Process for obtaining natural rubber

Abstract

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

Description

Technical Field

[0001] The present invention relates to a method for obtaining natural rubber from plant material, the plant material being fed to a ball mill and discharged from the ball mill in a wet phase.

[0002] The present invention further relates to a ball mill for obtaining natural rubber from plant material in a wet phase in continuous operation by means of a drum rotatable about a longitudinal axis by a motor. Background Art

[0003] Methods for obtaining natural rubber from plant material are known.

[0004] A disadvantage of such methods is that only a relatively small amount of natural rubber can be obtained per unit time.

[0005] Against this background, the object of the present invention is to design a method and a ball mill such that a relatively large amount of natural rubber can be obtained efficiently while ensuring high quality of the natural rubber.

[0006] This object is achieved by a method according to the features of claim 1 and a ball mill according to the additional independent claims. The dependent claims relate to particularly advantageous developments of the invention. Summary of the Invention

[0007] Accordingly, the present invention provides a method for obtaining natural rubber from plant material, the plant material being fed to a ball mill and discharged from the ball mill in a wet phase, the plant material being ground in the drum by means of a grinding medium, wherein natural rubber is extracted from the plant material in a continuous process by means of the ball mill.

[0008] In terms of system procurement and system operation, the continuous extraction method achieves a higher plant material throughput compared to the case of known batch systems of equivalent size and equivalent cost.

[0009] The quality of the natural rubber flowing out of the drum during the process can be evaluated. This enables adjustment of the process parameters based on the process results during the process. During the process, process parameters such as the speed of the drum or the volumetric flow rates of the plant material and the wet phase can be adjusted. The quality of the natural rubber can be improved and the utilization degree of the plant material can be increased.

[0010] The continuous process is in particular not a batch process. The continuous process is characterized in that the filling level in the drum remains substantially constant throughout the extraction process, and the supply of the material to be ground and the discharge of the already ground material are part of a constant extraction process. Relatively small process-related fluctuations in the filling level or relatively small process-expected fluctuations in the filling level (up to 30% of the target volume of the plant material in the drum) are consistent with a constant process.

[0011] In an advantageous embodiment, the plant material is preferably continuously fed into the drum via the inlet opening and discharged via the outlet opening, and the inlet opening preferably has a smaller cross-section than the outlet opening. The inlet opening for feeding the plant material and the outlet opening for discharging the plant material allow for a simple flow through the length of the drum. As a result, a constant residence time of the plant material and thus a constant degree of grinding can be achieved. When the feeding is carried out constantly, a particularly constant residence time is achieved. As a result, there is a high degree of utilization of the plant material and a high quality of the natural rubber obtained.

[0012] The natural rubber extracted in this process floats on the liquid phase in the form of thin sheets. In the drum, despite the rotation, there is ultimately a constant volumetric flow rate along the drum, where the flow rate is highest at the surface of the liquid phase. As a result, the already extracted natural rubber is guided through the drum at a higher speed, ground for a shorter time and has a higher quality. It has been found advantageous that the inlet opening has a smaller cross-section than the outlet opening, as this ensures that the plant material flows out of the outlet opening even in the case of a horizontal drum.

[0013] According to another preferred embodiment, the plant material is conveyed towards the outlet opening via the conical region of the drum, and the conical region preferably has an angle of 10° to 170°, more preferably 20° to 150°, and even more preferably 30° to 120°. The conveyance of the plant material towards the outlet opening via the conical region reduces the accumulation of plant material residues in the region before the outlet opening, which have an adverse effect on the quality of the natural rubber. It has been found that an angle of 10° to 170°, in particular 20° to 150°, and more particularly 30° to 120° is particularly advantageous.

[0014] In an advantageous embodiment, the drum is rotated continuously, and preferably the plant material is continuously fed into the drum and / or discharged from the drum. The continuous rotation is carried out with as few interruptions as possible and preferably at a constant target speed. However, relatively short interruptions that have no relevant impact on the process are possible, for example in order to collect samples from the drum or to change the direction of rotation of the drum. The continuous rotation maximizes the proportion of time during which the process takes place and thus maximizes the plant material yield. In addition, the continuous rotation enables the natural rubber to have as consistent a quality as possible. The continuous feeding of the plant material into the drum and / or the discharging from the drum results in a constant volumetric flow rate of the plant material through the drum and thereby enables the natural rubber to have as constant a quality as possible.

