Patent Publication Number: US-2009230755-A1

Title: Method and Device for Mining Subsurface Deposits

Description:
The invention relates to a method for mining underground deposits using a mining machine, wherein an upper and a lower drift are driven, which extend on both sides of the deposit to be mined, and a preliminary bore is sunk between the two drifts, as well as a device for carrying out said method. 
     For mining underground deposits, machine types have been developed, which in most cases are displaceable along haulage means parallelly with the seam or deposit. Depending on the mightiness of the seam, different configurations have become known, which, as a rule, are fixed in the drift by the aid of chains or wire rope hoists. From DE-OS 38 09 768, a method for mining underground deposits has, for instance, become known, in which a preliminary bore is sunk between the two initially driven tracks and a milling procedure using contradirectional milling rolls is performed by the aid of a chain or wire rope hoist from the lower driven track to the upper driven track. Due to the steepness of the drift, the exposed or excavated material can each fall down onto a conveying means provided in a driven track. 
     Another method for mining underground deposits is described in AT 410 001 B. Prior to the beginning of the mining process, two galleries are again initially driven on different levels, with the seam extending in the region between those two galleries. After this, a first connection gallery is driven along the seam corresponding to the seam thickness, to which end conventionally designed driving machines or even explosive drilling methods may be employed. In the upper of the two driven galleries, a ramp is formed to support a cable winch so as to enable a mining machine mining the material starting from the first connection gallery to emerge from the seam and be again maneuvered back into the extraction region in an accordingly offset manner. The mining machine employed is, for instance, designed as a so-called “narrow reef miner”, which renders feasible the efficient and economic mining of particularly low seams using the undercutting principle and which also enables the extraction of hard material in the course of the seam track. The undercutting tools used in such mining machines, in particular with hard material, allow for an increased cutting performance due to a substantially higher portion of broken material, wherein such tools working according to the undercutting principle, due to the lumpy parts excavated, enable tunnel driving and mining not only more rapidly and more efficiently, but also with a substantially reduced dust development. With the mining machine known from AT 411 481 B, layer by layer is radially removed from the interior outwards in an undercutting manner by tools fastened to a rotationally driven drill head. 
     In accordance with the invention, the previously described mining methods are to be improved to the effect that, departing from a preliminary bore between an upper and a lower drift, also the mining of very steeply extending deposits will be feasible in a simple manner, whereby, in particular, also the extraction of material in nearly perpendicularly extending seams is to be feasible while, at the same time, ensuring the safe positioning of the mining machine. 
     To solve this object, the method according to the invention is characterized in that a supporting device is fixed at the mouth of the preliminary bore in the upper drift, that a mining machine supported on the supporting device is positioned at the mouth of the preliminary bore so as to be oriented in the longitudinal direction of the preliminary bore, and that the mining machine is advanced from the upper drift to the lower drift corresponding to the course of the preliminary bore. By arranging a supporting device in the upper drift at the mouth of the preliminary bore, the prerequisite is provided for the positioning of the mining machine in the upper drift prior to the start of the break-in procedure and prior to the immersion into the seam, corresponding to the inclination of the course of the seam, so as to enable the mining machine to be arranged and supported at any angle of inclination while, in particular, enabling inclinations of up to 90°, such that even the mining of very steeply located seams will be feasible directly from the upper drift. In this case, the advance of the mining machine is effected from the supporting device in the direction of the preliminary bore from the upper drift to the lower drift. The method according to the invention, thus, merely requires to initially sink a preliminary bore between the upper and the lower drift, with the extraction by the mining machine being already feasible immediately thereupon. 
     When the mining machine has reached the lower drift, it is provided according to a preferred mode of operation that the mining machine is pulled back to the upper drift by the aid of a wire rope hoist. The mining machine is, thus, able to completely emerge from the seam and be again supported on the supporting device. After this, the supporting device can be moved in the upper drift to the next mining position desired so as to enable the mining machine to be maneuvered back into the mining region in an accordingly offset manner. 
     For the haulage of the extracted material, no separate haulage device is necessary in the mining region according to a preferred mode of operation, but it is provided that the extracted material is removed towards the preliminary bore, or in the direction of the already excavated region, by the aid of a clearing tool provided on the mining machine so as to cause the extracted material to fall down through the preliminary bore, or the already excavated region, and reach a haulage device arranged in the lower drift. The material broken loose will, thus, fall into the lower drift by its own weight as soon as it is moved into the preliminary bore by appropriate clearing tools. The removal of the extracted material may advantageously take place during the mining procedure such that material is excavated and the extracted material is removed and hauled in a single operation. Hence results an extremely efficient and time-saving mode of operation. 
     According to a preferred mode of operation, it is proceeded in a manner that material is excavated using disc or roller tools operating on the undercutting principle, thus ensuring a particularly efficient and economic mode of operation as already pointed out in the beginning. 
     In order to ensure the safe support of the mining machine in the upper drift even with very steep and, in particular, nearly perpendicular seams, it is preferably proceeded in a manner that the mining machine is braced within the supporting device designed as a frame-shaped structure by means of extractable props. Such a frame-shaped support structure is, thus, fixed at the mouth of the preliminary bore in the upper drift and, for instance, delimits an interior space whose dimensions in the vertical direction of the mining machine approximately correspond to the thickness of the seam to be worked on. Within the space defined by the frame-shaped support structure, the mining machine can be braced by the aid of the extractable props so as to enable an accordingly precise and safe positioning of the mining machine even at a very steep course of the seam. The frame-shaped support structure in this case must be positioned in the upper drift in such a manner as to enable the mining machine braced within the frame-shaped support structure to be arranged corresponding to the inclination of the course of the seam. 
     The device for carrying out the method according to the invention is characterized by a mining machine as well as a supporting device for supporting the mining machine in the upper drift in the region of the mouth in a position oriented in the longitudinal direction of the preliminary bore. As already mentioned, the supporting device may be designed as a frame-shaped structure within which the mining machine is braceable by the aid of extractable props. To return the mining machine after having reached the lower drift, the mining machine is preferably fastened to the supporting device by the aid of a carrying device, said carrying device advantageously being comprised of a chain hoist or a wire rope hoist. The supporting device in this case is, for instance, provided with a cable winch, by which the mining machine can be pulled back. 
     As already mentioned, a mining machine operating on the undercutting principle is preferably arranged, to which end the configuration is advantageously further developed such that the mining machine carries disc or roller tools rotationally mounted on a pivotable cantilever arm and operating on the undercutting principle. In this respect, a configuration according to AT 411 481 B may, for instance, be chosen, and it is, therefore, preferably provided that the disc or roller tools are fixed to a head drivable for rotation, whose axis of rotation extends substantially in the direction of the axis of the cantilever arm, said axis of rotation of the head carrying the tools being mounted on the machine frame so as to be pivotable about an axis crossing the axis of the cantilever arm and extending upstream of the pivot axis of the cantilever arm arranged transversely to the driving direction, viewed in the driving direction. Further improvement results from a preferred further development, according to which the pivot bearing of the cantilever arm is arranged on a carriage displaceable in the longitudinal direction of the machine frame. Such a configuration allows the mining machine to remain braced within the frame-shaped support structure at the beginning of the break-in procedure and at the beginning of the immersion into the seam, since it will do to advance the carriage along with the disc or roller tools in the longitudinal direction of the machine relative to the machine frame while thereby driving the disc or roller tools into the seam. The support of the mining machine within the support frame can, thus, be maintained at the beginning of the break-in procedure so as to enable the occurring forces to be taken up by the support structure via the extractable props. It is only when the maximum advance of the carriage has been reached that the machine will have to be reset. In order to achieve as stable a positioning of the mining machine as possible within the machine frame and the seam, respectively, the configuration is preferably further developed in a manner that the machine frame is braceable between the floor and the roof via a plurality of props, wherein props are arranged on both sides of the longitudinal central plane of the machine frame, and that at least one further prop is arranged on the carriage in the region of the pivot axis of the pivoting mechanism so as to be adjustable relative to the roof and the floor. 
     In order to ensure the haulage of the extracted material simultaneously with the excavation of the material, the configuration is advantageously devised such that the cantilever arm carries clearing tools, preferably clearing shields, for removing the excavated material in the direction of the preliminary bore. Thereby, the removal of the extracted material is simultaneously effected at a pivotal movement of the cantilever arm carrying the cutting tools, wherein the cantilever arm is pivoted in the direction towards the preliminary bore such that the excavated material will fall down via the preliminary bore onto the lower drift, from where it can be transported off by a separate haulage device. 
    
