JP6522731B2 - Methods and devices for pretreatment and separation of materials comprising multi-material based composites - Google Patents

Description

  The present invention relates to a method for the pretreatment and separation of materials comprising composite multi-substance systems, and to a vertical roller mill for carrying out this method.

  In Germany, approximately 80 million tons of construction waste are produced each year. Most of this is crushed concrete (pieces). Concrete, and thus crushed concrete, consists essentially of grit, sand and cement stone. Cement stone, among other things, serves to combine the other two components.

  In particular, it is desirable to pre-treat the crushed concrete so that it can be separated into its individual components in areas where natural grit and sand deposits are not present. Above all, collecting grit and / or sand used here is a matter of interest. However, it is of great importance here that the grit and sand be as completely refined as possible to the cement stone. The reason is that otherwise, when using the recovered grit or sand to produce concrete, the concrete produced in such a manner will sometimes have lower strength .

  WO 2011/142663 A1 discloses, for example, separation devices for comminuting crushed concrete and, if possible, recovering individual components of the concrete . However, with this device it is not possible or only possible to achieve the desired level of purity of the individual recycled components, such as grit and sand, or under particularly favorable conditions. is there.

  An essential feature of concrete recycling is, inter alia, that grit should not be comminuted during the pre-treatment of crushed concrete. The reason is that otherwise it is simply limited to low quality concrete products that can be used further.

  Recently, roller mills, which are practically pure milling units, have also been used to pretreat and separate materials.

  Such a method is known, for example, from WO 2011/107124 A1. In the method described therein, a stainless steel slag composed of a silicate part and a metal part is comminuted in a targeted manner, these parts being thereby separated from one another . Significant hardness differences and density differences between the individual parts are exploited to achieve separation during milling. The essential features of this method are primarily to continue to use the mill as a comminution unit, to clearly comminution of the raw materials supplied, and simply as secondary downstream characteristics , Separation is also realized. In short, if one of the components to be separated through the required pressure-based comminution is ductile, it is such that it is not comminuted during the comminution process. The method makes it possible to realize the separation. In other words, separation takes place in that one component is milled by roller pressure while the other component is not milled. This is possible because the components that are not to be milled have ductile properties. If the pressure during grinding is slightly too high, this component will in fact deform, which is undesirable, but it remains unmilled.

  However, such methods do not have any ductile component, so all components or components of the crushed concrete will be milled by the mill, so such a method Can not be used for pre-treatment and separation of crushed concrete. Thus, the desired result, among other things, the purification and recovery of grit can not be achieved.

International Publication No. 2011/142663 International Publication No. 2011/107124 International Publication No. 2008/090923

  The object of the present invention is to show a method and a device by means of which the pretreatment and separation of materials comprising multi-material based composites is possible, the components of the multi-material system being totally ductile It has no characteristics.

  This object is achieved according to the invention through a method for pretreating and separating materials comprising multi-material based composites having the features of claim 1 and through a vertical roller mill having the features of claim 13. Be done.

  Advantageous embodiments of the invention are indicated in the dependent claims and the description.

  A method according to the invention for pre-treating and separating multi-material-based composites, wherein the multi-material-based composite is connected to at least a first component and to the first component. According to the method according to the invention, the two components having no ductile properties, according to the invention, a roller mill with a grinding pan and a grinding roller for in-bed attrition The material is fed as feed material.

  A grinding bed of treated material and of the material to be treated is formed on the grinding pan during operation, and the grinding roller rolls on the grinding bed. During grinding in the bed, the material is separated into the first and second components by the grinding roller in the grinding bed, through shear stress between themselves of the particles of the component and polishing, of the first component The particles, the particles of the second component, and the particles of the same component are milled together.

In order to promote attrition in the bed in the roller mill, the roller mill operates the rollers with an extremely low pressing force. A contact pressure in the range from 15 kN / m ² up to 140 kN / m ² is thus reached for the projected area in the direction perpendicular to the average roller diameter. Here, the pressing force is essentially selected such that the pressure-based comminution of the first and / or the second component is not carried out directly by the contact pressure. In other words, the pretreatment of the material essentially takes place only through mutual grinding of the material and the particles of the first and / or second component. Pressure based comminution is not provided. As far as milling is carried out, this is mainly achieved through the mutual grinding of the materials.

  Moreover, the roller mill is operated such that the grinding bed has a minimum height which is greater than the diameter of the particles of one of the two components. Following milling in the bed and treatment in the grinding bed, at least first and second components are removed from the processing circuit of the roller mill and sorted.

  A roller mill, in particular a vertical roller mill, is no longer used as a milling unit and the material to be milled is "pushed" through the pressure of the roller, but instead a roller mill, in particular a roller The method according to the invention in that the grinding bed formed on the mill is used for separating and pretreating the feed material into its component parts, in particular into the first and second components. It is possible to see the core concepts. The separation and pretreatment of the feed material takes place in the grinding bed, through mutual friction stress, ie grinding of the material.

  Corresponding to the invention, through the formation of the grinding bed according to the invention with only extremely low compressive stress in the grinding bed through the rollers, the grinding process consists of the individual components of the material constituting the multi-material composite It has been recognized that it takes place or is promoted between

  Thus, it is also possible to separate multi-material systems by means of a roller mill, using the in-bed grinding according to the invention, the components of the multi-material system having no ductile properties at all. It is also possible to carry out such separations using multi-material systems, the components of which are brittle. In other words, the grinding is essentially no longer carried out in the mill. The reason is that, in essence, the pressing force of the roller is dimensioned so that milling is no longer possible, either through the roller or through the direct influence of the roller on the grinding bed. The separation of the components of the multi-material system and the partial comminution associated therewith are mainly realized through the grinding process carried out in the grinding bed.

