Biological leaching of shales - A review

Abstract

An overview of microbial technology for sulfur removal from shales is presented in this paper. Sulfur removal from oil shales through bioprocessing can substantially reduce SO2 emissions from thermal power plants that combust oil shales for energy production. Iron sulfides constitute the most significant inorganic sulfur fraction in shales. There are several Fe- and S-oxidizing microorganisms that have potential for oxidizing iron sulfides to soluble products in acid sulfate-containing solutions. Environmental factors that influence the activities of these organisms are discussed. The organic sulfur compounds in shale matrix are variable and complex. Microbiological transformations of the organic sulfur fraction are poorly understood and it is not clear whether they are amenable to shale bioprocessing. The paper summarizes previously published experimental studies where shales were contacted with bacteria for iron sulfide oxidation. Shales constitute a complex system of study because they contain several phases such as clay minerals, sulfides, organic matter, and carbonates that interact with each other and with microorganisms. © 1998 Institute of Chemistry Estonian Academy of Sciences.