Method for increasing yield of rounded graphite particles

Abstract

The invention relates to a method for producing graphite particles which are rounded by means of impact and which have defined different fineness grades, by means of a plurality of spherical separators which are connected in series, in which the graphite material to be rounded is pre-comminuted, followed by a first spherical separator producing a graphite material of a first fineness grade which is spheroidized by means of folding, and a second spherical separator producing a graphite material of a second fineness grade which is spheroidized by means of folding. The graphite material is discharged as a final product according to the method, while separating the graphite material that cannot be mainly processed into the graphite material of the first fineness grade as a result of the over-comminution, the separated over-comminuted graphite material being fed to a second spherical separator, in this way, the second spherical separator can produce a graphite material of a second finer fineness grade, which is spheroidized by means of folding, which graphite material is likewise discharged as a final product according to the method.

Description

Technical Field

[0001] The invention relates to a method for rounding graphite particles, by means of which the yield of rounded graphite particles can be increased with a low amount of waste.

[0002] The rounding is also called spheroidization Background Art

[0003] Currently, lithium-ion batteries are the mainstream technology used when a rechargeable battery is needed to power electronic devices, from laptops to hand tools to cars.

[0004] In the prior art, lithium-ion batteries are equipped with anodes made of graphite. On the one hand, the graphite anode has the task of conducting electricity and supplying current to the outside world, and graphite is naturally the most suitable material for this task. In addition, every time the battery cell consumes current, lithium ions flow to the graphite anode via its electrolyte, and the battery cell must store the electrolyte in its grid structure.

[0005] Besides the chemical fineness, the morphology of the graphite also plays an important role.

[0006] Spherical graphite (SPG) is an ideal material for use as an anode material. Its smooth, generally accepted surface with significantly reduced anisotropy can effectively interact with the lithium ions stored in the anode material, thereby providing a high anode charge capacity. In addition, spherical graphite is not prone to exfoliation and the irreversible capacity loss associated with it, so a longer service life can be achieved. Overall, the use of spherical graphite can achieve higher energy density and longer service life.

[0007] In nature, graphite is distributed in rocks, for example as so-called flake graphite, such as Figure 1 shown.

[0008] Untreated flake graphite - in its layered form - displays pronounced basal planes. These planes are parallel to the crystal structure of graphite. Along these planes, graphite behaves as a very good conductor of heat and electricity, while transversely to the basal planes - that is, between the individual planes - graphite can be considered a thermal and electrical insulator. Flake graphite therefore exhibits pronounced anisotropy.

[0009] Therefore, flake graphite must be processed to produce the desired spherical graphite. This is because the basal problem does not exist to a large extent for the spherical graphite. Therefore, spherical graphite is more suitable for electrical applications. Figure 2 An impression of the appearance of a spheroidized graphite material with fineness grade SPG 20 is given.

[0010] Other fineness grades that are often used in practice are fineness grades SPG 22, 18 and 10. As the skilled person knows, for example, fineness grade SPG 20 means that if the material is 50 If the diameter of the graphite material is 20 μm, then 50% of the particles constituting the graphite material have an equivalent diameter of less than 20 μm. Similarly, the same applies to other fineness grades.

[0011] Although this is still a fairly new technology, a corresponding process is known in the prior art. It is called spheroidization.

[0012] Spheroidization is not achieved by grinding or cylindrical grinding of individual particles of flake graphite, for example, but by repeatedly folding the graphite flakes, so-called folding. The folding is achieved by causing the graphite flakes to collide repeatedly with obstacles with a selected kinetic energy, which is selected so that the graphite particles do not break up, but are only folded and thus deformed.

[0013] A cascade of about 20 to 30 separator mills connected in series with an externally generated process gas stream is a common continuous process for graphite spheroidization. Additional separators, filters and fans are also provided between every two consecutive separator mills in the cascade. These separator mills work as follows during continuous operation:

[0014] The first separating mill in the cascade is continuously fed with unprocessed "raw graphite", and only by removing spheroidized graphite of the desired particle size from the last separating mill in the cascade can useful material (Nutzgut), ie graphite material of the desired fineness grade, be obtained.

[0015] The desired roundness and fineness grade can be achieved step by step with the help of separate separating mills.

