Two types of extraction units may be provided – liquid liquid extraction and solid liquid extraction. It is usually a batch process and involves another liquid (solvent), which aids the extraction process.
The unit consists of heating bath, condenser, reflux divider, pipeline components and valves, along with vessels. The solvent can be fed either from top or bottom depending on specific customer’s requirements.
Units are available from laboratory scale up to 100 litre. These can also be provided with SCADA control for use in R&D and in academic institutes. Further details are provided in the process instrumentation section.
Liquid Liquid Extraction:
This method is used when two liquids cannot be separated by simple distillation process. A solvent of different density is chosen and used to treat the liquid to be extracted. The solute mixes with the solvent and forms an extract.
The remaining liquid passes out as raffinate and is collected. The other liquid too can be recovered from the extract, giving back the original solvent.
Solid Liquid Extraction:
It is used to extract active ingredients from solids using a solvent as a medium. The solid is placed in the extraction vessel through which the pre-heated solvent passes. The solvent is so chosen that the active ingredient gets passes on into the solvent, leaving behind the solid material.
The solvent is then recovered using different techniques such as distillation, leaving behind the active ingredient. The recovered solvent can be reused in the same process.