利用川南硫铁尾矿制备莫来石晶须的试验研究
发布时间：2018-11-28 09:28
【摘要】：川南地区硫铁矿储量巨大,为全国五大硫矿生产基地之一,但粗放型的开采方式,生产者环保意识薄弱以及相对落后的生产工艺水平等因素造成大量尾矿堆积。数十年的开采及炼磺所产生的尾矿废渣被大量堆存于山坡、耕地或排入河流,导致大面积耕地损失和河流污染,严重影响了当地人民的生产生活,甚至危及其生命健康。因此,关于川南硫铁尾矿综合开发利用的研究极具现实意义。莫来石晶须是运用于复合材料一种性能优异的增强补韧材料。在一定条件下,高岭土可转化为莫来石,而高岭土正是川南硫铁尾矿的主要矿物组成,这就为硫铁尾矿的综合开发利用提供了一种可能性。本文以川南硫铁尾矿的矿物组成及化学组成分析为基础,验证了以硫铁尾矿为原料采用熔盐法在1000℃以下合成莫来石晶须的可行性,并从煅烧温度、保温时间、升温-冷却方式、尾矿的成分调整、杂质含量、铝源及熔盐介质选择等方面探究了这些因素对制备莫来石晶须的影响,并利用荧光光谱分析(XRF)、等离子体光谱仪(ICP-OES)、 X射线衍射(XRD)、扫描电镜(SEM)等测试方法对制得产物进行表征分析,得出以下结论：(1)川南硫铁尾矿的矿物组成以高岭土为主,主要杂质Fe、Ti分别以硫铁矿、锐钛矿形式富存于尾矿中,除此之外还存在Ca、K、Mg、C、S及有机质等杂质。(2)以川南硫铁尾矿为原料采用熔盐法可在800-1000℃内成功制备出莫来石晶须。煅烧温度过低或保温时间过短均不利于莫来石晶须的生长,煅烧温度过高时则易导致刚玉杂相的生成,而在950℃下煅烧保温2h,可获得平均直径约为45 nm,长度均在500 nm以上,长径比为10～20的纳米级莫来石晶须。因此,煅烧温度950℃,保温时间2h可作为优选方案。此外,急速升温相比于缓慢升温可形成更多莫来石晶核,这有利于获得大长径比的莫来石纳米晶须。(3)成分调整可有效降低川南硫铁尾矿中Fe、Ca、K和Mg等有害杂质元素的含量,但也会降低有效组分A1203的含量。其中,酸洗过程中酸的浓度及其配比均会对原料中的化学组成造成影响。实验表明,经浓度均为25%的硫酸和盐酸按体积比1：1配置的混合酸酸洗处理和650℃煅烧预处理的川南硫铁尾矿的成分组成更有利于制备莫来石晶须。酸洗处理不能明显减少硫铁尾矿中TiO2的含量,但一定含量范围内的Ti02有助于莫来石晶须的生长。原料的反应活性过低也会导致最终产品中形成除莫来石以外的物相。(4)在反应过程中,能否供给具有高反应活性的γ-Al2O3决定了铝源的优劣,以硫铁尾矿为原料制备莫来石晶须的优选铝源为A12(SO4)3,但若进行工业化大规模生产,选用高品质铝矾土的成本相对较低,将其作为优选铝源。(5)熔盐介质熔点的高低及其液相的粘度大小都会对莫来石晶须的合成造成影响。Na2SO4的熔点为884℃,且可与A12(SO4)3发生共融形成液相,该液相在950℃时的粘度系数低,而γ-A1203和Si02在该液相中的过饱和度很小,容易析出莫来石晶须,且晶须长径比大。将K2SO4与Na2SO4质量比1：1混合得到的混合熔盐介质可在一定程度上实现粘度降低,改善晶须形貌,但因K2SO4而产生晶须团聚现象不可避免。因而,Na2S04可作为优选熔盐介质。
[Abstract]:The reserves of the pyrite in the South Sichuan area are huge, which is one of the five major sulfur ore production bases in the whole country, but the mining method of the extensive type, the weak consciousness of the producer and the relative backward production technology level cause a large number of tailings to accumulate. The decades of exploitation and the tailings waste residue produced by the production of the sulfur are piled up on the hillside, cultivated land or discharged into the river, resulting in large-area cultivated land loss and river pollution, seriously affecting the production and life of the local people, and even endangering the life and health of the local people. Therefore, the research on the comprehensive development and utilization of the sulfur-iron tailings in the south of Sichuan is of great practical significance. Mullite whisker is a kind of reinforced and tough material which is used in the composite material. Under certain conditions, the kaolin can be converted into mullite, and the kaolin is the main mineral composition of the sulfur-iron tailings in the south of Sichuan, which provides a possibility for the comprehensive utilization and utilization of the sulfur-iron tailings. Based on the analysis of the mineral composition and chemical composition of the sulfur-iron tailings in the south of Sichuan, the feasibility of synthesizing the mullite whisker by using the molten salt method at the temperature of 1000 DEG C is verified by using the sulfur-iron tailings as the raw material, and the composition of the tailings is adjusted from the sintering temperature, the heat-insulating time, the temperature-increasing-cooling method, the composition of the tailings, The effects of these factors on the preparation of mullite whiskers were investigated in the aspects of impurity content, aluminum source and molten salt medium selection, and fluorescence spectrum analysis (XRF), plasma spectrometer (ICP-OES) and X-ray diffraction (XRD) were used. The product was characterized by scanning electron microscope (SEM) and other test methods. The following