Accurate and Simple Prediction of Ice-Melting Capacity in Chloride Deicer Brine Blends

The use of brines is among the most effective ways to reduce application rates and the corresponding environmental impact of chloride deicing salts. Understanding the ice-melting performance of brines is critical for optimizing their application. The ice-melting capacities of 23.3 percent NaCl, 30.0 percent MgCl₂, and 30.0 percent CaCl₂, as well as binary 70/30 and ternary 70/15/15 (by weight) blends of the NaCl brine with MgCl₂ and/or CaCl₂ brines, were measured by a “tracer dilution” approach with coefficients of variation between 0.03 and 0.44 percent. The ice-melting capacities of the individual chloride salts agreed reasonably well with the values predicted from standard reference freezing point depression curves for the individual salts but consistently overestimated them by ∼3 to 5 percent. The ice-melting capacities of the binary brine blends agreed even more closely with theoretical values calculated from the aggregate freezing point depression data for the chloride salts and blends in the literature as determined by an empirical virial equation, giving high confidence that the ice-melting capacity of chloride salt blends can be easily calculated with good accuracy for field application purposes from existing freezing point depression data without the need to test every different brine blend at every temperature. In both binary and ternary blends of NaCl, MgCl₂, and CaCl₂ brines, the ice-melting capacity is essentially the sum of the ice-melting capacities of the individual brine components with no significant synergism apparent.