[0015] According to another advantageous embodiment, a partial amount of the plant material present in the drum, preferably between 0.05% and 30%, more preferably between 0.25% and 20% and even more preferably between 0.5% and 10%, is removed from the drum or supplied to the drum as a surge flow. Any residues of plant material adhering to the surface of the drum (especially in the region of the outlet opening) can be separated or suspended and washed off.

[0016] In an advantageous embodiment, the plant material is ground by means of the non-metallic surface of the drum and / or the non-metallic surface of the grinding medium of the ball mill. Since the metal surface in contact with the plant material during the grinding process reduces the quality of natural rubber, the quality of natural rubber can be improved by the non-metallic surfaces of the drum and the grinding medium.

[0017] In an advantageous embodiment, the non-metallic surface of the drum and / or the non-metallic surface of the grinding medium is free of iron and preferably free of heavy metals and / or transition metals. Heavy metals and transition metals (especially iron, for example in the form of salts) that can cause a reduction in the quality of natural rubber can be present in the non-metallic surface. As a result, the aging resistance of natural rubber can be particularly improved.

[0018] In an advantageous embodiment, the drum is cylindrical over most of its length, and the longitudinal axis of the drum is horizontal or inclined towards the outlet opening, preferably between 0° and 20°, more preferably between 0° and 15°, even more preferably between 0° and 12°, and even more preferably between 0° and 10°. The horizontal orientation of the longitudinal axis of the drum allows the inlet opening and the outlet opening to be arranged horizontally next to each other at the ends of the drum, and the inlet opening and the outlet opening are concentric with respect to the longitudinal axis. A particularly high filling degree of the drum can be achieved. The inclination of the drum towards the outlet opening allows a higher flow velocity of the plant material in the longitudinal direction of the drum, thus making it possible to reduce the residence time of the plant material in the drum and increase the volumetric flow rate through the drum.

[0019] In an advantageous embodiment, the plant material is ground by means of the ceramic, preferably alumina ceramic, vitreous, mineral and / or polymer surface of the drum and / or the ceramic, preferably alumina ceramic, vitreous, mineral and / or polymer surface of the grinding medium. It has been found that ceramic, preferably alumina ceramic, vitreous, mineral and / or polymer surfaces are particularly suitable as the surfaces of the drum and the grinding medium because they are resistant to the grinding process and have no adverse effect on the quality of natural rubber. It has been found to be particularly advantageous to select the same surface for the drum and the grinding medium, as this results in a surface that is particularly resistant to the grinding process.

[0020] In an advantageous embodiment, the ball mill is a drum mill or a tube mill. It has been found that using a drum mill or a tube mill in the method for obtaining natural rubber produces particularly good results both in terms of the quality of the natural rubber and in terms of the degree of utilization of the plant material and the plant material yield.

[0021] In an advantageous embodiment, the plant material is cleaned and / or pre-crushed before being ground in the ball mill. The pre-crushed plant material preferably has a range of 0.5 mm to 16 mm, and more preferably a range of 1 mm to 8 mm. Cleaning the plant material before grinding it reduces the accumulation of residues in the drum. In addition, the quality of the natural rubber is improved because the adverse effects on the natural rubber due to contamination are avoided. It has been found that pre-crushing results in a better quality of natural rubber. The possible reason is the greater uniformity of the initial size of the plant material at the start of grinding. Pre-crushing homogenizes the non-uniform initial plant material in terms of its size. As a result, the grinding process acts more uniformly on the individual components of the plant material.

[0022] In an advantageous embodiment, the plant material is derived from the plant genus Taraxacum, preferably Taraxacum kok-saghyz (Russian dandelion) or its descendants (hybrids). The plant material essentially comprises roots and hypocotyls. It has been found that Taraxacum, in particular Taraxacum kok-saghyz or its descendants (hybrids), has a particularly high natural rubber content and also has the property of releasing natural rubber particularly efficiently in the method according to the invention.