conclusions were drawn: (1) The mineral composition of the sulfur-iron tailings in the South Sichuan is mainly kaolin, and the main impurities, Fe and Ti, are rich in the tailings in the form of pyrite and anatase, and there are also Ca, K, and impurities such as Mg, C, S and organic matters. (2) The mullite whisker can be successfully prepared in the range of 800-1000 DEG C by adopting the molten salt method in the process of using the south Sichuan sulfur iron tailings as the raw material. the sintering temperature is too low or the heat preservation time is too short, which is not beneficial to the growth of the mullite crystal whisker; when the sintering temperature is too high, the generation of the corundum hetero phase is easy to be caused; and the average diameter of the corundum impurity phase can be obtained at the temperature of 950 DEG C for 2h, and the average diameter of the corundum heterophase can be obtained, and the length is more than 500 nm. and the aspect ratio is 10 to 20. Therefore, the sintering temperature is 950 DEG C, and the heat-insulating time 2h can be used as a preferable scheme. in addition, that rapid temperature increase can form more mullite crystal nuclei than the slow temperature rise, which is favorable for obtaining the mullite nano-crystal whisker with large aspect ratio. and (3) the component adjustment can effectively reduce the content of the harmful impurity elements such as Fe, Ca, K and Mg in the sulfur iron tailings of the south Sichuan, but also reduce the content of the active component A1 203. The acid concentration and the ratio of the acid in the pickling process can affect the chemical composition of the raw materials. The experiment shows that the composition of the sulfuric acid and hydrochloric acid with a concentration of 25% and hydrochloric acid at a volume ratio of 1: 1 is more beneficial to the preparation of the mullite whisker. The acid-washing treatment can not obviously reduce the content of TiO2 in the sulfur-iron tailings, but Ti02 in a certain amount can help the growth of the mullite whisker. too low the reaction activity of the feedstock also results in the formation of a phase other than mullite in the final product. (4) In the course of the reaction, it is possible to supply the Al-Al2O3 with high reaction activity to determine the advantages and disadvantages of the aluminum source, and the preferred aluminum source for preparing the mullite whisker by using the sulfur iron tailings as the raw material is A12 (SO4) 3, but if the industrial mass production is carried out, the cost of the high-quality bauxite is relatively low, which is used as a preferred source of aluminium. (5) The melting point of the molten salt medium and the viscosity of the liquid phase affect the synthesis of the mullite whisker. The melting point of Na2SO4 is 884.d egree. C. and can be blended with A12 (SO4) 3 to form a liquid phase, the viscosity coefficient of the liquid phase at 950 DEG C is low, and the supersaturation degree of the Al-A1203 and Si02 in the liquid phase is small, the mullite whisker can be precipitated easily, and the aspect ratio of the crystal whisker is large. The mixed molten salt medium obtained by mixing K2SO4 and Na2SO4 with a mass ratio of 1: 1 can reduce the viscosity to a certain extent, and improve the morphology of the crystal whisker, but the phenomenon of whisker agglomeration due to K2SO4 is inevitable. Thus, Na2S04 can be used as a preferred molten salt medium.
