【摘要】：目前,對(duì)于石煤酸浸液常采用二(2-乙基己基)膦酸酯(P204)萃取,而該工藝一般需用石灰調(diào)整酸浸液pH值為2,萃取前需對(duì)酸浸液進(jìn)行還原處理,萃取后再對(duì)反萃液進(jìn)行氧化。流程復(fù)雜,藥劑成本較高,且在調(diào)節(jié)pH時(shí)固液分離也較為困難。同時(shí),由于P204為陽離子萃取劑,所以對(duì)于酸浸液中大量存在的鐵、鋁、鎂等雜質(zhì)分離效果一般,較難分離完全。為了縮短工藝流程,降低成本,本文提出了在較低的pH值下采用叔胺類萃取劑N235(三烷基胺)萃取石煤酸浸液,水洗后再反萃回收釩。試驗(yàn)研究了N235對(duì)酸浸液中主要離子的萃取性能。結(jié)果表明,在同等條件下,N235萃取V(V)的萃取率顯著高于V(Ⅳ)。升高溶液pH有利于V(V)的萃取,在pH為1時(shí)V(V)的單級(jí)萃取率可達(dá)97.21%。在pH=0~2時(shí),N235對(duì)Fe2+、Al3+、Mg2+、PO43-、Si2O32-的萃取能力均較弱,而控制體系pH值小于1.5,可以顯著降低N235對(duì)Fe3+的萃取。整體上Fe3+、Al3+、Mg2+、PO43-、Si2O32-的共萃程度較弱,對(duì)釩萃取影響較小。研究確定了N235萃取石煤酸浸液的工藝參數(shù)。在25℃下,有機(jī)相為40%N235、60%煤油,萃取相比O/A為1:4,萃取6分鐘,經(jīng)過2級(jí)萃取,釩的萃取率達(dá)97.82%;洗滌條件為55℃水洗,洗滌相比O/A為1:1,洗滌10分鐘,兩級(jí)硫酸洗脫率為52.5%;反萃劑采用0.8 mol/L碳酸鈉溶液,反萃過程中,反萃相比O/A為3:1,反萃6分鐘,經(jīng)2級(jí)反萃,釩的總反萃率大于99%。而且大部分雜質(zhì)離子被分離,其中鐵、鋁、鈣、鎂等主要雜質(zhì)離子的去除率均高于95%。對(duì)于反萃后有機(jī)相作紅外光譜分析可知,其與萃取前有機(jī)相紅外圖譜特征峰幾乎一致,說明N235萃取劑經(jīng)過反萃后可以循環(huán)利用。采用飽和容量法以及斜率法研究了N235萃取釩的機(jī)理,確定N235萃取釩的萃合物為[R3NH]4[H2V10O28]。通過試驗(yàn),擬合數(shù)據(jù)后得到N235萃取釩的反應(yīng)平衡常數(shù)K為195.434 mol-1·L·s-1,且此時(shí),萃取反應(yīng)焓變H=-10.683 kJ/mol,自由能變G=-13.076 kJ/mol,熵變S=8.032 J/(mol·K)。說明N235萃取釩的反應(yīng)為放熱反應(yīng),萃取溫度的升高不利于N235萃取釩。自由能變G為負(fù)值,說明反應(yīng)可以自發(fā)進(jìn)行,反應(yīng)較易發(fā)生。
[Abstract]:At present, bis (2-ethylhexyl) phosphonic acid ester (P204) is often used to extract the acid leachate of stone coal, but this process usually requires lime to adjust the pH value of the acid leaching solution to 2, and the acid leaching solution should be reduced before extraction. After extraction, the stripping solution is oxidized. The process is complex, the medicament cost is high, and the solid-liquid separation is difficult to adjust pH. At the same time, because P204 is a cationic extractant, it is difficult to separate the impurity such as iron, aluminum, magnesium and so on. In order to shorten the technological process and reduce the cost, the tertiary amine extractant N235 (trialkylamine) was used to extract the bituminous coal acid leachate at low pH value. The extraction properties of main ions in acid leaching solution by N235 were studied. The results showed that the extraction rate of V (V) by N235 was significantly higher than that of V (鈪，

本文編號(hào)：2361696