INSTALLATION AND PROCESS FOR THE PRODUCTION OF FERTILIZER GRANULES

Abstract

The invention relates to a system for producing fertiliser granules, comprising: - a compacting machine (1) for producing a sheet (S) from inorganic starting material (A); - a breaking device (2) for pre-comminuting the sheet (S) into sheet pieces (P); and - at least two double-roller mills (3a, 3b, 3c) which are arranged one behind the other in the direction of production, wherein the double-roller mills (3a, 3b, 3c) each have two rotationally driven grinding rollers (7), the roller surfaces of which are provided with a profile and between which a roller gap having a gap width is formed, wherein the sheet pieces (P) can be fed successively onto the double-roller mills (3a, 3b, 3c) which are arranged one behind the other in order to be comminuted into granules (E), and wherein the gap widths of the double-roller mills (3a, 3b, 3c) are differently dimensioned or differently adjusted and decrease in the direction of production from double-roller mill to double-roller mill.

Description

1 / 18 “INSTALLATION AND PROCESS FOR THE PRODUCTION OF FERTILIZER GRANULES”

[0001] The invention relates to an installation and a process for producing fertilizer granules from inorganic starting material. The installation has at least one compaction machine in which the inorganic starting material is compacted into a flake, and then a flake is produced from the inorganic starting material. The compaction machine is followed by a crushing device, which is used to pre-fragment the flakes, i.e., the flakes are fragmented or pre-fragmented into flake pieces in the crushing device. Then, these pre-fragmented flake pieces are fragmented into granules of the desired size.

[0002] This type of fertilizer granulate production is also known as press granulation or compaction granulation. Preferably, the compaction machine is designed as a roller press or high-pressure roller press, in which the initial material (inorganic substances) is pressed at high pressure and compacted in the process, so as to produce so-called flake (i.e., a strand of flat, compacted material). This stage of the process is known as press agglomeration. The flakes are pre-crushed in a mechanical crusher, and then the granulate with the desired grain size is produced from these flake pieces in other fragmentation units (e.g., in a two-roll mill), usually with the interposition of one or more classifiers.Since inorganic substances are initially available as products with relatively fine particle sizes, which are not suitable in this form for mechanical spreading in areas to be fertilized, fertilizer granules with a defined particle size are produced by the described pressing granulation process, which can be perfectly handled. In general, the goal is to produce fertilizer granules with a grain size of 1 mm to 5 mm. Petition 870250083135, dated 09 / 16 / 2025, page 8 / 113 2 / 18

[0003] The inorganic substances used in the context of the invention for the production of fertilizer granules may be, for example, mineral substances or substances obtained from the evaporation of salt water, such as chlorides or sulfates, in particular potassium sulfate or potassium chloride. Compound fertilizers are also included, for example, NPK fertilizers.

[0004] In the processes and installations described, it is necessary to distinguish between a roller press, on the one hand, and a two-roll mill, on the other. In the roller press, the initial material is compacted into flakes at high pressure and at relatively low peripheral speeds of the rollers. In a later stage of the process, the two-roll mill is used for grinding the flake pieces, which are produced from the flake after compaction, for example, with the use of a roller crusher. In contrast to roller presses, two-roll mills operate at a relatively high peripheral speed and the material is spread freely as a curtain of material in the roller gap. The surfaces of the rollers of two-roll mills are profiled, i.e., the roller surfaces are usually textured. Therefore, it is also necessary to distinguish between the two-roll mill, on the one hand, and the grinding devices, on the other.Unlike a crusher with a large number of crushing elements (e.g., teeth), which act individually or in small numbers on the fed product and fragment it, fragmentation in a two-roll mill occurs between the grinding surfaces, which can certainly be textured, but without a specific effect of individual fragmenting elements on the particles to be fragmented. Therefore, in a crusher, crushing occurs (essentially) through impact and shear stress, and in a mill, (essentially) through compression and shear stress.

[0005] The compaction of inorganic materials in a roller press is known, for example, from documents DE 28 24 827 B2, DE 38 02 173 C1 and DE 17 58 978.

[0006] Document DE 10 2020 131 638 A1 describes an installation and a Petition 870250083135, dated 09 / 16 / 2025, page 9 / 113 3 / 18 process of the type described at the beginning. The flakes are first fragmented into flake pieces in a crusher and / or hammer mill, and then these flake pieces are fed to the two-roll mill, if necessary, with intermediate sizing. The grinding surfaces of the two-roll mill are cooled during operation.

