Device and method for rounding graphite flakes of a graphite material

Abstract

Device for rounding a graphite-based material, comprising a working chamber in which the rounding takes place, a feeding device for supplying the graphite-based material into the working chamber; a plurality of rotating rounding tools in the form of beaters located in the working chamber, arranged on a disk rotating about an axis of rotation and in one direction of rotation, preferably with at least one guide apparatus and with a separating device for separating fine and ultrafine material, with a product outlet and preferably with a cover ring arranged above the rounding tools, wherein the disk carries at least 40, better at least 45 and preferably at least 55 beaters per circumferential meter.

Description

[0001] The present invention relates to a device for rounding graphite flakes of a graphite material according to the features of the independent claims. TECHNICAL BACKGROUND

[0002] Lithium-ion batteries are currently used in a wide variety of electrical devices, such as laptops, power tools, and automobiles. Graphite is typically used as the anode material because it has good electrical conductivity and is therefore well-suited for conducting current. Furthermore, the lithium ions can readily bind to the graphite's lattice structure during charging.

[0003] One problem with using graphite as an anode material is that graphite typically occurs in nature as flake graphite, while spherical graphite is significantly better suited for anode applications. Using spherical graphite results in a higher energy density and a longer battery lifespan.

[0004] For the reasons mentioned, flake graphite must be converted into spherical graphite before it can be used as anode material. Based on the Fig. Sections 2A to 2E illustrate the change in graphite morphology during the transformation from flake graphite to spherical graphite. Fig. 2A and Fig. 2B shows graphite in the form of flake graphite, with the in Fig. The flakes shown in 2A are significantly smaller than those in Fig. Flakes shown in 2B. Fig. 2C shows an intermediate stage in which the graphite particles are already partially rounded. Fig. 2D and Fig. 2E finally represents the spherical graphite. STATE OF THE ART

[0005] The conversion of flake graphite to spherical graphite or of green coke to corresponding spherical particles is already known in the prior art and is called spheroidization.

[0006] It should be noted at the outset that wherever graphite material and graphite particles are mentioned below, the corresponding precursors in the form of green coke and the corresponding green coke particles are also included, as are other graphite-based particles. This applies unless it is ruled out that the terms "graphite material" and "graphite particles" are to be understood more narrowly, namely in their literal sense, which is the preferred interpretation. This clarification applies to the entire subsequent text, even if it is not repeated every time.

[0007] In the conversion to spherical graphite, the individual graphite particles are not ground or polished into a spherical shape, but rather spheroidized through a multiple folding process. For this, the individual graphite particles are deliberately set in motion so that they collide with pre-defined obstacles. The kinetic energy applied to the graphite particles is chosen so that they are (ideally) not shattered upon collision, but only deformed. This deformation is called folding.

[0008] Before the flake-like graphite particles are spheroidized, they are usually first subjected to a milling process. This is typically done using a classifier mill. This process step serves to reduce the size of the graphite particles and produce graphite flakes that are small enough to allow the subsequent spheroidization step to produce spherical graphite of the desired quality or fineness class.

[0009] The actual spheroidization process takes place in a spheroidizer. A spheroidizer comprises a work chamber in which the introduced graphite particles are brought into contact with one or more (typically rotating) rounding tools. This contact forces the particles to move towards an obstacle, also known as an impact surface. Upon collision of the particles with this obstacle, the folding process described above occurs.

[0010] To achieve optimal spheroidization, the particles are guided within the spheroidizer by an externally introduced process gas stream in such a way that the particles are repeatedly accelerated by the rounding tools towards the impact surface and folded there. Thus, during the folding process, the particles circulate through the working chamber of the spheroidizer in such a way that all particles are repeatedly accelerated by the rounding tools towards the impact surface.

[0011] After a specific treatment time and a corresponding number of folding cycles, the desired product quality is achieved and the graphite particles have a spherical shape. Since spheroidization involves not only deformation but also, to a small extent, chipping, the spherical graphite particles must ultimately be separated from the resulting fines using an integrated or external classifier.

