HAuCl4
Well-known member
Copy pics/videos to data chip / phone / ipad and post from there or email to a trusted forum member. I'm sure Lazersteve or kadriver would not mind posting them for you.Lou said:
"Bromate Hydrolysis" Revisited
- Thread starter RaoOvious
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kadriver
Well-known member
RaoOvious said:Hey kad,
The best would be to do it on impure platinum sponge (after precipitating Pt with NH4Cl and reducing it to sponge),although it can also be performed on whole pgm blacks but that would be inefficient.Regarding the weight of individual metals in the specimen,its not mentioned in the published article of Gilchrist and Wichers.
And removing Pd from mixed bag through Nitric is also severely inefficient,there are ample other options to do the task with minimal hassle.
Hintrop Pt and Pd through orthodox methods and then go after specialized tools to get high purity.
By the way nice to hear from u after so long,whats going on lately?
Hello:
I got a bad case of that nasty flu back in december - put me in bed for a week, and then two more weeks of not wanting to do anything except lay around.
Believe it or not, I still have the concentrated Pd solution that we were working on back in November.
It is just sitting there in a covered beaker. I need to get it going and convert it to sponge so I can get it sold.
I did make a nice chlorine generator using trichloroisocyanuric acid (pool chlorine tablets from Lowes hardware) and hydrichloric acid drip in my fume hood.
I know what to do, just been busy with other stuff.
I'll review the info you sent me and get this Pd going - maybe post some pictures of it.
Thank for your help.
kadriver
kadriver
Well-known member
So, after dissolving in AR (or HCL/Cl gas to avoid nitrosol compounds), drop Pt and Pd via ammonium chloride, sodium chlorate, then incinerate (calcine) to obtain impure sponge, then do hydrolysis on the impure sponge.
I've got a nice Cl2 gas generator, I am thinking of doing an experiment to dissolve mixed PGM blacks (or the impure Pt sponge) in room temp HCl, then bubble Cl2 gas through the mixture to dissolve.
Has anyone ever tried this experiment?
I know HCl/H2O2 and HCl/sodium hypochlorite (bleach) methods. But I have never tried bubbling Cl2 gas.
Since it is new to me, I think setting up the gas generator and making the gas in my fume hood is much fun - for now.
Thanks
kadriver
Edit once to correct chemical name
I've got a nice Cl2 gas generator, I am thinking of doing an experiment to dissolve mixed PGM blacks (or the impure Pt sponge) in room temp HCl, then bubble Cl2 gas through the mixture to dissolve.
Has anyone ever tried this experiment?
I know HCl/H2O2 and HCl/sodium hypochlorite (bleach) methods. But I have never tried bubbling Cl2 gas.
Since it is new to me, I think setting up the gas generator and making the gas in my fume hood is much fun - for now.
Thanks
kadriver
Edit once to correct chemical name
Chlorine-HCl is my favorite method to dissolve sponge because it is clean and fast. I use AR only for bulk materials (clips, springs, wire, sheet).
You want to boil it after all the residue is dissolved, filtering if any insolubles like AgCl or silica are present. At this point, a drop or two of sulfuric is helpful to remove lead. Hopefully it is gold-free as it is much easier a process with more immediate return. If it is not, hydroquinone is indicated.
After you boil, all the Pd(IV) present is converted to Pd(II) while the Pt remains in its highest oxidation state with the Ir. At this point, precipitate the platinum with ammonium chloride. It will be contaminated with Pd, Rh and Ir. The Pd, Rh, Ir containing supernate (largely Pt-free) can then be precipitated as potassium hexachloropalladate with KCl and chlorine gas; the supernatant from that filtration can be treated with dimethylglyoxime and the recovered Pd(DMG)2 complex digested with AR and quickly boiled. I do not advocate for using KCl for platinum at this point, as it is difficult to wash K+ away whereas any residual ammonium chloride from the reduced ammonium hexachloroplatinate is oxidized when the sponge is re dissolved. I do suggest KCl for the Pd salt as this avoids the NCl3 issue in tepid solutions.
