EP3215272B1 - Method for manufacturing aggregates separated in fractions of different grain sizes - Google Patents

Description

The invention relates to a process for the production of aggregates with isometric grain shapes separated into fractions of different grain sizes. The invention further relates to a system suitable for carrying out such a method.

The term "aggregate" is a granular material that can be used for the production of concrete, asphalt or other base layers. Aggregates can be based on natural or broken shapes. In the latter, large rocks are industrially broken, thereby producing aggregates with the desired grain sizes.

In the case of broken aggregates, depending on the grain size, a distinction is made between stone powder with a grain size of up to 0.063 mm, into fine aggregates, also referred to as "(crushing) sand", with a grain size of> 0.063 mm to 2 mm (asphalt application), 4 mm (concrete application) or 6.3 mm (other covering applications) and in coarse aggregates. The coarse aggregates include split with a grain size above the corresponding upper limit for crushed sand and up to 32 mm, crushed stone with a grain size of> 32 mm to 64 mm and crap with a grain size> 64 mm. Further sub-fractions can be provided within these basic fractions.

It is known that for certain applications, for example as a base course material in road construction or as an aggregate for concrete, so-called isometric, ie geometrically as uniform as possible, grain shapes of the aggregates are more advantageous than so-called anisotropic, ie non-isometric grain shapes. Isometric aggregates can, among other things, have an advantageous effect on the processing properties and on the achievement of high final strengths in building materials. Compared to naturally shaped aggregates have broken aggregates to a relevant extent on fracture edges and surfaces.

For coarse aggregates, an assessment of the grain shape is usually attributed to the ratio of grain length (L) to grain thickness (E), the so-called L / E ratio, of the individual grains. An L / E ratio of ≤ 3 has proven to be a useful limit for the construction industry. The content of aggregates with an L / E ratio> 3 is limited by standards, especially DIN EN 933-4. For fine aggregates, other parameters, such as sphericity or roughness, are determined for the individual grains, possibly in addition to the L / B ratio. Different methods (e.g. microscopy, dynamic image analysis) can be used. In general, the closer the grain shapes are to the spherical shape, the higher the quality of the aggregate for the construction industry.

When producing broken aggregates, a fundamental task is to shred a given rock with the lowest possible energy consumption, with the least possible wear and tear and with as little waste product as possible to a product with the highest possible proportion of isometric grains. To solve this task, several crushers with different shredding mechanisms have so far been combined. The different shredding mechanisms are based on different stresses on the material during shredding. In jaw and cone crushers, the material is mainly stressed and in impact crushers by impact and impact in single grain size reduction. These types of stress lead to different grain shapes and different grain size distributions.

Abrasive rocks (e.g. quartzite, gabbro, granite, porphyry and similar hard rocks) are mostly crushed with jaw and cone crushers. However, jaw and cone crushers deliver comminution products with a high proportion of flat, elongated grains (cf. Stark, U .; Müller, A .: Effective methods for measuring grain size and shape. Mineral Processing 45 (2004) No. 6 ). Around In order to obtain high-quality coarse aggregates, these anisotropic grains have to be sieved off. A significant proportion of the total processed rock is an inferior product in the form of flat, elongated grains in the fine and coarse range, which cannot be marketed or can only be marketed at low prices.

In order to reduce the amount of inferior product, a vertical impact crusher is often used as a so-called "cubicizer" for the flat, elongated grains in order to obtain finished products with higher proportions of isometric grains. It is known that the impact crushing predominantly produces such isometric grains. However, the additional device increases the specific energy consumption in the production of the aggregates. In addition, several crushing stages (crushers) are necessary for the production of different fractions due to the relatively steep grain size distribution, which further increases energy consumption. The parallel use of many shredding devices also increases the investment requirement.

The Tau plant from NorStone (Norway), which is intended for the production of high-quality quartz diorite aggregates for road construction, consists, for example, of three cone crusher stages and an additional vertical impact crusher stage in a function as a cubic unit. In addition, the third cone crusher stage contains a total of five cone crushers for different grain sizes of the aggregates to be produced. A total of eight crushers (seven cone crushers and one vertical impact crusher) are used in this system (see "Manufactured sand in concrete - effect of particle shape on workability"; COIN project report No. 34 (2011), SINTEF Building and Infrastructure, Norway ).

