Laboratory investigation on freeze separation of saline mine waste water

The extraction and upgrading process for bitumen from oil sand deposits in Alberta, Canada currently requires large volumes of process water. This water demand is fulfilled by importing water and recycling/reuse of clarified process water. Reuse of the clarified water results in the steady increase of organic and inorganic (salt) contaminant concentrations in the recycle water. Using a specially designed flume housed in a cold room, trickle freeze separation was evaluated for contaminant separation of saline solutions used as a surrogate for mine waste water. Experiments were conducted at various ambient temperatures, salt concentrations and mass flow rates. Melting proved to be more effective at concentrating salts than freezing. The trickle freeze/thaw process developed during the experiment was very effective at separating and concentrating the salts into a smaller volume. For source waters frozen at an ambient temperature of − 15 °C and with 3000 mg/L (NaCl) or less, 80% removal of salts was possible after melting 9% of the produced ice. For source waters with higher concentrations (20,000 mg/L), 80% removal was possible after melting 27% of the produced ice.