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Bulk Subzero Ethanol Extraction

Gray Wolf

Gray Wolf

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Old Gold said:
I somehow got away with 1/4 HP, and it offers 35 ft of head while operating at 14.2 PSI. We are able to push it through two 50 ft cooling coils and two jacketed 12"x30" cylinders simultaneously (inlet at the bottom of jackets). For any seriously large application, surely a 1/2 HP or greater would be minimum.
Click to expand...

Thanks, I'll take a look at the smaller pumps.

A foot of head is 0.4332 psi (0.0361lbs/in2 X 12") and for the pump to reach that pressure, requires that much back pressure.

Back pressure is a function of flow, so the pressure required will depend on how much liquid is being pumped through what resistance. As the pump size and flow goes up, so does the pressure and horsepower requirements.
 
A

Alister.Frazzle

New member
As an extractor hoping to change from room-temp to subzero extractions I find this post to be quite useful in my creative process! With dry ice in the solvent tank what extraction temperature do you think would be realistic? And how long would you expect to recirculate alcohol before beginning to pick up polar compounds? Perhaps a cryogenic centrifuge or a filter press of sorts could be implemented in the extraction vessel for maximum solvent recovery.
 
Gray Wolf

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Alister.Frazzle said:
As an extractor hoping to change from room-temp to subzero extractions I find this post to be quite useful in my creative process! With dry ice in the solvent tank what extraction temperature do you think would be realistic? And how long would you expect to recirculate alcohol before beginning to pick up polar compounds? Perhaps a cryogenic centrifuge or a filter press of sorts could be implemented in the extraction vessel for maximum solvent recovery.
Click to expand...

Between -50 & -70C.

5 minutes or so.

A centrifuge would probably work better than pressing it, but the recovered alcohol would be of different quality and should ostensibly be processed separately.

You could also heat the material while pulling a vacuum, and pull off the alcohol as a clean vapor, followed by condensing it back to a liquid.
 
mobin

mobin

Member
Gray Wolf said:
but the recovered alcohol would be of different quality and should ostensibly be processed separately.

You could also heat the material while pulling a vacuum, and pull off the alcohol as a clean vapor, followed by condensing it back to a liquid.
Click to expand...

even under vac i end up with some azeotroping stank on initially recovered alcos.

50-80mmHg/torr at around 55*c, zero visible reflux/vapor trail, and only seeing condensation once in the trap.
 
SkyHighLer

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Gray Wolf said:
Between -50 & -70C.

5 minutes or so.

A centrifuge would probably work better than pressing it, but the recovered alcohol would be of different quality and should ostensibly be processed separately.

You could also heat the material while pulling a vacuum, and pull off the alcohol as a clean vapor, followed by condensing it back to a liquid.
Click to expand...

On the centrifuge idea, how about first spinning up the dry material at high speed to pack it, and then hitting it with with sprays of cold solvent, gradually ramping up the rpm's, and taking factions as you go?

As to vacuuming off solvent, once most of the solvent's gone, transferring heat evenly through the material might be a problem.
 
G.O. Joe

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SkyHighLer said:
As to vacuuming off solvent, once most of the solvent's gone, transferring heat evenly through the material might be a problem.
Click to expand...

Heat the bottom, make the vessel short and fat chemical industry style instead of tall and narrow supersized BHO style. Instead of pressing or centrifuging, then distilling to recover gunkage and ethanol, why not heat the cake left after after vacuum or pressure filtration, condense the solvent, and leave the crap in the cake and the money spent for the sludge dryer and filter press or centrifuge somewhere else? There are already shiny and fully compliant devices along these lines as fancy as you could want. Such extraction can be mostly done in the insulated and cooled slurry mixer for the pressurized filter with heater, cake stirrer and washer, with washing of the cake until satisfied.
 
Gray Wolf

Gray Wolf

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G.O. Joe said:
Heat the bottom, make the vessel short and fat chemical industry style instead of tall and narrow supersized BHO style. Instead of pressing or centrifuging, then distilling to recover gunkage and ethanol, why not heat the cake left after after vacuum or pressure filtration, condense the solvent, and leave the crap in the cake and the money spent for the sludge dryer and filter press or centrifuge somewhere else? There are already shiny and fully compliant devices along these lines as fancy as you could want. Such extraction can be mostly done in the insulated and cooled slurry mixer for the pressurized filter with heater, cake stirrer and washer, with washing of the cake until satisfied.
Click to expand...

No reason to reinvent the widget!
 
G.O. Joe

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What if stirring a slurry, filtering, and washing gives better more even extraction faster than a column, for the cost of a second tank and mixer that would be nice to have.

Unless it has been/is being arranged for OR law to read BHO technique is mandatory? Stirrer blades and jet pumps are safety hazards, improper engineering, and certainly not best practices eh?

If a legit chemical company was extracting pot with SDA, they probably wouldn't try very hard to recover it - the nutsche cake would just be blown through until dry enough for the landfill, as EPA smiles and waves.
 
C

c03rcion

New member
I have been working on a cold ethanol extraction method but just can't seem to get my yields higher than 5%. I am working with bud that was freeze dried after harvest and stored in a freezer. The ethanol is 200 proof and is kept, along with everything else, in a -86 C freezer. I have even tried doing a 30 minute wash, and while the color and clarity are still great, the yields don't get better.

