Methods to increase the yield of rolled graphite particles

Abstract

To provide a method for producing spheroidal particles from graphite materials that is easy to control and can leave behind less fine material to be discarded and can provide a higher yield of useful material.SOLUTION: The present invention relates to a method for producing graphite particles of certain, different fineness classes rounded by impact effect, with the help of plural spheroidal separators, which are connected in series, wherein the graphite material to be rounded is pre-comminuted, and a first spheroidal separator then produces graphite material of a first fineness class, which is spheroidized by means of folding, from the graphite material and discharges the resulting graphite material of the first fineness class as end product, and simultaneously separates graphite material, which can predominantly not be processed to graphite material of this first fineness class because it is too comminuted, and feeds the separated graphite material, which is too comminuted, to a second spheroidal separator, and the second spheroidal separator produces graphite material of a second, finer fineness class, which is spheroidized by means of folding, from the separated graphite material and discharges the resulting graphite material of the second fineness class as end product.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] This invention relates to a method for rounding graphite particles that can increase the yield of rounded graphite particles while reducing waste. This rounding process is also called spheroidization. [Background technology]

[0002] Lithium-ion batteries are currently the batteries needed to power electrical devices ranging from laptops and hand tools to automobiles.

[0003] Equipping lithium-ion batteries with a graphite anode is conventional technology. On the one hand, the graphite anode has the role of conducting electric current and supplying it to the outside, and graphite is inherently optimal for this purpose. Furthermore, lithium ions need to flow to the graphite anode each time an electric current flows from the battery cell through the electrolyte, and also need to be stored in the grid structure of the anode.

[0004] In addition to chemical purity, the morphology of graphite also plays an important role.

[0005] Spherical graphite (SPG) is ideal as an anode material. Its smooth surface, with significantly low anisotropy and therefore universally receptive, can effectively interact with the Li ions stored in the anode material, providing high anodic charging capacity. Furthermore, spherical graphite has a lower tendency to delaminate and the resulting irreversible capacity loss, thus achieving a longer service life. Overall, using spherical graphite allows for the achievement of higher energy density and a longer service life.

[0006] In nature, graphite exists, for example, as so-called flake graphite distributed within rocks, as shown in Figure 1.

[0007] Untreated, layered flaked graphite exhibits prominent basal planes. These planes extend parallel to the crystalline structure of the graphite. Along these planes, graphite is not only an excellent thermal conductor but also an electrical conductor, while lateral to the basal planes, i.e., between individual planes, it can be considered both a thermal and electrical insulator. Thus, flaked graphite exhibits remarkable anisotropy.

[0008] For this reason, flaked graphite must be processed to produce the required spherical graphite, because the bottom surface issue is virtually irrelevant to spherical graphite. Therefore, spherical graphite is far more suitable for electrical applications. Figure 2 shows the appearance of spherical graphite material of fineness class SPG20.

[0009] Other finer classes that are frequently required in practice include finer classes SPG22, 18, and 10. As is known to those skilled in the art, finer class SPG20 refers to, for example, material d 50 When it is 20 μm, this refers to the case where 50% of the particles constituting the graphite material have an equivalent diameter smaller than 20 μm. The same applies to other finer classes as well.

[0010] The corresponding processing technique is still relatively new, but it is known from conventional methods. This technique is called spheroidization.

[0011] Spheroidization is achieved not, for example, by grinding or cylindrical grinding of individual particles in flaked graphite, but by so-called folding of graphite flakes multiple times. Folding is achieved by repeatedly colliding graphite flakes, carried by a carrier gas flow or process gas flow, with an amount of kinetic energy selected such that the graphite particles are folded and thus deformed without being ground.

[0012] A cascaded series connection of approximately 20-30 separator mills, to which an externally generated process gas flow is applied, is a common continuous process for graphite spheroidization. Between each pair of separator mills in the cascade, additional separators, filters, and fans are provided. These separator mills operate as follows during continuous operation:

[0013] Untreated "raw graphite" is continuously supplied to the first separator mill in the cascade, and graphite rounded to the desired particle size, in other words, the useful material, i.e., the desired fine class of graphite material, can only be extracted from the last separator mill in the cascade.

[0014] The desired rounding and fineness are gradually achieved by individual separator mills.

