Principle of operation
The solid-liquid extraction is a semi-continuous process, coupling distillation with a soxhlet type cartridge containing the solid product impregnated with an active ingredient (solute) to be extracted by dissolution in a hot solvent. The distillation column generates solvent vapors which are condensed; this pure hot solvent feeds the cartridge containing the inert solid and the solute. When the cartridge is full, the solution obtained (solvent and solute) empties automatically by siphoning (leaching) and then returns to the boiler where the solvent is again brought to the boil. The leaching can also be carried out by continuous passage of the solvent or by successive manual draining. The solvent can also be fed in a single "pass" for infusion and the resulting extract is manually withdrawn.