[0007] In practice, when producing granulated fertilizer using a two-roll mill, it is common not to feed the flake pieces coming out of the flake crusher directly to the two-roll mill, but instead, the flake pieces are first fragmented in an additional fragmentation device, for example, in an impact crusher or in an impact mill and / or in a hammer mill. Only the particles coming out of the impact mill or hammer mill are finally sent to the two-roll mill. In known installations, the two-roll mill therefore serves as the last fragmentation unit for the production of the final product with the desired particle size, since the particle size in the two-roll mill can be adjusted very easily by means of the variable width of the slit.

[0008] Furthermore, it is known, from document EP 3 801 909 B1, regarding a mill installation with multiple mills for the industrial production of ground products. In a multi-roller mill, several pairs of rollers can be arranged one below the other and several processing lines can also be carried out in parallel to each other. The focus is on grinding grains.

[0009] Finally, document DE 16 67 147 B1 describes the granulation of fine-grained materials by pressing with roller presses and subsequent fragmentation by means of impact or hammer mills and classification by means of classification equipment.

[0010] Other material fragmentation facilities and processes are known, for example, from documents CN 210058412, DE 69 904 770 and GB 1 050 158 A.

[0011] Based on the previously known state of the art, the invention Petition 870250083135, dated 09 / 16 / 2025, p. 10 / 113 4 / 18 is based on the objective of creating a facility with which high-quality fertilizer granules can be produced economically. A corresponding process must also be specified.

[0012] To achieve this objective, the invention teaches about an installation with the characteristics of patent claim 1 and a process with the characteristics of patent claim 9.

[0013] A plant is proposed for the production of granulated fertilizer with - a compaction machine (e.g., a high-pressure roller press) to generate a flake from initial inorganic material, - a crushing device for pre-fragmenting the flakes into smaller flake pieces, - at least two double-roller mills arranged one behind the other in the direction of production, each of the double-roller mills having two rotatably driven grinding rolls, the roll surfaces of which are profiled and between which a roll gap is formed with a gap width (preferably adjustable), through which the pieces of flakes can be successively fed to the double-roller mills arranged one behind the other for fragmentation into granules, and wherein the widths of the gaps of the double-roller mills have different dimensions or are adjusted differently and decrease from one double-roller mill to the other in the direction of production.

[0014] The installation may have at least one first two-roll mill disposed downstream of the crushing device and a second two-roll mill disposed downstream of the first two-roll mill, and the slit width of the second two-roll mill is dimensioned to be smaller or adjusted to be smaller than the slit width of the first two-roll mill. Petition 870250083135, dated 09 / 16 / 2025, p. 11 / 113 5 / 18

[0015] Alternatively, an installation with, for example, three two-roll mills or at least three two-roll mills may be carried out, with a third two-roll mill being arranged downstream of the second two-roll mill, with the slit width of the third two-roll mill being dimensioned to be smaller or adjusted to be smaller than the slit width of the second two-roll mill. Naturally, it is also possible to carry out embodiments with more than three two-roll mills, for example, with four or more two-roll mills.

[0016] The invention is based on the observation that the use of two-roll mills in the production of fertilizer granules has proven to be excellent, since the design and mode of operation of two-roll mills basically allow the production of high-quality fertilizer granules. However, according to the invention, the two-roll mill is not used only – as is usual in the state of the art – as the last fragmentation unit, so to speak, for the production of the final product, i.e., not only is one two-roll mill used in the last stage of the process, whose slit width is defined according to the dimensions of the final product, but, according to the invention, several two-roll mills, for example, two or three two-roll mills, are connected in series, so that, for example, the first two-roll mill is used as a pre-fragmentation unit for the flake pieces, i.e.The flake pieces exiting the crushing device are not pre-fragmented in other crushing units before reaching the twin-roll mill, but with the help of the twin-roll mills, on the one hand, additional pre-fragmentation of the flake pieces exiting the crushing device occurs, and on the other hand, the final product is produced with the last twin-roll mill arranged in the cascade. It is particularly advantageous that the widths of the slots of the twin-roll mills can be very well adjusted, so that, for example, a first twin-roll mill is made or fitted with a relatively large slot, while the downstream twin-roll mill and possibly the last one is fitted with... Petition 870250083135, dated 09 / 16 / 2025, p. 12 / 113 6 / 18 a (significantly) smaller slot, which is preferably adapted to the dimensions of the final product.

[0017] In principle, it is possible to arrange the two-roller mills in cascade, one directly behind the other, for example, also one directly below the other, so that the material from the first two-roller mill directly reaches the second two-roller mill and, if necessary, a third two-roller mill, so that the final product comes out of the respective last two-roller mill, for example, the second two-roller mill or the third two-roller mill.

