氧化亚铁硫杆菌对黄铁矿的表生风化试验研究

Experimental study on the effects of Thiobacillus ferrooxidans on the supergenesis of pyrite under weathering conditions

为探讨矿山环境中生物因子和非生物因子对硫化物矿物风化分解的作用机制,用从安徽铜陵新桥矿区酸性废水中分离得到的氧化亚铁硫杆菌对含硫固废堆的风化条件进行实验室模拟,在一定初始pH值、温度、固液比、矿样粒径、无菌及有菌条件下开展黄铁矿的生物氧化动力学试验,检测pH值、Eh值,及Fe^3＋、Fe^2＋、SO2^4-等离子的浓度。结果表明,在初始pH值为1.5、温度为30℃、矿样粒径为124~178μm、固液比为1∶100（g∶mL）的条件下,实验室风化模拟15 d后,有菌氧化体系黄铁矿氧化速率分别为空白基和空白矿氧化体系的5.8、6.5倍。低pH值能够加速黄铁矿的生物风化速率;微生物在其适宜的生长温度下,是加速黄铁矿氧化速率的重要因素;矿浆浓度对黄铁矿氧化速率的影响表现在风化中后期;在有菌、无菌反应体系中,粒径较小如124-178μm时Eh上升值和SO24-生成浓度都是最大的。

This paper is aimed at introducing our experimental research into the interactive mechanism of the microorganisms and abiotic components in the mining surroundings under the sulfide-mineral weathering conditions.In the paper,we have cultured a strain of T.f.（short for Thiobacillus ferrooxidans） isolated from the acid mining-drainage（AMD） and the mineral pyrite from the tailings of Xinqiao Mine,Tongling City,Anhui,in hoping to explore the bio-oxidation effects of the pyrite.For our research purpose,we have set up different appropriate initial values,such as those of the initial pH,temperature,solid-liquid ratio,and the particle sizes to compare the difference between the abiotic oxidation and bio-oxidation of pyrite.And,then,we have done abiotic oxidation and bio-oxidation kinetics experiments,intending to confirm the effects of the above said values on the oxidation of the pyrite.There have actually been found three kinds of immersing systems,the 90 mL enhanced sterilization of 9K medium;the 10 mL T.f.inocula immersed mineral pyrite（1 g） in the ＂ bacteria reaction system＂;and the 100 mL enhanced sterilization of 9K medium immersed mineral pyrite（1 g） in the ＂ blank medium reaction system＂;100 mL sterilized water immersed mineral pyrite（1 g） in the ＂blank core samples of the reaction system＂.All the above immersion experiments have been implemented in the 250 mL conical flasks.In addition,regular measurements of the contents of the ions,such as those of Fe3＋,Fe2＋,SO2-4 and pH,Eh were done in the process of the experiments.The results of the above said series of experiments prove that,under the oxidized conditions with the pH value of 1.5 and the temperature of 30 ℃,the particle sizes are kept within 124-178 μm,and the solid-liquid ratio remains in a ratio of 1：100（g：mL）.And,what is more important,15 days later,when the weathering experiment was over,the pyrite＇s oxidation rate of the ＂bacteria reaction system＂ turned out increased by 5.8 times as fast as the ＂ blank medium reaction system＂ and by 6.5 times as fast as the ＂blank core samples of the reaction system＂.Besides,the bio-oxidation rate of the pyrite has been found accelerated by the low pH value.Moreover,the increase of the appropriate temperature of the bacteria also plays a very important role in promoting the bio-oxidation rate of pyrite.Moreover,the pulp density proves to be able to affect the pyrite＇s oxidation rate at later oxidation stages.Thus,it can be expected that the concentration of SO2-4 and Eh value would be promoted to the highest under the lower particle size,such as 124-178 μm in different reaction systems.