  Within the scope of the present invention it is to be understood that grinding or grinding is the purification of several components from adhesion between themselves, through rubbing against each other. Is possible. Here, the separation of the components takes place, inter alia, through shear forces on the surface, which are created by the components rubbing against one another, which leads to the purification of the individual components.

  A further core concept that forms the basis for the present invention is that the grinding bed is formed to have a minimum height which is greater than the diameter of the particles of one of the two components. In particular, the harder or tougher of the two components in the multi-material composite is selected. Through this design of the grinding bed it is ensured that the harder components are not milled through the roller pressure. In this context, it does not necessarily have to be the hardest of the components. Also, for example, it is advantageous if the grinding bed height is at least as high as the average size of one of the components. Thus, during the pre-treatment process, there is essentially pre-treatment and comminution due to the attrition process in the comminution bed, and thus no comminution-based grinding, rather than pressure-based comminution That is ensured with sufficient probability.

  According to the meaning of the invention, multi-material composites can also be composed of more than two components which are shown here by way of example. Also, more tacky components can be understood as harder components within the meaning of the present invention.

The pressing force of the preferably selected roller (which may alternatively be described as a grinding roller) is such that the contact pressure is in the range from 15 kN / m ² up to 140 kN / m ² It is selected. The pressing force depends, inter alia, on the size of the roller, the size of the vertical mill and / or the weight of the roller. Here, the contact pressure is used as a reference value, such that a guide variable is present, regardless of the dimensions of the roller or mill. The preferred range of contact pressure depends on the material to be treated, and essentially, the contact pressure is chosen such that there is no pressure-based comminution of the ground material. As many different hardnesses exist throughout the multi-material system when processing natural multi-material systems, small parts that have been subjected to undesirable pressure milling or have been unsuccessfully processed are completely Can not be excluded.

  The invention is further based on the surprising finding that processing of the feed material is possible despite contact pressures which are actually too low for the operation of the roller mill. This is, in essence, in contrast to the previous mode of operation of the mill, the actual comminution no longer takes place, but instead, the materials essentially treat each other with one another and are processed by rollers It is in the point that it is not done. This also leads to the fact that pretreatment and separation of materials whose components essentially do not have any difference in density are possible by the process according to the invention.

Advantageously, the shear forces between the particles themselves which are created between the grinding in the bed is in the range from 5 kN / m ² to 70 kN / m ^2, especially, of between 7 kN / m ² of 20 kN / m ² The pressing force is selected to be in range. The ranges indicated for the shear forces between the particles of the different components of the multi-material composite promote good attrition in the grinding bed, pre-treatment and separation of the multi-material composite , Can be implemented in the mill. Here, too, the shear forces present allow for a sufficiently high purity among the individual components to be realized without the risk of excessive comminution.

  An essential element for adjusting the shear force is the pressing force of the roller. Ideally, this should be set so that the desired shear is produced in the grinding bed by rotating the grinding plate in combination with the rollers and by rotation of the rollers. In other words, different shear or friction forces act on the material to be treated. That is, on the one hand, the shear and friction between the individual material particles themselves and, on the other hand, the shear applied to the material via the rollers.

  Usually, when using a roller mill as a comminution unit, the rollers are set to rotate by the comminution bed. Thus, it can be assumed that under normal conditions, the circumferential speed of the roller is of similar magnitude to the relative speed of the grinding bed positioned above the rotating grinding plate is there. However, if the rollers rotate more slowly than the grinding plate or bed, different speeds at the contact points lead to the generation of shear forces, which are used for grinding in the bed according to the invention It is possible.

  More specifically, the generation of shear is essentially based on the velocity of the particles guided along the lower side of the mill compared to the circumferential velocity of the roller, the roller being swept by the particles ) Or the roller advances the particles.

In contrast to the standard operating mode when grinding with a roller mill, it is necessary to clearly increase the height of the grinding bed by the method according to the invention. For the process according to the invention, the grinding bed preferably has a maximum height of 8% of the diameter of the grinding pan , but preferably has a maximum height of approximately 4% of the diameter of the grinding pan There is. In the conventional mode of operation of the roller mill, the grinding material is actively milled or broken by the roller. Here, the grinding gap, ie the distance between the grinding roller and the grinding plate or grinding pan, so that the force introduced into the grinding bed by the grinding roller can be actively used to grind the grinding material But it is desirable not to be too big. If the grinding gap becomes too large, it may occur that the ground material is only partially compressed and thus that no sufficient pressure is applied to the ground material, on the other hand It can occur that the grinding material flows out of the grinding gap so that the grinding material is displaced but not pulverized.

  In contrast, corresponding to the mode of operation according to the invention, it is desirable that the movement of the particles or components of the multimaterial system be milled so as to occur in the grinding bed. Therefore, it is preferred if the height of the grinding bed is clearly greater than in the case of the roller mill used exclusively for grinding. The height of the larger grinding bed leads to a greater relative movement of the particles or components in the grinding bed among themselves, as this is achieved by the grinding in the bed.

