This invention relates to the mining of friable materials and, more particularly, relates to the mining of friable materials with a continuous miner.
For ease of presentation, this invention will be described in terms of coal.
Continuous miners have found widespread use in the mining of coal, because of the increased production they provide. Generally, the miner includes a conveyor that discharges coal to the rear. That coal commonly is discharged into cars and the coal is transported away from the working area in the cars. Transport of coal as a coal/water slurry in flumes offers potential economic advantages but since a flume is stationary, it is not readily adaptable for use with a mobile continuous miner which not only moves from side to side but also moves forward and backward, to some extent, while mining coal.
It is an object of this invention to provide a method and apparatus whereby material may be readily transported from a continuous miner out of an entry through a flume as a solids/water slurry.
It is a further object of this invention to provide a method and apparatus whereby a mobile continuous miner is directly coupled with a fixed flume.
In one aspect of this invention, there is provided a method of mining materials which comprises:
(1) removing material from the working face of a mine with a continuous miner; PA1 (2) discharging the mined material from the continuous miner into a trough supported by the miner and sloping away from said miner, and having its lower end in cooperative and relatively movable engagement with a flume, said trough being supplied near its upper end at a point above which the material is discharged into it with a flow of water sufficient to carry the material down the trough to said flume; and PA1 (3) transporting said material from the working area as a solids/water slurry in said flume. PA1 (1) a continuous miner with conveyor means to discharge the mined material therefrom; PA1 (2) a sloping flume to transport material from the working area as a solids/water slurry; PA1 (3) a trough supported by said continuous miner and sloping away from said miner, said trough having its upper end positioned below said miner discharge conveyor to receive mined material and having its lower end in cooperative and relatively movable engagement with said flume, and PA1 (4) water supply means to said trough to supply water near the upper end of said trough at a point above which material is discharged from the miner conveyor into said trough.
In another aspect of this invention, there is provided a system which comprises:
By practice of this invention it is possible to connect a fixed flume to a mobile continuous miner in a practical and economic manner. The trough is inexpensive to manufacture yet is very reliable in operation. When compared to a system wherein coal was discharged from a continuous miner into cars and the coal from the cars was then dumped into a flume system the practice of this invention permitted a nine man crew to be reduced to a six man crew. It has been demonstrated that about 50% increase in feet of entry mined per man shift was achieved.
For a flume system to be feasible it is generally necessary to create a gradient of at least 7.degree..+-.3.degree.. Accordingly, shafts or entries driven by the continuous miner should have such a gradient. This presents no problem since continuous miners are readily capable of working on such gradients or slopes.
Flumes are known in the art and may be made of steel, concrete, wood or the like. When using steel flumes, the flume sections may be welded but such measures are not necessary. If the uphill section slightly overlaps the downhill section the momentum of the water moving downhill substantially precludes leakage.
The coal/water slurry for transport through a sloping flume will generally have a coal:water ratio of about 1:4 to about 1:0.5 and the coal size is generally not over about 1/2 the width of the flume. Since coal in smaller sizes is easier to transport in a flume, it is desirable to crush the coal as fine as possible at the face. Therefore, the continuous miner used in the practice of this invention desirably includes breaking means. A simple notched bar placed above the teeth of the miner at a point just prior to the transfer of the coal to the conveyor on the miner has effectively been employed. The use of a roll crusher in cooperation with the conveyor on the miner is also contemplated by this invention.
Desirably the coal is broken so that the maximum size of the lumps is generally less than about one-half the width of the flume. Preferably the coal is broken so that the maximum dimension of the larger lumps is less than about 6 inches, and most preferably, less than about 4 inches. It should be understood that some of the coal may be fine and that some pieces may be larger than the sizes discussed above. The flume can handle occasional pieces which have a maximum dimension slightly less than the width of the flume.
The trough employed in this invention is suspended from the continuous miner beneath the discharge end of the conveyor. The trough preferably is suspended by chains, cables or the like which permit some movement of the trough relative to the conveyor. Alternatively the trough can be supported on a pivot mounted from the continuous miner. The trough is desirably at least as wide at its upper end as the width of the conveyor although a funnel can be employed, if desired, to restrict the flow of coal as it leaves the conveyor and thereby permit the use of a trough which is narrower at its upper end than the conveyor width.
The lower end of the trough is in cooperative and relatively movable engagement with the flume. This may be accomplished by employed a trough with a lower end that is somewhat narrower than the flume width. The lower end of the trough is merely placed in the flume and allowed to slide up or down the flume as the continuous miner moves. Alternatively the lower end of the trough may be equipped with rollers that contact the interior of the flume or the lower end of the trough may be suspended from rollers or wheels that ride along the edges of the trough.
The momentum of the coal/water slurry carries it down the flume and substantially no water backs up the flume even though there is a clearance between the sides of the trough and the sides of the flume. The amount of clearance needed can be determined readily. A clearance of one inch on each side has been found to entirely satisfactory but smaller or larger clearances can be employed depending on trough and flume size, materials of construction or the like.
Often, flumes are located near one wall of the shaft or entry to permit as much access as possible up and down the entry. In such case, the trough is offset to permit the continuous miner to be positioned at and across the center of the entry. In order to provide the offset, the trough may be curved or may contain one or more angles. Since an entry may be 16 feet or or more wide and a continuous miner may work at the far edge of the entry from the flume, the offset between the miner centerline and the flume may be as much as 10 feet or more.