本文選題：三合鋁土礦 + 礦物轉(zhuǎn)化��； 參考：《中國地質(zhì)大學(北京)》2015年碩士論文

【摘要】：桂西地區(qū)是我國鋁土礦的重要產(chǎn)地。三合鋁土礦區(qū)位于桂西的西南部,與周邊德保、那坡一帶的鋁土礦組成特大型鋁土礦田。桂西鋁土礦為典型的喀斯特型,包括二疊系沉積型鋁土礦和第四系堆積型鋁土礦兩種亞類。其中堆積型鋁土礦品位高、儲量大、易開采加工,是目前開發(fā)的主要對象。堆積型鋁土礦是沉積型鋁土礦經(jīng)抬升、破碎、風化,最后堆積于喀斯特洼地中形成。本文運用多種實驗測試和數(shù)據(jù)統(tǒng)計方法在礦物和元素尺度上詳細研究鋁土礦的演化過程。通過X射線衍射、電子探針對礦石的礦物組成和成分進行分析,結(jié)果顯示三合鋁土礦礦石的主要礦物組成為硬水鋁石、鮞綠泥石、銳鈦礦、黃鐵礦、鈦鐵礦、針鐵礦、高嶺石等。鋁土礦中礦物形態(tài)各異,各礦物組成呈混雜共生的狀態(tài)。在表生條件下,鋁土礦中的礦物都具有風化蝕變的特征,大多礦物都存在元素的混入或代換現(xiàn)象,礦物成分混雜。地球化學組分分析顯示三合鋁土礦的主要化學成分為Al2O3、Si O2、Fe2O3、Fe O、Ti O2、Mg O和H2O+。其它成分含量不足1%,鋁土礦的成熟度高。微量元素中Zr和Cr的含量很高。平均含量分別為867.93×10-6和792.16×10-6。除此之外,鋁土礦中元素Li、Ba、F、Nb、S、Sr、Zn和V的含量也較高,平均含量在100×10-6~40×10-6之間。其余元素Cs、Cu、Ga、Hf、Ni、Sc、Th和U的平均含量均在10×10-6~100×10-6之間。礦石中稀土總量較大,整體富集輕稀土。在原生的沉積型礦石在演化的過程中,首先受到水系對其淋濾的影響,此時礦石主要仍處于還原環(huán)境。裂隙經(jīng)過處的一些礦物首先遭受風化溶蝕,在礦物內(nèi)部形成溶蝕洞,一些元素被流水帶走,一些元素在礦石內(nèi)部發(fā)生各種交代替換。隨著氧化作用向礦石內(nèi)部的深入,賦存與基質(zhì)和鮞粒中的鮞綠泥石大量風化溶解,Al、Si、Fe、Mg等元素隨之遷移。其中的Fe2+氧化為Fe3+形成針鐵礦及赤鐵礦的集合體,將礦石“染成”紅褐色。在這個過程中,賦存于硬水鋁石中的元素Al沒有明顯遷移,較穩(wěn)定。因此在堆積型鋁土礦中,Al相對富集。鋁土礦中微量元素的遷移隨著礦物的溶解與結(jié)晶進行。在鋁土礦演化過程中,元素Cr與Ti具有較一致的變化規(guī)律。鋁土礦中稀土元素Ce的遷移變化與其它稀土元素的變化存在明顯不一致,說明Ce很可能賦存于稀土礦物氟碳鈣鈰礦當中,其遷移與稀土礦物的風化溶解有關。鋁土礦中LREE的含量高,但在風化的過程中更易遷移,在鋁土礦演化過程中HREE有相對富集的趨勢。
[Abstract]:Guanxi area is an important place of production of bauxite in China. Sanhe bauxite area is located in the southwest of western Guangxi, and the surrounding Debao, Napo bauxite constitutes a very large bauxite field. Guanxi bauxite is a typical karst type, including Permian sedimentary bauxite and Quaternary accumulative bauxite. Among them, accumulative bauxite has high grade, large reserves and is easy to be mined and processed, so it is the main object of development at present. Accumulative bauxite is sedimentary bauxite, which is uplifted, broken, weathered and finally deposited in karst depressions. In this paper, the evolution process of bauxite is studied in detail on the scale of minerals and elements by means of various experimental tests and data statistics. The mineral composition and composition of the ore are analyzed by X-ray diffraction and electron probe. The results show that the main mineral composition of the bauxite is hard boehmite, oolitic chlorite, anatase, pyrite, ilmenite, goethite. Kaolinite, etc The minerals in bauxite are of different shapes, and the mineral composition of bauxite is mixed and symbiotic. Under supergene conditions, the minerals in bauxite are weathered and altered, and most minerals are mixed or replaced by elements, and the mineral composition is mixed. The geochemical composition analysis shows that the main chemical compositions of the Sanhe bauxite are Al _ 2O _ 3H _ 2O _ 2 Fe _ 2O _ 3H _ 2O _ 3 Fe O _ 2O _ 2 O _ 2O _ 2O _ 2O and Al _ 2O _ 3H _ 2O. Other composition content is less than 1%, bauxite maturity is high. The contents of Zr and Cr in trace elements are very high. The average contents were 867.93 脳 10 ~ (-6) and 792.16 脳 10 ~ (-6), respectively. In addition, the contents of Zn and V in the bauxite are also higher, with an average content of 100 脳 10 ~ (-6) ~ 40 脳 10 ~ (-6). The average contents of Th and U of the other elements are in the range of 10 脳 10 ~ (-6) ~ 100 脳 10 ~ (-6). The total amount of rare earth in the ore is large and the light rare earth is enriched as a whole. During the evolution of the primary sedimentary ore, it was first influenced by the leaching of the primary sedimentary ore by the water system, and the ore was still mainly in the reduction environment. At first, some minerals passing through the fissure are weathered and dissolved, some elements are taken away by flowing water, and some elements are replaced by various metasomatism in the ore. Along with the oxidation into the ore interior, a large number of weathered and dissolved elements, such as AlAlSiSiFePg-mg in the matrix and oolitic particles, are transported. The Fe2 is oxidized to Fe3 to form an aggregate of goethite and hematite, and the ore is "dyed" reddish brown. In this process, the element Al in hard boehmite has no obvious migration and is relatively stable. Therefore, Al is relatively enriched in accumulative bauxite. The migration of trace elements in bauxite occurs with the dissolution and crystallization of minerals. During the evolution of bauxite, the variation of Cr and Ti is consistent. The migration change of rare earth element ce in bauxite is obviously inconsistent with that of other rare earth elements, which indicates that ce probably exists in the rare earth mineral, fluorocarbon-calcium cerium ore, and its migration is related to the weathering and dissolution of rare earth minerals. The content of LREE in bauxite is high, but it is easier to migrate during weathering, and HREE is relatively enriched during the evolution of bauxite.
【學位授予單位】：中國地質(zhì)大學(北京)
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：P618.45

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本文編號：1885043