In principle, the height of the grinding bed can be adjusted by the pressing force of the rollers, the feed mass flow, the rotation speed of the grinding pan, the height of the holding rim of the grinding pan and / or the inner circulation flow It is.

An increase in the pressing force of the grinding roller reduces the height of the grinding bed through the associated increase in contact pressure. An increase in feed mass flow, ie, when more ground material per unit time is fed to the roller mill as feed material, increases the height of the grinding bed. And, in contrast, the higher grinding pan rotation speed reduces the height of the grinding bed as the existing grinding material is removed from the grinding pan more quickly again. The holding rim of the grinding pan is located at the edge of the grinding pan and is used to reduce or prevent spillage of grinding material beyond the edge of the pan. If the height of the retaining rim is increased, the height of the grinding bed also increases.

  A further parameter that can be used to adjust the height of the grinding bed is the inner circulation flow rate. Here, it is, inter alia, in the case of a roller mill with integrated classifier, the amount of particles that are eliminated during classification and of the particles that are recycled back to the grinding pan for further processing. It is a matter of quantity. If the inner circulation flow rate is increased, the height of the grinding bed also increases. The inner circulation flow rate can be influenced, for example, by the classifier settings and also by the volume of the process air stream.

For example, if the material binding of a multi-material system is increased, increasing the pressing force to realize the force necessary for grinding in the bed despite the increased material binding. Has proven to be advantageous. However, the height of the grinding bed should ideally be kept constant, so other parameters correspond to this if it is likely that the height of the grinding bed will be reduced through the increase of the pressing force Must. Here, it is preferable to increase the feed mass flow and / or the inner circulation flow. Alternatively or additionally, it is also possible to reduce the speed of rotation of the grinding pan. Also, setting of these parameters is possible during ongoing operation, for example, if during testing it is confirmed that the multi-material system material binding is greater than ever before It is possible to cope with it through the parameters shown in.

  A further possibility is to increase the height of the retaining rim. However, this is not possible during ongoing operation, or simply with difficulty. Thus, this change is mainly used when the roller mill being used is to be switched to or designed for a different multi-material system.

  If the material binding of the multi-material system is reduced, the pressing force is correspondingly reduced, which in principle leads to an increase in the height of the grinding bed. Here, it is possible to adjust the previously mentioned parameters in opposite directions in order to counteract this.

During the operation of the roller mill, it is in principle desirable to process as high throughput as possible, ie as much feed material as possible per unit time. In order to increase the throughput, it is advantageous to increase the rotational speed of the grinding pan, in particular in order to maintain the height of the grinding bed, if the mass flow is increased. Also, an increase in the pressing force of the rollers will in fact reduce the height of the grinding bed, which will lead to a change in the grinding variables in the bed. Among other things, the grinding pressure, ie the force introduced into the grinding bed by the roller, is increased through the higher roller pressing force, which also increases the contact pressure. This can lead to poorer multi-material pre-treatment and separation. Thus, if the feed mass flow rate is increased, it is preferred that this should be compensated only through an increase in the rotational speed of the grinding pan. Also, if the inner circulation flow rate is forced to increase, it is possible to do the same. This is the case, for example, if a higher degree of degradation of the material is required, and thus less material is removed as fines through the classifier. As already indicated above, this leads to more material being fed back to the grinding plate and, in a manner analogous to the case of increased feed mass flow, the height of the grinding bed Lead to an increase in It is also preferred here to control this essentially solely through adaptation, in particular through increasing the rotational speed of the grinding pan, so that the height of the grinding bed remains constant.

  Different roller mill types are known. In some roller mills, the rollers are driven directly. Among other roller mills of the LOESCHE type, the rollers themselves are not driven, but instead are set to rotate through the frictional forces created between the rollers and the grinding bed. This is relatively unproblematic in the normal operating mode of the roller mill, where the roller mill is used for grinding. However, when using a roller mill for in-bed grinding, it is confirmed that more attention should be paid to the rotation of the grinding roller due to the extremely low pressing force of these grinding rollers It was done.

  In this connection, it is preferred if the roller mill is operated during activation by the roller pressing force which is higher than the pressing force selected during operation. This is necessary to initially set to rotate the roller with the starting torque to be overcome. Subsequently, during the grinding operation in the bed, the friction between the grinding bed and the grinding roller is in most cases sufficient to maintain the rotation of the roller.

  In this context, it is preferred that the rotation of the roller be monitored during operation, and if it is determined that the rotation of the roller is too low, then the pressing force of the roller takes at least a long time Preferably it is increased. Inadequate rotation of the roller leads to a change in the shear force introduced by the roller into the grinding bed and thus also the quality of the grinding in the bed. Through the short-term increase of the pressing force of the roller, it is ensured that the roller has sufficient rotation or sufficient angular momentum. In the sense of the invention, an insufficient rotation of the roller is understood to mean that the circumferential speed of the roller is less than 50% of the speed of the material flow under the roller. By approximation, it can be assumed that the material flow under the roller corresponds to the rotational speed of the grinding pan or grinding plate below the roller. Depending on the material, a few percent adaptation may be provided to facilitate better speed estimation.

  Roller bearings are conventionally used to promote the start-up of the roller mill, among other things simply to facilitate setting the rotation of the grinding roller, together with a low acceptable pressing force for attrition in the floor It is also advantageous to be designed with a large play. This, on the one hand, reduces the starting torque and, on the other hand, the risk of stopping, or the grinding roller, which has a too low rotational speed.

