矽卡岩型钼矿石表生氧化及辉钼矿微生物氧化作用初探

发布时间：2018-05-05 20:10

本文选题：辉钼矿 + 风化　；参考：《南京大学》2017年硕士论文

【摘要】：尾矿由于目标矿物组分含量较低而无法用于生产,常被作为废弃物堆积在矿山附近。这不仅占用了大量土地资源,尾矿风化造成的重金属元素迁移还会导致环境污染。中国是世界钼矿床数目较多的国家,钼矿床分布较广,钼尾矿风化过程中钼元素释放带来严重的环境危害。辉钼矿为主要含钼矿物,研究其风化过程对于探究尾矿中钼元素在表生环境中的迁移有重要意义。微生物-矿物相互作用影响着多种元素的表生地球化学过程,嗜酸性氧化亚铁硫杆菌(Acidithiobacillus ferrooxidans,以下简称A.ferrooxidans)是硫化物矿山具有代表性的一种微生物,微生物与金属硫化物相互作用是形成酸性矿山排水的重要原因,自然界中二者的相互作用有重要的环境意义和资源利用价值。在矽卡岩型钼矿床中,辉钼矿为主要的金属硫化物矿物,尾矿中微生物对于辉钼矿氧化及钼元素迁移具有重要作用,查明辉钼矿与微生物的相互作用机理对于钼污染的防治有理论意义。本文对钼矿石风化样品进行了系统的矿物学研究,利用XRD、SEM/EDS、DRS等分析手段,通过对风化成因次生矿物的种类、形态和成分差异进行分析,探讨了次生矿物的形成机制以及辉钼矿氧化过程中Mo的赋存和迁移形式,进而评估其对环境的影响。在此基础上,选取A.ferraoxidans与辉钼矿的进行模拟实验,实验中设置了含铁有菌组和含铁无菌组、无铁有菌组和无铁无菌组对照体系,其中含铁有菌组分别以FeSO4和黄铁矿作为不同的铁来源。通过ICP-OES、分光光度法等检测了实验体系溶液中离子浓度变化,使用扫描电镜及能潜分析了生物氧化后辉钼矿与黄铁矿的表面特征及形成的次生沉淀,探讨微生物氧化辉钼矿的机理以及初始不同来源铁离子对这一过程的影响。论文通过对河南南泥湖自然辉钼矿矿石在氧化过程中矿物变化的观察和辉钼矿与微生物相互作用实验研究得到以下认识得到以下认识:(1)南泥湖钼矿床中矿石原生矿物主要包括辉钼矿、方解石、黄铁矿,自然风化过程中主要形成钼钙矿、石膏、赤铁矿、针铁矿等次生矿物,未见铁钼华等常见含钼次生矿物。辉钼矿在风化过程中发生破碎、卷曲,辉钼矿表面结构的物理变化促进了其氧化过程。观察发现,与不同矿物接触界面,辉钼矿氧化形成的次生矿物有明显差异,钼矿石中辉钼矿风化产物受控于原生矿物组合形式,尤其是与辉钼矿相邻矿物对辉钼矿氧化产物影响较大。在辉钼矿与方解石接触处,主要生成石膏和钼钙矿,钼钙矿为半自形,2 μn左右,这说明方解石溶解消耗硫化物氧化产生的H+,提高了局部位置的pH,有利于钼钙矿和石膏沉淀;与黄铁矿接触处,主要生成赤铁矿、针铁矿,铁氧化物吸附重金属元素Mo。通过归纳前人含Mo、Fe、Ca矿物形成的Eh-pH条件得到不同条件下含辉钼矿钼矿石的风化产物序列,在中性环境中,Mo会被固定在钼钙矿或吸附在铁氧化物表面,由此减少重金属的释放进而降低对环境的污染危害。样品中发现了菌丝及真菌孢子类物质,说明微生物在钥矿石风化的过程中起到一定的作用。(2)模拟实验结果表明,以FeS04为初始铁来源的有菌组Mo溶出量显著高于以黄铁矿为初始铁来源的有菌组,Mo溶出量最低的为无铁有菌组;以黄铁矿为初始铁来源的有菌组,A.ferrooxidans倾向于附着在黄铁矿表面,黄铁矿表面形成明显的侵蚀坑;含铁有菌组生成的次生沉淀主要为铁硫酸盐、磷酸铁和石膏,有少量钼酸根吸附于铁硫酸盐和磷酸铁矿物表面,无铁有菌组有少量石膏生成。在矿石氧化过程中,辉钼矿微生物氧化程度和氧化产物受实验体系中Fe(Ⅱ)含量控制,体系中初始铁的存在有利于A.ferrooxidans的生长及体系氧化还原电位的提升,这为辉钼矿氧化创造了有利的化学环境。A.ferrooxidans对辉钼矿的氧化以间接作用为主,溶液中的Fe2+被A.ferrooxidans氧化为Fe3+,Fe3+氧化辉钼矿。在黄铁矿存在的情况下,黄铁矿会与辉钼矿形成竞争氧化关系。
[Abstract]:Tailing can not be used for production because of the low content of the target mineral composition. It is often accumulated as a waste in the vicinity of the mine. This not only occupies a large amount of land resources, but also leads to environmental pollution caused by the weathering of tailings. China is a country with a large number of molybdenum deposits in the world. Molybdenum deposits are widely distributed, and molybdenum tailing is weathered over. The release of Cheng Zhongmu elements has brought serious environmental hazards. Molybdenite is a major molybdenum bearing mineral. The study of its weathering process is of great significance for exploring the migration of molybdenum elements in the epigenetic environment. Microbiological interaction affects the surface geochemical processes of various elements, Acidithiobacillus Ferrooxidans, hereinafter referred to as A.ferrooxidans) is a representative kind of microorganism in sulfide mines. The interaction of microbes and metallic sulphides is an important reason for the formation of drainage in acid mines. The interaction of the two in nature has important environmental significance and resource utilization value. In the skarn molybdenum ore bed, molybdenite is the main source. The microorganism in tailings plays an important role in the oxidation of molybdenite and the migration of molybdenum elements in the tailings, and the mechanism of the interaction between molybdenite and microorganism is of theoretical significance to the prevention and control of molybdenum pollution. The systematic mineralogical study of the weathered molybdenum ore samples has been carried out in this paper by means of XRD, SEM/EDS, DRS and so on. The types, forms and components of secondary minerals of weathering origin are analyzed, the formation mechanism of secondary minerals and the occurrence and migration of Mo in the oxidation process of Molybdenite are discussed, and then the influence of the minerals on the environment is evaluated. On this basis, the simulation experiments of A.ferraoxidans and molybdenite are selected and the iron containing bacteria are set up in the experiment. The group and iron bearing aseptic group, the iron free group and the iron free aseptic group