[0015] When the untreated graphite is significantly rounded in the first separator mill to a size below a certain threshold, it is inevitably released from the separator mill along with the fine material that inevitably arises during rounding. The graphite is then subjected to further separation and filtration to separate the fine material (i.e., particles already too small to achieve the desired purpose) from the reusable graphite material that will be subjected to the next rounding step. The fine material is discarded. The remaining graphite material is then fed into the next separator mill in the cascade, which will subject the remaining graphite material to the next rounding step and release it again as it reaches an even smaller size.

[0016] This method is difficult to control in practice because the cascade is significantly misaligned, involving different system components. The discarded micromaterials accumulate as a mixture of unusable materials with varying particle sizes.

[0017] More recently, an improved spheroidization method was published in Non-Patent Document 1 (industry journal "Carbon 201 (2023) 847-855") by Hosokawa Alpine, based in Augsburg.

[0018] To achieve more efficient spheroidization, the following batch method has been proposed.

[0019] In this case, the raw graphite is first subjected to the actual grinding process in a separator mill, which pre-grinds the raw graphite to produce graphite flakes. These pre-grinded graphite flakes are small enough to produce spherical graphite of the desired quality or fine class in a subsequent single spheroidizing step. The thus pre-grinded graphite material is then introduced in small amounts into a specific separator mill.

[0020] This separator mill is equipped with a device that folds the graphite particles multiple times to create spheroids, rather than unnecessarily grinding them. This separator mill is said to function without externally generated process gas flow because it generates strong turbulence internally during operation. After a certain processing time, the desired degree of spheroidization is reached. At this point, the contents are removed from the separator mill. The resulting graphite mixture is then sent to a separator, which separates the finished spherical graphite particles from any accompanying fine material that should be discarded.

[0021] This method is well controllable and has high throughput. The drawback of this method is that a considerable amount of the raw material graphite used accumulates as fine material and is too fragmented to be used further, resulting in its disposal. [Prior art documents] [Non-patent literature]

[0022] [Non-Patent Document 1] Carbon 201 (2023) 847 - 855. Hosokawa Alpine, Augsburg

Summary of the Invention

Problems to be Solved by the Invention

[0023] The problem of the present invention is to propose a spheroidization method that is easy to control and at the same time enables better use of the graphite material used, that is, reduces the amount of fine materials to be discarded and increases the yield of useful materials.

Means for Solving the Problems

[0024] According to the present invention, this problem is solved by the spheroidization method according to claim 1.

[0025] The method of the present invention uses uniformly pre-crushed raw material graphite and is for producing specific different fine classes of graphite particles rounded by the impact effect.

[0026] In this case, a plurality of spheroidization separators connected in series are used.

[0027] The method of the present invention starts by pre-crushing the graphite material to be rounded to a degree suitable for producing the coarsest fine class among the different fine classes produced by the method according to the present invention.

[0028] Next, the first spheroidization separator is filled with the pre-crushed raw material graphite. The first spheroidization separator produces the spheroidized first fine class of graphite material from this graphite by folding. After the batch time, this graphite material is discharged from the first spheroidization separator as a useful material, that is, as the final product, and thus does not pass through further spheroidization separators.

[0029] During the batch process, the first spheroidizing separator separates the fine material. This fine material is virtually impossible to process into this first fine class, which the first spheroidizing separator is responsible for producing via its separator wheel. This is because the particles of this fine material are too small. The graphite material that makes up this fine material may be partially derived from pre-grinding, but may also be composed of undesirable fragments generated during rounding in the first spheroidizing separator.

[0030] The graphite material separated as fine material is fed to a second spheroidizing separator, which can produce a finer second-fine class of spheroidized graphite material from the separated graphite material by folding. Preferably, the finer second-fine class of graphite material is also centrifuged directly from the second spheroidizing separator after a batch time as a useful material, i.e., as the final product. The graphite material does not then pass through any further spheroidizing separators.

[0031] Thus, the basic solution concept of the method according to the present invention is to use raw graphite that has been appropriately pre-ground only for the coarsest micrograde in order to produce spheroidized graphite of different microgrades. To produce material suitable for at least one finer micrograde, the fact is taken advantage of that spheroidization of graphite in the coarser micrograde involves certain further grinding, and that this further grinding causes fracture. This fracture is too small to be suitable for producing graphite in the coarser micrograde, but is very suitable for processing graphite in the finer micrograde.

