Closed-loop extraction is a form of hydrocarbon extraction wherein the hydrocarbon solvent utilized is kept within a sealed and pressurized system. This “closed” system allows for the recovery and eventual re-use of the solvent in an endless loop of extraction, purging, and recovery. This allows for much lower production costs and safer working conditions.
Both the initial extraction and the purge of remaining solvent from the extract take place within the closed loop system. All of the hydrocarbon solvent utilized can be therefore recovered. As well, the complexity of the closed-loop system itself allows for exact control of temperature and pressure for the creation of butane hash oil (BHO) and live resin.
The closed-loop extraction process is not new and has been used for decades to extract essential oils for things like perfume and food additives. It has only been in recent years that it has become popular in the cannabis industry.
Closed-loop hydrocarbon extraction utilizes a hydrocarbon solvent such as butane, propane, or hexane to wash the trichomes away from the plant surface, leaving only inert plant material behind. The solvent is then evaporated away from the resulting solution, known as “purging”, leaving only the targeted, psychoactive components of the cannabis. All of this is done under pressure in a sealed system which allows for complete recovery of the solvent.
This resulting extract is called Butane Hash Oil (or BHO) and it is used to create a wide variety of products such as shatter, oil, wax, budder, distillate, and sauces such as terpene sauce, high-cannabinoid full-spectrum extract (HCFSE) and high-terpene full-spectrum extract (HTFSE). Closed loop systems are highly suited to the exacting temperature needs of more exotic new extracts like live resin, which involves flash-frozen-fresh plant material as opposed to the more traditional extraction process utilizing dried-and-cured plant material.
A closed-loop extraction system is comprised of a solvent tank, an attached tube for controlled and contained blasting of the plant material, a recovery tank, a refrigerant pump, a recovery pump, a refrigerant scale that measures the weight of the recovery tank, and a vacuum oven for purging the extract solution.