HK1208002B - Method and device for preparing and separating a material from a combined multicomponent system - Google Patents

Description

The invention relates to a process for preparing and separating a material from a connected multi-material system and a vertical roll mill for performing this process.

In Germany, about 80 million tonnes of building waste are produced annually, most of which is concrete aggregate. Concrete and therefore concrete aggregate are mainly composed of gravel, sand and cementite.

In areas where no natural gravel and sand deposits exist, it is desirable to prepare the concrete aggregate in such a way that it can be separated into its individual components. In particular, there is an interest in the recovery of the gravel and/or sand used. However, the essential point is that the gravel and sand are cleaned as completely as possible from the cement stone, as otherwise the concrete thus produced may have lower strengths when such recovered gravel or sand is used to make concrete.

For example, a separator is known from WO 2011/142663 A1 to reduce concrete fracture and, if possible, to recover the individual components of the concrete, but this device cannot achieve the desired purity of the individual recycled components such as gravel and sand or only under particularly favourable conditions.

The Commission has not yet received any comments from the interested parties on the measures taken by the Belgian authorities to implement the measures in question.

In recent years, rolling mills, which are actually pure crushing units, have also been used for processing and separating materials.

The main purpose of this process is to continue to use the mill as the primary milling unit and to reduce the raw materials given, and to achieve separation only as a secondary downstream property. The necessary pressure-driven crushing can only be achieved by this process if the properties of one component to be crushed are such that it is not broken down during milling. This is not possible, however, since the other component is not broken down by the other component. This does not mean that the separation is not possible.

However, such a process cannot be used for the treatment and separation of concrete aggregates, since no ductile materials are present in the concrete aggregate and the mill would crush all the aggregates or components of the aggregate, thus not achieving the desired result, in particular the cleaning and recovery of the gravel.

The purpose of the invention is to specify a process and device which allows the efficient preparation and separation of a material from a connected multiple system in which the components of the multiple system do not exhibit ductile properties.

This problem is solved by a method according to the invention for preparing and separating a material from a connected multi-material system with the characteristics of claim 1 and a vertical roll mill with the characteristics of claim 13.

Beneficial embodiments of the invention are given in the subclaims and description.

The method of the invention for preparing and separating a compound system of at least one first component and a second component which is connected to the first component, and where both components do not have ductile properties, is to abandon the material of a mill comprising a grinding plate and milling mills for in-bed attrition as a workpiece.

In the case of in-bed attrition, the material is separated into the first and second component by shear application and abrasion of the particles of the components, with the particles of the first component, the particles of the second component and particles of the same component being mutually attracted.

In order to allow in-bed attrition in the rolling mill, the rolling mill is operated with a very low compressive force of the rollers, so that a surface compress only in the range of 15 kN/m2 to a maximum of 140 kN/m2 is achieved relative to the vertically projected area of the medium roll diameter. The compressive force is chosen in such a way that the surface compress does not directly produce essentially any pressure-related separation of the first and/or second components. In other words, the processing of the material takes place essentially only by the attrition of the material or the particles of the first and/or second component respectively.

The mill shall also be operated in such a way that the minimum height of the mill bed is greater than the diameter of the particles of one of the two components.

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According to the invention, it was found that the design of the grinding bed according to the invention with only a very low pressure applied by the rollers in the grinding bed initiates or only allows an attrition process between the individual components of the material, which consists of the combined multi-component system.

The use of the in-bed attrition method of the invention makes it possible to separate multi-material systems with a rolling mill whose components do not have ductile properties. It is even possible to do this separation in multi-material systems whose components are brittle. In other words, no milling takes place in the mill, since the compressive force of the rollers is measured in such a way that no shrinkage is possible by the rollers or their impact directly on the milling bed. The separation and the associated partial shrinkage of the components of the multi-material system are mainly achieved by the attrition process, which takes place in the milling sheet.

For the purposes of the invention, attrition or attrition may be understood as the cleaning of several components from adhesion by friction between them, in particular by the frictional forces on the surfaces which lead to the cleaning of the individual components.

