Declining ore grades are increasing the importance of reducing the energy required to crush and grind each tonne of material processed by mining operations. This has made crushing and grinding a major area of technology development as miners seek to manage the growing volumes of material required to produce metal.
Weir is promoting flowsheets that combine high-pressure grinding rolls (HPGR), large-format screening, stirred milling and coarse-particle flotation. The company cites potential energy reductions of up to approximately 40% from HPGR technology and around 38% from stirred milling in suitable applications. Metso is addressing the same processing challenge through HPGR, fine-grinding and vertical-roller-mill technologies. Its Loesche-based dry-grinding systems have been presented as capable of reducing energy requirements by as much as approximately 40% for appropriate ore types.
Energy Consumption and Processing Costs
The reported energy reductions vary significantly depending on the deposit and the processing flowsheet. Their relevance reflects the scale of electricity consumption associated with comminution. Grinding is among the largest electricity consumers at hard-rock mines, while low-grade copper operations can require substantial increases in material movement and milling to generate additional production.
More efficient processing circuits can affect both operating expenditure and infrastructure requirements. Reducing electricity consumption can also lower the amount of new generation, transmission infrastructure and backup capacity required by a project. These factors can influence project development schedules and capital intensity, extending the economic impact of comminution efficiency beyond direct power costs.
Equipment Selection Shifts Toward Efficiency
The focus on energy consumption is also affecting mining equipment procurement. Companies are increasingly evaluating mills and crushers according to energy consumed per tonne, wear rates, maintenance requirements and downstream recovery, rather than throughput alone. Equipment suppliers capable of improving several of these performance measures simultaneously can therefore strengthen their position in equipment selection.
The underlying challenge is linked to declining resource quality. Mining companies cannot depend on increasingly high-grade deposits to maintain metal production. As ore quality deteriorates, producing the same or greater quantities of metal can require processing increasingly difficult material, placing greater emphasis on efficient comminution as part of mine and processing circuit design.