[0012] One problem with previously known spheroidizers is that the graphite particles are either not only folded, but also unintentionally crushed to a relatively high degree and thus become rejects, or - if the process is set more gently - have to circulate through the working space of the spheroidizer for a relatively long time until all particles are folded or spheroidized to the desired extent. THE PROBLEM UNDERLYING THE INVENTION

[0013] The object of the invention is to provide a device to make a batch process for the spheroidization of fine powders even more efficient. INVENTIONAL SOLUTION

[0014] According to the invention, this problem is solved by the features of the main claim relating to the device. Accordingly, the problem is solved by a device for rounding a graphite material. The device comprises a working chamber in which the rounding takes place, as well as a feeding device for feeding the graphite material into the working chamber, usually in batches. Furthermore, the device comprises a plurality of rotating rounding tools in the form of beaters located in the working chamber.

[0015] The beaters are arranged on a disk rotating about an axis of rotation and in one direction. Preferably, at least one guide apparatus and a separating device for separating fine and ultrafine material are also provided in the device. Furthermore, the device includes a product outlet and a cover ring located above the rounding tools.

[0016] The device according to the invention is characterized in that the disc carries at least 40, preferably at least 45, and preferably at least 55 spaced-apart beaters per meter of circumference. This rotor design according to the invention allows the material to be retained and stressed for a longer period in the region of the radial inner edge of the beaters. This is advantageous because the collisions occurring here between the particles and the beaters are milder and therefore ideally suited for particle folding without significant particle breakage.

[0017] In principle, it can be said that the inventive design creates a decisive functional difference compared to similar, but only seemingly similar, classifier mills.

[0018] In classifier mills, the intended grinding effect is achieved to a significant extent by the fact that the particles to be ground are captured by the beaters and forcefully thrown radially outwards, in order to then impact with high intensity against the sharply jagged impact surface with which the housing of the classifier mill is equipped and which surrounds the disc with the beaters on its outer circumference like a belt.

[0019] In a spheroidal classifier designed according to the invention, the main point of action is different. It is no longer the impact surface mentioned above, because in a spheroidal classifier according to the invention, this surface is preferably significantly less aggressive. This is because its only task now is to deflect the impacting particles upwards in a substantially fracture-free manner so that they are recirculated, i.e., they collide again with the radially inner end of the beaters from a radially inward direction in order to be folded further. Instead, the main point of action in a spheroidal classifier according to the invention is the radially inward first sixth and, even better, the inward first tenth of the paddles and ideally the rounding found there.

[0020] In the area just defined, a smaller relative velocity difference exists between the beater and the respective particle. Therefore, the momentum is no longer sufficient for breakage. Furthermore, due to the curvature on the inside of the beaters, there is a velocity component after contact that points inwards towards the classifier wheel. This keeps the particles on the inner edge of the beaters for a longer period, and, due to the large number of beaters according to the invention, results in an extremely high number of light, non-combustion-effective contacts. These contacts can also cause the particles to spin, which should be advantageous for a folding process. THE FURTHER INVENTIONAL SOLUTION

[0021] The aforementioned problem is further solved by a process for rounding a graphite material, which will be implemented at a later date. In this process, the graphite material comes into contact with at least one rounding tool selected from a plurality of rotating rounding tools. These tools are positioned particularly close together in the circumferential direction, with approximately 40 to 80 rounding tools or beaters positioned side by side per meter of circumference of the beater wheel. Ideally, a cover ring is also arranged above the rounding tools. This cover ring limits the space for the process airflow carrying the graphite material and increases the number of contacts between the graphite material and the at least one rounding tool.

[0022] The inventive method and the machine used for this purpose enable the simple and cost-effective production of rounded graphite particles optimized for battery manufacturing. In particular, the graphite flakes are rounded by folding the corners of the graphite flakes and wrapping them around the core of the graphite flakes. PREFERRED DESIGN OPTIONS

[0023] There are a number of possibilities to design the invention in such a way as to further improve its effectiveness or usability.

[0024] It is therefore particularly preferred that the side surfaces or flanks of some or all clubs have a tangent in their entirety or at least at their radially outward end which forms an angle ALPHA with the radial at its tangent point.

[0025] In this design, the graphite particles are not largely flung radially outwards, but rather strike the inner surface of the housing and the impact or deflection surface formed there at an angle. This improves the return transport of graphite particles flung radially from the beater wheel into the working chamber.

