高浓度氯化物废水制备复合硫酸盐及其对离子型稀土的浸取

发布时间：2018-03-25 12:41

本文选题：稀土分离　切入点：氯化物废水　出处：《南昌大学》2015年硕士论文

【摘要】：稀土萃取分离过程可简单看成是消耗酸碱并产生大量盐的过程,也是稀土分离厂污染物的主要来源。因此,如何回收利用氯化物废水是稀土企业减排的主要任务。本文针对高浓度氯化铵(钠)废水的综合利用要求,开展了硫酸与氯化物反应制取盐酸和复合硫酸盐的小试和工业化试验研究,并对复合硫酸盐在离子吸附型稀土的浸取性能进行了评价。具体成果有:分别研究了硫酸与氯化钠和氯化铵废水反应制取盐酸和复合硫酸盐的工艺条件(加酸比、温度、时间和压力)对产酸浓度、氯化物转化率和复合硫酸盐组成的影响。结果表明:随着加酸比n(H+):n(Cl-)的提高,氯化物的转化率提高,而在加酸比固定的条件下,随氯化物盐浓度的提高,蒸出盐酸的浓度增大,但其盐酸蒸出摩尔数与加入氢离子摩尔数的比值基本不变,而且在减压条件下,可以使盐酸蒸出率比常压高出7%左右;当氯化物浓度在4mol/L以上时,蒸出盐酸的浓度均比盐浓度高。可直接用作稀土萃取分离中的洗酸和反酸。蒸出盐酸后的复合硫酸盐组成与加酸比直接相关,当加酸比高于1.8时,主要产物为硫酸氢铵(钠);加酸比为1.6左右时主要为硫酸氢三铵;加酸比低于1.4时,还有未转化完全的氯化物。所得复合硫酸盐均可用于离子吸附型稀土的浸出,而且可以替代硫酸用作稀土碳铵沉淀母液回收使用时的pH调节剂和铵离子补充剂。与此同时,还研究了使用酸性硫酸铵或硫酸铝溶液对离子吸附型稀土的浸取,以提高难浸稀土的浸出,并使浸出的铝杂质能用于循环浸矿并稳定在尾矿中。其方法是利用复合硫酸盐来溶解矿山预处理渣,使稀土和大部分铝溶解进入溶液,用萃取法回收稀土后的萃余液返回用于离子吸附型稀土的第二阶段浸取,使难浸稀土和尾矿中的铵进入溶液而得到进一步的回收利用,再用石灰水护尾,使大部分铝保存在尾矿中。
[Abstract]:The process of rare earth extraction and separation can be regarded as the process of consuming acid and alkali and producing a large amount of salt, and is also the main source of pollutants in rare earth separation plant. How to recover and utilize chloride wastewater is the main task of rare earth enterprises to reduce emissions. This paper aims at the comprehensive utilization requirements of high concentration ammonium chloride (sodium chloride) wastewater. Pilot and industrial studies on the preparation of hydrochloric acid and complex sulfate by reaction of sulfuric acid with chloride were carried out, The leaching performance of complex sulfate in ion adsorbed rare earths was evaluated. The specific results are as follows: the technological conditions of the reaction of sulfuric acid with sodium chloride and ammonium chloride wastewater to produce hydrochloric acid and compound sulfate (acid addition ratio, temperature, etc.). The effect of time and pressure on the concentration of acid production, the conversion rate of chloride and the composition of compound sulfate. The results showed that the conversion of chloride increased with the increase of acid addition ratio, and the conversion rate of chloride increased when the acid ratio was fixed. With the increase of chloride concentration, the concentration of hydrochloric acid increased, but the ratio of the number of hydrochloric acid vaporized to the molar number of hydrogen ion was almost unchanged, and under the condition of decompression, the evaporation rate of hydrochloric acid was about 7% higher than that of normal pressure. When the concentration of chloride is above 4mol/L, the concentration of HCl is higher than that of salt. It can be directly used as washing acid and regurgitating acid in the extraction separation of rare earth. The composition of compound sulfate after distilling out of HCl is directly related to the ratio of adding acid to acid, and the ratio of adding acid to acid is higher than 1.8. The main products are ammonium hydrogen sulfate (Na ~ (2 +)) (Na ~ (2 +)); when the ratio of acid to acid is about 1.6 or so, there is also an incomplete chloride when the ratio of acid to acid is less than 1.4. The resulting compound sulfate can be used in the leaching of ion-adsorbed rare earths. It can be used as pH regulator and ammonium ion supplement in the recovery of ammonium carbonate precipitation mother liquor. At the same time, the leaching of ion adsorbed rare earths by acid ammonium sulfate or aluminum sulfate solution has been studied. In order to improve the leaching of refractory rare earths, and to make the leached aluminum impurities can be used in circulating leaching and stabilizing in tailings, the method is to dissolve the pretreatment slag of mine by using compound sulfate, so that the rare earth and most of aluminum can be dissolved into the solution. The residual solution of rare earths recovered by extraction is returned to the second stage of leaching of ion-adsorbed rare earths, so that the ammonium in refractory rare earths and tailings can be further recovered and used to protect the tail with lime-water. Keep most of the aluminum in tailings.
【学位授予单位】：南昌大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X756

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