Freeze separation of salt contaminated melt water and sand wash water at snow storage and sand recycling facilities

Freeze separation is used to concentrate dilute salt in snow melt water and sand recycling wash water into concentrated brine that will be supplemented with crystal salt to treat recycled road sand. This reuse decreases the salt released to the environment. Field observations from a case study of a snow storage site in Edmonton, Albert, Canada confirmed freeze separation naturally occurs in snow stockpiles. The first portions of the melt during March had salt concentrations often 10 times higher than the average concentration in the bulk snow. The natural separation of the salts can be further enhanced physically by collecting the first portion (high concentration) of the snow melt and subsequently spraying it into the cold winter air (spray freezing). A spray freezing field investigation was carried out using the sand recycling pond water. Up to 90% of the chloride and sodium was released from cores within the first 19% of the melt water.