The catalytic activity of biological seeds and Acidithiobacillus ferrooxidans on the process of ammonium jarosite

Ferric iron that commonly exists in leaching solution needs to be removed before the recovery of copper bioleaching using methods such as jarosite seed. The objective of this study was to investigate in the catalytic performance of biological seeds and Acidithiobacillus ferrooxidans in the process of jarosite formation via biosynthesis process.

Acidithiobacillus ferrooxidans was first grown in 9K medium. Jarosite seeds were synthesized using this bacterium. Then the effect of biological activity of different seeds (5, 10 g/L) on jarosite formation was investigated. The type of jarosites synthesized was identified by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM) analysis. Meantime, the morphologies of jarosite crystals were studied.

The FTIR and XRD results showed that biosynthetic jarosite seeds is ammonium jarosite type. The amount of jarosite increased with increasing seed concentration and the induction time of precipitation decreased. The pH and Eh of culture medium with increasing seed decreased. Bacterial growth also decreased in the presence of jarosite seeds compared to medium without biological seeds. According to the results of SEM, The morphologies of ammonium jarosite crystals were significantly affected by the jarosite seeds. The jarosite crystals were precipitated with the presence of seeds had smooth, uniform and larger surface than non- seeding jarosite.

The results showed that the precipitation process of jarosite is more complete with biological seeds.  The results of this study can improve the efficiency of iron removal process in copper bioleaching and reduce production costs.