Method for operating a roller press for compacting or briquetting material

Abstract

Method for operating a roller press (1) for compacting or briquetting material, wherein the roller press (1) has two counter-rotating press rollers (2) between which a roller gap (W) is formed and at least one of the roller surfaces is provided with a profile, wherein the material (M) in the roller gap (W) between the roller surfaces is pressed into a briquette (3) or into briquettes or a briquette strand, wherein the rollers (2) are preferably cooled during operation, characterized in that that during operation at least one characteristic parameter is continuously determined which depends on the formation of deposits (7) of the material (M) on the profiled roller surface or on the profiled roller surfaces and that one or more operating parameters of the press are changed depending on at least one determined characteristic value in order to reduce caking (7), that the operating parameter(s) are changed by means of a control system in such a way that a deviation of a determined actual value (I) of the characteristic parameter(s) from a target value (S) of the characteristic parameter(s) is minimized, where the press (1) is operated with a variable pressure (P) as an operating parameter and the pressure (P) is changed by a control system depending on the determined characteristic value. and / or the press (1) with variable cooling and / or variable temperature (T) and / or variable feed temperature (T) A ) is operated as an operating parameter and the cooling and / or the temperature (T) and / or the input temperature (T) A) is changed by a control system depending on the determined parameter and / or the press (1) is operated with a variable feed of the input material, namely with a variable quantity flow or mass flow of the supplied input material as an operating parameter, and the supplied quantity of material or the quantity flow or mass flow (m) of the supplied input material is changed by a control system depending on the determined characteristic value and / or the press (1) is operated with a variable rotational speed as an operating parameter and the rotational speed is changed by a control system depending on the determined characteristic value, and whereby A vibration value is determined as a characteristic value by a measurement using a vibration sensor (8). or A fluctuation value is used as a characteristic value, which is determined from fluctuations of a machine parameter, wherein the fluctuation value is determined from fluctuations in the gap width of the roller gap or from fluctuations in the contact pressure of one or both press rollers or from fluctuations in the motor current or motor torque of one or both drives of the press rollers.

Description

[0001] The invention relates to a method for operating a roller press for compacting or briquetting material, wherein the roller press has two counter-rotating (e.g., rotationally driven) press rollers (i.e., compacting rollers or briquetting rollers) between which a roller gap is formed, wherein the roller surface(s) of one or both press roller(s) is / are provided with a profile (e.g., ribbing or briquette troughs), and wherein the material in the roller gap between the (profiled) roller surfaces is compressed into a briquette or briquette strand. Preferably, the roller surfaces are cooled (during operation) and consequently tempered by cooling.

[0002] Furthermore, the invention relates to a roller press that is operated using such a method and that is designed either as a compacting press for compacting material or as a briquetting press for briquetting material.

[0003] The roller press, which is either a briquetting press or a compacting press, is designed as a high-pressure roller press in which the material, e.g., granular or bulk material, is compacted in the roller gap under high pressure. In a compacting press, the material in the roller gap is compacted into a continuous strand of material, which is called a briquette. In a briquetting press, the material in the roller gap is compacted into briquettes or a briquette strand consisting of a multitude of briquettes by the briquetting tools (with briquette troughs) arranged on the roller surfaces. In both cases, at least one of the press rollers can be set against the other press roller by means of force generation, e.g., hydraulically. The press rollers can be, for example,each having a roller core (with a shaft) and a bandage arranged on the roller core or tool segments arranged on the roller core, wherein the bandage or the segments are provided with the roller surfaces and consequently form the roller surfaces.

[0004] In this embodiment, the roller press is used as a compaction press, for example, for the production of fertilizer granules through a process called press granulation or compaction granulation. The starting material (e.g., inorganic substances) is compressed under high pressure in the high-pressure roller press, thereby compacting it to form a strand of material, known as a slurry. This process step is called press agglomeration. This is typically followed in a further step (using a separate system component, e.g., a crusher and / or a mill) by granulation through comminution of the slurry and then preferably by classification.