[0018] However, in a particularly preferred embodiment, the installation is additionally equipped with classification equipment, for example, screening devices. Thus, the invention optionally proposes that at least one classification device, for example, a screening device, is arranged between the crushing device and the two-roll mill arranged downstream of the crushing device, for example, the first two-roll mill, and / or between two two-roll mills arranged one behind the other, for example, between the first two-roll mill and the second two-roll mill and / or between the second two-roll mill and the third two-roll mill.

[0019] It is particularly advantageous to design the plant as a closed-circuit compaction and granulation plant, in which the two-roll mills and one or more classification devices are arranged so that the flake pieces pass through the two-roll mills and the screening devices successively in a closed circuit. Examples of this closed-circuit compaction and granulation plant are shown and explained in the description of the figures. With the use of screening devices, the two-roll mills with different slit widths can be operated particularly effectively, as the screening devices ensure that the material of the appropriate size is fed to the respective two-roll mill in a targeted manner, so as Petition 870250083135, dated 09 / 16 / 2025, page 13 / 113 7 / 18 that a two-roll mill with a relatively small slot, for example, is not loaded with larger-sized material. The use of screening devices and the implementation of closed-circuit grinding installations are basically known from the state of the art. According to the invention, however, this concept is of particular importance because several two-roll mills are integrated, one behind the other, into the installation, each with a different slot width, so that the proper loading of the two-roll mills is of particular importance.

[0020] It is particularly preferred to implement an installation in which only two-roll mills are arranged downstream of the grinding unit or flake crusher as fragmentation units, i.e., other fragmentation units (e.g., hammer mills, impact mills, or similar) are preferably omitted behind the flake crusher. Instead, the flake pieces exiting the flake crusher are preferably fragmented exclusively with the various two-roll mills arranged one behind the other, so that particularly effective granulation is achieved based on two-roll mills with adjustable slot widths. Reference is also made to the description of the figures.

[0021] The specific design and construction of two-roll mills can generally be based on knowledge acquired from the state of the art. Preferably, two-roll mills are equipped with two counter-rotating grinding rolls, whose surfaces have a corrugation formed by a plurality of indentations and channel-shaped projections that extend across the width of the roll and are oriented, for example, parallel to or at an angle to the geometric axis of the roll, or in a spiral or arched shape. It is possible to supply the two rolls with corrugations designed differently, with a spiral or arched design generally only being provided on one of the rolls.

[0022] The gaps in the rollers of the two-roll mill can be dimensioned with a clearance width in the range of 0.5 mm to 30 mm, for example, Petition 870250083135, dated 09 / 16 / 2025, p. 14 / 113 8 / 18 from 0.5 mm to 15 mm and, in particular, can be specifically adjusted to the desired clearance width, depending on the installation construction.

[0023] Two-roll mills may also be used, whose grinding rolls are equipped with cooling equipment to cool the surfaces of the rolls. For example, two-roll mills, known from document DE 10 2020 131 638 A1, may be used.

[0024] The invention relates not only to the described installation but also to a process for producing fertilizer granules from inorganic starting material, preferably using an installation of the type described. The starting material is compacted in a compaction machine to form a flake, and the flake is pre-fragmented in a crushing device to form flake pieces. The flake pieces are fragmented to form granules in at least two two-roller mills arranged one behind the other, the two-roller mills arranged one behind the other being sized or adjusted with different slit widths, and the slit widths decrease from one two-roller mill to the next, so that the material successively passes through several two-roller mills with decreasing roller slits. The last two-roller mill arranged in the cascade is preferably adjusted to the dimensions of the granules to be produced.In a particularly preferred manner, the fragmentation of the flake pieces exiting the crushing device then occurs exclusively in the various two-roll mills, without the flake pieces being fragmented in other upstream or downstream fragmentation units (such as impact mills, hammer mills, or the like). Consequently, it is preferable to dispense with other fragmentation units other than two-roll mills behind the flake crusher, so that, in a preferred embodiment, the invention exclusively utilizes the advantages of two-roll mills.

[0025] Regardless, however, additional classification equipment may be provided, i.e., between the crushing device and the mill. Petition 870250083135, dated 09 / 16 / 2025, p. 15 / 113 9 / 18 of two rollers arranged downstream of the crushing device and / or between two two-roller mills arranged one behind the other, the flake pieces are preferably classified, for example, with one or more screening devices. The screening devices may be based on known designs from the prior art, for example, screening devices with one screening belt and / or screening devices with two, three or more screening belts, so that classification into two or more fractions can occur in the screening devices.

