March 24, 2021

A previous issue of this newsletter described a turn-key hemp oil production plant which was designed and built by our affiliate, Plant Works Group, for a customer in the southeast. Those are facilities which cost in the seven figures.

Many operations in the industry start on a smaller scale. For them it works out most economically if they follow Do-It-Yourself steps.

CBD EXTRACTION
Right now EtOH extraction with a screw press is the cheapest and easiest way they can make a product. Screw press extraction gives approximately 95% efficiency of CBD oil removal from the hemp biomass.

An important benefit of using a screw press is that it maximizes alcohol recovery. Our model CP-4 screw press has proven to be an excellent screw press for newcomers to cut their teeth with. Washing with a 3:1 ratio, 85% ethanol recovery is achieved.

Downstream processing can get quite complicated. Or, it can be done in a fairly rudimentary way, inexpensively, as an introduction to refinement. The next steps are:

CRUDE PRODUCTION
Step 1:
Alcohol coming through the 150 micron wedgewire screen of the screw press is pumped to filtration equipment. Bag filtration works well. Stepped bags, starting with 100 micron, 60 micron and then 10 micron fabric, are recommended. A polishing filter with 2 micron medium is used for the final step.

Pressure vessels are ideal, although we see plenty of people who just allow gravity to do its work.

Step 2:
Activated carbon filtration is needed to take out Chlorophyll.

Step 3:
Winterization (deep chilling) is used to remove lipids, fat and waxes. This is a time and temperature process. Some of our customers get away with dry ice, if they can get it cheaply or produce it themselves. Otherwise they will need either a large freezer, capable of -20C to -60C (or even lower), or a jacketed tank with an associated chiller.

Plant Works Group recently bought a two stage (compressor) chiller on Ebay. It is a -80C chiller, and it cost us around $20,000. This, hooked up to a jacketed tank, would do the job. With the right temperature and time, the waxes will precipitate, allowing for removal by filtration. You have to take out the waxes and lipids or the finished product will not be acceptable.

Step 4:
Ethanol Recovery: An inexpensive approach is a large 50 liter rotovap. These cost around $10,000, as a guess. A less expensive chiller would be used for condensing EtOH. The more expensive approach is a small scale kettle or falling film evaporator ($100k+).

Step 5:
Decarboxylation or Decarbing: The crude must be heated to 70+C for a period of time. This is done to convert CBO-A to CBD. The CO2 is exhausted. It is important to evaporate the alcohol under a vacuum, to prevent oxidizing some oils.

Once the solvent is removed, the temperature is held, under vacuum, long enough to get an active CBD product.

At this point a winterized, decarboxylated crude oil with all residual EtOH removed has been produced. The industry refers this as CBD crude oil. It is a very thick black fluid at room temperature. At temperatures over 120F this turns to a water-like consistency.

DISTILLATE PRODUCTION
Distillate is the honey gold colored oil, near enough to be a pure CBD product.

Step 6:
For around $5K a single mantle glass distillation set-up will produce around 1 liter of 80% – 85% CBD distillate per day. This is done at high temperature and a deep vacuum, 175C and 50 mTorr. Under these conditions, residual solvent, humidity, and terpenes are boiled off and stored separately from the distillate.

In a nutshell, newcomers need to get their heads around the above set-up for lab scale, minimum expenditure, processing. If they don’t have $25,000 – $50,000, in addition to the screw press, to spend on some essential equipment, then they will be hard pressed to make a finished product through this solvent extraction process.

The above is a good first phase in the learning process. Once the newcomers master this and develop some SOPs that work for them, they will be able to embark on scaling up. A recommended option is to engage an engineering firm like Plant Works Group to expedite the path to the market.

Practical experience in this industry is vastly underrated by new money; they always think that they will be fine. The bottlenecks and hurdles are fairly cumbersome.

ISSUE #332