Horizontal impact crushers can be used to crush medium-hard rocks, such as limestone, dolomite, basalt, etc. They deliver shredding products with high cubicity and thus isometric grain shapes. Disadvantages of this horizontal impact crusher are high costs for wear materials and limited availability due to the maintenance that is required relatively often. For the production of crushed sand with isometric grain shapes, an additional vertical impact crusher is usually used as a cubic unit as a third or fourth crushing stage, which is followed by two to three crushers, which are required for the production of correspondingly small grain sizes. Disadvantages of such systems are a relatively high energy consumption (additional machines with peripherals) and a high proportion of rock powder after cubing, for which no further use is generally intended as a product and which consequently represents waste.

A process for the production of crushed sand from moist rock material, for example from gravel washing, is known from the EP 1 681 392 A1 known. There, the moist rock is first dried, then crushed in a jaw crusher and finally classified to separate the crushed sand fractions from fine grain. The drying that takes place before the comminution is intended to prevent the coarse moisture initially adhering to the rock from being distributed to the freshly formed particle surfaces during the crushing process and binding the fine grain formed during the comminution.

The production of aggregates in the context of the described methods is based on the principle of so-called single-grain size reduction, in which the feed material is substantially individually loaded in the corresponding breaking device and is thereby broken.

From other shredding applications, such as grinding cement raw meal or cement from cement clinker, so-called material bed shredding is also known, in which the feed material is fed to the shredding device in such a way that it is in the shredding gap, for example the roll gap of a so-called bed or high-pressure roller mill Form of a material bed is present, which leads to the fact that the particles of the feed material are pressed against each other under high pressure and thereby crushed. The comminution product emerging from the material bed roller mill is largely in the form of agglomerates (so-called "slugs") which, however, disagglomerate with comparatively little energy expenditure to let. Compared to the shredding process based on the principle of single grain shredding, the material bed shredding is fundamentally characterized by a high energy efficiency.

The WO 2010/072276 A1 discloses a method and a device for comminuting mineral regrind, in particular raw ore, in which the regrind is first comminuted in a first material bed roller mill, then subjected to a dry agglomeration and then pre-classified in a dryer fabric device, the coarse material originating from this pre-classification into the first Gutbettwalzenmühle is returned while the fine material is fed to a second Gutbettwalzenmühle. The discharge from the second material bed roller mill is fed to a spiral classifier, which divides the discharge into fine and coarse material. This fine material is then fed directly to a sorting system, while the coarse material is further processed in various process steps and in particular crushed.

The DE 33 37 615 A1 describes a method and devices for comminuting and processing mineral raw materials, for example ores, in which the raw materials are broken up in a crusher and then fed to a material bed roller mill in order to further comminute them. The discharge from the material bed roller mill is further processed and partially crushed further by means of a mill. Overall, the process according to the DE 33 37 615 A1 only one finished product is generated in one fraction. So-called head sludge can be separated as part of the further processing of the discharge from the material bed roller mill, but they are discarded.

The DE 195 12 509 A1 discloses a process for comminuting ore material, which is pre-comminuted in an oxyacetylene mill and then separated into fine and coarse material in a classifying device, the coarse material then being fed to a material bed roller mill. The material originating from the material bed roller mill can then be further classified, it being provided that to recirculate corresponding coarse material in each case. As a result, only a fraction serving as finished goods is generated here.

The DE 37 19 251 A1 describes a process for the continuous pressure comminution of brittle regrind, for example from cement clinker to finished cement, in which the regrind is first fed to a first high-pressure roller press and immediately afterwards to a second high-pressure roller press. The material then passes into a deagglomerator and then into a classifier, the fine fraction emerging from it representing the finished product, while the coarse fraction is returned to the first high-pressure roller press.

Based on this prior art, the object of the invention was to provide a possibility of producing high-quality aggregates with isometric grain shapes from particularly hard and medium-hard rocks. At the same time, the greatest possible reduction in the dust (rock powder) produced during production, the lowest possible energy consumption for carrying out the process and the lowest possible wear on the system used for this purpose should be achieved.

This object is achieved by a method according to claim 1. A system suitable for carrying out such a method is the subject of claim 9. Advantageous embodiments of the method according to the invention and advantageous refinements of the system according to the invention are subjects of the respective dependent claims and result from the following description of the invention.

