It seems like everyone is talking about using ethanol for large scale processing operations. I am starting to wonder if this is really the best route and wanted to describe an alternative approach. This idea came about when I was investigating nanofiltration for solvent recovery, and learned that hexane can be sent through a membrane up to 3x faster than ethanol.
The process would go something like this: use room temperature heptane to extract cannabis, perhaps in a centrifuge like used for ethanol, modified for all materials to be compatible with hydrocarbons. A centrifuge should actually recover more effectively for hydrocarbons because of their lower viscosity and polarity. Or extraction could be done in a continuous fashion, maybe with a screw-type extractor.
Then the product can be dewaxed and desolvated at room temperature with membrane systems. You could perhaps even decarb the plant material in advance of the process, cut the solvent down to a equal ratio with oil, and move directly into a crystallization reactor with no need for distillation. Considering the great leaps made in the CRC thread, it seems scrubbing + membrane dewaxing would likely give a product pure enough to crystallize without trouble.
This would pretty much eliminate all need for heating and cooling in the process, cutting operating expenses. Heptane will not pick up any water, so there would be no need for reproofing and recovered solvent could be recirculated back into extraction immediately. It could even be used to extract freshly harvested plant material without drying first.
Has anyone implemented something like this?