Mining in focus
In the case of an opencast mine , mine planning will also take geological , product specification , and equipment sizing into consideration .
quality cut-offs , and geological losses . Choosing an approach to dilution and loss will relate primarily to the assumed mining equipment , quality considerations , and the economic margin of the ore . There are three main approaches , namely inclusive , exclusive , and standard . Product specifications and the associated cut-offs that define volumes of saleable product are traded off against typical economic mining cut-off grades .
Based on the drilling samples , the economic interval of the mineralised reef or ore body can be determined . The ‘ best cut ’ must then be determined by the mine planner . The ‘ best cut ’ refers to the optimal high to which an underground face and resulting tunnel can be developed .
This ‘ best cut ’ calculation must consider the grade of the material and the client ’ s requirements as determined by the marketing department , such as element ratios . The mine planning also needs to consider the limitations of the mining equipment . The minimum physical dimensions for the trackless machinery to operate , such as height with canopy and turning angle , needs to be factored in . The face height will also be determined by the safe operating limits , such as the reach height of the drill rig boom and roof bolters . The mining method and the resulting environmental requirements will also determine the mine plan . An example would be board-and-pillar mining operations , where the layout of the mine would resemble a Christmas tree , to optimise ventilation and cycle times from the face to the main drive .
Planning an open pit
In the case of an opencast mine , the mine planning will also take geological , product specification , and equipment sizing into consideration . The geotechnical characterisation of the host rock will determine the bench heights . The amount of overburden that needs to be removed to reach the ore will determine the stripping ratio . The block model will then be developed and various scenarios applied , through approaches such as
Whittle Optimisation , to determine the pit shell . The physical limitation of the drill rigs that drill the blast holes and the effectiveness of the emulsion explosives both have an impact on the fragmentation , which affects the load and haul capacity and the cycle times of the trackless equipment .
Mine planning and scheduling also need to be able to adjust the short-term planning in case a deviation is required . This could be intersecting blind dykes or faults or having working faces declared unsafe due to insufficient ventilation or support . The short-term mine plan then needs to be adjusted to minimise the lost time by doing a trade-off between moving to a new working face , processing stockpiles or lower-grade material , or surface blending of stockpile material . The mine schedule also needs to consider the average advance per blast and the cycle time . The cycle time refers to the time it takes to prepare a face for blasting , making the area safe to access , load , and haul the blast heap material ; installing support ;