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TD926.4
本文编号：2362465
[Abstract]:The reserves of the pyrite in the South Sichuan area are huge, which is one of the five major sulfur ore production bases in the whole country, but the mining method of the extensive type, the weak consciousness of the producer and the relative backward production technology level cause a large number of tailings to accumulate. The decades of exploitation and the tailings waste residue produced by the production of the sulfur are piled up on the hillside, cultivated land or discharged into the river, resulting in large-area cultivated land loss and river pollution, seriously affecting the production and life of the local people, and even endangering the life and health of the local people. Therefore, the research on the comprehensive development and utilization of the sulfur-iron tailings in the south of Sichuan is of great practical significance. Mullite whisker is a kind of reinforced and tough material which is used in the composite material. Under certain conditions, the kaolin can be converted into mullite, and the kaolin is the main mineral composition of the sulfur-iron tailings in the south of Sichuan, which provides a possibility for the comprehensive utilization and utilization of the sulfur-iron tailings. Based on the analysis of the mineral composition and chemical composition of the sulfur-iron tailings in the south of Sichuan, the feasibility of synthesizing the mullite whisker by using the molten salt method at the temperature of 1000 DEG C is verified by using the sulfur-iron tailings as the raw material, and the composition of the tailings is adjusted from the sintering temperature, the heat-insulating time, the temperature-increasing-cooling method, the composition of the tailings, The effects of these factors on the preparation of mullite whiskers were investigated in the aspects of impurity content, aluminum source and molten salt medium selection, and fluorescence spectrum analysis (XRF), plasma spectrometer (ICP-OES) and X-ray diffraction (XRD) were used. The product was characterized by scanning electron microscope (SEM) and other test methods. The following conclusions were drawn: (1) The mineral composition of the sulfur-iron tailings in the South Sichuan is mainly kaolin, and the main impurities, Fe and Ti, are rich in the tailings in the form of pyrite and anatase, and there are also Ca, K, and impurities such as Mg, C, S and organic matters. (2) The mullite whisker can be successfully prepared in the range of 800-1000 DEG C by adopting the molten salt method in the process of using the south Sichuan sulfur iron tailings as the raw material. the sintering temperature is too low or the heat preservation time is too short, which is not beneficial to the growth of the mullite crystal whisker; when the sintering temperature is too high, the generation of the corundum hetero phase is easy to be caused; and the average diameter of the corundum impurity phase can be obtained at the temperature of 950 DEG C for 2h, and the average diameter of the corundum heterophase can be obtained, and the length is more than 500 nm. and the aspect ratio is 10 to 20. Therefore, the sintering temperature is 950 DEG C, and the heat-insulating time 2h can be used as a preferable scheme. in addition, that rapid temperature increase can form more mullite crystal nuclei than the slow temperature rise, which is favorable for obtaining the mullite nano-crystal whisker with large aspect ratio. and (3) the component adjustment can effectively reduce the content of the harmful impurity elements such as Fe, Ca, K and Mg in the sulfur iron tailings of the south Sichuan, but also reduce the content of the active component A1 203. The acid concentration and the ratio of the acid in the pickling process can affect the chemical composition of the raw materials. The experiment shows that the composition of the sulfuric acid and hydrochloric acid with a concentration of 25% and hydrochloric acid at a volume ratio of 1: 1 is more beneficial to the preparation of the mullite whisker. The acid-washing treatment can not obviously reduce the content of TiO2 in the sulfur-iron tailings, but Ti02 in a certain amount can help the growth of the mullite whisker. too low the reaction activity of the feedstock also results in the formation of a phase other than mullite in the final product. (4) In the course of the reaction, it is possible to supply the Al-Al2O3 with high reaction activity to determine the advantages and disadvantages of the aluminum source, and the preferred aluminum source for preparing the mullite whisker by using the sulfur iron tailings as the raw material is A12 (SO4) 3, but if the industrial mass production is carried out, the cost of the high-quality bauxite is relatively low, which is used as a preferred source of aluminium. (5) The melting point of the molten salt medium and the viscosity of the liquid phase affect the synthesis of the mullite whisker. The melting point of Na2SO4 is 884.d egree. C. and can be blended with A12 (SO4) 3 to form a liquid phase, the viscosity coefficient of the liquid phase at 950 DEG C is low, and the supersaturation degree of the Al-A1203 and Si02 in the liquid phase is small, the mullite whisker can be precipitated easily, and the aspect ratio of the crystal whisker is large. The mixed molten salt medium obtained by mixing K2SO4 and Na2SO4 with a mass ratio of 1: 1 can reduce the viscosity to a certain extent, and improve the morphology of the crystal whisker, but the phenomenon of whisker agglomeration due to K2SO4 is inevitable. Thus, Na2S04 can be used as a preferred molten salt medium.
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TD926.4
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