BOX CUT AND DEVELOPMENT OF BENCHES BOX-CUT Definition Box cut is the initial/first cut given for the physical development of a mine. This cut generally looks like a box having walls on all sides. The main objectives of box cut are – to reach the ore body, to provide a smooth entry into the pit and to facilitate the development of working benches.
Box%cut Objectives
The objectives of box cut are
To reach the ore body / coal seam To provide a smooth entry to the pit To provide space for development of working / production benches
Tyes Tyes !n" A#ic!bi#ity
Box cuts are of two types – !nternal box cut and "xternal box cut. External box cut
#hen the box cut is placed totally outside the minerali$ed $one, it is called an external box cut. This is applicable only for shallow and gently dipping bedded deposits. The cut is generally located at the middle of the rise%most side. Internal box cut #hen the box cut is located fully or partially on the minerali$ed $one, it is called an internal box cut. This is applicable for all types of deposit. The cut follows a direction that is usually obli&ue to both the strike and dip direction. 'enerally, the direction is so chosen that the haul road ramp formed by this cut and subse&uent cuts will not have unnecessary steep turning at any position.
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DEVELOPMENT $ FO%MAT&ON FO%MAT&ON OF BENCHES
(nce the box cut is established upto the ) st bench floor level, the development of the )st bench is started. (nce the ) st bench is developed over a considerable area, either the existing box cut is widened and extended or a new cut is made to reach the next bench floor level for development of the same, and the process continues for development of the mine benches.
2ormation of Benches by "stablishing *dditional 3ut
2ormation of Benches by "xtending the 2irst 3ut Benc' P!(!)ete(s
* surface mine bench is characteri$ed characteri$ed by the following following bench parameters parameters – Bench height, Bench width, Bench length, Bench face slope and Bench floor slope.
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criteria – (ptimum height for loading efficiency of the excavator, one pass drilling length length should should pref prefera erably bly be more more than than the the bench bench heigh height, t, and and the blen blendin ding g re&uirement dictated by the geological parameters.
: % Bench :eight
# – Bench #idth α %
; – Bench ;ength
Bench 2ace -lope
Bench