Another basic idea underlying the invention is to design the grinding bed so that it has a minimum height greater than the diameter of the particles of one of the two components. In particular, the harder or harder of the two components of the combined multi-component system is chosen. This design of the grinding bed ensures that the harder component is not crushed by the rolling pressure. In this context, it does not necessarily have to be the hardest of the components. For example, it is also desirable if the grinding bed height is at least as high as the average size of one of the components. This ensures with sufficient probability that the process of crushing the processor does not result in crushing due to the pressure of a roll, but mainly due to the friction of the separation process.

For the purposes of the invention, the compound composite system may also consist of more than the two components exemplified herein, and the harder component may also be understood as the more cohesive component.

The force of compression of the rollers, which may alternatively be called mill rollers, is chosen in such a way that a surface compression occurs in the range of 15 kN/m2 to a maximum of 140 kN/m2. The force of compression depends, among other things, on the size of the rollers, the size of the vertical mill and/or the weight of the rollers. The reference size is the surface compression, so that a guide size is available regardless of the size output of the rollers or mill. The preferred area of surface compression depends on the materials to be processed, whereby the surface compression is not achieved in such a way that there is no significant difference in the size of the crusher.

The invention is based on the surprising finding that, despite the fact that the surface pressing is far too low for the operation of a rolling mill, it is possible to process the finished product. This is mainly because, unlike the previous operation of the mill, no actual grinding takes place, but the materials essentially process each other and are not processed by the rollers. This even makes it possible to process and separate materials with the inventive method, the components of which do not have substantial density differences.

The pressure force is chosen in such a way that the shear forces between the particles produced by in-bed attrition are in the range of 5 kN/m2 to 70 kN/m2, in particular between 7 kN/m2 and 20 kN/m2. The specified ranges of shear forces between the particles of the various components of the combined multi-component system allow good attrition in the grinding bed, so that the preparation and separation of the combined multi-component system can be carried out in the mill. The existing shear forces can also achieve a sufficient purity of the individual components without risking excessive shrinkage.

A component that is essential in adjusting the shear forces is the compressive force of the rollers. This should ideally be adjusted so that the rotation of the milling plate in combination with the rollers and the rotation of the rollers produces the desired shear forces in the milling bed. In other words, different shear or friction forces act on the material to be processed: on the one hand, the shear and friction forces of the individual material particles between each other; on the other hand, the shear forces applied to the material via the rollers.

Normally, when a mill is used as a shredding unit, the rollers are rotated through the grinding bed. In the standard state, therefore, it can be assumed that the rolls' perimeter speed is similar to the relative speed of the grinding bed on the rotating grinding plate. However, if the rollers rotate more slowly than the grinding plate or the grinding plate, the different speeds at the contact points cause shear forces to be generated, which are used for in-bed attrition according to the invention.

More precisely, the shear forces are essentially determined by the speed of the particles being run along the mill underneath, compared with the rolling speed of the roll passing by the particles.

In contrast to the standard operation of milling with a mill, the method of the invention requires a significant increase in the height of the milling bed. For the method of the invention, the milling bed preferably has a maximum height of 8% of the diameter of the milling dish, but preferably about 4% of the diameter of the milling dish. In the conventional operation of a mill, the milling product is actively crushed or crushed by the milling mills. It is desirable that the milling gap, i.e. the distance between the milling mills and the milling machine or the milling bowl, is not too large, so that the milling product is not actively crushed or crushed before it can be moved to another part of the milling machine. However, it is not possible to move the milling product to another part of the milling machine and to the other part of the milling machine.

In contrast, the method of operation of the invention requires that the particles or components of the multi-component system to be attritioned move in the grinding bed. Therefore, it is preferable to have a significantly higher grinding bed height than in rolling mills used exclusively for grinding. The higher grinding bed height results in more relative movements of the particles or components in the grinding bed between themselves, thus achieving in-bed attrition.

In principle, the grinding height can be adjusted by means of the compressive force of the rollers, a load flow rate, a grinding plate speed, a height of a grinding plate bar and/or an internal circulation flow.

