Fine Particle Extraction Tips

Hello all,

I looked to see if there were posts already answering this, and didnt quite see anything that was exactly the same as our problem, please direct me to a post if I missed it though.

We recently came into a hemp contract that has a major particle size issue. The cultivator ground their material to a fairly small particle size prior to contacting me, not kief dust level but very fine.

I have worked with fines before, and have usually been able to deal with them by mixing them in with larger grains, however on this contract the whole batch was ground to this size and I don’t have any THC free material of larger size on hand at the moment.

We were going to use a packed column for the job as it is the only extraction rig we have in the area of the contract, we also only have it set up for hydrocarbon extraction. EtOH would require a new pump and/or setting up a soak/centrifugal rig.

Does anyone have any tips on how to deal with material of this particulate size?


how much of it do you have?
how much does your column hold?
where are your PRV’s set?

are you set up for a nitrogen assist?

I’ve heard of folks using pro-pak to keep their dewaxing filters from clogging, and some sort of 3D filter aid certainly seems like it might be in order.

I assume telling them to take it elsewhere isn’t an option you want to exercise. Are you planning to add a surcharge for the extra work they’ve made for you?

At that grind it will load into an unmodified beer keg easily, so there may be an ethanol route if you’re up for it.


I was looking to ditch my filter plates and screen gaskets to save on time and cost so I switched to using bentonite as a 3d filter aid and it has caused zero flow restrictions. I also clogged
My ports with copper mesh to prevent bentonite from passing through. You could load filterplates with bentonite if you have them. Based on your particle size im sure @cyclopath 's meantion of pressure relief valves and some sort of pressure assist (nitrogen hot butane, propane gas) would help in case flow stops


We currently have 10lbs out of 110lbs that we’re extracting before making a small bid on the rest.

The extractor in that area is only a small 2lb column + dewaxing column.

PRV on that one I think is 350psi not too high.

We are not currently set up for nitrogen.

The processing site near there is in a very rural area and is the furthest one from our main office (about 4.5 hour drive over 1 state line) At the moment it was only set up for basic extractions of small quantities. I could buy/build/modify some equipment and bring it with me, however Im not really trying to make an investment out of this unless its a modification or purchase that will assist me again down the road.

I preferably use cryo EtOH on hemp, so I’m not opposed to EtOH routes at all, but that would require a mod or purchase.

I don’t have the option of sending it somewhere else as it was part of a negotiation on another project that we do this extraction and refinement.

my PRV’s are set at 125PSI, so 350 sounds high to me :slight_smile:

knowing where your PRV’s are set is helpful in deciding how hard you can push. having them vent on you can be problematic if you don’t have them plumbed to a safe exhaust. plumbable PRV’s were one of the first mods I did on my PX1. (along with the replacing the 1/4 valves & lines)

@Apothecary36’s confirmation that DE is a go suggests that adding a nitrogen tank and regulator is probably your best bet. should run about $300 from memory.

yeah, you could warm your solvent to build pressure, and you wouldn’t have to burp the excess off. cheaper too. N2 is easier to control imo.

both of those assume you have a way of getting your solvent/recovery tank below 0oC. colder would be better for either route.

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@cyclopath For plumbing off a PRV are you using a compression fitting to a standard refrigerant line? Ive done vent lines in a similar way using needle valves.


then 1/4" JIC to a “standard” hvac hose

vs something like this which dumps in your space…


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If you want some icing on that cake you can add a larger dump tank under vaccum connected to that prv.if it pops the vapor goes to a safe place, heck you could even recover the vapor and reuse it!

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Yep. On the list.

We had / have a similar problem. We found no way forward until we had a nice lady sew up some 5 micron bags we bought from McMaster to put the hemp in. I’m not sure that helps since the geometry of your setup might not allow it. We spin dry the etoh out of the bag. All attempts to drain it through a filter of some kind at the bottom of the unit led to clogs and assorted nightmares. I would strongly advise against that.

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The other thing is that when it’s that fine, even at -35C w/ ETOH our extract is DARK. granted, our material is also old, but still, DARK. Doesn’t seem to be from chlorophyll either. Charcoal did nothing to lighten it. :confused:

I don’t think its chlorophyll, especially if you’re doing your extraction at low temperatures. I’ve definitely witnessed the darker “tea” and resulting crude from extracting older (dried and brown) biomass as compared with newer, greener biomass. I know this has been talked about at length on the ICMAG concentrated forum and from what I gathered is the same whether you’re extracting with butane, propane or ethanol.

With that said I don’t have enough of a chemistry background to say what the hell it is that is causing extracts to be so dark but at least you can sleep easier knowing that its effecting other extractors too

Sleep is for the weak, that’s why I need 14 hours every night, but i’m averaging about 6 during the week so I have an inadvertent unintentional manliness to me.


Well, there’s always supercritical CO2…

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