"DUAL CONTROL SYSTEM FOR TAILINGS OUTLET OF PRIMARY SEPARATION VESSEL IN THE HOT WATER PROCESS FOR BITUMINOUS SANDS" It has been found that controlling the rate of withdrawal of tailings from a hot water process primary separation vessel with a rake torque sensor is attended by problems when the feed to the vessel is high in fine solids content. It was also found that a nuclear density gauge was much better at controlling the withdrawal with the high fines feed, but did not work as well as rake torque control with low fines feed. Therefore the withdrawal is now controlled with a rake torque sensor when the vessel is receiving low fines feed and a density gauge when it is receiving high fines feed.