[0005] In a briquetting press, the roller surfaces are typically formed by a band or segments equipped with briquette troughs, so that the raw material in the roller gap is compressed into the aforementioned briquettes or a briquette strand. In a subsequent process step, the briquette strand can be separated into individual briquettes. Briquetting is used, for example, in the production of HBI (Hot Briquetted Iron) by directly compressing reduced iron into briquettes.

[0006] During operation, compaction presses, for example, tend to cause material to stick to the profiled roller surfaces when compacting inorganic substances for fertilizer production. This sticking is also known as melting. The tendency to melt depends on the temperature of the roller surfaces, which is strongly influenced by the feed temperature and consequently by the temperature of the hot feed material. The tendency to melt can also be indirectly influenced by the ambient temperature, since at higher ambient temperatures the temperature of the feed material generally increases due to reduced heat loss. With higher feed temperatures, the tendency to melt increases. For this reason, the rollers of compaction presses, for example, are cooled during operation, e.g., by internal cooling, which also cools the roller surfaces, in order to counteract the tendency to melt.The same applies to briquetting.

[0007] For example, German patent DE 10 2012 106 527 A1 describes a press roller for a roller press with a roller core and a coolable bandage attached to the roller core. The bandage contains several axially parallel cooling channels distributed around its circumference below its surface, which are connected to an axial central channel in the roller core via radially extending inlet and outlet channels. Distribution from the central channel to the cooling channels in the bandage is effected by distribution rings attached to the end face of the bandage.

[0008] The production of fertilizer granules using a roller press and a downstream two-roll mill is described, for example, in DE 10 2020 131 638 A1. The main focus of this prior art is the cooling of the grinding rollers of the two-roll mill, which is downstream of the high-pressure roller press and serves to crush the fertilizer residue.

[0009] Methods for monitoring the operation of a high-pressure roller press are known from DE 10 2020 114 815 A1 and DE 10 2020 114 835 A1.

[0010] Monitoring the operation of roller presses is particularly common for those roller presses used not for compacting or briquetting material, but for comminution, and which are also known as high-bed roller mills. The primary focus is on monitoring wear or damage to the roller surfaces. Examples can be found in WO 2023 / 104294 A1, WO 2022 / 023869 A1, WO 2014 / 068453 A1, WO 200809016 A1, and DE 21 2021 000 130 U1.

[0011] German patent application DE 20 2015 106 156 U1 describes a roller mill with a sensor unit that measures the distance to a grinding surface during operation to monitor wear. An evaluation unit takes a determined wear parameter into account when controlling the drives. This allows the drive control of the two rollers to be adjusted so that roller wear can be influenced according to a defined criterion. For example, in cases of greater wear, the respective roller is subjected to a lower torque to equalize the cumulative wear of both rollers.

[0012] WO 2007 / 025395 A1 describes a method for monitoring the operating condition of rotating rollers in an industrial plant, whereby vibrations during the operation of a roller are detected and, based on this, measures can be taken during operation, e.g., the emission of a visual or audible alarm signal or even the shutdown of at least part of the plant. The primary applications are roller mills for grain processing or rolling mills for processing suspensions such as chocolate or paints.

[0013] German patent DE 19 731 975 A1 describes a method for preventing the adhesion of material to be briquetted to the surface of a briquetting roller. To prevent caking and sintering, a lubricant emulsion is sprayed onto the roller surface. Metering the lubricant allows the lubricant requirement to be adjusted to the respective roller speed. Furthermore, the metering can be automatically adjusted.

[0014] WO 2018 / 036978 A1 discloses a self-optimizing, adaptive product processing plant and a corresponding method for the milling and / or grinding of grains. The milling and / or grinding takes place in a roller mill with a pair of rollers. Temperature sensors are provided to measure the surface temperature of the rollers. The measured temperature values ​​are used for the optimal adjustment and signal generation of the roller settings.

[0015] Furthermore, a roller system with several rollers and a wetting device is known from DE 10 2020 130 265 A1, wherein a liquid is applied to at least one roller by means of the wetting device. This is intended to prevent the material from adhering to the roller.

