WO2015051925A1

WO2015051925A1 - Method and device for preparing and separating a material from a combined multicomponent system

Info

Publication number: WO2015051925A1
Application number: PCT/EP2014/055685
Authority: WO
Inventors: Dirk Van Mechelen; André BÄTZ; Andreas Jungmann; Holger Wulfert; Paul ERWERTH
Original assignee: Loesche Gmbh
Priority date: 2014-03-21
Filing date: 2014-03-21
Publication date: 2015-04-16
Also published as: CN105102132B; BR112015011596B1; AR099817A1; BR112015011596A2; KR20150112927A; CN105102132A; HK1208002A1; RU2015118815A; JP2017513709A; EP2903744A1; TW201540365A; TWI680802B; SG11201503809VA; JP6522731B2; KR101908906B1; IL238733A0; RU2648705C2; EP2903744B1

Abstract

The invention relates to a method for preparing and separating a material from a combined multicomponent system. The material is fed to a roller mill as feedstock. An in-bed attrition is carried out in a grinding bed by means of grinding rollers in the roller mill, said material being attrited by shearing stresses and abrasion. In the process, the roller mill is operated such that the grinding bed has a minimum height which is greater than the diameter of one of the particles of one of the two components, and the pressure force of the rollers is selected so as to achieve a surface pressure ranging from 50 kN/m² to 140 kN/m² relative to the perpendicularly projected surface of the central roller diameter. The invention further relates to a vertical roller mill which is developed in order to carry out the method according to the invention.

Description

Method and apparatus for preparing and separating a material from a joined multi-material system

The invention relates to a method for processing and separating a material from a bonded multi-fuel system as well as a vertical roller mill for carrying out this method.

In Germany, about 80 million tons of construction waste accumulate annually. Much of this is Betonbruch. Concrete and thus also concrete break consist essentially of gravel, sand and cement. Among other things, the cement stone serves to bind the other two components.

Especially in areas where no natural gravel and sand deposits are present, it is desirable to treat the concrete fracture so that it can be separated into its individual components. In particular, there is interest in the recovery of the gravel and / or sand used. However, it is essential here that the gravel and the sand are cleaned as completely as possible from the cement paste, since otherwise, when the said reclaimed gravel or sand is used for the production of concrete, the concrete thus produced may have lower strengths.

From WO 201 1/142663 A1, for example, a separating device is known in order to crush concrete fracture and, if possible, in this case also be able to recover the individual components of the concrete. However, with this device, the desired levels of purity of the individual recycled components such as gravel and sand can not be achieved or only under particularly favorable circumstances. Essential in concrete recycling is that in particular the gravel should not be crushed in the treatment of concrete fracture, otherwise he can only be used inferior for the production of concrete.

Recently, roller mills, which are actually pure comminution units, are used for the treatment and separation of materials.

Such a method is known, for example, from WO 201 1/107124 A1. In the process described there, stainless steel slags, which consist of a silicate fraction and a metal fraction, are selectively comminuted and separated from one another. During comminution, one makes use of distinct hardness differences between the individual fractions as well as density differences in order to achieve a separation. It is essential in this method to continue to use the mill primarily as a crushing unit and to significantly reduce the abandoned raw materials, and only to achieve a separation as a secondary downstream property. The necessary pressure-related comminution can be achieved with this method, a separation only if one of the components to be separated is ductile, so that it is not crushed during the grinding process. In other words, the separation is made by crushing one component by the roller pressure while not crushing another one. This is possible because the component not to be shredded has ductile properties. At a slightly too high grinding pressure, this component deformed, which is unintentional, but it is still not crushed.

Such a method, however, can not be used for the treatment and separation of concrete fracture, as there are no ductile partial materials in the case of concrete fracture, and thus all partial materials or components of the concrete fracture would be comminuted by the mill. Thus, the desired result, in particular a cleaning and recovery of the gravel, can not be achieved.

It is an object of the invention to provide a method and a device with which efficient preparation and separation of a material from a connected multi-substance system is possible, in which the components of the multi-substance system have no ductile properties. This object is achieved by a method for processing and separating a material from an associated multi-component system with the features of claim 1 and a vertical roller mill with the features of claim 13.

Advantageous embodiments of the invention are specified in the subclaims and the description.

In the method according to the invention for preparing and separating a bonded multi-component system from at least one first component and a second component, which is connected to the first component, and wherein both components have no ductile properties, the material of a roller mill, which has a grinding bowl and grinding rolls , abandoned for in-bed attrition as a feed.

During operation, a grinding bed of machined and machined material is formed on the grinding bowl, on which the grinding rolls roll. In in bed Attrition the material is separated by shear stress and abrasion of the particles of the components with each other in the first and the second component by means of grinding rollers in the grinding bed, the particles of the first component, the particles of the second component and particles of the same component each other attri - be killed.

To enable the in-bed attrition in the roller mill this is operated with an extremely low contact pressure of the rollers, so that a surface pressure only in the range of 15 kN / m ² to a maximum of 140 kN / m ² based on the vertically projected area of the middle Roll diameter is achieved. Here, the contact pressure is chosen so that directly by the surface pressure directly essentially no pressure-induced comminution of the first and / or second component is performed. In other words, the preparation of the material takes place essentially only by the attrition of the material or of the particles of the first and / or second component mutually. A pressure-related crushing is not provided. If a comminution is carried out, this is done mainly by the juxtaposition of the material. Furthermore, 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. Subsequent to the in-bed attrition or the machining in the grinding bed, at least the first and the second component are removed from the processing circuit of the roller mill and sorted.

