Process for obtaining natural rubber

Abstract

The invention relates to a process for obtaining natural rubber (11) from plant material, wherein: the plant material is fed to a ball mill (10) in a wet phase and discharged from a ball mill (10); the plant material is ground in a drum (15) containing grinding elements (17); and the natural rubber (11) is extracted from the plant material by means of the ball mill (10) in a continuous process.

Description

[0001] Description

[0002] Process for the extraction of natural rubber

[0003] The invention relates to a process for obtaining natural rubber from plant material, wherein the plant material is fed to a ball mill in a wet phase and is discharged from a ball mill.

[0004] Furthermore, the invention relates to a ball mill for obtaining natural rubber in a continuous operation in a wet phase from plant material, having a drum which can be set in rotation about a longitudinal axis by a motor.

[0005] Processes for obtaining natural rubber from plant material are known.

[0006] Such processes have the disadvantage that only a relatively small amount of natural rubber can be obtained per unit of time.

[0007] Against this background, the object of the invention is to design a method and a ball mill in such a way that larger quantities of natural rubber can be obtained efficiently, while ensuring a high quality of the natural rubber.

[0008] This object is achieved by a method according to the features of patent claim 1 and a ball mill according to the independent claim. The subclaims relate to particularly useful developments of the invention. According to the invention, a method for obtaining natural rubber from plant material is provided, wherein the plant material is fed to a ball mill in a wet phase and removed from a ball mill, wherein the plant material is ground in a drum with grinding media, and the natural rubber is extracted from the plant material by the ball mill in a continuous process.

[0009] The continuous extraction process achieves a higher plant material throughput than conventional batch plants of comparable size and with comparable plant acquisition and operating costs.

[0010] It is possible to evaluate the quality of the natural rubber emerging from the drum during the process. This allows for adjustment of the process parameters during the process based on the process results. Process parameters such as the drum speed or the volume flow of the plant material and the wet phase can be adjusted during the process. This enables an improvement in the quality of the natural rubber and an increase in the utilization rate of the plant material.

[0011] A continuous process is not a Bach process. A continuous process is characterized by the fact that the drum fill level remains essentially constant throughout the entire extraction process, whereby a constant extraction process includes the feeding and removal of the ground material. Minor process-related fluctuations in the fill level, or even minor fluctuations in the fill level of up to 30% of the target volume of plant material in the drum, do not conflict with a constant process.

[0012] In an advantageous embodiment, the plant material is fed into the drum, preferably continuously, via the inlet opening and removed via an outlet opening, wherein the inlet opening preferably has a smaller cross-section than the outlet opening. An inlet opening for feeding and an outlet opening for removing the plant material enable a simple flow along the drum. This enables a constant residence time and thus grinding of the plant material. A particularly constant residence time is achieved if the feed takes place at a constant rate. This achieves a high degree of utilization of the plant material with high quality of the obtained natural rubber.

[0013] The natural rubber extracted in the process floats in the form of flakes on the liquid phase. Despite the rotation, a constant volume flow is achieved along the drum, with the flow velocity being highest at the surface of the liquid phase. As a result, the already extracted natural rubber is conveyed through the drum at a higher speed, milled for a shorter time, and is of higher quality. It has proven advantageous for the inlet opening to have a smaller cross-section than the outlet opening, as this ensures that the plant material escapes from the outlet opening even with a horizontally arranged drum.

[0014] A further preferred embodiment provides that the plant material is conveyed to the outlet opening via a conical region of the drum, wherein the conical region preferably has an angle of 10° to 170°, more preferably of 20° to 150°, and more preferably of 30° to 120°. Conveying the plant material via a conical region to the outlet opening reduces the accumulation of plant material residues in the area in front of the outlet opening, which have a negative impact on the natural rubber quality. An angle of 10° to 170°, in particular an angle of 20° to 150°, and more particularly an angle of 30° to 120°, has proven particularly advantageous.

[0015] In an advantageous embodiment, the drum is continuously rotated, and preferably the plant material is continuously fed into and / or removed from the drum. Continuous rotation is rotation with as few interruptions as possible, preferably at a constant target speed. Shorter interruptions that have no significant impact on the process are nevertheless possible, for example, to take samples from the drum or to change the direction of rotation of the drum. Continuous rotation maximizes the amount of time the process is running and thus the plant material throughput.