[0016] Finally, JP 2017-30034 A deals with the cooling of rollers of a roller press in the course of coal processing.

[0017] Based on the prior art, the invention aims to provide a method for optimizing the operation of a roller press for compacting or briquetting material and consequently the operation of a compacting press or briquetting presses.

[0018] To solve this problem, the invention teaches a method with the features of claim 1. In a generic method of the type described above, it is provided that during operation at least one characteristic parameter is determined continuously (i.e., at intervals or continuously) which depends on the formation of material deposits on the profiled roller surfaces and that one or more operating parameters of the press are changed depending on the determined characteristic value (or values) in order to reduce build-up on the roller surfaces.

[0019] The invention is based on the understanding that build-up on the rollers of a compacting or briquetting press, and consequently the tendency for melting, negatively impacts operation, as increasing build-up reduces the productivity of the presses. For example, during compaction, build-up can lead to a reduction in briquette thickness and thus to a reduction in productivity. The reduction in briquette thickness also leads to an increase in the unwanted residue, which in turn reduces the productivity of the press and generally has a negative impact on the formation of build-up. On the other hand, the formation of build-up also depends on the surface finish of the rollers, as, for example, increasing surface roughness can lead to an increase in build-up.The increase in adhesion can in turn lead to corrosion of the surfaces, resulting in an increase in roughness, which in turn negatively affects the tendency for adhesion in the manner described.

[0020] Based on this understanding, the inventive method reduces and minimizes adhesion by continuously monitoring the formation of adhesions and, consequently, caking during operation. This is achieved by continuously determining a parameter that depends on the formation of material deposits on the profiled roller surfaces. Such a parameter can be determined, for example, by direct measurement with a measuring device, such as a sensor. In one embodiment of the invention, this can be a vibration sensor, so that a vibration value of the roller press is determined as the parameter. The invention recognizes that the vibrations of a roller press are sensitive to the degree of caking and, consequently, to the tendency to melt, so that melting can be detected very effectively by monitoring vibrations.Alternatively, the characteristic value can be determined as a fluctuation value of a machine parameter, e.g., the width of the roll gap, the contact pressure of one or both press rolls, and / or the motor current or torque of one or both press roll drives. For this purpose, one or more measuring devices with, for example, one or more sensors can be provided. The sensor(s) measure, for example, the width of the roll gap, the contact pressure, and / or the motor current or torque. From the measured values, a fluctuation value is determined by the measuring device (or an evaluation device, which can also be part of the measuring device), which is a measure of the fluctuations of the respective machine parameter. This fluctuation value can be used within the scope of the invention as a measure of the build-up.

[0021] Of particular importance is that the inventive method specifically addresses the formation of deposits by modifying one or more operating parameters of the press depending on the determined characteristic value and consequently on the extent of the deposits, in such a way as to reduce the deposits. According to the invention, the tendency to melt is thus specifically counteracted by a predetermined control or regulation of the system. The roller press is therefore operated according to the invention in such a way that the deposits forming during operation are removed again by suitable variation of the press's operating parameters; that is, the press is run free of deposits during operation.

[0022] As an operating parameter that is varied to remove build-up and consequently counteract the tendency to melt, the pressure of the roller press, and thus the pressing pressure, can be used, for example. This means that the pressing pressure is changed during operation depending on the determined characteristic value, e.g., depending on vibrations or fluctuations of a machine parameter of the press. The invention is based on the understanding that the build-up that occurs during operation can be removed again if the initially set pressing pressure is reduced by a certain amount (e.g., temporarily). By reducing the pressing pressure, build-up can be reduced and, if necessary, removed. If, within the framework of the inventive method, it is then determined by monitoring the characteristic value that the build-up has been reduced, the pressing pressure can subsequently be increased again, e.g.,to a predefined normal value. The onset of surface growth, which can be caused, for example, by high temperatures of the feed material, is thus detected, and in one embodiment, the pressure is adjusted accordingly. This reduces the energy input and normalizes the roller surface. If the characteristic parameter(s) improve, the pressure can then be increased again, for example, to the original value.