A basic idea of the method according to the invention can be seen in using a roller mill, in particular a vertical roller mill, no longer as a comminution unit, in which the material to be comminuted is "crushed" by the pressure of the rollers, but the roller mill, in particular that formed on the roller mill Grinding bed, for the separation and preparation of the feed material into its constituents, in particular into the first and second components, This separation and processing of the feed material takes place within the grinding bed by mutual frictional stress, ie attrition of the material.

According to the invention, it has been recognized that an attrition process between the individual components of the material, which consists of the connected multi-substance system, occurs or is made possible only by the inventive design of the grinding bed with only extremely low compressive stress by the rollers in the grinding bed.

By utilizing the in-bed attrition according to the invention, it is thus also possible to use a roller mill to separate multicomponent systems whose components have no ductile properties. It is even possible to carry out such a separation in multi-component systems whose components are brittle. In other words, essentially no grinding takes place in the mill, since the contact force of the rolls is dimensioned so that substantially no further comminution is possible by the rolls or their action on the grinding bed. The separation and the associated partial comminution of the components of the multi-component system are mainly achieved by the attrition process, which takes place in the grinding bed.

In the context of the invention, under attrition or attritioning, the purification of several components of adhesions with one another by mutual ges rubbing be understood. In this case, the separation of the components takes place, in particular, by the shearing forces on the surfaces which arise when friction occurs, which lead to a cleaning of the individual components.

Another basic idea on which the invention is based is to design the grinding bed such that it has a minimum height, which is greater than the diameter of the particles of one of the two components. Here, in particular, the harder or tougher of the two components of the joined multi-component system is selected. This design of the grinding bed ensures that the harder component is not comminuted by the roller pressure. In this context, it does not necessarily have to be the hardest of the components. For example, it is also advantageous if the Mahlbetthöhe is at least as high as the average size of one of the components. In this way, it is ensured with sufficient likelihood that during the preparation process it does not come to a pressure-related comminution but essentially to the preparation or comminution due to attrition processes in the grinding bed, that is to say rubbing comminution.

For the purposes of the invention, the connected multicomponent system may also consist of more than the two components exemplified here. As a harder component can be understood in the context of the invention, the better cohesive component.

The preferred selected pressing force of the rollers, which may alternatively be referred to as grinding rollers is selected so that a surface pressure in the range of 15 kN / m ² to a maximum of 140 kN / m ² occurs. The contact pressure depends, among other things, on the size of the rolls, the size of the vertical mill and / or the weight of the rolls. The reference pressure used here is the surface pressure, so that a guide size is available irrespective of the size of the rollers or mill. The preferred range of the surface pressure depends on the materials to be processed, wherein the surface pressure is chosen so that there is essentially no pressure-related comminution of the material to be ground. Since many different hardnesses are present over the entire width of the multicomponent system when processing a natural multicomponent system, it is also possible can not be completely excluded by the method according to the invention that a small part of an undesired pressure crushing is subjected o- can not be successfully processed.

The invention is further based on the surprising finding that, despite the fact that the surface pressure is actually too low for the operation of a roller mill, it is possible to machine the material to be charged. This is essentially due to the fact that, in contrast to the previous operating mode of the mill, no actual grinding takes place, but the materials essentially process one another and are not processed by the rollers. This even leads to the fact that with the inventive method, a treatment and separation of materials is possible whose components have substantially no density differences.

Advantageously, the contact pressure is chosen such that, in the case of in-bed attrition, shearing forces between the particles are in the range from 5 kN / m ² to 70 kN / m ² , in particular between 7 kN / m ² and 20 kN / m ² , The ranges given for the shear forces between the particles of the various components of the bonded multi-component system allow good attrition in the grinding bed so that the processing and separation of the connected multi-component system can be carried out in the mill. This can be achieved by the existing shear forces and a sufficiently large purity of the individual components with each other, without risking excessive crushing.

One component that is essential in adjusting the shear forces is the contact force of the rollers. This should ideally be adjusted so that the desired shear forces occur in the grinding bed by the rotation of the grinding table in combination with the rollers and the rotation of the rollers. In other words, different shear or friction forces act on the material to be processed: On the one hand, the shear and frictional forces of the individual material particles with one another; on the other hand, the shear forces that are applied to the material via the rollers.

Normally, when using a roller mill as a crushing unit, the rollers are rotated by the grinding bed. In the standard state can Therefore, assume that the peripheral speed of the rollers is similar to the relative speed of the grinding bed, which is located on the rotating grinding table. However, if the rollers turn more slowly than the grinding table or the grinding bed, the different speeds at the points of contact result in the formation of shear forces which are used for the in-bed attrition according to the invention.

More specifically, the generation of shear forces is essentially due to the velocity of the particles passing under the mill compared to the peripheral speed of the roller passing the particles or past the particles.

