Bulks
At first sight, most pits targeting bulk commodities could look similar to the pits targeting metals and polymetal pits. The major difference in the exploitation strategy and mining methods applied to bulks is generally the massive nature of bulks. Bulks generally include manganese ore, iron ore, bauxite, agricultural minerals, and more.
Pits targeting bulk commodities are generally large and reasonably regular in dimension and extend to fit the geometry of the massive type mineralisation. Based on the shape of the mineralised zone and the economic cut-off grades applied, a relatively low degree of mining selectivity could be required, unless the economic qualities vary significantly in the vertical dimension throughout the massive mineralisation. Appropriate equipment section, blasting practices and grade control practices are critical in these cases.
Large, high production rate pits (1 million tonnes of rock moved per day) are prominent. To allow for such high production rates and to manage this operational risks appropriately, large pushbacks with multi-pit accesses would be considered. Generally, inpit backfill opportunities are more prevalent relative to poly metal pits, depending on the horizontal extent of mineralis ation and pushback strategy. External waste stockpiles will be required and optimal pit, pushback, waste dump and hauling design activities are required to minimise the cost profile of the operation, specifically considering the trend of energy costs. In-pit crushing and conveying systems and trolley-assist lines are frequently applied, where it is practically possible, and where the operational cost savings outweigh the capital investment requirements.
Due to the significant quantity of the saleable bulk commodity tonnes produced relative to the ore mined, the offsite logistics can play a significant role in the overall cost profile of the operation.