- Industri: Mining
- Number of terms: 33118
- Number of blossaries: 0
- Company Profile:
The U.S. Bureau of Mines (USBM) was the primary United States Government agency conducting scientific research and disseminating information on the extraction, processing, use, and conservation of mineral resources.
Founded on May 16, 1910, through the Organic Act (Public Law 179), USBM's missions ...
A method of measuring mine roadway area in which a tape is stretched diagonally across the roadway. Offsets to the roof, floor, and sides are taken at right angles to the tape and on both sides of it. Alternatively, the floor of the cross section is divided into equal increments and vertical offsets to the roof are made at each division. Horizontal offsets to the sidewalls are made from the nearest adjacent vertical offsets. The measurements so obtained are plotted to scale, and the area of the resulting diagram is determined from the plot.
Industry:Mining
A method of measuring mine roadway area in which a tape is stretched diagonally across the roadway. Offsets to the roof, floor, and sides are taken at right angles to the tape and on both sides of it. Alternatively, the floor of the cross section is divided into equal increments and vertical offsets to the roof are made at each division. Horizontal offsets to the sidewalls are made from the nearest adjacent vertical offsets. The measurements so obtained are plotted to scale, and the area of the resulting diagram is determined from the plot.
Industry:Mining
A method of measuring underground rock pressure by determining the velocity of sound through the rock. Sonic velocity is a function of the elastic modulus of the rock traversed by the wave, and this, in turn, is a function of the pressure. A hammer blow on the rock face is used to initiate the sound waves, which are picked up by a microphone placed at the site of the blow and by a second microphone at the other end of the path through the rock under test. The difference between the times of the signals received from the two microphones will equal the time taken by the sonic pulse to pass through the rock. The signals are converted into visible waveforms on the screen of an oscillograph, and these are photographed or otherwise recorded to form a permanent record.
Industry:Mining
A method of mine timbering in which heavy timbers are framed together in rectangular sets, 6 to 7 ft (1.83 to 2.13 m) high, and 4 to 6 ft (1.22 to 1.83 m) square, so as to fill in as the orebody is removed by overhand stoping.
Industry:Mining
A method of mine timbering in which the timbers appear like roof rafters.
Industry:Mining
A method of mining a vein that has been worked out above and in which the shaft is further sunk, with a crosscut being made to the vein at a depth below the previous workings.
Industry:Mining
A method of mining using a system of haulageways beneath the block of ore, which has had its top surface exposed by the removal of the overburden. Over the haulageways are 1372 chutes that extend up to the surface, and are spaced at intervals of 50 ft (15.2 m) or at any other convenient distance. The excavation of the ore begins at the top of the chute, and broken ore is removed by loading it out from the chutes into cars on the haulage level. The ore block is worked from the top down. The method is similar in principle to underhand stoping.
Industry:Mining
A method of mining by which the ore or coal is mined as the excavation advances from the shaft or main opening. Compare: mining retreating
Industry:Mining
A method of mining in which large quantities of low-grade ore are mined without attempt to segregate the high-grade portions. Compare: selective mining
Industry:Mining