[0016] Furthermore, continuous rotation enables the most consistent natural rubber quality possible. Continuously feeding and / or removing plant material to and / or from the drum creates a constant volume flow of plant material through the drum, thus enabling the most consistent natural rubber quality possible.

[0017] A further advantageous embodiment provides that a portion, preferably between 0.05% and 30%, more preferably between 0.25% and 20%, and even more preferably between 0.5% and 10%, of the plant material contained in the drum is removed from or added to the drum in a surge. This enables the detachment or suspension and flushing out of plant material residues adhering to the drum surface, particularly in the area of ​​the outlet opening.

[0018] In an advantageous embodiment, the plant material is ground using a non-metallic surface of the drum and / or a non-metallic surface of the grinding media of the ball mill. Metallic surfaces that come into contact with the plant material during the grinding process reduce the quality of the natural rubber, so non-metallic surfaces of the drum and the grinding media enable an improvement in the quality of the natural rubber.

[0019] In an advantageous embodiment, the non-metallic surfaces of the drum and / or the non-metallic surfaces of the grinding media are free of iron and preferably free of heavy and / or transition metals. Non-metallic surfaces may contain heavy and transition metals, especially iron, for example in the form of salts, which can lead to a reduction in the quality of the natural rubber. This can, in particular, improve the aging resistance of the natural rubber.

[0020] In an advantageous embodiment, the drum is cylindrical over the greater part of its length, wherein the longitudinal axis of the drum is arranged horizontally or inclined towards the outlet opening, preferably between 0° and 20°, more preferably between 0° and 15°, more preferably between 0° and 12° and more preferably between 0° and 10°. A horizontal orientation of the longitudinal axis of the drum enables a horizontal arrangement of the inlet and outlet openings to one another at the ends of the drum, wherein the inlet and outlet openings are arranged concentrically to the longitudinal axis. A particularly high filling level of the drum is made possible. By inclining the drum towards the outlet opening, a higher flow velocity of the plant material in the longitudinal direction of the drum is enabled, so that the residence time of the plant material in the drum can be reduced and the volume flow through the drum can be increased.

[0021] In an advantageous embodiment, the plant material is ground using a ceramic, preferably an aluminum oxide ceramic, glass, mineral, and / or polymeric surface of the drum and / or a ceramic, preferably an aluminum oxide ceramic, glass, mineral, and / or polymeric surface of the grinding media. Ceramic, preferably an aluminum oxide ceramic, glass, mineral, and / or polymeric surfaces have proven particularly suitable as surfaces for drums and grinding media, as they are resistant to the grinding process and have no negative impact on the quality of the natural rubber. It has proven particularly advantageous to select the same surface for the drum and the grinding media, as this creates surfaces that are particularly resistant to the grinding process.

[0022] In an advantageous embodiment, the ball mill is a drum mill or a tube mill. It has been shown that the use of drum mills and tube mills in natural rubber extraction processes leads to particularly good results, both in terms of natural rubber quality and plant material utilization and throughput.

[0023] In an advantageous embodiment, the plant material is cleaned and / or pre-shredded before grinding in the ball mill, wherein the pre-shredded plant material preferably has a dimension of 0.5 mm to 16 mm, more preferably a dimension of 1 mm to 8 mm. Cleaning the plant material before grinding reduces the accumulation of residues in the drum. Furthermore, the quality of the natural rubber is increased because the negative effects of contamination on the natural rubber are avoided. It has been shown that pre-shredding leads to better natural rubber quality. This can be due to a more homogeneous starting size of the plant material at the beginning of grinding. The inhomogeneous plant starting material is homogenized in terms of its dimensions by pre-shredding. As a result, the grinding process has a more uniform effect on the individual components of the plant material.

[0024] In an advantageous embodiment, the plant material originates from the genus dandelion (Taraxacum), preferably Russian dandelion (Taraxacum kok-saghyz), or derivatives (hybrids) thereof. The plant material essentially comprises the roots and the hypocotyl. It has been found that dandelions (Taraxacum), in particular Russian dandelion (Taraxacum kok-saghyz), or derivatives (hybrids) thereof, have a particularly high natural rubber content and furthermore have the property of releasing natural rubber particularly efficiently in the process according to the invention.