control system, including the iron containing bacteria group with FeSO4 and pyrite as different iron sources. The ion concentration changes in the experimental system solution were detected by ICP-OES, spectrophotometry and so on. Scanning electron microscope and potential analysis were used to analyze the table of molybdenite and pyrite after biological oxidation. The mechanism of microbial oxidation of molybdenite and the influence of the initial different sources of iron ions on this process are discussed. The following understanding is obtained through the observation of the mineral changes in the oxidation process of the ore of the natural molybdenite in the Henan South mud lake and the experimental study of the interaction between the molybdenite and the microorganism. (1) the primary ore minerals in the Mo deposit of the nanohu lake mainly include molybdenite, calcite and pyrite, which mainly form secondary minerals such as molybdenum calcite, gypsum, hematite and goethite, and no common molybdenum secondary minerals, such as iron, molybdenum and other minerals. In the process of wind, molybdenite is broken, curled, and the physical changes of the surface structure of Molybdenite are changed. It has been found that the oxidation process has been promoted. It is found that the secondary minerals formed by the oxidation of Molybdenite are obviously different from the contact interfaces of different minerals. The weathering products of Molybdenite in molybdenum ore are controlled by the combination of primary minerals, especially with the adjacent minerals of molybdenite, which have great influence on the oxidation products of molybdenite. The main contact of molybdenite and calcite is mainly at the contact of molybdenite and calcite. Gypsum and molybdenum calcite are produced, and the molybdenum calcite is half self shape and about 2 mu n. This indicates that calcite dissolves the H+ produced by the oxidation of sulfide, improves the pH of the local position, is beneficial to the precipitation of molybdenum calcite and gypsum, and mainly produces hematite, goethite and ferric oxide adsorbed heavy metal elements Mo. by inducing the predecessors containing Mo, Fe, Ca ore. The Eh-pH conditions formed under different conditions include the sequence of weathering products of Molybdenite molybdenum ore in different conditions. In the neutral environment, Mo will be fixed on the molybdenum calcite or adsorbed on the iron oxide surface, thereby reducing the release of heavy metals and reducing the pollution damage to the environment. The weathering process of key ore plays a certain role. (2) the results of simulation experiments show that the amount of Mo dissolution with FeS04 as the initial iron source is significantly higher than that of pyrite as the initial iron source, and the lowest dissolution rate of Mo is iron free group; with pyrite as the initial iron source, the A.ferrooxidans tends to attach to yellow. The surface of iron ore formed an obvious erosion pit on the surface of pyrite, and the secondary precipitates formed by the iron containing bacteria group were mainly iron sulfate, iron phosphate and gypsum, and a small amount of molybdate was adsorbed on the surface of iron sulfate and iron phosphate, and a small amount of gypsum produced in the iron free group. The substance is controlled by the content of Fe (II) in the experimental system. The existence of the initial iron in the system is beneficial to the growth of A.ferrooxidans and the improvement of the redox potential of the system. This creates a favorable chemical environment for the oxidation of Molybdenite by.A.ferrooxidans, and the Fe2+ in the solution is oxidized to Fe3+, Fe3+ in the solution, Fe3+. Oxidized pyrite. When pyrite exists, pyrite will form competitive oxidation relationship with molybdenite.

【学位授予单位】：南京大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P618.65

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