Wizzard
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GIft from local TV recyclers- I have stuff to share!
A local TV recycling plant has been vacuuming the phosphor area from CRTs and collecting it, and storing it- I will be getting an amount of this
(likely a few coffee tins) to play with- It has REEs, Iridium, and plenty of other things (but much Pb).
Anybody interested in a sample for themselves? I'll ship it out at just shipping and material cost (glass vial preferred, some foam and a small box).
It's all oxides, a powder. Pictures as soon as I get my own sample.
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tetrahedron
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what a convenient way to get rid of their most hazardous waste
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Wizzard
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I'm only taking a bit  He's just been holding onto most of it, and he'll take
back whatever I no longer want. I know there is plenty of lead, but I'd like to try extracting the Ir and the assortment of REEs, even if I can't
isolate them from one another easily.
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SM2
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Nah, good intentions I'm sure. Funny, when we want to give some shit away, we put it on the curb, and put a price on it. Sure 'nuff, it gets stolen
when it's dark. Put a sign which says "FREE", and you have a tough time getting rid of it.
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blogfast25
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@wizzard:
It'd be nice to see how you get on with separating stuff from that...
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plante1999
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Well I made a short research and the main interesting content are:
Cadmium
Barium
Rare earth
I don't know if I want to play with mixed unknown composition stuff. At least I know whats in cinnabar.
I never asked for this.
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bfesser
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I'm surprised they don't want to sell it to a rare earth elements refining company... unfortunately, most seem to be in <a
href="http://en.wikipedia.org/wiki/Rare_earth_element#Global_rare_earth_production" target="_blank">China</a> <img
src="../scipics/_wiki.png" />. Couldn't the phosphor be re-used as-is in home-made <a href="http://en.wikipedia.org/wiki/Cathode_ray_tube"
target="_blank">cathode ray tubes</a> <img src="../scipics/_wiki.png" />—producing only one color near white?
[Edited on 7/9/13 by bfesser]
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Poppy
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Was wondering, what are those electron cannon devices coated of, since TV tubes do not have a fairly amazing vacuum...Or thats not included at all?
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12AX7
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Electron guns are either nickel or stainless steel, nothing impressive. Inside of the main bulb is aluminized; there may be some barium from a
getter, which is usually placed at the end of said electron gun.
Mainly, what keeps the amazing vacuum is an amazing amount of tedious work sealing it up, baking out impurities, and sucking the holy hell out of it
before sealing. 
Tim
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Wizzard
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@12AX7- That, and non-volatiles in the tube
Here's what I expect in the tubes (percentages):
Source: http://biblioteca.cdtn.br/cdtn/arpel/adobe/Art-01_Carlos_AMo...
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watson.fawkes
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Quote: Originally posted by bfesser  | | Couldn't the phosphor be re-used as-is in home-made <a href="http://en.wikipedia.org/wiki/Cathode_ray_tube" target="_blank">cathode ray
tubes</a> <img src="../scipics/_wiki.png" />—producing only one color near white? |
Maybe. It depends on how much recrystallization happens in the recovery process. If it's simply mechanically removed, then it would
likely still glow. It wouldn't be a particularly pure white, because as a collection of relatively narrow-band phosphors, it wouldn't mimic the
black-body spectrum for white light particularly well.
I can't say I know very much about the details of phosphor function, but I do know enough to have some gauge of my ignorance. Many colored phosphors
work as fairly pure crystal structures with small amounts of dopants. The dopants cause dislocations and strains on the crystal lattice, changing the
electronic structure of the main components. This is why you see things like Eu-doped-Y show up in phosphor compositions. As for the details, it's
some solid-state quantum mechanics that I'm not very intimate with.
<!-- bfesser_edit_tag -->[<a href="u2u.php?action=send&username=bfesser">bfesser</a>: fixed
broken image(s)]
[Edited on 7/9/13 by bfesser]
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watson.fawkes
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Most electron guns have a thin-film
coating on them to reduce the work function, as compared to that of the base metal. I don't recall what the common ones are, but I do recall that for
the guns used in electron microscopy, the coating has a large effect on the emission rate, and that the lifetime of such gun elements is predominantly
about the lifetime of the coating.
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ElectroWin
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if it's unknown composition, then it's hazardous waste; but i could use some barium carbonate or other barium salt, from a Canadian source preferably.
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12AX7
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Yes, the cathode itself is different materials -- typically a tungsten heater, insulated with a layer of aluminum oxide, inside a nickel cathode,
coated with a "rare earth oxide", which I believe was mainly alkaline earths, but I haven't read much about what is likely a trade secret hush-hush
subject. (Common cathode materials today include LaB6, but AFAIK these are newer developments and were never used in consumer equipment.) The
electrode structure is mainly shiny metal like I said, along with some glass rods to stabilize them.
Tim
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