Will AG Milling Make A Comeback?
*M. S. Powell1, A. N. Mainza2, L. M. Tavares3, M. Yahyaei4, D. K. Weatherley4, A. Vien5, M. Mular5, &G. R. Ballantyne6
1 Liner Design Services, 241 Jesmond Rd, Fig Tree Pocket, 4069, Queensland, Australia
2 Centre for Minerals Research (CMR), Dept of Chemical Engineering, University of Cape Town, Rondebosch,7700, South Africa
3 LTM (Laboratory of Mineral Technology), Dept. of Metallurgical and Materials Engineering, UniversidadeFederal do Rio de Janeiro, COPPE-UFRJ, Brazil
4 University of Queensland, SMI-JKMRC, Brisbane, Australia
5 Freeport-McMoRan Inc. 333 N. Central Ave., Phoenix, Arizona, 85004, United States
6 Ausenco, Level 6/189 Grey St, South Brisbane QLD 4101, Australia
(*Corresponding author:
*This paper was presented at SAG Conference held 24-28 September 2023 in Vancouver, Canada. To view the full paper select download file below.
Abstract: The hidden footprint of embodied energy and CO2 emissions of steel grinding media is an overlooked, but ratherobvious pathway to significant reduction in (optional) Scope 3 emissions in the energy-intensive comminutionprocess. The embodied energy of grinding media is around 40% of the direct energy use and up to 60% of CO2energy emissions for SABC circuits, offering up to 40% reduction in comminution emissions. To shift from highball load SAG milling to AG milling requires a considerable mind shift, in terms of addressing operating risk andswitching from high operating cost to higher capital investment with lower Opex (lower specific energy and linerwear in addition to no steel media). Perhaps the greatest perceived risk is in terms of sensitivity to ore variabilityresulting in significant swings in throughput, another is the throughput limitation for highly competent ores. It isproposed that the major hurdle to uptake of AG milling is the ability to reliably predict the circuit performance,especially the dynamics with varying feed competence. This paper addresses the high value of shifting to AGmilling and a pragmatic pathway to adoption through developing the ability to predict performance withconfidence. This can include retrofitting as expansion options by combining with advanced blasting options,compressed bed and conventional crushing. With industry backing this can come to fruition in just a couple ofyears to help support a lowered emission AG milling revolution.
Keywords: AG mill, scale-up, embodied energy, energy reduction