Abstract
Teck Resources Ltd (Teck) and its research partners have developed and tested the applicability of saturated rock fill (SRF) technology to treat mine-influenced water. In 2018, Teck conducted the first documented full-scale trial of removal of nitrate and selenium from mine water using SRF technology in the saturated zone of a large backfilled open pit in the Elk Valley, British Columbia, Canada. Naturally present microbes in the SRF were leveraged to remove selenium and nitrate from mine-influenced water at flow rates of up to 10,000 m3/d.
Carbon (methanol) and nutrients (phosphorous) were added to source water that was then pumped through a well field in the SRF; this promoted the denitrification of nitrate and bioreduction of selenium to less soluble forms (e.g., selenite, elemental selenium or selenium sulfide).
Over 605 days of testing, 93% (65,000 kg) of injected nitrate and 92% (350 kg) of injected selenium were removed. The trial demonstrated the feasibility of using SRF technology for in situ treatment of water at a mine scale, at one third of the capital cost of comparable tank-based systems.
The trial confirmed that biogeochemical mechanisms could be predicted; it also highlighted the importance of the SRF hydrogeological and biogeochemical characteristics during the design stage and demonstrated that a flexible design was needed to allow responsiveness to changing or unexpected conditions.
This paper provides an overview of the design, operation and results of the full-scale SRF trial.