[0025] The process according to the invention can, in principle, be applied to all plant species suitable for natural rubber production. Examples of such plants include Hevea brasiliensis and members of the Asteraceae, such as Taraxacum sp. or Scorzonera sp., especially Taraxacum kok-saghyz, Taraxacum krim-saghyz, Taraxacum bicorne, Taraxacum brevicorniculatum, or Scorzonera tau-saghyz, Scorzonera Uzbekistanica, Scorzonera teke-saghyz, Scorzonera hispanica, Scorzonera tausaghyz, or Guayule (Parthenium argentatum), or other species such as Apocynum venetum, Asclepias incarnata, Asclepias cornuti, Asclepias sub-lata, Asclepias syrica, Cacalia atriplicifolia, Campanula america, Chicorium intybus, Chondrilla ambigua, Chondrilla pauciflora, Crysothamnus nauseousus, Cryptostegia grandiflora, Euphorbia lathyris, Lactuca serriola, Lactuca sativa, Parthenium incanum, Pycnanthemum incanum, Solidago altissima, Solidago graminifolia, Solidago leavenworthii, Solidago rigida, Sonchus arvensis, Sonchus oleraceous, Teucreum canadense, or Silphium sp., or Mischungen dieser Pflanzen sowie natürlich vorkommende oder gezüchtete Hybride der vorgenannten Spezies.

[0026] In an advantageous embodiment, the wet phase comprises plant material and water and preferably consists of the plant material and water. Adding water to the plant material to create the wet phase has proven advantageous because natural rubber floats on aqueous solutions and can therefore be effectively separated from the wet phase. Furthermore, water has proven particularly suitable because many plant components dissolve in the aqueous solution. The wet phase preferably consists of plant material and water, thus eliminating the need to separate water from other liquids and enabling a cost-effective and environmentally friendly process. Evaporated components of the wet phase can be released into the environment without harm.

[0027] In an advantageous embodiment, a portion of the plant material removed from the drum via the outlet opening is fed to the drum via the inlet opening. A short grinding time for dissolved natural rubber is advantageous for its quality. However, a short residence time of the plant material reduces the proportion of extracted natural rubber from the plant material. The present embodiment makes it possible to achieve a high utilization rate of the plant material with a high quality of the natural rubber. The residence time of the plant material in the drum is chosen to be particularly short, with the extracted natural rubber being separated from the remaining plant material after leaving the drum. The extracted natural rubber undergoes a short grinding time. The remaining plant material is at least partially fed back to the inlet opening; preferably, it is temporarily stored in a material buffer.The remaining plant material can be separated, allowing plant material with a high natural rubber content to be fed back into the inlet opening. The utilization rate of the plant material is increased.

[0028] According to the invention, a ball mill is provided with grinding bodies for obtaining natural rubber in a continuous operation in a wet phase from plant material with a drum that can be set in rotation about a longitudinal axis by a motor, wherein an inlet opening is arranged on one end face of the drum and an outlet opening is arranged on another end face of the drum.

[0029] The ball mill achieves a higher plant material throughput than known batch plants of comparable size and with comparable plant acquisition and operating costs.

[0030] The ball mill with the new continuous process makes it possible to evaluate the quality of the natural rubber emerging from the drum during the process. This enables the process parameters to be adjusted during ball mill operation based on the process results. During ball mill operation, process parameters such as the drum speed or the volume flow of the plant material and the wet phase can be adjusted. This enables an improvement in the quality of the natural rubber and an increase in the utilization rate of the plant material. In an advantageous embodiment of the ball mill, the inlet opening has a smaller cross-section than the outlet opening. This ensures that the plant material emerges from the outlet opening even with a horizontally arranged drum.

[0031] In a further advantageous embodiment of the ball mill, the drum has an extension element to increase the residence time of the plant material in the ball mill. The extension element, which can be mounted between an inlet and an outlet element, allows the drum to be extended, allowing the residence time of the plant material in the drum to be increased while maintaining otherwise constant process parameters. Alternatively, a higher plant material throughput can be achieved with the same residence time.

[0032] In a further advantageous embodiment of the ball mill, the non-metallic surfaces are free of iron and preferably free of heavy and / or transition metals, with the non-metallic surfaces preferably consisting of a ceramic, preferably an aluminum oxide ceramic or, for example, porcelain, glass, mineral, and / or polymeric material. Such surfaces have proven to be resistant to the grinding process and have shown no negative impact on the quality of the natural rubber.

