A method and system for the use of low quality fuel and solids-rich water, like fine tailings or lime sludge, for extracting bitumen from shallow and deep underground oil sand formations. The method includes the steps of combustion fuel and oxidizing gas, mixing hot combustion gas with solids-rich water under controlled pressure, gasifying the liquid water to steam and solids, removing the solids from the gas phase to generate a solid lean gas, recovering the heat and condensing the steam to generate hot water, mixing the hot water with oilsands ore for extracting bitumen. The solid lean gas is mixed with saturated water to scrub the remaining solids and acid gases and produce saturated steam. The solids-rich saturated water is recycled and gasified by being mixed with the combustion gases, and the saturated steam is condensed to generate heat and condensate for steam generation for use in enhanced oil recovery.