[0016] If the initially still untreated graphite has been sufficiently spheroidized in the first separation mill so that its size is below a certain value, this spheroidized graphite will be forcibly discharged from the first separation mill together with the fine material that is inevitably generated during the spheroidization process. This discharged spheroidized graphite is then subjected to a further separation and filtration in order to separate the fine material (particles whose size is too small to achieve the intended use) from the reusable graphite material that is to undergo the next rounding step. The fine material is discarded. The remaining graphite material is then supplied to the next separation mill in the cascade, which undergoes the next rounding step and discharges it again once it has reached a certain smaller size.

[0017] In practice, this method is difficult to control due to its deeply intertwined cascades involving different system components, and the discarded fine material accumulates as a no longer usable mixture of various particle sizes.

[0018] Hosokawa Alpine of Augsburg recently described an improved spheroidization method in the industry journal "Carbon", 201(2023)847–855.

[0019] In order to perform spheroidization more efficiently, the following batch manufacturing processes are recommended:

[0020] The raw graphite first undergoes a real grinding process in a separating mill in order to pre-comminute it and produce graphite flakes that are small enough to produce spherical graphite of the desired quality grade or fineness grade in a single subsequent spheroidization step. The graphite material portion pre-ground in this way is then introduced into the now specific separating mill.

[0021] The separating mill is equipped with a device that subjects the graphite particles to multiple foldings, thereby spheroidizing them instead of crushing them unnecessarily. During operation, a strong turbulence is generated inside the separating mill, in other words, it can therefore be managed without externally generated process gas flows. After a certain processing time, the desired degree of spheroidization has been achieved. The particular separating mill is now unloaded. The graphite mixture obtained in this way is fed to a separator, which separates the finished spherical graphite particles from the accompanying fine material that needs to be discarded.

[0022] This method allows for good control and high throughput. The disadvantage is that a large amount of used virgin graphite accumulates as fine material that is too fine to be used further and is therefore discarded. Summary of the invention

[0023] Problem on which the invention is based

[0024] The problem underlying the present invention is to provide a method for spheroidizing which is easy to control and which at the same time enables better utilization of the graphite material used, thereby reducing fine material to be discarded and providing a higher yield of useful material.

[0025] Solution according to the invention

[0026] According to the invention, this problem is solved by means of a spheronization method according to claim 1 .

[0027] The invention relates to a method for producing graphite particles of defined different fineness grades which are rounded by impact action, wherein uniformly pre-comminuted raw graphite is used.

[0028] Therefore, multiple spherical separators connected in series can be used

[0029] The method firstly pre-comminutes the graphite material to be rounded so that it is suitable for producing the coarsest of the different fineness grades to be produced by means of the method according to the invention.

[0030] The pre-crushed raw graphite is then fed into the first spherical separator. As a result, a graphite material of the first fineness grade is produced which is spheroidized by folding. After the batch production time is over, the graphite material is directly discharged from the first spherical separator as a useful material (i.e., the final product), so there is no need to pass through another spherical separator.

[0031] During mass production, the first spherical separator separates fine material via its separating wheel, which fine material cannot be processed into graphite material of the first fineness grade to be produced. This is because the particles of this fine material are too fine. The graphite material constituting the fine material may have partially originated from pre-grinding, but it also partially contains fragments, which are produced in an undesirable manner during the rounding process in the first spherical separator.

[0032] The graphite material separated into fine material is fed to the second spherical separator, whereby a finer second grade of graphite material can be produced and produced, which is spheroidized by means of folding. Preferably, after the batch production time, the finer second grade of graphite material is also centrifuged directly from the second spherical separator as a useful material, i.e., the final product. It then does not pass through a further spherical separator.

[0033] The basic idea of ​​the method according to the invention is therefore to produce spheroidized graphite of different fineness grades using only raw graphite which has been appropriately pre-ground to the coarsest fineness grade. In order to produce a suitable raw material for at least one finer fineness grade, use is made of the fact that the spheroidization of the coarser fineness grade graphite is accompanied by further grinding, which produces fragments. Such fragments which are too small are no longer suitable for the production of coarser fineness grades of graphite. However, such fragments are very suitable for processing into finer fineness grades of graphite.

[0034] This is mainly because a considerable part of the fragments constituting the fine material have already undergone rounding in the first spherical separator, which rounding ends abruptly due to fracture.