[0032] This is partly due to the fact that a significant portion of the damaged material constituting the micromaterial was already rounded by the first spheroidizing separator, and that this rounding was abruptly terminated by the subsequent damage.

[0033] In light of these considerations, it becomes clear that the conventional approach—namely, first determining how much of a coarser, finer class can be produced—is pointless, as it involves extremely strong pre-grinding of the raw graphite so that a useful material, such as a fine-grade SPG10 graphite, can be produced by rounding.

[0034] When determining the intensity at which pre-grinding or pre-grinding is performed, it has proven particularly advantageous not to consider only the first spheroidizing separator, which provides the coarsest quality level of graphite material. Instead, it makes sense to set the intensity for pre-grinding or pre-grinding such that more than 50% by weight of the graphite material placed in the first spheroidizing separator is separable via the first spheroidizing separator wheel, and then placed in the second separator, which produces a finer, more micron class of graphite material.

[0035] In other design options that are particularly advantageous, the paddle surface in at least one spheroidizing separator is enlarged such that the quotient between the net volume of the separator chamber and the paddle surface is in the range of 0.5 to 2.0. In some cases, a tolerance of + / -10% is permitted, but it is preferable that the stated limits be fully or at least substantially observed.

[0036] In this case, the net volume of the separator chamber is understood to be the total volume of the separator chamber minus the envelope volume of the separator wheel.

[0037] The circumferential end faces, where graphite particles collide and fold, are understood to be paddle surfaces.

[0038] This allows the spheroidization process to be accelerated because more energy can be added to the material to be spheroidized without increasing the speed, thus increasing the impact strength and, consequently, the amount of fine material generated.

[0039] In other design options, the diameter of the separator wheel is reduced to such an extent that the quotient between the net volume of the separator chamber and the envelope volume in the separator wheel is between 4.2 and 6.5 (as specified above). In some cases, a tolerance of + / - 10% is permitted, but it is preferable that the stated limits be fully or at least substantially observed.

[0040] This expands the space in which the material to be sphericalized rotates. This allows for a larger load capacity and, at the same time, improves the mobility of the material to be sphericalized in the separator space, positively impacting the folding process and its yield. [Brief explanation of the drawing]

[0041] [Figure 1] This is an explanatory diagram showing raw graphite existing as flake graphite. [Figure 2] This is an explanatory diagram showing spheroidized graphite of the fine class SPG22. [Figure 3] Preferably, this is a detailed diagram showing an important part of the spheroidizing separator used in relation to the present invention. [Figure 4] This is an explanatory diagram showing comparative examples corresponding to the applicant's prior concepts regarding methods that do not conform to the present invention, in order to enable yield comparison with the method according to the present invention. [Figure 5] This is an explanatory diagram showing a first exemplary embodiment of the present invention. [Figure 6] This is an explanatory diagram showing a second exemplary embodiment of the present invention. [Modes for carrying out the invention]

[0042] To carry out the method according to the present invention, a mill connected upstream of the actual rounding process is used. This mill not only grinds the raw graphite but also, in many cases, homogenizes it in the sense that the differences in particle size in the graphite particle mixture to be later spheroidized become less pronounced.

[0043] In particular, for the latter, a separator mill is preferably used as the upstream mill.

[0044] The separator mills referred to herein combine a mechanical impact mill with an integrated dynamic air separator.

[0045] Such a separator mill is characterized by a separator wheel rotating within a separator chamber, generating a strong circular vortex within the chamber. Graphite particles to be ground are drawn into the circular vortex as they enter the separator chamber. As a result, any particles that are still too large are substantially held in a region sufficiently far radially away from the separator wheel by strong centrifugal force. This is to release these particles into the flow-receiving separator wheel and from there to the outside of the separator mill. The graphite particles are ground by collisions with paddles and impact surfaces as they move turbulently within the separator chamber. After one or more grinding passes, the graphite particles, now small enough that they can no longer be permanently separated from the separator wheel by the smaller centrifugal force acting upon them, are released into the chamber by the flow and then separated.

[0046] A separator mill particularly suitable for this application is the Model CSM900 by the present applicant.

