Mining or in situ disintegration of hard material – Hard material disintegrating machines – Cutter shiftable horizontally
Reexamination Certificate
1998-09-14
2001-08-07
Lillis, Eileen D. (Department: 3673)
Mining or in situ disintegration of hard material
Hard material disintegrating machines
Cutter shiftable horizontally
C299S057000, C299S065000
Reexamination Certificate
active
06270163
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to a method and apparatus for mining minerals, such as coal, from underground seams. More particularly, the present invention relates to a method and apparatus for carrying out high wall and underground mining operations of mineral seams in a highly efficient, safe, and inexpensive manner. More specifically, the present invention relates to a method and apparatus for carrying out high wall and underground mining operations wherein substantially the entirety of a mineral seam can be recovered, selective collapse of the ground into the mined seam can be effected, and the apparatus and method of operation are relatively simple while permitting high production rates.
BACKGROUND ART
Mining equipment has long been a key to economically successful mining operations. Originally, underground mining of thicker seams was the primary focus for coal-mining enterprises. With significant depletion of thick seams and additional focus on the safety and health implications of such mining, more attention has been concentrated in recent years on mining thinner seams of coal in both surface and underground mining operations. To accomplish better economics, surface miners uncovered as much overburden as was economically feasible for a given thickness of coal and then augured underground into the exposed high wall, recovering additional tons without the expense of removing the overburden. Until recently, these were round augers limited to short underground penetration distances. The advent of the high wall miner using a continuous underground mining machine in front of a conveyor system has allowed significant improvement in penetration depths. The major drawbacks in all auger and high wall mining operations have been localized roof falls and leaving enough space between holes to prevent collapse of the complete hill structure. Leaving enough coal to prevent collapse is extremely inefficient in that substantial pockets of coal remain after the mining operation, and there are possibilities of later subsidence into the bore holes in an uncontrolled and unscheduled manner. The aforesaid inefficiency of conventional high wall mining is particularly significant in instances where the surface of the seam follows a curvilinear path, such that only an extremely small fraction of the seam can be retrieved when employing spaced surface holes.
Efforts have been made over the years to improve recovery rates achievable by high wall mining apparatus. In that respect, different cutter head designs have been developed to achieve improved cutting action. There have also been developments in improving power systems and equipment reliability to reduce down time of high wall mining equipment.
Also, efforts have been made to expand the application of high wall miners beyond traditional applications by effecting higher and wider cuts. In this respect, cutter heads with larger diameters have been developed, together with larger motors, increased conveyor speeds, and the requisite interface equipment. Another more sophisticated approach has been the development of equipment that initially cuts a conventional bore and then proceeds to ream the bore to slightly larger dimensions. In this latter respect, a bore is made horizontally, normally with conventional cutting apparatus. In most instances, these high wall miners cut substantially greater quantities of minerals during the entry phase, with the hole size being only slightly augmented by reaming cutters. In this respect, various types of cutters have been developed for the reaming action, which are normally contracted during the conventional cutting and subsequently expanded during the return cutting operation. In other instances, the main cutter may be pivoted or otherwise minimally offset from the hole produced during the entry phase to produce the retreat reaming cut.
These combined cutting and reaming machines achieve only minor productivity advancements in relation to the complexities and disadvantages that are involved. In most instances, the cutters for the reaming operation are normally located rearwardly on the machine from the entry phase cutters. This, of course, presents the possibilities of a roof collapse, which can trap the mining equipment underground. As a result, limitations are frequently applied to the extent of the cut made by the reaming cutters, such as to minimize the possibility of roof collapse. These systems also have the disadvantage that even though round holes are cut, frequently there remain potential subsidence problems years after mining operations are completed. Thus, developments in high wall mining equipment over recent years have, for the most part, involved refinements to existing equipment and methods.
DISCLOSURE OF THE INVENTION
Therefore, an object of the present invention is to provide a mining machine and process that is particularly useful in regard to high wall and underground mining operations in constituting a total subsidence remote mining system. Another object of the present invention is to provide such a mining machine and process wherein a coal seam is entered by cutting a relatively small and narrow rectangular hole, which is, therefore, not prone to accidental collapse during the entry phase of a mining operation. Another object of the present invention is to provide such a mining machine and process wherein wings of substantial length are expanded to carry out cutting during a retreat mining operation, such that a great preponderance of the mining operation is effected during the retreat mining operation. Another object of the present invention is to provide a mining machine that employs a pair of adjacent, vertically-mounted cutter heads that cut a relatively narrow square or rectangular hole during entry into a mineral seam. A further object of the present invention is to provide a mining machine wherein the cutters employed in the entry phase are movably mounted on a pair of wings for positioning at the leading extremity of the wings during the entry cutting operating phase. Still another object of the invention is to provide such a mining machine wherein the cutting heads move along the length of the wings during the spreading of the wings to the retreat cutting position and, thereafter, during the retreat cutting operation. Yet a further object of the invention is to provide such a mining machine wherein each wing contains an auger that transports cut minerals from a seam to an auger conveyor in the mainframe of the machine that, in conjunction with suitable extensible conveying apparatus, transports cut minerals to the surface of the ground.
A still further object of the present invention is to provide a mining machine wherein the cutting width during the retreat cutting phase approaches the length of the two wings. A further object of the present invention is to provide such a mining machine wherein during the retreat cutting phase, each cutting cycle along the leading edge of the wings is followed by movement of the wings in the direction of the retreat cut, which is approximately the diameter of the cutting heads. Yet another object of the present invention is to provide such a mining machine wherein the same two cutters are variously positioned and operated to effect the cutting operations during both the entry and retreat operations of the machine. Yet a further object of the present invention is to provide such a mining machine that allows for essentially complete recovery of a coal seam, irrespective of the terrain conditions, which is not possible with conventional high wall machinery.
Another object of the present invention is to provide a high wall mining machine that allows for total subsidence, which is not possible with existing high wall miners. Another object of the present invention is to provide an underground mining machine that, in not requiring the presence of workers in the subsidence area, allows for recovery of much thinner seams than existing total-recovery systems. Another object of the present invention is to provide such a mining
Hummel Rex A.
Mullet Merle R.
Holmes Limestone Co.
Lillis Eileen D.
Renner Kenner Greive Bobak Taylor & Weber
Singh Sunil
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