Abstract: In view of the damage to dam body and the pollution to environment caused by high water content of tailings mud, we added dark organic matter admixtures into tailings mud to increase the absorption of solar radiation on tailing mud surface, hence improving the evaporation rate and accelerating the consolidation of tailings mud. Two common dark organic matters, charcoal chips and grass ash, were selected as admixtures in the present study. By comparing the surface evaporation and consolidation process with those of natural tailings mud by means of theoretical analysis and experimental observations, we found that 1) both charcoal and grass ash can boost the evaporation rate of tailings mud, reducing the evaporation time by 32 hours and 24 hours and simultaneously declining the residual water content by 18.8% and 16.5%, respectively; 2) the bottom temperature of tailings mud with charcoal chips and grass ash is about 5-8 °C higher than that of natural tailings mud by absorbing more solar radiation. In conclusion, dark organic matter admixture, as an environmental-friendly material, enhances the consolidation degree of tailings mud, reduces the fluidity of tailings mud significant, and improves the safety performance of tailings pond.

Key words: tailings mud, dark organic matter, evaporative drainage, heat flow balance, soil consolidation