In contrast to the standard mode of operation during grinding with a roller mill, in the method according to the invention it is necessary to increase the grinding bed height significantly. For the process according to the invention, the grinding bed preferably has a maximum height of 8% of the grinding bowl diameter, but preferably about 4% of the grinding bowl diameter. In the conventional operation of a roller mill, the material to be ground is actively comminuted or crushed by the rollers. Here, it is desired that the grinding gap, that is, the distance between the grinding rollers and the grinding table or the grinding bowl, is not too large, so that the forces introduced by the grinding rollers in the grinding bed forces can be used actively for crushing the ground material. If the grinding gap is too large, it may happen on the one hand that the material to be ground is in some cases only compacted and thus no sufficient pressure is applied to the material to be ground, and on the other hand that the material to be ground flows out of the grinding gap, so that it displaces but does not break up becomes.

In contrast, according to the mode of operation according to the invention, it is desired that movements of the particles or components of the multicomponent system to be treated occur in the grinding bed. Therefore, it is preferred if the Mahlbetthöhe is significantly higher than Wälzmühlen, which are used exclusively for grinding. Due to the higher Mahlbetthöhe it comes to more relative movements of the particles or components in the grinding bed with each other, so that in this way the in-bed attrition is achieved. In principle, the Mahlbetthöhe can be adjusted by means of the contact pressure of the rollers, a feed mass flow, a Mahlschüsseldrehzahl, a height of a storage edge of the grinding bowl and / or an internal circulation flow.

In this case, an increase in the contact force of the grinding rolls by an associated increase in the surface pressure reduces the Mahlbetthöhe. An increase in the feed mass flow, that is, more millbase per unit time of the roller mill is supplied as feed, increases the Mahlbetthöhe. In contrast, a higher Mahlschüsseldrehzahl again reduces the height of the grinding bed, since the existing ground material is removed faster from the grinding bowl again. The stowage area of the grinding bowl is located at the edge of the grinding bowl and serves to reduce or hinder a runoff of the ground material on the bowl. If the storage margin is increased, so does the height of the grinding bed.

Another parameter that can be used to set the grinding bed height is the internal circulation flow. These are, in particular in roller mills with integrated sifter, the amount of particles which are rejected during the sighting and are returned to the grinding bowl for further processing. If the internal circulation flow is increased, the grinding bed height also increases. The internal circulation flow can be influenced for example by means of the classifier settings as well as by means of the volume of the process air flow.

For example, it has proven to be advantageous if the material binding of the multicomponent system is increased, to increase the contact pressure, in order to achieve the necessary forces for in-bed attrition despite the increased material binding. However, since ideally the Mahlbetthöhe should be kept the same, other parameters must be adjusted because the Mahlbetthöhe is initially reduced by the increased contact pressure. In this case, it is preferable to increase the feed mass flow and / or the inner circulation flow. Alternatively or additionally, the Mahlschüsseldrehzahl can be reduced. The setting of these parameters is also possible during operation, so that if it is found, for example, in tests that the material binding of the multi-component system is higher than before, it can be responded to by the parameters specified here. Another option is to increase the height of the storage area. However, this is not or only with difficulty possible during operation, so that this variation is mainly used when the roller mill used is to be switched to another multicomponent system or designed for this.

Reduces the material bond of the multi-material system, so the contact force is reduced accordingly, which would basically increase the grinding bed. To counteract this, the previously mentioned parameters can now be adapted in the respective opposite direction.

When operating a roller mill, it is generally desirable to process the highest possible throughput, that is, as much as possible feed material per unit of time. If the mass flow rate is increased in order to increase the throughput, it is advantageous if, in particular, the grinding bowl rotational speed is increased in order to maintain the grinding bed height. Increasing the contact force of the rolls would also reduce the millbase height, but this would lead to a change in the in-bed attrition variables. In particular, the higher pressure force of the rollers would increase the grinding pressure, that is to say the force which is introduced into the grinding bed by means of the rollers, as a result of which the surface pressure also increases. This can lead to a poorer treatment and separation of the multicomponent system. Therefore, it is preferred that as the feed mass flow is increased, this is only compensated by an increase in grinding bowl speed. The same can also be done if the internal circulation is forcibly increased. This is the case, for example, when a higher degree of material digestion is required, and therefore less material than fines is removed through the sifter. This leads, as stated previously, to the fact that more material is returned to the grinding table and thereby increases in a similar manner as in the increase of the feed mass flow, the Mahlbetthöhe. Again, it is preferable to control this essentially only by an adjustment, in particular increase, the Mahlschüsseldrehzahl so that the Mahlbetthöhe remains the same.

There are various types of Wälzmühlenty known. In some, the rolls are driven directly, in others, especially in the LOESCHE type, the rolls themselves are not driven, but by the frictional forces, which arise between the rolls and the grinding bed in rotation or Dre- hung. This is relatively unproblematic in the normal operation of a roller mill where the roller mill is used for grinding. When using a roller mill for in-bed attrition, however, it has been found that due to the extremely low contact pressure of the grinding rollers, increased attention must be paid to the rotation of the grinding rollers.

In this regard, it is preferable if the rolling mill is operated at startup with a higher contact pressure of the rollers than the contact force selected during operation. This is necessary in order to initially set the rollers, which have a starting torque to be overcome, in rotation. Subsequently, during in-bed attrition operation, the friction between the grinding bed and grinding rolls is usually sufficient to maintain the rotation of the rolls.