[0026] The two-roll mills, which are of particular importance in the context of the invention, are preferably operated at peripheral speeds of at least 5 m / s, for example, from 5 to 30 m / s or from 5 to 25 m / s, preferably from 6 to 20 m / s or possibly from 6 to 15 m / s.

[0027] The surfaces of the grinding rolls of the two-roll mill can be cooled during operation. The grinding rolls can have a diameter of 200 mm to 1000 mm, preferably 400 mm to 800 mm, for example, 500 mm to 700 mm.

[0028] Two-roller mills can (in each case) rotate at a speed or speeds of 100 to 3000 rpm, preferably 120 to 1000 rpm, for example, 150 to 800 rpm.

[0029] With a diameter of 200 mm to 1000 mm and a peripheral speed of 5 to 30 m / s, the speed is 100 to 2860 rpm. With a diameter of 200 mm to 1000 mm and a peripheral speed of 6 to 20 m / s, the speed is 110 to 1910 rpm.

[0030] With a diameter of 400 mm to 800 mm and a peripheral speed of 5 to 30 m / s, the speed is 120 to 1400 rpm. With a diameter of 400 mm to 800 mm and a peripheral speed of 6 to 20 m / s, the speed is 140 to 950 rpm.

[0031] With a diameter of 500 mm to 700 mm and a peripheral speed of 5 to 30 m / s, the speed is 140 to 1100 rpm. With a diameter of 500 mm to 700 mm and a peripheral speed of 6 to 20 m / s, the speed is 160 to Petition 870250083135, dated 09 / 16 / 2025, p. 16 / 113 10 / 18 760 rpm.

[0032] It is possible to operate all the two-roll mills within the installation at the same peripheral speed or rotational speed and / or to size them the same. Preferably, however, it is also possible to size the two-roll mill differently and / or operate it differently, for example, at different speeds, within the installation.

[0033] In any case, the two-roll mills carried out in the installation are operated with different slit widths. The slits of the rolls are adjusted to a slit width from 0.5 mm to 30 mm. Therefore, it may be useful to adjust the slit width of the first two-roll mill to a slit between 10 mm and 30 mm and adjust the slit of the second two-roll mill to a slit width from 0.5 mm to 7 mm. If three two-roll mills are carried out one behind the other, a comparable gradation can be obtained. In the case of three two-roll mills arranged one behind the other, it may be useful to adjust the slit of the first two roll mills to from 10 mm to 30 mm and adjust or size the slit of the second two-roll mill to from 5 mm to 15 mm, as well as the slit of the third two-roll mill to from 0.5 to 5 mm.

[0034] The invention also includes embodiments with more than three two-roller mills arranged one behind the other, for example, with four or more two-roller mills. Even so, a suitable gradation of the roller gap is adjusted.

[0035] Two-roller mills are therefore of particular importance in the context of the invention, namely in combination with a compaction machine, which is preferably designed as a roller press. Therefore, the roller press must be distinguished from a two-roller mill. A roller press for agglomerating fertilizers by pressing has two counter-rotating and driven pressing rollers or compaction rollers that form a roller groove, through which the initial material is pressed into the roller press at high pressure and compacted in the process, so as to Petition 870250083135, dated 09 / 16 / 2025, p. 17 / 113 11 / 18 forming the flakes. Preferably, the roller press is operated with a pressing force of 40 kN to 100 kN per centimeter of roller width. The peripheral speed of the roller press rollers is generally 0.3 to 1.8 m / s and the roller diameter can be 0.5 to 1.5 m, for example. The width of the press rollers is selected according to the desired diameter and productivity.

[0036] The invention is explained in more detail below with reference to the drawings, which merely represent exemplary embodiments without limiting the scope of protection. The following are shown In Figure 1, schematically simplified, an installation according to the invention for the production of fertilizer granules in a first embodiment, In Figure 2, a second embodiment of the invention, In Figure 3, a third embodiment of the invention and Figure 4 exemplifies a two-roller mill that can be used in an installation according to the invention.