[0023] Alternatively or additionally, build-up can be counteracted by changing the cooling and / or temperature; that is, the cooling and / or temperature of the rollers, e.g., a surface temperature, is used as a variable operating parameter. Preferably, the rollers of the roller press are each equipped with cooling. This can be internal cooling via, for example, the shaft or the roller core, e.g., via a core bore. By cooling the roller body itself, the surfaces of the roller and consequently the profiled roller surfaces can also be cooled. Alternatively or additionally to internal cooling via the core, the drum or the segments can be cooled, e.g., via cooling channels. By changing the cooling, the surface temperatures of the roller surfaces can be changed, so that either the cooling itself or the resulting surface temperature can be used as an operating parameter. For example, if...If melting or caking is detected in a process with specific parameters, such as a certain pressing pressure and temperature, this caking can be counteracted by reducing the temperature and, for example, by increasing cooling. If this reduces the caking, the cooling can then be reduced again, thus increasing the temperature.

[0024] Alternatively or additionally, the feed temperature of the material onto the roller gap can also be changed as an operating parameter; i.e., by reducing the feed temperature, build-up can be reduced, whereby the feed temperature can then be increased again if necessary after the build-up has been reduced.

[0025] Alternatively or additionally, the roller speed can also be used as a variable operating parameter; that is, the roller speed can be changed to reduce build-up. For example, if build-up is detected during operation, the roller speed can be reduced. Due to the reduced throughput, this leads to improved cooling and thus to a reduction in build-up, so that the tendency to melt can also be counteracted by varying the speed.

[0026] Alternatively or additionally, the amount of material fed can also be changed as a variable operating parameter. This means that to reduce build-up, the amount of material fed to the roller press, or the flow rate or mass flow, can be adjusted. If, for example, build-up is detected during operation, the amount of material fed (e.g., the flow rate or mass flow) can be reduced by adjusting the corresponding upstream components, such as screw conveyors, conveyor belts, or throttle valves or openings. Due to the reduced throughput, this leads to improved cooling and thus a reduction in build-up. Therefore, build-up and the tendency to melt can also be counteracted by varying the material feed.

[0027] Furthermore, it is also possible to reduce the proportion of returned material, i.e., the proportion of fines returned, as an operating parameter to reduce caking. This can be achieved, for example, by changing the comminution process, which influences the proportion of returned material.

[0028] Overall, the variable operating parameters of a roller press include, in particular, the pressing pressure, the cooling and / or surface temperature and / or the rotational speed of the rollers and / or the amount of material supplied (or the flow rate or mass flow).

[0029] It can generally be advantageous to prevent or reduce caking by changing only one of the operating parameters, e.g., only the pressure or only the temperature. However, it is also optionally within the scope of the invention to change several operating parameters to counteract caking.

[0030] The operating procedure for reducing build-up is implemented using a control system. The operating parameter(s) are modified by means of a control system in such a way that the deviation of a measured actual value of the characteristic parameter from a target value of the characteristic parameter is reduced, and in particular minimized. For example, this could involve a control system with variable pressing pressure, i.e., the pressing pressure is changed in a closed control loop in such a way that the deviation of the actual value of the characteristic parameter, e.g., vibrations or fluctuations, from a predetermined target value is minimized.

[0031] It can be advantageous to define specific limits for the operating parameter setting during the control process, so that, for example, arbitrarily low pressing pressures are not set to reduce build-up. Consequently, changes to the operating parameter(s), e.g., during the control process, can be made with the stipulation that one or more predefined maximum or minimum values ​​of the operating parameter(s) are not exceeded or fallen below.

[0032] Therefore, limit values ​​are preferably defined in the control system. It is always advantageous to perform a setpoint / actual value comparison within the framework of the control system. The actual values ​​can be recorded as already described, for example, by measurements with one or more measuring devices. This can involve the direct measurement of a characteristic parameter, e.g., using a sensor such as a vibration sensor, pressure sensor, or position sensor.