[0026] The ALPHA angle is preferably below 25°. In individual cases, however, angles up to 40° are also useful.

[0027] In another preferred embodiment, the beaters are formed by plates that are curved outwards in an arc.

[0028] This prevents the particles from being flung primarily radially, but rather with a circular motion component. This imparts increased spin to the particles. This spin also improves the return transport of graphite particles flung radially from the beater wheel into the working area.

[0029] Ideally, for the majority of the beaters, or for all beaters, the ratio of beater length to beater width should be greater than 5, and preferably greater than 10. This ensures that the beaters have sufficient radial extension to accelerate multiple graphite particles simultaneously. This increases the processing speed of the device. At the same time, a relatively large number of beaters can be provided on the disc without reducing the spaces between them too much and thus unduly impeding the free circulation of the graphite particles through the working area.

[0030] The "racket length" is the extension of the racket from the end facing the axis of rotation of the disc to the end facing away from the axis of rotation of the disc.

[0031] The "racket width" is the average extension of a racket from the side facing a first immediately adjacent racket to a second immediately adjacent racket of the same racket.

[0032] Preferably, the radial length of the beaters and / or the distance between immediately adjacent beaters and / or the height of the beaters in the direction of the axis of rotation is chosen such that the majority of the impact events between the particles to be rounded and the beaters take place in the area of ​​the radially inward first eighth, or better yet in the area of ​​the inward first ninth of the beaters.

[0033] In this radially inner area of ​​the beaters, impacts predominantly occur that are insufficient to break up the particles. Therefore, this area is avoided as much as possible in classifier mills, since it is ineffective for grinding and is thus not configured as the primary collision zone. For this reason, the beaters in classifier mills are positioned significantly further apart circumferentially. This allows the particles to penetrate deep enough into the area between the beaters to receive a shattering impact from the lateral flank of the beater.

[0034] The spheroidal classifier according to the invention is different. Here, the pumping action of the disc fitted with the beaters can be easily adjusted by experimenting with the parameters specified in the claim, comparable to the known adjustment of the pumping action of a centrifugal pump. With the pumping action correctly adjusted, the majority of the impacts between the particles to be rounded and the beaters occur in the desired radially inward entry region of the beaters, where the impacts are sufficiently intense to cause folding, but not aggressive enough to break up a significant proportion of the particles.

[0035] Preferably, the ratio of the radially measured beater length to the outer radius of the rotatable disc carrying the beaters is between 0.1 and 0.25, and preferably less than 0.2. Maintaining this ratio ensures that the intensity with which the beaters act on the particles is sufficient to achieve folding with good yield, without unacceptable particle breakage and thus rejects.

[0036] Ideally, the height of the paddles changes from their radially inward end to their radially outward end, preferably such that there is a height reduction of 10% to 40% from the radially inward end to the radially outward end of each paddle. This allows the velocity, and thus usually also the volume flow between the paddles, to be kept constant. Of particular interest is limiting the pumping effect that occurs between adjacent paddles, in order to prevent the particles from being drawn in too strongly and the main collision zone from shifting too far radially outward.

[0037] Preferably, the effective diameter of the classifier wheel for classification should be 20% to 50%, and preferably only 20% to 35%, of the outer diameter of the disc on which the beaters rotate. This ensures that the classifier wheel does not come into unnecessary contact with the (not to be classified) ring of particles undergoing spheroidization, and that it does not impart energy to the particles through impacts that are not useful or even detrimental to folding.

[0038] In a further preferred embodiment, the impact surface, which is preferably formed by an area of ​​the cylindrically shaped inner surface of the housing and against which the particles are flung when leaving the gap between adjacent beaters, is smooth or edgeless and corrugated. This eliminates the risk of a large number of particles or particle fragments shattering upon impact with the edges of the impact surface. This would increase the reject rate and reduce the efficiency of the device.

[0039] This problem is effectively addressed by a smooth or corrugated impact surface in the area of ​​the inner surface of the housing. It should be noted that, unlike in a classifier mill, the impact surface in a spheroidal classifier of the type according to the invention does not serve to crush particles by impact, but rather acts as a rotation brake for the rotating stream of particles to be folded.

