Bioleaching and Chemical Leaching of Lateritic Ore in Percolators

Abstract

This work presents results of an initial exploration of nickel and cobalt bioleaching from lateritic ores in small percolators, which serve as simulations of the heap leaching process. Heap leaching offers an attractive alternative to high-pressure acid leaching of laterites, owing to its relatively simple technology, reduced capital and operational expenses, and lower carbon dioxide emissions. Conventional heap leaching of laterites relies on sulfuric acid leaching. Typically, this process consumes 400-500 kg/t of ore, necessitating the construction of a costly on-site sulfuric acid plant. However, the metabolic activity of sulfur-oxidizing bacteria can generate sulfuric acid while reducing ferric to ferrous iron, facilitating mineral dissolution through a combined protonation and reduction effect. Implementing this process eliminates the need for a sulfuric acid production plant, as the bacteria oxidize sulfur within the leaching heap. The results presented in this paper demonstrate comparable efficiencies between bioleaching and chemical leaching with sulfuric acid for nickel extraction, underscoring the importance of ferrous iron in enhancing leaching efficiency.