[0035] Taking these factors into account, it is obvious that the method used to date - namely, very intensive pre-grinding of the raw graphite in order to be able to produce, for example, a fine grade SPG 10 graphite as a useful material by means of rounding, without first looking at which coarser grade can be initially produced by spheroidization - is wasteful.

[0036] Optional design options of the present invention

[0037] It has been found that when determining the intensity of the pre-crushing or pre-grinding, not only the first spherical separator, which provides the coarsest quality level of graphite material, should be taken into account. Instead, it is meaningful to set the intensity of the pre-grinding or pre-crushing so that more than 50% of the graphite material placed on the first spherical separator can be separated via its separating wheel and can then be placed on the second separator, thereby producing a finer grade of graphite material.

[0038] Another particularly advantageous embodiment is that the blade surface of at least one spherical separator is enlarged so that the quotient of the net volume of the separator chamber and the blade surface is in the range between 0.5 and 2.0. In certain cases, a tolerance of + / - 10% is permitted, but it is preferred to fully or at least substantially comply with the limitations mentioned.

[0039] The net volume of the separation chamber is the total volume of the separation chamber minus the envelope volume of the separation wheel.

[0040] The blade surface is understood to be the surface of the blade which, in the circumferential direction, forms the end face on which the graphite particles impinge and are thus folded.

[0041] In this way, the spheronization process can be accelerated, since more energy can be applied to the material to be spheronized without having to increase the rotation speed, thereby increasing the impact intensity and thus the portion of fine material formed.

[0042] Another design is to reduce the separation wheel diameter so that the quotient of the net volume of the separation chamber (as defined above) and the envelope volume of the separation wheel is between 4.2 and 6.5. In some cases, a tolerance of + / -10% is allowed, but it is best to fully comply with or at least substantially comply with the mentioned restrictions.

[0043] As a result, the space in which the material to be spheronized rotates is enlarged. This allows for a higher load capacity and at the same time increases the flowability of the material to be spheronized in the separation space, which has a positive effect on the folding process and its output. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 Pristine graphite in the form of flake graphite is shown.

[0045] Figure 2 Spheroidized graphite of fineness grade SPG 22 is shown.

[0046] Figure 3 Important details of the spherical separator preferably used here are shown.

[0047] Figure 4 A comparative example corresponding to the applicant's previous method concept, which does not conform to the present invention, is shown in order to compare the yield with the method according to the present invention.

[0048] Figure 5 A first exemplary embodiment of the present invention is shown.

[0049] Figure 6 A second exemplary embodiment of the present invention is shown. DETAILED DESCRIPTION

[0050] Mills and Separating Mills

[0051] The method according to the invention is carried out using a mill connected upstream of the actual rounding process, which comminutes the raw graphite and also substantially homogenizes it, in the sense that the grain size differences that may be encountered in the graphite particle mixture to be subsequently spheroidized are less pronounced.

[0052] Especially for the latter, preference is given to using a separating mill as upstream mill.

[0053] The separation mills mentioned here are a combination of a mechanical impact mill with an integrated dynamic air separator.

[0054] This separation mill is characterized in that a separation wheel rotates in its separation chamber and generates a strong circular vortex in the separation chamber. The graphite particles to be ground are entrained by the circular vortex when they enter the separation chamber. As a result, the graphite particles to be ground are subjected to strong centrifugal forces, thereby substantially keeping the still too large particles radially spaced from the separation wheel to a sufficient extent so that these particles are discharged into the separation wheel receiving the fluid and from there transported out of the separation mill. During the process of its turbulent flow through the separation chamber, the graphite particles collide with the blades and the impact surface and are crushed thereon. The graphite particles that have become sufficiently small after one or more crushings can no longer be continuously moved away from the separation wheel by means of the still small centrifugal force applied thereto, but are discharged into the interior of the separation wheel by means of the flow and are subsequently separated.

[0055] A separating mill which is particularly suitable for this application is, for example, a separating mill of the CSM 900 type produced by the applicant.

[0056] Spherical separator

[0057] The rounding according to the invention is characterized in that the graphite particles are repeatedly folded over in order to obtain their rounded shape. Of course, some fragmentation also occurs as a result. The fragmentation is not intentional, but cannot be completely avoided. However, it can also be said that the graphite particles do not obtain their rounded shape by means of a grinding process.

