Chapter 3 - Geochemical evaluation of sulfidic tailings and cemented paste backfill with respect to environmental impacts

Abstract

In order to meet the increasing raw material demands of developing and growing economies, millions of tons of mines are processed every year. As a result, billions of tons of mine wastes are generated. Sulfur-containing mine wastes (tailings) can oxidize and acidify the environment causing acid mine drainage (AMD). AMD can lead to the dissolution of heavy (toxic) metals and their transportation to large areas with surface/underground waters. In this way, AMD can damage the environment and ecosystem. Therefore, it is very important to determine the AMD potential of sulfur-containing mine wastes/tailings. AMD potential is estimated from the relation of acid production potential (AP) and neutralization potential (NP) which are determined by static and kinetic tests. Mine wastes/tailings with a strong AP are classified as hazardous mine wastes. Such materials are stored in stockpiles, tailings dams, or underground production cavities as backfill considering the specified legal regulations. Static tests are simple, inexpensive, and short-term tests which are also the first step in the characterization of sulfidic wastes. Kinetic tests are performed on the basis of static test results. Kinetic tests are extensive, time-consuming, expensive, and special tests that can simulate ambient conditions. This study overviews the (1) environmental effects of sulfur-containing mine wastes, (2) determination and characterization of AMD using static and kinetic tests, (3) cemented paste backfill (CPB) and AMD, and (4) the studies performed on the heavy metal release and AMD potential of CPB.