[0047] Spheroidizing separator The rounding method according to the present invention is characterized by the repeated folding of graphite particles, thereby obtaining a round shape. In this case, some degree of breakage (fracture) is inherent. Breakage is not intended, but it cannot be completely avoided. However, it can be said that graphite particles, in particular, do not obtain a round shape through the grinding process.

[0048] The fragments, along with other particles that may be too small, possibly originating from pre-grinding, are released through the separator wheel to form so-called fine material. This fine material is characterized by being too small to produce the fine class of graphite material currently being rounded in each spheroidizing separator.

[0049] The general structure of a spheroidizing separator used according to the present invention is a separator mill, but is used and / or operated with modifications. The key modification is that the spheroidizing separator is operated with a reduced process gas flow compared to a separator mill. The process gas flow of a spheroidizing separator is typically 30% to 10% of the process gas flow in a separator mill having substantially the same structure.

[0050] Ideally, such a spheroidal separator is the subject of this application and is constructed substantially similarly to that described in the German Patent Application Publication No. 102020100907 by the applicant.

[0051] However, according to the present invention, as will be further detailed below, the spheroidizing separator described in the above-mentioned patent application is preferably used in a structurally modified form.

[0052] The key is that the kinetic energy of the spheroidizing separator rotating within the separator chamber is reduced compared to the operation of a separator mill to such an extent that the graphite material rotating within the separator chamber is mainly folded, and is not further pulverized by collisions with the positioned paddles and impact surfaces.

[0053] Nevertheless, in order to make the folding of graphite particles as effective as possible, it has been found that increasing the height of the paddle 5 is particularly advantageous when carrying out the method of the present invention, as clearly shown in Figure 3 (corresponding to Figure 3B of German Patent Application Publication No. 102020100907). As a result, the impact surface is increased when comparing the separator mill and the separator mill of German Patent Application Publication No. 102020100907 derived therefrom. Therefore, when each paddle 5 rotates in the separator chamber while being held by the screw 30 and collides with the graphite particles, the surface area available for head-on collision is increased.

[0054] Ideally, the height of the paddle is between 10 mm and 100 mm in the case of a separator mill and the separator mill described in German Patent Application Publication No. 102020100907, depending on the type, and is increased to 75% to 110% in the case of a spheroidal separator according to the present invention.

[0055] In this case, preferably, more than 45% of the paddle height is located at the height of the vertical gap in the separator wheel from which the fine material is released, when viewed radially.

[0056] The height of the impact surface 6 can be adjusted as needed.

[0057] The enlarged paddle surface allows more graphite particles to be impacted per unit time, causing them to become slightly rounded again. Therefore, more energy can be added per unit time without making individual impacts stronger or causing unnecessary breakage. This allows for faster rounding. In batch processing, the processing time per batch is reduced.

[0058] Furthermore, it has been proven to be advantageous to omit the covering 18, which is shown in an enlarged view in Figure 3B of German Patent Application Publication No. 102020100907.

[0059] Figure 3 shows a spheroidization method that has been implemented to date using a spheroidization separator known in the German Patent Application Publication No. 102020100907 of this application, and is also a method that has probably already been popularized by Hosokawa Alpine Co., Ltd. in a more or less similar form, as described above (which is the result of in-house testing on this topic).

[0060] Spheroidized graphite (SPG) materials of specific quality grades available on the market are manufactured using separate systems specifically designed for this purpose.

[0061] For example, when manufacturing SPG20 and SPG10 graphite materials, the process is carried out using two systems that are configured and operated completely independently of each other, as shown in Figure 4.

[0062] To manufacture fine-grade SPG10 graphite material, the raw material graphite is processed by a separator mill such as a Netch CSM900. 50 The graphite is pre-ground to 10 μm, which makes the graphite particles small enough so that, with the help of one of the spheroidizing separators 2 described above, a fine-grade SPG10 graphite material can be produced from this graphite by simple folding.

[0063] For this purpose, the pre-ground raw graphite 3 is placed in batches on the spheroidizing separator 2. The raw graphite is rotated in the separator chamber for a predetermined time, set so that any graphite particles remaining in the separator chamber are rounded at the end of the rotation time to meet the quality requirements of SPG10. During rotation, fine material (and therefore particles too small for SPG10) is permanently removed and released via the separator wheel in the manner described above.

