Description of the invention

Background of the invention

Industrial hemp is a versatile plant cultivated worldwide for its many applications in the food, pharmaceutical, cosmetic, agricultural, construction industry, phytoremediation and other industrial branches [1], Most of the industrial applications of hemp are related to the fibers and seeds, which represent a large proportion of the whole plant, while the inflorescences are mainly used for the pharmaceutical industry and the roots for phytoremediation.

The unique feature of the plant is that by a suitable pretreatment and design of the processing method, practically no waste material is remaining, as each part of hemp is used due to its own potential to be formulated into a specific product. Therefore, by careful design of the procedure and particularly specific steps, the preliminary treatment of the material (e.g. transplanting process) that separates the parts of the plant is very important. This step allows the material to be grinded to access its specific active ingredients, resulting in extracts with higher proportion of the selected compounds.

The fundament of the invention is a process for pre-treatment of the industrial hemp crop (transplantation process) for separating plant parts according to the content of biological components. Such a precise separation of dried material has not yet been presented in the literature. Through separation, we achieve greater selectivity of the required components already in the raw mass, which enables significantly higher yields of the target components during the isolation steps.

Due to the diverse composition of the plant, the optimal use of all plant parts represents a major challenge to which this invention relates. In practice, the hemp crop is mostly used as a single source. Seeds for oil and fuel, stems as a source of fiber, flowers as a source of pharmacological components. In some approaches, the remaining material is valorized by reprocessing or discarded. The special advantage of the present invention represents a screening method that completely eliminates by-products and waste, as the plant parts are accurately separated according to the various desired products already in the material prepreparation step itself.

The input material (harvested dried industrial hemp - seeds, flowers, leaves, stems) passes through 4 separators (crusher, rotating seeding drum, cyclone and inclined screen) between which closed conveyor belts to avoid impurities should be placed. After each separator, collection container is retained to collect the selected fraction. The process is designed to separate the material into 6 final fractions, with a more homogeneous structure and a higher content of definite components present in a specific part of the plant.

According to the international patent classification, the process is classified in categories B07B - separation of solids from solids by sieving; to category B02C23/10 - separation or sorting of material associated with crushing or disintegration with a separator installed in the discharge path of the area of crushing or disintegration and to category A61K36/185 - medicinal preparations of unspecified composition containing substances from algae, lichens, fungi or plants or their derivatives, e.g. traditional herbal medicines - subcategory of Magnoliopsida (dicotyledons).

State of the art

Industrial hemp has a high yield per hectare (up to 25 tons of dry material per hectare) [2], as it is one of the most efficient plants in terms of the ability to grow (5-6 m per year), use of solar energy and regulation of CO2 [3], Stems (44% of the entire plant) and fibers (24%) are used in the construction and transport industry due to their strong structure, oil and biofuel are produced from the seeds (11%), and the inflorescences and tops are a source of cannabinoids, terpenes and other pharmacological components, which are found in plant trichomes [4],

Nowadays, industrial hemp is mainly grown for both fiber and seed production. Fiber is still the main product obtained from hemp straw, while the main product derived from seeds is oil [3], Different varieties of hemp produce different amounts and quality of fiber, i.e. long pith or short pith, as well as seed size and oil composition [5], Mainly two groups of hemp varieties are cultivated. Varieties grown mainly for the stems, i.e. fibers used for building materials, clothing or animal-related purposes and varieties grown for oil-producing seeds, e.g. for cultivation and food [6], Hemp can also be grown as a dual-purpose plant, meaning that both the fiber and the seeds can be processed. This practice affects the quality and quantity of fibres, e.g. a specific fiber crop yields the best quality powdered fibers for textiles and composites [7], The yield and quality of hemp biomass largely depends on the genetic background of the plant. It is also strongly influenced by environmental factors such as temperature and light [3], Industrial hemp differs from medical hemp in the content of psychoactive tetrahydrocannabinol, which must be lower than 0.2 wt. %. Nevertheless, industrial hemp is also cultivated for therapeutic purposes, in this case extracts with high contents of cannabidiol and other non-psychoactive cannabinoids are produced [3],