[0040] Preferably, the guide assembly formed by the guide elements terminates flush with the inner edge of the paddle. This prevents the graphite particles from flowing past the paddles without coming into contact with them. Instead, each particle is accelerated by the paddle as it flows past, causing it to fold. This embodiment thus increases the efficiency of the device.

[0041] In another preferred embodiment, the rounded graphite material is guided without twisting to a separating device of the apparatus. This ensures that the folded particles, as well as the chipped fine and ultrafine material, flow optimally towards the separation device. Therefore, this design increases the efficiency and effectiveness of the separation device.

[0042] Alternatively, it can be provided that the device is operated for a defined time after complete filling, i.e. after reaching the first switch-off value, which has been determined empirically in advance, for example, and after which the rounding of all graphite flakes is reliably completed.

[0043] To further optimize the process conditions, it can be provided that the speed at which the rotating disk, and thus the rounding tools, are moved can be varied during operation. For example, it can be provided that a low rotational speed is initially selected, which is then increased to a maximum rotational speed during operation.

[0044] Alternatively, for certain processes it may also be advantageous to start at a high speed and reduce it during operation.

[0045] Preferably, the device is operated with a maximum rotational speed of the rotating disk between 60 meters per second and 120 meters per second (based on the circumference of the disk). GENERAL

[0046] Despite its superficially similar structure, a spheroidal classifier according to the invention functions fundamentally differently from a classifier mill, and this is also reflected in different physical characteristics.

[0047] A first, and in itself significant, difference is the fact that a classifier mill operates continuously. Coarse material to be ground is continuously fed in, and finished fine material is continuously removed via the classifier.

[0048] The spheroidizer according to the invention operates differently. It works in batch mode and is designed accordingly. At the beginning of the process, the entire quantity of material to be spheroidized in this cycle is fed into the spheroidizer. The material is then processed in the spheroidizer until it has achieved—at least substantially—the desired degree of rounding. During processing, material that has become too small due to unintended crushing rather than folding is "sorted out" by the spheroidizer. In this respect as well, the spheroidizer according to the invention differs from a classifier mill, in which the usable material is removed by the classifier.

[0049] In principle, for a spheroidal classifier according to the invention, the rounding process must always be carried out with a product- and fineness-dependent impulse, otherwise the particles will be crushed during the process. This must be avoided at all costs. Process integration of grinding and rounding is the basis for cascade processes, but cannot be specifically utilized in batch processes.

[0050] It has also been shown that a targeted intensity distribution of the impulse has a positive effect on product quality. The process is most easily described by folding a very thin book or, for a simpler visualization, a single sheet of paper. On the one hand, stronger stresses are needed to fold many layers simultaneously, and on the other hand, lighter stresses are required to smooth the surface and, if necessary, press any protruding sheets against the ball. Ideally, the stresses should never, if at all, occur at a 90° angle to a tool, as this usually results in breakage rather than folding. It is also easy to imagine that a particularly high number of stresses produces a particularly smooth sphere. Experiments have also shown that the final folding step, in particular, requires a lot of energy. This, too, is easily understood using the book example.Each folding process requires a little more force, and the last one is particularly difficult. Therefore, for truly three-dimensional particles, a broad stress distribution below the breaking point is ideal. The number of contacts should be maximized.

[0051] In summary, a spheroidizer according to the invention is designed such that the stresses to which it subjects the particles to be spheroidized are essentially below the stress intensity that leads to particle breakage. In most cases, the spheroidizer is designed such that the number of impacts to which a particle to be spheroidized is subjected is increased over the duration of the batch, compared to a similar classifier mill. LIST OF FIGURES Fig. Figure 1 shows a device according to the invention in schematic representation. Fig. Figures 2A to 2E show the graphite material before, during and after processing within a device according to the invention. Fig. 3A and Fig. 3B shows a horizontal section through the device according to the invention. Fig. 1 and thereby make the racket wheel or a close-up of it visible. Fig. Figure 4 shows a magnified view of the casing. Fig. 1. Fig. Figure 5 shows a partial enlargement from Fig. 1. Fig. 6 shows one of the Fig. 3A and Fig. 3B shows an alternative racket wheel, with rackets that are all the same thickness in the circumferential direction. Fig. 7 shows a side view of the Fig. 6. Fig. 8 shows one of the Fig. 3A and Fig. 3B and Fig. 6, Fig. The 7th racket wheel shown is an alternative racket wheel, with rackets that are straight in themselves but angled. Fig. 9 shows a side view of the Fig. 8. Fig. Figure 9a shows another preferred embodiment of the racket wheel. Fig. 10 shows one of the Fig. 3A and Fig. 3B, Fig. 6, Fig. 7 and Fig. 8, Fig. The 9 shown racket wheel (occasionally also called rounding disc) is an alternative racket wheel with rackets that are curved in on themselves. Fig. 11 shows a detailed view of the Fig. 10. EXAMPLE OF EXECUTION

