【作者】 于洪浩；

【导师】 薛向欣；

【作者基本信息】 东北大学 ， 冶金资源与生态环境， 2010， 博士

【摘要】 铁尾矿是钢铁行业的固体废弃物,目前我国铁尾矿的堆积量已达2.5×109t以上。铁尾矿既是一种危害,又是一种潜在的二次资源,因此对铁尾矿进行资源化、增值化利用对我国具有重要的战略意义。本文系统探讨了鞍山高硅铁尾矿增值化利用的途径和方式。首先,以铁尾矿为原料,研究了SiO2的常压碱浸出过程,确定了铁尾矿用碱(NaOH)浸出过程中,影响SiO2浸出率的主要因素为：铁尾矿和NaOH与水的固液比,浸出反应温度,浸出反应时间。以此为条件,研究了铁尾矿在碱溶液中浸取SiO2反应的动力学行为。结果表明：固液比1：2,反应温度110℃,反应时间6h,为铁尾矿中SiO2浸出反应的最佳条件。SiO2的常压碱浸出动力学过程可用界面反应模型来描述,其浸出反应动力学方程为1-(3-X)2/3+2(1-X)=k2//t,表观活化能约为14.2 kJ/mol,属于固体内扩散控制。研究了熔盐法分解铁尾矿的实验条件,结果表明：以铁尾矿和NaOH为原料,NaNO3为熔盐,在500℃下煅烧3h使铁尾矿中的惰性SiO2转变成活性的硅酸钠相。以碱浸出的硅酸钠溶液为原料,利用化学沉淀法制备了白炭黑。利用XRD、FT-IR、SEM、TEM和XRF对制取白炭黑的物相结构、粒度形貌和成分含量进行表征。结果表明：白炭黑产品的化学结构为无定型的水合二氧化硅,形貌近似为球状粒子,粒径在150nm以下,白炭黑的比表面积(BET)为108m2/g,SiO2纯度为92.3%,10%悬浮液中pH值为5.5～6.0,加热减量为5.42%,1000℃灼烧减量为6.16%。产品符合中国行业标准HG/T 3061-1999的要求。其次,以十六烷基三甲基溴化铵为模板剂,铁尾矿为硅源采用水热反应法合成出介孔分子筛MCM-41,并研究了晶化工艺(表面活性剂浓度、pH、晶化时间及晶化温度)对合成MCM-41的影响。采用XRD, BET, DTA-TG, HRTEM, SEM, FT-IR对合成的分子筛进行表征。结果表明：在CTAB/SiO2=0.10～0.60,pH=8～11的范围内均能合成出MCM-41分子筛,在CTAB/SiO2=0.15条件下合成MCM-41的有序度较好；随着晶化时间的延长,有利于提高MCM-41的结晶度,促进晶粒生长；升温对水热合成MCM-41晶化过程的促进作用很明显,但晶化温度过高(140℃)或晶化温度过低(25℃),均不能合成出MCM-41。对A3号样品进行结构表征得出：比表面积(BET)为489.3m2/g,有效孔体积(BJH)为1.339cc/g,孔壁厚为0.93nm,具有典型的按六方对称性排列的孔道结构,孔径在2～3nm变化。FT-IR、NMR证明了分子筛具有硅氧四面体骨架。系统研究了A3号分子筛样品对Cu2+、Cr6+、Zn2+三种金属离子及甲基橙的吸附性能,研究了吸附条件(吸附时间、吸附剂投加量、初始浓度、吸附温度)对分子筛吸附性能的影响,并探讨了吸附过程的表观吸附动力学模型及吸附等温模型。结果表明：增加吸附时间、吸附剂投加量、初始浓度、吸附温度都有利于分子筛对Cu2+、Cr6+、Zn2+三种金属离子及甲基橙的吸附。Cu2+、Cr6+、Zn2+三种金属离子及甲基橙的吸附过程都遵循二级表观吸附动力学模型；在吸附剂表面的吸附遵循Langmuir吸附等温线模型。最后,以鞍山铁尾矿为主要原料制备了BaO-Fe2O3-SiO2微晶玻璃,探讨了微晶玻璃组成、主晶相及其结晶动力学等问题,利用正交实验确定了微晶玻璃的适宜热处理制度。结果表明：微晶玻璃的晶化过程中初晶相为BaSi2O5, Ba2FeSi207是中间过渡相并随着温度的升高而消失,最终形成了主晶相BaFe12O19,次晶相为BaSi2O5的微晶玻璃。最佳的热处理工艺为：700℃核化3h,950℃晶化2h。随着热处理温度的升高,微晶玻璃的红外吸收带在800～700cm-1波长范围发生宽化,在1100～900cm-1和500～400cm-1波长范围发生分裂。玻璃结构中的[FeO4]向[FeO6]转化促进了玻璃的析晶,出现了BaFe12O19的红外特征吸收峰。晶体生长指数为2.8,属三维生长。在8.2～12.4GHz范围内的微波介电特性研究表明,介电损耗角正切值达到了0.44,而磁损耗正切值为0.017,具有较好的微波介电特性。更多还原

