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Challenges with Process Scale Up in Cannabis/Hemp Extraction

By Darwin Millard
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What makes scaling up your process so difficult?

There are many factors that can lead to the challenges people face when scaling up their processes. These challenges are not unique to the cannabis/hemp industry, but they are exacerbated by the consequences generated from decades of Reefer Madness. In my time operating in the cannabis/hemp space, 15+ years, I have seen established equipment vendors and sellers of laboratory supplies, like Sigma-Aldrich (now Millipore-Sigma), Fisher-Scientific, Cerilliant, Agilent, and others, go from reporting individuals inquiring about certified reference materials to setting up entire divisions of their companies to service the needs of the industry. Progress. But we are still a fledgling marketplace facing many challenges. Let’s look at a few specific to process scale up.

Darwin Millard will deliver a presentation on this topic during the Cannabis Extraction Virtual Conference on June 29. Click here to learn more.Equipment Availability: Lack of available equipment at larger and larger process scales can severely impact project timelines. Making not only equipment acquisition difficult, but also limiting the number of reputable equipment manufacturers you can work with.

Non-Linear Expansion: NEVER assume your process scales linearly. Perhaps one of the most avoidable mistakes during process scale up. You will quickly find that for many processes you cannot just put in a larger unit and expect a proportional increase in output. This is because as process equipment increases so to must utilities and other supporting infrastructure, but not only that, process vessel geometry, proportions, and design are contributing factors to process efficiency as your scale of operations increases.

Hazardous Material Quantities: Just as important to the process as the equipment are the solvents and reagents used. As your scale of operations increases so does your demand and production of hazardous materials; solvents including carbon dioxide (CO2), ethanol, and liquid petroleum gases (LPG) like Butane and Propane are obvious hazards, but so too are the refrigerants used in the chillers, fuels used to power generators, steam created to heat critical systems, and effluents and wastewater discharged from the process and supporting systems. Not every municipality wants thousands of gallons of flammable substances and hazardous waste being generated in their backyard…

Contractor/Vendor Misrepresentation: Finding out in the middle of you project that your contractor or equipment vendor has never set up a system at this scale before is never a good feeling. Unfortunately, contractor and vendor misrepresentation of qualifications is a common occurrence in the cannabis/hemp space.

If all this was not bad enough, all too often the consequences of improper planning and execution are not felt until your project is delayed or jeopardized due to misallocation of funds or undercapitalization. This is especially true when scaling up your production capacity. Now let’s look at some ways to avoid these mistakes.

The Rule of 10

Construction drawings for a piece of process equipment.

When scaling up your process, NEVER assume that a simple linear expansion of your process train will be sufficient. It is often the case that process scale up is non-linear. Using the Rule of 10 is one way of scaling up your process through a stepwise iterative approach. The Rule of 10 is best explained through an example: Say you are performing a bench-top extraction of a few grams and want to scale that up to a few thousand kilograms. Before jumping all the way to your final process scale, start by taking a smaller jump and only increase your bench-top process by a factor of 10 at a time. So, if you were happy and confident with your results at the tens of grams scale, perform the same process at the hundreds of grams scale, then the thousands of grams scale, tens of kilograms scale, and so forth until you have validated your process at the scale of operations you want to achieve. By using the Rule of 10 you can be assured that your process will achieve the same yields/results at larger and larger scales of operation.

Scaling up your process through an iterative approach allows you to identify process issues that otherwise would not have been identified. These can include (but by no means should be considered an exhaustive list) improper heat transfer as process vessels increase in size, the inability to maintain process parameters due to inadequately sized utilities and/or supporting infrastructure, and lower yields than expected even though previous iterations were successful. However, this type of approach can be expensive, especially when considering custom process equipment, and not every processor in the cannabis/hemp space is going to be in the position to use tools like the Rule of 10 and instead must rely on claims made by the equipment vendor or manufacture when scaling up their process.

The Cannabis/Hemp Specific Process Equipment Trap

How many times have you heard this one before: “We have a piece of process equipment tailor-made to perform X,Y,Z task.”? If you have been around as long as I have in the cannabis/hemp space, probably quite a few times. A huge red flag when considering equipment for your expansion project!

Unless the equipment manufacturer is directly working with cannabis/hemp raw materials, or with partners who process these items, during product development, there is no way they could have verified the equipment will work for its purported use.

GMP compliant phytocannabinoid processing facility underconstruction.

A good example of this are ethanol evaporation systems. Most manufacturers of evaporators do not work with the volumes of ethanol they claim their systems can recover. So how did they come up with the evaporation rate? Short answer – Thermodynamics, Heat Transfer, and Fluid Mechanics. They modeled it. This much surface area, plus this much heat/energy, with this much pressure (or lack thereof), using this type of fluid, moving through this type of material, at this rate of speed, gets you a 1000-gal/hr evaporator or some other theoretical value. But what is the real rate once an ethanol and cannabis/hemp solution is running through the system?

