Papers by Keyword: Bioleaching Process

Abstract: An in situ characterization has been carried out for several active systems (sulfuric acid, ferric iron, 9k medium and bioleaching solutions) to investigate the bioleaching process of natural pyrite using electrochemical noise (ECN) technique. Spectral noise impedance spectra obtained from power spectral density (PSD) plots for the different systems were compared. It has been observed that the bioleaching system obtained the lowest noise resistance Rsn 0.101MΩ. The reaction mechanism was proposed based on experimental data analysis. The bioleaching process of natural pyrite has been identified as the main function of bio-battery reactions, which distinguishes from the chemical oxidation reaction for the ferric ion and 9k solutions.

Abstract: In this study, the effect of the mineral matter of Huadian (China) Oil Shale on the conversion of organic carbon of oil shale to shale oil. The bioleaching process is taken in a mixed culture of the lithotrophic bacteria Thiobacillus ferrooxidans(Tf). The aim of bioleaching process was to dissolve the inorganic matters and improve the shale oil yield. A series of temperature-programmed pyrolysis operation was performed with raw and bioleached oil shale to find the best retorting temperature, 500oC is the best temperature to retort the oil shale. The oil shale samples were detected by SEM, DG, Fischer assay test, the results show that the surface structure was significantly different from the raw sample, and the shale oil yield improved from 8.9% to 11.7%.

Abstract: Chalcopyrite bioleaching process using Acidithiobacillus ferrooxidans and a mixed culture of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans like bacterium was carried out. Two mineral particle sizes were evaluated, 200 and 325 Tyler mesh. The strains were adapted by gradually decreasing of the main energy sources and increasing in the mineral content. The experiments were performed in absence of ferrous sulphate and elemental sulfur. When the mixed culture was used, pH values were always over 2,1, indicating a probable passivation of Acidithiobacillus thiooxidans in the consortium. For both cultures, the Cu2+ dissolution occurred at relatively low redox potential values, around 400mV–450mV, while at high redox potential values, 550mV, chalcopyrite dissolution was inhibited. Copper lixiviation was around 40% for both tests. The Fourier Transform-Infrared spectra showed that the main oxidation phase is jarosite. The results showed that chalcopyrite oxidation is more dependent on the redox potential than particle size or type of culture used.