In a truck shovel operation, all we ever talk about is the excavator. We schedule the excavator, measure it’s productivity, compare various models and make judgements about which ones perform best. But In fact, the excavator doesn’t put any material in the dump or stockpile, its the trucks that do all the work and incur most of the cost of moving the material. So we should really be looking at which is the best truck to use. Assuming that the truck and excavator size are appropriately matched (between 3 and 5 bucket passes to fill a truck), the performance of the excavator only comes into the equation during loading which is perhaps 2 minutes out of a total truck cycle time of 20 minutes. So if the excavator hits some hard dig and takes 3 minutes to load a truck, the excavator productivity will fall by 50% but the truck productivity will only fall by 5% which hardly affects the unit cost of the operation.
Bulk dozer push costs are typically between $1.30 and $2.00 per bcm, and compare favourably with truck shovel costs of up to $4.00 per bcm. Bulk dozer push can be applied in most situations where the coal dip is less than 20 degrees, offsetting other more expensive methods. As the low capital alternative to a dragline, dozers are inexpensive to purchase and move more material per operator hour than all but the largest of excavator fleets.