[0058] The fragments, together with particles that are too small and may still originate from pre-grinding, are discharged through the interior of the separation wheel as so-called fine material. This fine material is characterized by particles that are too small to produce the fineness grade of graphite material that is currently rounded in corresponding spherical separators.

[0059] In terms of its general configuration, the spherical separator used according to the invention is a separating mill, but it is used in an improved manner and / or is operated in an improved manner. A significant improvement is that the spherical separator operates with a process gas stream which is reduced compared to a separating mill. The process gas stream volume of the spherical separator is typically 30% to 10% of the process gas stream volume of a separating mill having essentially the same structure.

[0060] Ideally, such a spherical separator is constructed essentially in the manner described in the applicant's patent application DE 10 2020 100 907 A1, which hereby becomes the subject of the present application.

[0061] However, according to the present invention, it is preferred to use the spherical separator described in said patent application in a structurally modified form, as will be described in more detail below.

[0062] Importantly, the kinetic energy of the graphite particles rotating in the separation chamber of the spherical separator is reduced compared to the operation of the separator mill, so that the graphite particles rotating in the separation chamber are mainly folded and are not substantially further broken up by collisions with the installed paddles and impact surfaces.

[0063] Nevertheless, in order to fold the graphite particles as effectively as possible, it has proven to be particularly advantageous to increase the height of the paddle 5 for carrying out the method according to the invention, which can be achieved in Figure 3 (corresponds to DE 10 2020 100 907 Figure 3 B). Compared with the separation mill and the DE 102020 100 907 derived therefrom, the impact surface is larger. Therefore, when the individual blades 5 rotate in the separation chamber fixed by the screws 30 and collide with the graphite particles, the surface available for head-on collision is increased.

[0064] Ideally, the height of the paddles (depending on the model) is between 10 mm and 100 mm in the case of the separating mill and as shown in DE 10 2020 100907, which is increased by 75% to 110% for the spherical separator according to the invention.

[0065] Preferably, more than 45% of the height of the paddle, viewed in radial direction, is located at the height of the vertical gap of the separating wheel, through which gap the fine material is discharged.

[0066] Optionally, the height of the impact surface 6 can be adjusted as required.

[0067] The enlargement of the blade surface allows more graphite particles to be impacted per unit time, thus further rounding them. As a result, more energy can be applied per unit time without making the individual impacts more severe or causing more unnecessary fragments. This results in faster rounding. In batch manufacturing work, the processing time per batch is thus reduced.

[0068] Furthermore, it has proven to be advantageous to dispense with the cover ring 18, which is particularly useful in DE 10 2020 100 907 A1. Figure 3 Shown in larger illustration in B.

[0069] First Specific Exemplary Embodiment and Comparative Example

[0070] Figure 3 A spheroidization method is shown which has hitherto been achieved by using a spherical separator known from the applicant's DE 10 2020 100 907 A1 patent application and which has also been disseminated by Hosokawa Alpine in a more or less similar form according to the above description (results of internal tests carried out on the subject).

[0071] Specific quality grades of commercially available spheroidized graphite material (SPG) are produced on a separate system that is specially adapted for this purpose.

[0072] For example, if you want to produce graphite materials with fineness grades SPG 20 and SPG 10, you need to do this on two systems, which are configured and operated completely independently of each other, such as Figure 4 shown.

[0073] To produce a graphite material with a fineness grade of SPG 10, the raw graphite is pre-ground with the aid of a separating mill 1 (for example, of the CSM 900 type from Netzsch) until d 50 =10 μm, so that the graphite particles are small enough to produce a graphite material of fineness grade SPG 10 by simple folding with the aid of one of the above-mentioned spherical separators 2.

[0074] For this purpose, pre-ground raw graphite 3 is placed in batches on a spherical separator 2. The pre-ground raw graphite 3 is rotated in the separation chamber for a predetermined time, which is measured so that the graphite particles still located in the separation chamber are spheroidized at the end of the run time and thus meet the quality requirements of SPG 10. During the rotation, fine material (particles that are too small for SPG 10) is permanently removed and discharged via the separation wheel in the above-described manner.

[0075] The second production line uses the same process (completely independent) and produces graphite material with a fineness grade of SPG 20.

