氯化亚铁废酸液回收利用工艺研究

发布时间：2019-01-12 07:57

【摘要】：随着国家电网、通信网络等行业的迅猛发展,对铁塔的需求日益剧增,铁塔构件进行防腐处理前,常采用稀盐酸清洗以去除其表面的疏松氧化层。该酸洗废水Fe2+、Zn2+含量高,pH值低,有较强腐蚀性,目前尚未有经济合理的处理方案。因此,回收利用酸洗废液生产高附加值产品越来越受到人们的重视。针对某铁塔钢构厂的氯化亚铁废酸液,在分析了其基本成分和性质的基础上,开发了一种氯化亚铁废酸液回收利用的新工艺,该工艺主要包括降温结晶法回收废酸液制备氯化亚铁、氯化亚铁制备氧化铁黄晶种、铁黄晶种的生长三个步骤。该工艺流程具有能量消耗低、生产周期短、产量大、废液资源化利用率高等优点,成功将废酸液“变废为宝”。本文主要研究内容如下：(1)加热浓缩-降温结晶法回收制备氯化亚铁,通过Aspen Plus软件模拟和优化,采用四效蒸发-降温结晶法制备氯化亚铁晶体,设置第一效蒸发器压力5atm、汽化分率0.09；第二效蒸发器压力3 atm、温度143.65℃；第三效蒸发器压力1 atm、温度113.95℃；第四效蒸发器压力0.2 atm、温度76.45℃；并通过结晶器降温至25℃结晶,得到氯化亚铁晶体。根据模拟结果,每蒸出lkg水,四效蒸发比直接加热浓缩-降温结晶法节约能量67.4%,大大提高了降温结晶法回收废酸液的能量利用效率。(2)设计并制作了一种氧化铁黄颜料制备的气液固三相反应器,并利用该反应器开展了氧化铁黄晶种制备、晶种生长的实验研究。首先,考察了温度、压力、初始Fe(OH)2浓度对铁黄晶种生成速率的影响,得到了铁黄晶种生成速率的关系式。结果表明,常温下,在三相反应器内,增加空气流量、液相流量、原料液浓度及反应压力,降低Fe(OH)2胶体颗粒粒径,均有利于氧化铁黄晶种的生成。气液固三相反应器中,晶种制备的最佳工艺条件为：气相流量V=700 L/h、液相流量L=70 L/h、初始pH=7.5、Fe(OH)2胶体颗粒700 nm、初始Fe(OH)2浓度C=0.2～0.6mol/L、反应器压力P=0.1～0.5MPa、反应温度20～30℃。其次,将制得的晶种送入三相反应器内实现晶种的长大,控制反应温度120℃,反应压力3atm,反应15-25min后,经过滤、洗涤、干燥等处理后得到氧化铁黄样品,并通过SEM、 XRD等技术对样品进行了分析和评价,所得氧化铁黄颜料达到了我国化工行业一级标准。(3)设计并组装了氧化铁黄连续化生产的实验装置,考察了Fe(OH)2初始浓度和进料流量对氧化铁黄制备的影响,获得了三塔串联氧化铁黄制备的最佳工艺条件：氢氧化亚铁进料流量20 L/h、进料浓度0.3 mol/L、循环槽操作循环比3-5、晶种制备阶段填料塔温度25℃,压力1 atm、晶种生长阶段温度120℃,压力4 atm。
[Abstract]:With the rapid development of national power grid, communication network and other industries, the demand for iron tower is increasing day by day. Before anticorrosion treatment of tower components, dilute hydrochloric acid is often used to clean the loose oxidation layer on its surface. The acid pickling wastewater has high Fe2, high Zn2 content, low pH value and strong corrosiveness, so there is no economical and reasonable treatment scheme at present. Therefore, people pay more and more attention to the recovery and utilization of acid pickling waste liquid to produce high added value products. Based on the analysis of the basic composition and properties of ferrous chlorinated waste acid liquid in a steel tower steel construction plant, a new process for recovering and utilizing ferrous chlorinated waste acid liquid was developed. The process includes three steps: recovery of waste acid solution to produce ferrous chloride, preparation of iron oxide yellow seed and growth of iron yellow crystal by cooling crystallization method. The process has the advantages of low energy consumption, short production cycle, large output and high utilization ratio of waste liquid. The main contents of this paper are as follows: (1) Ferrous chloride crystals were prepared by four-way evaporation-cooling crystallization method through Aspen Plus software simulation and optimization. First effect evaporator pressure 5 atm, vaporization rate 0.09; Second effect evaporator pressure 3 atm, temperature 143.65 鈩，

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