Mining or in situ disintegration of hard material – Processes – Breaking down by direct contact with fluid
Reexamination Certificate
1999-03-30
2001-09-25
Bagnell, David (Department: 3673)
Mining or in situ disintegration of hard material
Processes
Breaking down by direct contact with fluid
C299S056000
Reexamination Certificate
active
06293628
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally pertains to drilling and mining processes and, more particularly, but not by way of limitation, to a mining system particularly adapted for the recovery of coal from relatively thin, generally horizontal coal seams.
HISTORY OF THE RELATED ART
The recovery of coal from coal seams has been the subject of technical development for centuries. Among the more conventional mining techniques, hydraulic mining systems have found certain industry acceptance. Hydraulic mining typically utilizes high pressure water jets to disintegrate material existing in strata or seams generally disposed overhead of the water jets. The dislodged material is permitted to fall to the floor of the mining area and is transported to the mining surface via gravity and/or water in a flume or slurry pipeline. Along these lines, certain developments in Russia included a series of hydro monitors capable of extracting a strip of coal 3 feet wide and 30 to 40 feet in depth within a matter of minutes. The units were designed to be conveyed on a track to the advancing coal face for extracting the coal. The coal would flow downwardly and be transported to the surface via a flume. Similar techniques to this have found commercial acceptance in China, Canada, and Poland, but with only limited attempts in the United States.
Although hydraulic mining techniques have proven effective in the cutting of a relatively large seam of coal, conventional hydraulic cutting systems do not cut as effectively in narrow seams or when rock strata are present within the coal seams.
Another conventional technique for extracting minerals from subterranean deposits is a scroll auger. Scroll augers have been used to mine relatively thin, generally horizontal seams of coal. Conventional auger mining machines typically include a cylindrical auger having helical vanes used to transport cut coal away from a cutting head located on the front or in by end of the auger. The cutting head typically comprises a mechanical bit centered on the front of the auger. The auger and cutting head are rotated, and advanced into a coal seam, using a conventional auger drill unit that is coupled to the rear or outby end of the auger. As the cutting head is advanced into the borehole, additional auger segments may be added to achieve greater depth.
However, scroll augers are difficult to steer, and therefore such augers tend to migrate into adjacent boreholes or out of the coal seam altogether. In addition, as the cutting head advances away from the drilling unit, more and more power is required to put weight on the cutting head and to turn the auger sections. For both of these reasons, the length of the borehole, and thus the length of a particular section of the coal seam actually mined, are typically limited to distances of less than three hundred feet. Therefore, numerous, expensive access tunnels may be required to mine a given seam of coal.
A need exists in the mining industry for a reliable mining system that addresses the limitations of the above-described conventional mining systems. Specifically, a need exists for auger mining techniques to allow deeper penetration, higher rates of penetration, and improved productivity. This need is even greater with regard to economically mining relatively thin, generally horizontal coal seams.
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Peters William J.
Schwoebel Jeffrey J.
Sult Donald B.
Amvest Systems Inc.
Bagnell David
Jenkens & Gilchrist P.C.
Singh Sunil
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