[0037] The figures show, respectively, different embodiments of an installation for the production of granulated fertilizer. The installation has a compaction machine 1 to generate a flake from inorganic starting material. The compaction machine is preferably a high-pressure roller press 1, with which the inorganic starting material A is compacted into a flake S, i.e., into a flat strand of material that comes out of the roller slot of the roller press 1. A crushing device 2 is arranged downstream of the roller press 1, with which the flakes S that come out of the roller press 1 are pre-fragmented into pieces of flakes P and, consequently, into granulated material with relatively large and non-uniform dimensions. This crushing device 2, also known as a flake crusher, is equipped with a large number of crushing elements, for example, teeth, which act individually or in smaller numbers on the feed product and fragment it. Petition 870250083135, dated 09 / 16 / 2025, p. 18 / 113 12 / 18

[0038] In all embodiments, several two-roll mills 3a, 3b, 3c are arranged, respectively, downstream of the flake crusher 2, so that the granulated material P passes successively through several two-roll mills after exiting the flake crusher. This applies to all embodiments shown in Figures 1, 2 and 3.

[0039] The basic structure of a two-roll mill 3a, 3b, 3c is shown in Figure 4. The two-roll mill 3a, 3b, 3c has two counter-rotating grinding rolls 7, whose roll surfaces are profiled, for example, as corrugations with a large number of recesses and channel-shaped projections. These recesses and channel-shaped projections (not shown) extend across the entire width of the roll and are oriented, for example, obliquely with respect to the geometric axis of the roll. Each of the rolls 7 may consist, respectively, of a rotatably driven roll core and an annular drum mounted on the roll core, which, in turn, is profiled. The rolls 7 may be equipped, respectively, with a cooling device with which the roll surfaces can be cooled. The specific details are not shown in Figure 4. In Figure 4, however, it is possible to see that the two-roll mills are equipped with a housing 8 that forms an enclosure.In addition, a feed chute 9 is provided through which the material is fed, and this chute 9 may be part of the housing 8 or the casing. In contrast to feeding into a high-pressure roller press, the material is spread freely in the roller slot, like a curtain of material without pressure. To do this, a vibrating channel 5 or a vibrating platform not shown in Figure 4 may be provided, through which the material reaches the chute above the roller slot and, from there, is fed to the roller slot of the two-roll mill.

[0040] According to the invention, not only is a single two-roll mill of this type used as the final fragmentation unit for the production of the final product in the described facilities, but, in each case, several two-roll mills are provided, through which the material or at least part of the material is processed. Petition 870250083135, dated 09 / 16 / 2025, p. 19 / 113 13 / 18 successively passes through the production process, i.e., the flake pieces P that come out of the flake crusher 2 are successively fed to the two-roll mills 3a, 3b or 3c, arranged one behind the other, the widths of the slots of the two-roll mills in an installation having different dimensions or being adjusted differently and, preferably, decreasing in the direction of production from one two-roll mill to the other. Furthermore, in the embodiments shown according to Figures 1 and 2, various classification equipment 4a, b, c, i.e., screening devices in the exemplary embodiment, are integrated into the installation.The installations shown in Figures 1 and 2 are respectively designed as closed-circuit granulation and compaction installations, i.e., the two-roll mills and the classification equipment 4a, 4b, 4c are arranged and interconnected so that the material successively passes through the two-roll mills 3a, 3b, 3c and the screening equipment 4a, 4b, 4c in a closed circuit, until the finished granulate E exits the last two-roll mill 3b or 3c.

[0041] This will be explained first using the installation shown in Figure 1 as an example.

[0042] The initial inorganic material A arrives at the high-pressure roller press 1, for example, by means of a transport device such as a bucket elevator 6, where it is compacted to form flake S. Then, flake S is fragmented into flake pieces P in the flake crusher 2. In the exemplary embodiment of Figure 1, two two-roller mills 3a, 3b are arranged downstream of the flake crusher 2, which are successively traversed towards a closed-circuit grinding installation. To do this, the flake pieces P – possibly by means of another bucket elevator 10 – arrive at a first screening device 4a, equipped with a screening conveyor. The coarse fraction, i.e., the larger grains, is fed to the first two-roller mill 3a by means of a vibrating channel 5, for example, which is adjusted to a first slit width. The material exiting the Petition 870250083135, dated 09 / 16 / 2025, p. 20 / 113 14 / 18 first two-roller mill 3a is fed back to the first screening device 4a in a closed circuit.

[0043] The smaller grains exiting the first screening device 4a, and then the finer material, reach a second screening device 4b, which, in this exemplary embodiment, has been designed for classification into three fractions. The larger grains from the second screening device 4b are fed by a second vibratory channel 5 to the second two-roll mill 3b, from where they arrive again, via a closed circuit, to the first screening device 4a. The intermediate fraction from the second screening device 4b is discharged as the final product and, consequently, as granules E of the desired size. The initial finer material F and, consequently, smaller grains from the second screening device 4b are returned to the production process, i.e., they are returned to the two-roll press 1 with the initial material A for compaction.