An increase in the mass flow, i.e. more flour is fed to the mill per unit of time as the working material, increases the flour bed height. On the other hand, a higher rotation rate of the milling plate in turn decreases the height of the flour bed, since the existing flour is removed from the milling plate more quickly. The staurend of the milling plate is located at the edge of the milling plate and serves to reduce or prevent a flow of flour out over the bowl.

Another parameter that can be used to adjust the grinding height is the internal circulation flow. This is the amount of particles that are rejected during the screening and returned to the grinding plate for further processing. If the internal circulation flow is increased, the grinding height increases. The internal circulation flow can be influenced, for example, by the sights settings as well as by the volume of the process air flow.

For example, when the material binding of the material system is increased, it has been shown to be advantageous to increase the compressive force to achieve the necessary forces for in-bed attrition despite the increased material binding. However, since the ideal is to keep the grinding height the same, other parameters need to be adjusted, since the increased compressive force will first reduce the grinding height. It is preferable to increase the load current and/or internal circulation current. Alternatively or additionally, the number of grinding loads can also be reduced. The setting of this parameter is also in operation, so that, if possible, for example, the test parameter can be determined that the content of the material in the material is higher than the one previously indicated by the Parameter.

Another possibility is to increase the height of the stack, but this is not possible or difficult to do in the course of operation, so that this variation is mainly used when the used mill is to be converted to or designed for another multi-component system.

The material binding of the multi-material system is reduced, the compressive force is reduced accordingly, which would basically increase the grinding bed.

In the operation of a rolling mill, it is generally desirable to process the highest possible throughput, i.e. the maximum amount of material to be processed per unit of time. If the mass flow rate is increased to increase the throughput, it is advantageous to increase the milling speed in particular to maintain the milling bed height. Although an increase in the milling press would also reduce the milling bed height, this would lead to a change in the in-bed attrition variables. In particular, the higher pressing force of the rolls on the milling press, i.e. the force applied by the rollers to the milling bed, would increase the pressure, which can also lead to higher pressures. This can lead to the processing of more material and the separation of the system.It is therefore preferable that when the workpiece flow is increased, this is only compensated by increasing the speed of the milling dish. The same can be done when the internal circulation is increased by force. This is the case, for example, when a higher degree of opening of the materials is required and therefore less material than fine grouts is passed through the screen. This, as already shown, results in more material being returned to the milling machine and thus, in a similar way to increasing the workpiece flow, the milling bed is increased.so that the height of the dining bed remains the same.

There are several types of mills: some are driven directly by the rollers, others, especially the LOESCHE type, are not driven by the rollers themselves but are rotated or rotated by the frictional forces between the rollers and the milling bed. This is relatively unproblematic in the normal operation of a mill, where the mill is used to grind.

In this respect, it is preferable to operate the mill with a higher rolling force than the force chosen in operation when starting up, which is necessary to initially rotate the rollers which have a torque to be overcome.

In this respect, it is preferable to monitor the rotation of the rollers during operation and to increase the compressive force of the rollers at least temporarily if too little rotation of the rollers is detected. Too little rotation of the rollers causes the shear forces introduced into the grinding bed by the rollers to change and thus also the quality of the in-bed friction to change. The short-term increase in the compressive force of the rollers ensures that they have a sufficient rotation or a sufficient torque. For the purposes of the invention, a low speed of the rollers is understood when the rotation of the rolls is less than 50% of the speed of the material flowing through the grinding bed. It is assumed that the speed of the rolls can be adjusted to a lower rate depending on the speed of the grinding material.

To facilitate the starting of the mill, in particular the rotation of the milling rollers, with only low compressive forces permitted for in-bed attrition, the roll bearings are designed with a larger pitch than is usual, which reduces the starting torque and also reduces the risk of the milling rollers staying still or having too low a speed.

In a preferred embodiment, the rolling mill is operated in an overflow and/or air flow mode. In the pure overflow mode, the processed grain is transported, inter alia, by turning the milling bowl over a staurand, which may be present, and falls into an area below the milling bowl. It can be transported from here. In the air flow mode, the grain falling through the milling machine is picked up by a process air stream and, in particular, blown upwards. Above the milling bowl, there is usually a viewfinder to which the processed grain is transported by process air flow. The viewfinder finds a process of processing in which the processed grain is carried out on the milling product, where it is re-processed by means of a fine-grained process.

