Treatment of primary tailings and middlings from the hot water extraction process for recovering bitumen from tar sand

A method for continuously recovering bitumen from a feed stream comprising water, sand, fines, and bitumen in a vessel having a conical lower end and which defines a processing chamber, comprising:

• delivering said feed stream to be processed at the surface of the body of middlings already in the chamber;
• substantially simultaneously contacting the newly added feed with a current of outwardly and generally horizontally moving aerated middlings;
• whereby said newly added feed moves generally radially of the chamber in contact with the aerated middlings current, part of the bitumen contained in said newly added feed forms a froth layer at the surface of the body, bitumen-depleted feed forms a body of middlings in the chamber below the froth layer, and sand particles contained in said newly added feed settle downwardly;
• concentrating the settling sand particles in the conical lower end of the vessel into the form of a dense solids bed, thereby separating the greatest part of the liquid phase from the solids phase;
• recovering the greatest part of the froth from the vessel;
• withdrawing an underflow tailings stream from the base of the vessel;
• and
• withdrawing a middlings stream from the vessel mid-section.