The invention is based on the knowledge that when using the basically known material bed comminution, a comminution product with, on the one hand, a broad grain size distribution and, on the other hand, with a very high proportion (often around 98%) of isometric grain shapes both in the coarse and fine range are produced can. Since the material bed shredding is also different from shredding processes based on single grain shredding Characterized by a high energy efficiency, the basic idea of the invention is to use the material bed comminution advantageously for the production of aggregates with isometric grain shapes.

Accordingly, a method according to the invention, which is used for the production of aggregates from rocks which are used as finished products and separated into fractions of different grain sizes, is characterized in that the rocks are initially broken up (in particular by means of individual size reduction), then at least partly further broken down by means of a material bed size reduction and thereon then classified to separate the different fractions of the aggregates. It is provided that a pressure of at most 7.5 MPa (75 bar), preferably of between 0.5 MPa and 5 MPa (5 bar and 50 bar) and particularly preferably of between 1 MPa and 3, is provided for the further crushing by means of the material bed comminution MPa (10 bar and 30 bar) is generated in the material bed. This pressure range is sufficient to reliably achieve the desired breaking of the rocks, but at the same time not too high, thereby avoiding further damage to the aggregates, in particular cracks in the grains. It should be emphasized that this pressure range is significantly below the pressure generated in the known applications of material bed crushing for grinding, for example, cement or raw cement flour (over 50 MPa (500 bar) and generally between 100 MPa and 300 MPa (1000 bar and 3000 bar)) lies.

A system according to the invention, which is suitable for carrying out such a method, comprises at least one crushing device (as a primary crusher), a material bed comminution device arranged downstream of the crushing device (with regard to the direction of transport of the material flow through the system), which is suitable for crushing by means of material bed comminution at a pressure of at most 7.5 MPa (75 bar) preferably of between 0.5 MPa and 5 MPa (5 bar and 50 bar) and particularly preferably of between 1 MPa and 3 MPa (10 bar and 30 bar) in the material bed, one sorting device downstream of the material bed comminution device and several the classifying device downstream storage places for the separate storage of the fractions of the aggregates.

According to the invention, the concretization of the aggregates as "finished products" means that they are not further processed (in particular further comminuted), at least within the scope of the method according to the invention or a method in which the method according to the invention represents a process section. In particular, it is provided that no further processing is provided for the finished product aggregates, and consequently they can be used directly as, for example, aggregates for asphalt, concrete or similar building materials.

By further breaking up in the course of comminution of the bed, aggregates with a high proportion of isometric grain shapes are advantageously produced. According to the invention, grain shapes which correspond to defined geometric specifications are regarded as "isometric". In particular, it can be provided that grain shapes whose ratio of grain length (L) to grain thickness (E) according to DIN EN 933-4 is less than 3 (L / E ratio ≤ 3) can be regarded as isometric. The "grain length" represents the largest dimension of the respective grain, defined by the greatest distance from two planes lying parallel to each other tangentially to the grain surface, and the "grain thickness" represents the smallest dimension of the respective grain, defined by the smallest distance of two in each case planes lying parallel to each other, tangential to the grain surface. If necessary, an L / E ratio ≤ 3 can also be provided to define isometric grain shapes (only) for coarse aggregates with grain sizes> 2 mm,> 4 mm or> 6.3 mm to be provided, while fine stone coronations with grain sizes less than or equal to the selected limit value (exclusively or additionally) are defined as non-isometric with reference to a sphericity parameter.

According to the invention, the “grain size” is understood to be the greatest distance from two planes which are each tangent to the grain surface and are parallel to one another.

Due to the wide grain size distribution and the cubic effect of the material bed shredding, compared to conventional systems for production broken crushed aggregates several crushing stages and thus a corresponding number of machines can be replaced by the material bed comminution according to the invention. As a result, both the capital expenditure and the energy expenditure for the operation of a system according to the invention are significantly lower than for a conventional system.

