HEAT TRANSFER IN WASTE-ROCK PILES CONSTRUCTED IN A CONTINUOUS PERMAFROST REGION

• Main Author: Pham, Hoang Nam
• Other Authors: Sego, Dave (Civil and Environmental Engineering), Wilson, Ward (Civil and Environmental Engineering), Ulrich, Ania (Civil and Environmental Engineering), Rajaratnam, N (Civil and Environmental Engineering), Flynn, Morris (Mechanical Engineering), Côté, Jean (Civil Engineering, Université Laval)
• Format: Thesis
• Language: English
• Published: University of Alberta. Department of Civil and Environmental Engineering. 2013
• Subjects: geo; envir; Canada; Diavik Diamond Mine; permafrost
• Online Access: http://hdl.handle.net/10402/era.29963

Specialization: Geotechnical Engineering Degree: Doctor of Philosophy Abstract: This study is a part of a field experiment constructed at the Diavik Diamond Mine in northern Canada to investigate water flow, geochemical reactions, thermal and gas transport within unsaturated piles of mine waste rock in a continuous permafrost permafrost. Diavik waste rock is categorized by its sulfur content: Type I rock, Type II rock and Type III rock . Three experiment waste-rock piles of 15 m high were constructed to achieve the project objectives. Two uncovered test piles are referred to as Type I test pile (Type I rock) and Type III test pile (Type III rock). The third test pile is covered test pile in which the Type III rock is covered by a layer of 1.5 m till and 3 m Type I rock. Three drill holes of 40 m depth in a 80 m high pile were also instrumented to reexamine the results of the test piles. This thesis focuses on the thermal aspects of the project. Thermal measurements in the uncovered piles implied the importance of wind on heat transport. Temperatures within the piles were found to decrease with time and permafrost aggradation near the base and in bedrock foundation. At the covered pile, temperatures at and below the till cover were frozen. There was no significant impact of wind on temperatures below the cover and heat influx across the cover was small. Bedrock foundation temperature of the covered pile showed a small cooling trend and less fluctuation compared to bedrock foundation of the uncovered piles. Linear stability analysis for the onset of natural air convection in waste-rock piles with physical properties based on Diavik waste rock was also performed. The results indicate that oxidation can create sufficient temperature gradients (or buoyancy forces) to trigger natural air convection. Ground temperatures of three 40 m drill hole in the 80 m high full-scale pile showed that conduction was dominated and the pile was cooling. According to numerical simulations, using air convection cover (ACC) the 80 m ...