[0023] In principle, the method according to the invention can be applied to all plant species suitable for obtaining natural rubber.Examples of such plants include members of the Asteraceae family, such as species of the Taraxacum or Scorzonera genera (Scorzonera sp.), in particular Taraxacum kok-saghyz, Taraxacum krim-saghyz, Taraxacum bicorne, Taraxacum brevicorniculatum, or Scorzonera tau-saghyz, Scorzonera Uzbekistanica, Scorzonera teke-saghyz, Scorzonera hispanica, Scorzonera tau-saghyz, or Parthenium incanum (gray Parthenium), or other species such as Apocynum venetum, Asclepias incarnata, Asclepias cornuti, Asclepias sub-lata, Asclepias syrica, Cacalia atriplicifolia, Campanula americana, 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 oleraceus, Teucreum canadense, or species of the Silphium genus (Silphium sp.), or mixtures of these plants and also naturally occurring or cultivated hybrids of the above-mentioned species, in addition to Hevea brasiliensis.

[0024] In an advantageous embodiment, the wet phase comprises plant material and water, and preferably consists of plant material and water. It has been found advantageous to add water to the plant material in order to produce the wet phase, since natural rubber floats on the aqueous solution and can thus be effectively separated from the wet phase. Furthermore, it has been found that water is particularly suitable, since many plant components dissolve in the aqueous solution. Preferably, the wet phase consists of plant material and water, such that separation of water from other liquids can be dispensed with, and a method which is operable in a cost-effective and environmentally friendly manner becomes possible. The evaporation components from the wet phase can enter the environment harmlessly.

[0025] In an advantageous embodiment, a partial amount of the plant material discharged from the drum via the outlet opening is fed to the drum via the inlet opening. A short grinding time for the dissolved natural rubber is beneficial for its quality. However, a short residence time of the plant material reduces the proportion of natural rubber extracted from the plant material. This embodiment enables a high degree of utilization of the plant material and a high quality of the natural rubber to be achieved. A particularly short residence time of the plant material in the drum is selected, and the natural rubber extracted is separated from the remaining plant material after leaving the drum. The extracted natural rubber undergoes a short grinding time. At least a part of the remaining portion of the plant material is re-fed to the inlet opening, and preferably temporarily stored in a material buffer. In this regard, the remaining portion of the plant material can be separated such that in particular the plant material with a high natural rubber content is re-fed to the inlet opening. The degree of utilization of the plant material is increased.

[0026] The invention provides a ball mill which comprises: a grinding medium for obtaining natural rubber from plant material in a wet phase in continuous operation by means of a drum which can be rotated about a longitudinal axis by a motor; an inlet opening arranged on one end face of the drum; and an outlet opening arranged on the other end face of the drum.

[0027] In terms of system procurement and system operation, the ball mill achieves a higher plant material throughput compared to known batch systems of equivalent size and equivalent cost.

[0028] The ball mill together with the novel continuous process enables the quality of the natural rubber flowing out of the drum during the process to be evaluated. This enables the process parameters to be adjusted during the operation of the ball mill based on the process results. During the operation of the ball mill, process parameters such as the speed of the drum or the volumetric flow rates of the plant material and the wet phase can be adjusted. The quality of the natural rubber can be increased and the degree of utilization of the plant material can be increased.

[0029] 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 flows out of the outlet opening even in the case of a horizontal drum.

[0030] In another advantageous embodiment of the ball mill, the drum has an extension element for prolonging the residence time of the plant material in the ball mill. Due to the extension element that can be installed between the inlet element and the outlet element, the drum is extensible, so that the residence time of the plant material in the drum can be increased while keeping other process parameters constant. Alternatively, a higher output of plant material can also be achieved while keeping the residence time constant.

[0031] In another advantageous embodiment of the ball mill, the non-metallic surface is iron-free and preferably also free of heavy metals and / or transition metals, and the non-metallic surface preferably consists of ceramics, preferably alumina ceramics, or materials such as porcelain, vitreous, mineral, and / or polymer materials. Such a surface has proven to be resistant to the grinding process and has not shown any adverse effects on the quality of natural rubber.

[0032] In another advantageous embodiment of the ball mill, the outlet opening can preferably be closed by means of a flap or a valve. This enables the plant material to be discharged as a surge in a simple manner.

