Mining or in situ disintegration of hard material – Automatic control; signaling or indicating – Ore/rock interface determination during cutting
Reexamination Certificate
2001-12-21
2003-12-23
Shackelford, Heather (Department: 3673)
Mining or in situ disintegration of hard material
Automatic control; signaling or indicating
Ore/rock interface determination during cutting
C299S001050
Reexamination Certificate
active
06666521
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to continuous mining machines engaged in the process of extracting mineral, i.e. coal, trona, etc., from an underground seam. More particularly this invention relates to methods and apparatus employed to detect the location of seam boundaries and to guide the machine to achieve the desired cutting horizons (vertical elevations) relative to those seam boundaries.
BACKGROUND OF THE INVENTION
Continuous mining machines typically include a self-powered, tracked vehicle having a rotary arm pivotally mounted at its forward end. A cutter is rotatably mounted at the distal end of the rotary arm to cut into a coal or ore seam for extraction of the coal or ore by an extraction mechanism provided on the machine.
Various patents exist which describe devices utilized in the mining of coal. Most notably the Lipinsky U.S. Pat. No. (4,952,000) which describes the method and apparatus of HIWALL mining. Lipinsky relies on gamma ray detection as a sensor. However, Lipinsky has determined that mining data on the use of the gamma detectors in Lipinky's invention is limited in significant ways. Lipinsky uses gamma detectors ONLY to measure coal thickness that MUST be left at the roof and the floor of the mined highwall holes. Lipinsky further records coal thickness data on one or more holes, creating a profile of that seam, and then applies the resulting vertical control scheme to the machine on the next adjacent hole. He does not use real time data to try and control the machine in any current hole, but relies on the data on the previously recorded hole to assume what will happen ahead of the machine in the current hole. While he is controlling the machine in the current hole, he is recording data to then be applied to the next hole.
Lipinsky has determined that using data on any current hole for controlling the machine in that current hole is inadequate and not useful, due to the fact that no one has derived a good control scheme to predict what is ahead of the miner. The present control scheme has, however, successfully used real-time data to control the machine in the current tunnel, which would be required in normal room and pillar mining operations, as well as entry driving or roadway driving. Entry and roadway driving, along with room and pillar mining are operations that cannot use Lipinsky's data recording scheme, and thus cannot use his control scheme because there is no parallel holes to record data in, to be applies anywhere else. These types of mining require that control be applied while the gamma detectors are being read, and does not require data recording and post processing, as does Lipinsky's scheme.
Additionally, Lipinsky locates his detectors far back on the machine, and limits them to recording coal thickness data. This inhibits the adequacy of any control operation. This scheme also will not work where all coal is removed, and only rock is left at the roof and floor. The small detector scheme of the present invention, where we look for that dust cloud emitting a burst of gamma radiation, works well where all the coal or ore body is being extracted, and leaving only the seam boundary material.
SUMMARY OF THE INVENTION
The present invention addresses the shortcomings in Lipinsky's patent at least in the following ways:
1. The present invention allows control of the miner in real time, and does not require application of previously recorded coal thickness data for control of the miner. Note that data was recorded over a period of hours during mining of the previous hole.
2. The current invention allows full seam extraction leaving only the seam boundary, and does NOT require coal to be left for it to operate, where Lipinsky requires coal to be left for his gamma detectors. These sense the boundary radiation to determine coal thickness, which is used as means of locating the boundary.
3. When the current invention uses a gamma sensor, it can be mounted on the machine anywhere that has a view of the cutter drum and material currently being cut, whereas Lipinsky's invention is limited to being pointed towards roof or floor areas having a previously cut layer of coal.
4. The current invention uses a gamma sensor to determine the boundary by detecting a burst of gamma radiation when the boundary material is contacted by the cutter, and DOES NOT require coal thickness to be left like in the case of Lipinsky. Coal that is required to be left for the Lipinsky approach could be coal that is recoverable with the current approach.
5. The current invention control scheme can use any type of seam interface detector that will provide indication of cutter contact with the rock boundary and is not limited to gamma sensors.
The present invention provides a means to improve the control of cutting the roof and floor during underground extraction of coal or ore from the seam. Such roof/floor control is commonly referred to as “Horizon Control”. With each forward advance of the mining machine in the seam, the control system locates the seam boundary(s) and directs the elevation of the machine's cutter relative to the seam's upper and/or lower rock boundary(s). Hence the extraction can be controlled to follow the seam boundary(s), avoiding the mining of rock and also providing control of the extraction height as may be required by the mining operation. Therefore, the control system which includes a microprocessor is capable of controlling either the upper or lower cutting horizons or both, during the mineral extraction process.
Sensors provide information for the system to calculate and determine upper and lower seam boundary locations (vertical elevations), machine attitude and cut profiles for the roof and floor as the machine moves continuously forward in a succession of sumping cycles during the coal or ore cutting operation. This information will be used by machine operators and/or the machine's electro-mechanical control system to position the cutter in the seam or ore vein. The assemblage of components to be installed on the continuous mining machine will be referred to as the Horizon Control System. This system will make possible the cutting of a smoother, more uniform roof and floor, at the desired horizons (vertical elevations).
For reference, a “sumping” cycle for a continuous miner typically consists of the following steps:
1. Raise drum type cutter to the mine roof at the desired height (cutter is mounted on a boom that has a pivot at the opposite end).
2. The machine moves forward with the cutter entering the coal/ore face the selected roof height. The cutter travels or “sumps” in to the coal/ore a distance of ½ to ⅔ of its diameter.
3. The arm and the cutter are then lowered, cutting coal or ore from the face, until the cutter reaches the desired floor level. This is called the “downcut”.
4. The machine then backs up to grade the floor and clean up (load) loose coal or ore into the shovel's gathering head.
5. Cycle then repeats itself as the machine moves forward through the seam.
The Horizon Control System is installed on the continuous mining machine. It displays “real-time” guidance information to assist continuous miner operators in positioning the cutter head for desired roof and floor cuts or may be setup to automatically control positioning of cutter head through the miner's electro-hydraulic controls. Using information from multiple sensors, the system provides an “intelligent” display of cutter height, measured from either the last cut floor or the next floor cut during a new sump cut. The display unit also indicates when the cutter has reached the required position for either the next roof or floor cut. However, the machine operator cannot always watch the display unit because he is also involved with other tasks occurring simultaneously, such as loading coal/ore transport vehicle. Therefore, when the cutter has reached the required position, a separate bright “target light” is illuminated to notify operator to stop the cutter vertical travel. Alternately, as previou
Pease Robert E.
Ramsden, Jr. John W.
American Mining Electronics, Inc.
Brantley Larry W.
Shackelford Heather
Singh Sunil
Waddey & Patterson
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