In conventional crushers, the grain size of the aggregate to be produced is usually only set for one fraction via the gap between the jaws of the (jaw) crusher or the distance between the crusher cone and the static crusher jacket (in the case of a cone crusher). By contrast, a material bed comminution device allows a flexible adaptation of the crushing parameters for several fractions of the comminution product to the specific material properties of the feed material and the desired product properties of the comminution product and to the material throughput by changing the grinding pressure, the roller speed and the grinding gap. For example, to produce fine aggregates, the pressure in the mill splitter can be increased. A change in the operating conditions can therefore be used to adapt and, in particular, dynamically change the grain distribution of the products.

Another advantage of the use of a material bed comminution according to the invention for further breaking of the rocks is the relatively low wear on the rollers or rollers of the material bed comminution device used for this purpose in comparison to the wear in the case of a single grain comminution in, for example, a jaw or cone crusher. This ensures a correspondingly long service life for the material bed comminution device and lower expenditure for spare parts.

In a preferred embodiment of the method according to the invention it can be provided that the rocks are broken up by means of the material bed comminution and consequently no more crushing process follows the material bed comminution. This is due to the wide grain size distribution and the high Share (often around 98%) of isometric grain shapes in the comminution product of the material bed comminution is made possible. Further processing subsequent to the comminution of the material bed, and in particular further crushing, is therefore generally not required for the use of the aggregates as finished products.

It can preferably be provided in the context of the method according to the invention that the rocks up to a rock size (greatest distance from two planes which are respectively tangential to the rock surface and parallel to one another) of at most 400 mm, preferably between 50 mm and 350 mm and particularly preferably between 100 mm and 200 mm are pre-broken. This can represent an advantageous size range for the rocks serving as feed material for the comminution of the bed. In particular, this allows the rocks to be broken further in a single comminution pass as part of the material bed comminution up to the maximum grain sizes provided for the finished product aggregates. The maximum grain size provided can be, for example, approximately 32 mm.

A first of the at least two fractions of the aggregates can preferably comprise grains with a maximum grain size of 4 mm, while a second of the fractions can comprise grains with a grain size of> 4 mm to preferably approximately 32 mm. The production of further fractions, in particular sub-fractions, within the two previously defined (main) fractions is possible within the scope of the method according to the invention.

The further breaking of the rocks as part of the comminution of the material bed can lead to the formation of agglomerates comprising the aggregates. Within the scope of the method according to the invention, it can therefore be provided that the aggregates are deagglomerated after further breaking by means of the material bed comminution and before classification. For this purpose, the system according to the invention can comprise a deagglomeration device, for example in the form of a drum deagglomerator that is known in principle. If necessary, the Classifying device and the deagglomeration device can also be integrally formed. For example, moving sieve devices (vibrating sieves) are suitable for both deagglomeration and classification.

In a further preferred embodiment of the method according to the invention, it can also be provided that the rocks are dried, in particular when crushing further by means of material bed comminution. For this purpose, the system according to the invention can comprise a drying device.

It can also be provided that at least some of the rocks and / or aggregates are washed, in particular after classification. As a result, in particular rock powder can be detached and removed from the stones or grains of the aggregates. The system according to the invention can comprise a corresponding washing device for washing. In a configuration of the washing device as a washing drum which is known in principle, the preferably provided process steps of deagglomeration and washing can advantageously be carried out simultaneously and / or in a single device.

Even after the rocks have been crushed, the feed material for the material bed comminution may contain constituents which advantageously should not yet be processed or should no longer be processed as part of the material bed comminution. These constituents can in particular be rocks whose rock sizes are still above a defined maximum value for the feed material for comminution of the bed. Furthermore, these constituents can be grains whose grain size is already smaller than the maximum grain size provided for the finished products and which may also already have an isometric grain shape. Advantageously, it can then be provided that the pre-broken rocks are pre-classified in the material bed before further breaking, in order to filter out corresponding rocks or grains from the feed material for the material bed comminution. Rocks that have been filtered out can be broken up again in the crushing device. Filtered out Grains can be used directly as a finished product, which means that the quantity of feed material can be reduced as much as possible, which can have a positive effect on the energy consumption in the context of material bed crushing. For this purpose, the system according to the invention can comprise a corresponding pre-classifying device.