  According to a preferred embodiment, the roller mill is operated in overrunning and / or air stream mode. In the mode of operation as a pure overrunning mill, the pretreated grinding material is in particular conveyed through the rotation of the grinding pan, optionally over the holding rim present (overrun), and under the grinding pan. Fall into the area. It can be transported away from here. In the air stream operating mode, the grinding material falling over the grinding plate is taken up by the process air stream and blown up, among other things. Above the grinding pan, in most cases, a classifier is present, and the pretreated grinding material is transported to the classifier by the process air stream. The classification takes place in the classifier, and the finely divided pre-treated ground material is adapted to be discharged from the pre-treatment process, while the ground material which is to be further processed is the so-called exclusion As a product, it is fed back to the pretreatment process.

Also, in connection with the present invention, grinding within the bed is described as the grinding process, among others. The reason is that the milling process of this is the standard milling processes may be considered to be distantly related, through different milling techniques, because different from the standard milling processes. However, the grinding in the bed is carried out by means of a roller mill and thus in the practical sense no further grinding takes place, but the terminology relating to the mill is applied for easier understanding. In the combined overrunning and air stream mode, not all overrunning grinding material is taken up by the process air stream sweeping around the grinding pan, but instead only a fraction of it is taken up. Further proportions drop downward and are transported by transport means away from under the grinding pan.

  According to a preferred embodiment, the material comprising the multi-material based composite material to be pretreated and separated is crushed concrete. The crushed concrete itself is mostly composed of grit, sand and cement stone. The method according to the invention allows the grit and sand to be separated from one another and from the cement stone and to be refined by grinding in the bed. Through grinding in the floor, inter alia, grit and sand are scraped away from the cement stone, and after the process according to the invention grit and sand are once again present in essentially pure form, thus concrete It can be reused for the product.

  In a further advantageous embodiment of the method, a vertical roller mill with a classifier is used, and it is also possible to integrate the classifier. In addition, components such as cement stone and composites from the first and second components such as cement stone and at least partially sand etc. are classified by the process air stream from the overrunning crushed material A process air stream is set up such that the first refined components, such as grit and sand, are removed from the grinding process as coarse-grained material, while being transported to.

  For example, at least some proportions of the finely divided second component, such as finely divided cement stone, etc., are removed from the grinding process as fines in the classifier and there is also a deficiency of the second component Particles of finely ground particles, and adherents of the first and second components (eg cement stone and composites of cement stone and sand, etc.) are excluded by the classifier and fed to the grinding pan It is further provided that it is returned. In addition, it is possible to separate the sand from the coarse-grained material removed by the screen and thus to promote further separation in the case of multi-material systems comprising more than two components.

  According to an advantageous embodiment, the vertical roller mill is operated in a combined mode of overrunning and air stream. The process air stream sweeps from below around the grinding pan, and the process air stream contains only light or small material, in particular cemented cement stone and cement and sand glue, which are classified in the classifier. A process air stream is set to transport in the upward direction. Refined heavy components, such as sand and grit, can be directed downward against the process stream and can be discharged from the grinding process as coarse-grained material. In addition, component adherents such as grit, sand and cement stone can be discharged from the grinding process as coarse-grained material. This still poorly pretreated material is detected by the sorting process and can be fed back to the grinding process in the bed according to the invention.

  Subsequent separation by screening is appropriate to separate grit and sand. The material carried by the process air stream to the classifier is classified there. Depending on the settings of the classifier, for example, only finely divided cement stone is discharged as fines, while the remaining material is fed back to the grinding pan. The comminution of the cement stone is carried out essentially not through compressive stress but instead through grinding in the bed, corresponding to the process according to the invention. In other words, the cement stone is powdered by other particles and other cement stones. Through this powdering it is also possible to remove cement stone from sand and grit without grinding the sand and grit itself.

  The process according to the invention can preferably be carried out by means of a roller mill. The roller mill is a rotatable grinding pan on which a grinding bed of grinding material is formed during operation, rolling on the grinding pan and the grinding material during operation And at least two stationary rotatable grinding rollers. In this case, the classifier is preferably located above the grinding roller, and in addition means are provided for defining and maintaining a minimum grinding gap between the grinding pan and the grinding roller.

  The vertical roller mill according to the invention requires, in in-bed grinding, a significantly lower compression on the ground material in the grinding bed than, for example, the conventional grinding beds present for coal grinding. It is based on the recognition that it is or may occur. However, through the effect of this low compression or force through the grinding roller, there are problems related to locally different hardness and problems related to additional properties of the grinding bed which can be of distinctly different levels. For example, as a result of low compression and relatively high mill bed height, there may be more air content at some points than others. If the grinding roller is operated with a constant pressing force, there is a risk that the grinding roller compresses the grinding bed considerably more than at other points in that more air content is present. Furthermore, it can happen that the grinding roller impacts up to the grinding pan. All these changes and the resulting phenomena lead to the operation of the grinding roller which is not smooth. And this leads to oscillations of the overall operation of the vertical mill, which may be undesirable and may be partially harmful. For example, the pretreatment process using a vertical roller mill must be stopped if too much vibration occurs.

