Powell, Yahyaei, Mainza, Tavares
Presented at the AusIMM Mill Operators Conference Brisbane, Australia 23 - 25 June 2021
ABSTRACT
Maintaining the work balance between the primary SAG mill and secondary ball mill(s) is an overlooked bottleneck, and thus opportunity, in an increasing number of circuits worldwide. As circuit capacities are expanded by ‘releasing’the SAG mill bottleneck, the work is progressively passed on to the downstream ball mills. This tends to be absorbed as a coarser grind and usually the consequential reduction in recovery, until it is dealt with through addition of extra milling capacity.
However, there is abundant opportunity to rebalance the circuit in advance to recover recovery and open up additional grinding capacity across the circuit.Common causes of loss of milling efficiency are addressed, along with practical techniques to identify mill overload, supported by plant data showing capacity gains in excess of ten percent. Routes to redressing the ball mill overload are provided.
ACKNOWLEDGEMENTS
The tremendous support of our co-workers and the many sites where we have conducted survey and process improvement studiesis sincerely acknowledged
AUTHORS
MS Powell1,2, M Yahyaei3, AN Mainza4 and LM Tavares5
1. FAusIMM,Comminution Reimagined, Brisbane Qld4069.
2. Emeritus Professor, JKMRC, Sustainable Minerals Institute, University of Queensland, St Lucia Qld 4068. Email:
3. Associate Professor SMI-JKMRC, University of Queensland, Indooroopilly Qld 4068. Email:
4. Head of Department, Professor, CMR –Department of Chemical Engineering, University of Cape Town, Rondebosch 7700, South Africa. Email:
5. Professor Department of Metallurgical and Materials Engineering, Universidade Federal do Rio de Janeiro, COPPE-UFRJ, Rio de Janeiro RJ, Brazil. Email:
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