[0076] When 1,233 kg / h of virgin graphite was used, the output was 661 kg / h, with a total output of 46.4%.

[0077] The process according to the present invention is different. Figure 5 shown.

[0078] A system consisting of an upstream separation mill and a spherical separator is used, the spherical separator is usually connected directly downstream of the separation mill, and the downstream of the spherical separator is connected to a second spherical separator. The two spherical separators are preferably identical or have the same structure, but are operated at different fineness indicators (other operating parameters → rotation speed, gas volume; another separation wheel). Generally speaking, the spherical separators have the same structure and operate in the same way, unless otherwise specified below.

[0079] Ideally, spherical separators constructed in the manner described in DE 10 2020 100 907 are used for implementing the present invention and therefore also for this exemplary embodiment. Ideally, these spherical separators also include at least one of the improvements described above for DE 10 2020 100 907.

[0080] Here, too, the raw graphite is pre-ground.

[0081] However, in this variant of the invention, the pre-grinding is carried out at least substantially only to a particle size which is the particle size of the finished spheroidized graphite of the coarsest grade which can be produced by means of the system, since, in general, the spheroidization does not lead to a reduction in the usable particles unless fragmentation occurs. 50 Significantly reduced.

[0082] In this case, when the first useful product is a 50 When spheroidizing graphite, the pre-grinding is basically carried out to d 50 = 20 μm particle size. No pre-grinding takes place and the comminution is so severe that graphite material of a finer grade than the graphite produced in the first ball separator can only be rounded directly by means of one of the ball separators used here.

[0083] The pre-grinding is carried out using a separating mill 1 (ideally also a mill of the CSM 900 type from Netzsch).

[0084] According to the invention, as previously described, a plurality of ball separators 2a, 2b are arranged downstream of the separation mill 1. The first upstream ball separator 2a is fed with pre-ground raw graphite, matching the fineness grade to be produced therefrom (e.g., for SPG 20 with d 50 20 μm of the original material), that is, it is best done in batches.

[0085] Likewise, the deposited graphite is rotated in the separation chamber for a predetermined time which is determined so that the graphite particles still in the separation chamber are rounded at the end of the run time to meet the required quality requirements, thus producing a graphite material with a fineness grade of SPG 20.

[0086] A reasonable choice is that the diameter of the separator wheel of the first spherical separator is 15% to 25% smaller than the diameter of the separator wheel of the second spherical separator, except that the spherical separators are mostly (at least substantially) identical in structure.

[0087] It is particularly preferred that the first spherical separator (more precisely: its blades) is driven at a rotational speed which varies during each batch process or which is reduced during the batch process from 100% of the initial rotational speed at the beginning of the batch process, i.e. to a speed of 70% to 40% thereof. It can thereby be controlled, on the one hand, that the first spherical separator actually produces graphite material of the desired fineness grade. It can thereby be controlled, simultaneously or alternately, that the first spherical separator actually outputs a certain type and / or amount of fine material which the second spherical separator can process via the interior of its separating wheel.

[0088] Fine materials (in this example particles that are too small for SPG 20) are permanently removed in the above-described manner during the rotation process. These fine materials consist mainly of particles that are already too small after pre-grinding and particles that are broken up during the spheroidization process in the first spherical separator and thus become too small.

[0089] According to the invention, the fine material is not discarded, but is deposited directly or via an intermediate silo storage onto a downstream spherical separator 2b. The spherical separator 2b, by means of folding, again undergoes the rounding already described of the deposited material, thereby producing a graphite material of a finer grade, ideally several grades lower than the previous grade produced previously, ideally at least 5 μm lower, for example, a graphite material of grade SPG 10. The fine material thus produced is removed again via a separating wheel.

[0090] However, unlike the first spherical separator, the second spherical separator (or its blades) is preferably operated at 100% rotational speed during the entire batch process. However, it can be felt that the amount of gas flowing through the second spherical separator is reduced by 10% to 40% by volume compared to the amount of gas flowing through the first spherical separator.

[0091] Finally, the graphite material having the respectively desired fineness is removed from the separation space of the individual spherical separators, for example in the manner described in DE 10 2020 100 907.

[0092] In order to be able to control the process precisely, it is advantageous to connect only two spherical separators in series in the manner described. In order to be able to process larger masses, a plurality of such systems according to the invention are usually connected in parallel.