  In this connection, it has been recognized that in the present invention it is necessary, for the first time in a vertical mill, to provide means for defining and maintaining a minimum grinding gap between the grinding pan and the grinding roller. . This measure ensures that the grinding roller is prevented from impacting on the grinding pan through the different properties of the grinding bed.

  Different possibilities are conceivable to implement this measure. In an advantageous embodiment, it is possible, for example, to provide a corresponding stopper or stop buffer for the grinding roller. Another possibility is to correspondingly design the hydraulic system of the grinding roller.

According to a preferred embodiment, a hydraulic system is provided to adjust the pressing force of the grinding roller during operation. The hydraulic system, to the projected area in the vertical direction of the mean roller diameter in order to promote the contact pressure in the range from 15 kN / m ² up to 140kN / m ^2, the weight of the force of the grinding roller Compete. Hydraulic systems in vertical roller mills, in particular of the LOESCHE type, are conventionally designed such that the pressing force of the grinding roller acts in the same direction as the force of weight. Usually, the hydraulic system, the contact pressure from 600 kN / m ² up to 1000 kN / m ² or more comes to be realized. However, this is undesirable in in-bed grinding.

  Due to the size of the grinding roller in different milling systems, and its weight of up to 45 t, it is necessary to provide a reverse hydraulic system to reduce the force of the grinding roller's weight pressing onto the grinding bed It is. The hydraulic system already known, in part, is used to pivot the grinding roller out, which can not be used here. The reason is that although it actually reduces the pressure of the grinding roller above the grinding bed, it is not suitable to maintain this pressure and thus the pressing force at a constant level. Instead, it is merely designed to pivot the grinding roller out quickly, for example, for maintenance purposes.

  According to an advantageous embodiment, a monitoring system is provided on each grinding roller to monitor the rotation of the grinding roller during operation. This is necessary when using a vertical roller mill for in-floor grinding. The reason is that, as already mentioned, the work is carried out with a very low pressing force, which means that it may occur that the grinding roller no longer rotates sufficiently. By providing a monitoring system, it is possible to detect this situation and appropriate measures are triggered, eg temporarily increasing the pressing force.

  The invention will be described in more detail below by reference to the drawings using schematic exemplary embodiments.

FIG. 2 shows a flow diagram for concrete pretreatment according to the invention. It is a figure which shows the cross section of a vertical roller mill. FIG. 3 is a cutaway view of the vertical roller mill of FIG. 2;

  FIG. 1 shows a flow diagram 10 for pre-treating crushed concrete as an example for the inventive method for pre-treating and separating materials comprising multi-material based composites. The method for the pre-treatment of crushed concrete, which is described in more detail below, uses in the same or similar manner for other material systems in which the individual components do not have ductile properties Is also possible. The following design is to be considered merely as an example to illustrate the exact implementation of the method according to the invention and to illustrate the advantages thereof by way of example. Also, the individual method steps described in correlation with this example can be carried out individually and therefore each should be considered separately as part of the present invention.

  Conventionally, concrete particulates are produced from crushed concrete, through breaking and reinforcing steel separation, in parts from 0 mm to 63 mm. Subsequently, classification into grit and sand parts is usually performed. However, these parts still have considerable cement stone adhesion that can not be ignored. Therefore, for aggregate in concrete products, it is technically justified to use recycled grit and sand up to 15% as primary grit and sand replacement. It is considered to be.

  This maximum 15% threshold of material recycled as grit and sand replacement can be clearly improved by the method according to the invention.

  For this purpose, concrete granules having a size of up to 80 mm are used as starting material or feed product 11. This concrete granulate is also described as crushed concrete, which is fed to the roller mill 12 according to the invention as feed material. The roller mill 12 is operated in the manner according to FIG. 1 in the combined mode of overrunning and air stream and is also described as a vertical roller mill. The processes carried out in the roller mill 12 and the mode of operation of the roller mill 12 will be described in more detail below with reference to FIG.

  The roller mill 12 is operated according to the invention not as a comminution unit but as a grinding unit in the bed. Thus, the pretreated and pulverized cement stone 16 can be removed from the pretreatment circuit in a classifier provided in the roller mill 12 and the classifier could in principle be a roller It is also possible to arrange downstream of the mill 12.

  By overrunning, the coarse material 13 is removed from the pretreatment in the roller mill 12 and the coarse material 13 consists essentially of pretreated grit, sand, and a material still adhering. However, the proportion of the material still adhering is clearly smaller than the proportion in the feed material 11. The material with adhesion can be, inter alia, grit and / or sand with adhesion of cement stone. Thereafter, the coarse-grained material 13 is exposed to the screen 14 which allows the sand 17 to be removed as a fraction of 0 mm to 2 mm. This sand 17 is sufficiently refined through the method 10 according to the invention so that it can be used as well as the original sand in the concrete product.

  The coarse-grained material 13 having a size of more than 2 mm is subsequently exposed to the density sorting means 15. This serves to allow the purified grit 18 with higher density to be drained from the processing circuit. And materials that do not have a sufficiently high density, which are, inter alia, grit and / or sand where adhesion of cement stone is still present, to grinding in the bed in the roller mill 12 It is fed.

  However, furthermore, methods which are not described herein are conceivable, sand is also fed to the density sorting means to separate any adhesion of cement stone or other impurities which may still be present, to the grinding mills To feed again.