[0033] The present invention provides a use of a ball mill according to the present invention, the ball mill comprising a grinding medium for grinding plant material to obtain natural rubber from the plant material, and the ball mill is used in a continuous process.

[0034] The present invention provides a computer program product for carrying out a method according to the present invention for obtaining natural rubber from plant material, the computer program product comprising instructions which, when the program is executed by at least a processor unit, cause the processor unit to carry out the method according to the present invention. Description of the Drawings

[0035] The present invention allows for many embodiments. To further illustrate its basic principles, one of these embodiments is shown in the drawings and will be described below. In the drawings:

[0036] Figure 1 A representation of a method for obtaining rubber with upstream and downstream process steps is shown;

[0037] Figure 2 A cross-section of the ball mill is shown;

[0038] Figure 3 A longitudinal section of the ball mill is shown.

[0039] List of Reference Numerals

[0040] 1 Fresh roots

[0041] 2 Fresh water

[0042] 3 Pretreatment device

[0043] 4 Process water

[0044] 5 Root material

[0045] 6 Extraction step

[0046] 7 Separation step

[0047] 8 Material buffer

[0048] 9 Extraction unit

[0049] 10 Ball mill

[0050] 11 Natural rubber

[0051] 12 Separation unit

[0052] 13 Water treatment section

[0053] 14 Disposal unit

[0054] 15 Drum

[0055] 16 Surface

[0056] 17 Grinding medium

[0057] 18 Conical region

[0058] 19 Outlet opening

[0059] 20 Inlet opening

[0060] 21 Filling neck

[0061] 22 Flap

[0062] 23 Motor

[0063] 24 Processor unit

[0064] 25 Maintenance hole

[0065] 26 Extension element Detailed implementation mode

[0066] Figure 1 A diagram showing a method for obtaining rubber from dandelions with upstream and downstream process steps is shown. In the first process step, fresh roots 1 from dandelions and fresh water 2 are supplied to the pretreatment device 3. In the pretreatment device 3, the fresh roots 1 are washed with fresh water 2 and pretreated through further process steps. In addition, the already treated process water 4 and root material 5 can be supplied to the pretreatment device 3, where the root material has undergone an extraction step 6, followed by separation in a separation step 7 and temporary storage in a material buffer 8.

[0067] After pre-treatment, the root material 5 is fed to the extraction unit 9. In the extraction unit 9 in the form of a ball mill 10, the root material 5 is further comminuted. The root components are separated from each other, and in particular the natural rubber 11 is separated from the remaining root material 5. For this purpose, fresh water 2 or process water 4 is fed to the ball mill 10. After the extraction step 6, the root material 5 and the natural rubber 11 are conveyed to the separation unit 12. The separation unit 12 separates the natural rubber 11 from the remainder of the root material 5. A part of the remainder of the root material 5 is fed together with the process water 4 to the water treatment section 13 and is thereby separated into process water 4 and residues. Then the process water 4 can be fed to the pre-treatment device 3. The process water 4 can be fed from the extraction unit 9 to the water treatment section 13.

[0068] A second part or all of the material of the remainder of the root material 5 and the process water 4 can be fed from the separation unit 12 to the disposal unit 14. Process water 4 is additionally fed from the pre-treatment device 3 to the disposal unit 14.

[0069] A third part of the remainder of the root material 5 or all of the material from the separation unit 12 can be fed to the material buffer 8 and can be further conveyed from the material buffer to the pre-treatment device 3 or into the extraction unit 9.

[0070] Figure 2 A cross-section of the drum 15 of the ball mill 10 is shown. The drum 15 has an inner surface 16 which comes into contact with the grinding medium 17 and grinds the root material 5. The surface 16 and the grinding medium 17 are composed of alumina ceramics. On the outlet side, the drum 15 has a conical region 18 leading from the cylindrical region to the outlet opening 19, and the outlet opening 19 has a larger diameter than the inlet opening 20.

