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题名	含砷硫化物金矿细菌氧化脱砷机理及氰化提金研究
作者	向兰
学位类别	硕士
答辩日期	1992-06-30
授予单位	中国科学院研究生院
授予地点	北京
导师	柯家骏
学位专业	化学工艺
中文摘要	含砷的硫化物金矿是世界公认的难处理金矿。作为处理这类矿石的一种有效方法，细菌氧化脱砷方法具有金银回收率高、投资费用较少和无环境污染等优点，近年来已在国外得到工业应用，现正引起国内冶金界的重视。目前，有关细菌氧化脱砷的工作大多属于工艺条件试验，对其反应机理及规律性的研究报道尚少。为在我国早日开发应用难处理金矿细菌氧化脱砷的新工艺，本工作紧密结合实际细菌氧化脱砷过程，用动力学、生物学和物理检测方法，开展有关的应用基础研究。首先，本工作选出耐能力强和具有分解硫化矿能力的氧化亚铁硫杆菌8＃菌株作为实验用菌，考察了几种较纯的含砷硫化矿物和黄铁矿进行细菌氧化浸出的行为。结果表明，该菌株能有效地氧化毒砂和黄铁矿，对砷黝铜矿、雄黄和雌黄的作用相对较小，氧化分解的次序为：毒砂 ＞ 黄铁矿 ＞ 砷黝铜矿 ＞ 雄黄和雌黄。细菌氧化动力学研究表明，在本实验范围内毒砂的细菌氧化是以化学反应为主、兼有细菌作用的复杂多相反应过程。整个细菌氧化过程可用表面化学反就控制的动力学方程：1 - (1 - a)~(1/3) = kt + b 描述。同时，X 射线衍射分析结果表明，该反应过程有 FeAsO_4·2H_2O 和 a - S°生成，Fe~(3+) 与毒砂之间化学反就的结果是导致 a - S°形成的主要原因之一。通过研究细菌氧化含砷硫化矿物和黄铁矿的过程，包括细菌在矿物表面的作用方式、细菌在溶液中的作用以及矿物组成和结构对细菌浸蚀行为的影响等，进一步加深了对细菌浸蚀行为的认识。对矿石抛光面实验的结果表明，细菌对黄铁矿的浸蚀作用在晶格缺陷处和解理面方向均可进行；而对毒砂的浸蚀作用则只在缺陷较为显处选择性进行，显示出细菌对黄铁矿的直接作用更为明显。浮选药剂对细菌生长速率影响结果表明，不同的浮选药剂其影响程度有差异。乙基黄药对本实验所用 8＃ 菌株的抑制作用最大，当矿浆中乙基黄药浓度超过 10.0 mg/t 时，细菌生长明显受到抑制；丁基铵黑药也有影响；而丁基黄药、异丁基黄药和 2 号油起泡剂的抑制作用则较小。对湖南龙山含砷的金锑精矿进行细菌浸出的实验结果进一步表明，细菌生长情况和脱砷效果均与浮选药剂的关系密切。对吸附有乙基黄药较多的浮选金精矿，细菌浸出前应先进行预脱药处理，才能获得较好的细菌氧化脱砷效果。
英文摘要	Biooxidation of arsenic is considered as an effective method for pretreatment of refractory arsenic-bearing sulphide gold ores. Recently, this technique has been practised on an industrial scale in several countries, and increasing interest has also arisen in China. This process offers several advantages, including higher recovery of gold and silver, lower operating cost and less environmental pollution. Although many technological processes of biooxidation were reported, only limited work on the mechanistic aspect of biooxidation has been undertaken because of difficulties involved in the bioleaching process. The objective of this work is to study the mechanisms involved in the practical bioleaching process of arsenic using kinetic and biological methods as well as modern techniques of analysis and detection, so as to promote the application of biotechnology in the pretreatment of refractory gold ores. A strain of Thiobacillus ferrooxidans 8# which was isolated from the acidic water of an arsenopyrite mine is used in the experiments. This strain can tolerate higher concentration of arsenic ions and decompose sulphide ores effectively. The bioleaching behaviour of several arsenic-bearing sulphide ores and pyrite is studied. It is shown from the experimental results that the arsenopyrite and pyrite can be oxidized effectively by strain 8# while the effect of biooxidation on the tennantite, realgar and orpiment is weaker. The order of biooxidation extent is: arsenopyrite > pyrite > tennantite > realgar and orpiment. Under the experimental conditions, biooxidation of arsenopyrite is a complex heterogeneous process, the rate of which is determined by both the chemical reactions between Fe~(3+) and arsenopyrite and the activity of bacteria. The overall process can be represented by the following kinetic equation: 1 - (1 - a)~(1/3) = kt + b where a-extracted fraction of arsenic; t-time; k, b-constant. X-ray analysis of bioleaching residue reveals that FeAsO_4·2H_2O and a - S°are the reaction products. Research work also shows that the formation of a - S°is mainly due to the interreaction between Fe~(3+) and arsenopyrite. The influence of the generally used flotation agents on the growth of bacteria is studied. Experimental results indicate that the growth of bacteria is related seriously in the media containing ethyl xanthate more than 10.0 g/l. The order of toxicity of different flotation agents to Thiobacillus ferrooxidans is: ethyl xanthate > butyl ammonium aerofloat > butyl xanthate ≈ isobutyl xanthate ≈ frother No. 2 oil. Bioleaching pretreatment of arsenic and antimony-bearing gold concentrate shows that the growth of bacteria and the leaching of arsenic from ores are closely associated with the flotation agents adsorbed on the surface of the concentrates. Prior to bioleaching, the arsenic-bearing sulphide concentrates which contain considerable amount of ethyl xanthate should be rinsed with water to remove flotation agents, so as to get satisfactory removal of arsenic by bacteria.
语种	中文
公开日期	2013-10-31
页码	121
内容类型	学位论文
源URL	[http://ir.ipe.ac.cn/handle/122111/4668]
专题	过程工程研究所_研究所（批量导入）
推荐引用方式 GB/T 7714	向兰. 含砷硫化物金矿细菌氧化脱砷机理及氰化提金研究[D]. 北京. 中国科学院研究生院. 1992.

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