In this regard, it is preferable if the rotation of the rollers is monitored during operation, and the pressing force of the rollers is at least temporarily increased if too little rotation of the rollers is detected. Too low a rotation of the rolls causes the shear forces introduced by the rolls into the grinding bed to change and thus the quality of the in-bed attrition also changes. Due to the short-term increase in the contact force of the rollers is achieved that they have a sufficient rotation or a sufficient angular momentum. For the purposes of the invention, too little rotation of the rollers is understood when the peripheral speed of the roller is less than 50% of the speed of the material flow under the roller. As an approximation, it can be assumed that the flow of material under the roll corresponds to the rotational speed of the grinding bowl or of the grinding plate below the rolls. Depending on the material, adjustments of a few percent may be provided to allow a better estimation of the speed.

In order to facilitate start-up of the roller mill, in particular a set in rotation displacement of the grinding rollers, at the in-bed Attrition only small allowable contact forces, advantageously the roller bearings are designed with a larger game than conventionally. On the one hand, this reduces the starting torque and, on the other hand, also reduces the risk of stoppage or of the grinding rollers having too low a rotational speed. In a preferred embodiment, the roller mill is operated in an overflow and / or air flow mode. In the mode of operation as a pure overflow mill, the prepared ground material is conveyed, inter alia, by the rotation of the grinding bowl over a possibly existing storage area and falls into an area below the grinding bowl. Here it can be transported away. In the mode of operation in the air flow mode, the grinding material falling over the grinding plate is picked up by means of a process air flow and, in particular, blown away upwards. Above the grinding bowl is usually a sifter to which the prepared ground material is transported by means of the process air stream. In the classifier, a sighting takes place, so that sufficiently finely prepared ground material is withdrawn from the preparation process, whereas further to be processed ground material is fed back to the reprocessing process as a so-called reject.

In particular, in-bed attrition is also referred to as a milling process in the context of the invention, as it may be considered as being distantly related to standard milling processes, but differs therefrom by another shredding technique. However, the in-bed attrition is carried out by means of a roller mill, so that the terminology for mills is used for ease of understanding, although in the true sense, grinding no longer takes place. In a combined overflow and airflow mode, the process air stream that passes around the grinding bowl does not absorb all the overflowing regrind, but only a portion thereof. Another part falls down and is transported by means of subsidy from below the grinding bowl.

In a preferred embodiment, the material to be processed and separated from the connected multi-component system concrete fracture. Concrete fracture itself consists mostly of gravel, sand and cement. With the method according to the invention, gravel and sand are separated from one another and from the cement stone by means of the in-bed attrition and cleaned. Due to the in-bed attrition, the cement stone in particular is rubbed off by the gravel and sand, so that, according to the method according to the invention, gravel and sand are again essentially in pure form and can thus be used again for the production of concrete.

In a further advantageous embodiment of the method, a vertical roller mill with separator, which can also be integrated, is used. additionally a process air stream is adjusted so that from the overflowing millbase a component, such as cement paste, and at least partially compounds of the first and the second component, such as cement stone and sand, are transported by means of the process air flow to the classifier, while the first purified component, such as gravel and sand, are removed as coarse material from the grinding process.

It is further provided that at least a portion of the shredded second component, such as comminuted cement stone, is removed as fine material from the grinding process, and insufficiently comminuted particles of the second components as well as adhesions of the first and the second component, such as cement stones and Compounds made of cement stones and sand, rejected by the classifier and returned to the grinding bowl. In addition, sand can be separated from the coarse material withdrawn by sieving, so as to enable further separation in multi-component systems comprising more than two components.

According to an advantageous embodiment, a vertical roller mill is operated in the combined overflow and air flow mode. Here, the process air stream, which sweeps from below around the grinding bowl, adjusted so that it only light or small materials, especially crushed cement stone and adhesions of cement stone and sand, transported upwards towards the sifter. Cleaned heavy components such as sand and gravel can fall down against the process stream and be removed as coarse material from the grinding process. In addition, fused material, which is also called intergrown, can be discharged from the components such as gravel, sand and cement stone as coarse material from the grinding process. This insufficiently processed material can be detected by sorting processes and fed back to the in-bed attrition method according to the invention.

For the separation of gravel and sand, a subsequent separation by sieving is suitable. The material brought to the classifier with the process air stream is sighted there. Depending on the setting of the separator, for example, only crushed cement paste is discharged as fine material, whereas the remaining material is fed back to the grinding bowl. The comminution of the cement stone takes place accordingly the process of the invention essentially not by a compressive stress but by the in-bed attrition instead. In other words, the cement is crushed by the other particles as well as other cement stones. By grinding, it is also possible to remove the cement from sand and gravel, without crushing sand and gravel itself.

The inventive method may preferably with a roller mill with a rotatable grinding bowl, on the operation of a grinding bed is made of ground material and with at least two stationary, rotatable grinding rollers, which roll on the ground during operation run. Here, a sifter is preferably arranged above the grinding rollers and additionally provided a device for defining and maintaining a minimum grinding gap between the grinding bowl and the grinding rollers.

