DK166629B1 - PROCEDURES AND PLANTS FOR PREPARING WINTER USE FOR GRAIN MATERIALS USED FOR WINTER USE. - Google Patents

Abstract

The impure granular material which is fed to a feeder bin (4) is metered through a take-off device (5). An adjoining coarse-grain separator (13) is used to remove the coarse-grain impurities by screening. The remaining granular material is introduced to a drier (16), where the granular material is dried and the fine-grained impurities are separated by pneumatic sifting. The purified granular material is passed to a grit silo (31), from where it can be removed. By treating the used granular material and reusing it, environmental pollution is reduced, while, at the same time, less energy is required since the treatment is carried out without the addition of wash water. <IMAGE>

Description

in DK 166629 B1

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a method of reprocessing gravel material used for winter use on pedestrian-driven, at least partially overcrowded and / or snow-covered road areas to protect persons and vehicles from sliding, in particular for reprocessing gravel, which, in its use, has been contaminated with foreign materials and wetted with melt water and other liquids, the gravel material collected after its use being purified from coarse-grained impurities by sieving and then 10 from fine-grained impurities by wind-sieving and dehumidified.

So far, rock salt has been used to a large extent as winter material for winter use, with which it is possible to obtain ideal safe areas for people and vehicles with relatively little expense. However, with the large quantities of 15 sprinkled salt used, a considerable environmental impact is created, which, after the stronger attention to ecological points of view, is significantly opposed. Since then, the use of bedrock gravel, including crushed, edged natural stones with different grain compositions, has increased considerably in winter as a protective graveling agent.

Experience has shown that approx. 2/3 of the amount of gravel used for winter use is left in the spring and then absorbed by the street sweepers. problems with the use of bedding gravel also occur, especially when considerably larger quantities of bedding gravel are used than before. Also, no gravel is available in unlimited quantities, as its breaking causes damage to the landscape. For this reason, consideration has been given as to whether the gravel collected after its use could be reprocessed for further use. In this way, it must be taken into account that the spent gravel contains environmentally harmful contaminants, for example heavy metals, salts, oils and grease.

On the other hand, however, the storage of large quantities of used litter in depots is problematic.

35 Despite these by the exclusive use of unused litter, ie. new gravel, occurring problems, has the reprocessing of used litter gravel, ie. old gravel, not so far able to break through. The reason for this is the relatively high cost of reprocessing in central locations with the usual wet process in the rail industry. In this procedure, the wash water must be passed over a clearing system. Due to the risk of groundwater contamination by toxins contained in the wash water, it can in no case be caused to seep into open deposition areas. In addition, after washing, the gravel must be dried again with a corresponding 10 large energy consumption, so that it remains rice-proof even at low temperatures.

From FR-A-2 578 454, a method for separating a composite mixture of different particles is generally known. To this end, a pivoting device is used, the mixture being conveyed over a first plateau to the edge of a discharge orifice and then conveyed upwards with air by means of an air stream. Depending on the density and / or dimension, the particles in the mixture describe a similar parabolic escape path and land either on another plateau on a suitable landing surface or on the bottom wall of a gutter. This pivoting device is not suitable for separating dusty contaminants from a damp gravel material.

U.S. Patent No. 4,523,988 discloses a process for reprocessing the abrasive grains in a sandblasting sand. In this way, serious contaminants are first excreted and then a drying of the material is carried out and then a wind screening by dust separation. Admittedly, the drying occurs in a drying drum in which the material is strongly rubbed against each other 30 and thus undesirably diminishes to sand-like. This also means that part of the material is removed as stripped dust during wind sifting.

The object of the present invention is to extract a valuable gravel material by reprocessing camel gravel, with the least possible old gravel being lost. Furthermore, the entire reprocessing process must be carried out quickly and cost-effectively.

This object is achieved according to the invention by providing for the drying and wind sifting to separate fine-grained contaminants, a vibrating fluid bed having a drying zone and a wind sifting zone, both zones being supplied with hot air.

The drying in a oscillating fluid bed can be carried out considerably more gently. The material to be dried is subjected to a microcaste movement on a vibrating fluid bed, thereby substantially reducing the degradation of the material. Furthermore, since the heating medium in both the drying zone and in the wind-sifting zone is passed directly through the material to be dried, an intensive heat exchange takes place so that the drying is accelerated.

Through the work-up by a dry process, i.e.

without the supply of wash water, the cost of waste water reprocessing is eliminated, and the cost of gravel drying is also greatly reduced.

If the wet process is used, the washed 20 and pre-irrigated old gravel still contains 15 to 20% by weight of water to be evaporated in the dryer, while in the process according to the invention with depot moist old gravel it contains only a humidity of between 5 and 7% by weight. This means a 60 to 70 percent reduction in energy consumption during the drying.

