testimento
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CaSO4 > Ca2S > SO2?
Calcium sulphate, as known as gypsum, can be used to make sulfur dioxide with roasting(blowing hot, 1200-1300C air into), and I'm not quite sure if
this is appliciable with carbon because of the very high melting/decomp. point of the CaSO4, but this works fine with other sulfates like NaSO4 KCO4,
etc. This produces sulfide of the salt, which could be released as hydrogen sulfide or sulfur dioxide by different methods. The roasting method is
quite challenging because most of the materials will give up just about that themp.
Im interested in, what would be the easiest way to convert sulfide salt into SO2? One method involves adding an acid, which generates hydrogen sulfide
and this would be simply burned to yield sulfur dioxide, but I think it's a bit of a waste of good acid, and I was thinking of other ways involving
high temperatures or reductions with cheap and easily available chemicals.
Intention is to use the SO2 with V2O5 to produce SO3 for sulfuric acid. CaSO4 is sold at fraction of a buck in large sacks and that would yield a
reasonable source for sulfuric acid, where none is available OTC.
And for minors and beginners, hydrogen sulfide is a rotten-egg smelling gaseous poison comparable to hydrogen cyanide which will kill on sight, and
other chemicals involved are also very dangerous and the rest are not suitable for human consumption any better. 
[Edited on 25-7-2013 by testimento]
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bfesser
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Show us that you've done some research on your own, and cite sources for the claims you're making, otherwise this will be moved to
Detritus. You seem to have complete disregard for the scientific method not to mention common forum etiquette.
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watson.fawkes
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Quote: Originally posted by testimento  | | Calcium sulphate, as known as gypsum, can be used to make sulfur dioxide with roasting(blowing hot, 1200-1300C air into) |
Wrong. You can liberate sulfur dioxide from gypsum, but not this way.
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AndersHoveland
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There is no easy way to oxidize the sulfide without it getting oxidized to sulfate.
I am not sure, but perhaps if you heated the CaSO4 with sulfur, thiosulfate might form, and then add dilute hydrochloric acid...
2 CaSO4 + 3 S --> 2 CaS2O3 + SO2 ???
CaS2O3 + 2 HCl --> CaCl2 + S + H2O + SO2
[Edited on 25-7-2013 by AndersHoveland]
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ElectroWin
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the reaction requires extreme heat, yellow-to-white hot if i recall correctly:
CaSO4 + 2C --> CaS + 2 CO2
and must be protected from exposure to air, so put a lid on it.
then, cool and dunk in H2O:
CaS + 2 H2O --> Ca(OH)2 + H2S
i'm trying to remember whether you need to lower the pH to drive that forward.
and then burn the H2S that comes off:
2 H2S + 3 O2 --> 2 H2O + 2 SO2
at this point,
you might want to dry it before passing it over your vanadium+O2
whew! lots of steps
[Edited on 2013-7-25 by ElectroWin]
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AndersHoveland
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Wikipedia mentions the reaction:
3 CaSO4 + CaS → 4 CaO + 4 SO2
I would imagine it takes place at around the same temperature that calcium sulfite decomposes at, still quite high.
http://www.google.com/patents/US4102989
Yes, you do.
CaS is only slightly soluble in water, though there is some small equilibrium. To release the H2S, acid is needed.
Something else to remind the chemists here, S2- ions actually do not exist in water. When dissolved in water, Na2S forms a
fairly basic solution, containing OH- and HS- ions. The second hydrogen does not ionize off very easily. CaS has such a low
solubility because of its high lattice energy, since it contains +2 charged cations and -2 charged anions.
[Edited on 26-7-2013 by AndersHoveland]
[Edited on 26-7-2013 by AndersHoveland]
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testimento
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I was thinking a setup for this. I'd heat the CaSO4+CaCO3 up to 800-900C with charcoal and then insert quartz tube into the pot and inject air heated
up to 1300C that is preheated at the coal bath and afterburned with nichrome wire. I saw a similar patent regarding this process that uses
vortex-style reactor with petroleum fuel burners to bring up the temp, then scrub the products wih cold water and get the SO2.
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Fantasma4500
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well, of what i remember back in time when i wanted to get a hold of CuO and i didnt look much into the carbonates, i tried decomposing CuSO4*H2O into
CuO, and SO3
SO3 would be better for H2SO4 but certainly a bigger health risk
also if you manage to flood a room with SO3 you might want to take some time off, because its heavy so its not that easy to get out --- ammonia is
wonderful stuff
i believe the actual decomposition of CuSO4 after it has gone into anhydrate was below 1200*C, making is suitable for what you want..?
CuO you can probably sell in bulk anyways
the problem with SO3 is that you might also want to invest in teflon tubing etc
perhaps copper wont take much damage from it?
SO3 + H2O > H2SO4
if you want a simple more controlled way to make pure SO2 or well at least pure enough for the purpose, why not
S > SO2 + H2S
the H2S wont stay in solution of what i know, or well perhaps it might as there might be alot of free oxygen in H2O2 (assuming this would also be
useful SO2 + H2O2 > H2SO4)
it could potentially act as ''dessicating'' the oxygen out of the H2O2
creating more sulfur..
2H2S + O2 > 2S + 2H2O
perhaps NaHCO3 + SO2 wouldnt be ruined by the H2S from sulfur, and then form sodium thiosulfate?
please be careful with SO3 its awfully choking
using a gas mask with filter along with a wet piece of cloth infront of the filter airintake might make you more or less 'SO3-proof'
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ElectroWin
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| Quote: Originally posted by Antiswat |
the problem with SO3 is that you might also want to invest in teflon tubing etc
perhaps copper wont take much damage from it?
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actually i expect copper to corrode, if hot, as:
SO3 + Cu --> CuO + SO2
since hot conc. H2SO4 does attack copper.
by the way,
there is presently a world wide glut of elemental sulphur, due to petroleum industry. so begin with that, to get your SO2?
[Edited on 2013-7-30 by ElectroWin]
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Fantasma4500
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indeed, corrosive gasses is one thing, but hot corrosive gasses can open up for new reactions, or well just speed stuff up if they do happen at more
standard temperatures..
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phlogiston
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As an alternative to the problematic heating step, you could ignite a mixture of calcium sulphate and aluminium or magnesium powder. This reaction
proceeds rapidly and yields an enormous amount of heat, quite comparable to thermite mixtures.
I am not quite sure of the exact reaction, but the following is suggested in various places and seems plausible.
3CaSO<sub>4</sub>+8Al ---> 3CaS+4Al<sub>2</sub>O<sub>3</sub>
No doubt, however, you will end up with a mixture of several compounds in various ratios, and some of the sulphur may escape (as
H<sub>2</sub>S (from moisture), SO<sub>2</sub> .
Crushing the residue and dumping into acid should yield H<sub>2</sub>S which can be burned to make SO<sub>2</sub>.
You'd have to be quite desparate for SO<sub>2</sub> to go this route IMO though. Sulphur should be available pretty much everywhere as an
fungicide for algricultural uses. Burn it --> clean SO<sub>2</sub>
[Edited on 29-8-2013 by phlogiston]
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bfesser
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| Quote: Originally posted by bfesser | | Show us that you've done some research on your own, and cite sources for the claims you're making, otherwise this will be moved to
Detritus. You seem to have complete disregard for the scientific method not to mention common forum etiquette.
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And yet, not a single reference or show of effort. Out of respect to the others who have contributed to
this thread, I won't move it to Detritus outright. [closed]
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