The (NH4)2PdCl6 is dissolved in excess conc. ammonia (as is the DMG digest). It will be strongly basic (only way to dissolve pink Vauquelin's salt rapidly) and most impurities will be complexed as ammines. Let this solution stand overnight or simmer it to drive out dissolved excess ammonia. You may see a precipitate form in the near-neutral solution (hydroxides or AgCl). Filter this solution, rinsing with pH8 bicarbonate buffered water. This filtrate is acidified with conc HCl to pH 2-2.5 and the yellow Pd salt is filtered off, rinsed with ice cold 0.05 N HCl/NH4Cl solution until the filtrate runs completely clear. The Pd diammine chloride is treated with cold, concentrated ammonia and the (hopefully clear) solution is filtered (this removes any rhodium and Pt traces). This Pd is precipitated again as above, filtered/washed and the salt is treated with sodium formate at pH 3.5-5 in DI water at 65 C, and will quickly and quantitatively reduce. It should now be 99,9+ pure. All filtrates should go in for cementation (or IX if you have it) and be reprocessed with the next lot, after a good incineration and water leach to remove ammonium/potassium cations.
Return now to the ammonium hexachloroplatinate. Reduce it thermally or with zinc, giving it a quick rinse and being sure the acidic filtrate is colorless. Redissolve this platinum (syrupizing if using AR or the Rh may cause problems) and prepare for the hydrolysis. We will talk about that over the phone.
Hope this helps!
You want to boil it after all the residue is dissolved, filtering if any insolubles like AgCl or silica are present. At this point, a drop or two of sulfuric is helpful to remove lead. Hopefully it is gold-free as it is much easier a process with more immediate return. If it is not, hydroquinone is indicated.
After you boil, all the Pd(IV) present is converted to Pd(II) while the Pt remains in its highest oxidation state with the Ir. At this point, precipitate the platinum with ammonium chloride. It will be contaminated with Pd, Rh and Ir. The Pd, Rh, Ir containing supernate (largely Pt-free) can then be precipitated as potassium hexachloropalladate with KCl and chlorine gas; the supernatant from that filtration can be treated with dimethylglyoxime and the recovered Pd(DMG)2 complex digested with AR and quickly boiled. I do not advocate for using KCl for platinum at this point, as it is difficult to wash K+ away whereas any residual ammonium chloride from the reduced ammonium hexachloroplatinate is oxidized when the sponge is re dissolved. I do suggest KCl for the Pd salt as this avoids the NCl3 issue in tepid solutions.
The (NH4)2PdCl6 is dissolved in excess conc. ammonia (as is the DMG digest). It will be strongly basic (only way to dissolve pink Vauquelin's salt rapidly) and most impurities will be complexed as ammines. Let this solution stand overnight or simmer it to drive out dissolved excess ammonia. You may see a precipitate form in the near-neutral solution (hydroxides or AgCl). Filter this solution, rinsing with pH8 bicarbonate buffered water. This filtrate is acidified with conc HCl to pH 2-2.5 and the yellow Pd salt is filtered off, rinsed with ice cold 0.05 N HCl/NH4Cl solution until the filtrate runs completely clear. The Pd diammine chloride is treated with cold, concentrated ammonia and the (hopefully clear) solution is filtered (this removes any rhodium and Pt traces). This Pd is precipitated again as above, filtered/washed and the salt is treated with sodium formate at pH 3.5-5 in DI water at 65 C, and will quickly and quantitatively reduce. It should now be 99,9+ pure. All filtrates should go in for cementation (or IX if you have it) and be reprocessed with the next lot, after a good incineration and water leach to remove ammonium/potassium cations.
Return now to the ammonium hexachloroplatinate. Reduce it thermally or with zinc, giving it a quick rinse and being sure the acidic filtrate is colorless. Redissolve this platinum (syrupizing if using AR or the Rh may cause problems) and prepare for the hydrolysis. We will talk about that over the phone.
Hope this helps!