  Thus, according to the method 10 according to the present invention, grit 18 and sand 17 are extracted with high purity from crushed concrete, in particular concrete granules 11, these components being similar to the original grit and sand in concrete products It is possible to be able to be used. Thus, a much higher recycling rate is realized than the 15% rate possible to date.

  Density sorting may be realized as dry density sorting, for example by means of a wind classifier, air jigs and / or air fluidized bed sorting. Alternatively, it is also possible to carry out wet density sorting. However, the material fed back to the roller mill 12 must then be dried again. Possible exemplary wet sorting methods are sink-or-swim separation methods, both static and dynamic setting sorting methods, spiral separator or hearth sorting methods, and fluidized beds It is a sorting method.

  The roller mill 12 and its operation for grinding in the bed will be described in more detail below by referring to the detailed FIG.

  FIG. 2 shows a schematic cross-sectional view of a vertical roller mill 30 of the LOESCHE type. The essential elements of the roller mill 30 are constituted by a frusto-conical grinding roller 31 rolling on a grinding bed 41. In the partial cross-sectional view shown here, only two grinding rollers 31 are shown. However, it is also possible to use a vertical roller mill 30 with three, four, six or more grinding rollers.

  The grinding bed 41 is formed on the grinding pan 32. The grinding roller 31 can also be described as a roller, and although the grinding roller 31 itself is provided in a fixed position, it can be rotated about the axis shown in the drawing. The grinding pan 32 is then rotatable about its central axis, as shown. If the grinding pan 32 is rotated, the grinding material 42 present above the grinding bed also rotates. Here, the grinding roller 31 is set to rotate through the friction between the grinding material 42 and the outer contour of the grinding roller 31.

  The classifier 34 is provided above the grinding pan 32 and can be designed both dynamically and statically. The in-bed milling process according to the invention is described in more detail below.

  Feeding material or grinding material 42, for example, crushed concrete, is fed to the pretreatment process via material feeding 35. Here, the material feed 35 is formed such that the feed material 42 is fed into the central area of the grinding pan 32.

  Through rotation of the grinding pan 32, the grinding material is, on the one hand, accelerated and, on the other hand, spirally transported outward so that the grinding roller 31 rolls on the grinding material. However, corresponding to the in-bed grinding method according to the invention, the grinding roller 31 is operated in a manner different from that generally known in the roller mill 30. Here, they are not essentially used for pressure milling of the grinding material.

Corresponding to the method according to the invention, only an extremely low contact pressure is applied to the grinding bed 41 by the grinding roller 31. This is in the range of 15 kN / m ² up to 140 kN / m ² . Preferably, it is, inter alia, in the range between 30 kN / m ² and 80 kN / m ² . This contact pressure essentially serves to introduce a sufficiently large shear force into the grinding bed 41 so that the particles present there are mutually comminuting.

  The grinding rollers usually have an average diameter of at most 2.8 m and a weight of at most 45 t. With this large weight, a contact pressure which is considerably higher than what is maximally possible with grinding in the bed is achieved. For this reason, a reverse hydraulic system (not shown in FIG. 2) is provided which is used to counter the force of the weight of the roller 31. This hydraulic system can engage the rocker arm 33 of the grinding roller 31 as a negative force. In other words, the reverse hydraulic system pushes on the rocker arm 33 such that the roller 31 is raised slightly and a force against its weight force acts on the roller.

  Through the further feeding of fresh grinding material 42 and through the rotation of the grinding pan 32 (which can also be described as a grinding plate), onto the grinding pan 32 which has already been partially pretreated. The positioned material is displaced and also overflows the retaining rim 36 into the gap between the grinding pan 32 and the mill housing.

  A first classification is performed at this point throughout the operation of the mill, in both overrunning and airstream modes. A proportion of the overrun treated material is transported in the direction of the classifier 34 by the process air 37 coming from below, whereby another proportion is treated as an overrun coarse-grained material. It can be removed from

  An essential feature of the first classification is the amount of process air 37 supplied. In addition, the classification may also be affected by the blade ring 38. Here, the process air 37 is regulated in combination with the blade ring 38 so that essentially grit and sand can be removed from the processing circuit as the overrunning coarse-grained material 51. This is then subjected to screening as described by reference to FIG.

  Also, grit and / or sand adhesive material with cement stone that has not yet been sufficiently ground can be removed from the processing circuit as overrunning coarse material 51. The adhesive material is then fed back to the treatment circuit with fresh crushed concrete, as already described in connection with FIG.

  A first classification, which may be considered as density sorting, is performed through the process air and optionally provided blade rings.

  Processed air 37 carries, among other things, finely divided cement stone and particles of sand with adhesive cement stone to classifier 34. A second classification is performed here. And this is also density sorting.

  Here, with the aid of the classifier 34, cement stone, which is particularly finely divided, is discharged from the processing circuit. This finely divided cement stone is removed from the processing circuit with the exiting process air at the process air outlet.

  Insufficiently milled cement stone or adhesive material comprising cement stone and sand is fed back to the grinding pan 32 via the grit cone 40 where it is fed to grinding in a further bed Be done.

  In addition, a roller speed sensor 46 is provided on the roller 31, which detects the speed of the roller 31 during operation. This is necessary because it can cause the roller to rotate too slowly, through a low pressing force (the roller 31 is pressed onto the grinding bed in attrition in the bed by the low pressing force). If this is detected by the roller speed sensor 46, it is possible to temporarily increase the pressing force and thus increase the rotation of the roller.

