Experimental study on darkening water-rich mud tailings for accelerating desiccation

Accelerating natural desiccation of water-rich mud tailings deposited in a large open area reduces the impacts and risks of tailing consolidation to the environment and engineering structures. A simple method for accelerating natural desiccation of mud tailings is to reduce the tailings' surface albedo, which however has not been confirmed yet. Here we measure the evaporation of water-rich mud tailings with different albedos, and quantify the shrinkage cracks of these tailings via image processing. Three limited-extent mud tailings samples are prepared, in which one is painted black, the other is painted white, and the resting one is unpainted (original orange color). The results show that lowering the albedo of tailings speeds up the evaporation and desiccation of the tailings greatly. The water content of the black tailings drops from 250% to 10% needs about 6 days, which is 2.5 and 4.5 days before those of the orange one and white one, respectively. The surface shrinkage cracks of the tailings reveal that both the black and original tailings share the same crack pattern, suggesting that the albedo acts the secondary role on the crack pattern. Our findings substantiate that darkening the tailings helps desiccate water-rich mud tailings but does not vary the crack pattern for land reclamations of such tailings. (C) 2019 Elsevier Ltd. All rights reserved.