Huan He

Comparison Analysis of Coal Biodesulfurization and Coal's Pyrite Bioleaching with Acidithiobacillus ferrooxidans

Acidithiobacillus ferrooxidans (A. ferrooxidans) was applied in coal biodesulfurization and coals pyrite bioleaching. The result showed that A. ferrooxidans had significantly promoted the biodesulfurization of coal and bioleaching of coals pyrite. After 16 days of processing, the total sulfur removal rate of coal was 50.6%, and among them the removal of pyritic sulfur was up to 69.9%. On the contrary, after 12 days of processing, the coals pyrite bioleaching rate was 72.0%. SEM micrographs showed that the major pyrite forms in coal were massive and veinlets. It seems that the bacteria took priority to remove the massive pyrite. The sulfur relative contents analysis from XANES showed that the elemental sulfur (28.32%) and jarosite (18.99%) were accumulated in the biotreated residual coal. However, XRD and XANES spectra of residual pyrite indicated that the sulfur components were mainly composed of pyrite (49.34%) and elemental sulfur (50.72%) but no other sulfur contents were detected. Based on the present results, we speculated that the pyrite forms in coal might affect sulfur biooxidation process.

Sulfur Species Investigation in Extra- and Intracellular Sulfur Globules of Acidithiobacillus ferrooxidans and Acidithiobacillus caldus

The sulfur chemical speciation in extracellular and intracellular sulfur globules of Acidithiobacillus ferrooxidans and Acidithiobacillus caldus were investigated with an integrated approach including scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy and sulfur K-edge X-ray absorption near edge structure spectroscopy (XANES). The results indicated that both strains can accumulate extracellular sulfur globules when grown on thiosulfate, and the major sulfur chemical speciation of which were S8 for A. ferrooxidans and mixture of ring sulfur and polythionate for A. caldus, respectively. In contrast, A. ferrooxidans can accumulate both linear sulfur and S8 internally when grown with sulfur powder and thiosulfate, whereas A. caldus did not accumulate intracellular sulfur globules. In addition, the fitted results of sulfur K-edge XANES spectra indicated that the reduced glutathione (containing thiols groups) were involved in sulfur bio-oxidation of both strains and the tetrathionate were the intermediate products during thiosulfate metabolism by two strains.

A study on soil basic characteristics, main microbial flora and typical metal fraction surrounding coal gangue dump in Xiangtan Hunan Province, south of China

During the coal ore mining and utilization process, coal and its associated minerals have been discharged as coal gangue. Upon interacting with the water, air and microbial oxidation, the harmful metals and sulfides in coal gangue will cause serious pollution. In present work, the basic chemical characteristics, main microbial flora and typical metal speciation of the soil around coal gangue dump in Liejiaqiao coal mine, xiangtan mining area, Hunan province south of China were analyzed with several methods including XRF, XRD, microbial plate culture count and Tessier’s sequential extraction scheme. Correlation, cluster and principal component analysis (PCA) were used to estimate the possible main factors of coal gangue dump’s effect on surrounding soil and their correlation with microbial flora. Research results showed that the soil surrounding the coal gangue dump had low pH and microbial abundance (including bacteria, fungi and actinomycete). The soil samples contained high levels of metals especially for Mn, Fe and Cr. Tessier’s sequential extraction results showed that Fe, Mn and Cr were mainly associated residual fraction. Risk assessment revealed that Fe and Cr had lower risk than Mn to the surrounding environment. Based on PCA and cluster analysis results, the obtained ten samples can be divided into three groups. Among of them, mobile fraction of metals, microbial abundance could be the main factor reflecting the soil pollution around the coal gangue dump. Furthermore, correlation analysis showed that the abundance of bacteria and actinomycete had significant relationship (at 0.05 levels) with mobility factor of Fe and pH condition of the soil samples, respectively.

Quantitative Measurement of Coal Bio-solubilization by Ultraviolet-visible Spectroscopy

This study developed mathematic models to convert ultraviolet-visible absorbance (UV/Vis) of bio-solublized coal to conversion ratios. By a mathematic regression method, the results showed that they had strong linear relationships. The highest correlation coefficient (0.99531) of the linear relationship between UV/Vis absorbance and coal bio-solubilization ratios was obtained at the wavelength of 513 nm. The high correlation coefficient further indicated that the use of UV/Vis with the proposed mathematic model would be an easier, quicker, and more accurate measurement, as compared with the conventional measurement of weighing coal loss after bio-solubilization.

Thermal effect on fluorine emission in coal and clay minerals

Fluorine in coal is important because of not only its association with indicators of mineralization, but also environmental concerns relevant to the health of plants, animals and humans. In order to analyze the fluorine emission characteristics, this paper summarizes the laboratory data from a number of Chinese literatures of fluorine emission of coal and clay minerals for high-temperature heating. The range of temperature to which specimens have been exposed is room temperature to 1200xa0°C. The variation of fluorine emission has a significant increase with increasing temperature between the ranges 400–1200xa0°C, especially above 600xa0°C. Besides, environmental humidity has obvious influence on fluorine releasing.

Microbial consortium in a non-production biogas coal mine of eastern China and its methane generation from lignite

ABSTRACT A coal bed water in Zhaolou coal mine of eastern China contained abundant microbial consortia, which could convert Baiyinhua native lignite to biogenic methane. The major microbes in coal bed water were bacteria (88%) including Proteobacteria and Firmicutes, and the rest of it were assigned to Methanobacterium. Methane generation rate with this microbial consortium was up to 72 μmol/g coal in 28 d culture. After treatments with the enriched culture, the ash, volatility contents, and hydrophobicity of residual lignite decreased, while its active functional groups containing oxygen and hydrogen increased.