[0044] From Figure 1, it is clear that at least part of the material after the flake crusher 2 is fed to the first two-roll mill 3a by means of the first screening device 4a and that the fragmented material therein then passes through the first screening device 4a and is partially fed to the second two-roll mill 3b by means of the second screening device 4b, so that it passes through both the first screening device 4a and the second screening device 4b and exits the second screening device as an intermediate grain and is available as the final product. Both two-roll mills 3a, 3b are therefore arranged one behind the other in the closed-loop process.However, this does not exclude the possibility of some of the material from flake crusher 2, i.e., sufficiently fine material that has already been produced, passing through the first screening device 4a and being fed directly to the second two-roll mill 3b via the second screening device 4b. There are also material components that come out of flake crusher 2 so fine that they are already screened as final product E no. Petition 870250083135, dated 09 / 16 / 2025, page 21 / 113 15 / 18 according to the screening device or are returned to roller press 1 as return products F. However, this does not change the fact that a significant portion of the material passes through the two double-roller mills 3a, 3b successively, one after the other in a closed circuit.

[0045] It is important to note that, in the embodiment according to Figure 2 - as in the other embodiments - only the two-roll mills 3a, 3b are provided behind the flake crusher 2 as additional fragmentation units, i.e., in the production process - as soon as the flake pieces P are available - other fragmentation units such as two-roll mills are dispensed with. It is also advantageous that the slit widths of the two-roll mills 3a, 3b can be adjusted individually.The slit width of the first two-roll mill 3a, 3b is adjusted to be larger than the slit width of the second two-roll mill 3b, because the first two-roll mill 3a serves for additional pre-fragmentation, i.e., the first two-roll mill 3a's main purpose is to process and pre-fragment relatively large flake pieces, so that material that is still (significantly) larger than the final product exits the first two-roll mill 3a. The slit width of the second two-roll mill 3b is adjusted so that granules of the final product size E exit the two-roll mill 3b, a, i.e., the slit width is adjusted (significantly) smaller than the slit width of the first two-roll mill 3a.The fact that the two-roll mills 3a, 3b and the screening devices 4a, 4b are connected in series ensures that the material suitable for the next two-roll mill is fed in a targeted manner, i.e., it prevents material with very large dimensions from being fed to the second two-roll mill, which has a small slit width. The screening devices 4a, 4b in intermediate connection allow the feed load to be reduced and the material size to be adjusted, so that the individual two-roll mills 3a, 3b can be sized to be relatively small in total. The machines. Petition 870250083135, dated 09 / 16 / 2025, p. 22 / 113 16 / 18 systems work particularly effectively because the differences between the feed size and the discharge size, and therefore the fragmentation rate, are small.

[0046] The same advantages are obtained in the embodiment according to Figure 2, in which three two-roller mills 3a, 3b, 3c are connected in series, namely, a first two-roller mill 3a, a second two-roller mill 3b and a third two-roller mill 3c. In this way, a first screening device 4a, a second screening device 4b and a third screening device 4c are also created. The material successively passes through the screening devices 4a, 4b, 4c and the two-roller mills 3a, 3b, 3c in the manner already described. The final product exits the third screening device 4c as an intermediate fraction and therefore as intermediate grains.With this design of three double-roll mills, the respective slit width of the individual mills can be adapted even more precisely to the material being processed, so that the individual double-roll mills are loaded only with material sizes suitable for particularly effective operation of the respective double-roll mill 3a, 3b, 3c. The screening devices 4a, 4b, 4c in intermediate connection also reduce the feed load and perfectly adapt the feed size so that relatively small machines can be used.

[0047] A modified embodiment of the invention is shown in Figure 3. This installation also has several two-roll mills 3a, 3b, 3c, i.e., three two-roll mills arranged one behind the other in the exemplary embodiment. However, in this simplified embodiment, intermediate screening devices are dispensed with. The material passes from the flake crusher 2 to the first two-roll mill 3a, from there to the second two-roll mill 3b and finally to the third two-roll mill 3c, so that it is possible to obtain a cascade of three two-roll mills arranged one behind the other. The slit widths are graduated so that Petition 870250083135, dated 09 / 16 / 2025, p. 23 / 113 17 / 18 only the material that is smaller than the desired maximum granule size, for example, not larger than 4 mm, exits the third two-roller mill 3c. Since it is unavoidable that the finer material, which cannot be used as granules, also exits the third two-roller mill, a screening device 4a is also connected downstream of the cascade of several two-roller mills in this embodiment, so that only the larger grains are used as granules and, consequently, as the final product E, while the finer material that passes through the screening device 4a is fed back into the process and, consequently, to the roller press 1 with the initial material A. In this embodiment, only two-roller mills 3a, 3b, 3c are also provided as fragmentation units behind the flake crusher 2.