[0033] In a further advantageous embodiment of the ball mill, the outlet opening can be closed, preferably with a flap or valve. This allows for a simple, gradual discharge of the plant material.

[0034] According to the invention, a use of a ball mill according to the invention is provided, wherein the ball mill has grinding bodies for grinding plant material to obtain natural rubber from plant material, wherein the ball mill is used in a continuous process.

[0035] According to the invention, a computer program product is provided for carrying out a method according to the invention for obtaining natural rubber from plant material, comprising instructions which, when the program is executed by at least one processor unit, cause the processor unit to carry out the method according to the invention.

[0036] The invention is susceptible of numerous embodiments. To further clarify its basic principle, one of these is illustrated in the drawings and will be described below.

[0037] Fig. 1 shows a representation of the rubber extraction process with upstream and downstream process steps;

[0038] Fig. 2 a cross-section of a ball mill;

[0039] Fig. 3 a longitudinal section of a ball mill.

[0040] Figure 1 shows a representation of the dandelion rubber extraction process with upstream and downstream process steps. Fresh dandelion roots 1 and fresh water 2 are fed to a preconditioning device 3 in a first process step. The fresh roots 1 are cleaned in the preconditioning device 3 by the fresh water 2 and preconditioned in further process steps. Furthermore, treated process water 4 can be fed to the preconditioning device 3, as well as root material 5 that has already undergone an extraction step 6 and was subsequently separated in a separation step 7 and temporarily stored in a material buffer 8.

[0041] After preconditioning, the root material 5 is fed to an extraction unit 9. In the extraction unit 9, which is designed as a ball mill 10, the root material 5 is further crushed. The root components are separated from one another, with particular emphasis on separating natural rubber 11 from the remaining root material 5. For this purpose, fresh water 2 or process water 4 is fed to the ball mill 10. Following the extraction step 6, the root material 5 and the natural rubber 11 are conveyed to a separation unit 12. The separation unit

[0042] 12 separates the natural rubber 11 from the further root material 5. The further root material 5 is partly mixed with the process water 4 of a water treatment

[0043] 13, where it is separated into process water 4 and residual materials. The process water 4 can be fed to the preconditioning device 3. Process water 4 from the extraction unit 9 can be fed to the water treatment unit 13.

[0044] A second part of the further root material 5 or the entire material and the process water 4 can be discharged from the separation unit 12 to a disposal unit

[0045] 14. Process water 4 from the preconditioning device 3 is also supplied to the disposal unit 14.

[0046] A third part of the further root material 5 or the entire material from the separation unit 12 can be fed to the material buffer 8 and can be conveyed from there into the preconditioning device 3 or into the extraction unit 9.

[0047] Figure 2 shows a cross-section of a drum 15 of the ball mill 10. The drum 15 has an inner surface 16 which comes into contact with grinding media 17 and grinds the root material 5. The surface 16 and the grinding media 17 are made of an aluminum oxide ceramic. On the outlet side, the drum 15 has a conical region 18 which leads from the cylindrical region to an outlet opening 19, wherein the outlet opening 19 has a larger diameter than the inlet opening 20. Figure 3 shows a longitudinal section of the drum 15, which, shown on the left, has an inlet opening 20 which is fed with root material 5 via a filler neck 21. The root material 5 is conveyed into the drum 15 via a screw. The drum 15 has an inner surface 16 which is cylindrical over most of the length of the drum 15.Adjacent to the cylindrical region is a conical region 18 of the surface 16, which connects the cylindrical region to the outlet opening 19. A flap 22 is provided at the outlet opening 19, with which the outlet opening 19 can be closed. A gush-like release of the root material 5 and the natural rubber 11 is made possible by adjusting the fill level in the drum 15 such that the root material 5 and the natural rubber 11 are against the flap 22 and the flap is opened. Located in the drum 15 are grinding media 17 for grinding the root material 5. The drum 15 is driven by a motor 23. The motor 23 and the other actuators, such as pumps, are controlled by a processor unit 24. A maintenance opening 25 enables easy maintenance work to be carried out inside the drum 15.The drum 15 has an extension element 26 that can be arranged in a central region of the drum 15 between the inlet opening 20 and the outlet opening 19. This allows the use of the drum 15 in different lengths, thereby altering the residence time of the root material 5 in the drum 15.