[0052] The following will initially explain the functionality solely based on the Fig. 1-5 explained. The ones in the Fig. The embodiments shown in 6-11 will be explained later.

[0053] First, the basic functionality of the spheroidal classifier according to the invention is explained; only then are individual measures according to the invention discussed in more detail.

[0054] Fig. Figure 1 shows a device 1 according to the invention for rounding graphite flakes GF of a graphite material GM.

[0055] The device 1 comprises a housing 2 designed approximately as a vertical cylinder, on the top of which a feed device 3 is arranged for the batch feeding of the graphite material GM or green coke. If a graphite material is fed, it usually consists at least substantially of graphite flakes GF. In particular, in the illustrated embodiment, the feed device 3 is designed as a downpipe; however, it can also be provided that the graphite material GM is fed via an injector feed.

[0056] The graphite material GM flows downwards towards the bottom of the working chamber 40. There, it strikes the rounding tool from its radially inward side. The rounding tool consists of beaters 5 attached to a disc-shaped carrier or disk 74, which rotates together with the carrier plate or disk 7 – this configuration can be described as a beater wheel. When the graphite flakes strike the beaters in the region of their radially inward end, i.e., in the region of the rounded end face of the beaters, they are folded according to the invention. A significant portion of the graphite flakes is then thrown back into the process chamber 40 in a radially inward direction, before approaching the radially inward end of the beater wheel and the beaters attached to it once again, where they are folded.Graphite particles that have overcome the radially inward region (generally speaking: optionally about the innermost 1 / 5, better the innermost 1 / 8 of the beater wheel) of the beater wheel in a radially outward direction are transported outwards by the beaters, which, due to their particularly dense arrangement according to the invention, act like centrifugal pumps, without any further collisions to a significant extent taking place between the beaters 5 and the graphite particles, and leave the beater wheel at its outer circumference.

[0057] In this process, the graphite particles also come into contact with the inner surface of the outer wall of the housing 2 of the spheroidal classifier, or with the impact surface 6 located there, which may often be an independent ring component. Generally, and not only for this embodiment, the impact surface (unlike in a classifier mill) is not designed in such a way as to cause collisions that shatter the graphite particles. Instead, according to the invention, the impact surface is designed so that it essentially prevents shattering of the process airflow PL (see Fig. (1, right side of image) supports the upward conveyance of the graphite particles through the "chimney" formed by the air guide ring 15 and the air guide elements 25, and finally discharges them radially inwards back into the process chamber 40. In the process chamber 40, the graphite particles sink back to the bottom. Under the influence of centrifugal force, they move outwards again. As soon as they reach the bottom of the process chamber, they come into contact with the beater wheel or its beaters in such a way that they are folded again.

[0058] Debris of graphite particles that have been unintentionally crushed experience only lower centrifugal forces and are therefore carried into the interior of the classifier wheel 11 by the process airflow PL entering the separation device 10 or its classifier wheel 11 and thus discharged via the separation device 10.

[0059] The separating device 10 is arranged above the disc 7 with the rounding tools 5. The classifier wheel 11 is connected to a second drive 13 via a second drive shaft 12. In particular, it is provided that the first drive shaft 8 and the second drive shaft 12 are arranged coaxially.

[0060] For the sake of completeness, it should also be mentioned that the aforementioned process air is routed as follows: Process air PL is supplied from bottom to top via a supply nozzle 14 in the lower area of ​​the device 1, in particular below the rotating disk 7 with the rounding tools 5. This air is directed to the rounding area and via the guide elements 25 to the separating device 10. The process air PL carries along the fine material and / or very fine material FM, whose centrifugal forces are insufficient to escape the transport action of the process air, and carries this material away from the device 1 via the extraction nozzles 16.

