Evaporative Drying of Dredged Material

Abstract

An approximate, closed‐form solution to the equation governing the evaporative drying of dredged material is presented. This solution includes both the constant‐rate and the falling‐rate drying periods. Different solutions are obtained for two basic geometric cases of “semi‐infinite” and “thin” material layers, and the analysis provides a definition to differentiate these two cases. The solutions are compared with laboratory drying tests of actual dredge spoil from Charleston Harbor, S. C., and show good agreement. Finally, the solutions are compared with drying tests of other researchers for material from Toledo, Mobile, Philadelphia, and Norfolk. Predictions were best for the finer materials, and the closed‐form solution performed (in all cases) better than the use of pan evaporation to predict drying rates. This approach has advantages in that the degree of drying can be computed directly, without having to rely on a numerical solution (beginning at time zero) to obtain intermediate values of drying.