ABSTRACT
Open stoping, with associated pillar recovery, accounts for about 60% of Mount Isa Mines Limited’s annual Lead/Zinc/Silver ore production of 3.4 million tonnes. In some of these stopes cable support has been used in an attempt to maintain hangingwall stability and hence minimise dilution. Individual stopes where cables have been installed are commonly up to 30 m along strike and 150 m high, containing up to 300 000 tonnes of ore.
Hangingwall failures have occurred in stopes in spite of cable support being installed, thus highlighting the need for a detailed investigation of the effectiveness of the support technique.
A decision was made by the Company to increase its research and development, both internally and externally, into cable support. Part of this involved supporting a research project on cable support of open stopes which was sponsored by seven Australian mining companies, co-ordinated by the Australian Mineral Industries Research Association (AMIRA) and undertaken by Mining Research Associates (MRA).
Case study areas were chosen at Mount Isa and two new approaches to cable support design were developed and implemented. Mining has recently been completed in both areas and the observed improvement in hangingwall stability is discussed and illustrated in the paper.