[0061] The Fig. 3A shows a horizontal longitudinal section through the structure, primarily based on the Fig. 1 and Fig. 5. The discussed embodiment. Fig. Figure 3B shows a close-up of this.

[0062] Good in Fig. 3A shows the disc 7, which together with the beaters 5 forms the beater wheel that rotates in the housing 2.

[0063] This is also clearly visible in Fig. 1 and Fig. Figure 5 shows the guide element 25, which is held in place by its arm-like, angled sections 27. It is also clearly visible how the ring-shaped area between the radially inward end of the beaters 5 and the classifier wheel 11, or rather its axial downward projection, forms the process chamber 40.

[0064] It is immediately noticeable that disc 7 is particularly densely packed with clubs. Until now, it was always assumed that the club density in the circumferential direction had to be significantly lower, typically well below 35 clubs, to be maintained around 360°. This, according to the now-proven incorrect assumption, would result in more intense collisions between the clubs and the graphite particles due to the larger gaps between successive clubs.

[0065] Within the scope of the invention, it was recognized that smaller gaps between circumferentially successive bats are able to ensure a more efficient but gentle folding (with less breakage and therefore less waste).

[0066] Against this background, the following applies here, for this exemplary embodiment and more generally: • that the smallest distance between two immediately adjacent rackets 5 is preferably less than the maximum width of a racket in the circumferential direction; • that the vast majority of the rackets 5 are particularly slim, in the sense that the maximum racket width in the circumferential direction corresponds to at least 6 times, or better at least 8 times, the maximum racket length in the radial direction; • that in the circumferential direction of the beater wheel, several slender beaters 5 positioned directly next to each other are followed by a beater 5a with a greater width, which preferably has at least one, better at least two, screw holes for fastening the cover ring 18 that covers the beaters 5, 5a upwards, see the in Fig. 1 shown cover ring 18; • that the bats 5 are designed such that they are further apart in the circumferential direction at their radially outward end than at their radially inward end; • that the bats have a radially inward rounded, preferably substantially semicircular end and are preferably also designed in this way at their radially outward end; • that the rackets each have a constant thickness in the circumferential direction; • that the paddles have smooth side faces, so that adjacent paddles form a radial channel that carries away graphite particles that have left the radially inward area of ​​the paddles, which is predestined for folding, in a radially outward direction in a laminar flow - at least without any significant further collisions between the paddles; • that the beaters are positioned so close together in the circumferential direction and preferably also rotate so quickly that the particles, on their way to or into the beater wheel, predominantly or substantially all collide with the rounded radially inward end of the beaters described above. • The beaters must be designed to be so thick in the circumferential direction that they can form such a pronounced rounding at their radial end that the particles, on their way to or into the beater wheel, predominantly or substantially all collide with the rounded radially inward end of the beaters described above.

[0067] The rackets 5 are in the in the Fig. 3A and Fig. In the embodiment shown in 3B, each is aligned parallel to the radials of the disk 7, which passes through the apex of the rounding of a beater 5 facing away from the axis of rotation of the disk 7.

[0068] The Fig. 6 and Fig. Figure 7 shows a variant of the racket wheel that is only equipped with identical rackets, which, as in Fig. 3, each completely radially aligned. Otherwise, this variant corresponds to the one just described using the Fig. 3 described embodiment, so that (apart from the thicker rackets) everything said above also applies here.

[0069] It is also worth noting that the Fig. 6 with the radius RH and the imaginary auxiliary circumference line H, to which it points, visualizes where - with appropriately closer spacing and optionally appropriate rounding of the clubs and optionally with possible appropriate adjustment of the rotational speed of the club wheel - the majority of collisions or even essentially all collisions take place, namely in the area of ​​the rounding of the one-sided end of each club.

[0070] The Fig. 8 and Fig. Figure 9 shows a third embodiment. In this racket wheel, the rackets, which are still straight in themselves, are inclined, preferably at an angle of 10° to 25°, or better, only 10° to 17.5° relative to the radial. The inclination is such that the radially inward ends of the rackets lag behind.