A material bed roller mill (also called a high-pressure roller press) or vertical roller mill can advantageously be used as the material bed comminution device of the system according to the invention. The classifying device of the system according to the invention can preferably comprise a screening device and / or a classifier, in particular a vortex and / or cross-flow classifier. The breaking device can furthermore preferably be designed as an impact crusher, jaw crusher, hammer crusher or cone crusher. Combinations of these can also be used in the case of several crushing devices.

The method according to the invention is advantageously for the production of aggregates in fractions with different grain sizes from natural mineral rocks, for example limestone, dolomite, basalt, quartzite, gabbro, granite, porphyry, and / or gravel, from slags from iron or steel production and / or made of old concrete.

The use of indefinite articles ("an", "an", "an", etc.), in particular in the claims and in the explanatory part of the description, is to be understood as such and not as the use of numerals. This use is to be understood in such a way that the elements marked with it are present at least once and can be present several times.

Fig. 1:

in einem Diagramm Plattigkeitskennzahlen von Gesteinskörnungen einer Korngrößen zwischen 4 mm und 16 mm umfassenden Fraktion, die durch separate Gutbettzerkleinerung aus Quarzit, Kalkstein und Basalt bei unterschiedlichen Verfahrensparametern gebrochenen wurden;

Fig. 2:

Kornformkennzahlen für die Quarzit-Gesteinskörnungen gemäß der Fig. 1 im Vergleich zu dem Quarzit-Aufgabegut;

Fig. 3:

Kornformkennzahlen für die Kalkstein-Gesteinskörnungen gemäß der Fig. 1 im Vergleich zu dem Kalkstein-Aufgabegut;

Fig. 4:

Kornformkennzahlen für die Basalt-Gesteinskörnungen gemäß der Fig. 1 im Vergleich zu dem Basalt-Aufgabegut;

Fig. 5:

die L/E-Verhältnisse für vier Fraktionen feiner Gesteinskörnungen, die durch Gutbettzerkleinerung aus Kalkstein-Gesteinen hergestellt wurden, im Vergleich zu den entsprechenden L/E-Verhältnissen von Natursand;

Fig. 6:

die Sphärizitätskennwerte für die vier Fraktionen gemäß der Fig. 5 im Vergleich zu den entsprechenden Sphärizitätskennwerten von Natursand; und

Fig. 7:

in einer schematischen Darstellung eine erfindungsgemäße Anlage zur Herstellung von Gesteinskörnungen in Fraktionen unterschiedlicher Korngrößen.

The invention is explained in more detail below on the basis of exemplary embodiments illustrated in the drawings. In the drawings:

Fig. 1:

in a diagram, the flatness parameters of aggregates with a grain size between 4 mm and 16 mm, which are represented by separate material bed crushing from quartzite, limestone and basalt were broken using different process parameters;

Fig. 2:

Grain shape indicators for the quartzite aggregates according to Fig. 1 compared to the quartzite feed;

Fig. 3:

Grain shape indicators for the limestone aggregates according to Fig. 1 compared to the limestone feed;

Fig. 4:

Grain shape indicators for the basalt aggregates according to the Fig. 1 compared to the basalt feed;

Fig. 5:

the L / E ratios for four fractions of fine aggregates, which were made from limestone rocks by comminution, compared to the corresponding L / E ratios of natural sand;

Fig. 6:

the sphericity parameters for the four fractions according to the Fig. 5 compared to the corresponding sphericity values of natural sand; and

Fig. 7:

a schematic representation of a plant according to the invention for the production of aggregates in fractions of different grain sizes.

The 1 to 6 show in diagrams results of tests in which pre-broken rocks made of quartzite, limestone and basalt were broken up separately in a material bed roller mill under different operating conditions to form aggregates.

In the Fig. 1 the flatness indicators of the respective fractions of the aggregates of quartzite, limestone and basalt, which comprise grain sizes between 4 mm and 16 mm, are shown. The non-patterned bars in the diagrams indicate operation of the material bed roller mill with a circumferential speed of the rotating driven roller of approximately 0.2 m / s and a pressure in the material bed of approx. 1 MPa (10 bar), the hatched bars on the left a circumferential speed of approx. 0.2 m / s and a pressure of approx. 3 MPa (30 bar), the hatched bars on the circumferential speed of approx 0.2 m / s and a pressure of approx. 5 MPa (50 bar) and the cross-hatched bars a peripheral speed of approx. 0.9 m / s and a pressure of approx. 3 MPa (30 bar). The flatness figures were determined in accordance with DIN EN 933-3. The aggregates are classified in the best category FI 10 according to DIN EN 933-3 with regard to the content of flat grains, according to which the content of flat grains in these comminution products is below 10%.

