Tank conveyor
A tank conveyor (also called chain scraper conveyor , scraper chain conveyor or, colloquially, a tank ) is a conveyor ( continuous conveyor ) in mining . It is mainly used as a mining aid in hard coal face . The chain conveyor replaced the shaking chute in mining from 1950 .
construction
The armored conveyor consists of several composite sheet steel channels, the armored channels. In the sheet steel channels there are specially shaped drivers which, depending on the type, are connected to one another with one or two chains. The tank drives are located at the ends of the tank.
Armored channel
The armored channel is the main element in the armored conveyor. It consists of rectangular cut sheet steel, the dimensions vary depending on the type of channel. These sheet steel plates are welded to rolled sigma-shaped side profiles that have the same material thickness as the base plate. The side profiles are shaped differently depending on the type of tank. This design gives the armored channel an upper and a lower run . The individual channels can be assembled into a channel run, the length of the channel run is variable. The channels are screwed to recesses in the side profile or plugged together using bolts. The connections allow the individual troughs to be pivoted among one another by around four to five degrees, both in the horizontal and in the vertical direction. This is necessary in order to adapt the channel run to the different lying conditions. In addition to the normal armored channels, there are also pass channels with which it is possible to adapt the length of the armor to the local conditions. This is necessary to get the correct position for the drop point. For the transition between normal channels and the drive station, there are special connection channels in order to gradually adapt the transition from the drive to the channel run.
Bracken
The brackets are attachment plates attached to the side profiles. These plates enable the tank to be loaded more heavily and prevent it from overflowing and thus from conveying losses. There are usually devices on the brackets that enable the protected installation of electrical cables and compressed air or water hoses. Brackets are only attached to the side facing away from the coal face.
Carrier
The carriers of the tank conveyor intervene in the conveyed goods. There are carriers with one and two chains. The drivers with double chain have the option of attaching the chain on the outside or in the middle of the driver. Depending on the number and position of the chains on the carrier, the conveyor is referred to as a single chain conveyor, double center chain conveyor or double outer chain conveyor. For dismantling in an inclined position, there are drivers that are provided with brake flaps. The brake flaps have the task of slowing down the conveyed goods in the upper run.
Curb chain
Armored chains with link thicknesses of 18 millimeters and above are used for double chain conveyors. Today's tank chains have a nominal thickness of 30 millimeters. If the drive power is further increased, even thicker chains must be used. The chains are either connected to the carriers as continuous chains or attached to the carriers as single chain pieces one meter in length with chain locks. So that the chain belt is taut in the tank and does not sag in the lower trough, it is tensioned with a pneumatically or hydraulically operated chain tensioning device. There is also the option of tensioning or releasing the chains using a chain tensioning device. When the conveyor motors are switched off, this takes place via an intervention in the conveyor gear. The chains can be weakened due to wear and tear or corrosion, and the chain can break when the load is subsequently applied. In the event of a chain break, the chain must be put back together at the break using a special chain link, the chain lock.
Drive station
The drive station has a similar structure to the planer drive . The tank drive consists of a machine frame, the gearbox , the clutch, the drive motor and the chain star. Compressed air or three-phase motors are used as drive motors . The drive power for large drives is over 100 kilowatts . Up to four drive motors are required, depending on the length, delivery rate and incidence . Turbo couplings are required as clutches for drives with electric motors, as they facilitate starting and blocking protection. In addition, the clutches compensate for the slight differences in engine speed. In the case of compressed air motors, the motors are connected to the gear unit via an elastic pin coupling. The reasons for this are the soft start-up properties of the air motors. The gears for chain scraper conveyors are compact, they can transmit high power and torques with a smaller volume. As a result, these gears must be well lubricated and cooled. Gearboxes with air or water cooling are used depending on the performance. The gears are lubricated by means of oil lubrication. In particular, the cooling equipment and the lubrication of the gears require regular maintenance and have to be checked for leaks more often.
Uses and types
Tank conveyors are used as a means of conveyance in mining and fixture operations. Depending on the intended use, a distinction is made between face tanks, loading tanks and mobile tanks.
Face armor
Heavy chain scraper conveyors are used as face armor, these conveyors are particularly robust. In these heavy tank conveyors, the tank channels have a material thickness of up to 25 millimeters. These channels withstand forces of 13,000 kilonewtons without major deformations. The drives of these armored conveyors have drive powers of 3600 kilowatts (3 * 1200 kW) and are suitable for face lengths of up to 500 meters. Up to 8000 tons per hour can be conveyed. The armored channels of face conveyors have a lateral guide that is used as a track for the shearer loader or for the coal plow . In order to increase the wear resistance of the channel joints in these channels, particularly strong types of steel such. B. Manganese steel used. To combat dust , nozzles for spraying the planing alley can be attached to the grooves of the faceplate.
