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Characterizing and Stabilizing a Historical Tailings Facility: The Rheology to Soil Mechanics Continuum

Characterizing and Stabilizing a Historical Tailings Facility: The Rheology to Soil Mechanics Continuum

Author: Amy Adams, Daniel Friedman, Scott Davidson
Conference: Tailings and Mine Waste 
Date: November 5-8, 2017

Historical tailings facilities often contains materials that have a consistency that ranges from fluid to solid, depending on a number of factors such as particle size, depth, drain-age, and depositional history. Historical impoundments may contain saturated semi-fluid mate-rials at depth, long after tailings deposition has ceased and after surface reclamation has been completed.

This paper presents a case study of the investigations and testing relating to the design and pro-gressive implementation of remedial stabilization measures for the historical tailings facility at the New Afton Mine located in British Columbia, Canada. It was necessary to evaluate both the geotechnical conditions (soil characteristics) of the tailings mass, as well as the potential rheo-logical behaviour (fluid flow characteristics) of loose saturated zones that could be susceptible to liquefaction and migration into the cave zone or underground workings. Therefore, this study relies on integration of the principles of advanced soil mechanics in combination with fluid mechanics and rheology, particularly in relation to slurry viscosity and flow behaviour of contractive potentially liquefiable tailings materials.

A rheological model was developed to characterize the yield stress and flowability of the his-torical tailings deposit. In-situ and laboratory testing was completed to understand the variabil-ity of the tailings in the facility. Simple index properties including moisture content and clay-sized particle fraction were used to characterize the tailings rheology. A field-scale trial pro-gram was implemented to demonstrate that the tailings could be quickly and effectively stabi-lized by densification and dewatering using wick drains, consolidation loading, and dewatering wells.


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