06 Aug What is Hydrocarbon Extraction?
Hydrocarbon extraction is a method used to extract cannabinoids such as tetrahydrocannabinol (THC), cannabidiol (CBD), and terpenes from cannabis plant material. It has become a widely popular extraction method for cannabis refinement in recent years, due to its low cost, efficiency, and extraction quality, as compared to alternative methods.
The hydrocarbon extraction technique involves the use of certain hydrocarbons like propane and butane – these materials act as solvents, which, when combined with plant material, strip desired chemical compounds (such as cannabinoids) out of plant material. This isolate is then further refined through a number of other methods. Highly concentrated extracts can be used to create cannabis oils, shatter, glass, hash, wax, and other products – these extracts contain little to no hydrocarbon residue when the commercial extraction is performed properly.
What Are Hydrocarbons?
Hydrocarbons are a classification of organic compounds consisting of carbon and hydrogen. They are formed from the compression of animal and plant remains over long periods of time, and are pulled from porous rocks such as sandstone, limestone, and shale, where they pool and concentrate. The most common hydrocarbons include butane, propane, hexane.
In addition to being a common fuel source, some hydrocarbons are powerful organic solvents. Organic solvents are substances capable of dissolving or dispersing other substances – they most commonly used in natural food flavorings, soybean oil, vegetable oil, and many other food products which are consumed on a daily basis.
Butane vs. Propane
Butane is a popular solvent in the cannabis world. It’s a non-polar, Class 2 flammable liquefied gas), with a low boiling point ( 31.1°F). In cannabis extraction, this is important because it allows for the cold-boiling of any leftover solvent from the concentrate, which preserves temperature-sensitive terpenes. It’s often popular to blend butane with propane when extracting, to create a gas mixture that will strip additional terpenes and purge more efficiently than butane alone, since the boiling point of propane is so low (-43.6°F).
When used in isolation, propane extracts slightly different ratios of cannabinoids and waxes and can be purged easily without affecting the integrity of the terpenes. However, because propane exhibits different traits than butane when used as a solvent, it’s more common to find extraction equipment that relies on a blend of both butane and propane.
A Brief History of Cannabis Extraction
Extraction of cannabis is a relatively simple process that people have used for centuries. There are ancient historical records of people consuming cannabis extracted products like tea, hash or tinctures. Hash, cannabis resin, was first mentioned in records in the 12th century in Egypt and arrived in Europe in the 18th century. People traditionally ate hash; smoking did not become common until the 16th century.
The science behind cannabis extraction has greatly evolved since then. However, the reason people extract cannabis is simple and has remained unchanged even after centuries. The final product is much more potent than the fresh plant, and it contains more of the desired compounds. Therefore it is easier to know the dosage.
Hydrocarbons like propane and butane have been used since the 1970s for food extractions. Hydrocarbon extraction can produce a finished product with approximately 70-90% cannabinoids. Technologies used for extraction have acutely advanced as the demand for cannabis products quickly increases. Legalization of cannabis has catalyzed innovations in extraction methods. New solvents are sought after in order to achieve the highest quality products.
Cannabis concentrates are making huge gains in popularity, including oil. Cannabis oil is widely popular among cannabis users because it is convenient, consistent, and more concentrated. One of the fastest-growing subsets of concentrates is CBD oil. There is scientific evidence that CBD can reduce seizures in epilepsy patients and can reduce anxiety, inflammation, and chronic pain. It may also be useful in treating insomnia.
The Benefits of Hydrocarbon Extraction
Hydrocarbons are the most commonly used extraction solvents – and they provide the best results. In fact, hydrocarbon solvents have been safely used in the food-processing industry for more than 50 years.
The main advantage of hydrocarbon extraction is the large number of products you can create from a single extraction without any further refinement. And, while this is some concern over the use of hydrocarbons like butane or propane in the processing of products that are ingested, the U.S. Food and Drug Administration (FDA) recognizes butane and propane as safe ingredients, within certain limits. Some of the major advantages to using a hydrocarbon as your extraction solvent:
- Efficiency & Throughput: Hydrocarbons have a cycle time of only 60 minutes, while supercritical CO₂ can range anywhere from 6 all the way up to 10 hours. Not only that – hydrocarbons are capable of operating at exceptionally low temperatures, which means greater preservation of the quality and unique characteristics of cannabis material.