The vertical roller mill according to the invention is based on the finding that in the case of in-bed attrition a significantly lower compression of the ground material on the grinding bed is necessary, or may occur, than with a conventional grinding bed, which is present, for example, during coal grinding. Due to this low compression or force through the grinding rollers, however, there is a problem in connection with locally different hardnesses and other properties of the grinding bed, which can be significantly different pronounced. For example, in some places due to the low compression and relatively high height of the grinding bed more air bubbles may be present than at others. Now, if the grinding rollers operated with a constant contact pressure, so there is a risk that at the points where more air bubbles are present, the grinding rollers squeeze the grinding bed much stronger than at others. It may even happen that the grinding rollers penetrate to the grinding bowl. All these variants and phenomena occurring lead to a troubled run of the grinding rollers, which in turn leads to vibrations throughout the operation of the vertical mill, which can be undesirable and sometimes even harmful. For example, the processing process must be stopped with the vertical mill if excessive vibrations occur. In this regard, it has been recognized in the invention that for the first time in vertical mills it is necessary to provide means for defining and maintaining a minimum grinding gap between the grinding bowl and the grinding rolls. This device ensures that it is prevented that the grinding rollers can penetrate through the different properties of the grinding bed on the grinding bowl.

There are various possibilities conceivable to perform these facilities. For example, in an advantageous embodiment, corresponding stops or stop buffers may be provided for the grinding rollers. Another possibility is to design the hydraulic system of the grinding rollers accordingly.

In a preferred embodiment, a hydraulic system is provided for adjusting the contact force of the grinding rollers during operation, which counteracts the weight of the grinding rollers to a surface pressure in the range of 15 kN / m ² to 140 kN / m ² based on the vertically projected area of the mean roller diameter to enable. Conventionally, the hydraulic system is designed in vertical roller mills, in particular the LOESCHE type, such that the pressing force of the grinding rollers acts in the same direction as the weight force. Normally, a surface pressure of 600 kN / m ² up to 1000 kN / m ² or more should be achieved by means of the hydraulic system. In the case of in-bed attrition, however, this is not desired.

Due to the size of the grinding rolls in different mill systems and their weight of up to 45 tons, it is necessary to provide an inverse hydraulic system to reduce the weight of the grinding rolls pressing on the grinding bed. Here, the already known hydraulic system, which is used partly for swinging the grinding rollers, not be used, since this reduces the pressure of the grinding rollers on the grinding bed, but is not suitable, this pressure, so the contact pressure, at a constant level to hold, but is designed for a quick swinging of the grinding rollers, for example, for maintenance operations.

In an advantageous embodiment, a monitoring system is provided on each grinding roller, which monitors the rotation of the grinding rollers during operation. wakes. This is necessary when using a vertical roller mill for in-bed Attrition, since, as already stated, with very low contact pressure is used, so that it may happen that the grinding rollers no longer rotate sufficiently. By means of the provision of monitoring systems, this state can be detected and appropriate countermeasures can be triggered, for example, the temporary increase of the contact force can be performed.

The invention will be explained in more detail by means of schematic embodiments with reference to the figures. Hereby show:

1 shows a flow chart of a concrete preparation according to the invention;

2 shows a section through a vertical roller mill. and

3 shows a detail of the vertical roller mill from FIG. 2.

In FIG. 1, a flow diagram 10 for concrete fracture treatment is shown as an example of the method according to the invention for processing and separating a material from a connected multicomponent system. The method for treating concrete fracture described in more detail below can also be used in the same or similar manner for other material systems in which the individual components have no ductile properties. The following embodiment is merely exemplary in order to clarify the exact embodiment of the method according to the invention and its advantages by way of examples. In this case, the individual method steps, which are described in a coherent manner in this example, can also be carried out individually and are thus to be considered separately as part of the invention.

Conventionally, concrete granules are produced in fractions of 0 mm to 63 mm concrete breakage by breaking and separating reinforcing steel. Subsequently, a classification is usually carried out in gravel and sand fractions. However, these fractions still have not negligible adhesions of cementum. Therefore, use of recycled gravel and sand from just up to a maximum of 15% considered as aggregate in concrete production as replacement of primary gravel and sand considered technically feasible.

This limit of a maximum of 15% of recycled material as a gravel and sand replacement can be shifted significantly upwards by means of the method according to the invention.

For this purpose, concrete granules having a size of, for example, up to 80 mm grit size are used as starting material or feed product 1 1. This concrete granulate, which is also referred to as concrete fracture, is given to a roller mill 12 according to the invention as a feedstock. The roller mill 12 is operated in the method of FIG. 1 in combined overflow and airflow modes and is also referred to as a vertical roller mill. The processes occurring in the roller mill 12 and the operation of the roller mill 12 will be discussed in more detail later with reference to FIG. 2.

The roller mill 12 is operated according to the invention as an in-bed Attritionsaggregat and not as a crushing unit. Thus, at a provided in the roller mill 12 classifier, which in principle can also be followed by the roller mill 12, processed and crushed cement stone 16 are withdrawn from the treatment cycle.

As an overflow of the preparation in the roller mill 12 coarse material 13 is taken, which consists essentially of processed gravel, sand and still fused material, the proportion of which is significantly lower than the feed material 1 1. The intergrown material may be, in particular, gravel and / or sand with the adhesion of cement stone. Subsequently, the coarse material 13 is subjected to a screening 14, with which the sand 17 can be removed as a fraction of 0 mm to 2 mm. This sand 17 is so well cleaned by the inventive method 10 that it can be used similar to primary sand in concrete production.

The coarse material 13, which has a size of over 2 mm, is then subjected to a density sorting 15. This serves to be able to discharge cleaned gravel 18, which has a higher density, out of the processing circuit. Material which does not have a sufficiently high density - this is in particular Gravel and / or sand, on which cementum stone adhesions are still present, are again supplied to the in-bed attrition in the roller mill 12.

