Examining Use of Absorption Chillers to Produce Mine Air Cooling from Power Generation Plant Waste Heat in Remote Sites

Abstract

For many Australian underground mining operations, the remote nature of the mine has historically led to a reliance on diesel-powered generation stations for site electrical requirements. In addition, the increasing demand for critical minerals is causing mines to expand and increase production at deeper extents. This, combined with hot ambient surface conditions, often requires the implementation of a mine air cooling system to achieve acceptable underground working conditions. Conventional vapour-compression refrigeration systems for mine air cooling can represent a large electrical power user, straining site resources. With major mining companies targeting "net-zero" operations by 2050, conventional vapour-compression systems may not be favourable due to the contribution of greenhouse gas emissions from additional diesel consumption to power the refrigeration machines. Large quantities of waste heat are often available from diesel generators, presenting an opportunity to implement a form of waste heat recovery to improve the site energy balance, resulting in reduced power consumption. One such potential technology is absorption chillers, which use a thermo-chemical process driven by an external heat source to drive the refrigeration cycle. This paper compares the use of absorption chillers with traditional vapour compression machines for a hypothetical Australian mine air cooling application, highlighting the potential reduction in electrical demand, operating cost, diesel consumption, and site greenhouse gas emissions (CO2-equivalent). Consideration for both diesel and battery electric mobile equipment fleets are examined as part of the case study comparison.