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12AX7
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On a larf, I wandered across the platinum pages in Brauer. On H2PtCl6:
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Since the last traces of nitric oxide are very difficult to remove, finely divided Pt may also be dissolved in hydrochloric acid through which Cl2 is
bubbled (or nascent Cl2 may be generated in the solution itself by carefully adding HClO3 or H2O2 to it).
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Aha! Then I may have dissolved much of it after all.
Adjecent also lie two formulas for electroplating the stuff, one containing a large amount of sodium citrate.
Tim
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12AX7
Post Harlot
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Oh yeah- I remembered doing something more with this.
After washing the substrate several times with tap water, I reduced the chlorine-rich solution with iron metal. After the acidic solution dissolved
the iron, I was left with a black precipitate and a green solution (now turning yellow as the iron oxidizes back to ferric). This should be precious
metal. I would be suprised if there is a gram of the material, but it's not zero.
Tim
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Aqua_Fortis_100%
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Tim, was you catalytic converter very old?
Im planning to acquire at least one to make similair experiments to get Pt for platting. But since I live in a good sized city, trying to get from
scrapyard will probably be cumbersome, since is difficult to get it because the people that work on this will arrive much earlier than you and all
that rest is nothing  maybe I can be wrong in this..
According to one patent I've see a long time ago (attached..If you want I can give a translation), to get high yeilds in recovery (>99%), would be
good to first crush and ball mill the catalytic ceramic them heat strongly in presence or air/O2 to burn out any carbon that it contain (it will
reduce the yields if is left since PGM are adsorbed and ppt on its surface) them treat by cheap means, that were discussed here:
Cl2 + aqueous HCl suspension of powdered catalyst
H2O2 + aqueous HCl suspension of powdered catalyst
chlorate + aqueous HCl suspension of powdered catalyst
bleach + aqueous HCl suspension of powdered catalyst
Attachment: BRPI0505796A.pdf (368kB)
This file has been downloaded 1733 times
"The secret of freedom lies in educating people, whereas the secret of tyranny is in keeping them ignorant."
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blogfast25
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A quick question about this homemade aqua regia: I have only 32 w% HCl, what ratio to mix this with 38 w% HNO3 to obtain (a presumably weak
form of the real deal) aqua regia? What safety precautions need to be taken into account during mixing and use? 
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12AX7
Post Harlot
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| Quote: | Originally posted by Aqua_Fortis_100%
Tim, was you catalytic converter very old? |
~20 years. Might be a gram or two in it.
Tim
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blogfast25
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Well, a test with 1:3 (by volume) HNO3 (38 w%)/HCl (32 w%) shows much higher reactivity with homemade Ti than 32 % HCl alone. To be fair here I used a
piece of Na nitrate boosted Ti thermite metal, not K chlorate boosted. It dissolves rather briskly at RT, compared to chlorate Ti in pure HCl. Pure
(99.8 w%) Ti also reacts slowly with pure RT HCl, so it'll be interesting to see what this conconction will do to it. This "poor man's aqua regia" may
prove to be the solution (pardon the pun) to my sampling problems...
The solution is yellowish, no Ti<sup>3+</sup> is being formed, so I assume some NOCl is present in solution.
I'm also testing HCl 32 w%, saturated with NaNO3, but that just started. I might try 38 w% HNO3 saturated with ammonium chloride too. 
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blogfast25
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Well, well, well. A few hours after I started the 'homemade aqua regia' test, that solution has now completely changed to a brown, turbid colour, with
lots of dark grey matter (powder) at the bottom and NO<sub>2</sub> in the head space (I use a piece of kitchen towel to plug the conical
flask). The shed reeks of NO2. The metal is still reacting quite vigorously with the acid(s) and the solution must be about 50 C (122 F).
The NaNO3 saturated HCl on the other hand, has almost no effect on the chlorate titanium.
[Edited on 19-5-2008 by blogfast25]
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Aqua_Fortis_100%
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Tim, only 1 or two grams for an old catalytic converter(?!?!) How much the ceramic on it weights before you dipped it in the acid tank ? I have
heard that the usual amount of PMG is about 2-5g for each kilogram of the ceramic stuff. Still, older catalytic converters would have even more PMG.
"The secret of freedom lies in educating people, whereas the secret of tyranny is in keeping them ignorant."
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12AX7
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I did not weigh, and I probably wouldn't be able to minimize mechanical losses enough to make that a reliable measure.
I don't think I got much if anything out of the solution...
Tim
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blogfast25
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The homemade 'AR' (80 ml) has now stopped reacting with the (1.9 g) nitrate Titanium. The solution is a urine-like yellow but there's also lots of
insoluble residue which I'll try and isolate. I'm now repeating the test with a larger volume of acid (200 ml for 3.9 g of metal).
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