The presence of sand in heavy oil production is known to enhance oil recovery Sand can also be detrimental depending on the properties of the sand-water interface. In this process, the water soluble material interacts with both sand and oil droplets and affects emulsion stability. The formation and stability of heavy oil-in-water emulsions during turbulent flow using batch process stirred-tank mixing of oil, sand, and water were investigated at three pH. Size distributions were measured by laser diffraction. High-speed video photomicrography was used to observe the process during mixing Results showed that the presence of sand enhanced formation of stable. fine emulsion at basic pH 8.5. When the pH of the water was reduced below, 6.5 both sand and droplets surface properties changed, the emulsions became less stable and coalescence was apparent. The sand grains acted as coalescers at low pH and enhanced breakage at high pH. (C) Her Majesty the Queen in Right of Canada, as represented by the Minister of Natural Resources, 2008 AIChE J, 55: 232-242, 2009