Since 2010, Barr has provided technology assessment and commercial deployment assistance for the “atmospheric fines drying” (AFD) oil sands tailings management program implemented by Shell Canada (now Canadian Natural Upgrading Limited). The technology is based on in-pipeline flocculant addition and tailings deposition in lifts to capture and dewater fines. A progressive series of laboratory and field testing, analysis, and operational learning over multiple years aided in the design of the facility expansions and development of control schemes that maximized available footprint and fines-drying potential.
In recent years, the development of this technology aimed at optimizing the tailings lift thickness within the operational timeline. The benefits of drying versus self-weight consolidation were evaluated in three field cells. Barr provided test cell design, slurry depositional plans, field logistics, access support, surveying, feed and deposit sampling, geotechnical monitoring, and interpretive reporting for this multiyear study.
Working with other consultants and with Shell personnel, we helped develop a more complete understanding of the water balance and the tailings drying and consolidation processes. The results indicated that deep stacking was a superior approach for short-term deposit performance, but the multiple-lift approach has advantages if there is sufficient time for a lift to consolidate and dry. Current commercial AFD operations leverage many of the learnings garnered from the scaled test programs.