2019 Ghadiri Micro CT investigation of heap bioleaching variables

Heap bioleaching is a hydrometallurgical technology used to facilitate the extraction of valuable metals such as copper, gold, nickel, and uranium from low-grade, typically sulphidic, ores. This process is highly complex and is influenced by interactions of various sub-processes, including the flow of leaching solution around ore particles, mass and heat transfer within and around the particles, chemical reactions, microbially-mediated reactions, and microbial growth. Effective contact of the leaching solution with mineral grains is essential for the oxidation of sulphide minerals. However, a significant proportion of mineral grains is located below the surface of the ore particles, resulting in contact with the liquid occurring through cracks and pores that connect to the surface. The lengthy extraction times and low metal recoveries often observed in heap systems can be attributed to the slow leaching rates of these non-surface mineral grains, as well as the constraints on the effective exposure of these grains. This study investigates these variables using micro-scale X-ray tomography to better understand the access to and interaction of leaching solutions with the sub-surface mineral grains.