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.