Development of a Mine Area

the division of a mine area by means of excavations into zones appropriate to mining and geological conditions and the technology chosen to work the deposit. In the USSR, the major methods used to divide a mine area into working zones are the level, panel, block, and combined development methods.

In the level method, the mine area is divided into levels according to the dip of the seam or stratum by haulage and ventilation drifts; these drifts begin at the major opening excavation. Depending on the mining and geological conditions and the extraction technology, the height of the level usually varies from 50 to 300 m. When necessary, a level is divided vertically into two, three, or four sublevels.

In the panel method, the mine area is divided into two segments on the level of the pit bottom by excavations of the main haulage horizon. These two segments, the raise and sink areas, are then divided by width into panel segments. Within each panel, a ramp or incline is passed in the central section (bidirectional panels) or at the panel edges (unidirectional panels). The panels are up to 3 km long. A panel is divided by drifts into floors or excavation columns that are from 50 to 200 m wide. The panel method of development is used to work gently sloping and horizontal beds of varying thickness and is very efficient for extensive mine areas.

The block method of developing mine areas is used if mines have high productive capacity or if the mine area is more than 6 km long and methane content exceeds 10 m³ per ton of daily output.

A combined method of development may be used within a single mine area.

In the horizontal development of mine areas, all excavations to develop the stratum are made on the level of the transport or ventilation horizon. Inclined drifts are cut to prepare columns no less than 800 m long so that the columns may be removed either upwards or downwards. When unstable wall rock makes the development drifts in the stratum difficult to support, the major haulage and ventilation drifts are placed in more stable rock. This is also done to create isolated excavation areas in strata with spontaneously combustible coal. Working a series of strata involves independent development of each stratum or the use of group development. In group development of two or more strata, the major haulage and ventilation drifts are placed and supported in an idle stratum or one that is being worked and also in wall rock; the drifts are joined to stratum excavations by intermediate crosscuts or connectors. Group development allows large-diameter passageways and secondary excavations to be shorter, facilitates the operation of underground transport, and reduces mineral loss in the blocks of untouched ore.

The method of development is determined by a comparison of the technological and economic aspects of possible variants. The comparison is based on mathematical economic models and takes into account the major geological, operational, and technological factors.

Development includes the stage of mining in which excavations are made in a bed of a useful mineral or in surrounding rock to permit subsequent cutting and working operations. Development creates lines for ventilation, electrical channels, personnel movement, and the transportation of loads between working faces and opening excavations.