[0064] The same process is applied completely independently to a second line where fine-grade SPG20 graphite material is manufactured.

[0065] When using 1.233 kg / h of raw graphite, the yield is 661 kg / h, and therefore the total yield is 46.4%.

[0066] The process according to the present invention differs as shown in Figure 5. JPEG0007894410000001.jpg58116

[0067] In this case, an upstream separator mill, a spheroidizing separator usually directly connected downstream of this separator mill, and a second spheroidizing separator also connected downstream of this spheroidizing separator are used. The two spheroidizing separators are preferably identical or have the same structure, but are operated with different fine indicators (other operating parameters → speed, gas volume; other separator wheels). In principle, the spheroidizing separators have the same structure and are operated identically unless otherwise specified in the following description.

[0068] Ideally, the spheroidal separator having the configuration described in German Patent Application Publication No. 102020100907 would be used in the implementation of the present invention, and therefore would also be used in the illustrated exemplary embodiments. Ideally, these spheroidal separators would be further modified to include at least one of the above-described modifications to German Patent Application Publication No. 102020100907.

[0069] In this case, the raw material graphite is also pre-ground.

[0070] However, in this modification of the present invention, the pre-grinding is performed only to the particle size that the coarsest finest class of finished spherical graphite produced by this system should have, at least substantially. This is because the d in the usable particles 50 The significant decrease in this would not normally occur as part of spheroidization unless damage occurs.

[0071] Therefore, in this case, the first useful product is this d 50If it is spherical graphite, then it is essentially d 50 Pre-grinding is performed to a particle size of 20 μm. For graphite materials of a finer class than those produced by the first spheroidizing separator, pre-grinding is not performed to such a strong degree that they can be directly rounded by only one of the spheroidizing separators used here.

[0072] The separator mill 1 used for this preliminary grinding should ideally be the Netch® CSM900.

[0073] According to the present invention, as described above, a plurality of spheroidizing separators 2a, 2b are arranged downstream of the separator mill 1. The upstream first spheroidizing separator 2a contains the fine class to be produced by this separator 2a (for example, in the case of SPG20, d 50 Pre-ground raw graphite, suitable for raw materials of 20 μm, is preferably supplied in batches.

[0074] In this case as well, the placed raw graphite is rotated within the separator chamber for a predetermined time, and this time is set so that the graphite particles remaining in the separator chamber are rounded at the end of the operating time to meet the desired quality requirements, and thus, in this case, a fine-grade SPG20 graphite material is produced.

[0075] The separator wheel of the first spheroidizing separator may be advantageously configured to have a diameter 15% to 25% smaller than the separator wheel of the second spheroidizing separator, which is otherwise almost (at least substantially) structurally identical.

[0076] Particularly preferable, the first spheroidizing separator (more precisely, its paddle) is operated at a rate that changes during each batch process, or at a rate that starts at 100% of the initial rate at the beginning of a batch process and decreases to 70% to 40% of that rate during the process. This allows, on the one hand, to control the first spheroidizing separator to actually produce the desired fine class of graphite material. Simultaneously or alternatively, this allows the first spheroidizing separator to actually output a type and / or quantity of fine material through the inside of its separator wheel that the second spheroidizing separator can perform some processing on.

[0077] Fine material (i.e., particles too small for SPG20 in this example) is permanently removed during rotation in the manner described above. This fine material mainly consists of particles that were already too small after pre-grinding and particles that were broken and became too small during spheroidization in the first spheroidization separator.

[0078] According to the present invention, the fine material is not discarded but is placed directly or via a silo intermediate storage section into the downstream spheroidizing separator 2b. The spheroidizing separator 2b then applies the placed material again to the aforementioned rounding by folding, resulting in the production of a finer micro-class of graphite material, ideally several levels finer than the previously produced micro-class, in this case, for example, micro-class SPG10 graphite material, ideally at least five levels finer in micrometers. The fine material produced in this case is then removed again via the separator wheel.

[0079] However, the second spheroidizing separator (or its paddle) is preferably operated at 100% speed throughout the entire batch process, in contrast to the first spheroidizing separator. In this case, it may be advantageous to reduce the amount of gas flowing through the second spheroidizing separator by 10% to 40% by volume compared to the amount of gas flowing through the first spheroidizing separator.