Kad,
I hope you would further enjoy in your new endeavors. Yup you can dissolve Pd,Pt nd minutely Rd through your chlorine bubbling apparatus. I would suggest if you have a mix bag of PGM's(largely Pt,Pd,Rd,Ir) then dissolve them as per your favorite methods except its favorable to avoid any salt formation(as with hypochlorite),denoxx or dechlorinize, concentrate your pregnant solution to 1gm per 5ml, then precipitate using NH4Cl for Pt(along with Pd,Rh,Ir impurities), filter efficiently so that no supernatant solution remaining in your filtrate, reduce with dilute Hcl/Zinc nd convert to impure sponge "Feedstock for Hydrolysis".
As with filtered solution bubble chlorine or chlorate or chlorite, filter until precipitate is clear from supernatant remaining solution (scavenge this with zinc to add to the impure Pt sponge for Hydrolysis).
Remaining can be found regarding Pd in already discussed material.
Good luck and have fun.
(edited out text lingo Butcher)
I hope you would further enjoy in your new endeavors. Yup you can dissolve Pd,Pt nd minutely Rd through your chlorine bubbling apparatus. I would suggest if you have a mix bag of PGM's(largely Pt,Pd,Rd,Ir) then dissolve them as per your favorite methods except its favorable to avoid any salt formation(as with hypochlorite),denoxx or dechlorinize, concentrate your pregnant solution to 1gm per 5ml, then precipitate using NH4Cl for Pt(along with Pd,Rh,Ir impurities), filter efficiently so that no supernatant solution remaining in your filtrate, reduce with dilute Hcl/Zinc nd convert to impure sponge "Feedstock for Hydrolysis".
As with filtered solution bubble chlorine or chlorate or chlorite, filter until precipitate is clear from supernatant remaining solution (scavenge this with zinc to add to the impure Pt sponge for Hydrolysis).
Remaining can be found regarding Pd in already discussed material.
Good luck and have fun.
(edited out text lingo Butcher)
HAuCl4
Well-known member
Is there a problem with using the TCCA directly in the metal reactor to avoid the chlorine gas rig?.
Yes there is a problem, cyanuric acid is produced as a byproduct. The less to filter the less you worry about entrapping values by entrainment. TCCA is the best way to make Cl2 safely (way better than other methods) and is easily controlled.
kadriver
Well-known member
The gas rig I have was relatively inexpensive and easy to set up. Plus its fun because its new to me.
I will get some photos and post them here when I chlorinate some palladium solution to make ammonia soluble (NH4)2PdCl6.
The most expensive piece was the equalizing funnel at $53 with free shipping.
Here is a picture of it (24/40 ground glass connections). Bought it on Ebay
http://www.ebay.com/itm/221173823773?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649
kadriver
I will get some photos and post them here when I chlorinate some palladium solution to make ammonia soluble (NH4)2PdCl6.
The most expensive piece was the equalizing funnel at $53 with free shipping.
Here is a picture of it (24/40 ground glass connections). Bought it on Ebay
http://www.ebay.com/itm/221173823773?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649
kadriver
Attachments
Nice tool,
I appreciate you posting that, if I understand how it looks like it would work, you could have an acid in the chamber open the valve to drip acid into the vessel below, the small gas tube on the side would allow gases from the reaction to pressurize the space above the acid chamber, to assist in pushing the acid out through the valve, even into a pressurized vessel below the valve.
I appreciate you posting that, if I understand how it looks like it would work, you could have an acid in the chamber open the valve to drip acid into the vessel below, the small gas tube on the side would allow gases from the reaction to pressurize the space above the acid chamber, to assist in pushing the acid out through the valve, even into a pressurized vessel below the valve.
kadriver
Well-known member
Thats exactly how it works. The other funnel i was using would drip the acid in an irregular fashion.
The equalizing funnel completely eliminates the irregular flow and makes controlling the amount of gas produced a snap!
kadriver
The equalizing funnel completely eliminates the irregular flow and makes controlling the amount of gas produced a snap!
kadriver
I just had to get one, its too cool for gas generation.
