Simulation of large-scale thermal storage in fragmented rock modelled as a discretised porous medium – application to the Natural Heat Exchange Area at Creighton Mine

Abstract

The Natural Heat Exchange Area (NHEA) is a large-scale fractured rock mass at Creighton Mine, created by previous sublevel cave mining, that is used to seasonally store thermal energy with the purpose of moderating the temperature of ventilating air for the underground mine. The use of the NHEA has avoided the mechanical cooling and heating otherwise required due to the seasonal variations in ambient temperatures. The NHEA has 96 doors through which air enters the mine airways through the mass of broken rock; these doors are manually operated to improve the tempering capacity. The empirical strategy for operating the doors has proven successful so far, but additional cooling is needed as mining progresses deeper. This paper describes two models, a three-dimensional computational fluid dynamics (CFD) model and an analytical network model. The models are calibrated to agree with the history of measured temperature, airflow and pressure at the NHEA. The calibrated models will be used together to support the assessment of both operation and systems design variations.

An overview of the Nordic mine ventilation system

“…This removes some of the requirement to install an expensive mechanical refrigeration plant and therefore can save significant capital and operational expenditures. Several methods have been proposed and used in Canadian mines located in similar climatic regions, namely the Creighton mine (Sudbury, Ontario) Natural Heat Exchange Area-NHEA, also called Seasonal Thermal Energy Storage-SeTES (Fava et al, 2012;Saeidi, Romero, Fava & Allen, 2017;Ghoreishi-Madiseh, Sasmito, Hassani & Amiri, 2015), ice stopes (Trapani, 2019), and open-loop cold lake cooling (Kuyuk et al, 2019;Ramsden, Allen, Millar & Guse, 2014). It is attractive to employ these methods in Swedish mines, though their suitability for Swedish mines must be assessed.…”