Material transport plays a significant role in the efficiency of horizontal grinding mills – autogenous (AG)/semi-autogenous (SAG)/ball mills. The magnitude of benefits that can be achieved with efficient material transport in AG/SAG mills has been demonstrated in a greenfield milling operation at Mirabela Mineração’s SantaRita Nickel operation located in north eastern Bahia in Brazil. This grinding circuit was commissioned in October 2009, was designed as a typical SABC circuit to grind 4.6 Mt/a (575 t/h) to produce a P80 of 125 µm with ten to 12 per cent ball charge in the SAG mill. However, it has been operating as an ABC circuit without any grinding media in SAG mill. The nameplate design capacity was achieved in few days and was gradually increased to an average of +800 t/h, still operating in ABC mode. The Santa Rita grinding circuit consists of one 30 ft × 15.4 ft 8.5 MW SAG mill fitted with Outotec patented Turbo Pulp Lifters (TPL™) in closed circuit with a HP400 short head pebble crusher and one 20 ft × 28.4 ft 5.5 MW Ball Mill in closed circuit with a Warman cyclone cluster fitted with 10 × 26 in CAVEX cyclones.
This paper examines the comminution design process, operating philosophies, experiences, post commissioning optimisation and future development works. Evaluation of the milling circuit performance relative to the design criteria is also discussed.
De Souza, A B, Latchireddi, S, Moreira, A and
Faria, E, 2012. Application of turbo pulp lifter in greenfield operation –
Mirabela SantaRita nickel operation, in Proceedings 11th AusIMM Mill
Operators’ Conference, pp 53-58 (The Australasian Institute of Mining and Metallurgy: Melbourne).