[0048] Figure 3 is characterized by a particularly simple structure, as screening devices between the fragmentation units are dispensed with. However, the embodiments shown in Figures 1 and 2 are characterized by the advantage already described in comparison with the embodiment shown in Figure 3, namely that the feed load to the respective two-roll mill is reduced and the material fed to the respective two-roll mill is well adapted to the respective slit width, so that the machines operate effectively and perfectly and can be appropriately sized to a small size.

[0049] As mentioned, Figure 1 shows an embodiment with two double-roller mills 3a, 3b connected one behind the other, and Figures 2 and 3 show embodiments with three double-roller mills 3a, 3b, 3c connected one behind the other, in each case. The invention also includes embodiments with four or more double-roller mills arranged one behind the other. In this case, it is also advisable to increase the number of screening devices accordingly. In Figure 2, this is indicated schematically, in a simplified way, by the symbols above the third double-roller mill 3c and above the third screening device 4c, as other double-roller mills or Petition 870250083135, dated 09 / 16 / 2025, p. 24 / 113 18 / 18 screening devices can be optionally integrated at the points marked for carrying out configurations with more than three two-roll mills. The same applies to Figure 3, in which the symbol below the third two-roll mill 3c also shows the possibility of optionally integrating a fourth two-roll mill or additional two-roll mills, for example. Petition 870250083135, dated 09 / 16 / 2025, p. 25 / 113

Claims

1 / 5 CLAIMS 1.Installation for the production of fertilizer granules characterized by having - a compaction machine (1) for generating a flake (S) from inorganic starting material (A), - a crushing device (2) for pre-fragmenting the flakes (S) into flake pieces (P), - at least two two-roller mills (3a, 3b, 3c) arranged one behind the other in the direction of production, with each of the two-roller mills (3a, 3b, 3c) having two rotatably driven grinding rolls (7), whose roll surfaces are profiled and between which a roll gap with a gap width is formed, and the flake pieces (P) can be successively fed to the two-roller mills (3a, 3b, 3c) arranged one behind the other for fragmentation into granules (E), and the widths of the gaps of the two-roller mills (3a, 3b, 3c) having different dimensions or being adjusted accordingly. They differ and decrease from one two-roller mill to the other in the direction of production.

2. Installation according to claim 1, characterized in that it has at least one first two-roller mill (3a) disposed downstream of the grinding device (2) and a second two-roller mill (3b) disposed downstream of the first two-roller mill (3a), wherein the width of the slit of the second two-roller mill (3b) is dimensioned to be smaller or adjusted to be smaller than the width of the slit of the first two-roller mill (3a).

3. Installation according to claim 2, characterized in that a third two-roll mill (3c) is disposed downstream of the second two-roll mill (3b), wherein the width of the slot of the third two-roll mill is dimensioned to be smaller or adjusted to be smaller than the width of the slot of the second two-roll mill (3b).

4. Installation according to claim 3, characterized in that a fourth two-roll mill and additional optional two-roll mills are arranged downstream of the third two-roll mill (3c), wherein the width of the slot of the fourth two-roll mill is dimensioned to be smaller or adjusted to be smaller than the width of the slot of the third two-roll mill and so forth.

5. Installation, according to any one of claims 1 to 4, characterized in that at least one classification device (4a, b, c), for example, a screening device, is arranged between the crushing device (2) and the two-roll mill arranged downstream of the crushing device, for example, the first two-roll mill (3a), and / or between two two-roll mills arranged one behind the other, for example, between the first two-roll mill (3a) and the second two-roll mill (3b) and / or between the second two-roll mill (3b) and the third two-roll mill (3c).

6. Installation, according to any one of claims 1 to 5, characterized in that, in this embodiment, it is a closed-circuit granulation and compaction installation, in which the two-roll mills (3a, 3b, 3c) and one or more classification devices (4a, 4b, 4c) are arranged so that the flake pieces (P) pass through the two-roll mills (3a, 3b, 3c) and the screening devices (4a, 4b, 4c) at least partially in a successive manner in a closed circuit.

