In an open cut mine, bulk dozer push can be one of the most cost-effective methods of moving overburden. Under the right application, the unit cost of dozer push sits somewhere between a dragline and truck/shovel excavation. So, if geotechnical conditions are favourable and the dozer fleet is sufficient, dozer push should be considered to replace some of the truck/shovel prime. Dozer push can also be used to replace dragline prime. This is because it can speed up the linear progression of the dragline – which in many cases will lower the dragline unit cost rate and increase coal uncovery.
With the spike in the coal price many open cut coal mines are looking at an increase in the amount of dozer push as a strategy to increase the overall stripping cost and uncover more coal. The flexibility of bulk dozer push allows it to respond effectively to changes in the schedule.
The 5 P’s are important in Bulk Dozer Push. Prior Planning Prevents Poor Performance.
Simply pegging out the pivot point and letting the dozers loose can result in lost opportunities. One of the most effective ways to design dozer push is using sections, then joining the sections to make 3D surfaces. Firstly, evaluate the pivot point location – should it be the standard projection from coal edge or is there an advantage in raising the pivot line?
Bulk dozer push is applicable to a range of situations and can be applied in flat dip strip mines and steep dip mines using apparent dip stripping. Bulk dozer push uses the void created by coal mining to move material to spoil cheaply. Generally, dozer push is applicable to spoil up to 60m above the basal seam, with prestrip applied to the upper waste as the depth to coal increases.
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.