The purification of the collected gravel material is carried out by the sieving of coarse-grained contaminants and by the sieving of fine-grained contaminants, while at the same time the gravel material is wetted to a final humidity suitable for winter use.

The invention also relates to a plant whose task is to be able to perform the process optimally. This is achieved according to the invention in that for the drying and the wind sieve for separating fine-grained contaminants in the collected gravel material there is provided a dryer with a oscillating fluid bed, in which a drying zone and a wind sieving zone are arranged one after the other. for separating the coarse-grained contaminants in the collected gravel material in front of the dryer, a pivot screen is coupled.

Preferably, the oscillating fluid bed is associated with a control device which, as a control size, uses the exhaust air temperature at the dryer.

The invention will now be described in more detail with reference to the drawing, which shows an embodiment of a plant for reprocessing old gravel used for winter use, and in which fig. 1 schematically shows a plant for reprocessing old gravel, and fig. 2 is a schematic representation of an apparatus for drying the old gravel and for separating fine-grained contaminants after drying by means of wind sieving.

In FIG. 1, with an arrow 1, is shown the transport of the used and collected old gravel, which is delivered to an intermediate depot 2. Delivery is hereby transport vehicles or 20 directly from the street not the machines. From the intermediate depot 2, the old gravel is transported by means of a transport device 3, for example a loading device, to a delivery bunker 4. This is preferably dimensioned so that it can accommodate approximately a supply of material with which the plant can be operated for approx. 30 to 60 minutes. From the delivery bunker 4, the old gravel is delivered by means of a suitable, adjustable delivery device 5, which is, for example, designed as a vibration conveyor suitable for bunker delivery. From the dispensing device 5, the old gravel is supplied by means of a transport means 12 to a separator 13 for the separation of coarse-grained contaminants in the old gravel. This supply can be done directly or as shown in FIG. 1 by means of the transport means 12, for example an inclined conveyor.

The old gravel usually contains approx. 5 to 7 weight-35 percent coarse-grained contaminants. Separator 13 has the task of separating these foreign bodies and gravel parts with a grain size above the grain size of the gravel material, preferably 8 to 10 mm from the old gravel. Particularly suitable for this purpose is a separator 13. Designed as a swing screen, the coarse-grained contaminants are supplied to a container 29, for example a trough container, by means of a suitable transport apparatus 15, for example a sludge.

The old grit, which is cleaned of coarse contaminants, then enters a drying apparatus 16. via a discharge slurry 16. The drying apparatus 16 has the task of drying the depot moistened old gravel with a moisture content of usually 4 to 7% by weight to a final moisture content of maximum 0.5% by weight. so that the worked up gravel will remain rice-resistant even at low temperatures. For the drying, drying device structures suitable for spray drying can be used. For a number of reasons, a dryer apparatus designed as a vibrating fluid bearing dryer is particularly advantageous therewith, since the wind screen for separating fine-grained contaminants can be integrated into the design of the dryer. In addition, a vibration fluid bearing dryer in its outer dimensions is relatively small and can therefore be very easily placed even in tight space conditions, for example on a vehicle.

A vibration fluid bearing dryer differs from a stationary fluid bed dryer in that it is directed into directed vibrations by means of a vibration generator. In this way, in addition to the air flow produced in the dryer, the drying material is further fluidized by the oscillation movement so that difficult fluidizable materials such as, for example, gravel 30 can be dried.

Bedrock gravel should not contain more than 2 percent fine-grained or dusty contaminants, otherwise graveling with this material may cause the impermeable dusting. For these reasons, the dryer 16 is provided with a windscreen zone 17 integrated therein, which will later be explained in detail in connection with FIG. 2. The wind screen DK zone 176629 B1 6 is at the end of a drying zone 18, as the fine-grained contaminants loosen here from the gravel material. The wind screening zone 17 differs substantially from the drying zone 5 18 in that the air velocity corresponds to at least 1.5 times the fall velocity of the largest particles to be removed and the exhaust air vent is designed in such a way that the detached, fine-grained contaminants are torn For this reason, the wind screening zone 17 for draining the dusty windscreen exhaust air is provided with a special exhaust air line 19. Similarly, the drying zone has a special exhaust air line 20. The old gravel thus purified contains at most 0 , 5 to 2 percent dusty contaminants.

At the end of the wind screening zone 17 is provided an outlet 21 from which the cleaned worked up gravel is transferred to a transport device 30 and transported to a gravel silo 31. The gravel silo 31 has a removal device 32, through which the gravel gravel can be taken out for the further distribution.