    
     
       In the following, the invention will be explained in more detail by way of an exemplary embodiment schematically illustrated in the drawing. 
       Therein,  FIG. 1  is a schematic illustration of the mining method by which an inclinedly extending seam is mined between two drifts driven on different levels; 
         FIG. 2  is an enlarged illustration of the upper drift; 
         FIG. 3  is a view of the upper drift along arrow III of  FIG. 2  at the beginning of the mining operation; and 
         FIG. 4  is an illustration corresponding to  FIG. 3  with the mining operation being further advanced. 
     
    
    
     From  FIG. 1  it is apparent that, prior to the beginning of the mining operation, two drifts, namely an upper drift  1  and a lower drift  2 , are initially driven on different levels, with the seam extending in the region between these two drifts  1  and  2 . Subsequently, a preliminary bore  3  is formed along the seam, wherein the inclination a of the preliminary bore  3  between the upper and lower drifts may be up to 90°.  FIG. 2 , on an enlarged scale, depicts the upper drift  1 , which is joined by the preliminary bore  3 . In the region of this juncture or mouth, a supporting device  4  is provided, which is designed as a frame-like structure. The frame-like structure  4  is inclined in accordance with the longitudinal direction of the preliminary bore. At the beginning of the mining operation, the mining machine  5  is braced within the supporting frame  4  by the aid of props  6  such that the mining machine  5  will likewise be arranged in accordance with the inclination of the preliminary bore  3 . 
       FIG. 3  is a top view on the mining machine  5 , from which it is apparent that props  6  are arranged on both sides of the longitudinal axis of the machine. On the front end of the machine  5  is arranged a cantilever arm  7  whose rotating head  8  carries disc or roller tools. The cantilever arm  7  is fixed to the machine frame, or a carriage displaceable relative to the machine frame, so as to be pivotable about a pivot axis  9 , the pivot drive being formed by hydraulic cylinder piston units  10 . By pivoting the cantilever arm  7 , a region  11  adjoining the preliminary bore  3  is exposed, wherein, at a pivotal movement, the extracted material is removed towards the preliminary bore  3  by clearing tools fixed to the cantilever arm  7 , falling down to the lower drift  2  through said bore. While the mining machine  5  in the illustration according to  FIG. 3  is still braced in the frame-like support structure  4  by the aid of the props  10 ,  FIG. 4  depicts a further advanced position of the mining machine  5 , in which the machine is braced against the roof and the floor within the seam.