For a straight ethanol system, the theoretical models and experimental models are pretty similar – namely because humans like alcohol – extensive real-world data for ethanol systems exist for reference in designing ethanol evaporators (more accurately described as distillation systems, i.e. stills). The same cannot be said for ethanol and cannabis/hemp extract systems. While it is true that many botanical and ethanol systems have been modeled, both theoretically and experimentally, due to prohibition, data for cannabis/hemp and ethanol systems are lacking and the data that do exist are primarily limited to bench-top and laboratory scale scenarios.

So, will that 1000-gal/hr evaporator hit 1000-gal/hr once it is running under load? That’s the real question and why utilizing equipment with established performance qualifications is critical to a successful process scale up when having to rely on the claims of a vendor or equipment manufacturer. Except this is yet another “catch 22”, since the installation, operational, and performance qualification process is an expensive endeavor only a few equipment manufacturers servicing the cannabis/hemp market have done. I am not saying there aren’t any reputable equipment vendors out there; there are, but always ask for data validating their claims and perform a vendor qualification before you drop seven figures on a piece of process equipment on the word of a salesperson.

Important Takeaways

Improper design and insufficient data regarding process efficiencies on larger and larger scales of manufacturing can lead to costly mistakes which can prevent projects from ever getting off the ground.

Each aspect of the manufacturing process must be considered individually when scaling your process train because each element will contribute to the system’s output, either in a limiting or expansive capacity.

I go further into this topic in my presentation: Challenges with Process Scale Up in the Cannabis/Hemp Industry, later this month during Cannabis Industry Journal’s Extraction Virtual Conference on June 29th, 2021. Here I will provide real-world examples of the consequences of improper process scale up and the significance of equipment specifications, certifications, and inspections, and the importance of vendor qualifications and the true cost of improper design specifications. I hope to see you all there.

Until then. Live long and process.

Cannabis Extracts for the Informed Consumer: Solvent or Solventless

By Nick J. Bucci
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Editor’s Note: Nick Bucci is a freelance cannabis writer. You can view his work here 


As cannabis markets continue to gain traction, inconsistent and largely unpredictable markets have left recreational consumers in an informational fog. Try as the industry may, or may not to inform consumers, the lack of knowledge was evident when an established Colorado hash company opened a second operation in California. Expecting high demand for their solventless concentrates, the demand for their solvent-based counterparts came as a surprise. Initially hoping to eliminate solvent extracts from their product line-up, the company was forced to devote about half their overall production to solvent extracts, until information spreads and attitudes start to change. Over the past year several companies have joined the solventless side of history, but consumer understanding remains largely stagnant. For those immediately overwhelmed by terminology, cannabis extracts, concentrates or hash are all interchangeable terms describing concentrated cannabis. Under these umbrella terms, two distinct categories emerge depending upon whether chemical solvents were or were not used to extract the hash. Hence: solvent or solventless. A brief overview of cannabis concentrates will help consumers to understand the evolution away from solvent extractions and toward a superior solventless future.

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Science and economics merge when considering all the possible uses of concentrated compounds to final product formulations

Before regulated cannabis markets, cannabis extracts had long been in use. These old-world methods of cannabis extraction use very basic solventless techniques to create more potent, concentrated forms of cannabis. Dry sifting is easily the oldest form of cannabis extraction and a prime example of one solventless technique. Something as simple as shaking dried cannabis over metal screens and collecting the residue underneath creates a solventless product called keif. Dark brown bubble-hash, made popular decades ago, is another ancient technique using only ice and water to perform extractions without chemical solvents. After decades of stagnant and limited old-world methods, changes in legislation allowed cannabis sciences to flourish. These old-world hash methods were quickly forgotten, replaced by the astonishing progress of modern solvent extractions.

Tetrahydrocannabinol (THC), just one of hundreds of cannabinoids found in cannabis.

The emergence of solvent extracts revolutionized cannabis around 2011, creating new categories of cannabis products that exploded onto the scene. Not only did solvent extracts produce the most potent and cleanest forms of hash ever seen at this point, it also created new possibilities for hash-oil vape cartridges and cannabis extract infused edibles. These solvent extracts use butane, propane, or other hydrocarbon solvents to extract, or “blast” cannabinoids from the plant. By running solvents through cannabis and then purging or removing leftover, residual solvents, a super-potent, premium hash product is achieved. Regulated markets require testing to ensure only a safe level, if any, of the solvent used in the extraction process remains in the final product. This technology ushered in the first wave of concentrates to medical and recreational markets under the descriptive titles of wax, shatter and crumble. While these effective and affordable products can still be found today, far superior products have largely replaced wax and shatter. Distillation techniques can further purify and isolate THC-a, while removing harmful residual solvents. For a time, Solvent-free was used to describe this ultra-purified distillate, but the needless term has fallen out of use. Solvent-free is still a solvent extraction using chemical solvents, don’t be fooled. Distillation and CO2 extractions have fallen into general disfavor as they destroy the flavorful terpenes and valuable cannabinoids, that when present create an “entourage effect.” This “entourage effect” happens when the medicinal and recreational properties are most effective, pronounced, and impactful due to a full range of terpenes and cannabinoids being present in the final product. With companies manually reintroducing terpenes to their final extracts, it’s an attempt to restore what was lost during solvent extraction processes. Many brands claim to use cannabis derived or food-grade terpenes to infuse or reintroduce terpenes into their purified hash oils. While this adds flavor and taste, especially to distillate cartridges, it’s far from an ideal solution. Armed with this new information, the informed consumer looks for a full profile of terpenes and cannabinoids in their hash.

