FrankMartin
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CaO from Ca(OH)2
Hello. Has anyone used microwaves for the reaction:
Ca(OH)2 -----> CaO + H2O ?
My intention is to produce quicklime for solvent drying, from the readily-available Ca(OH)2.
The Ca(OH)2 theoretically decomposes at about 500degC
I want to avoid muffle furnaces and molecular sieves.
Frank
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12AX7
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Without liquid water, it may not heat very well. You'd have to try and see if it works. Note: run the microwave with a glass of water in the corner
as a load. Microwaves with no load are known to overheat and blow up... And yeah, boiling water isn't exactly the thing you want when dehydrating,
so... all the more reason not to.
You might just as well use a (sacrificial) stainless bowl over the stove; a gas stove will reach that temperature with ease, though you may want some
insulation to ensure it goes to completion.
Tim
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hissingnoise
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| Quote: | The Ca(OH)2 theoretically decomposes at about 500degC
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Hmmm! Wiki gives the temp. at 825°C!
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FrankMartin
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The 825degC refers to limestone (Ca(CO3)2), Slaked lime decomposes at a much lower temp.
I tried to decompose some Ca(OH)2 but the microwave itself heats up, so I stopped. Before/after weighing showed no result at all.
This shows a small home-made furnace that might be suitable.
http://www.youtube.com/watch?v=en4yhzLuD9A
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Bert
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Or you could use a MICROWAVE KILN
This guy made one, and did a " how to " video
[Edited on 16-4-2014 by Bert]
Rapopart’s Rules for critical commentary:
1. Attempt to re-express your target’s position so clearly, vividly and fairly that your target says: “Thanks, I wish I’d thought of putting it
that way.”
2. List any points of agreement (especially if they are not matters of general or widespread agreement).
3. Mention anything you have learned from your target.
4. Only then are you permitted to say so much as a word of rebuttal or criticism.
Anatol Rapoport was a Russian-born American mathematical psychologist (1911-2007).
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hissingnoise
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| Quote: | | ]The 825degC refers to limestone (Ca(CO3)2). |
Ooops! Yes, I don't know my carbonate from my hydroxide . . . ?
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macckone
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This should be easily doable. It basically requires insulation
(flame proof) and a special crucible (carbon/ferrite). The
one pictured in the first link is a commercial variety where
the two materials are one unit.
The crucible absorbs the microwaves and produces the heat.
The microwaves themselves don't have much to do with the
reaction since the crucible absorbs them.
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WGTR
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Although you don't want to use an electric furnace, it is probably the easiest and cleanest way of doing this. Here's a thread
detailing different electric kiln designs. In the same thread at least a couple of people made their own quicklime.
https://www.sciencemadness.org/whisper/viewthread.php?tid=26...
Have fun.
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