- Versatility: While it’s common for hydrocarbon extraction equipment to utilize a blend of butane and propane (generally with a greater percentage of the former), it’s not a requirement that multiple hydrocarbons are used. Each solvent produces a different result, and these differences can be utilized to refine a large variety of end products.
- Yield: Butane extraction can yield between 14% to 30% by weight. By comparison, CO2’s extraction yield will often top out around 8%. This means less wasted plant material.
- Preservation: Hydrocarbon extraction preserves the plant’s flavor, aroma, terpenes and flavonoids. Unwanted elements, like chlorophyll, are not extracted from the plant. Ethanol extraction can damage the plant’s flavor and aroma, thus requiring the product being masked with flavoring or scents.
- Safety: Despite the belief that hydrocarbon extraction is in less safe, butane and propane extraction equipment operate at relatively low pressures (not exceeding 300 pounds per square inch). This makes them much safer for the operator and the equipment that other high-pressure techniques. Also, all major hydrocarbon solvents are regarded as generally safe to use by the FDA.
Properly maintained professional hydrocarbon extraction equipment has almost no risk, it’s simply a reality that when using a flammable solvent like butane, the entire processing laboratory should be in compliance.
Breaking Down The Hydrocarbon Extraction Process
The hydrocarbon extraction process is incredibly efficient and results in a high-quality end product. The main stages of this process are as follows:
- Assess Quality of Plant Matter: When developing a cannabis distillate, it’s essential that the initial plant matter has been properly cared for. By avoiding exposure to degrading elements such as ultraviolet rays, heat, and oxygen, you’re ensuring that quality of the finished extraction product, regardless of extraction methodology. Base plant material should always be stored in an environment free from light or fluctuating temperatures, preferably in vacuum sealed (and nitrogen-filled) bags.
- Primary Extraction: The first step in the extraction process, primary extraction involves flushing cold butane through the solvent tank into the material column. This is where the hydrocarbon washes over the base plant matter – dissolving the terpenes and cannabinoids into the solvent. Once the plant material has been washed, the solution can be directly captured, or it can be processed in any number of ways.
- Refinement: At this point in the process, a choice of further refinement depends entirely on the desired end product. This could mean using something like in-line de-waxing, where the initial extraction is passed through stainless steel beads or another filtering medium, in order to hold back undesired materials. Or using another popular refinement technique used in tandem with hydrocarbon extraction, winterization uses a solvent such as ethanol at a high ratio to the base solvent. It is mixed with the extracted solution, and chilled to separate each element. This chilled solution then passes through a series of fine filters to separate out the waxes and lipids from the concentrated solution.
- Concentrate Collection: After refinement, the concentrate solution passes through to the collection pot, and any residual butane is passively removed. This purge moves the isolated butane back into the solvent tank, thus created a “closed-loop” system. This process repeats until the majority of the butane is removed from the solution –then the extraction collects the concentrate for further separation.
- Final Purging: There are multiple techniques for purging final solvent levels from the extraction solution. The desired end product will usually dictate which method is chosen – for example, when making shatter, the collected concentrate is spread thinly to expose as much surface area as possible, and then it is placed in a vacuum oven over a lengthy period of time (36-48 hours). But, when making something like wax, the initial concentrate is whipped over time to excise any remaining butane.
Main Techniques for Further Refinement of Hydrocarbon Extraction
After the hydrocarbon solvent has effectively isolated the desired plant material compounds, there are a number of compatible refinement techniques. Each of these methods results in a particular style of product, whether it’s shatter, live resin, CBD distillate, etc.
- Centrifugal terpene removal: The process of separating terpenes from a primary extract using a centrifuge device.
- Winterization: The process of removing plant lipids from a primary hydrocarbon extract via a secondary solvent, freezing, and filtration.
- Decolorization/Carbon Scrubbing: The process of removing the dark color and undesirable components of a primary extract via various filtration media.
- Dewax: The process of reducing and removing plant lipids via low-temperature single solvent isolation and filtration.
- Vacuum Purge: The process of removing residual solvents via a low-pressure low heat oven cycling.
- Decarboxylation: The process of removing the carbolic acid group from primary cannabinoids via heat.
- Co-solvent separation: The process of isolating one or more cannabinoids via matching various solvents to cannabinoid polarity.
- Co-solvent crystallization: The process of isolating cannabinoids via crystallization by matching various solvents to cannabinoid polarity.