HAuCl4
Well-known member
Thanks Lou. What is 'entrainment' exactly.Lou said:
I guess it depends on the feed that one is processing.
For gold dust, sponge after inquartation, or atomized karat scrap, mixing the TCCA with the metal, and dripping the HCl works extremely fast and clean. Since one has to filter and wash the AgCl cake anyway, it makes sense.
I prefer to use a separatory/addition funnel with a Telfon valve in the place of the glass valve. Teflon is less likely to stick and way less likely to break.
Steve
Steve
kadriver
Well-known member
I have never used a funnel with a teflon valve.
When I first started using the sep funnel with the glass stop it would stick something terrible and cause problems with getting it shut off quickly.
Then I bought some dow high vac grease and lightly applied to to either end (being careful not to get the grease near the hole in glass stop valve).
Now it operates nice and smooth.
I have not broken one of the glass ones - yet.
Do the teflon stops need grease like the glass ones do?
kadriver
When I first started using the sep funnel with the glass stop it would stick something terrible and cause problems with getting it shut off quickly.
Then I bought some dow high vac grease and lightly applied to to either end (being careful not to get the grease near the hole in glass stop valve).
Now it operates nice and smooth.
I have not broken one of the glass ones - yet.
Do the teflon stops need grease like the glass ones do?
kadriver
Teflon is naturally slick due to it's low coefficient of friction. The Teflon valves have a couple rubber (?) o-rings that require a slight lube to keep them from drying out from chemical exposure, but for the most part, no lube of the valve.
Steve
Steve
Please be careful using PTFE (teflon) as a stopcock material! On hot solutions, especially with separatory funnels, the PTFE will expand and cause the joint to leak. The o-rings are usually Viton, which is generally pretty chemical resistant, but they are not made for aqua regia.
The only thermoplastics suitable for long term hot aqua regia exposure are PVDF, PTFE, FEP, PFA. Polypropylene and even CPVC will fail. Polyesters/amides and other condensation polymers are wholly unsuitable for strong acid or base. This is the grease we use for joints/o-rings, or anything getting really hot. I use it on my firearms too. http://www.vacuumoil.com/krytoxgrease.htm
Entrainment occurs when values get stuck in hydroxide cakes by adsorption and are not expeditiously or easily removed without compromising the purity of the solution. To me, it means the gradual collection of values in waste streams by attrition.
I'll post some examples of a pilot bromate hydrolysis. Here is preparing the feed...
when I'm back off my other computer I'll post the re-dissolve and some hydrolysis pictures.
The only thermoplastics suitable for long term hot aqua regia exposure are PVDF, PTFE, FEP, PFA. Polypropylene and even CPVC will fail. Polyesters/amides and other condensation polymers are wholly unsuitable for strong acid or base. This is the grease we use for joints/o-rings, or anything getting really hot. I use it on my firearms too. http://www.vacuumoil.com/krytoxgrease.htm
Entrainment occurs when values get stuck in hydroxide cakes by adsorption and are not expeditiously or easily removed without compromising the purity of the solution. To me, it means the gradual collection of values in waste streams by attrition.
I'll post some examples of a pilot bromate hydrolysis. Here is preparing the feed...
when I'm back off my other computer I'll post the re-dissolve and some hydrolysis pictures.
Attachments
necromancer
Well-known member
Lou said:
how is it you log on to the forum ?
I can get on via proxy but can't post attachments. I was at my hotel to post last time.
Rao, that scale weighs in troy ounces, so it is closer to 3700 grams. That yellow powder is calcined at 850 C, then the chunks are ground up and redissolved, and then diluted to ~55 g/L and pH brought up to 0.5.
It's possible to just do the hydrolysis several times to rid of other transition metals, but that is more time intensive.
Rao, that scale weighs in troy ounces, so it is closer to 3700 grams. That yellow powder is calcined at 850 C, then the chunks are ground up and redissolved, and then diluted to ~55 g/L and pH brought up to 0.5.
It's possible to just do the hydrolysis several times to rid of other transition metals, but that is more time intensive.
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