Auger Mining
Auger mining is done with a giant machine that operates horizontally as does a brace-and-bit. It bores into the coal seam with bits ranging in size from 2 to 7 feet in diameter, forcing out the coal as a brace-and-bit forces out wood curls when boring into wood.
This means of extracting coal is normally utilized after a seam has been mined by the underground and strip, or contour method.
Augers were first devised and used in the United States in 1945, but on a very limited scale. The first auger built was an electrically driven machine, but all augers since that time have been diesel powered.
This type of mining made its advent in Kentucky in 1949. The Blair and Oldham Coal Company started an auger operation that year, mining the 72-inch seam of Leatherwood 5-A coal near Isom, in Letcher County.
A diesel driven, 54-inch auger was used in this first operation.
The rapidly expanded production of coal by stripping in the mountainous area of Eastern Kentucky during World War Il left many miles of exposed highwalls containing coal seams.
Thus auger mining was quickly adapted in Pike, Perry and other Eastern Kentucky counties.
After several years of experimentation, large, efficient augers of up to 84 inches in diameter have been developed. This 7-foot machine, now operating in Eastern Kentucky, is the largest coal auger in the world.
Smaller augers are used where the overburden consists of massive Sandrock and where the coal seam is too thin for strip mining. Some of these small sized machines use bits ranging from 24 to 84 inches in diameter, including intermittent sizes, depending upon the thickness of the coal seam being mined.
The bits on these machines can be extended horizontally to allow mining up to a depth of 216 feet.
Two of the advantages of this type of mining are:
(1) it affords a high production tonnage, per man. per shift, and (2) it eliminates the need for workers to go underground and is therefore much safer than other types of mining.
Manufacturers have reportedly designed an auger that will mine to a depth of 1.000 feet. These machines are normally operated by two to four men and are usually dragged to the mining site by bull-dozers. However, a few are equipped with hydraulic “walkers” for complete mobility.
Based upon the experience gained from the use of the 84-inch auger in Eastern Kentucky, new underground mining machines are being developed that will bring about tremendous increases in production.
Some experts predict that the production per man, per shift. will be increased many times, with the introduction of these new machines.
The auger combines the mining and haulage actions; the former being the breaking down of the solid coal, and haulage meaning the simultaneous removal of the broken coal.
Boring with the Big Auger
Around the mine we have often heard the expression “Boring With A Big Auger.”
The expression has turned into a reality. Auger mining is an established and economical system of coal mining today. By it a good many tons of coal will be mined which until the development of the “Big Auger” was unminable.
The accompanying pictures give you the story of how this method of mining works.
In the view above you see the machine itself boring the coal out, dumping it onto an elevating conveyor which in turn loads it into a truck. The trucks haul the coal to a loading point, there it is dumped into mine cars for transportation to the tipple where it is crushed to steam coal sizes.
The augers which you see here are 32 inches in diameter.
The machine is operated by two men and in the pictures are HOWARD ANDERSON, the operator, and LONNIE MULLINS, his helper. The truck driver, CARL WRIGHT, had gone to the loading point with a load of coal while Howard and Lonnie were loading the one under the elevator.
The pictures on the lower page give you a closer view of the machine and the augers. At the top is the auger rotating so that you can see the coal falling from the hole down onto the conveyor. In the center to the right is a close-up of the cutting head which does the actual mining.
At the bottom Howard and Lonnie are in the act of pulling a six-foot section of auger from a hole previously drilled to add it to the augers in the hole they are drilling.The machine is operated by two men and in the pictures are HOWARD ANDERSON, the operator, and LONNIE MULLINS, his helper. The truck driver, CARL WRIGHT, had gone to the loading point with a load of coal while Howard and Lonnie were loading the one under the elevator.
The pictures on the lower page give you a closer view of the machine and the augers. At the top is the auger rotating so that you can see the coal falling from the hole down onto the conveyor. In the center to the right is a close-up of the cutting head which does the actual mining.
At the bottom Howard and Lonnie are in the act of pulling a six-foot section of auger from a hole previously drilled to add it to the augers in the hole they are drilling.
Cardox-Hardsog Surface Auger Miners
The Cardox-Hardsocg Auger Miner will never replace, and certainly makes no claims of replacing conventional methods of mining coal. On the contrary, we depend on conventional stripping to do the Auger Miner’s development work. This development work is done automatically for the Auger Miner by common stripping methods, aided by the old law of Marginal Productivity, and the rule of thumb which states, in fact, that usually you can only afford to remove a foot of overburden for every inch of coal.
When the overburden gets too high, the stripping must stop. The coal seam is exposed, and roadways have been developed to the overburdened area. A lot of money has been spent here, the coal cannot be stripped, but with no further development costs, an Auger Miner, manned by an operator and his helper-two men-can mine this otherwise unprofitable coal at the rate of 150 ton per 7 hour shift, 21½ ton per hour, 71/ ton per man shift, or more.
By definition, an auger miner is an adequate power unit attached to a screw conveyor, which is used both as a conveyor and a shaft to drive and revolve a cutting head as deeply and as quickly as possible into a seam of coal. Cardox has developed a line of Auger Miners which have proved to be adequate in drilling up to 32″ diameter holes consistently over 100 feet in depth.
Because of the heights of some seams and the partings in others, these augers are made so that, by the means of hydraulic floor jacks, they can be used to drill immediately above the floor or as high as 60″ above it. In the case of a wide seam, this allows holes to be drilled first in the top and then in the remaining lower part of the seam. Where a parting is to be avoided, the coal can be drilled first above and then below this parting. There are in operation some coal augers capable of drilling 60* diameter holes up to 280 in depth. Because of the limited number of highwalls with benches wide enough to accommodate machines of this size, Cardox has gone into production on the 32″ diameter and small Auger Miners.
