versão On-line ISSN 2411-9717
versão impressa ISSN 0038-223X
J. S. Afr. Inst. Min. Metall. vol.112 no.3 Johannesburg Mar. 2012
The Johannesburg Branch of the SAIMM was recently privileged to host a presentation by Ms Elizabeth Lewis-Gray on the subject of the Coalition for Eco-Efficient Comminution (CEEC), a not-for-profit organization founded by Ms Lewis-Gray in collaboration with several academic luminaries in the field of particle size reduction. CEEC aims to accelerate the transfer of knowledge in the field of eco-efficient comminution by building awareness of the benefits of eco-efficient comminution, such as improved earnings and greater processing throughput to name a few, and to encourage change in the industry.
Ms Lewis-Gray began her talk by sharing the vision and primary activities of the CEEC since its inception in mid-2011. The list of sponsors the Coalition has already attracted is extremely impressive from a South African perspective, including Gold Fields and Xstrata, while internationally AMIRA, Newcrest, and Metso to name but a few, have sponsored the initiative.
Ms Lewis-Gray shocked the room into a stunned silence when she presented a slide which indicated that a massive 4% of total world electrical energy and 30-40% of mine electrical energy globally is consumed by comminution processes. She went on to reveal that only 5% of the energy input into ball milling actually goes into particle size reduction!
Ms Lewis-Gray then went on to discuss some very impressive industry-specific data, primarily from Barrick, who are actively pursuing energy efficiency, and have to date reduced comminution energy on three mine sites by a total of 5.3%, which equates to an annual saving of $5.2 million. The areas on which Barrick have focused include liner profiles, drive methods and mechanisms, and feed size optimization in crushing and grinding circuits. Barrick has set a strategic goal to achieve an overall 8% reduction in mine energy consumption for 2012.
The CEEC is advocating industry investigation and adoption of new technologies to improve comminution energy efficiencies. These include:
The use of crushing to reduce particle size further than has been the historic norm, utilizing the mineralogical matrix of the material to liberate valuable minerals. Equipment such as high pressure grinding rolls and vertical shaft impact crusher technologies have been known for many years, but are only now starting to find mining industry acceptance
Gangue rejection at as coarse a particle size as possible, using sorting or gravity technology.
Optimized feed size distribution by modifying blast patterns.
In closing a fascinating and slightly disturbing presentation, Ms Lewis-Gray urged local industry and individuals to become actively involved in the drive for awareness and debate of eco-efficient comminution and energy efficiency. Precedents have been set by some forward-thinking members of our industry and the onus is on the rest of us to catch up.
The full presentation can be accessed on the SAIMM website, and further details on the CEEC can be found at www.ceeethefuture.org, or via the CEEC LinkedIn page. Members of the Institute are encouraged to join CEEC's LinkedIn group to stay informed on current and future developments.