Patent Application
20080142767
The invention relates to an retracting apparatus for at least partially retracting from a substantial horizontal shaft a train of parts of a high wall mining apparatus which are located within said shaft. The invention also relates to a method for at least partially retracting from a substantial horizontal shaft a train of parts.
Highwall mining is conducted for removing coal, minerals, ores or other materials from seams or veins under an overburden which may be accessed from an exposed edge of the seam or vein. Highwall mining is applicable where the appropriate machinery can be placed in a cut or bench to extend a cutterhead, followed by a succession of conveyor segments or units as the cutterhead advances, into a substantially horizontal shaft under the overburden. The conveyor segments are also known as push beams, as they are not self-propelled; rather they are as a train (the succession of conveyor segments including the cutterhead) pushed into the mine by a launching device. Each conveyor segment has augers or a conveyor belt to move coal from its lead end to its rear end and further onto the next rearward conveyor segment, and to the launching apparatus, also known as “launch bed”, ultimately. The augers or conveyor belts can be powered by shafts connected from one conveyor segment to the next, ultimately turned by a motor on the launching device or by a motor at the cutter head end of the train.
When a shaft has been mined exhaustively the train of equipment parts in the shaft has to be removed to be used for other shafts. In apparatuses known until now removal takes place by retracting the train from the shaft with the launching apparatus by exerting a pulling force to the conveyor segment adjacent the launching apparatus. By the connection between the conveyor segments the outer segment will pull the train from the shaft. This method work well with trains with a limited length.
Recent developments lead to longer or rather deeper (e.g. over 300 meters) shafts and hence to larger trains. The retracting of such a longer train is increasingly difficult. This forms a limitation (bottle neck) in further optimising highwall mining. The prior art method of pulling the train by pulling from the rearmost conveyor segment leads to breakage of the connections between the couplings between adjacent train segments and/or fixation of the train in a shaft.
In case a connection element is used, the connection element needs a substantial pulling force which is cannot be generated by the launching device without undue modifications. These problems are increased by the demand of mining in steeper downward sloping shafts (e.g. shafts sloping down over 12°).
The aim of the invention is to provide an apparatus and a method which are both suitable for retracting deep wall mining apparatuses from shafts with a higher capacity than the prior art technique, which method and apparatus are thus suitable for longer shafts, a larger number of conveyor segments, for rougher mining conditions and/or for steeper downwardly sloping shafts.
This aim is reached with an apparatus for at least partially retracting from a substantial horizontal shaft a train of parts of a high wall mining apparatus which train of parts is located within said shaft, the apparatus comprising: a connection element connectable to the train of parts, and a pulling device located outside the shaft and connected to the connection element for retracting the connecting element, wherein the pulling device is an individual unit separated from a launching device for the train of parts.
Such an apparatus can retract the train of parts (a cutterhead, followed by a succession of conveyor segments) from the shaft either on its own or in combination with the launching device that was used in excavating the shaft or without help of the launching device. The use on its own allows to optimize the use of the launching device by using the launching device for other purposes at the time the retracting apparatus according the invention is used for the retraction of the train of parts.
Also the retracting apparatus according the invention can be designed for only the purpose of retraction without other requirements to the equipment; this likewise applies for the launching device; the requirements for retraction the train from a shaft are not (or at least less) interfering with the launching requirements to the launching device. This enables an simpler and cheaper construction of the launching device. A further advantage is that existing mining equipment can be used with the improved mining method; only an individual extra apparatus according the invention is required. It is further possible to use the retraction apparatus to successively retract different trains of parts of plural high wall mining apparatuses. Also the retraction apparatus according the invention can be available from stock for specific occasions.
Further it is emphasized that the cooperation between the retraction apparatus according to the invention and the launching device allows an even heavier load of equipment parts to be removed from the shaft. Herein the group of units adjacent to the launch device is retracted by the launch device by exerting a pulling force to the units which are transmitted from one unit to the next unit by the coupling between the units. The units further in the shaft are retracted by the retracting device through the pulling element.
The aim is also reached by a method for at least partially retracting from a substantial horizontal shaft a train of parts of a high wall mining apparatus which are located within said shaft, the method comprising the following steps: arranging a retracting apparatus, comprising a pulling device outside the shaft, connecting the pulling device, a connection element and the train of parts, and retracting the connecting element, wherein the pulling device is arranged separated from a launching device.
