本文選題：輝鉬礦 + 風化��； 參考：《南京大學》2017年碩士論文

【摘要】：尾礦由于目標礦物組分含量較低而無法用于生產(chǎn),常被作為廢棄物堆積在礦山附近。這不僅占用了大量土地資源,尾礦風化造成的重金屬元素遷移還會導(dǎo)致環(huán)境污染。中國是世界鉬礦床數(shù)目較多的國家,鉬礦床分布較廣,鉬尾礦風化過程中鉬元素釋放帶來嚴重的環(huán)境危害。輝鉬礦為主要含鉬礦物,研究其風化過程對于探究尾礦中鉬元素在表生環(huán)境中的遷移有重要意義。微生物-礦物相互作用影響著多種元素的表生地球化學過程,嗜酸性氧化亞鐵硫桿菌(Acidithiobacillus ferrooxidans,以下簡稱A.ferrooxidans)是硫化物礦山具有代表性的一種微生物,微生物與金屬硫化物相互作用是形成酸性礦山排水的重要原因,自然界中二者的相互作用有重要的環(huán)境意義和資源利用價值。在矽卡巖型鉬礦床中,輝鉬礦為主要的金屬硫化物礦物,尾礦中微生物對于輝鉬礦氧化及鉬元素遷移具有重要作用,查明輝鉬礦與微生物的相互作用機理對于鉬污染的防治有理論意義。本文對鉬礦石風化樣品進行了系統(tǒng)的礦物學研究,利用XRD、SEM/EDS、DRS等分析手段,通過對風化成因次生礦物的種類、形態(tài)和成分差異進行分析,探討了次生礦物的形成機制以及輝鉬礦氧化過程中Mo的賦存和遷移形式,進而評估其對環(huán)境的影響。在此基礎(chǔ)上,選取A.ferraoxidans與輝鉬礦的進行模擬實驗,實驗中設(shè)置了含鐵有菌組和含鐵無菌組、無鐵有菌組和無鐵無菌組對照體系,其中含鐵有菌組分別以FeSO4和黃鐵礦作為不同的鐵來源。通過ICP-OES、分光光度法等檢測了實驗體系溶液中離子濃度變化,使用掃描電鏡及能潛分析了生物氧化后輝鉬礦與黃鐵礦的表面特征及形成的次生沉淀,探討微生物氧化輝鉬礦的機理以及初始不同來源鐵離子對這一過程的影響。論文通過對河南南泥湖自然輝鉬礦礦石在氧化過程中礦物變化的觀察和輝鉬礦與微生物相互作用實驗研究得到以下認識得到以下認識:(1)南泥湖鉬礦床中礦石原生礦物主要包括輝鉬礦、方解石、黃鐵礦,自然風化過程中主要形成鉬鈣礦、石膏、赤鐵礦、針鐵礦等次生礦物,未見鐵鉬華等常見含鉬次生礦物。輝鉬礦在風化過程中發(fā)生破碎、卷曲,輝鉬礦表面結(jié)構(gòu)的物理變化促進了其氧化過程。觀察發(fā)現(xiàn),與不同礦物接觸界面,輝鉬礦氧化形成的次生礦物有明顯差異,鉬礦石中輝鉬礦風化產(chǎn)物受控于原生礦物組合形式,尤其是與輝鉬礦相鄰礦物對輝鉬礦氧化產(chǎn)物影響較大。在輝鉬礦與方解石接觸處,主要生成石膏和鉬鈣礦,鉬鈣礦為半自形,2 μn左右,這說明方解石溶解消耗硫化物氧化產(chǎn)生的H+,提高了局部位置的pH,有利于鉬鈣礦和石膏沉淀;與黃鐵礦接觸處,主要生成赤鐵礦、針鐵礦,鐵氧化物吸附重金屬元素Mo。通過歸納前人含Mo、Fe、Ca礦物形成的Eh-pH條件得到不同條件下含輝鉬礦鉬礦石的風化產(chǎn)物序列,在中性環(huán)境中,Mo會被固定在鉬鈣礦或吸附在鐵氧化物表面,由此減少重金屬的釋放進而降低對環(huán)境的污染危害。樣品中發(fā)現(xiàn)了菌絲及真菌孢子類物質(zhì),說明微生物在鑰礦石風化的過程中起到一定的作用。(2)模擬實驗結(jié)果表明,以FeS04為初始鐵來源的有菌組Mo溶出量顯著高于以黃鐵礦為初始鐵來源的有菌組,Mo溶出量最低的為無鐵有菌組;以黃鐵礦為初始鐵來源的有菌組,A.ferrooxidans傾向于附著在黃鐵礦表面,黃鐵礦表面形成明顯的侵蝕坑;含鐵有菌組生成的次生沉淀主要為鐵硫酸鹽、磷酸鐵和石膏,有少量鉬酸根吸附于鐵硫酸鹽和磷酸鐵礦物表面,無鐵有菌組有少量石膏生成。在礦石氧化過程中,輝鉬礦微生物氧化程度和氧化產(chǎn)物受實驗體系中Fe(Ⅱ)含量控制,體系中初始鐵的存在有利于A.ferrooxidans的生長及體系氧化還原電位的提升,這為輝鉬礦氧化創(chuàng)造了有利的化學環(huán)境。A.ferrooxidans對輝鉬礦的氧化以間接作用為主,溶液中的Fe2+被A.ferrooxidans氧化為Fe3+,Fe3+氧化輝鉬礦。在黃鐵礦存在的情況下,黃鐵礦會與輝鉬礦形成競爭氧化關(guān)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.

【學位授予單位】：南京大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：P618.65

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