[0033] The tendency to melt, which the invention aims to counteract, is related in practice, among other things, to the fact that the feed material is usually warm or hot. For example, when compacting inorganic material to produce fertilizer granules, a specific temperature is generally required to achieve high-quality compaction. For this reason, arbitrarily strong cooling cannot be implemented, as this would impede compaction.

[0034] Overall, the modification of the operating parameters according to the invention should be carried out with the proviso that the quality of the produced briquettes or briquette strand is not impaired or does not fall below their quality requirements.

[0035] Furthermore, the control strategy can be variably adapted to the specific circumstances, e.g., the type of feed material or its mixing ratio and / or the ambient temperature of the press, e.g., outside and / or inside temperatures. For example, a "day mode" and a "night mode" and / or a "summer mode" and a "winter mode" can be provided and implemented in the control system.

[0036] The process is particularly preferably carried out using a roller press for compacting material, and consequently with a compacting press. This can involve, for example, the compaction of inorganic material, especially for the production of fertilizer granules, wherein at least one roller surface is provided with a profile (e.g., a ribbing) for generating a slurry.

[0037] Alternatively, the process can be carried out with a roller press designed as a briquetting press, which is intended, for example, for the briquetting of directly reduced iron and consequently for the production of briquettes (hot briquetted iron), wherein the roller surfaces of a briquetting press are provided with briquetting tools, i.e., with briquette troughs, which form the profiled roller surface.

[0038] The invention relates not only to the described method, but also to a roller press of the described type, which has two counter-rotating press rollers between which a roller gap is formed and whose at least one roller surface (or both roller surfaces) is / are provided with a profile. It can be a roller press used as a compacting press or briquetting press. The roller press according to the invention is equipped with a control unit (as a regulating device) configured to carry out the described method. This control unit is implemented as a regulating device with a control algorithm of the described type. Furthermore, the roller press preferably has at least one measuring device with which the at least one parameter that influences the control process can be determined directly or indirectly.Reference is made to the explanations relating to the claimed method, which also apply to the claimed roller press.

[0039] The invention will now be explained in more detail with reference to the drawings, which merely illustrate exemplary embodiments. They show Fig. 1. Schematically simplified diagram of a plant for the production of fertilizer granules with a roller press, Fig. 2 schematically simplified, a roller press with a control and / or regulating device for carrying out the method according to the invention and Fig. 3 a process diagram relating to an embodiment of the method according to the invention.

[0040] In Fig. Figure 1 is a highly simplified schematic representation of a plant for the production of granules, e.g., for the production of fertilizer granules. The plant comprises a roller press 1 (as a compacting press) with two counter-rotating press rollers 2, between which a roller gap W is formed. The starting material M, e.g., inorganic substances for the production of fertilizer, is fed onto the roller press 1 and compacted in the roller gap W between the press rollers 2 into a strand of material, the so-called slurry 3. The slurry 3 is then reduced to granules 5 in one or more comminution units, e.g., roller mills 4. The material exiting the mills 4 is classified in a classifying device 6, e.g., a screening device, and the end product EP is discharged, while fines R are recycled and fed back into the roller press 1. The present invention relates to the operation of the components within the plant as described in Figure 1. Fig. 1 planned roller press 1.

[0041] This roller press 1, which in the exemplary embodiment is designed as a compacting press and can alternatively also be designed as a briquetting press, is simplified in Fig. Figure 2 shows the compaction press 1. It features the aforementioned counter-rotating press rollers 2, between which a roller gap W is formed. The roller surfaces of one or both press rollers 2 are profiled. In the case of a compaction press, this is, for example, a corrugation. The starting material M is drawn into the gap W between the two press rollers 2 and compacted there to form the aforementioned compaction 3. The press rollers 2 are each cooled and therefore equipped with a cooling device (not shown), which serves in particular to cool the roller surfaces. This is because the starting material M is usually fed onto the roller press 1 in a hot state at high temperatures. Due to the high temperatures, the material M tends to adhere to the profiled surfaces and consequently melt onto them. These adhesions 7 are simplified in the process diagram according to [reference missing]. Fig. 3 indicated.