According to a preferred embodiment the retracting apparatus comprises at least one supporting element to exert a supporting force against the wall in which the shaft has been excavated. The forces needed to generate a force sufficient to withdraw the cutter head and the conveyor segments from the shaft can be extremely large so that the retracting apparatus can tilt, can slide or even can be pulled into the shaft. The preferred features above avoid these disadvantages with a relatively simple construction that also requires minimal operator attention.
The invention also relates to a method wherein the retracting apparatus comprises at least one supporting element which is arranged adjacent to the wall in which the shaft has been excavated before the pulling device is retracted.
According to another preferred embodiment the connection element is connectable to the train of parts at least one connection position and the intersection of the normal line of the connection position on the face of the wall is within the lines connecting the outer points of the supporting elements. These features lead to a stability during pulling process so that tilting of the apparatus is avoided.
A main advantage of high wall mining is the fact that the shafts need not to entered by humans, so that safety features are limited. Consequently it is not an option for an operator to enter the shaft bringing the connection element into the shaft and attach it to some position of the train, for instance the cutterhead that is the part furthest in the shaft. A preferred embodiment provides a method wherein the connection element is connected to the train of parts before it is inserted into the shaft.
During the functioning of the retracting apparatus according to the invention the conveyor segments appear from the shaft one by one. They have to be removed and stacked or disposed of otherwise. This is a function normally conducted by the launching apparatus. Consequently both the retracting apparatus according to the invention and the known launching apparatus are active simultaneously. To allow these apparatuses to work simultaneously the apparatus according to the invention is adapted to be located substantially sideways of the elongation of the shaft offering the launching device a position in front of the shaft. This allows both apparatuses to be positioned close to the aperture of the shaft so that they can function simultaneously. The manipulation of the components retracted from the shaft however does not require a launching device per se. It is also possible to handle the retracted component without the help of a launching device.
Yet another embodiment provides the feature that the connection element is flexible and that at the connection position a pulley has been located for guiding the connection element from the direction perpendicular to the wall to the retracting apparatus. Although rigid connection elements are not excluded, the advantageous when a flexible connection element is used, as the flexibility allows the connection element to be guided, e.g. along a pulley, form the direction parallel to the shaft to another direction for instance a direction perpendicular thereto. This feature eases the construction of the retracting apparatus when it is to be located sideways of the launching device.
Another advantage of the flexible connection element is the fact that is can be wound on a winch, thus avoiding voluminous apparatuses especially in a non operative situation.
Preferably the supporting elements are connected to the connecting apparatus through a pivotable lever. This lever functions as a compensating lever for uneven forces so that both connection elements bear the load for which they are designed.
When the axis of the pivotable lever coincides with the axis of the pulley which is a further preferred embodiment, forces are restricted within the lever. Consequently no forces are transmitted to the beam.
When all parts of a mining apparatus have been retracted from the shaft, the operation is normally moved to a next shaft. Thus it is advantageous that the retracting apparatus is moveable easily. Such an easy movement of the retracting apparatus can be realized when the pulling device is equipped with a vehicle which is adapted to propel itself.
High wall mining takes place in rough areas. Besides the mining process leads to heaps of coal and mine stone lying around. To make the moving of the retracting apparatus easier, it advantageously comprises tracked wheels and/or caterpillar tracks.
The self propelled retracting apparatus advantageously has an engine. As moving of the retracting apparatus normally will not take place at the same time as the retracting of the parts of the mining apparatus from the shaft, the same engine can be used for both retracting and transportation of the retracting apparatus. This is facilitated when the vehicle comprises an engine coupled with a hydraulic pump and that the winch and the wheels are adapted for hydraulic drive. Due to the fact that under normal conditions the power required to retract the parts from the shaft is lager than the power needed for moving, the engine has to be dimensioned for its retracting duties.
The present invention will be further elucidated with reference to the non-limitative embodiments shown in the following figures, in which:
The invention is related to high wall mining, wherein a launch vehicle 1 is arranged close to a vertical wall 2 of a geological structure 3 in which a mineral, like coal or ore is present. The launch vehicle 1 is adapted to propel a cutter head towards the vertical wall 2 of the geological structure 3. The cutter head digs itself into the geological structure forming a shaft 4 and it ejects the dug out material outside the geological structure 3. To allow further digging into the geological structure 3 conveyor segments 5 are inserted between the cutter head and the launch vehicle. These conveyor segments 5 serve to fill up the distance between the launch vehicle 3 and the cutter head, to transmit drive power for the cutter head from the launch vehicle 3, and to transport the material dug out from the shaft 4 out of the shaft 4. The process thus described is continued under insertion of an increasing number of conveyor segments 5 until a certain length of the shaft 4 is attained.