In the context of the invention, in particular, in-bed attrition is also referred to as a grinding process, as it can be considered as distantly related to standard grinding processes, but differs from them by another crushing technique. However, in-bed attrition is performed by means of a rolling mill, so that the terminology for mills is applied for easier understanding, although in the actual sense no more grinding takes place. In a combined overflow and air flow mode, the process air flow that runs around the grinding bowl does not absorb all of the overflowing grinding material, but only a part of it. Another part falls down and is transported by means of feed from the grinder below the bowl.

In a preferred embodiment, the material to be prepared and separated from the combined composite system is concrete crusher. The concrete crusher itself is usually composed of gravel, sand and cementite. The method of the invention separates and purifies gravel and sand from each other and from the cementite by means of in-bed attrition. In-bed attrition, in particular, abrades the cementite from the gravel and sand, so that gravel and sand are essentially in pure form again after the invention process and can thus be used again for the production of concrete.

In a further advantageous design of the process, a vertical roll mill with a viewfinder, which may also be integrated, is used; in addition, a process air flow is adjusted so that a component, such as cementite, and at least partial compounds from the first and second components, such as cementite and sand, are transported from the overflowing milling material to the viewfinder by the process air flow, while the first purified component, such as gravel and sand, is removed as the raw material from the milling process.

It is also provided that at least part of the crushed second component, such as crushed cementite, is removed from the milling process as finishing material on the screener and that particles of the second component not sufficiently crushed and residues from the first and second components, such as cementite and compounds of cementite and sand, are rejected by the screener and returned to the milling bowl.

A vertical roll mill is designed to operate in a combined overflow and air flow mode. The process air flow, which runs from the bottom around the grinding bowl, is set to carry only light or small materials, especially crushed cementite and cementite and sand particles, upwards towards the visor. Cleaned heavy components such as sand and gravel can fall down against the process flow and be ejected as coarse material from the grinding process. In addition, grown material, also called grown material, can be ejected from the grinding components, and cementite can be ejected as coarse material from the grinding process. This can be detected by means of a sand-based process, which is not yet ready to be detected, as described in the invention.

The material brought to the visor by the process air stream is seen there. Depending on the setting of the visor, for example, only crushed cement stone is ejected as fine matter, while the remaining material is returned to the grinding bowl. The crushing of the cement stone is essentially not by a pressure application but by in-bed attrition according to the invention process.

The method of the invention may be performed preferably by means of a rolling mill with a rotary milling bowl, on which a milling bed of milling material is mounted and which has at least two stationary rotary milling rollers which roll on the milling material in operation, preferably with a viewfinder placed above the milling rollers and in addition with a device to define and maintain a minimum milling gap between the milling bowl and the milling rollers.

The vertical roll mill of the invention is based on the understanding that in-bed attrition requires or may result in significantly less compression of the grinding material on the grinding bed than a conventional grinding bed, such as that used in coal grinding. However, this low compression or force effect by the grinding mills poses a problem due to locally different hardness and other properties of the grinding bed, which may be markedly different. For example, at some points the low compression and relatively high height of the grinding bed may lead to more air pressure induced by the grinding of the grinding material than at other places.

In this respect, the invention recognises that for the first time in vertical milling, it is necessary to provide a device to define and maintain a minimum gap between the grinding plate and the milling rollers, which prevents the milling rollers from passing through the grinding plate due to the different properties of the grinding bed.

There are various ways of designing these devices, for example, in a favourable way of designing the milling mills, the milling mills may have appropriate attachments or buffers, or the hydraulic system of the milling mills may be designed accordingly.

In a preferred embodiment, a hydraulic system is provided to adjust the compressive force of the milling rollers in operation, counteracting the weight of the milling rollers to allow a surface compressive force in the range of 15 kN/m2 to 140 kN/m2 relative to the vertically projected area of the medium roll diameter. Traditionally, the hydraulic system in vertical mills, especially the LOESCHE type, is designed so that the compressive force of the milling rollers is in the same direction as the weight.

The size of the milling rollers in different milling systems and their weight of up to 45 tonnes make it necessary to provide for an inverse hydraulic system to reduce the weight of the milling rollers pressing on the milling bed.

