Marine hydrogenous ferromanganese crust, an important metal resource in the future, has significant potential in various applications as a type of natural nano-structured material. By employing scanning electronic microscopy, nitrogen adsorption-desorption isotherm measurement, Xray fluorescence spectrometer and X-ray diffraction methods, the micro-structure, surface properties and chemical composition of several plate-like ferromanganese crusts sampled from the northwestern Pacific were investigated comprehensively. Although obvious differences were observed from different layers, the crust is a typical porous material with high specific surface area, unique pore structure and abundant transition elements. Furthermore, the performance of natural crust in desulfurization process was preliminarily tested in laboratory experiments. The suffur capacities of the crust are 13.1% and 18.1% at room temperature and 350 ℃, respectively. The crust can be used not only as a metal resource, but also as an environmental material.
LU Xiancai HOU Qingfeng LIU Xiandong YANG Kan WANG Rucheng LING Hongfei XU Shijin
In order to investigate the effect of Thiobacillusferrooxidans on the oxidation of pyrite, two parallel experiments, which employed H2SO4 solutions and acidic solutions inoculated with ThiobaciUus ferrooxidans, were designed and carried out at 30℃. The initial pH of the two solutions was adjusted to 2.5 by dropwise addition of concentrated sulphuric acid. The surfaces of pyrite before exposure to leaching solutions and after exposure to the H2SO4 solutions and acidic solutions inoculated with Thiobacillus ferrooxidans were observed by scanning electron microscopy （SEM）. There were a variety of erosion patterns by Thiobacillusferrooxidans on the bio-leached pyrite surfaces. A conclusion can be drawn that the oxidation of pyrite might have been caused by erosion of the surfaces. Attachment of the bacteria to pyrite surfaces resulted in erosion pits, leading to the oxidation of pyrite. It is possible that the direct mechanism plays the most important role in the oxidation of pyrite. The changes in iron ion concentrations of both the experimental solutions with time suggest that ThiobaciUus ferrooxidans can enhance greatly the oxidation of pyrite.
LU Jianjun LU Xiancai WANG Rucheng LI Juan ZHU Changjian GAO Jianfeng
