The duty on mine ventilation shafts is usually either intake or exhaust; it is unusual to split the shaft vertically with one compartment an intake and the other an exhaust. Modern mines in Australia also rarely employ "push" or "push-pull" primary ventilation systems; they are almost always surface exhaust ("pull" or extracting) systems. Similarly, underground district (circuit) ventilation systems are almost always designed as exhaust-only. This paper describes an unusual set of circumstances that led to the selection of a conventionally-sunk, concrete-lined, vertically-split primary ventilation shaft with asymmetrical intake and exhaust compartments for a major mine expansion in Indonesia. Site power generation costs are high, so to provide a ventilation-on-demand system to deliver intake air directly to the new working levels as required, an unusual push-pull district ventilation system was also utilized. The split shaft design was also required to facilitate retrofitting of surface refrigeration if the mining depth or level of activities required. A key issue was to ensure satisfactory safety including egress and entrapment design for underground workers. This paper describes the factors impacting on the choice of the ventilation design, the design itself and the management of the risks associated with the design, and the various implementation issues on the site.
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