In an advantageous embodiment, a monitoring system is provided on each milling roller to monitor the rotation of the milling rollers during operation. This is necessary when using a vertical mill for in-bed attrition, as the work is carried out with very low compressive force, as already shown, so that the milling rollers may not rotate sufficiently. This condition can be detected and appropriate countermeasures can be initiated by providing monitoring systems, for example by temporarily increasing the compressive force.

The invention is explained in more detail below by means of schematic examples of execution, with reference to the figures shown below: Fig. 1 a flow diagram of an inventive concrete preparation;Fig. 2 a cut through a vertical mill; andFig. 3 a cut of the vertical mill from Fig. 2.

An example of the process of preparation and separation of a material from a compound composite system is shown in Fig. 1 as a flowchart 10 for concrete crushing. The process of preparing concrete crushing described below can be used in the same or similar manner for other material systems in which the individual components do not have ductile properties. The following is merely an example to illustrate the exact execution of the process and its advantages in examples. The individual steps described in this example, which are also described in sequence, can be performed individually and thus each can be considered as part of the invention.

Concrete granules are traditionally produced in fractions of 0 mm to 63 mm from concrete crushing by breaking and separating reinforcing steel. Afterwards, a classification is usually made into gravel and sand fractions. However, these fractions do not yet have negligible adherence of cement stone. Therefore, using recycled gravel and sand of only up to a maximum of 15% as an additive in the production of concrete as a substitute for primary and sand is considered technically feasible.

This limit of up to 15% of recycled material as aggregate of gravel and sand can be significantly increased by the method of the invention.

This is done by using concrete granules up to 80 mm in grain size as starting material or as a break-out product 11 This concrete granulate, also known as concrete crusher, is fed to a mill 12 according to the invention as a break-out material The mill 12 is operated in the combined overflow and air flow mode in the process described in Fig. 1 and is also called a vertical mill The processes in the mill 12 and the operation of the mill 12 will be discussed in more detail later in the section on Fig. 2.

The rolling mill 12 is operated as an in-bed attrition unit and not as a crushing unit according to the invention, so that processed and crushed cement stone 16 can be removed from the processing circuit by a viewfinder provided in the rolling mill 12 which can in principle also be switched off from the rolling mill 12.

The overrun is taken from the processing in the rolling mill 12 of coarse material 13, which consists essentially of processed gravel, sand and still grown material, but the proportion of which is significantly lower than in the finished product 11. The grown material may in particular be gravel and/or sand with cement stone adhesives. The coarse material 13 is then subjected to a sieve 14 which allows the sand 17 to be extracted in a fraction of 0 mm to 2 mm. This sand 17 has been purified by the method 10 of the invention to such an extent that it can be used in the manufacture of concrete similar to primary sand.

The coarse material 13, which is over 2 mm in size, is then subjected to a density sorting 15 to remove cleaned gravel 18 of higher density from the processing cycle. Material which is not sufficiently dense, in particular gravel and/or sand with cementite deposits, is again fed into the in-bed attrition in the mill 12.

The method is also conceivable, but not shown here, to introduce sand into a sealant sorting process to remove any adherence to cement stone or other impurities still present there and re-inject it into the rolling mill process.

The method of the invention 10 thus makes it possible to extract from concrete aggregates, in particular concrete granulate 11, gravel 18 and sand 17, at such a high purity that these components can be used in the production of concrete in a manner analogous to primary aggregates and sand, thus achieving a much higher recycling rate than the 15% rate previously possible.

The waterproofing can be done as dry waterproofing, for example by means of windscreen, air-setters and/or air-spin layer sorting. Alternatively, wet waterproofing can also be carried out. However, the materials fed back to the mill 12 must be dried again. Wet sorting methods include, for example, floating sink separation, both static and dynamic, set sorting, spindle separator or furnace sorting and spin layer sorting.

The rolling mill 12 and its operation for in-bed attrition are described below in more detail with reference to the more detailed Figure 2.