Furthermore, the procedure is conceivable, but not shown here, that the sand is also fed to a density sorting, in order to possibly also remove there any remaining adhesions to cement paste or other impurities and to feed it again to the rolling mill process.

With the method 10 according to the invention, it is thus possible to extract from concrete fracture, in particular concrete granules 1 1, gravel 18 and sand 17 in such a high purity that these components can be used analogously to primary gravel and sand in the concrete production. Thus, a much higher recycling rate than the possible 15% quota is achieved.

The density sorting can be done as a dry density sorting for example by means of wind sifters, air mesh machines and / or air fluidized bed sorting. Alternatively, a wet density sorting can be performed. In this case, however, then the rolling mill 12 again supplied materials must be dried again. As a wet sorting method, for example, floating-sink divorce, both static and dynamic, setting sorting, Wendelscheider- or herdsortierung and Wirbelschichtsortierverfahren possible.

The roller mill 12 and its operation for in-bed attrition will now be explained in more detail below with reference to the more detailed FIG. 2.

FIG. 2 shows a schematic sectional view through a vertical roller mill 30 of the LOESCHE type. An essential component of the roller mill 30 are truncated cone-shaped grinding rollers 31, which roll on a grinding bed 41. In the partial sectional view shown here only two grinding rollers 31 are shown. However, vertical rolling mills 30 having three, four, six or more grinding rolls may also be used.

The grinding bed 41 is formed on a grinding bowl 32. The grinding rollers 31 themselves, which may alternatively be referred to as rollers, are provided fixed, but rotatable about the drawn axis. The grinding bowl 32 in turn is rotatable about its central axis as indicated. If now the grinding Turned bowl 32, so the grinding material 42 present on the grinding bed also rotates. As a result, the grinding rollers 31 are rotated by friction between the ground material 42 and the outer contour of the grinding rollers 31 in rotation.

Above the grinding bowl 32, a separator 34, which can be designed both dynamically and statically, is provided. In the following, the in-bed attrition process according to the invention will now be discussed in more detail.

The feedstock or ground material 42, for example concrete fracture, is fed to the preparation process via a material feed 35. Here, the material task 35 is designed such that the feedstock 42 is abandoned in the central region of the grinding bowl 32.

By the rotation of the grinding bowl 32, the material to be ground is accelerated on the one hand and, on the other hand, transported spirally outwards, so that it is rolled over by the grinding rolls 31. According to the in-bed Attritions- method according to the invention, however, the grinding rollers 31 are operated in a different manner than normally known in Wälzmühlen 30. They are essentially not used here for pressure reduction of the ground material.

According to the method according to the invention, only a very small surface pressure is applied to the grinding bed 41 by the grinding rollers 31. This is in the range of 15 kN / m ² to a maximum of 140 kN / m ² . It is preferably in the range between 30 kN / m ² and 80 kN / m ² . This surface pressure essentially serves to introduce sufficiently large shear forces into the grinding bed 41, so that the particles present therebetween attritieren each other.

Normally, grinding rolls have a mean diameter of up to 2.8 m and weigh up to 45 t. With this high weight, a much higher surface pressure would be achieved than that up to which the in-bed attrition is maximally possible. For this reason, a not shown in Fig. 2 inverse hydraulic system is provided, which serves to counteract the weight of the rollers 31. This hydraulic system can act as a negative force on a rocker arm 33 of the grinding rollers 31. In other words, the inverse hydraulic system pushes on the pivot lever 33, that the roller 31 is slightly raised or acting on the roller a force against its weight.

By the further abandonment of new ground material 42 and the rotation of the grinding bowl 32, which can also be referred to as a grinding plate, the material located on the grinding bowl 32, which is already partially processed, displaced and runs over a storage edge 36 in a gap between Grinding bowl 32 and mill housing over.

By operating the mill in both overflow and airflow modes, a first sighting takes place at this point. A portion of the overflowed machined material is transported by the inflowing process air from below 37 direction sifter 34, wherein another part can be removed as overflowed coarse material from the processing circuit.

In this case, the amount of the supplied process air 37 is essential for the first sighting. In addition, the sighting can also be influenced by a blade ring 38. Here, the process air 37 is set in combination with the blade ring 38 such that substantially overflowing coarse material 51 gravel and sand from the processing cycle can be deducted. This is then screened as described in relation to FIG.

Also, as overflowing coarse 51 and overgrown materials of gravel and / or sand with cement, which has not been sufficiently attritiert be withdrawn from the processing cycle. The intergrown materials are, as already stated with reference to FIG. 1, subsequently returned to the processing cycle with new concrete fracture.

By the process air and the optionally provided blade ring a first sighting is performed, which can be regarded as density sorting.

The injected process air 37 carries in particular crushed cement stone as well as particles of sand with adhesive cement stone to Sichter 34. There takes place a second sighting. Again, this is a density sorting. Here, by means of the classifier 34, in particular, sufficiently comminuted cement stone is removed from the processing cycle. This crushed cement stone is removed from the processing cycle with the outflowing process air at the process air outlet.

Not sufficiently crushed cement stone or fused cement stone and sand material is passed through a semolina cone 40 back to the grinding bowl 32 and there fed to a further in-bed Attrition.

