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deltaH
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Colour looks a lot lighter than before or is that just the bright sunlight?
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blogfast25
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Finally got round to reading all of this thread. I've gotta say I'm quite sceptical of some of deltaH's assumptions. I guess we'll find out soon now.
The main problem is that we simply don't know whether the raw sample contains any Pt at all: that's a poor starting point for testing an extraction
method. 
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aga
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Hang on in there and Keep the Faith dude.
There's no tried-and-tested 'method' here.
Dangerous and Unreferenced Speculation is deltaH's speciality.
All he needs to find out one way or another is some unsuspecting idiot who will try the crazy ideas out.
Any numbskull will do, just one ... who ...
DOH !
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deltaH
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Cucurbit
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Looks promising!
Just make sure the instructions for the molecules are written on the inside of the bucket so they can read it 
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deltaH
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aga, have your electrodes arrived yet? Is the concentrate dry?
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aga
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No electrodes yet.
The remains of the sludge got washed out of that crappy bucket a couple of days ago and stuck on a tray. Almost dried.
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deltaH
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Thanks for posting the pic, it looks very promising, can't wait for the next stage! Hope the electrodes arrive soon.
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Chem Rage
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Quote: Originally posted by aga  | No electrodes yet.
The remains of the sludge got washed out of that crappy bucket a couple of days ago and stuck on a tray. Almost dried.
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Looks deliciously appetizing! 
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aga
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50p a slice plus postage.
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Fleaker
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Unfortunately, even wavelength dispersive XRF will have trouble seeing the PGM content unless it is very close to the road and in a concentrated
pocket.
If I tasked with the analysis of road side dirt (which is funny, because it's probably one of the few weird things I have not processed in doing this
PGM chemistry as a living), I would start with a nickel sulfide collection and go from there first with base metal sulfide removal with dilute HCl,
filter on a Whatman 42, ash, reduce Pd/Rh w/ borohydride, dissolve residue in microwave and run on my ICP-OES.
Hell, on 100 kg of dirt with sufficient NiS you'll probably end up with enough platinum to see 
Neither flask nor beaker.
"Kid, you don't even know just what you don't know. "
--The Dark Lord Sauron
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The jersey rebel
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| Quote: Originally posted by aga | Depending on rainfall, getting your hands on the dust might be economically viable.
Rain washes stuff into the sewers/storm drains.
Periodically these need to have the silt cleaned out, which is a service that the town council generally pay for, as the waste (in the UK at least) is
classified as 'contaminated' due to the oils & tars from the tarmac.
The waste companies have to pay to dispose of the silt.
If you could work out how to profitably process the silt (and dispose of the residues) you'd simply offer a free disposal service to the waste
companies, and they'd collect/transport the silt to your facility for free. |
So the silt will probably contain far more PGM's since the oils and tar mixture sort of act like clay in a gold mine. The best process I can think of
is to first heat it to pyrolyze the oil and tar. Then take the ash and mix it up with an oxidizer such as KNO3 to strip the carbon out. Both of these
steps also serve to aggregate the particles a bit. Then put the ash in a furnace along with a bit of copper to act as a collector metal. Some flux
(NaCO3/borax/MnO2) is then added and it is heated to about 1200 celcius with occasional stirring with a graphite rod. Then the copper alloy is
electrorefined and the anode slimes are saved. Melt it under an arc and then you have the final product unless you are looking for extremely pure
platinum which will require a lot more work
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aga
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There's a 1 litre pot of the NaOH treated roadside dirt hanging about at the back of my fume hood.
Still not found any high temperature fire bricks yet, but the plan is to follow thru on deltaH's suggested process.
The Arc is ready and temperatures in the Shed are dropping from the normal Summer 45 C (just 30 C today) so things may start happening soon ...
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MeshPL
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The real problem is that to achieve 1800C you need really good fire bricks. Typicall grog fire bricks melt at 1780C. I'm not sure what typicall
insulating fire bricks are made of, but those which are not insulating are usually made of said material. Maybe expanded perlite, but this will also
will likely be insufficient.
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aga
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I got some grade 28's on order, rated to 1,560 C.
(apparently grade 32 goes up to 1760 C, but there were none to be had)
Around that will be other 'normal' firebricks, which IIRC are rated to 1,300 C.
Will it Blend ?
Dunno. Gonna find out when they arrive.
Edit:
The specs say they are made of 'aluminosilicate' in varying proportions, and then have been set in a foam kinda structure.
[Edited on 17-10-2016 by aga]
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yobbo II
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Some nice (terrible expensive) bricks here
http://www.ebay.co.uk/itm/REFRACTORY-BRICK-HIGH-TEMPERATURE-...
How do you intent to heat this thing?
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aga
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Gotta go with what i'm gonna get.
Heating, as stated, will be an electric arc. Possibly 2000 C plus. No idea.
Those inadequate (for the purpose) bricks, stick welding rig and some graphite rods.
Dunno until i try it, then will probably still not know exactly how hot.
Mucho Calor. Muuuuncho.
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densest
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IIRC a hydrogen-oxygen torch is hot enough to melt platinum. A 250 cu ft. tank of each might cost $US 50. There's a reason not to use acetylene but I
can't remember it. I think the idea of a solvent metal is good. Iron leaches gold, copper leaches silver.
Is there any reason why the dried material must be basic?
If the colloidal material only floats in a basic environment, one way to concentrate it would be to take the murky basic suspension and acidify it.
Hypothetically a precipitate would form concentrated in the desired Pt + SiO2
One thought, though: SiO2 + NaOH -> sodium silicate which is more or less soluble. If that reaction occurs, the PGMs will precipitate. The reaction
is normally slow. The extremely large surface area would speed it up a lot.
It would help a lot to determine what the composition of the rest of the road dust is. Rock dust from the gravel in the road surface? Brake shoe dust?
Asphalt? Rust? Cigarette butts? Chewing gum? Tire rubber? Rust/steel powder from the belts in the tires? Glass fibers from tire belts?
I'd recommend decanting and acidifying quickly.
[Edited on 3-11-2016 by densest]
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aga
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Not a clue.
I guess i got to zap the NaOH dirt mixture.
I think it's Fear that has stopped me doing it earlier.
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