[0071] These measures allow the impact effect to be varied and, if necessary, the conveying capacity of the impeller wheel to be influenced, as it still operates like a centrifugal pump. A particularly useful aspect is that the particles that have penetrated the area between the impellers are thrown with a radial outward spin against the impact surface 6, which in many cases makes it easier for the particles to find their way back into the working area. In this respect, reference can be made to the principles already discussed in the section on… Fig. 1 and Fig. 5. Explained, reference is made to the above. As in the Fig. As can be seen in Figure 9a, the rounding disc for the current invention is specially designed. The usual design is a grinding disc as a turned part, onto which the individual beaters are then screwed.

[0072] Disc 74 is now involved in the attachment of the rackets. If one were to attempt to implement the present invention using the usual construction, it would quickly become apparent that the strength of the rackets and screw connections does not allow for rackets as tall and thin as the invention envisages.

[0073] Furthermore, twisted rackets pose a particular problem, as their strength decreases and the forces exerted on them increase. Additionally, due to the high speeds involved, the rackets are the primary wear part. Regularly replacing well over 100 rackets, each secured with two screws, would be extremely time-consuming.

[0074] Therefore, the design is preferably created as described by Fig. 9a shows a universal disc 7 that forms a grinding disc base onto which various beater rings can be screwed. The pre-assembled rings are fastened with the screws 77. The racket rings have the disc 74. Two different racket types are mounted on this. Firstly, mounting racket 5, which, as in the Fig. As shown in Figure 9a, the two components are screwed together, and the other components are push-fit batons that are inserted into grooves in the disc 74 and the cover ring 18. The entire assembly is then screwed tightly together to form a ring. Therefore, if the strength required for screwing together the desired baton geometry is insufficient, they can be pushed together, and only a few of the fastening batons need to be made slightly stronger to hold the assembly together.

[0075] This also results in easier maintenance due to the continuous ring, which can be replaced as a whole.

[0076] The only schematic representations Fig. 10 and Fig. The embodiment of the disk 7 and the beaters 5 shown in Figure 11 differs from the previous embodiment in that the beaters 5 have a curvature. Although this is not shown in the drawing, the radially inward ends of the beaters 5 have rounded edges, as described in detail above in the context of the first embodiment. The beater density is also in accordance with the invention, which is shown in the Fig. 10 and Fig. 11 is also not shown.

[0077] Generally speaking, this variant also corresponds to the one just described above. Fig. 3A, Fig. This corresponds to the embodiment described in 3B, so that (apart from the racket curvature as such) everything said above also applies here.

[0078] The geometry and arrangement of the in Fig. The racket 5 shown in Figure 11 can best be described using the (imaginary) lines r1 and r2. Line r1 represents a radial of the disk 7 extending from the axis of rotation and tangent to the radially inward end of a racket on its rotationally leading side. Line r2 represents the tangent to the radially outward end of a racket on its rotationally leading side. In contrast, the angle Alpha exists between the two lines. The angle Alpha is approximately 10° to 25°, but preferably only 15° to 20°.

[0079] The rackets are preferably curved to a virtually constant degree along their entire length.

[0080] One advantage of this geometry of the beaters 5 is that the graphite particles are subjected to a stronger spin. This, in turn, promotes the return transport of the particles to the working chamber 40 when they strike the impact surface 6. GENERAL

[0081] Although no claim is currently being made to this effect, it should be noted as a precaution that the spheroidal classifier claimed here may also be suitable for folding or rounding other material particles, such as aluminum- or other metal-based particles. Therefore, it is hereby pointed out that the right to replace the term "graphite-based particles" in the claims with the broader term "material particles to be folded" is reserved.