[0093] The output is significantly higher. When 960 kg / h of virgin graphite is used, 435 kg / h of SPG 20 and 167 kg / h of SPG 10 are obtained. This corresponds to a total productivity of 62.8%.

[0094] Second specific exemplary embodiment

[0095] Figure 6 A second exemplary embodiment according to the invention is shown. Except for the differences noted below, the arrangement corresponds to the first exemplary embodiment described above. Therefore, the statements made there also apply here, unless otherwise specified by the differences noted below.

[0096] The difference is that only the relatively coarsely pre-crushed raw graphite is used in the first ball separator 2a. In order to produce a certain coarsest fineness grade d on the first ball separator mill with the aid of this system 50 Spheroidized graphite, pre-crushed raw graphite 50 It is best to set it to be 10% to 30% higher than the corresponding fineness grade. In this exemplary embodiment, if you want to produce graphite with a fineness grade of SPG 22, you need to set d 50 Pre-crushed to about 24 μm to about 28 μm. This allows for a higher yield of pre-grinding and a wider fineness distribution.

[0097] The first spherical separator is then operated such that it produces a mixture of two fineness grades, for example graphite material of fineness grades SPG 18 and SPG 22 as product.

[0098] Another special feature of this exemplary embodiment is that the diameter of the separation wheel of the first spherical separator 2a is implemented to be smaller than the diameter of the separation wheel of the downstream spherical separator 2b. In most cases, the separation wheel of the first spherical separator 2a runs at a higher speed than the separation wheel of the downstream spherical separator.

[0099] This makes it possible for the separation space of the first spherical separator 2a to accommodate an increased batch (in terms of weight) of pre-crushed graphite and to round it.

[0100] In the case of this exemplary embodiment, it is also particularly preferred when the first spherical separator 2a (more precisely: its paddles) is operated at a rotational speed which varies during each batch, which leads to the advantages described above.

[0101] The above-mentioned improvement of the separation wheel of the first spherical separator 2a leads to a reduction in its separation limit. However, since separators 4 and 5 are additionally provided here (to be described in detail later), this is not a problem. Separators 4 and 5 make up for this "disadvantage" by ideally utilizing the raw graphite that is pre-crushed to a lesser extent, thereby producing usable graphite materials of different fineness grades, such as graphite materials of fineness grades SPG 18 and SPG 22, in the first spherical separator 2a.

[0102] The product is discharged directly downstream of the first spherical separator 2a. In order to obtain a useful product or end product from it, the product needs to be further processed. For this purpose, a first additional, separate separator 4 is used. The separator now separates mainly rounded graphite particles belonging to the fineness grade SPG 18 from the product. Therefore, part of the useful product or end product is graphite material of fineness grade 18.

[0103] The remaining coarser graphite material produced in the above-described separation process is fed to another separate separator. In this way, the graphite material is separated again, i.e., separated into a batch of graphite material that is coarse enough to be fed again for pre-crushing or pre-grinding, and then separated into a second batch of graphite material, which forms a second useful product or final product, i.e., a graphite material with a fineness grade of SPG 22.

[0104] The fine material removed via the inside of the separation wheel of the first spherical separator 2a is not discarded. Instead, it is further processed by the second spherical separator 2b in the manner already described with respect to the first exemplary embodiment into a graphite material of a finer grade, which, as described above, is usually several grades lower than the last grade of fineness produced previously, for example, here a graphite material of grade SPG 10.

[0105] In order to be able to control the process precisely, in the case of this exemplary embodiment only two spherical separators are connected in series in the manner described. In order to be able to process greater weights, a plurality of such systems according to the invention are usually connected in parallel.

[0106] In this case, this approach can also significantly increase yield:

[0107] When 894 kg / h of virgin graphite is used, 137 kg / h of graphite material of SPG 22, 228 kg / h of graphite material of SPG 18 and 167 kg / h of graphite material of SPG 10 are obtained. This corresponds to a total productivity of 60%.