[0080] Finally, the graphite material having each desired fineness is removed from the separator space in each spheroidized separator by, for example, the method described in German Patent Application Publication No. 102020100907.

[0081] To precisely control the process, advantageously, only two spheroidized separators are connected in series by the described method. To process a larger mass, usually, a plurality of such systems are connected in parallel in the system according to the present invention.

[0082] The yield is significantly increased. When using 960 kg / h of raw graphite, 435 kg / h of graphite material of fine class SPG20 and 167 kg / h of graphite material of fine class SPG10 can be obtained. This corresponds to 62.8% of the total yield.

[0083] FIG. 6 shows an exemplary second embodiment according to the present invention. Except for the differences specified below, the configuration corresponds to the above-described exemplary first embodiment. Therefore, unless otherwise specifically specified from the following differences, the above description is equally applicable below. JPEG0007894410000002.jpg96166

[0084] The difference in this case is that only pre-crushed coarser raw graphite is applied to the first spheroidized separator 2a. By the first spheroidized separator of this system, a specific finest class d of the coarsest 50 To produce, the d of the pre-crushed raw graphite 50 is preferably set 10% - 30% higher than each fineness class. As in the illustrated exemplary embodiment, when graphite of fine class SPG22 is produced, pre-crushing of d 50 of about 24 μm to about 28 μm is performed. This increases the throughput of pre-crushing and broadens the particle size distribution.

[0085] Next, the first spheroidizing separator is operated to produce a mixture of two fine classes, for example, graphite material of fine classes SPG18 and SPG22, as a product.

[0086] A further special feature in this exemplary embodiment is that the separator wheel of the first spheroidizing separator 2a has a smaller diameter than the separator wheel of the downstream spheroidizing separator 2b. In most cases, the separator wheel of the first spheroidizing separator rotates at a higher speed than the separator wheel of the downstream spheroidizing separator.

[0087] This allows the separator space of the first spheroidizing separator 2a to absorb and round off an enlarged batch (in terms of mass) of pre-pulverized graphite.

[0088] In this exemplary embodiment, it is particularly preferable that the first spheroidizing separator 2a (more precisely, its paddle) be operated at a rate that changes during each batch process, which brings about the advantages described above.

[0089] The modifications described for the separator wheel in the first spheroidizing separator 2a result in a reduction in its separation limit. However, this is not an issue due to the additionally provided separators 4 and 5 (described below). These separators compensate for this "deficiency," which allows for the production of usable graphite materials of different fineness classes, such as powder classes SPG18 and SPG22, by ideally utilizing finely pre-ground and arranged raw graphite in the first spheroidizing separator 2a.

[0090] This product is discharged directly downstream from the first spheroidizing separator 2a. The product is further processed to obtain a useful product or final product. For this purpose, an additional first separator is used. In this case, the separator separates rounded graphite particles, substantially belonging to the finest class SPG18, from the product. Thus, a portion of the useful or final product is the finest class 18 graphite material.

[0091] The coarser remaining graphite material resulting from the separation described above is fed into a separate, further separator. In this way, the graphite material is separated again; that is, it is separated into a batch of graphite material coarse enough to be fed again for pre-grinding, and a second batch of useful or final product that forms the fine-grade SPG22 graphite material.

[0092] The fine material removed through the separator wheel of the first spheroidizing separator 2a is not discarded. Instead, this fine material is processed by the second spheroidizing separator 2b in the manner described above with respect to the exemplary first embodiment, and this fine class is, as described above, often several levels lower than the last manufactured fine class, for example, the graphite material of fine class SPG10 in the illustrated embodiment.

[0093] To precisely control the process, even in the illustrated exemplary embodiment, only two spheroidizing separators are connected in series in the manner described. To handle larger masses, multiple separators are typically connected in parallel in such systems according to the present invention.

[0094] This method also results in a significant increase in yield.

