filters etc. But you can add some flocculent to coalesce the miniscule particles to agglomerates. Or Celite/Bentonite to contain them better, allowing easier - altough more lenghty - filtration.
Also, be aware of a fact, that CuCl2 in solution can and will redissolve finely divided Pd and Pt back to the solution, if not enough fresh surface of copper is available. It is equilibrium reaction.
Maybe I will slightly crush your expectations now, but refining PGM mixtures is hard. Literally hard, in amateur setup. Without fancy liquid extractants, expensive chemicals and most importantly lacking know-how.
From the conventional and well known separation techniques for PGMs, you usually don´t end up with 99+% pure metal/metal salt. Also, these precipitations/selective droppings aren´t complete. With NH4Cl, you will precipitate MOST of the platinum, but if you aim for higher purity, you need to use less NH4Cl - and thus impairing the yield. And from Pd containing solutions, you will always get contamined Pt salt.
https://goldrefiningforum.com/threads/pd-pt-rh-mix-industrial-cat-refining-tips.29773/
read this whole thread. I tried many many experiments and conditions-altering things to separate PtPdRh mixture with aim of concentrating the Rh. You may find this useful
Only precipitant which is quite selective from all "low-budget easy to use" alternatives is DMG. Altough working with higher quantities of it is hard -precipitate is voluminous and in bulk it practically need to be incinerated to get the metallic Pd - and this procedure leads to losses due to evaporation of complex. But for small scale it is sufficient and excellent Pd scavenger - in chloride enviroment you get quantitative recovery of Pd from solution. You can easily get 99% Pd from one DMG drop with thorough washing of the ppt.
Slightly more elaborate procedure for platinum is bromate hydrolysis. Also look it up here on the forum, post from 4metals. And study, understand the chemistry, and be well prepared that these compounds are very harmful to your health - and effects are scarry and irreversible, no cure to this day
Minimize your contact with PGM to necessary minimum. Be safe.
Orvi- Thank you very much for taking the time to send this information to me, in both of your replies. I am grateful for the information you, as well as the other posters, have been willing to share. I also appreciate the concern for safety that is expressed here, I have read much about the dangers of doing this and am very careful!
From the replies and information I have received I think I will give the copper cementation a try. Thanks everyone!
Starting my copper cementation setup and attempt today. No expectations crushed here; I've learned this is much harder than it looks, but I've came quite far, learned a lot, and am not one who's willing to give up easily! Thanks again!Maybe I will slightly crush your expectations now, but refining PGM mixtures is hard. Literally hard, in amateur setup. Without fancy liquid extractants, expensive chemicals and most importantly lacking know-how.
From the conventional and well known separation techniques for PGMs, you usually don´t end up with 99+% pure metal/metal salt. Also, these precipitations/selective droppings aren´t complete. With NH4Cl, you will precipitate MOST of the platinum, but if you aim for higher purity, you need to use less NH4Cl - and thus impairing the yield. And from Pd containing solutions, you will always get contamined Pt salt.
https://goldrefiningforum.com/threads/pd-pt-rh-mix-industrial-cat-refining-tips.29773/
read this whole thread. I tried many many experiments and conditions-altering things to separate PtPdRh mixture with aim of concentrating the Rh. You may find this useful
Only precipitant which is quite selective from all "low-budget easy to use" alternatives is DMG. Altough working with higher quantities of it is hard -precipitate is voluminous and in bulk it practically need to be incinerated to get the metallic Pd - and this procedure leads to losses due to evaporation of complex. But for small scale it is sufficient and excellent Pd scavenger - in chloride enviroment you get quantitative recovery of Pd from solution. You can easily get 99% Pd from one DMG drop with thorough washing of the ppt.
Slightly more elaborate procedure for platinum is bromate hydrolysis. Also look it up here on the forum, post from 4metals. And study, understand the chemistry, and be well prepared that these compounds are very harmful to your health - and effects are scarry and irreversible, no cure to this day
Minimize your contact with PGM to necessary minimum. Be safe.
First attempt cementing with copper...seemed like it worked, but also seemed like it happened a lot quicker than I thought it would. Test with stannous does read pt and pd, remaining solution is clear/very light green and not testing positive for any pgm's. Thoughts on how this looks and the best way to now easily and efficiently separate the pt and pd as much as possible? Redissolve in AR and precipitate with ammonium chloride and chlorine gas as I have in the past? Feel like I've learned a lot the last few days and don't want to mess it up now!
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I don't understand this. You say "stannous does read pt and pd,", but then that the solution is "not testing positive for any pgm's"
Please clarify this for us.
Dave