[0108] Reference numerals list

[0109] 1 Separation mill

[0110] 2 Spherical separator

[0111] 2a First spherical separator

[0112] 2b Second spherical separator

[0113] 3 Pre-ground raw graphite

[0114] 4 First additional separator

[0115] 5 Second additional separator

Claims

1. A method for producing graphite particles of defined different fineness grades which are rounded by impact action, With the help of multiple spherical separators connected in series, It is characterized in that Pre-crush the graphite material to be rounded. Subsequently, a first spherical separator produces a graphite material of a first fineness grade which is spheroidized by folding from the pre-crushed graphite material, and the graphite material of the first fineness grade is discharged as a final product according to the method, At the same time, the graphite material that cannot be processed into the first fineness grade graphite material due to excessive crushing is separated, The separated over-crushed graphite material is supplied to a second spherical separator, from which a second finer graphite material which is spheroidized by folding can be produced, and the second fineness grade graphite material is also discharged as a final product according to the method.

2. The method for producing graphite particles of defined different fineness grades which are rounded by impact action according to claim 1, characterized in that The pre-grinding intensity or pre-crushing intensity is set so that more than 50% by weight of the graphite material placed on the first spherical separator is separated via the separating wheel of the first spherical separator and can then be placed on the second separator, which produces a finer grade of graphite material.

3. The method for producing graphite particles of defined different fineness grades which are rounded by impact action according to claim 1 or 2, characterized in that The two spherical separators are connected in series, wherein each spherical separator produces a final product.

4. The method for producing graphite particles of defined different fineness grades which are rounded by impact action according to any one of the preceding claims, characterized in that The fine material separated by the first spherical separator is placed on the second spherical separator without first being separated and / or filtered again outside the first spherical separator.

5. The method for producing graphite particles of defined different fineness grades which are rounded by impact action according to any one of the preceding claims, characterized in that The product produced by the second spherical separator downstream in the processing chain by means of rounding is a graphite material which is several grades finer than the graphite material of the product produced by the first spherical separator by means of rounding.

6. The method for producing graphite particles of defined different fineness grades which are rounded by impact action according to any one of the preceding claims, characterized in that During the batch process, the separating wheel speed of the first spherical separator can be variably controlled in the process chain, whereas the separating wheel speed of the downstream second spherical separator is preferably kept constant during the entire batch process.

7. The method for producing graphite particles of defined different fineness grades which are rounded by impact action according to any one of the preceding claims, characterized in that The separating wheel diameter of the first spherical separator is smaller than the separating wheel diameter of the second spherical separator downstream in the process chain and / or the separating wheel of the first spherical separator rotates faster than the separating wheel of the second spherical separator downstream in the process chain.

8. The method for producing graphite particles of defined different fineness grades which are rounded by impact action according to any one of the preceding claims, characterized in that A first spherical separator loaded with pre-crushed raw graphite having a d 50 is set to be greater than the coarsest grade of product to be produced by the first spherical separator. 50 10% to 30% higher.

9. The method for producing graphite particles of defined different fineness grades which are rounded by impact action according to any one of the preceding claims, characterized in that The first spherical separator is operated so that its target product can be separated into two ready-to-use graphite quantities consisting of graphite materials of different finenesses, ideally consisting of graphite materials of SPG 18 and SPG 22.

10. The method for producing graphite particles of defined different fineness grades which are rounded by impact action according to any one of the preceding claims, characterized in that The first spherical separator is operated so that, in addition to the fineness grade of graphite material to be produced, its product also includes graphite particles which are separated via an additional separator and then placed again on a pre-crushing device for further crushing and placed again on the first spherical separator.

11. The method for producing graphite particles of defined different fineness grades which are rounded by impact action according to any one of the preceding claims, characterized in that During batch processing, the separating wheel speed of the first spherical separator can be variably controlled in the process chain, whereas the separating wheel speed of the second downstream spherical separator is preferably kept constant throughout the batch processing.

12. The method for producing graphite particles of defined different fineness grades which are rounded by impact action according to any one of the preceding claims, characterized in that At least one spherical separator, preferably two spherical separators, are used, the paddle surfaces of which are enlarged such that the quotient of the net volume of the separator chamber and the paddle surface is in the range between 0.5 and 2.

0.

13. The method for producing graphite particles of defined different fineness grades which are rounded by impact action according to any one of the preceding claims, characterized in that The quotient of the net volume of the separation chamber and the envelope volume of the separation wheel is between 4.2 and 6.

5.

14. An apparatus consisting of a plurality of spherical separators for carrying out the method according to any one of the preceding claims.

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