[0095] When using 894 kg / h of raw graphite, 137 kg / h of fine-grain SPG22 graphite material, 228 kg / h of fine-grain SPG18 graphite material, and 167 kg / h of fine-grain SPG10 graphite material can be obtained. This represents 60% of the total yield. [Explanation of Symbols]

[0096] 1 Separator Mill 2. Spheroidizing separator 2a First spheroidizing separator 2b Second spheroidizing separator 3 Pre-ground raw graphite 4. Additional first separator 5. Additional second separator

Claims

1. A method for producing specific different fine classes of graphite particles rounded by an impact effect, using multiple spheroidizing separators connected in series, - Pre-grind or pre-grind the graphite material to be rounded. Next, the first spheroidizing separator produces a first fine class of spheroidized graphite material from the graphite material by folding due to a mechanical impact effect, and releases the first fine class of graphite material as the final product in the above method. - At the same time, separate the graphite material that is too finely ground and therefore cannot be processed into the aforementioned first fine class graphite material. - The graphite material that has been separated because it has been crushed too much is supplied to a second spheroidizing separator, and the second spheroidizing separator can produce graphite material that has been spheroidized into a finer second fine class by folding due to the mechanical impact effect from the separated graphite material, and the graphite material that has been spheroidized into the second fine class is also released as the final product in the above method. Includes, A method characterized in that the speed of the separator wheel of the first spheroidizing separator can be variedly controlled during batch processing, and the speed of the separator wheel of the second spheroidizing separator downstream is kept constant during batch processing.

2. A method according to claim 1 for producing specific different fine classes of graphite particles rounded by an impact effect, characterized in that the intensity of pre-grinding or pre-grinding is set such that more than 50% by weight of the graphite material placed in the first spheroidizing separator is separated through the wheel of the first spheroidizing separator and then placed in a second separator for producing a finer class of graphite material.

3. A method according to claim 1 or 2 for producing specific different fine classes of graphite particles rounded by an impact effect, wherein the first spheroidizing separator and the second spheroidizing separator are connected in series, and each of the first spheroidizing separator and the second spheroidizing separator produces the final product.

4. A method according to claim 1 or 2 for producing specific different fine classes of graphite particles rounded by an impact effect, characterized in that the fine material separated by the first spheroidizing separator is placed in the second spheroidizing separator without further separation and / or filtration outside the first spheroidizing separator.

5. A method according to claim 1 or 2 for producing specific different micro-classes of graphite particles rounded by an impact effect, characterized in that the product produced by the rounding of the second spheroidizing separator is several micro-classes finer than the graphite material of the product produced by the rounding of the first spheroidizing separator.

6. A method according to claim 1 or 2 for producing specific different fine classes of graphite particles rounded by an impact effect, characterized in that the diameter of the separator wheel in the first spheroidizing separator is smaller than the diameter of the separator wheel in the second spheroidizing separator, and / or the separator wheel in the first spheroidizing separator rotates faster than the separator wheel in the second spheroidizing separator.

7. A method according to claim 1 or 2 for producing specific different fine classes of graphite particles rounded by an impact effect, characterized in that the first spheroidizing separator is applied to the pre-pulverized raw graphite, and the d50 of the pre-pulverized raw graphite is set to be 10% to 30% greater than the d50 of the coarsest fine class that the first spheroidizing separator is to produce as a product.

8. A method according to claim 1 or 2 for producing specific different micro-classes of graphite particles rounded by an impact effect, characterized in that the first spheroidizing separator is operated such that the graphite material is divided into different micro-classes.

9. A method according to claim 1 or 2 for producing specific different fine classes of graphite particles rounded by an impact effect, characterized in that the first spheroidizing separator is operated in addition to the fine class of graphite material to be produced so that the product also contains graphite particles, the graphite particles are separated via an additional separator and then subjected to further pre-grinding for further grinding and rearrangement into the first spheroidizing separator.

10. A method according to claim 1 or 2 for producing specific different fine classes of graphite particles rounded by an impact effect, wherein the speed of the separator wheel of the first spheroidizing separator can be variably controlled during batch processing.

11. A method according to claim 1 or 2 for producing specific different fine classes of graphite particles rounded by an impact effect, characterized by using two spheroidizing separators and expanding the paddle surfaces of the spheroidizing separators such that the quotient between the net volume of the separator chamber and the paddle surfaces is in the range of 0.5 to 2.

0.

12. A method according to claim 1 or 2 for producing specific different fine classes of graphite particles rounded by an impact effect, characterized in that the quotient between the net volume in the separator chamber and the envelope volume of the separator wheel is between 4.2 and 6.5.

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