Fig. 2 shows a schematic cross-section of a LOESCHE type vertical mill 30 The main component of the mill 30 are cone-shaped milling rollers 31 which roll on a milling bed 41 The partial cross-section shown here shows only two milling rollers 31 However, vertical mills 30 with three, four, six or more milling rollers can also be used.

The milling plate 41 is mounted on a milling plate 32. The milling rolls 31 themselves, which may alternatively be called rollers, are fixed in place but rotatable around the marked axis. The milling plate 32 in turn is rotatable around its central axis as indicated. Now, when the milling plate 32 is rotated, the milling material 42 present on the milling plate 42 also rotates. This causes the milling rolls to be moved in 31 turns by friction between the milling material 42 and the outer contour of the milling rolls 31.

Above the grinding plate 32 a viewfinder 34 is provided, which can be operated both dynamically and statically.

The item 42 or the aggregate, e.g. concrete, is fed into the processing process via a material input 35 whereby the material input 35 is designed to be fed into the central area of the aggregate bowl 32.

The rotation of the milling bowl 32 accelerates the milling material on the one hand and carries it outwards in a spiral manner on the other, so that it is overturned by the milling rollers 31. However, according to the in-bed attrition method of the invention, the milling rollers 31 are operated in a different way than is normally known in rolling mills 30 and are not used essentially to reduce the milling material's pressure.

According to the method of the invention, the milling rolls 31 apply only a very low surface pressure to the milling bed 41, ranging from 15 kN/m2 to a maximum of 140 kN/m2.

Usually, milling rollers have an average diameter of up to 2.8 m and weigh up to 45 t. This high weight would achieve a much higher surface pressure than the maximum possible in-bed attrition. For this reason, an inverse hydraulic system, not shown in Fig. 2, is provided to counteract the weight of the rollers 31 and can act as a negative force on one of the milling rollers 33's swinging levers 31. In other words, the inverse hydraulic system presses on the pivot axis 33 in such a way that the roller 31 is lifted slightly or that a force acts on the rollers against their weight.

By further giving up new grinding 42 and by turning the grinding plate 32, which may also be called the grinding plate, the material already partly processed on the grinding plate 32 is displaced and passed over a staurand 36 into a gap between the grinding plate 32 and the mill housing.

The operation of the mill in both overflow and air flow modes results in a first inspection at this point, where part of the overflowed processed material is transported by the process air 37 flowing in from below towards the visor 34, while another part can be removed from the machining circuit as overflowed bulk.

The first inspection is based on the amount of process air supplied 37; in addition, inspection can be affected by a blast furnace 38 which, in combination with the blast furnace 38, adjusts the process air 37 to remove 51 mainly gravel and sand from the machining circuit as overflowing coarse material and then screens it as described in Figure 1.

The process of extraction of the material from the aggregate is carried out by a process called "concrete crushing" (see Figure 1).

The process air and the optional shovel crown provide an initial inspection which can be considered as a seal sorting.

The process air 37 is blown in, and carries in particular crushed cementite and particles of sand with adherent cementite to the visor 34, where a second visor is carried out, again a seal sorting.

In this case, the visor 34 is used to remove from the machining circuit in particular the cement stone which has been sufficiently crushed, and this crushed cement stone is removed from the machining circuit with the process air flowing out at the process air exit.

Insufficiently crushed cementite or grown material from cementite and sand is returned to the grinding plate 32 via a 40 degree cone and fed for further in-bed attrition.

In addition, the rollers 31 have a speedometer 46 to measure the speed of the rollers 31 during operation, since the low compressive force applied to the rollers 31 by the in-bed friction may cause the rollers to turn too slowly.

The method of the present invention and the successful in-bed attrition require that the cooking bed be designed to be high enough to allow sufficient particles of the workpiece to be present to allow mutual attrition.

In Figure 3 a section of the mill 30 from Figure 2 is shown, using the same reference marks as in Figure 2.

The main factors for influencing the grinding height s are the load current ṁm,in, the compressive force FW of the grinding rolls 31, the rotation rate of the grinding plate nS, the height h of the stain 36 and the internal flow rate.

The effect of each of the adjustment parameters is explained in more detail below, each assuming that the other parameters remain the same in this context.

