Our lab is looking at pelletizing our biomass for both CO2 and cold/warm ethanol extractions. Some consultants we’ve spoken to think it has potential, others think it won’t be cost efficient due to potentially lower % yield on our biomass (due to channeling/reduced surface area). Our hope is that the higher yield per run would be cost efficient even if the yield from the biomass was indeed slightly lower.
My question is whether anyone has tried this, and if so can you give us information on whether this is a worthwhile endeavour, or whether we should stick to loose or armstrong-packed biomass.
Or if anyone wants to speculate I’m open to that as well!
I hear that if you squeeze hard enough you can get the cannabinoids out without the solvent
I’m having a hard time seeing how pellets would pack well enough to avoid major channelling.
I’d suggest kiefing instead. although the SFE manufacturers I’ve discussed this with were dubious, and you might want to talk to @EndlessOps about their experience extracting with alcohol before committing to anything large scale.
Both our CO2 and ethanol extraction machines have means of agitation, which we were hoping would mitigate channeling. Our CO2 machine rotates the biomass vessel and alternates direction of flow, and our ethanol extractor uses rigorous rotational agitation as well.
With bucket tek and our old CO2 machines it would not be viable, but it would be nice to capitalize on all this added solvent penetrating power we are adding.
I doubt it would cause a negative effect, having pellets wouldn’t create more channeling problems than packing ground trim very tight. In the end you’ll be running way more material that will most likely make up for the very minimal yield loss.
If only consultants had proof of the things they’re preaching, not just “think” it would or wouldn’t work…
guessing that means you’re running an Azoth CO2 machine? have you asked @Jonaaronbray re: pelletizing the biomass?
I don’t see agitation solving the channelling issue in this case, it may move the easy path (around the pellets rather than through), but it won’t force the solvent to take the hard path (through the pellets). in the case of your ethanol extractor, which I assume stirs rather than rotating the vessel (unless you’ve got a CUP), one might even expect agitation to depelletize the biomass and turn what would ideally be a slurry into an essentially solid unstirrable mess.
given you’ve already got the expensive part (assuming an Azoth and ???), grabbing a cheap pellet mill and trying it seems the most direct route to answering your question.
I’m not familiar enough with the Azoth extraction chamber to know if loading single compressed pucks would be a viable alternative. At least conceptually, that strategy removes the most of the “paths of least resistance” which I think will trip you up loading compressed pellets.
on the plus side, if you buy the pellet mill, and it doesn’t give you the increased extraction efficiency you’re after, you can always use it to pelletize the spent biomass. which might give you another product you can sell, or be used to power a steam generator to offset some of your energy costs.
I see trim, being randomly sized, packing together better than the small cylinders most pelletizing mills generate. even stuffing those cylinders in as tightly as you can manage would seem to leave more open space (channels) than monolithically packed trim.
we’re both speculating…and I certainly think it’s worth trying. I just can’t see how to pack cylinders without leaving gaps.
We will indeed be running the Azoth and CUP machines.
If @Jonaaronbray had any insights I would love to hear them.
Our hope is that the solvent will expand and loosen the pellets and allow solvent to penetrate into it for effiicent extraction.
I’m also looking into how breweries do this, as some breweries use pelletized hops. If that is a succesful endeavour then hopefully ethanol extraction of cannabis is a similar enough of a procedure.
You’re right though, a hands on experiment and cost efficiency analysis is the only way to find out for sure.
Hops are pelletized before they are extracted with super critical CO2. The denifsication of the powder reduces bulk density and allows you to pack more material into the extractor. It also allows you to grind the powder up more finely so you get higher yields without plugging the screens. Finally the pressures produced during the pelletization ruptures the gland at the end of the tri-comb so that the resins inside are available to the CO2 without having to dissolve the waxy cuticle. The pellets for extraction are different then the pellets for brewing in that they optimized to reduce interstitial volume and prevent channeling.
Have you ever brewed with peletized hops? They break down into mush in the boil kettle. I think your cannibinoids pellets would perform similarly with solvent and agitation. How are the pellets different?
A properly extracted pellet should fall apart with any mechanical action. I don’t like pellets personally because the oil tends to be darker than a non pellet extraction.
With a good mill you can fit as much in a extraction vessel as you could with pellets. A mill can also fill extraction bags automatically so this makes it possible to mill hours before the extraction to retain as much terpenes and acid forms as possible.