In the 2 to 4 are the grain shape indicators of different fractions of the aggregates of quartzite broken by the material bed roller press under the different operating conditions (cf. Fig. 2 ), Limestone (cf. Fig. 3 ) and basalt (cf. Fig. 4 ) compared to the grain shape key figures of the associated feed materials (rocks pre-broken using a jaw crusher). The non-patterned bars in the diagrams indicate the respective mean values for the grain shape indicators from all associated fractions, the left-hatched bars the grain sizes of 4 mm to 8 mm fractions, the right-hatched bars the grain sizes of 8 mm to 16 mm and the fractions cross-hatched bars the grain sizes from 16 mm to 32 mm fractions. The grain shape indicators were determined in accordance with DIN EN 933-4. It can be seen that the content of non-isometric grains in these aggregates is always (clearly) below 10% and thus far below the corresponding value for the associated feed material.

In the Fig. 5 L / E ratios of four different fractions of fine aggregates (crushed sand) broken by material bed crushing are shown. The determined values for the four fractions (grain sizes from 0.063 mm to 0.2 mm, from 0.2 mm to 1 mm, from 1 mm to 2 mm and from 2 mm to 4 mm) are connected with each other by straight lines in order to create a course to visualize. Also shown are the L / E ratios of fractions of natural sand (Rhine sand) corresponding to the first three fractions of the crushed sand. The Fig. 6 shows a corresponding comparison of the sphericity parameters. It can be seen that L / E ratios and sphericity values can be achieved by comminuting the bed, which are comparable to those of naturally rounded natural sand.

The Fig. 7 shows a schematic representation of a plant according to the invention for the production of aggregates serving as finished products in fractions of different grain sizes and the process carried out thereby. Rocks that can come directly from a quarry are transported to a crushing device 2 by means of, for example, a truck 1. The rocks are pre-crushed in the crushing device 2 in order to produce a feed material for a material bed comminution device 3 arranged downstream of the crushing device 2 (here in the form of a material bed roller mill). A pre-classifying device 4 is arranged between the crushing device 2 and the material bed comminuting device 3, by means of which the comminuting product originating from the crushing device 2 is pre-classified (for example by means of a sieving process) in order to remove rocks whose rock sizes are above a defined limit value (for example 200 mm) to separate, whose rock sizes are below this limit (or correspond to this limit). The relatively large rocks are then returned to the crushing device 2 in order to further reduce them, while the relatively small rocks are fed to the material bed crushing device 3 as feed material. The rocks are broken further by means of the material bed comminution device 3, and aggregates with largely isometric grain shapes and different grain sizes are produced in the process.

In a classifying device 5 arranged downstream of the material bed comminution device 3, the rocks are classified into a total of four fractions which differ by different grain size ranges. For example, the classifying device 5 can be designed as a multiple sieve device with a plurality of sieve layers arranged one above the other with a mesh size that decreases from top to bottom.

A first fraction of the aggregates remains in the top screen covering as the screen overflow, the grain sizes of which are still above a defined maximum value for the aggregates provided as finished products. This first fraction is returned to the material bed comminution device 3 in order to be broken up again.

A second fraction of the (coarse) aggregates remains in the middle screen covering as the screen overflow, the grain sizes of which lie within a first grain size range. This first grain size range lies between the defined maximum value and a first mean value for the grain size. This second fraction is stored as a first finished product from a coarse stone crown at a first storage location 6.

A third fraction of the aggregates remains in the lower sieve covering as the sieve overflow, the grain sizes of which lie within a second grain size range. This second grain size range lies between the first mean value and a minimum value for the grain size of the coarse aggregates. This third fraction is stored as a second finished product from a coarse aggregate at a second storage location 7.

A fourth fraction of the aggregates, the particle sizes of which lie below the minimum value for the particle size of the coarse aggregates, is obtained as the sieve passage of the entire multiple-sieve device. This third fraction is stored as a finished product from a fine aggregate (crushed sand) at a third storage location 8.