Depending on the purpose of use, the time of harvesting of the grown plant is already determined. Inflorescences are harvested between August and September [8], Plants grown for medicinal purposes and isolation of pharmacological components are usually harvested by hand. Individual inflorescences can be collected, from the top of the plant downwards, while the lower ones ripen continuously in a total interval of ten days [9], However, the whole plant can be harvested, the stems are separated, and the inflorescences are dried in order to obtain the highest quality material [6], The remaining leaves are manually removed from the inflorescences, subsequently the content of cannabinoids, the presence of heavy metals or pesticide residues are evaluated [6,9], Up to 90 wt. of leaves can be removed during mechanical processing of freshly harvested inflorescences, the remaining 10 wt. % is usually removed manually [9], In the conventional process of growing industrial hemp, the stalks and seeds are harvested simultaneously with a harvester, and the remaining stalks are compressed into bales. When the seeds ripen, they become lignified, which means that the equipment needs to be cleaned several times already during the harvest, and it is often damaged. For this reason, plants grown for fiber are harvested before the seeds mature [10], Immediately after harvesting, the material must be processed in a way that protects it from impurities and pests, stored in a way that prevents damage, dried as soon as possible (most often hung in barns) to prevent chemical decomposition and protected from excessive light and moisture [9], More detailed description of cultivation, harvesting and processing of hemp can be found in the professional literature [9,11,12], Current systems for producing cannabinoids from industrial hemp involve labor-intensive manual harvesting, which increases labor and production costs. As a result, harvesting systems are changing dramatically. The labor-intensive model of manual harvesting is already being replaced by mechanization, which is more typical for grain and feed. In cereal systems, attachments/units are added to harvesters to collect seeds and tops, which can be valuable for extraction, otherwise the tops must be read manually or sifted with various devices [13], A number of techniques have been developed for the extraction of chemicals from the inflorescences of industrial hemp, which differ depending on the target chemical, such as mechanical extraction, Soxhlet method, hot water extraction (hydrolysis) [14], liquid-liquid extraction with dimethyl ether [15], supercritical CO2 extraction [16], enzyme-assisted extraction [17], microwave-assisted extraction [18] ], ultrasonic waves [19], etc. [20], Recent studies have shown the successful application of supercritical fluids and organic solvents for the extraction of cannabinoids, terpenes and fatty acids [20], Despite the effectiveness of organic solvents, supercritical CO2 leads in terms of economy, ecological aspect, and the larger ability to separate components on an industrial scale. The method allows up to 100 ut. % yield of cannabinoids based on input material [21],

Many methods of using industrial hemp are described in patent documents, especially cannabinoid extraction and concentration procedures (US20150203434A1 [22], US6403126B1 [23], US7700368B2 [24], US20170020944A1 [25], EP1326598B1 [26]). Also, techniques for separation of hemp parts are described (CN101181092B [27], EP3888451A [28], CN111837673A [29], US20170202896A1 [30], US10052636B2 [31]). The existing patent documents are related to the separation of seed cores and shells, plant resin from the rest of the material, processing of the stems for an optimal proportion of fibers and optimization of the entire process of growing and processing hemp with the goal of the highest possible content of pharmacological components. The patent documents also describe devices that separate plant material by particle size (US16814695 [32]), separate stems and leaves, and weigh and package the plant (US20180339298A1 [33]).

The patent document US20190201936A10 [34] describes the process and device that enables separation of the trichomes of medical cannabis from the flowers, but the possibility of exploitation of other parts of the plant is not discussed in the document. The patent document US20220105521A1 [35] describes the process of separating the plant into fractions according to its composition, but the process does not deal with the separation of seeds and the separation of trichomes.

Disadvantages of the existing solutions

When processing industrial hemp, the entire process is usually adapted - optimized - to the desired main product, which is usually only a certain part of the plant (fibers, seeds, inflorescences). The remaining parts of the plant are discarded in individual cases but can be used for by-products. However, the starting material for these is usually of lower quality than the material subjected for further processing to attain the main products. The present invention presents a solution that allows automated separation of the hemp plant and preparation of high-quality raw materials for optimal processing of the whole plant. Particular attention is given to the separation of the trichomes from the inflorescences, which have a high content of pharmacological components, so that a special fraction of plant trichomes rich in cannabinoids and a special fraction of trichomes rich in terpenes are presented. The aforementioned patent US20220105521A1 [35], which allows the processing of useful hemp, does not cover the extraction of CBD powder and the separation of seeds. Moreover, the process in the above cited document is much more time consuming compared to the process according to the present invention. Comparing the scheme of the process according to the invention with the scheme presented in the cited patent document, the process suggested as the invention achieves a more precise fractionation of the products with significantly fewer elements and steps. However, the patent document US20190201936A10 [34] from 2019, which focuses on the separation of the trichomes of medicinal cannabis, discrards the rest of the plant material. Compared to the suggested method according to the present invention, both cited solutions are also much longer and more complicated, with lower separation efficiency which yields final products of lower quality. This are the main disadvantages that which makes our solution much more advantageous and feasible compared to them.

The method according to the invention, focuses on the step of preliminary preparation of the useful hemp plant for optimal separation of plant trichomes and other plant parts according to the content of biological components. The approach gives two fractions suitable for the extraction of pharmacological active substances, taking into account that the leaves contain a relatively lower content of the desired components and the inflorescences are a very selective extraction material.

