The improved sparger enhances bioleaching of arsenic-bearing gold concentrate in a stirred tank

Bioleaching is frequently applied to low - grade ores, and mixed - strain leaching can be influenced by factors such as temperature and substrates. This study compared the cooperative leaching effects of mesophilic and thermophilic strains, including Leptospirillum ferrooxidans (L. f), Acidithiobacillus caldus (A. c), and Sulfobacillus thermosulfidooxidans (S. t). An efficient strain combination of (L. f + A. c): S. t = 1:1 was identified. Subsequently, the original sparger was replaced with a nano - aeration pipe (NAP) to investigate its impact. Results indicated that NAP considerably elevated the oxygen uptake rate (OUR) and volumetric mass transfer coefficient (kLa) within the reaction system. Moreover, by analyzing the extracellular polymeric substances (EPS) content in leaching samples and assessing the microbial community, it was shown that the improved sparger, namely NAP, increased EPS content and altered the dominant bacterial groups in bioleaching. Leaching efficiency rose by 3.61 %, while daily energy consumption fell by 1.59 %. Scanning electron microscopy also confirmed that NAP enhanced microbial leaching. This study not only improves leaching efficiency and demonstrates economic potential but also offers a novel perspective for optimizing stirred - tank technology in bioleaching.