THC-A crumble, terpene-rich vape oil, THC sap (from left to right).

With terpene preservation a new priority, all aspects of hash making were reevaluated. By using fresh-frozen cannabis flower, solvent extractions quickly reached new heights. Using the same techniques as prior solvent extractions, the cannabis plant is frozen immediately upon harvesting, rather than trimming and drying the crop as usual. Freezing the plant preserves valuable terpenes helping to create a new category for hydrocarbon extracts under the general label of live resins. This live resin, containing vastly greater profiles of terpenes and cannabinoids than earlier waxes, shatters or crumbles is sold as live-resin sauce, sugar, badder, frosting, diamonds and more. Many versions of live resin re-use previous terms that describe consistencies. These live resin solvent extracts outperform the wax, crumble and shatters of old, and are priced accordingly. Some of the best solvent extracts available today use butane to extract hash oil, which forms THC-a crystals and diamonds seen in live resin sauces. Having learned the value of terpenes and cannabinoids, early efforts to purify THC were clearly misled. The industry defining use of fresh-frozen cannabis flowers greatly improved the quality of all extracts having realized the psychoactive effects are largely dependent on the various profiles of cannabinoids and terpenes. Pure THC-a crystals and isolates are easily achieved with solvent extractions but, produce inferior effects both medicinally and recreationally. Discovering the “entourage effect” as described earlier, these elements of cannabis allowed old-world solventless techniques to be re-inspired and reinvigorated with the benefit of healthy genetics and a hearty understanding of past mistakes.

Having gone full circle, solventless techniques are again at the forefront of the cannabis industry, having attained near perfection for our current understanding of cannabis anatomy.

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The increasingly finer mesh works to separate and extract microscopic trichomes

Using the lessons and tendencies of prior extractions, the solventless method, in all its final forms, begin with the same initial process to make ice-water hash oil. Often referred to as solventless hash oil (SHO), fresh-frozen flowers are submerged in ice and water, soaked and agitated before the water is filtered through mesh screens. As these mesh screens are measured by microns, the increasingly finer mesh works to separate and extract microscopic trichomes that break free from the cannabis plant. The 120- and 90-micron mesh screens usually collect pristine trichome heads. After scraping the remaining material from the screens, its sieved onto trays where the hash can dry using modern techniques of sublimation. The results are beyond phenomenal and are sure to shock even life-long cannabis consumers. This technique isolates only the most potent and psychoactive parts of the plant, to produce white to clear solventless ice water hash. When done with precision 6-star ice water hash is formed. The hash can be sold and consumed as is or undergo additional solventless techniques to produce hash-rosin. Not to be confused with live-resins, rosin uses pressure and slight heat to squeeze ice-water hash, into hash-rosin. Some companies have elected to whip their rosins into a solventless badder or allow their hash rosins to undergo a cold cure process that creates textures and varieties like hash rosin sauce. Regardless of the final solventless product, they all begin as ice water extractions. These simple, natural methods of extraction are quickly being adopted by companies known for live resin. As solventless extracts are safer, cleaner and superior in quality to solvent chemical extractions, the race is on as the industry shifts toward a solventless future.

While I’d be happy to never see another solvent extract again, without the miraculous breakthroughs and advances in all aspects of cannabis manufacturing and production we may have not yet arrived where we are today. When using solvents to extract, the trichomes, which contain the full spectrum of terpenes and cannabinoids, are dissolved by the solvent, which is then evaporated off, leaving behind dissolved trichomes. In solventless hash, these trichomes remain whole and are never dissolved or broken down. Instead they are broken free by agitation in ice and water, separating the trichome heads from their less-active stems. These valuable trichomes heads contain everything pertinent and are never destroyed, dissolved or melted like solvent-extractions are forced to do. The benefit of keeping the heads of these trichomes whole results in a far superior product expressing the full profile of terpenes and cannabinoids the way mother nature intended. This natural profile of trichomes lends itself directly to the entourage effect that solvent extracts were found to be missing.

Extraction techniques are not equal and depend upon whether quality or mass production is the aim. Solvent extracts have quickly begun to represent the old-guard of mass-produced cannabis concentrates, with the solventless new-guard focusing on quality, small batch, hash-rosin excellence.