Could you recommend a good mill, especially for fresh sticky material? or particle size to end with? I’ve been looking at quite a few but have had concerns about the resins causing problems. Even a few good companies anyone could recommend looking into would be helpful. Thanks!
G Farma spoke at Emerald Conference in 2016 about how pelletization increased their loading and yield by 3x. If I remember correctly, the trick is to set the pelletizer for a slightly lower compacting strength as over crushing the pellets causes problems.
Colour of oil aside (say for distillate/phoenix tears/oil that will be decouloured anyway) do you find your yields were appreciably higher while running pellets?
In regards to your second paragraph, are you saying that the a mill could blow milled biomass into a bag with similar density as pellets, while being less susceptible to channeling effects?
I think this is part of the reason for the varying opinions on this, is a differing idea of what size/shape/density of pellet is being extracted. Some pictures of pelletized materials are incredibly densely packed and look as if they would be very resistant to solvent penetration and leave massive channels. Other pellets, however, are shaped to settle well with each other, and are packed enough to increase density while still being penetrable by solvents.
Glad to know we aren’t completely on the wrong track though
The 3x increase in loading capacity refers to a 3x compact rate. So if you have a pellet machine that compacts 6x the material into a pellet it would be too tight. I can’t remember the values they use to represent this, volume/weight would be my first guess. @Monera
Densification! I learned a new word, does that mean I can quit for the day?
Specially shaped pellets, and lower than wood pellet density certainly make the problem look different. changing the pellet shape was the first place I went after deciding that the cylinders that the pellet mills I’d seen produced didn’t look like they’d pack well. I can certainly wrap my head around there being shapes that pack better, I can’t immediately see what shape(s) might be optimal. Clearly the experiment has been done, and deemed successful if it’s being done commercially with Hops.
I’ve had personal experience with getting wood stove pellets wet when already packed tightly in a container. Which is why I was concerned with locking an agitator when ethanol was added. 3x compression ratio rather than 6x compression ratio would seem to make a difference there as well.
The Azoth process is unique in more ways than agitation. The volumes of Co2 used and metered into the extraction vessel in specific volumes provides options for how the extraction is performed, and can be tailored through user adjustable settings for pellets.
Using pellets in traditional continuous flow through a high pressure vessel into a lower pressure vessel will not work very well. Traditional SCFE uses this method and will work better with a completely uniform compression of the biomass, while being less efficient as biomass density decreases.
Happy to share info with anyone experimenting with Co2 extraction.
One thing I think people miss alot when talking about increasing the amount of biomass in an extraction vessel is the cycle time should increase as the available compounds do. The cycle time is based on the amount of available compounds that you are targeting. If you fit 50% more of the same biomass in an extractor it should have 50% more Co2 cycled through it.
Understanding this also explains why a Liquid Co2 extraction is faster than supercritical. The Liquid Co2 does not seek Fats, Waxes, Lipids, Water and plant pigments whereas SCFE does. This increases the targeted compounds by 100-200%. When the Co2 is pulling up to 3x the compounds it takes 3x the Co2 to pass through the material, and 3x the time. This is the minimum amount, as the Co2 doesn’t return to the extraction vessel in pure form. SCFE as the systems available today perform it, leaves VOCs entrained in the gas phase to the condenser for liquid pumps and to the pump on gas pumps. Co2 entering the extraction vessel that is already partially loaded with compounds can not extract as much per pass as pure Co2. These VOC also act as a co-solvent and effect the process.
Imagine that Co2 is a subway train. The subway station needs to move 100 people and each train holds 50 people. The train that comes to the station empty each time will only take two trips. A train arriving half full to the station each time will take 4 trips. Twice as long to move the same mass. Using the same analogy, what if there was 100 targeted people, and another 200 non targeted people to move (ie. wax, water and plant pigments). The train that only allows the targeted people, is far more efficient. Still 2 trips for the “empty / targeted” train, and 8-12 trips for the “loaded / non-targeted” train.
The Separator on SCFE systems is to separate the extracted compounds from the Co2, so the Co2 can be reintroduced to the start of the process. Ask yourself this. If separator 1 worked, why would separator 2 have anything in it? If separator 1 didn’t completely work did #2 or #3.
You can say Co2 does or doesn’t work. However you should really talk about individual Co2 processes and their effectiveness. This has been a mute point as most the systems on the market are a copy of the same copy.
