Reducing the amount of water retained in tailings.
COSIA members are also working to reduce net water use intensity by improving how tailings are processed and managed.
Removing water from tailings either prior to it entering the tailings pond or when it becomes trapped between fine solid particles (mature fines tailings) within the tailings pond itself helps make tailings easier and faster to reclaim. The water that is captured is then available for re-use in the recycle circuit or for return to the environment, reducing net water demand from the Athabasca River and its tributaries. Specific projects include:
- Tailings Centrifuge (Syncrude and Shell with all Tailings EPA members)
Uses centrifugal force to extract process water from fluid fine tailings.
- Tailings Reduction Technology (Suncor and Shell with all Tailings EPA members)
Uses chemical flocculants in mature fine tailings to cause clay particles to stick together and release water. The resulting thickened tailings are deposited in thin layers in shallow slopes specifically constructed for drying and dewatering. Here the water is captured and re-used.
- Non-Segregating Tailings (Canadian Natural with all Tailings EPA members)
Uses thickeners and cyclones to significantly dewater tailings before it is sent to the tailings pond. Also, CO2 is added to non-segregating tailings (NST) which further accelerates the release of water. The dewatering process allows warm process water to be captured and re-used.