Any suggestions? Is this too cold for an effective wash?
 
WaterFarmFan

WaterFarmFan

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c03rcion said:
I have been working on a cold ethanol extraction method but just can't seem to get my yields higher than 5%. I am working with bud that was freeze dried after harvest and stored in a freezer. The ethanol is 200 proof and is kept, along with everything else, in a -86 C freezer. I have even tried doing a 30 minute wash, and while the color and clarity are still great, the yields don't get better.

Any suggestions? Is this too cold for an effective wash?
Click to expand...

5% is very low if you are processing flowers, but it depends on the quality of the starting material. I get over 25% return doing a single -50C pass with soak times of 20-30 minutes using very high grade flowers that have been cured and are ground to less than 500 micron.

How are you pre-processing the flowers? Were the buds dried first and then frozen or frozen fresh? If material is fresh frozen and you are not drying it, perhaps the very high water content and very low temps are locking out the alcohol from extracting the cannabinoids. If you are not processing the material into smaller pieces, then perhaps this effect is amplified even more.

As a test, you can thaw and dry a volume of material in oven to near complete dryness. There might be some decarbing in your sample, but it will give you a baseline.
 
WaterFarmFan

WaterFarmFan

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Also, if your material is fresh frozen, then your starting weight will be very different compared to the same exact material that has been dried. 1000 grams of fresh cut flowers might weigh only 100-150 grams when dried. You could again weigh a sample before and after oven drying to get a baseline, so that you can get an accurate yield percentage.
 
Gray Wolf

Gray Wolf

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c03rcion said:
I have been working on a cold ethanol extraction method but just can't seem to get my yields higher than 5%. I am working with bud that was freeze dried after harvest and stored in a freezer. The ethanol is 200 proof and is kept, along with everything else, in a -86 C freezer. I have even tried doing a 30 minute wash, and while the color and clarity are still great, the yields don't get better.

Any suggestions? Is this too cold for an effective wash?
Click to expand...

You need longer soaks at -86C and flow or agitation.

Check your spent material with a microscope to check progress.
 
C

c03rcion

New member
The bud was fresh harvested and kept in the freezer, where after sometime it was transferred to a freeze drier and moisture removed. Bud was then kept in freezer once freeze dried. Material is pretty descent, good bit of trichomes and smells very nice.
 
WaterFarmFan

WaterFarmFan

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Have you thawed the material and then refrozen? It will have no ill effect on the ability to extract. Have you tried braking the material into smaller pieces? If material is frozen in your deep freeze, it would be quite easy to smash with a pestle to get a finer material. You will need a better way to filter the fine material as with a vacuum assisted buchner and whatman #1 filters. It would help you test yields if you allow the etoh to warm a bit from -86C to -50C while you buchner filter, which takes longer (10-20 minutes) with 1 micron filter and finer ground flower material. I was concerned that I was not picking all the terpenes at -50C, so I allow the material to drift to -30C at the end of filtering. You might get a tiny bit more chlorophyll pickup, but the green color always disappears within a hour, and less if I start vacuum distillation immediately. I always end up with a honey amber color shatter.
 
C

c03rcion

New member
WaterFarmFan said:
Have you thawed the material and then refrozen? It will have no ill effect on the ability to extract. Have you tried braking the material into smaller pieces? If material is frozen in your deep freeze, it would be quite easy to smash with a pestle to get a finer material. You will need a better way to filter the fine material as with a vacuum assisted buchner and whatman #1 filters. It would help you test yields if you allow the etoh to warm a bit from -86C to -50C while you buchner filter, which takes longer (10-20 minutes) with 1 micron filter and finer ground flower material. I was concerned that I was not picking all the terpenes at -50C, so I allow the material to drift to -30C at the end of filtering. You might get a tiny bit more chlorophyll pickup, but the green color always disappears within a hour, and less if I start vacuum distillation immediately. I always end up with a honey amber color shatter.
Click to expand...

The bud was harvested from the field and placed in a walk in freezer. The frozen bud was then broken up and and placed in a freeze drier. Then returned to the walkin. Bud is very dry and will crumble easily.

Have done a few runs with it now and the end product always looks great, amber shatter. Terpenes are present, smells and tastes are great. The yield has just been a consistent problem.

I just tried doing a wash on 1.6 gram of bud i broke into dime sized pieces or smaller. Left it in the -86 freezer for 1.5 hours, swirling the little container every 15 minutes. After filtering the solution, laid the bud pieces on paper towel to dry and checked them under the microscope. To my surprise there were still trichomes!!! Maybe I should agitate the wash more?
 
WaterFarmFan

WaterFarmFan

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It definitely sounds dry then if it crumbles. You really just might be going too cold. Start it out of -86C and then place outside the freezer and let the temps rise some to around -50C using a thermocouple to measure.

I have done quite a few ethanol extractions using nothing but trichomes collected from dry ice hash. Most of the trichome matter remains after the ethanol wash, as ethanol only interacts with some of the organic matter that composes the trichome head and stalks.
 
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