A lithium mining expert doubted use of NaCl to extract Li from clays so I did a shallow Google search: Source: Extracting Lithium from Clays by Roast-leach Treatment By Joan T. May, D. S. Witkowsky, Don C. Seidel They used the same Nevada clay deposit Elon mentions. However, they used potassium chloride and were disappointed. But sodium is more electro-positive reactive and smaller than potassium. This means the extraction rates seen in the original report should be higher using sodium chloride: Ionization energy (1st) Li - 520.2 kJ/mol Na - 495.8 kJ/mol K - 418.8 kJ/mol Chemistry suggests sodium chloride would have been a better choice over potassium chloride in the paper. Still, there are other factors such as identification of whatever the Li is linked with in the clay. If I were investigating, I would use a mass spectrometer and electrophoresis to separate the ore molecules and identify the lithium concentrated compounds. This may lead to insights for more effective Li extraction. So @tochatihu, close enough? Bob Wilson
ionic radius and hydrated ionic radius are not the same. Latter one would seem to be the one to look at here. Unfortunately I find sources saying Na+ is smaller than K+ and also the opposite. Clays are all alumino-silicates (AFAIK) but they do differ in arrangements, so one cation indeed might be a better displacer than the other for reasons beyond hydrated ionic radius. 'Roast' suggests structures are (needfully) altered before the Na or K arrive, so native crystal structures might not mean much. do not know what you are going to do with mass spectrometer and electrophoresis. books dot google is not on my access list, so ??? If recent and authors have emails, why not ask them?
With some effort, I was able to extract a PDF of the 1979 report: What I wanted to collect were even small samples of the lithium compounds to see if we can figure out what the Li is bound to. Knowing the molecular mass helps reduce the candidates. It is possible there is a broad range of molecular masses involved but we still want to know what is there. If a small sample(s), micrograms(?), can be collected, zap them with a powerful light source and analyze the spectrum to identify the elements. Given the less than 1% lithium in the ore, my first thought was to replicate some of the Manhattan project separation techniques. Happily, some enrichment can be achieved by separating the SiO{2} that is ~50% of the clay and possibly some of the others. I found a second source claiming HCL can treat the clays and make a LiCl compound that vaporizes at 900 C. But heating bulk ores with less than 1% lithium content to 900 C takes a lot of energy. Even after taking out the 'low hanging fruit', the easily separated, this remains a hard problem. Bob Wilson
