VeritasC&E - 3-9-2022 at 12:57
What is the best way (as most energy efficient + fastest / most convenient) way to dehydrate (not completely but hemihydrate state, thus with
sufficient temperature control) a bunch of CaSO4 (~10Kg)?
Is microwave a suitable method?
Can microwave form arcs with CaSO4 (or with metal salts)?
If I skip temperature control and dehydrate it completely, can I just leave it stored in a closed container with adequate amounts of H2O thrown in
hoping that it will homogenise to produce a uniform mass or hemihydrate after a few weeks/months?
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[Edited on 3-9-2022 by VeritasC&E]
Sulaiman - 3-9-2022 at 18:02
There are a couple of things to consider when heating gypsum (dihydrate) to plaster (hemihydrate),
Gypsum and plaster are poor thermal conductors - spread thinly on a tray/hot surface
micro-pockets of steam burst, emitting very fine dust - disposable oven/kiln or a big clean up
Water added to bulk anhydrate or hemihydrate forms a solid lump of dihydrate.
Keeping moisture OUT is required.
PS probably the cheapest and easiest way to get small quantities of the hemihydrate is to buy plaster 
('plaster of Paris' is the purest type - I believe)
[Edited on 4-9-2022 by Sulaiman]