The dryer 16 is supplied from a hot gas generator 22 with a drying air of a temperature between 200 and 300 ° C. The heat gas generator 22 consists of a combustion chamber 23, a total air blower 25, a primary air blower 26, a storage tank 24 and adjusting means 27 and 28 necessary for the operation of the hot gas generator 22. The hot gas generator 22 can be operated either with liquid, gaseous or solid. fuels.

The dust-filled exhaust air flowing from the windscreen zone 17 and the drying zone 18 in the dryer 16 is conducted via a conduit 29 to a dusting system 6. A exhaust air fan 7 is connected to the cleaning side of the dusting system 6 to prevent or at least keep it from blowing the fan parts. Through a conduit 8, the 35 purified exhaust air is blown into the atmosphere. The dust separated in the dusting system 6 is discharged via a transport means 9, for example a collecting screw, from the dusting system 6 and is supplied to a closed container 10, for example a closed trough container.

In FIG. 2, it is further seen that the two exhaust air lines 19 and 20 end up in a cyclone 33, where the heavier parts of the dusty contaminants are retained and are again returned to the drying zone via a transport means 34, for example a dust skid. The other fine-grained contaminants leave the cyclone 33 and are routed through the conduit 29 to the dusting system 6.

10 At the end of the windscreen zone 17 facing the drier 16, there is an inlet opening 35 through which the contaminated, collected old gravel is introduced into the drying zone 18.

The dryer 16 has a vibration isolation frame 15 36 which is supported via spring elements 37 on a fixed floor surface 39. The machine parts in the wind screening zone 17 and the drying zone 18 form a countermass to the mass of the vibration isolation frame 36 and are connected to the vibration isolation frame 40 by flexible coupling elements 40.

20 On the vibration isolation frame 36 is mounted a vibration generator 41, for example, with rotating, unbalanced weights driven by a drive 42. Between the two zones 17 and 18 and the vibration isolation frame 36 is formed an air chamber 43 for the drying zone 18 and an additional air 25. chamber 44 for the wind sieving zone, from which two chambers the air flows through a bottom 45 into the drying zone 18 and through a further bottom 46 into the wind sieving zone 17.

The intermediate storage of the old gravel 1 in the open repository 2 has the consequence that its moisture during withdrawal from the repository 2 is constantly subjected to strong oscillations. Special regulatory technical measures are required to ensure regular operation. In addition, in addition to the drying air temperature, the continuous gravel quantities are also controlled by automatic control devices 35 47, 48 and 49. These control devices are connected to the adjustment valves 27 and 28 and to the adjustable DK 166629 B1 8 bunker discharge device 5. Hereby the task is to offset long-term fluctuations in supply humidity, while the control of the drying air temperature offsets the short-term fluctuations. As a control size, the dehumidification of the old gravel is not suitable as it can only be difficult to measure continuously.

However, it has been found that the exhaust air temperature from the wind sifting zone 17 is very suitable as replacement control size.

10 As already mentioned, it is possible to use the described plant in a portable design. In FIG. 1, the system is shown on two vehicles 11 and 38, which can be designed as a motor vehicle or as a trailer or semi-trailer. A further option consists in placing 15 a so-called alternating bridge. The switch bridge is easily solvable with the drive frame so that it can be removed at the point of use and the system can be operated on the switch bridge alone. Since the driveable plant can also operate in the vicinity of residential areas, all plant components may be provided in low noise emission design or be provided with additional noise protection devices.

Claims (4)

1. Procedure for reprocessing gravel material used for winter use on pedestrian-driven, at least partially overcrowded and / or snow-covered 5 road areas for the protection of persons and vehicles from slipping, in particular for reprocessing of gravel that use has been contaminated with foreign materials and wetted with melt water and other liquids, the gravel material collected after its use being purified from coarse-grained contaminants by sieving and then by fine-grained contaminants by wind sieving and dehumidification, characterized in that the drying and wind sieving separation of fine-grained contaminants provides an oscillating fluid bed having a drying zone (18) and a wind-sieving zone (17), both zones being supplied with hot air. Process according to claim 1, characterized in that the cleaning of the collected gravel material is carried out in a transportable manner and in different applications. System for carrying out the method according to claim 20 1, characterized in that a drying apparatus (16) having a vibrating fluid bed is arranged for the drying and wind sealing for separating fine-grained contaminants in the collected gravel material. drying zone (18) and a wind sifting zone (17), in which a pivot screen (13) is coupled to separate the coarse-grained contaminants in the collected gravel material in front of the drying apparatus (16). System according to claim 3, characterized in that a dispensing device (5) is provided for dosing the collected gravel material for the drier (16) and a hot gas generator (22) for the drier (16) is provided. to the dispensing device (5), the drier (16) and the hot gas generator (22) are associated with regulating devices (47, 48, 49) in such a way that the amount of gravel material throughput is controlled depending on the exhaust air temperature of the drier (16).