發(fā)布時(shí)間：2018-06-04 22:06

  本文選題：高砷污酸 + 石灰石預(yù)中和��； 參考：《昆明理工大學(xué)》2017年碩士論文

【摘要】：有色金屬冶煉含砷廢水的除砷固砷是冶金行業(yè)目前所面臨的重要課題,臭蔥石沉淀法是處理高砷廢水幾種常用方法之一。本文以含砷污酸為研究對(duì)象進(jìn)行除砷研究。研究內(nèi)容主要分為兩個(gè)部分:首先通過向高砷污酸中投入石灰石作為降低污酸酸度的廉價(jià)原料,同時(shí)保證得到的石膏含有一個(gè)很低標(biāo)準(zhǔn)的砷含量,符合回收利用標(biāo)準(zhǔn)的實(shí)驗(yàn)研究。然后將剩余含有大量砷的溶液用鐵鹽合成穩(wěn)定臭蔥石的方法,高效穩(wěn)定的去除溶液中的砷并且能夠達(dá)到國家長期堆存處理的標(biāo)準(zhǔn),在處置高砷溶液過程中,將砷鐵溶液逐步混合形成臭蔥石沉淀,含砷溶液初始pH值、反應(yīng)溫度、反應(yīng)時(shí)間以及不同砷鐵比等因素對(duì)臭蔥石晶體形成的影響,并對(duì)各個(gè)因素實(shí)驗(yàn)所得沉淀物進(jìn)行了各項(xiàng)分析、浸出毒性分析和剩余溶液中As和Fe的含量變化。得出以下結(jié)論:(1)在第一步石灰石預(yù)中和實(shí)驗(yàn)過程中,石灰石添加量對(duì)產(chǎn)生石膏含砷穩(wěn)定性影響很大,通過實(shí)驗(yàn)研究發(fā)現(xiàn):當(dāng)pH高于0.5后得到的石膏毒性浸出液含砷量高于國家標(biāo)準(zhǔn),在不同溫度對(duì)產(chǎn)生石膏影響研究結(jié)果發(fā)現(xiàn):溫度升高對(duì)形成石膏影響只有略微效果,為了本方法能利用到工程實(shí)際操作中降低成本,選擇室溫下進(jìn)行中和污酸。因此在室溫條件下,控制終點(diǎn)pH值為0.5為最佳條件。(2)在第二步鐵鹽沉砷形成臭蔥石反應(yīng)過程中研究發(fā)現(xiàn):改善含砷溶液的初始pH值,能獲得較高的As去除率,當(dāng)pH=2時(shí)的濾液含砷量、沉砷率和SEM圖表明此時(shí)的結(jié)果優(yōu)于pH的其他值,故選擇pH=2為最佳條件。提高反應(yīng)過程的溫度會(huì)有利于臭蔥石晶體的形成與生長,本研究最終認(rèn)為最佳選擇的溫度90℃。增加反應(yīng)時(shí)間會(huì)有利于臭蔥石晶體的形成與長大。為了提高As沉淀率并且得到結(jié)晶程度好的含砷物質(zhì),本研究認(rèn)為最佳選擇反應(yīng)時(shí)間為12 h。略微過量的硫酸鐵能促進(jìn)反應(yīng)過程中臭蔥石晶體的形成與生長,本研究方法不宜添加太多的鐵鹽成分,因此鐵砷摩爾比為1.5是一個(gè)較好的參數(shù)選擇。最終通過實(shí)驗(yàn)結(jié)果得出在pH=2,反應(yīng)溫度在90℃,Fe/As=1.5條件下反應(yīng)12 h可以得到毒性浸出低于5 mg/L的標(biāo)準(zhǔn)的臭蔥石晶體。
[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，

本文編號(hào)：1978997