A Review of the Application of Ultrasound in Bioleaching and Insights from Sonication in (Bio)Chemical Processes

Abstract

Chemical and biological leaching is practiced on a commercial scale for the mining of metals from ores. Although bioleaching is an environmentally-friendly alternative to chemical leaching, one of the principal shortcomings is the slow rate of leaching which needs to be addressed. The application of ultrasound in bioleaching, termed sonobioleaching, is a technique which has been reported to increase the rate and extent of metal extraction. This article reviews efforts made in the field of sonobioleaching. Since bioleaching is effectively a biological and chemical process, the effects of sonication on chemical leaching/reactions and biological processes are also reviewed. Although sonication increases metal extraction by increasing the metabolite production and enhanced mixing at a micro scale, research is limited in terms of the microorganisms explored. This paper highlights some shortcomings and limitations of existing techniques, and proposes directions for future research.

Selective metal extraction by biologically produced siderophores during bioleaching from low-grade primary and secondary mineral resources

“…No metals were extracted in the growth media control, indicating that metals leached were through a combination of siderophore and/ or physiochemical modifications. Whilst sonochemical leaching has been demonstrated to impact (bio)physiochemical parameters and improve (bio)leaching processes, no significant impact on metal extraction was observed in our experiments (p = 0.250) 50 . Aside from copper, a slightly poorer bioleaching performance in the presence of residual Pseudomonas cells was observed.…”

Ultrasound-assisted leaching of vanadium from fly ash using lemon juice organic acids

“…This was due to the production of hydroxyl radicals induced by ultrasound. 32 After 80 min, due to the breakdown of the diffusion layer and the consumption of hydroxyl radicals, Eh decreased to 140 mV. In this case, the breaking of the oily layer occurred 30 min earlier than the previous case because ultrasound accelerated the breaking.…”

An Improvement on Selective Separation by Applying Ultrasound to Rougher and Re-Cleaner Stages of Copper Flotation

“…In heterogeneous solid-liquid reactions, ultrasound increases the reactivity of metal powders by as much as 100,000-fold [3]. Numerous studies have shown the application of ultrasonic frequencies (>20 kHz), known as ultra-sonication, to mineral beneficiation particularly in the interface science [4], biochemistry [5], flotation [6][7][8][9], and hydrometallurgy [10,11].…”