[0042] This tendency to melt is counteracted according to the invention. For this purpose, at least one characteristic value is continuously determined during operation, which depends on the formation of deposits 7 of material M on the profiled roller surfaces. This characteristic value can be, for example, a fluctuation value determined by measuring fluctuations of a machine parameter, e.g., fluctuations in the roller gap width, using a sensor 8. The roller gap width W and, consequently, a fluctuation value can be determined using the sensor 8. By monitoring this fluctuation value, the formation of melts can be detected and addressed. According to the invention, one or more operating parameters of the press are changed depending on the determined characteristic value, e.g., depending on the fluctuation value determined by the sensor 8, thereby reducing or removing deposits 7.

[0043] In the illustrated embodiment, the pressure, and consequently the pressing pressure P, can be adjusted as an operating parameter, depending on the determined characteristic value and consequently on the detected fluctuations. This is in Fig. 3. After the formation of deposits 7 on the surface begins (process step A), these deposits 7 are detected directly or indirectly by sensor 8 (process step B), and the pressing pressure P is adjusted accordingly (process step C). This results in a reduction of the energy input and thus a normalization of the roller surface (process step D). This is again detected by sensor 8, as the characteristic value and consequently the sensor's measurement signal changes (process step E). The control unit 9 then reacts by increasing the operating parameter, namely the pressing pressure P, again (process step F).

[0044] Fig. Figure 3 therefore shows a control strategy for dealing with build-up on the rollers of a compacting press or briquetting press. The operating parameter(s) (e.g., the pressing pressure P) are modified by means of a control system in such a way that the deviation of an actual value of a characteristic value from the target value of the characteristic value is reduced. The aforementioned pressing pressure P is a suitable operating parameter. Alternatively or additionally, the variable cooling or a variable temperature T of the press rollers 2 can also be used as an operating parameter. This allows the cooling to be adjusted in response to the deviation of the actual value from the target value of the characteristic value, thereby changing and, in particular, reducing the surface temperature of the rollers. By reducing the surface temperature, build-up is counteracted and the roller surface is cleaned. As soon as this is detected, the temperature can be increased again.Alternatively, the input temperature T can also be used as an operating parameter. A The material M fed into the roll gap can be used as an operating parameter. Furthermore, the rotational speed n of the press rolls can be used. Alternatively or additionally, the mass flow rate m of the supplied input material can be used as an operating parameter by adjusting the feed devices upstream of the roll gap (e.g., screw conveyors or belts, throttle valves or openings). Alternatively or additionally, the return material fraction R, and consequently the percentage of returned material, can also be used as an operating parameter.

[0045] The in Fig. The control strategy shown in 3 can be compared with the one in Fig. 2. Implement the roller press shown. In Fig.Figure 2 shows a detection device, e.g., a sensor 8 for vibration detection, next to the roller press 1 with its two press rollers 2. The sensor can detect an actual value I (e.g., for the fluctuation value). This is connected to a control unit 9 (or a controller of a control unit), which is supplied with a setpoint S for, e.g., the fluctuation value and consequently the characteristic value. The control unit 9 or the controller detects a deviation between the setpoint S and the actual value I and reacts by changing the operating parameter, e.g., the pressure P and / or the temperature T and / or the feed temperature T. A and / or rotational speed n and / or mass flow rate m of the supplied input material and / or return material fraction R.

[0046] For example, a press can initially be operated with a surface temperature T of 125 °C and a predetermined pressing pressure P of 180 bar. If build-up is detected, e.g., due to rising temperatures, the pressing pressure can be reduced to, for example, 165 bar, thus cleaning the surface. The pressure P can then be increased back to its initial value.

