稀土分离过程氨氮内循环工艺研究

发布时间：2018-01-30 07:16

  本文关键词： 稀土 萃取 氨氮废水 氯化铵分解 硫酸镁　出处：《江西理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：本文针对稀土萃取分离过程氨氮废水治理的难题,结合课题组前期关于离子型稀土矿无氨浸矿的研究成果,设计出稀土分离过程中氨氮内循环浓缩—碱解造氨—硫酸酸化制盐酸治废增效的工艺路线,并对创新工艺各主要环节进行了较为系统的研究。实验发现,常温下氯化铵在稀土溶液中的溶解度随稀土离子浓度的增大而减小,随稀土元素原子序数增大而减小;氯化铵浓度达到饱和状态下,溶液的运动粘度值随原子序数的增大而增大;氯化铵的浓度不影响稀土萃取时油/水分相,即使在氯化铵饱和状态下,萃取过程仍未发生乳化和分相困难等问题。萃取实验表明,氯化铵饱和状态下稀土的萃取容量和萃取分离系数与常规工艺相比,结果相近,轻稀土的萃取容量比重稀土小;轻稀土的分离系数随料液酸度的减小而增大,重稀土恰好相反;另外,反萃酸中含饱和氯化铵对反萃过程无影响,轻稀土的二级反萃率达到98%以上,重稀土达到80%左右。碱解实验表明,氢氧化镁比较适合做氯化铵的分解介质,碱解反应须在沸腾(103℃左右)下进行,最优条件为温度130℃,氢氧化镁过量15%;一定的真空度对反应有促进作用。硫酸酸化实验表明,在一定范围内,温度、真空度和浓硫酸的量均对硫酸化反应起促进作用,较优工艺条件为:硫酸过量15%,温度130℃,真空度为0.05MPa;酸化产物通过XRD分析发现为一水硫酸镁,并非硫酸氢镁。本研究获得的一水硫酸镁中氯含量超过了要求的1%,可利用乙醇的吸水性重结晶提纯,在常温25℃下,p H值控制在1.5以上,硫酸镁初始浓度为1.5mol/L,乙醇的加入量与硫酸镁溶液量的比为1:1(体积),硫酸镁的析出率能达到85%以上,而且氯离子含量小于1%。
[Abstract]:This paper aims at the difficult problem of ammonia nitrogen wastewater treatment in rare earth extraction and separation process, combined with the previous research results of ion rare earth ore without ammonia leaching. The process route of ammonia nitrogen internal circulation concentration, alkali hydrolysis, ammonia making and sulfuric acid acidification to produce hydrochloric acid to control waste and increase efficiency in the process of separation of rare earth elements was designed, and the main links of the innovative process were studied systematically, and the experimental results were found. The solubility of ammonium chloride in rare earth solution decreases with the increase of the concentration of rare earth ions and decreases with the increase of atomic number of rare earth elements at room temperature. When the concentration of ammonium chloride reaches saturation, the kinematic viscosity of the solution increases with the increase of atomic number. The concentration of ammonium chloride does not affect the oil / water phase in rare earth extraction, even in the saturated state of ammonium chloride, the extraction process is not emulsified and difficult to separate. The extraction capacity and extraction separation coefficient of rare earth in saturated state of ammonium chloride are similar to those of conventional process, and the specific gravity of rare earth is smaller than that of light rare earth. The separation coefficient of light rare earth increases with the decrease of feed acidity, but the heavy rare earth is opposite. In addition, saturated ammonium chloride in the stripping acid has no effect on the stripping process. The secondary stripping rate of light rare earth is more than 98%, and the heavy rare earth is about 80%. The alkali hydrolysis experiment shows that the secondary stripping rate of light rare earth is more than 98% and that of heavy rare earth is about 80%. Magnesium hydroxide is suitable for the decomposition of ammonium chloride. The alkali hydrolysis should be carried out at boiling temperature of 103 鈩，

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