Recent Improvements in the Milling Circuit at Tropicana Mine

G R Ballantyne, M Di Trento, I Lovatt and B Putland

MetPlant 2017 – Metallurgical Plant Design and Operating Strategies – World’s Best Practice, 11-12 Sep 2017, Perth, Australia


The Tropicana Gold Mine, owned by AngloGold Ashanti Australia Ltd (70% owned and managed) and Independence Group NL (30%) is located 330 kilometres east-northeast of Kalgoorlie, Australia, in the newly developed Albany-Fraser Orogen. Following extensive feasibility studies, a high pressure grinding roll (HPGR)-ball milling circuit was selected based on the reduced power requirements and thus reduced operating expenses. The HPGR-ball mill circuit was estimated to require 75% of the energy of a standard semi-autogenous grinding (SAG) mill circuit. Even with an anticipated greater capital cost, the HPGR-ball mill circuit was found to give significantly better financial returns in all cases investigated in the feasibility study. A comparison between the specific energy requirements of the HPGR, crush and SAG based circuits (SABC) from the feasibility work was conducted and the HPGR circuit was found to be considerably more energy efficient. A survey was conducted and the efficiency of the HPGR was similar to both the overall circuit design and the HPGR laboratory results, reflecting the accuracy that is possible for design and operation of HPGR circuits.

Between 2015 to 2016, the Tropicana circuit has achieved a 20% increase in throughput from 780 to 930 t/h, and this increase has been maintained in 2017. This improvement can largely be attributed to upgrades to material handling processes, increased HPGR speed and smaller HPGR screen apertures. The result of these changes has been to increase the ball mill capacity by increasing the breakage conducted by the HPGR.


G R Ballantyne (1), M Di Trento (2), I Lovatt (3) and B Putland (4)

(1) – GAusIMM, Research Fellow, The University of Queensland, Sustainable Minerals Institute, Julius Kruttschnitt Mineral Research Centre, 40 Isles Road, Indooroopilly Qld 4068. Email: This email address is being protected from spambots. You need JavaScript enabled to view it.

(2) – MAusIMM, AngloGold Ashanti Australia Ltd, Tropicana Gold Mine

(3) – MAusIMM, Orway Mineral Consultants

(4) – FAusIMM, Orway Mineral Consultants

Please contact the authors for further details of this paper.


CEEC acknowledges and thanks the Australasian Institute of Mining and Metallurgy and MetPlant convenors and organising committee for organising the MetPlant 2017 Conference.

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