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本文以DTPA-NH_4~+为排代剂,Zn~(2+)作阻滞离子,研究了适用于高压排代时的螯合排代剂组成与稳定区段组成的关系. 根据稀土谱带后沿所进行的螯合反应和置换反应,提出了用稀土滴定排代剂的模拟滴定曲线法.按模拟滴定曲线,可以求得稀土稳定区段中pH和稀土浓度间的关系. 再把模拟滴定曲线法和有效铵浓度的计算式相结合,提出了一种螯合排代工作特性曲线作图法,它把三套坐标:X-Y、X′-Y′、X′-Z(x为螯合度,Y为pH,X′为有效铵浓度,Y′为稀土在树脂相所占百分率,Z为稀土稳定区段的伸长比)结合在一起,求得排代剂组成和工作点的对应关系.用它可以根据排代剂组成求得稳定区段内的pH和稀土浓度、树脂相中稀土所占百分比以及稀土稳定区段的伸长比,从而清楚地阐明了排代剂组成和稳定区段组成间的关系.并可推知,随着NH_4~+(排代离子)的增加,稳定稀土区段中的pH将明显下降,稀土浓度会明显增加,稀土区段达到稳定后的长度会显著增加.
In this paper, DTPA-NH 4 + as a displacing agent and Zn 2+ as a blocking ion were used to study the relationship between the composition of chelating displacer and the composition of stable sections suitable for high-pressure displacement. After the chelation reaction and displacement reaction, the titration curve of titration with rare earth titration reagent was proposed.The relationship between pH and rare earth concentration in the stable zone of rare earth can be obtained according to the simulation titration curves.And then the simulation Titration curve method and the calculation formula of effective ammonium concentration, a chelation displacement working characteristic curve plotting method is proposed. It takes three sets of coordinates: XY, X’-Y ’, X’-Z Degree of compatibility, Y is pH, X ’is effective ammonium concentration, Y’ is the percentage of rare earth in the resin phase, and Z is the elongation ratio of the rare earth stabilized zone) to obtain the correspondence between the composition of the displacer and the working point Relationship.It can be used to determine the composition and stability of the displacing agent according to the composition of the displacing agent to determine the pH and rare earth concentration in the stable section, the percentage of rare earth in the resin phase, and the elongation ratio of the rare earth stabilized section The relationship between the composition of the sections and can be inferred, with the increase of NH_4 ~ + (displacement ions), the stability of the rare earth zone pH Decreased, significantly increase the concentration of rare earths, rare earth segment length to achieve the stability will increase significantly.