含砷污酸中和—臭葱石沉砷稳定化研究

发布时间：2018-06-04 22:06

  本文选题：高砷污酸 + 石灰石预中和　； 参考：《昆明理工大学》2017年硕士论文

【摘要】：有色金属冶炼含砷废水的除砷固砷是冶金行业目前所面临的重要课题,臭葱石沉淀法是处理高砷废水几种常用方法之一。本文以含砷污酸为研究对象进行除砷研究。研究内容主要分为两个部分:首先通过向高砷污酸中投入石灰石作为降低污酸酸度的廉价原料,同时保证得到的石膏含有一个很低标准的砷含量,符合回收利用标准的实验研究。然后将剩余含有大量砷的溶液用铁盐合成稳定臭葱石的方法,高效稳定的去除溶液中的砷并且能够达到国家长期堆存处理的标准,在处置高砷溶液过程中,将砷铁溶液逐步混合形成臭葱石沉淀,含砷溶液初始pH值、反应温度、反应时间以及不同砷铁比等因素对臭葱石晶体形成的影响,并对各个因素实验所得沉淀物进行了各项分析、浸出毒性分析和剩余溶液中As和Fe的含量变化。得出以下结论:(1)在第一步石灰石预中和实验过程中,石灰石添加量对产生石膏含砷稳定性影响很大,通过实验研究发现:当pH高于0.5后得到的石膏毒性浸出液含砷量高于国家标准,在不同温度对产生石膏影响研究结果发现:温度升高对形成石膏影响只有略微效果,为了本方法能利用到工程实际操作中降低成本,选择室温下进行中和污酸。因此在室温条件下,控制终点pH值为0.5为最佳条件。(2)在第二步铁盐沉砷形成臭葱石反应过程中研究发现:改善含砷溶液的初始pH值,能获得较高的As去除率,当pH=2时的滤液含砷量、沉砷率和SEM图表明此时的结果优于pH的其他值,故选择pH=2为最佳条件。提高反应过程的温度会有利于臭葱石晶体的形成与生长,本研究最终认为最佳选择的温度90℃。增加反应时间会有利于臭葱石晶体的形成与长大。为了提高As沉淀率并且得到结晶程度好的含砷物质,本研究认为最佳选择反应时间为12 h。略微过量的硫酸铁能促进反应过程中臭葱石晶体的形成与生长,本研究方法不宜添加太多的铁盐成分,因此铁砷摩尔比为1.5是一个较好的参数选择。最终通过实验结果得出在pH=2,反应温度在90℃,Fe/As=1.5条件下反应12 h可以得到毒性浸出低于5 mg/L的标准的臭葱石晶体。
[Abstract]:Removing arsenic and fixing arsenic from wastewater containing arsenic from non-ferrous metal smelting is an important subject facing the metallurgical industry at present. In this paper, arsenic removal from arsenic-contaminated acid was studied. The content of the study is divided into two parts: firstly, limestone is used as a cheap raw material to reduce the acidity of polluted acid, and the gypsum has a very low arsenic content. Experimental study meeting the standard of recycling. Then the solution containing a large amount of arsenic is synthesized with iron salt to stabilize the stinking onion, and the arsenic in the solution can be removed efficiently and stably and can meet the national standard of long-term storage treatment. In the process of disposal of high-arsenic solution, The effects of the initial pH value of arsenic solution, reaction temperature, reaction time and different ratio of arsenic to iron on the crystal formation were studied. The contents of as and Fe in the residual solution were determined by the analysis of the leaching toxicity and the contents of as and Fe in the residual solution. The following conclusion is drawn: (1) during the first step of the limestone pre-neutralization experiment, the amount of limestone added has a great influence on the stability of the gypsum containing arsenic. The experimental results show that the arsenic content of the gypsum toxic leachate obtained when pH is higher than 0.5 is higher than that of the national standard, and the effect of different temperature on gypsum production is found to be only slightly affected by the increase of temperature. In order to reduce the cost in engineering practice, the neutralized acid is selected at room temperature. Therefore, at room temperature, the best condition is to control the terminal pH value of 0.5.) in the second step, it is found that the removal rate of as can be higher by improving the initial pH value of arsenic-containing solution. When pH = 2, the amount of arsenic in the filtrate, arsenic precipitation rate and SEM diagram show that the result is superior to other pH values, so pH=2 is the best condition. Increasing the temperature of the reaction process will be beneficial to the formation and growth of the crystal. The optimum temperature is 90 鈩，

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