【Abstract】 Iron ore tailings as a main solid waste in metallurgical industry had 2.5 billion tons in China, which was not only a kind of hazard but a potential secondary resource. Therefore, it has strategic meaning for our country to the complete and value-added utilization of iron ore tailings. In this dissertation, the approach and manner of value-added utilization of Anshan iron ore tailings with high silicon were completely and systemicly studied.Firstly, using iron ore tailings as raw materials, the leaching process of SiO2 were investigated. The main factors, i.e. solid/liquid ratios, reaction temperatures, reaction time, that affect the leaching rate of iron ore tailings in sodium hydroxide were determined, and the digestion kinetics of iron ore tailings in sodium hydroxide was investigated correspondingly. The results showed that the optimum leaching ratio is obtained when the solid/liquid ratio is 1:2 under 110℃for 6h. The leaching kinetics of SiO2 can be represented by the interface reaction model, which was written as the following equation:1—(3—X)2/3+2(1—X)=k2//t. The apparent activation energy calculated for SiO2 leaching is about 14.2 kJ/mol, and the overall leaching rate appears to be controlled by the diffusion in solid. Experiment conditions of decomposition of iron ore tailings with molten salt method were investigated. The results showed that iron ore tailings were mixed with NaOH-NaNO3 and calcined at 500℃for 3 h to yield soluble sodium silicate. The iron ore tailings and NaOH were employed as raw materials, and NaNO3 as salts. The preparation of precipitated silica particle via chemical precipitation using sodium silicate from iron ore tailings and sodium hydroxide as starting materials was successfully demonstrated. The component, morphology and structure of the synthesized particles were characterized by XRD, FT-IR, SEM, TEM and XRF. The chemical structure of precipitated silica was hydrated silicon oxide through FT-IR analysis. The structure of precipitated silica was amorphous by XRD analysis. The SEM and TEM micrograph showed that the shape of precipitated silica particles was nearly spherical, and the average grain diameter was less than 150 nm. The SiO2 purity in the precipitated silica product was 92.3% by X-ray fluorescence analysis. Measured results of chemical and physical properties of precipitated silica as followed:the specific surface area was 114 m2/g, pH in the suspending liquid was 5.5-6.0, and loss on ignition at 1000℃was 6.16%. The product could be comparable with the requirements of HG/T 3061-1999 industrial product standard.Secondly, the mesoporous molecular sieve MCM-41 was synthesized by hydrothermal synthesis method with sodium silicate from iron ore tailings as silica source and hexadecyl trimethyl ammonium bromide (CTAB) as template. The effects of crystallization conditions, i.e. the ratios of CTAB/SiO2, pH values, crystallization time and crystallization temperatures on the formation of MCM-41, were investigated. The synthesized MCM-41 samples were characterized by XRD, BET, DTA-TG, HRTEM, SEM and FT-IR. The mesoporous molecular sieve MCM-41 was formed with CTAB/SiO2 of 0.05-0.6 and pH of 8-11. In the condition of CTAB/SiO2=0.15, the synthesized MCM-41 sample was ordered. The longer the crystallization time, the increase of relative crystallinity of MCM-41. It was favored for the increase of relative crystallinity with prolonging crystallization temperature. The MCM-41 was not formed when the crystallization temperature above 140℃or the crystallization temperature below 25℃. The A3 sample had surface area of 527 m2/g, BJH pore volume of 1.339 cc/g and pore wall thickness of 0.93nm. The pore structure of MCM-41 was well-ordered and symmetrical hexagonal structure, which pore diameter of MCM-41 was changed between 2nm to 3nm. Silicon-oxygen tetrahedron skeletons were confirmed by FT-IR、NMR.The effects of adsorption conditions on the adorption efficiency for Cu2+、Cr6+、Zn2+ and methyl orange (MO) by the MCM-41 absorbents were systemically stuied. The adsorption isothern model and adsorption kinetics medel were also explored.With these parameters increasing, such as the adsorbent time, adsorbent dose, initial concentration and adsorbent temperature, the efficiencies of the Cu2+、Cr6+、Zn2+ and MO were also increased.The adsorption kinetics of MCM-41 absorbents for the Cu2+、Cr6+、Zn2+ and MO were all corresponded to the modified pseudo-second-order equations, and the absorption isotherms was all satisfied to the Langmuir models.Finally, BaO-Fe2O3-SiO2 system glass-ceramics were synthesized from iron ore tailing of Anshan as starting material. Compositions of glass-ceramics, selection of main crystallization and crystallization kinetics were discussed. Utilizing the orthogonal experiment, the optimal formula and heat treatment schedule of foam glass- ceramics were decided. The initial crystalline phase of the sample was BaSi2O5 and Ba2FeSi2O7 as transition crystalline phase changed into BaFe12O19 with increasing of temperature. The final crystalline phases of the glass-ceramics were BaFe12O19 and BaSi2O5. With increasing of crystallization temperature, infrared absorption bands of the sample broaden within the range of 800-700cm-land were splitted within the range of 1100-900cm-1 and 500-400cm-1. It was suggested that the crystallization was accelerated by [FeO4] fundamental unit shifted to [FeO6] in the glass structure and BaFe12O19 as the final crystalline phase was observed. The index of crystal growth is 2.8 and it implies that crystals grow along three dimensional space. The complex dielectric constant and complex permeability dispersion were investigated in 8.2 GHz to 12.4GHz. The results show that maximum dielectric loss is 0.44, but magnetic loss is only 0.017. These new features make the composites be a kind of promising microwave absorber.更多还原