A process and process line is provided for recovering heat in the form of cleaned warm water and residual bitumen from oil sand tailings produced during an oil sands extraction process. The process includes removing at least a portion of the coarse solids from the oil sand tailings to produce a reduced solids tailings fraction; separating at least a portion of the bitumen from the reduced solids tailings fraction to produce a bitumen fraction and a warm water and fines fraction; and removing at least a portion of the fines from the warm water and fines fraction to produce cleaned warm water and a concentrated fines fraction. The cleaned warm water can then be reused in the oil sands extraction process.