  The essential feature of the process according to the invention and the successful in-bed grinding make the grinding bed sufficiently tall that sufficient particles of feed material are present to enable mutual grinding. Is to design. Values that may be relevant for the grinding bed will be described in more detail below in FIG.

  FIG. 3 shows a cutaway view of the roller mill 30 of FIG. The same reference numbers as in FIG. 2 are further used here.

In order to influence the height s of the grinding bed, essentially, the feed mass flow m _{m, in} , the pressing force F _w of the grinding roller 31, the rotational speed n _s of the grinding pan , the height h of the holding rim 36 , And inner circulation flow rates are available. Here, the inner circulation flow rate is not shown in FIG. It is essentially the material that has been eliminated by the classifier that occupies a portion of the feed mass flow mm _{, in} .

  The influence of the individual setting parameters will be explained in more detail below, in each case the other parameters will be explained under the assumption that they remain constant in relation to this . The goal here is, inter alia, to change the height s of the grinding bed under the roller 31, ie the height of the grinding bed between the roller 31 and the grinding pan 32. This area is also known as the grinding gap.

In a simple manner, the height s of the grinding bed can be varied by changing the pressing force F _W of the roller 31 which influences the contact pressure. The contact pressure is the force acting beneath the roller above the grinding bed. If the pressing force F _{W of the} roller is increased, the ground material is more compressed or pulverized so that the height s of the grinding bed is reduced. Conversely, if the roller 31 is pressed onto the grinding bed 41 with a lower pressing force F _W , the grinding bed height s increases.

An increase of the feed mass flow m _{m, in} increases the grinding bed height s. If more material per unit time is fed to the grinding pan 32, more grinding material will be on the grinding pan 32, under the assumption that the residence times on the grinding pan are equal. Be positioned. Therefore, forcing the mass flow rate m _m on the _mill, resulting in _on it is also increased. As a result, as more material is present on the grinding pan 32, the height s of the grinding bed will also be higher.

The influence of the feed mass flow mm _{, in} can be done in two ways. On the one hand, it is possible to feed more feed material to the roller mill 30 per unit time. On the other hand, it is possible to set the classifier differently so that a higher rejection rate is present in the classifier, which means that more material is fed back to the grinding pan 32. I mean. It is also possible to increase the rejection rate by increasing the process air stream. The reason is that in this case less ground material is removed downwards from the processing circuit as coarse-grained material, but instead is transported to the classifier as potential fines. The feed mass flow m _{m, in} and the inner circulation flow essentially affect the exhaust mass flow m _{m, out} . If the inner circulation flow rate is increased, it is referred to that the circulation load is increased. In other words, more material is positioned in the pretreatment circuit in the mill. This means that, in a different way of expression, the exhaust mass flow m _{m, out} can be reduced over at least a long time. If the feed mass flow m _{m, in} is increased, and thus more feed material is fed to the mill, the discharge mass flow m _{m, out} is also forced to increase.

A different possibility for changing the height of the grinding bed is to increase the rotational speed n _{s of the} pan. If this is increased, then the height s of the grinding bed is reduced. The higher grinding pan rotational speed n _s reduces the residence time of the material to be processed on the grinding pan 32. Thus, the mass flow m _{m, on} above the grinding pan is also lower. Also, the height s of the grinding bed is now forced to decrease.

A further possibility to influence the grinding bed height s is the retaining rim 36. If the height h is to be increased, more material is built on the grinding plate. This is, in principle, that more material must be present on the grinding pan 32 so that more material can flow from the grinding pan 32 with a discharge mass flow m _{m, out} It means that.

An essential feature of all the parameters mentioned here is that they influence each other mutually. In fact, the higher retaining rims 36 lead on the one hand to a higher grinding bed and on the other hand to a longer residence time of the feed material on the grinding pan 32. This leads to good attrition between the rollers 31, depending on the pressing force F _W of the rollers 31, but also, under certain circumstances, to an undesirably long stress period and thus, as a whole, specific Under circumstances, leads to lower throughput.

  By way of example, the individual features of the method according to the invention and the vertical roller mill according to the invention have now been shown in combination. However, it is clear that it is also possible to use each of these features individually.

  Similarly, inter alia, in FIGS. 1 and 2, the example relates to the pre-treatment of crushed concrete. However, the method according to the invention can also be used to pretreat and separate many different multi-material based composites. For example, grinding in the bed in a roller mill (which in other words promotes the mere frictional stress of the material to be treated and does not constitute any actual milling) is a natural slate It can be used for pre-treatment of Natural slate is composed of clayey shale and impurities such as lime, ore, or other organic components. Here it is essential to ensure the frictional stress of the natural slate in order to produce a crushed slate, in which, in spite of its fineness, in the crushed slate, the individual particles are plate-shaped Continue to have form.

  Likewise, this method is suitable for treating mica composed of layered silicates and potential impurities. Until now, mainly pure sediments have been used. However, this is the only case, as until now no suitable pretreatment method for dry grinding and separation was known.

  The process according to the invention can also be used to pretreat kaolin containing industrial sand composed of kaolin, feldspar and silica sand. Use and pretreatment of graphite ore (which is composed of graphite and ore matrix), use and pretreatment of clay or bentonite contaminated with sand or non-layered silicate, and sticky component Decomposition through grinding of heavy mineral sands to separate and, below, density separation of rutile, zircon, ilmenite etc. from the surrounding sand part is possible using the method according to the invention. Even FeCr slag, which is composed of slaking slag, can be pretreated corresponding to the metal and the stabilizing slag under certain circumstances. However, the essential feature here is that the metal component must be a non-ductile component. The reason is that otherwise grinding by the method according to the invention is not possible, and otherwise it is not possible to realize the frictional stresses according to the meaning of the invention.