In a simple way, the grinding height s can be varied by a variation in the compressive force FW of the rollers 31 which affects the surface compression. In the case of surface compression, this is the force acting directly below the rollers on the grinding bed. If the compressive force FW of the rollers is increased, the grinding product is more compacted or crushed, so that the grinding height s decreases. Conversely, the low grinding height s increases when the rollers 31 are pushed on the grinding bed 41 with a higher compressive force FW.

An increase in the mass flow rate ṁm,in increases the grinding height s. If more material is added to the grinding bowl 32 per unit of time, then, assuming the same time spent on the grinding bowl, there is more grinding on it. This inevitably means that the mass flow rate on the mill ṁm,on is also increased.

The impact on the workpiece flow ṁm,in can be done in two ways: first, the mill can be given 30 more workpieces per unit time, and second, the sight can be adjusted so that there is a higher rejection, i.e. a higher rejection at the sight, so that more material is returned to the milling bowl 32. The rejection can also be increased by increasing the process air flow, since in this case less workpiece is removed from the output circuit as bulk, but instead is transported as fine material to the output circuit. The workpiece flow ṁm, as well as the internal flow, significantly affects the output flow, which in turn increases the output flow. This means that the input flow is increased, so that the output flow is also increased, which means that the input flow is also increased.

Another way of varying the grinding height is to increase the bowl speed nS. If this is increased, the grinding height s decreases. A higher grinding speed nS reduces the residence time of the material to be processed on the grinding bowl 32.

Another way to influence the grinding bed height s is the staurand 36. If its height h is increased, more material accumulates on the grinding plate. This means that there must basically be more material on the grinding plate 32 in order for it to flow out of the grinding plate 32 with the output mass current ṁm.

The main point about all the parameters presented here is that they have an influence on each other. Thus, a higher staurand 36 leads to a higher level of feed, on the one hand, and a longer residence time of the workpiece on the dish, on the other. 32 This leads, depending on the compressive force FW of the rollers 31 to better friction between them, but also to an undesirably long load time and thus to a lower throughput overall.

The present invention is an example of the combination of individual features of the process and the vertical mill of the invention, but it is obvious that these features can also be used separately.

Similarly, the example given in Figures 1 and 2 relates to the treatment of concrete aggregates, but the method of the invention can also be used for the treatment and separation of many different interconnected multi-material systems. For example, in-bed attrition in the rolling mill, which in other words allows only frictional application of the material to be worked and does not constitute actual separation, can also be used for the treatment of natural slate, which consists of clay slate and impurities such as lime, ores or other organic components.

Similarly, the process of processing mica, which consists of layer silicates and possible impurities, is suitable, but this is only because no suitable dry attrition and separation processing methods have been known.

The method of the invention can also be used for the preparation of industrial sands containing kaolin, consisting of kaolin, feldspar and quartz sand. It is also possible to use and prepare graphite tar, which is composed of graphite and earthenware matrix, and clay or bentonite, contaminated by sand or non-layer silicates, and to dissolve heavy mineral sands by attraction to separate binding components and subsequently to separate rutile, zircon, ilmenite, etc., from a non-sandic action by a process similar to the one used for the preparation of the invention. It is possible to obtain even C-Cr-slabs, which decompose, dissolve and become stable under existing sands, but not otherwise. However, since the present invention does not involve a methane component, it is not possible to obtain a composition from other materials, as is the case in the present invention.

The process and the rolling mill of the invention thus make it possible to prepare and separate interconnected multi-material systems in a simple and efficient manner.

Claims (14)