Loading tanks
Loading tanks serve as intermediate conveyors between the face conveyor and the line conveyor. The armor is provided with mounting plates and can thus convey very large quantities of goods. As a result, the tank loader is able to absorb peaks that occur, for example, when the planer descends. Due to the rotating drivers, the heap of conveyed material is pulled apart at the drop point on the conveyor belt. This results in an even loading of the conveyor belt. In the cargo tank, a can impact roll crusher integrate to mince larger rocks. This is necessary in particular for the further transport of the rock on the belt conveyor and to avoid conveying disruptions due to blockages in the bunker . The loading tank differs from the normal main line tank by a slightly different design. In the case of the loading tank, the drive end is mounted on a rising support frame. The shoring is placed on rollers, making the armor easier to move. A compressed air or three-phase motor mounted in the conveying direction is used for the drive station. Smaller channels are used as armored gutters than in the faceplate.
Curve armor
Curved armor, also called curve conveyor or rolling curve, are used in the area of line curves or in the transition area between the face and the line. These are special constructions of a conveyor. There are curved conveyors that have a fixed curve radius of 90 degrees and are permanently laid. The disadvantage of these conveyors is the fixed radius and the high maintenance costs.
Mobile tanks
Mobile tanks are used as a means of conveyance during mining with continuous miners . These systems consist of support cars and conveyor bridges. In this system, the support carriage serves as a loading and dropping element. At least one conveyor bridge and two support cars are required for a complete system. Like the conveyor bridge, the support carriage is equipped with a chain conveyor. The conveyor bridges are attached to the support car in an articulated manner, so that curves of 90 degrees are also possible. By putting together support cars and conveyor bridges, a system can be built of any length. However, a miner is required as a machine operator for each support car . In addition, an additional support carriage must be used for each additional conveyor bridge. The material flow takes place from the support car to the first conveyor bridge and from there to the next support car. The last support trolley in the entire conveyor chain is equipped with a belt from which the goods are transferred to the conveyor belt of the line conveyor .
Working principle
The drive motors of the drive station move the chain star attached to the drive through their rotary motion. By the rotational movement of the chain star, the curb chain is in the conveying direction by the upper run pulled. The drivers attached to the chain are pulled further in the conveying direction. At the end of the channel run, the chain is again guided over a chain star and into the lower run, also known as the empty run. The conveyed goods are moved by simply pushing them away in the armored channel. The chain speed is between 0.5 and 0.7 meters per second, it can be adapted to the conveying capacity and the respective operating conditions. The conveying capacity of the face conveyor can be increased by increasing the speed of the tank. However, the running speed must be in the correct ratio to the speed of the planer according to the respective planing process .
Individual evidence
- ↑ a b c d e Walter Bischoff , Heinz Bramann, Westfälische Berggewerkschaftskasse Bochum: The small mining dictionary. 7th edition, Verlag Glückauf GmbH, Essen, 1988, ISBN 3-7739-0501-7 .
- ↑ Ernst-Ulrich Reuther: Introduction to mining. 1st edition, Verlag Glückauf GmbH, Essen, 1982, ISBN 3-7739-0390-1 .
- ↑ a b c d e f g Carl Hellmut Fritzsche: Textbook of mining science. First volume, 10th edition, Springer Verlag, Berlin / Göttingen / Heidelberg 1961.
- ^ A b c d e Heinz Kundel: coal production. 6th edition, Verlag Glückauf GmbH, Essen, 1983, ISBN 3-7739-0389-8 .
- ^ Wirtschaftsvereinigung Bergbau eV: The mining manual. 5th edition, Verlag Glückauf GmbH, Essen, 1994, ISBN 3-7739-0567-X .
- ↑ DBT: Innovations for maximum productivity in mining. Online ( Memento of February 21, 2014 in the Internet Archive ) (accessed on August 25, 2011; PDF; 3.2 MB)
- ↑ Curved joint conveyor patent no. DE3825293C2 April 27, 1995 (accessed on September 7, 2011)
- ↑ Eric Drüppel: Development of a concept for the cutting extraction in rock salt. Dissertation 2010, Rheinisch-Westfälische Technische Hochschule Aachen.
