Orano Canada Inc. (Orano) undertook a tailings deposition review for the JEB Pit Tailings Management Facility (TMF) at the McClean Lake uranium mill in northern Saskatchewan to optimize the utilization of available tailings storage capacity. After initial screening, two tailings deposition alternatives were advanced to the detailed review stage. The first option included continuing deposition using tremie injection but with the implementation of satellite deposition barges placed radially from the existing barge. The second option utilized subaqueous rather than tremie deposition. Subaqueous deposition offered several advantages but was a fundamental shift in the tailings deposition methodology and had to be investigated and proven suitable prior to implementation on site.
Computational fluid dynamics (CFD) was used to assess the expected suspended solids and relative impact on placed density during subaqueous deposition using different diffuser concepts. Deposition simulations assessed the accumulation of tailings during a short-term test.
Following concept development and computational optimization, a 25-day field trial was conducted to assess the full-scale behaviour of subaqueous deposition using a horizontal trumpet style diffuser. The results from this test were consistent with the predicted behaviour in both the CFD and deposition modelling. Following the successful field trial, Orano proceeded with full scale, multi-deposition point implementation in 2018. This paper discusses the CFD analyses, field trial performance, and longer-term operation of the subaqueous deposition system.
