Electrochemical Applications in Metal Bioleaching

Abstract

Biohydrometallurgy comprises the recovery of metals by biologically catalyzed metal dissolution from solids in an aqueous solution. The application of this kind of bioprocessing is described as "biomining," referring to either bioleaching or biooxidation of sulfide metal ores. Acidophilic iron- and sulfur-oxidizing microorganisms are the key to successful biomining. However, minerals such as primary copper sulfides are recalcitrant to dissolution, which is probably due to their semiconductivity or passivation effects, resulting in low reaction rates. Thus, further improvements of the bioleaching process are recommendable. Mineral sulfide dissolution is based on redox reactions and can be accomplished by electrochemical technologies. The impact of electrochemistry on biohydrometallurgy affects processing as well as analytics. Electroanalysis is still the most widely used electrochemical application in mineralogical research. Electrochemical processing can contribute to bioleaching in two ways. The first approach is the coupling of a mineral sulfide to a galvanic partner or electrocatalyst (spontaneous electron transfer). This approach requires only low energy consumption and takes place without technical installations by the addition of higher redox potential minerals (mostly pyrite), carbonic material, or electrocatalytic ions (mostly silver ions). Consequently, the processed mineral (often chalcopyrite) is preferentially dissolved. The second approach is the application of electrolytic bioreactors (controlled electron transfer). The electrochemical regulation of electrolyte properties by such reactors has found most consideration. It implies the regulation of ferrous and ferric ion ratios, which further results in optimized solution redox potential, less passivation effects, and promotion of microbial activity. However, many questions remain open and it is recommended that reactor and electrode designs are improved, with the aim of finding options for simplified biohydrometallurgical processing. This chapter focuses on metal sulfide dissolution via bioleaching and does not include other biohydrometallurgical processes such as microbial metal recovery from solution.

Insight Into Interactions of Thermoacidophilic Archaea With Elemental Sulfur: Biofilm Dynamics and EPS Analysis

“…Various sulfur intermediates are formed through either thiosulfate or polysulfide pathways during MS dissolution (Vera et al, 2013). As one of the major intermediates in the polysulfide pathway (Sand et al, 2001), elemental sulfur (S 0 ) may form passive layers, which are chemically inert and may hinder further chemical reactions on the solid’s surface, thus preventing further MS dissolution (Rodrıguez et al, 2003; Tanne and Schippers, 2017). Subsequently, metal leaching is hindered.…”

Copper extraction from low-grade chalcopyrite in a bioleaching column assisted by bioelectrochemical system

“…In current mining industry, attention has been given to bioleaching due to the processes of it was clean (Ma et al, 2021;Sun et al, 2021). Bioleaching applies microorganisms and their secretions (mainly extracellular polymeric substances, EPS) to recover value-metals from minerals at mild conditions (Tanne & Schippers, 2019). However, the copper extraction e ciency in chalcopyrite bioleaching process is low due to some reasons: high lattice energy of chalcopyrite (Wang, 2005;Zhang et al, 2016), and easy to form passivation layers in the bioleaching process.…”

“…Bioleaching as an intersection of multiple disciplines is well suited to implement electrochemical approaches for the optimization of metal leaching and recovery (Kaksonen et al, 2020;Tanne & Schippers, 2019). The feasibility of MFCs to assist in the bioleaching of chalcopyrite concentrates has been demonstrated (Huang et al, 2019).…”

Influence of ore grade and mineral medium on chalcopyrite bioleaching with mixed microbial consortia

“…Chalcopyrite (CuFeS 2 ) is the most abundant copper ore; it is estimated that 80% of worldwide copper reserves are formed by low‐grade chalcopyrite deposits 1 . However, this mineral source is especially recalcitrant and copper extraction by hydrometallurgical processes is complex and expensive, especially from low‐grade ores 2 …”