[0071] Figure 3Shows a longitudinal section of the drum 15, as shown on the left side. The drum has an inlet opening 20 through which the root material 5 is supplied by means of a filling neck 21. The root material 5 is conveyed into the drum 15 via a screw conveyor. The drum 15 has an inner surface 16 which is cylindrical over most of the length of the drum 15. After the cylindrical region is a conical region 18 of the surface 16 which connects the cylindrical region to the outlet opening 19. At the outlet opening 19 there is a flap 22 by means of which the outlet opening 19 can be closed. By setting the filling level in the drum 15 such that the root material 5 and the natural rubber 11 abut against the flap 22 and the flap is opened, a flow of the root material 5 and the natural rubber 11 can be released. There is a grinding medium 17 in the drum 15 for grinding the root material 5. The drum 15 is driven by a motor 23. The motor 23 and other actuators (such as pumps) are controlled by a processor unit 24. A maintenance hole 25 enables maintenance work to be carried out inside the drum 15 in a simple manner. The drum 15 has an extension element 26 which can be arranged in the central region of the drum 15 between the inlet opening 20 and the outlet opening 19. The drum 15 can be used in different lengths, thereby enabling the residence time of the root material 5 in the drum 15 to be changed.

Claims

1. A method for obtaining natural rubber (11) from plant material, feeding the plant material to a ball mill (10) and discharging it from the ball mill (10) in a wet phase, grinding the plant material in a drum (15) by means of grinding media (17), characterized in that the natural rubber (11) is extracted from the plant material by means of the ball mill (10) in a continuous process.

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

3. The method according to any one of the preceding claims, characterized in that the plant material is conveyed through a conical region (18) of the drum (15) towards the outlet opening (19), the conical region (18) preferably having an angle (α) of from 10° to 170°, more preferably from 20° to 150°, and even more preferably from 30° to 120°.

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

5. The method according to any one of the preceding claims, characterized in that a partial amount of the plant material present in the drum (15), preferably between 0.05% and 30%, more preferably between 0.25% and 20%, and even more preferably between 0.5% and 10%, is removed from or fed to the drum (15) as a surge.

6. The method according to any one of the preceding claims, characterized in that the plant material is ground by means of a non-metallic surface (16) of the drum (15) and / or a non-metallic surface (16) of the grinding media (17) of the ball mill (10).

7. The method according to any one of the preceding claims, characterized in that the non-metallic surface (16) of the drum (15) and / or the non-metallic surface (16) of the grinding media (17) is free of iron and preferably free of heavy metals and / or transition metals.

8. The method according to any one of the preceding claims, characterized in that the drum (15) is cylindrical over most of its length, the longitudinal axis of the drum (15) being horizontal or inclined towards the outlet opening (19), preferably at an inclination between 0° and 20°, more preferably between 0° and 15°, even more preferably between 0° and 12°, and even more preferably between 0° and 10°.

9. The method according to any one of the preceding claims, characterized in that the plant material is ground by means of a ceramic, preferably alumina ceramic, vitreous, mineral and / or polymer surface (16) of the drum (15) and / or a ceramic, preferably alumina ceramic, vitreous, mineral and / or polymer surface (16) of the grinding media (17).

10. The method according to any one of the preceding claims, characterized in that the ball mill (10) is a drum mill or a tube mill.

11. The method according to any one of the preceding claims, characterized in that, the plant material is cleaned and / or pre-crushed before grinding in the ball mill (10), the pre-crushed plant material preferably has a range of 0.5 mm to 16 mm, and more preferably has a range of 1 mm to 8 mm.

12. The method according to any one of the preceding claims, characterized in that, the plant material is derived from the plant genus Taraxacum (dandelion), preferably Taraxacum kok-saghyz (Russian dandelion) or its progeny (hybrids), and substantially comprises roots and hypocotyls.

13. A ball mill (10), the ball mill comprising: grinding media (17) for obtaining natural rubber (11) from plant material in the wet phase in continuous operation by means of a drum (15) rotatable about a longitudinal axis by a motor (23); an inlet opening (20) arranged on one end face of the drum (15); and an outlet opening (19) arranged on the other end face of the drum (15).

14. The ball mill (10) according to any one of the preceding claims, characterized in that, the inlet opening (20) has a smaller cross-section than the outlet opening (19).

15. The ball mill (10) according to any one of the preceding claims, characterized in that, the drum (15) has an extension element (26) for prolonging the residence time of the plant material in the ball mill (10).

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