To use the cutter head and the conveyor segments 5 for the digging of other shafts 4, they will have to retracted. Until recently the retracting was executed by a retracting the conveyor segments with the launch vehicle 1. The trend goes towards deeper shafts 4 requiring more conveyor segments 5 to be inserted into the shaft 4 and hence to retracted from the shaft 4. This requires a large force, not only as caused by the increased mass, but also by the increased friction between the side walls (substantially the bottom) of the shaft 4 and the conveyor segments 5. With increased control of the cutter heads it becomes possible to dig sloping shafts 4 if the geological situation dictates such. In case downwardly sloping shafts 4 the retraction force is enlarged by the gravity forces. It is difficult to increase the power installed in the launch vehicle 1 as this would lead to an undue increase of mass of the launch vehicle 1 and hence the handling capabilities thereof. Also the conveyor segments 5 need to be reinforced to handle such heavy loads.
To avoid these problems the invention provides in a retracting apparatus 6 for retracting the cutter head and the conveyor segments 5 from the shaft 4. The retracting apparatus 6 is adapted to be substantially located besides the path between the launch vehicle 1 and the entrance of the shaft 4 to allow passing of the conveyor segments 5 and the minerals from the shaft 4. However the retracting apparatus comprises a main body 7 outside the path and a connection position where the retracting apparatus 7 is connected to the connection element. This connection position is located within said path, but above the conveyor elements 5 allowing the conveyor elements 5 to perform their function of transport of minerals and other materials.
In the present embodiment the connection element 8 is formed by a cable, which is attached to the cutter element before it started to dug into the shaft 4. In the present embodiment a winch is incorporated in the main body 7 of the retracting apparatus 6. The connection element 8 is guided by a pulley 9 to allow the cable 8 to be curved from the direction at which is leaves the shaft 4 to the direction perpendicular thereto at which it is wound onto a winch 12. The pulley 9 is located on a shaft connected to a frame 10 attached to the main body 7 of the retraction apparatus 6.
The main body 7 of the retracting apparatus 6 comprises a frame 10 which is mounted on two sets of caterpillar tracks 11. On the frame is further located the winch 12 and an engine 13, for instance a diesel engine 13 and a cabin 14 in which the controls for the retracting apparatus 6 are located. The top of the frame 10 is connected to a beam 15 extending in the longitudinal direction of the retracting apparatus 6. The beam 15 extends to the pulley 9, and thus to the connection position. The beam 15 is heavily constructed to protect the retracting apparatus from debris falling from the vertical wall 2 of a geological structure 3,
To withstand the pulling forces generated by the pulling process, the retracting apparatus 6 comprises two vertical supporting elements 16 which are adapted to transmit a horizontal force to the wall 2. The supporting elements 16 are connected to the frame 10 by means of hydraulic cylinders 17. Other linear expansion elements can be used instead. The location of the elements 16 is chosen so that the they are at both sides of the connection position, so that the forces acting on the connection position cannot lead to a torque making the retracting apparatus 6 tilt or rotate.
To give extra support a pair of vertical supporting elements 18 is located at both sides of the connection position, or rather the pulley 9. These supporting elements 18 are adapted to transmit vertical forces to the ground on which the retracting apparatus 6 rests. The supporting elements 18 can be moved in the vertical direction to allow uneven surfaces of the ground. The supporting elements 18 are connected to the frame 10 by means of hydraulic cylinders 19. Other linear expansion elements can be used instead.
It will be clear that by driving the winch 12 by the engine 13 the winch 12 can be used to retract the cutter head and the conveyor elements 5 from the shaft 4.
In the above embodiment a connection element 8 in the form of a cable 8 is used, together with a winch 12. The use of a cable 8 can be combined with a grip device comprising a first gripper which is adapted to grip the cable 8 and transport it over a certain distance after which it is gripped by a second gripper, transported of a certain distance and so on.
It is also possible to make use of a not flexible connection element 8; this requires the use of such a gripping apparatus. However this would also require that the gripping apparatus is located in the elongation of the shaft, as such a connection element cannot be bended.
Finally
It will be clear that many variations can be applied to the embodiment described above without departing from the scope of the invention.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/NL2004/000794 | 11/11/2004 | WO | 00 | 2/4/2008 |