7. Installation, according to any one of claims 1 to 6, characterized in that the surfaces of the grinding rolls (7) of the two-roll mills (3a, 3b, 3c) have a corrugation formed by a plurality of channel-shaped recesses and projections extending across the width of the roll and, in the case of one or both rolls, are oriented, for example, parallel or obliquely to the geometric axis of the roll or in a spiral or arched shape. Petition 870250083135, dated 16 / 09 / 2025, p. 27 / 113 3 / 5 8. Installation, according to any one of claims 1 to 7, characterized in that the roller slots of the two-roll mills (3a, 3b, 3c) are dimensioned or adjusted, respectively, to a slot width in the range between 0.5 mm and 30 mm.

9. Installation according to claim 8, characterized in that, in an installation with two two-roll mills (3a, 3b), the width of the slit of the first two-roll mill (3a) is adjusted or dimensioned from 10 mm to 30 mm and the width of the slit of the second two-roll mill (3b) is adjusted or dimensioned from 0.5 mm to 7 mm or that, in an installation with three two-roll mills, the width of the slit of the first two-roll mill (3a) is adjusted or dimensioned from 10 mm to 30 mm, the width of the slit of the second two-roll mill (3b) is adjusted or dimensioned from 5 mm to 15 mm and the width of the slit of the third two-roll mill (3c) is adjusted or dimensioned from 0.5 mm to 5 mm.

10. Installation, according to any one of claims 1 to 9, characterized in that the grinding rolls (7) of the two-roll mills (3a, 3b, 3c) or at least one two-roll mill are fitted with a cooling device to cool the surfaces of the rolls.

11. Process for the production of fertilizer granules from inorganic starting material (A) characterized by having an installation as defined in any one of claims 1 to 10, wherein the starting material (A) is compacted in a compaction machine (1) to form a flake (S), wherein the flake (S) is pre-fragmented in a crushing device (2) to form flake pieces (P) and wherein the flake pieces (P) are fragmented into granules (E) in at least two two-roll mills (3a, 3b, 3c) arranged one behind the other, wherein the two-roll mills (3a, 3b, 3c) arranged one behind the other are dimensioned or adjusted with different slot widths and Petition 870250083135, dated 09 / 16 / 2025, p. 28 / 113 4 / 5 slot widths decrease from one two-roll mill to the other.

12. Process according to claim 11, characterized in that the fragmentation of flake pieces (P) occurs exclusively in the various two-roll mills (3a, 3b, 3c) without other fragmentation units upstream or downstream.

13. Process, according to claim 11 or 12, characterized in that the flake pieces are classified between the grinding device and the two-roll mill (3a) arranged downstream of the grinding device (2) and / or between two two-roll mills (3a, 3b, 3c) arranged one behind the other, for example, with one or more screening devices (4a, 4b, 4c).

14. Process according to claim 13, characterized in that the material is circulated, wherein, preferably, the material exiting a two-roller mill (3a, 3b, 3c) is fed to a screening device (4a, b, c).

15. Process, according to any one of claims 11 to 14, characterized in that the surfaces of the grinding rollers (7) are cooled during operation.

16. Process, according to any one of claims 11 to 15, characterized in that the grinding rollers (7) rotate at a peripheral speed or at peripheral speeds of at least 5 m / s, for example, from 5 to 30 m / s, for example, from 5 to 25 m / s, preferably from 6 to 20 m / s.

17. Process, according to any one of claims 11 to 16, characterized in that the grinding rolls (7) have a diameter of 200 mm to 1000 mm, preferably 400 mm to 800 mm, for example, 500 mm to 700 mm, and / or rotate at a speed or speeds of 100 to 3000 rpm, preferably 120 to 1000 rpm, for example, 150 to 800 rpm.

18. Process, according to any one of claims 11 to 17, characterized in that the roller clearance is adjusted to a width of Petition 870250083135, dated 09 / 16 / 2025, p. 29 / 113 5 / 5 clearance of 0.5 mm to 30 mm, wherein, preferably, in an installation with two two-roll mills (3a, 3b), the clearance width of the first two-roll mill (3a) is adjusted to 10 mm to 30 mm and the clearance width of the second two-roll mill (3b) to 0.5 mm to 7 mm or wherein, in an installation with three two-roll mills, the clearance width of the first two-roll mill (3a) is adjusted to 10 mm to 30 mm, the clearance width of the second two-roll mill (3b) to 5 mm to 15 mm and the clearance width of the third two-roll mill (3c) to 0.5 mm to 5 mm. Petition 870250083135, dated 16 / 09 / 2025, p. 30 / 113

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