Improving Energy Efficiency and Reducing Carbon Footprint at the FMR Greenfields Mill Operation
S Latchireddi (1), R Latchireddi (1), P Fallon (2), B Tully (2), and B Hooper (1)
- EEMS Australia, Unit 19/12-16 East Victoria Park WA 6101, Australia, This email address is being protected from spambots. You need JavaScript enabled to view it.
- FMR Greenfields Mill Operaion, Coolgardie, WA 6429, Australia, This email address is being protected from spambots. You need JavaScript enabled to view it.
ABSTRACT:
Comminution is energy intensive and a major contributor to the carbon footprint of the resources sector. Morrell (2022) estimated that the global installed motor capacity of ball mills is approximately 67.6 billion kWh - 58% of the total estimated annual global comminution electricity consumption. More than a century ago, in 1914 (Van Winkle, 1918), it was well demonstrated that Marcy open-ended grate discharge ball mills are more energy efficient compared to Hardinge overflow ball mills. However, overflow mills have become dominant due to the inability of trunnion-based grate-pulp lifter discharge ball
mills to reproduce the expected performance of open-ended grate discharge mills because of internal material transport issues.
The invention of the dual chamber pulp lifter, energy efficient pulp lifter (EEPL), which eliminates the internal material transport issues, namely flow-back and carry-over, and hence ensures efficient grinding conditions, thus allows the trunnion-based grate-pulp lifter ball mills to operate like open-ended grate discharge ball mills. This has generated research interest to understand and demonstrate the century old proven benefits of open-ended grate discharge mills.
Comprehensive laboratory and pilot mill studies undertaken at the University of Utah have once again demonstrated the significant energy savings of open-ended grate discharge mills compared to overflow mills, which have led to successful industrial installations.
This paper summarises the results from three implementations between 2015 and 2022, at copper, magnetite, and gold milling operations. This paper further discusses the energy savings and other benefits observed at the most recent (2022) implementation at FMR Greenfields Mill Operation in Australia. All three operations have demonstrated energy savings of over 25%, in addition to an increase in throughput.
After successful conversion of one out of three overflow mills (one primary and two secondary mills), specifically secondary Mill#2, at the Greenfields Mill Operation in March 2022, the plant is operating with one primary mill and one secondary mill instead of two secondary mills; demonstrating the ability of one grate discharge mill to do the work of two overflow mills, in addition to saving 510 kWh of motor power and decreasing grinding media consumption by 19.7%. Electrical energy savings alone remove 2268 tonnes of CO2 emissions per annum (22% of the operations emission) besides reducing 244 tonnes of CO2 emissions per annum due to reduction in media consumption.
In the next phase of the project, FMR Greenfields Mill Operation will review the upgrade of the primary Mill#3 from an overflow mill to an EEMS discharge system based on the results of the Mill#2 grate conversion. This is expected to further increase power savings by ~300 kWh, decrease the total carbon footprint by 3869 tonnes (35.2% of total), and provide circuit flexibility when toll treating different ore types.