1. Method for preparing and separating a material comprising a composite multi-substance system, wherein the composite multi-substance system consists of at least a first component and a second component which is connected to the first component, and wherein neither of the two components has any ductile properties, wherein the material is fed as feed material (42) to a roller mill (30) with a grinding pan (32) and with grinding rollers (31) for in-bed attrition, wherein a grinding bed (41) comprising material to be processed and material that has been processed is formed on the grinding pan (32) during operation, wherein the grinding rollers (31) roll on the grinding bed (41) during operation, wherein the material is separated during the in-bed attrition by means of the grinding rollers (31) in the grinding bed (41) into the first and the second component through shear stress and abrasion of the particles of the components between themselves, wherein the particles of the first component, the particles of the second component and particles of the same component are reciprocally attrited, wherein for the in-bed attrition the roller mill (30) is operated only with a pressing force (F_W) of the grinding rollers (31) in order to achieve a surface pressure in the range of from 15 kN/m² to 140 kN/m² with respect to the vertically projected area of the average roller diameter, which is selected so that essentially no pressure-based comminution of the first and / or the second component is carried out directly through the surface pressure, wherein the roller mill (30) is operated in such a way that the grinding bed (41) has a minimum height that is greater than the diameter of the particles of one of the two components, and wherein at least the first and the second component are removed from a processing circuit of the roller mill (30) and sorted.
2. Method according to claim 1, characterised in that the pressing force is selected in such a way that the shear forces between the particles produced during the in-bed attrition lie in the range of from 5 kN/m² to 70 kN/m², in particular 7 kN/m² to 20 kN/m².
3. Method according to claim 1 or 2, characterised in that the grinding bed height (s) is controlled to a maximum of 8% of the grinding pan diameter.
4. Method according to one of claims 1 to 3, characterised in that the grinding bed height (s) is controlled to approximately 4% of the grinding pan diameter.
5. Method according to one of claims 1 to 4, characterised in that with a required pressing force (F_W) the grinding bed height (s) is adjusted by means of a feed mass flow (m_m,in), a grinding pan rotational speed (n_s), a height (h) of a retention rim of the grinding pan (31) and / or an inner circulating flow.
6. Method according to one of claims 1 to 4, characterised in that if the material bonding of the multi-substance system is increased the pressing force (F_W) is increased in order to achieve the in-bed attrition, wherein the feed mass flow (m_m,in) is increased, the height (h) of the retention rim is increased, the inner circulating flow is increased and / or the grinding pan rotational speed (n_s) is reduced in order to maintain a grinding bed height (s).
7. Method according to one of claims 1 to 6, characterised in that the feed mass flow (m_m,in) is increased in order to increase the throughput, wherein the grinding pan rotational speed (n_s) is increased in order to maintain a grinding bed height (s).
8. Method according to one of claims 1 to 7, characterised in that the roller mill (30) is operated during start-up with a higher pressing force (F_W) of the grinding rollers (31) than the pressing force (F_W) selected during operation.
9. Method according to one of claims 1 to 8, characterised in that the rotation of the grinding rollers (31) is monitored during operation, and the pressing force (F_W) of the grinding rollers (31) is increased at least over time if a rotation of the grinding rollers (31) that is too low is ascertained.
10. Method according to one of claims 1 to 9, characterised in that the roller mill (30) is operated in an over-running and / or air stream mode.
11. Method according to one of claims 1 to 10, characterised in that crushed concrete comprising grit, sand and cement stone is fed as material, and grit and sand are separated from each other and from cement stone by means of the in-bed attrition.
12. Method according to claim 11, characterised in that a vertical roller mill with a classifier (34) is used, a process air stream is adjusted in such a way that cement stone and at least in part compounds of cement stone and sand from the over-running grinding material are transported by means of the process air stream to the classifier (34), and grit and sand are removed from the grinding process as coarse material, comminuted cement stone is removed from the grinding process as fines at the classifier (34), and cement stone as well as compounds of cement stone and sand are rejected by the classifier (34) and fed back to the grinding pan (32), and sand is separated from the discharged coarse material by means of screening.
13. Vertical roller mill, with a rotatable grinding pan (32), on which a grinding bed (41) of grinding material (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 rollers (31), and with a means for defining and maintaining a minimum grinding gap between the grinding pan (32) and grinding rollers (31), wherein a hydraulic system for adjusting the pressing force (F_W) of the grinding rollers (31) during operation is provided, which counteracts the weight force of the grinding rollers in order to facilitate a surface pressure in the range of from 15 kN/m² to 140 kN/m² with respect to the vertically projected area of the average roller diameter.
14. Vertical roller mill according to claim 13, characterised in that a monitoring system (46) is provided on each grinding roller (31) in order to monitor the rotation of the grinding roller (31) during operation.