纯物质模拟煤矸石酸溶物水解分离基础研究

发布时间：2019-05-30 00:25

【摘要】：煤矸石是煤炭采掘、洗选过程中产生的固体废物,其大量堆存会带来严重的环境污染和资源浪费。根据煤矸石的化学组成,开发环境友好型技术工艺,提高煤矸石资源化综合利用具有重要意义。为解决课题组在煤矸石多金属提取中试研究中出现的产物粒度细、过滤性差、洗涤困难、滤饼含水量高等问题,本论文以十八水硫酸铝[Al2(SO4)3 · 18H20]为沉淀前驱剂,以碳酸钠[Na2C03]作沉淀剂水解制备氢氧化铝,探讨pH、温度、浓度、晶种等因素对硫酸铝水解产物过滤性、物相和形貌的影响,采用X射线衍射(XRD)、傅里叶变换红外光谱(FT-IR)、热重分析(TGA)和扫描电子显微镜(SEM)等方法综合分析其水解机理,为煤矸石酸溶物水解机制提供一定理论依据。并考察晶种对模拟体系和煤矸石酸溶物真实体系水解产物过滤性的影响。本论文得到以下结论:(1)pH3时,硫酸铝溶液中Al3+以[Al(OH2)6]3+的形式存在,pH升高时[Al(OH2)6]3+水解生成[Al(OH)4(OH2)2]-,[Al(OH)4(OH2)2]-在 Na+水化作用下脱水缩合成[A12(OH)8(OH2)2]2-,碱性增强使[Al2(OH)8(OH2)2]2-转化为[A120(OH)6]2-,最终形成氢氧化铝沉淀。(2)75℃下,pH=3、5、7时,Al2(SO4)3水解产物为无规则团聚的非晶态氢氧化铝;pH=9、11时,氢氧化铝从非晶态转变为晶态的γ-AlOOH及少量α-Al(OH)3,pH越大产物过滤性越好。(3)pH=4.5时,反应温度T≤96℃时,A12(S04)3水解产物为无规则团聚的非晶态氢氧化铝,产物孔径分布不均匀;水解产物进行水热处理,T=120℃时,非晶态氢氧化铝向NaAl3(S04)2(OH)6转变;T=150、180℃时,A12(S04)3水解产物为斜方六面体NaAl3(804)2(OH)6,择优向(113)面生长,且产物孔径分布均匀。(4)中空海胆状勃姆石[γ-AlOOH]、实心球形氢氧化铝、立方状三水铝石[Al(OH)3]作晶种能提高Al3+、Fe2+、Ti4+水解体系水解产物的过滤性,改善水解产物的物相和形貌。(5)pH=4.5、反应温度T=75℃时,立方状三水铝石[Al(OH)3]作晶种加入煤矸石酸溶物中能提高水解产物的过滤性,水解产物呈块状且具有一定晶型。
[Abstract]:Coal gangue is a kind of solid waste produced in the process of coal mining and washing. A large number of coal gangue will bring serious environmental pollution and waste of resources. According to the chemical composition of coal gangue, it is of great significance to develop environmentally friendly technology and improve the comprehensive utilization of coal gangue resources. In order to solve the problems of fine particle size, poor filtration, difficult washing and high water content of filter cake, Al2 (SO4) 3 18H20 was used as precipitation precursor in order to solve the problems of fine particle size, poor filtration, difficult washing and high water content of filter cake. Aluminum hydroxide was prepared by hydrolysis of sodium carbonate [Na2C03] as precipitator. The effects of pH, temperature, concentration and seed on the filtration, phase and morphology of aluminum sulfate hydrolysate were discussed. X-ray diffraction (XRD), was used. Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA) and scanning electron microscope (SEM) were used to analyze the hydrolysis mechanism of coal gangue, which provided a theoretical basis for the hydrolysis mechanism of acid solution of coal gangue. The effect of seed on the filtration of hydrolysate in simulated system and real system of coal gangue acid solution was also investigated. In this paper, the following conclusions are obtained: (1) at pH3, Al3 in aluminum sulfate solution exists in the form of [Al (OH2) 6] 3, and when pH increases, [Al (OH2) 6] 3 is hydrolyzed to form [Al (OH) 4 (OH2) 2] -. [Al (OH) 4 (OH2) 2]-dehydrated and condensed to [A12 (OH) 8 (OH2) 2] 2 under the hydration of Na, and the alkaline enhancement transformed [Al2 (OH) 8 (OH2) 2] 2-into [A120 (OH) 6] 2, Finally, aluminum hydroxide precipitation was formed. (2) at 75 鈩，

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