[1] Interface Regulation Enhances Chalcopyrite Bioleaching

• Aiming to address the challenges of low leaching rates and efficiencies in chalcopyrite bioleaching, research investigates: selecting of high-efficiency microbial strains, formation mechanisms of passivation layers during chalcopyrite leaching, and catalytic performance and mechanisms of surfactants.

  Key Research Findings:

  1. Isolation of Acidophilic Strain: An acidophilic Acidithiobacillus ferrooxidans strain, capable of cold-tolerant, effective bioleaching, was isolated from acidic mine waters at high altitudes. Genetic analysis was conducted, and the strain's 16S rDNA sequence has been submitted to NCBI.

  2. Passivation Layer Formation Mechanism: The primary chemical reactions involved in mesophilic chalcopyrite bioleaching were elucidated. Results showed that iron precipitates and elemental sulfur are the main contributors to chalcopyrite surface passivation, and the passivation layer formation process was modeled, comprising elemental sulfur-potassium jarosite-ammonium jarosite phases.

  3. Surfactant Structure-Performance Relationship: The relationship between surfactant molecular structure and catalytic efficiency was explored. Findings indicate that surfactants with ethoxy groups, without long alkyl chains, and with moderate carbon chain lengths (either polymeric or nonionic) significantly enhance chalcopyrite bioleaching. Key structural factors include molecular configuration and hydrophilic-lipophilic balance (HLB).

  4. Nonionic Surfactant Mechanisms: Varied mechanisms were observed among nonionic surfactants. While Triton X-100 itself lacks chalcopyrite leaching ability, it facilitates bioleaching by inducing bio-oxidation and decomposition of elemental sulfur intermediates. Polyethylene glycol (PEG) was found to improve chalcopyrite hydrophilicity, enhancing leaching depth and bacterial oxidation of sulfur, thus mitigating passivation.