  Thus, it is possible to pretreat and separate multi-material based composites simply and efficiently using the method according to the invention and the roller mill according to the invention.

Claims (13)

A method for pretreatment and separation of materials comprising multi-material based composites, comprising:
The multi-material composite material is composed of at least a first component and a second component connected to the first component, and both of the two components have ductility characteristics at all. Not,
Said material is fed as feed material (42) to a roller mill (30) equipped with a grinding pan (32) and a grinding roller (31) for grinding in the bed.
A grinding bed (41) comprising the material to be treated and the treated material is formed on the grinding pan (32) during operation,
The grinding roller (31) rolls on the grinding bed (41) during operation,
The material is, during grinding in the bed, by means of the grinding roller (31) on the grinding bed (41), through the shearing force between the particles of the component itself and the grinding, And separated into said second component, said particles of said first component, said particles of said second component, and particles of the same component being mutually milled,
For milling of the bed, the roller mill (30), with respect to a vertical projected area against the roller mean diameter, in order to realize the contact pressure in the range from 15 kN / ^{m 2} up to 140kN / ^{m 2} , the pressing force of the grinding roller ₍₃₁₎ (F W) is operated by only the pressing force (F _W) consists essentially of finely ground pressure base of the first and / or the second component Is selected so as not to be carried out directly by the contact pressure,
The roller mill (30) is operated such that the grinding bed (41) has a minimum height which is greater than the diameter of the particles of one of the two of the components.
To pretreat and separate materials comprising multi-material based composites, characterized in that at least the first and the second component are removed from the processing circuit of the roller mill (30) and sorted. the method of. The method of claim 1, such that the shear forces between the particles themselves which are created between the grinding of the bed is in the range from 5 kN / m ² to 70 kN / m ^2, A method characterized in that the pressing force is selected.   Method according to claim 1 or 2, characterized in that the height of the grinding bed is controlled to at most 8% of the diameter of the grinding pan.   The method according to any one of the preceding claims, wherein the height of the grinding bed is controlled to approximately 4% of the diameter of the grinding pan. A method according to any one of claims 1 to 4, the pressing force required together with (F _W), the grinding bed height (s) is, the feed mass flow rate (m _{m, in} ), the rotational speed of the grinding pan (n _s), the height of the retention rim of the grinding pan (32) (h), and / or, wherein the regulated by inner circulation flow rate. 6. A method according to claim 5, wherein if the material binding of the multi-material system is increased, the pressing force ( _Fw ) is increased to achieve grinding in the bed. In order to maintain the height (s) of the grinding bed, the feed mass flow (m _{m, in} ) is increased, the height (h) of the retaining rim is increased, and the inner circulation flow is increased. Method characterized in that it is increased and / or the rotational speed ( _ns ) of the grinding pan is reduced. A method according to any one of the preceding claims, wherein the feed mass flow (m _{m, in} ) is increased to maintain the height of the grinding bed _{, in} order to increase the throughput. A method characterized in that the rotational speed ( _ns ) of the grinding pan is increased. A method according to any one of the preceding claims, wherein the roller mill (30) is higher during start-up than the pressing force ( _Fw ) selected during operation. Method characterized in that it is operated by the pressing force (F _w ) of the roller (31). A method according to any one of the preceding claims, characterized in that the roller mill (30) is operated in overrunning and / or air stream mode . A method according to any one of the preceding claims , wherein crushed concrete comprising grit, sand and cement stone is delivered as material.
Process characterized in that grit and sand are separated from each other and from cement stone by grinding in said floor . The method according to claim 10 , wherein a vertical roller mill comprising a classifier (34) is used.
Cement stone and at least partially a composite of cement stone and sand from crushed material overrunning from the crushing pan (32) are transported to the classifier (34) by a process air stream The process air stream is conditioned, grit and sand are removed from the grinding process as coarse-grained material, and the finely divided cement stone is removed from the grinding process as fines in the classifier (34) Cement stone and a composite of cement stone and sand are eliminated by the classifier (34) and fed back to the grinding pan (32).
Method characterized in that sand is separated from said discharged coarse-grained material by screening . Grinding pan (32), which is a rotatable grinding pan (32), wherein during operation a grinding bed (41) of grinding material (42) is formed on said grinding pan (32);
At least two stationary rotatable grinding rollers (31), rolling on said grinding bed (41) during operation;
A classifier (34) disposed above the grinding roller (31);
Means for defining and maintaining a minimum grinding gap between the grinding pan (32) and the grinding roller (31)
A vertical roller mill comprising
The pressing force (F) of the grinding roller (31) during operation _W The reverse hydraulic system is provided to adjust the above-mentioned reverse hydraulic system, and the reverse ² To 140 kN / m ² A vertical roller mill that opposes the force of the weight of the grinding roller to promote the contact pressure in the range up to. A vertical roller mill according to claim 12, wherein a monitoring system (46) is on each grinding roller (31) to monitor the rotation of the grinding roller (31) during operation. It is provided, vertical roller mill.

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