Instead of a single breaking device 2 serving as a primary crusher for the material bed comminution device 3, several breaking devices 2 connected in series can also be provided. This allows in particular a gradual breaking of the rocks delivered from the quarry until the limit of the grain size provided for the feed material for the material bed comminution device 3 is reached. In this case, a crushing device 2 first passed through by the rocks can be used as a jaw crusher, for example and an adjoining breaking device 2 can be designed, for example, as a cone crusher.

The in the Fig. 7 The system shown can optionally include further components (shown in dashed lines). For example, a deagglomeration device 9 can be arranged between the material bed comminution device 3 and the classifying device 5, by means of which agglomerations that arise during the product bed comminution are deagglomerated. Furthermore, a washing device 10 can also be provided, for example likewise between the material bed comminution device 3 and the classifying device 5, by means of which rock powder can be washed out of the comminution product of the material bed comminution device 3. The deagglomeration device 9 and the washing device 10 can also be integrally formed in one device (for example a washing drum).

Furthermore, a drying device can be provided, by means of which the rocks and / or aggregates are dried, for example during further breaking in the material bed comminution device. This can be done using hot air, for example. For this purpose, the drying device can be integrated in the material bed comminution device 3.

A device 11 for removing buildup (eg mud) from the delivered rocks can also be connected upstream of the breaking device or devices 2. This device 11 can be designed, for example, in the form of a coarse sieve.

Reference number:

1.

Trucks

2nd

Breaking device

3rd

Good bed shredding device

4th

Preclassifier

5.

Classifier

6.

first storage place

7.

second storage place

8th.

third storage bin

9.

Disagglomeration device

10th

Washing device

11.

Adhesion removal device

Claims (15)

1. Method for producing aggregates from rocks, said aggregates serving as finished products and being separated into fractions of different grain sizes, wherein the rocks are first of all precrushed, then at least partly further crushed by means of a material-bed comminution and subsequently classified, characterized in that, for crushing by means of the material-bed comminution, a pressure of at most 7.5 MPa (75 bar) is generated in the material bed.
2. Method according to Claim 1, characterized in that the rocks are finish-crushed by means of the material-bed comminution.
3. Method according to Claim 1 or 2, characterized in that for crushing by means of the material-bed comminution, a pressure of between 0.5 MPa and 5 MPa (5 bar and 50 bar) and preferably of between 1 MPa and 3 MPa (10 bar and 30 bar) is generated in the material bed.
4. Method according to one of the preceding claims, characterized in that the rocks are precrushed to a size of at most 400 mm, preferably between 50 mm and 350 mm and particularly preferably between 100 mm and 200 mm.
5. Method according to one of the preceding claims, characterized in that the rocks are deagglomerated after the further crushing by means of the material-bed comminution and before the classification.
6. Method according to one of the preceding claims, characterized in that the rocks are dried during the further crushing by means of the material-bed comminution.
7. Method according to one of the preceding claims, characterized in that at least some of the rocks and/or aggregates are washed.
8. Method according to one of the preceding claims, characterized in that the precrushed rocks are preclassified before the further crushing in the material bed.
9. Installation for carrying out a method according to one of the preceding claims having a crushing device (2), a material-bed comminution device (3) which is arranged downstream of the crushing device (2) and which is configured for crushing by means of material-bed comminution at a pressure of at most 7.5 MPa (75 bar) in the material bed, a classifying device (5) arranged downstream of the material-bed comminution device (3), and storage places (6, 7, 8) arranged downstream of the classifying device (5) for the separate storage of the fractions of the aggregates.
10. Installation according to Claim 9, characterized in that the material-bed comminution device (3) takes the form of a material-bed roller mill or of a vertical roller mill.
11. Installation according to Claim 9 or 10, characterized by a deagglomerating device (9).
12. Installation according to one of Claims 9 to 11, characterized by a drying device.
13. Installation according to one of Claims 9 to 12, characterized by a washing device (10).
14. Installation according to one of Claims 9 to 13, characterized by a preclassifying device (4).
15. Use of a method according to one of Claims 1 to 8 and/or of an installation according to one of Claims 9 to 14 for producing aggregates, which are separated into fractions of different grain sizes, from natural mineral rocks, from slags from iron or steel production and/or from old concrete.

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