[0047] It can be advantageous to define specific limits for the setting of the operating parameter (e.g., P and / or T) during the control process, so that, for example, arbitrarily low pressing pressures are not set to reduce build-up. Consequently, changes to the operating parameter P or parameters P and T, e.g., during the control process, can be made with the stipulation that one or more predefined maximum or minimum values ​​of the operating parameter(s) are not exceeded or fallen below. Therefore, limit values ​​are preferably defined in the control system. This applies not only to the operating parameters P and T mentioned as examples but also to the alternative operating parameters T. A , n, m and R or other possible operating parameters. Details are not shown in the figures.

Claims

[1] Method for operating a roller press (1) for compacting or briquetting material, wherein the roller press (1) has two counter-rotating press rollers (2) between which a roller gap (W) is formed and at least one of the roller surfaces is provided with a profile, wherein the material (M) in the roller gap (W) between the roller surfaces is pressed into a briquette (3) or into briquettes or a briquette strand, wherein the rollers (2) are preferably cooled during operation, characterized by , that during operation at least one characteristic parameter is continuously determined which depends on the formation of deposits (7) of the material (M) on the profiled roller surface or on the profiled roller surfaces and that one or more operating parameters of the press are changed depending on at least one determined characteristic value in order to reduce caking (7), that the operating parameter(s) are changed by means of a control system in such a way that a deviation of a determined actual value (I) of the characteristic parameter(s) from a target value (S) of the characteristic parameter(s) is minimized, where the press (1) is operated with a variable pressure (P) as an operating parameter and the pressure (P) is changed by a control system depending on the determined characteristic value. and / or the press (1) with variable cooling and / or variable temperature (T) and / or variable feed temperature (T) A ) is operated as an operating parameter and the cooling and / or the temperature (T) and / or the input temperature (T) A) is changed by a control system depending on the determined parameter and / or the press (1) is operated with a variable feed of the input material, namely with a variable quantity flow or mass flow of the supplied input material as an operating parameter, and the supplied quantity of material or the quantity flow or mass flow (m) of the supplied input material is changed by a control system depending on the determined characteristic value and / or the press (1) is operated with a variable rotational speed as an operating parameter and the rotational speed is changed by a control system depending on the determined characteristic value, and whereby A vibration value is determined as a characteristic value by a measurement using a vibration sensor (8). or A fluctuation value is used as a characteristic value, which is determined from fluctuations of a machine parameter, wherein the fluctuation value is determined from fluctuations in the gap width of the roller gap or from fluctuations in the contact pressure of one or both press rollers or from fluctuations in the motor current or motor torque of one or both drives of the press rollers. [2] Method according to claim 1, characterized by , that one or more operating parameters of the press are changed depending on the at least one determined characteristic parameter in such a way that build-up (7) is reduced by decreasing or increasing the characteristic parameter or parameters by changing the operating parameter(s). [3] Method according to one of claims 1 or 2, characterized by, that the change of the operating parameter(s) during the control is carried out with the proviso that one or more predetermined maximum or minimum values ​​of the operating parameter(s) are not exceeded or fallen below. [4] Method according to any one of claims 1 to 3, characterized by , that measured values ​​are recorded with one or more measuring devices, e.g. with one or more sensors, and a fluctuation value is determined from them. [5] Method according to any one of claims 1 to 4, for compacting inorganic material, in particular for producing fertilizer granules, wherein one or both roller surface(s) is / are provided with a profile for producing a scoop. [6] Method according to any one of claims 1 to 5, for briquetting material, e.g. directly reduced iron, for the production of briquettes (e.g. Hot Briquetted Iron, HBI), wherein the roller surfaces are provided or equipped with briquetting tools having briquette troughs which form the profiled roller surface. [7] Roller press (1) for compacting or briquetting material, with two counter-rotating press rollers (2), between which a roller gap (W) is formed and one or both of whose roller surfaces are provided with a profile, and with a control device (9) for operating the roller press, characterized by , that the control device (9) is configured to carry out the procedure according to one of claims 1 to 6. [8] Roller press according to claim 7, with at least one measuring device for determining the at least one characteristic parameter.

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