Cannington Mine has been developing through paste backfilled stopes since the year 2000. These paste drives have been used as either production drill accesses or long-term bypasses. Prior to this study, the ground support requirements for each paste development cut were: an initial 50 mm layer of fibrecrete, weld mesh bolted with 2.4 m split sets, followed by a second coat of 50 mm fibrecrete. Both layers of fibrecrete and the layer of mesh were to be installed before the next cut could be bored and fired. This support regime proved successful at Cannington, however, the total cycle time for each cut was lengthy due to the installation and curing times associated with each layer of surface support.
In an effort to reduce the cycle
time a study was carried out, with the aid of RocScience’s Phase2 numerical
modelling software. The modelling reviewed all of the parameters controlling the
stability of a newly excavated development cut. The parameters studied included
the early strength of fibrecrete, the ground support load capacity, and the
strength of the paste fill masses which varies depending on the cement content.
As a result of the study, the ground support standard was revised. The revision
has significantly decreased the cycle time as well as fibrecrete consumption,
all the while maintaining the safety of personnel and equipment.
Todd, J K and Campbel, A, 2011. Ground support design and
application for developing in pastefill at BHP Billiton – Cannington mine, in Proceedings 11th AusIMM Underground Operators’
pp 201-206 (The Australasian Institute of
Mining and Metallurgy: Melbourne).