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Alternative TitleStudy on the Harmless Disposal of Arsenic Sulfide Residue Using Bioleaching Technology
Thesis Advisor张广积 ; 杨超
Degree Grantor中国科学院研究生院
Degree Discipline化学工程
Keyword生物浸出   硫化砷渣   臭葱石   中度嗜热西伯利亚硫杆菌(S.s)   嗜酸氧化亚铁硫杆菌(At.f)
Abstract随着我国有色金属冶炼行业的不断发展,含砷废渣日益增多,导致砷污染事件频发。如今,砷污染成为我国有色金属冶炼业必须面对的最棘手的问题。臭葱石因其低溶解度和高环境稳定性而成为国际公认的最佳固砷化合物。然而,目前臭葱石的合成是在高压釜中高温高压条件下进行。一些研究实现了在常压下低于100℃条件下水热合成臭葱石(Fe2AsO4?2H2O),但尚未工业应用。生物浸出技术因其成本低廉、工艺简单的优点,已经成功应用于低品位矿石回收有价金属。一些研究表明,含砷矿物的溶解浸出活性与天然臭葱石的形成密切相关。 本论文以铜砷滤饼为研究对象,使用嗜酸氧化亚铁硫杆菌(Acidthiobacillus ferrooxidans,At.ferrooxidans)和中度嗜热西伯利亚硫杆菌(Sulfobacillus sibiricu,S.sibiricu)作为菌株,对生物浸出铜砷滤饼的可行性进行了系统研究。考察了pH值、温度对铜和砷浸出效果的影响,研究了铁氧化菌浸出机理。结果表明,S.sibiricu菌浸出效果比At.ferrooxidans好;热酸预处理后在50℃、pH值为1.5的条件下,S.sibiricu菌浸出7天,砷浸出率达91.33%,铜浸出率达94.22%。 研究了生物氧化作用对砷酸铁结晶的影响,实验测定了晶种、初始pH和温度对结晶效果的影响。结果表明:添加晶种能够促进砷酸铁结晶的生成,而且增加晶种加入量能够加快砷的沉淀;细菌使Fe2+在较低温度下快速氧化生成Fe3+,Fe3+与AsO43-在晶种表面生长形成砷酸铁结晶(臭葱石),但如果Fe3+浓度增加过快,使溶液中过饱和度增加,容易产生无定形砷酸铁沉淀并附着于晶种表面,阻碍晶种的长大,不利于结晶的形成;初始pH过高也会造成无定型砷酸铁的生成,发现初始pH为1.5时更有利于砷酸铁结晶的形成。
Other AbstractWith the development of non-ferrous metallurgical industry in China, the emission of arsenic-containing sludge is increasing rapidly and results in frequent arsenic contamination accidents. Today, the arsenic pollution is becoming one of the most urgent issues which the Chinese non-ferrous metallurgical industry has to face. Scorodite is thought to be the best compound for arsenic fixation due to its low solubility and high environmental stability. However, the synthesis of scorodite has to be carried out in an autoclave under the condition of high temperature and pressure. Some researches showed that scorodite can be synthesized by a hydrothermal precipitation under the condition of atmopheric pressure and below 100℃, but has not yet been industrial applied. Bioleaching has been used in recovery of valuble metals from low-grade ores, for its low cost and simple process. Some studies showed that dissolution of arsenic-bearing mineral and formation of natural scorodite are very closely related with the bioleaching activity. In this study, the Cu-As-containing filter cake from copper smelting plant was bioleached with Acidithiobacillus ferrooxidans (At.ferrooxidans) and Sulfobacillus sibiricu (S.sibiricu) for testing the feasibility of dissolving the solid waste by a bioleaching process. The effects of pH and temperature on the bioleaching rates of Cu and As were investigated, and the bioleaching mechanism was studied. The results show that the leaching rate by S.sibiricu is higher than that by At.ferrooxidans and the optimum bioeaching conditions were as follows: temperature of 50℃ and pH value of 1.5. Under the conditions, the bioleaching ratio of As can reach 91.33% and that of Cu 94.22% in 7 d. The influence of biooxidation on the crystallization of ferric arsenic was studied. In the biooxidation experiments, the effects of crystal seeds, initial pH and temperature were investigated. It was found that the crystal seeds can promote the formation of crystals of scorodite, and with the increase of the amount of the additional seeds, the precipitation rate was improved. The bacteria can oxidize Fe2+ to Fe3+ rapidly at ambient temperature, and Fe3+ can react with AsO43- and form the crystal scorodite on the surface of the seeds. In some cases, faster oxidizing rates would lead to higher supersaturations and form the amorphous FeAsO4, which was attached on the surface of the seeds and hindered the crystallization. Higher initial pH results in formation of the amorphous FeAsO4 as well, and the experimental result shows that initial pH of 1.5 is the best for formation of the crystal scorodite.
Document Type学位论文
Recommended Citation
GB/T 7714
杜娟. 生物浸出技术对硫化砷废渣的无害化处理研究[D]. 中国科学院研究生院,2014.
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