Vale's Coleman mine has extracted minerals from 200-1,700 m depth for over 50 years and is currently expanding 1,850 m. At depth, autocompression effects superimposed on summer climatic conditions, generate increasingly adverse thermal working conditions with temperatures exceeding 40°C DB and 28°C WB. These require heat exposure management through work:recovery regimens and stop work conditions. Through mine planning, Vale recognized they would need cooling, and in 2016 engaged BBE to investigate novel cooling and traditional technologies, assessing both underground and surface options to provide focused to the 170 Orebody. It was identified that although the cooling aspect was feasible, providing the required electrical power, clean water supply, and locating the heat rejection without impacting mine activities would be problematic. In 2019, Vale again engaged BBE to design and supply a surface cooling plant, this included investigating alternative mechanical options, opportunistic coolth storage solutions, and the final provision of an operating turn-key system for the summer of 2020. Considering the 18-month timeline, the capital costs, unproven technologies, and production loss risks, most of the options reviewed were discounted and Vale opted for a conventional vapor compression mechanical system. This paper discusses the challenges of surface and underground cooling, novel options, the installation, and operational challenges of a surface air cooling plant in a northern climate. |
