【作者】 洪伟；

【导师】 段昕辉；

【作者基本信息】 河北工业大学 ， 工程硕士（专业学位）， 2021， 硕士

【摘要】 选矿厂提取铁矿石中有用的组分后会排放大量的铁尾矿,这些铁尾矿不仅占据大面积土地,而且对周围的环境造成了不可忽视的负面影响。铁尾矿中含有丰富的硅元素和少量铝、铁元素,是潜在的二次资源。本文以铁尾矿为原料,采用溶胶凝胶工艺和常压干燥工艺制备二氧化硅气凝胶,研究了溶胶凝胶和常压干燥流程中的工艺参数变化对二氧化硅气凝胶比表面积的影响,并结合对亚甲基蓝和孔雀石绿的吸附实验,考察了二氧化硅气凝胶的吸附性能。主要工作内容如下:通过分析铁尾矿高温碱熔处理前后的物相变化,确定了高温碱熔处理可以使铁尾中硅、铝、铁的氧化物或硅酸盐转化为可溶的硅酸钠、硅铝酸钠和亚铁酸钠。上述产物经过水洗和静置分离后可以分别获得含铝、铁元素的硅源,再经过溶胶凝胶、老化和常压干燥工艺可以得到含有铝、铁组分的二氧化硅气凝胶。在获得硅源的基础上,考察了催化剂浓度、催化剂种类、老化时间和干燥温度对二氧化硅气凝胶比表面积的影响。在优化实验中,磷酸催化得到的二氧化硅气凝胶的比表面积比硫酸和柠檬酸催化得到的二氧化硅气凝胶高,在磷酸溶液的体积分数15%至25%、老化时间12 h至72 h、干燥温度50°C至75°C的条件范围内,二氧化硅气凝胶的比表面积均呈现先增大后减小的趋势。在磷酸溶液体积分数为20%、老化时间为48 h、干燥温度为55°C的条件下,分别制得了比表面积为922.03 m²/g和683.84m²/g的二氧化硅气凝胶。X射线衍射（XRD）、扫描电子显微镜（SEM）和傅里叶红外光谱（FTIR）等分析表明,两种二氧化硅气凝胶均为无定型态的多孔结构,高比表面积的二氧化硅气凝胶中含有4.41 wt%的Al₂O₃,低比表面积的二氧化硅气凝胶含有8.25 wt%的Al₂O₃和3.47 wt%的Fe₂O₃,铝、铁参与了二氧化硅网络骨架的形成。以亚甲基蓝和孔雀石绿为目标污染物,研究了两种二氧化硅气凝胶的吸附性能。含有Al₂O₃的二氧化硅气凝胶对亚甲基蓝和孔雀石绿的最大吸附量分别为318.47 mg/g和434.78 mg/g,并且对亚甲基蓝的吸附主要是物理吸附,对孔雀石绿的吸附包含物理吸附和化学吸附。含有Al₂O₃和Fe₂O₃的二氧化硅气凝胶对亚甲基蓝和孔雀石绿的最大吸附量分别为334.44 mg/g和454.54 mg/g,并且对亚甲基蓝和孔雀石绿的吸附包含物理吸附和化学吸附。更多还原

【Abstract】 After extracting useful components in iron ore,the concentrator will discharge a large amount of iron tailings,these iron tailings not only occupy a large area of land,but also cause a non-negligible negative impact on the surrounding environment.Iron tailings contain abundant silicon and a small amount of aluminum and iron,which are potential secondary resources.In this paper,iron tailings was used as raw materials to prepare silica aerogel by sol-gel process and atmospheric drying process.The effect of the process parameter changes in the sol-gel and atmospheric drying process on the specific surface area of silica aerogel was studied,and combined with the adsorption experiment on methylene blue and malachite green,the adsorption performance of silica aerogel was investigated.The main work content is as follows:By analyzing the phase changes before and after the high-temperature alkali fusion treatment of iron tailings,it is determined that the high-temperature alkali fusion treatment can convert the oxides or silicates of silicon,aluminum,and iron in the iron tailings into soluble sodium silicate,sodium aluminosilicate and sodium ferrous.The above products can be washed with water and separated by standing to obtain a silicon source containing aluminum and iron,and then subjected to sol-gel,aging and atmospheric drying processes to obtain silica aerogels containing aluminum and iron components,respectively.On the basis of obtaining silicon sources,the effects of catalyst concentration,catalyst type,aging time and drying temperature on the specific surface area of silica aerogel were investigated.In the optimization experiment,the specific surface area of the silica aerogel catalyzed by phosphoric acid is higher than that of the silica aerogel catalyzed by sulfuric acid and citric acid,within the conditions of that volume fraction of phosphoric acid solution from 15%to 25%,aging time from 12 h to 72 h,drying temperature from 50°C to 75°C,the specific surface area of silica aerogels increases first and then decreases.Under the conditions of a phosphoric acid solution volume fraction of 20%,an aging time of 48 h,and a drying temperature of 55°C,silica aerogel with specific surface areas of 922.03 m²/g and 683.84m²/g were prepared.The results of X ray diffraction（XRD）,scanning electron microscopy（SEM）and fourier transform infrared spectroscopy（FTIR）showed that two kinds of silica aerogels were amorphous porous structure,the silica aerogel with high surface area contained4.41 wt%Al₂O₃,and the silica aerogel with low surface area contained 8.25 wt%Al₂O₃ and3.47 wt%Fe₂O₃,aluminum and iron was involved in the formation of silica network framework.With methylene blue and malachite green as target pollutants,the adsorption properties of two silica aerogels were studied.The maximum adsorption capacity of silica aerogel containing Al₂O₃ for methylene blue and malachite green are 318.47 mg/g and 434.78 mg/g,respectively,and the adsorption to methylene blue is mainly physical adsorption,the adsorption to malachite green includes physical adsorption and chemical adsorption.The maximum adsorption capacity of silica aerogel containing Al₂O₃ and Fe₂O₃ for methylene blue and malachite green are 334.44 mg/g and 454.54 mg/g,respectively,and the adsorption to methylene blue and malachite green includes physical adsorption and chemical adsorption.更多还原