[0082] This note applies to the entire preceding text, even if it is not repeated in each instance. REFERENCE MARK LIST 1 Device 2 cases 3 Task setup 4 Not assigned 5, 5a Rounding tool / club 6 Impact area 7 Disc or carrier plate 8 First drive shaft 9 First drive 10 Separating device 11 Sifter wheel 12 Second drive shaft 13 Second drive 14 inlet ports 15 Air guide ring 16 extraction ports 17 Product outlet 18 Cover ring 19 Second rounding tools 20 Control unit 21 Inner surface area 25 guiding elements 26 guide plates 27 Bent area 30 Fasteners 31 Screw connection 40 Process room / workroom 41 Guide ring 45 gap 50 Side surface facing the axis of rotation 51 Impact area 55 Side surface facing away from the axis of rotation 56 Sub-area 57 Sub-area 60 Conducting apparatus 65 Extraction unit 66 Movable cylinder 66c Movable cylinder in locking position 66o Movable cylinder in open position 67 secondary air intakes 70 Serrated inner surface 71 Corrugated inner surface 73 Main impact surfaces of the bats 74 Disc or disc-shaped support 75 Fasteners / Screws 76 Fasteners / Screws 77 Fasteners / screws 78 Housing part 79 gap 80 Fasteners / Screws 81 bolts A distance AP extraction position B5 Width of the rounding tools D axis of rotation DR Direction of rotation EP End product FM fine material and / or ultra-fine material GF Graphite Flakes GM Graphite Material / Graphite-based Material gGF Large Graphite Flakes kgF Small Graphite Flakes L air L5 Longitudinal axis L56 Length of the trailing section in the direction of rotation L57 Length of the section leading in the direction of rotation RH Radius H Auxiliary perimeter line PL Process Air vGT Rounded graphite particles Ta Tangente r1 Radial / tangent to the inner end of the main impact surface 73 of a racket r2 tangent ALPHA Angle Alpha

Claims

Device (1) for rounding a graphite-based material (GM) with a working chamber (40) in which the rounding takes place, a feeding device (3) for feeding the graphite-based material (GM) into the working chamber (40); a plurality of rotating rounding tools (5) in the form of beaters (5) located in the working chamber (40), arranged on a disk (7) rotating about an axis of rotation (D) and in a direction of rotation (DR), preferably with at least one guide apparatus (60) and with a separating device (10) for separating fine material and ultrafine material (FM), with a product outlet (17) and preferably with a cover ring (18) arranged above the rounding tools (5), characterized in that the disk (7) has at least 40, better at least 45 and preferably at least 55 beaters (5) per meter of circumference. Device (1) for rounding graphite-based material (GM), preferably according to one of the preceding claims, characterized in that the radial length of the beaters (5) and / or the distance between immediately adjacent beaters (5) and / or the height of the beaters (5) in the direction of the axis of rotation (D) is selected such that the majority of the impact events between the particles to be rounded and the beaters (5) take place at the radially inward first sixth, or preferably in the region of the inward first ninth of the beaters (5). Device (1) for rounding graphite-based material (GM) according to one of the preceding claims, characterized in that the ratio of the radially measured beater length and the outer radius of the rotatable disk (7) which carries the beaters (5) is 0.1 to 0.25 and preferably less than 0.

2. Device (1) for rounding graphite-based material (GM) according to one of the preceding claims, characterized in that the height of the beaters (5) changes from their radially inward end to their radially outward end, preferably such that there is a height reduction of 10% to 40% from the radially inward end to the radially outward end of the respective beater (5). Device (1) for rounding graphite-based material (GM) according to one of the preceding claims, characterized in that the effective diameter of the classifier wheel (11) for classification is 20% to 50% and preferably only 20% to 35% of the outer diameter of the disk (7) on which the beaters (5) rotate. Device (1) for rounding graphite-based material (GM), preferably according to claim 1, 2 or 3, characterized in that for the majority or all of the rackets (5) the ratio of the racket length to the racket width is greater than 5 and preferably greater than 10. Device (1) for rounding graphite-based material (GM), preferably according to one of the preceding claims, characterized in that the impact surface (6), which is preferably formed by a region of the cylindrically shaped inner surface (21) of the housing (2), is smooth or edgeless corrugated. Device (1) for rounding graphite-based material (GM), preferably according to one of the preceding claims, characterized in that the guide apparatus (60) formed from the guide elements (25) terminates flush on the inside at the top edge of the beater. Device (1) for rounding graphite-based material (GM), preferably according to one of the preceding claims, characterized in that the main impact surfaces (73) of some or all of the bats (5) have a tangent (r2) in their entirety or at least at their radially outward end which forms an angle Alpha with the radial (r1). Device (1) for rounding graphite-based material (GM), preferably according to one of the preceding claims, characterized in that the beaters (5) are formed by plates which are curved outwards in an arc shape.

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