Cost of Dozer Push
- The unit cost of dozer push sits between dragline and truck/shovel.
- If dozer push replaces dragline prime, its generally to speed up coal uncovery by the dragline.
- If geotechnical conditions are favourable and the dozer fleet is sufficient, dozer push should be considered to replace some of the truck/shovel prime.
Understanding the Cost Drivers
- Push Distance: Dozers are more cost effective over shorter push distances.
- Push grade: Downhill push uses gravity assist, uphill push reduces carry capacity.
- Material: material swell is variable throughout the blast profile.
Truck / Shovel
- Haul distance: Increased fuel consumption, increased number of trucks required to maintain excavator productivity.
- Elevation: Increased fuel consumption, wear and tear on truck, reduced travel speed productivity.
Optimising the Pivot Point
- The point where the blast profile intersects the final lowwall.
- Dozers aim to cut on highwall side of pivot point and fill on the lowwall side.
- Dozing below the pivot point means additional handling of dozer material and less spoil room for bulk doze.
- Raising the pivot point increases the spoil room available for bulk dozer push but introduces dozer rehandle.
- Even with the inclusion of the rehandled dozer material, increasing the volume of prime dozer to reduce truck and shovel movement may be the most cost effective solution
Optimising the Material Allocation
Under the right operational conditions, it would be more cost effective to reallocate a higher percentage of prime material to be moved by dozer push rather than truck and shovel excavation.