Abstract: A method and apparatus in accordance with the present invention comprising a de-composable compound such as hydrogen peroxide as a primary additive to generate bubbles within a fluid medium such as an aqueous slurry of tar sands. The size range of bubbles, density (number per unit volume) of bubbles, and rate of in situ generations of bubbles are controlled by controlling process variables including but not limited to temperature, concentration of decomposable compound residence time, pressure, viscous shear, ratio of water to solids, pH of the slurry, shape of the separation vessel, and addition of one or more secondary process additives.