ABSTRACT
Bioleaching is a mineral extraction process, which recovers metals from low-grade ores using bacteria. This is principally applied to copper but also with application to nickel, gold and other metal ores. It is estimated that up to 20% of the world’s copper production is attributable to bioleaching. The main techniques employed are heap and dump leaching. Bioleaching of heaps and low-grade dumps is an important application because of the low capital and operating costs, operational simplicity, and environmental advantages including no slurry tailings disposal. These techniques are used in South and North America, Australia, China, and in one case Finland, but this is not widely used in Russia. Bioleaching is applicable for different climate conditions including cold regions, though special procedures are required to adapt to subarctic climates.
This paper focuses on the geotechnical effects of bioleaching. Bioleaching can be attributed to the production of organic acids and biogases, the formation of Extracellular Polymeric Substance (EPS), growth of biomass, and biofouling by the microorganisms. These processes lead to a weakening of rocks and soils properties including permeability, strength, and deformability and impact slope stability and permeability. This paper presents an overview on fundamentals of bioleaching and its impact on engineering properties of rocks including waste rock dumps.