The power unit for the 32″ auger is a 145 HP industrial type motor.
This power is transmitted through a hydraulic pump, which creates the lift in the four floor jacks, the thrust to the cutterhead, and the hydraulic hoist for lifting the cutting head and auger sections into place. When the Miner is in position to drill, this 145 HP is transmitted through a clutch, hydraulic coupling, gear reduction and Kelly bar, to the augers which rotate at about 50 revolutions per minute.
The operator controls the jacks, hoist, thrust, and retraction from one control bank of levers. The revolutions of the cutting head are constant; but they are started and stopped through manipulation of the clutch, which is operated at the side of the front of the machine. There are extensions on the thrust, retraction, and hoist controls, located in front of the machine so that the operator can assist his helper in connecting the auger sections. The machine is constructed in two parts, the live and the dead frame. The dead frame consists of four corner posts, which are cylindrical.
These posts contain the four floor jacks. They are cross and angle braced, so as to be absolutely rigid. Besides the floor jacks, one of the front posts supports the hoist and hoist boom, on its top. The live frame, which contains the drilling machinery, is located within the dead frame and is mounted on rollers, which allow the live frame to run forward and backward about 6½ feet. The power to move the live frame is hydraulic and is transmitted through two pistons and airplane cables.
The augers are 6′ in length and are made in various diameters. The auger diameter, in nearly all cases, is one inch less than the cutterhead diameter. These augers are coupled with 3½” square shanks and matching sockets. Rounded ends on the shanks guide easily into the sockets in the coupling process. There is a loose fitting hole in both coupling ends, so that a spring pin may be used to secure the connection when the auger string is retrieved. This pin has no force applied to it during the drilling process.
To drill, the machine is brought into position, usually perpendicular to the coal face and at a distance from it of approximately 6½’. The cutting head is then attaches to the kelly bare opera point comes the of the machine. The plane in which the coal seam runs, may or may not, be previously known; however, from experience we have found that the coal seam can be followed, with little difficulty, up, level, or down, as long as it stays in a single plane.
The outstanding and most perplexing problem connected with auger mining has been the developing of a simple but very accurate method of lining up the drill so that a hole almost as large in diameter as the height of the coal seam, can be drilled into this seam for 100′ or more without running into top or bottom, or the previously drilled hole. In the beginning of our experimentation, a string of 40 or 50 of augers was a very unruly thing indeed, when drilled into a seam of coal. The cutter-head, of course, must take the blame for such unruliness, and many designs of cutting heads were experimented with before encouraging results were obtained.
Notice the pile of slate rock to the right of the man standing. A amateur auger operator can keep a rock picker on his toes.
Although we do not necessarily recommend drilling holes as deep as 150 for maximum efficiency in production, the accuracy of the entire system is provided in fact we are getting a good percentage of 150′ holes, 32″ in diameter, in a seam which is 40″ to 44″ in height. This leaves approximately 6″ of coal top and bottom, for variance, in 150 depth. The average rib which we are leaving between holes is about 8′ to 10″ wide.
Once the plane of the seam is determined, the Cardox drill may be set at the required angle by means of its four hydraulic floor jacks, which may be worked as a unit or individually. When the machine is set, the jacks are locked into place. The actual drilling starts now. The cutting head is securely drilled into the coal, the kelly bar is detached and retracted. The hydraulic hoist is quickly hooked up into a six feet auger section, which is lifted, swung into place, and attached to the Kelly bar on one end and the cutterhead on the other. This operation takes about one minute. The power is again transmitted to the augers by use of the clutch, and the six foot section of auger is drilled into the coal. When the one hole is completed, the cutterhead and the entire string of augers is detached from the Kelly bar, and left in the hole. The machine is then lowered onto two parallel beams, which have on one side, angles attached as rails. The machine has, on the underside of the frame, flanged wheels that run on these rails, so that the machine may be easily moved to the next hole. The palled beams Rare titled, making incline plane, and drill rolls int0 the next position by force of gravity
After the machine is moved over to the new site, it is lined up, and the extra cutterhead starts the new hole. This time, when the head is detached, a chain is fastened to the stored string of augers on one end, and to an extended puller bar on the live frame of the machine. When the Kelly bar is retrieved, this automatically pulls a six foot section of auger from the adjacent hole. The hydraulic hoist is hooked into the auger, which is then detached, swung over into place, and attached to the cutting head and the Kelly bar, as before. This operation continues until the second hole is completed, and the drill is again moved for a new hole. In order to facilitate moves of any distance, the Auger Miner has detachable pneumatic tired wheels.
The Salem 1600 is an excellent unit for smaller contractors. The Salem 1600 can be readily transported from job to job. Travels hole-to-hole on skids mounted under the jacks. This compact machine has great mobility as well as extremely stable footing in even the wettest pits. The Salem 1600 lends itself to all types of augering applications.
Thanks to Kenny Fleming for photos
The Giant Augers
ON THE JOB FOR KENTUCKY OAK, the “world’s biggest” coal auger, with a diameter of 7 ft, has reached production rates of as high as 25½ tpm. Twin chutes at the left permit quick switching from one truck to another in loading. A third chute may be added to permit special loading of 6-in lump. The 7-ft cutting head mounts 100 bits.
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KRCC
Pike County, Elk Foot Branch 1973
Donnie Hall’s Auger/ with his nephew Scotty Hall on 450 JD dozer.
The Salem MC Mul-T
This machine sits low, recovers thin seam coal that other machines can’t and can convert over to drill thicker seams too. The Salem MC Mul-T can handle one, two or three cutting heads, drilling holes from 16″ to 51″ in diameter. The Salem MC Mul-T is operated efficiently by a two man crew making this the highest production, lowest operating cost way to get coal coal out of the ground.