On the rollers 31 in addition roller speed meter 46 are provided which determine the rotational speed of the rollers 31 during operation. This is necessary because it may happen that the rollers rotate too slowly due to the low contact pressure at which the rollers 31 are pressed onto the grinding bed during in-bed attrition. If this is detected by means of the roller speed meter 46, the contact force can be temporarily increased so as to increase the rotation of the rollers.

Essential for the method according to the invention and the successful in-bed attrition is to make the grinding bed sufficiently high so that sufficient particles of the feed material are present, so that a mutual attrition is made possible. Possible influencing variables for the grinding bed are explained in more detail below in FIG. 3.

FIG. 3 shows a detail of the roller mill 30 from FIG. 2. The same reference numerals as in FIG. 2 are used here.

Essentially, the feed mass flow rh _m , in, the contact pressure F _{w of} the grinding rollers 31, the grinding bowl speed n _s , the height h of the storage rim 36, and the internal circulating flow are available for influencing the grinding bed height s. The internal circulation flow is not shown here in FIG. 3. When it is essentially rejected by separator material which riv a part of the object of the mass flow _in mind.

In the following, the influence of the individual adjustment parameters is explained in more detail, in each case assuming that the other parameters remain the same in this context. The goal here is in each case, the Mahlbetthöhe s, in particular below the Rolls 31, that is between the rollers 31 and the grinding bowl 32 to vary. This area is also known as the grinding gap.

In a simple manner, the Mahlbetthöhe s can be varied by a variation of the contact pressure F _{w of} the rollers 31, which influences the surface pressure. The surface pressure is the force acting directly below the rollers on the grinding bed. If the contact pressure F _{w of} the rollers is increased, then the millbase is more compacted or comminuted, so that the Mahlbetthöhe s decreases. Conversely, the Mahlbetthöhe s increases when the rollers 31 are pressed with a lower contact force F _w on the grinding bed 41.

An increase in the feed mass flow rh _m , i _n increases the Mahlbetthöhte s. If more material per unit of time is placed on the grinding bowl 32, then, assuming the same residence time on the grinding bowl, there will be more grinding stock on this grinding bowl. It follows inevitably that the mass flow on the mill rhm.on is increased. Consequently, as more material is present on the grinding bowl 32, the grinding bed height s is also higher.

The influencing of the feed mass flow rh _m , i _n can be done in two ways. On the one hand, the roller mill 30 can be given more feed material per unit of time; on the other hand, the separator can be set differently, so that a higher reject, ie a higher rejection on the separator, is present, so that more material is fed back to the grinding bowl 32 becomes. The reject can also be increased by increasing the process air flow, as in this case less regrind down than coarse material is withdrawn from the processing cycle, but instead is transported as a potential fines to the classifier. The feed mass flow ri _in as well as the internal circulation flow significantly influence the discharge mass flow rh _{m 0} ut- If the internal circulation flow increases, it is said that the circulating load is increased. In other words, there is more material in the processing circuit within the mill. In other words, this means that the discharge mass flow rh _{m 0} ut is at least temporarily reduced. If the task mass flow ri _increased, so more feed the mill added compulsorily also increases the Austragsmassenstrom mm, out- Another way to vary the Mahlbetthöhe is to increase the bowl speed n _s . If this is increased, the grinding bed height s decreases. By a higher Mahlschüsseldrehzahl n _s , the residence time of the material to be processed on the grinding bowl 32 is reduced. Accordingly, the mass flow rh _m , on the grinding bowl is lower. This forcibly reduces the Mahlbetthöhe s.

Another possibility to influence the Mahlbetthöhe s, is the storage area 36. If its height h increased so accumulates more material on the grinding table. This means that in principle more material has to be present on the grinding bowl 32 so that it can flow from the grinding bowl 32 with the discharge mass flow rh _{m 0} .

The essential feature of all the parameters presented here is that they influence each other. Thus, a higher storage edge 36 leads on the one hand to a higher grinding bed, on the other hand to a longer residence time of the feed material on the grinding bowl 32. This leads depending on the contact force F _{w of} the rollers 31 to better attrition with each other, but also under certain circumstances to an undesirable long Stress time and thus overall may be at a lower throughput.

By way of example, individual features of the method according to the invention and the vertical roller mill according to the invention have been shown in combination here. However, it is obvious that these features can also be used individually.

Likewise, the example, in particular in Figures 1 and 2, based on the treatment of concrete fracture. However, the method according to the invention can also be used for the preparation and separation of many different connected multi-substance systems. For example, the in-bed attrition in the roller mill, which in other words allows only a frictional stress of the material to be processed and not actual comminution, also for the treatment of natural shale, which from slate and impurities such as lime, ores or other organic components exists to be used. It is essential to ensure that the natural shale to produce slate flour, in which, despite its fineness, the individual particles continue to have a plate-like shape.

Similarly, the method is suitable for processing mica, which consists of phyllosilicates and possible impurities. Here, mainly pure deposits are exploited until now. However, this is only the case since no suitable treatment methods for dry attrition and separation have been known hitherto.

Likewise, the process according to the invention can be used in the treatment of kaolin-containing industrial sands, which consist of kaolin, feldspar and quartz sand. Also, the use and processing of graphite ore, which consists of graphite and ore matrices, and of clay or bentonite, contaminated by sand or non-layered silicates, as well as the digestion by attrition of heavy mineral sands for separating cohesive constituents and subsequent density separation of rutile, zirconium, llmenit , etc. of an unsatisfied sandy fraction with the method according to the invention possible. Even FeCr slags consisting of disintegrating slag, corresponding metal and possibly stabilized slags can be treated. However, it is essential here that the metal component is a non-ductile component, since otherwise attrition according to the method according to the invention is not possible, since otherwise no frictional stress in the sense of the invention can take place.