Detailed description of the invention

Hemp has great potential for sustainable planning of the entire production and processing steps. Since each part of the plant has the potential for becoming an individual product, the most important step in planning is the pre-treatment of the material, which separates the parts of the plant according to the future application. This enables the fragmentation of the material according to the content of pharmacologically useful, bioactive components, which leads to a higher selectivity of the obtained material/fractions. The components with the highest added value in industrial hemp are primarily cannabinoids. The innovative process for the preliminary preparation of the industrial hemp crop (seeding process) was designed with the aim of optimizing the isolated amounts of the mentioned components with regard to the parts that do not contain them and will be used for the production of fibers, oil, biofuels, etc. The existing solutions do not enable such efficient utilization of all parts of the plant as proposed approach.

Figure 1 represents a schematic of the process according to the invention.

The process according to the invention is carried out in an apparatus consisting of a crusher 1 with a screen, a rotating sieving drum 2, an inclined sieving screen 3, a cyclone separator 4, which are interconnected by closed conveyor belts 5, and five closed collecting containers Z1 to Z5. All the dried harvested material is processed, and six final fractions of the input plant material VM are obtained. The use of closed conveyor belts 5 and closed collection containers Z1 to Z5 limits the loss of material to less than 3 wt. % with respect to the input plant material VM, i.e., the whole dried plant, and prevents its contamination. The input plant material VM is industrial hemp of the species Canabis indica or Canabis sativa with tetrahydrocannabidiol content of less than 0.2% by weight in respect to the weight of the input plant material.

The whole dried plant, i.e., the input plant material VM, is partially crushed in the crusher 1 with a screen (10-30 mm screen), where the thick stems are separated from the rest of the plant material and collected in the first collection container Zl. The thick stems have a diameter between 10 mm and 30 mm and represent the first final fraction Ml of the VM plant material. The rest of the plant material is transported by the conveyor belt 5 to the rotating sieving drum 2, which contains screens with an opening diameter of 2-5 mm. In the rotating sieving drum 2, the seeds and smaller stems are separated from the rest of the material. The seeds and smaller stems pass through the closed conveyor belt 5 to the closed cyclone separator 4, where separation of the seeds, which represent the second final fraction M2 of the incoming plant material VM from smaller stems takes place. Those are collected in the second collection container Z2. The smaller stems, which represent the third final fraction M3 of the input plant material VM are collected in the third collection container Z3. Stems and seeds are separated according to their weight difference. Thus, in the upper part of the cyclone separator^ the stems are obtained, while the seeds are collected in the lower part. The expressions "secondary stems" and "stems" are used for stems that separate from the main stem of the plant and have a diameter of less than 10 mm. The material that does not fall through the rotating sieving drum 2 passes via the closed conveyor belt 5 to the inclined sieving screen 3, under which the fourth collecting container Z4 is separated into a first part Z41 and a second part Z42. The inclined sieving screen 3 contains openings with a diameter of 50 pm to 500 pm. Into the first part Z41 of the fourth collection container Z4, flower trichomes are sieved, which mainly represent cannabinoids (a fraction of the plant trichomes rich in cannabinoids), and which represent the fourth final fraction M4 of the plant input material VM. Flower trichomes representing mainly terpenes (the terpene-rich fraction of the plant trichomes) and representing the fifth final fraction M5 of the plant input material VM, are sieved into the second part Z42 of the fourth collection container Z4. The material remaining on the inclined sieving screen 3 represents the flowers and leaves containing small amounts of cannabinoids and is collected in the fifth collection container Z5 and represents the sixth final fraction M6 of the input plant material VM. The presented process separates the input dried material by plant parts, which allows optimal further processing and production of products.

The inclined sieving screen 3 has an inclination (with respect to the horizontal bottom surface) of three degrees to ten degrees, preferably five degrees. It is desirable that the material is moved across the inclined sieving screen 3 as slowly as possible so that the yield is as high as possible. If the amount of the material is low, a higher inclination of the sieving screen 3 is required to move the material along the sieving screen, while if the amount of the material is large, the inclination of the sieving screen 3 may be lower. The two fractions of plant trichomes are separated on the inclined sieving screen 3 according to their size and weight. Cannabinoid molecules are heavier, so the fraction of plant trichomes rich in cannabinoids falls through the openings on the inclined sieving screen 3 earlier, while terpene molecules are lighter, so the fraction of plant trichomes rich in terpenes falls through the openings on the inclined sieving screen 3 later. In this way, the flower trichomes, which mostly represent cannabinoids, are first sieved into the first part Z41 of the fourth collection container Z4, and in the second part Z42 of the fourth collection container Z4, flower trichomes representing mainly terpenes are sieved. The size of the openings on the sieve 3 is chosen depending on the desired purity of the M4 or M5 fraction. The choice of the size of the openings on the sieve 3 also depends on the moisture of the plant trichomes, at higher moisture content it is desirable that the openings on the sieve 3 are larger.

