Early rejection of gangue – How much energy will it cost to save energy?

Comminution accounts for approximately 30 to 40% of the energy consumed on an average mine site (DOE, 2007) and somewhere from 4 to 9% of Australia’s total energy consumption (Tromans, 2008). Additionally, if one includes the energy embodied in steel grinding consumables, this may increase comminution energy by more than 50% (Musa and Morrison, 2009). Energy savings of up to 50% are theoretically possible by employing novel circuit designs and using smart separation techniques, which reject coarse liberated gangue. A range of different strategies such as selective mining, screening, ore sorting, coarse flotation and dielectrophoresis can be used to reject the coarse liberated gangue at different particle sizes.

These technological advances have the potential to increase the throughput in the comminution circuit, while decreasing the energy consumed per tonne or ounce of metal produced. This paper investigates the energy consumed through sorting, and the optimum position of these technologies in the flow sheet, in terms of energy, cost and risk. The findings form the basis of a methodology that can identify the potential upgrades/changes required to obtain a positive return from these sorting and coarse separation techniques.

Ballantyne, G.R., Hilden, M., Powell, M.S., 2012. Early rejection of gangue – How much energy will it cost to save energy?

In Comminution '12, ed. Wills, B. Mineral Engineering, Capetown, South Africa. Please contact http://www.min-eng.com/ for a full copy of this paper.