Froth flotation method and apparatus, a froth flotation method and apparatus for extracting bitumen from a slurry of water and oil sand, and use of the apparatus

A froth flotation method for extracting bitumen from a slurry of water and oil sand containing bitumen, the method including the steps of

• delivering air into the slurry in a flotation vessel to infuse air bubbles into the slurry;
• agitating the slurry in the flotation vessel for dispersing the air bubbles into the slurry said gas bubbles capturing the hydrophobic bitumen from the slurry and forming a froth phase above the slurry phase, said froth to be removed from the vessel by overflow;
• and
• mechanically generating continuously moving negative pressure zones in the froth phase in the flotation vessel before the overflow, said zones extending from the froth phase to the slurry phase and said zones capturing unwanted slurry and water pockets en-trained from the slurry phase to the froth phase and said zones forming paths for guiding said unwanted slurry and water pockets via said paths from the froth phase downwardly back to the slurry phase.

An apparatus for extracting a valuable substance from a slurry (1) comprising a mixture of solid phase, liquid phase and said substance, the apparatus comprising:

• a flotation vessel (2) having an inlet (3) feeding slurry (1) into the flotation vessel;
• a gas dispersion mechanism (4) for delivering into the slurry to infuse gas bubbles into the slurry said gas bubbles being for capturing said substance from the slurry and forming a froth phase (T) above the slurry phase (S);
• means (5) for removing froth from the flotation vessel by overflow;
• and
• means (6) for mechanically generating continuously moving negative pressure zones (7) in the froth phase (F) in the flotation vessel (2) before the overflow so that the negative pressure zones extend from the froth phase (F) to the slurry phase (S) and so that said negative pressure zones capture unwanted slurry and liquid pockets (8) entrained from the slurry phase to the froth phase and form paths for guiding said unwanted slurry and liquid pockets via said paths from the froth phase downwardly back to the slurry phase.