The cannabinoid-rich fraction of plant trichomes contains between 15% and 40% of cannabinoids by weight, based on dry weight, and between 0.1% and 0.2% of terpenes by weight, based on dry weight.

The fraction of terpene-rich plant trichomes contains between 0.2 wt% and 0.7 wt% terpenes, based on dry weight, and between 5 wt% and 10 wt% cannabinoids, based on dry weight. The process for pre-treatment of the industrial hemp plant therefore comprises the following steps: a) crushing of the dried plant input material VM (dried industrial hemp plant) in a crusher 1 with a screen and separating the stems with a diameter of 10 mm to 30 mm from the rest of the plant material in a first collection container Zl, the stems constituting a first final fraction Ml of the plant input material VM; b) transportation of the remaining plant material after crushing along the closed conveyor belt 5 to the rotating sieving drum 2; c) sieving the rest of the plant material remaining after crushing in the rotating sieving drum 2 and separating the seeds and smaller stems with a diameter of less than 10 mm from the plant inflorescences and leaves; d) conveying the seeds and smaller stems from step c) along the closed conveyor belt 5 to the cyclone separator 4 and conveying the plant inflorescences and leaves from step c), which were sieved through the rotating drum 2, along the closed conveyor belt 5 to the inclined sieving screen 3; e) separating the seeds and smaller stems from step c) in the cyclone separator 4, wherein the seeds represent a second final fraction M2 of the input plant material VM and are collected in the second collection container Z2, and the smaller stems represent a third final fraction M3 of the input plant material VM and are collected in the third collection tank Z3; f) sieving the plant inflorescences and leaves from step c) on the inclined sieving screen 3 , thereby obtaining two final fractions of plant trichomes, which differ from each other in terms of the content of pharmacologically effective cannabinoid and terpene components, whereby a fraction containing mainly cannabinoids, represents a fourth final fraction M4 of the input plant material VM and is collected in the first part Z41 of the fourth collection container Z4, while the fraction containing mostly terpenes represents the fifth final fraction M5 of the input plant material VM and is collected in the second part Z42 of the fourth collection container Z4; g) collecting the material that is not sieved on the inclined sieving screen 3 in the fifth collection container Z5, said material being flowers and leaves containing small amounts of cannabinoids and being the sixth final fraction M6 of the input plant material VM.

The loss of material during the process according to the invention is relatively low, amounting to about 2.08 wt. % of material entering the rotary drum 2. The material loss analysis proved that the process itself is economical in terms of material losses.

The presented process enables precise mechanical separation of cannabis trichomes, as well as all other plant parts according to their use, and replaces, among other things, manual harvesting of inflorescences for the purpose of cannabinoid extraction.

Implementation example

The dried plant of industrial hemp, which was obtained after the harvest (moisture of the material: 4.67 wt. %), was put in the first step into a crusher 1 with a sieve, where we separated the thick stems, with a diameter of more than 10 mm, which represent the first final fraction Ml of dried plant Ml, from other parts of the plant. The material, which remained after the separation of the thick stems, and which represented 100 wt. % by weight in further steps of the process, was then led to a rotating sieving drum 2, where 66.23 wt. % was screened and led onto the inclined sieving screen 3, while 3.33 wt. % remained in rotating sieving drum 2. The loss of material in the mentioned step was 0.77 wt. % by weight. The material remaining in the rotating sieving drum 2 represented seeds and plant stalks. The specified material was fed into the cyclone separator 4 and separated. 5.3 wt. % were represented by small stalks, less than 10 mm in diameter, and represent the third final fraction M3, 27 wt. % were seeds, and represent the second final fraction M2. During the process of using the cyclone separator 4, 0.7 wt. % of material was lost. In the further phase of material separation, the inclined sieving screen 3 was used (the inclination of the sieve used is five degrees), on which 61.13 wt. % remained and represented leaves and flowers containing small amounts of cannabinoids and the sixth final fraction M6. The screened material, which includes two final fractions of plant trichomes, which differ from each other in terms of the content of pharmacologically active components of cannabinoids and terpenes, was 4.49 wt. %. The fraction, which mainly contains cannabinoids and represents the fourth final fraction M4, was 3.74 wt. %. The fraction, which mainly contains terpenes and represents the fifth final fraction M5, was 0.75 wt. %. Material loss at this stage was 0.61 wt. %.

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