I’ve been reading about extractive metallurgy in my spare time for the last 18 months. Finally I get to try it. The other day I rediscovered the solvent power of molten sodium carbonate. At 1000 C it dissolves porcelain crucibles. Luckily an hour at 1000 C wasn’t enough for a catastrophic failure, just some melt through on the bottom.
Somehow, seeing your reaction vessel glowing yellow-orange (on purpose) is deeply satisfying and awe inspiring.
At these temperatures, the notion of acidic and basic conditions needs to be recalibrated for low temperature chemists like me. Irrespective of the crucible, I did digest my sample and convert it into a yellowish meteorite shaped like a flattened cupcake.
Carbonate fusions are used to release metals from silicate matrices. Molten carbonate hydrolyzes the silicate matrix and renders the resulting mass amenable to attack and dissolution by mineral acids. Platinum is the preferred crucible material of construction. I have such a Pt crucible. It’s beautiful.
Lamentations on Chemistry 
I want one! Maybe a link to a catalog would be nice, so I can put a pic up in the lab?
who comes up with this? Na2CO3 at 1000C?? certainly not something I would have envisioned being useful.
A: Only the mind of Th’Gaussling.
Actually this approach to materials processing has been around since at least the days of the alchemist. Carbonate fusion is one technique in the realm of fluxing. Fluxes are additives that, when melted with a mineral or a metal, can extract certain components from the product mixture. In this case, Na2CO3 depolymerizes silicate networks to release whatever metals may be present. A flux may alter the phase separation of the slag phase more cleanly, often by decreasing its viscosity.
Why does the carbonate not just decarboxylate to Na2O and CO2?
Hey Goob,
I’m not sure that it doesn’t to some extent. I don’t have a good answer yet.
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