The Callie Underground Mine is located in the Tanami Desert 560 km Northwest of Alice Springs in the Northern Territory and is currently operated by Newmont Australia Limited with all mining activities carried out by Henry Walker Eltin. Callie was discovered in the region in 1991 with the box cut portal commenced south of the pit in 1995 and underground ore production commenced in 1998, after completion of the profitable Callie Open Pit._x000D_
Development is currently occurring at depths of over 700 m with the decline currently below the 640 Reduced Level (RL) level (surface RL of 1400) with production haulage from 600 m below the surface. The combination of auto compression, a moderate geothermal gradient of 2C/100 m and diesel heat transfer causes the wet bulb temperature of intake air at the bottom of the mine to be typically 5C higher than on the surface. Wet Bulb temperatures can be up 5C higher again in active areas under secondary ventilation._x000D_
During the 2002/2003 wet season many activities in the lower levels of the mine were stopped due to miners experiencing adverse heat related symptoms or the temperatures exceeding the Underground Heat Management Procedure stop job criteria of 32C wet bulb._x000D_
To improve the working environment, combat the heat related illness and improve operational efficiency, a temporary 1.8 MW refrigerated cooling plant consisting of three 600 kW modules were installed underground to provide bulk air cooling for the lower levels of the mine during the 2003/2004 wet season._x000D_
Several studies have been conducted in relation to future ventilation demands at Callie and all came to the conclusion, that some mine cooling will be necessary for Callie to meet the high production and development demands._x000D_
This paper will describe the ventilation network at the Callie Underground operation focusing on the installation, operation and effectiveness of the temporary underground refrigeration plant._x000D_
FORMAL CITATION:Smith, D, 2005. Underground bulk cooling at Callie Underground Mine, in Proceedings Ninth Underground Operators' Conference 2005, pp 409-414 (The Australasian Institute of Mining and Metallurgy: Melbourne).