Dry Covers Applied to Coal Tailings

Abstract

Covering coal mining tailings with layers of soil reduces the generation of acid mine drainage. These layers are designed to minimize water seepage and the fow of oxygen into tailing deposits. In Brazil, tailings from mineral coal processing are rich in pyrite, are often stored in piles, and are covered with layers of soil on the surface. This study provides results on the performance of four experimental soil cover models on tailings resulting from coal mining in southern Brazil. Pilotscale physical models were constructed on-site, and the water balance of the covers, suction, volumetric moisture content, temperature in the tailings/cover layers, and quality of released efuent were measured. The covers designed with soil and bottom ash signifcantly reduced the volume of water seepage through the tailings and improved the quality of the generated efuents. Moreover, the results demonstrated that the performance of the cover depends on climate variations, and its behavior varies seasonally.