[0048] List of reference symbols

[0049] 1 fresh roots

[0050] 2 Fresh water

[0051] 3 Preconditioning device

[0052] 4 Process water

[0053] 5 Root material

[0054] 6 Extraction step

[0055] 7 Separation step

[0056] 8 material buffers

[0057] 9 Extraction unit

[0058] 10 ball mill

[0059] 11 Natural rubber

[0060] 12 Separation unit

[0061] 13 Water treatment

[0062] 14 disposal unit

[0063] 15 drum

[0064] 16 Surface

[0065] 17 grinding media

[0066] 18 conical area

[0067] 19 Outlet opening

[0068] 20 Inlet opening

[0069] 21 Filler neck

[0070] 22 flap

[0071] 23 Engine

[0072] 24 processor unit

[0073] 25 Maintenance opening

[0074] 26 Extension element

Claims

Patent claims 1 .A method for obtaining natural rubber (11) from plant material, wherein the plant material is fed to a ball mill (10) in a wet phase and is removed from a ball mill (10), wherein the plant material is ground in a drum (15) with grinding bodies (17), characterized in that the natural rubber (11) is extracted from the plant material with the ball mill (10) in a continuous process.

2. Method according to claim 1, characterized in that the plant material is fed to the drum (15), preferably continuously, by means of the inlet opening (20) and is discharged by means of an outlet opening (19), wherein the inlet opening (20) preferably has a smaller cross-section than the outlet opening (19).

3. Method according to one of the preceding claims, characterized in that the plant material is conveyed via a conical region (18) of the drum (15) to the outlet opening (19), wherein the conical region (18) preferably has an angle (a) of 10° to 170°, more preferably of 20° to 150° and more preferably of 30° to 120°.

4. Method according to one of the preceding claims, characterized in that the drum (15) is continuously rotated and preferably the plant material is continuously fed to the drum (15) and / or removed from the drum (15).

5. Method according to one of the preceding claims, characterized in that a partial amount, preferably between 0.05% and 30%, more preferably between 0.25% and 20% and more preferably between 0.5% and 10%, of the plant material located in the drum (15) is removed or fed into the drum (15) in a surge-like manner.

6. Method according to one of the preceding claims, characterized in that the plant material is ground with a non-metallic surface (16) of the drum (15) and / or a non-metallic surface (16) of the grinding bodies (17) of the ball mill (10). / .Process according to one of the preceding claims, characterized in that the non-metallic surfaces (16) of the drum (15) and / or the non-metallic surfaces (16) of the grinding bodies (17) are free of iron and preferably free of heavy and / or transition metals.

8. Method according to one of the preceding claims, characterized in that the drum (15) is cylindrical over the greater part of its length, the longitudinal axis of the drum (15) being arranged horizontally or inclined towards the outlet opening (19), preferably between 0° and 20°, more preferably between 0° and 15°, more preferably between 0° and 12° and more preferably between 0° and 10°.

9. Method according to one of the preceding claims, characterized in that the plant material is ground with a ceramic, preferably an aluminum oxide ceramic, glass, mineral and / or polymer surface (16) of the drum (15) and / or a ceramic, preferably an aluminum oxide ceramic, glass, mineral and / or polymer surface (16) of the grinding bodies (17). Method according to one of the preceding claims, characterized in that the ball mill (10) is a drum mill or tube mill. Method according to one of the preceding claims, characterized in that the plant material is cleaned and / or pre-comminuted before grinding in the ball mill (10), wherein the pre-comminuted plant material preferably has an extension of 0.5 mm to 16 mm, more preferably an extension of 1 mm to 8 mm. Method according to one of the preceding claims, characterized in that the plant material originates from the plant genus Dandelion (Taraxacum), preferably Russian Dandelion (Taraxacum kok-saghyz) or derivatives (hybrids) thereof, and essentially comprises the roots and the hypocotyl. Ball mill (10) with grinding media (17) for obtaining natural rubber (11) in continuous operation in a wet phase from plant material, comprising a drum (15) that can be set in rotation about a longitudinal axis by a motor (23), wherein an inlet opening (20) is arranged on one end face of the drum (15) and an outlet opening (19) is arranged on another end face of the drum (15). Ball mill (10) according to one of the preceding claims, characterized in that the inlet opening (20) has a smaller cross-section than the outlet opening (19). Ball mill (10) according to one of the preceding claims, characterized in that the drum (15) has extension elements (26) in order to extend the residence time of the plant material in the ball mill (10).

Images