With the method according to the invention and the roller mill according to the invention, it is thus possible to prepare and separate multi-substance systems in a simple and efficient manner.

Claims

1 . Process for preparing and separating a material from a bonded multi-substance system,

wherein the bonded multi-material system consists of at least a first component and a second component, which is connected to the first component, and wherein both components have no ductile properties,

wherein the material of a roller mill (30) with a grinding bowl (32) and with grinding rollers (31) for in-bed attrition as Aufgabegut (42) is applied, wherein on the grinding bowl (32) in operation, a grinding bed (41) from formed and machined material,

wherein the grinding rollers (31) in operation roll on the grinding bed (41), wherein in the in-bed attrition by means of the grinding rollers (31) in the grinding bed (41) the material by shearing and abrasion of the particles of the components with each other in the first and the second component is separated, wherein the particles of the first component, the particles of the second component and particles of the same component are attritiert each other,

wherein for in-bed Attrition the roller mill (30) is operated only with a contact force (F _w ) of the grinding rollers (31) to a surface pressure in the range of 15 kN / m ² to 140 kN / m ² based on the projected vertically Reach surface of the mean roll diameter, which is chosen such that the surface pressure directly essentially no pressure-induced comminution of the first and / or the second component is performed, wherein 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 components, and

wherein at least the first and second components are withdrawn from a processing cycle of the roller mill (30) and sorted.

Method according to claim 1,

characterized,

the pressing force is chosen such that the shearing forces between the particles arising during in-bed attrition are in the range of 5 kN / m ² to 70 kN / m ^2, in particular 7 kN / m ² to 20 kN / m ² ,

Method according to claim 1 or 2,

characterized,

that the grinding bed height (s) is controlled to a maximum of 8% of the grinding bowl diameter.

Method according to one of claims 1 to 3,

characterized,

that the grinding bed height (s) is controlled to about 4% of the grinding bowl diameter.

Method according to one of claims 1 to 4,

characterized,

that at a required contact pressure (F _w ), the Mahlbetthöhe (s) by means of a feed mass flow (rh _m , in), a Mahlschüsseldrehzahl (n _s ), a height (h) of a Staurandes the grinding bowl (31) and / or set an inner circulation current becomes.

Method according to one of claims 1 to 4,

characterized,

that the increase in the material binding of the multicomponent system, the contact force (F _w ) is increased to achieve the in-bed Attrition, wherein to maintain a Mahlbetthhehe (s) of the feed mass flow (rh _m , in) increases Increases the height (h) of the storage rim, increases the internal circulation flow and / or reduces the grinding bowl speed (n _s ).

7. The method according to any one of claims 1 to 6,

characterized,

in that the feed mass flow (rh _m , in) is increased in order to increase the throughput, whereby the grinding bowl rotational speed (n _s ) is increased in order to maintain a grinding bed height (s).

8. The method according to any one of claims 1 to 7,

characterized,

that the roller mill (30) when starting with a higher contact pressure (F _w ) of the grinding rollers (31) than the operating force selected during operation (F _w ) is operated.

9. The method according to any one of claims 1 to 8,

characterized,

that the rotation of the grinding rollers (31) is monitored in operation, and that the pressing force (F _w ) of the grinding rollers (31) is at least temporarily increased if too little rotation of the grinding rollers (31) is detected.

10. The method according to any one of claims 1 to 9,

characterized,

wherein the roller mill (30) is operated in an overflow and / or airflow mode.

11. The method according to any one of claims 1 to 10,

characterized,

that as a material concrete fracture of gravel, sand and cement stone is abandoned, and

that gravel and sand are separated from each other and cement stone by means of the in-bed attrition.

12. The method according to claim 11,

characterized,

that a vertical roller mill with separator (34) is used, a process air stream is adjusted such that cement paste and at least partially cement stone and sand compounds are transported from the overflow mill base to the classifier (34) by means of the process air stream and that gravel and sand are withdrawn as coarse material from the milling process, that at the classifier (34) crushed cement stone is removed as a fine material from the grinding process and cement stone and compounds of cement and sand from the classifier (34) rejected and fed back to the grinding bowl (32), and

that sand is separated from the coarse material withdrawn by sieves.

13. Vertical roller mill

with a rotatable grinding bowl (32) on which a grinding bed (41) of regrind (42) is formed during operation,

with at least two stationary, rotatable grinding rollers (31) which roll on the grinding bed (41) during operation,

with a classifier (34) arranged above the grinding rolls (31), and with a device for defining and maintaining a minimum grinding gap between the grinding bowl (32) and grinding rolls (31).

14. vertical roller mill according to claim 13,

characterized,

in that a hydraulic system is provided for adjusting the contact force (F _w ) of the grinding rollers (31) in operation, which counteracts the weight of the grinding rollers to a surface pressure in the range of 15 kN / m ² to 140 kN / m ² relative to the vertically projected To allow area of the mean roll diameter.

15. Vertical roller mill according to claim 13 or 14,

characterized,

a monitoring system (46) is provided on each grinding roller (31) for monitoring the rotation of the grinding roller (31) during operation.