Cyril R wrote:
There will also have to be some sort of recirculation line at the top to go down again, to let the gas take another pass and improve reaction effectiveness. Even graphite is going to suffer from fluorination by F2. But if you have a gas phase you can use Monel or similar metal that forms protective NiF2, CuF2 layers. This should work. I think there will be a problem if you have both a very oxidising F2, PuF6 environment, combined with liquid salts because the liquid salts will dissolve the NiF2, CuF2 layer. Frozen salt can work for the main fluorinator tube but not so well for smaller process piping and such. Frozen salt also likely isn't gas tight, so that you still have to make the entire thing out of Monel. But that's ok, it's quite small.
The recirc gas will be F2, it doesn't want to be bubbled through the liquid. Can we inject the F2 above the liquid and have a "sealing" liquid that is lighter than the salt that separates the liquid from the protective layers?
OR if we do vacuum distill first then could we tolerate losing the Ni&Cu that is right at the surface level? It does two things: a) adds Ni&Cu to the liquid - but if we did vacuum distill first then the fluorination the remainder isn't of high value and so we are just adding a bit of Ni&Cu to the waste stream b) removes a bit of Ni&Cu from the vessel - as long as the removal rate leaves us with an acceptable lifetime this is ok.
Quote:
One promising route to take, that is both protective and gas tight, is to use noble metal coatings. Some noble metals don't form fluorides (these have a much lower free energy of formation than even carbon tetrafluoride). Noble metal coatings on carbon steel are likely cheaper than Monel too, and don't take up as much space as a frozen wall of salt so can be used in the process lines (such as the recirc line).
This does sound promising.