晶种加入条件下Ce2（C2O4）3的连续沉淀工艺
Continuous Precipitation Process of Ce2（C2O4）3 Under Addition of Seed Crystals
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摘要: 为了解温度、Ce(NO3)3料液浓度、晶种加入比例和晶种加料区域等工艺条件对Ce2(C2O4)3产品颗粒粒径分布和形貌的影响规律，在杯式沉淀器中采用Ce2(C2O4)3模拟Pu(C2O4)2进行连续沉淀实验研究。保持Ce(NO3)3和草酸的加料区域、沉淀后母液中硝酸和草酸浓度不变，分别考察了30.0~50.0 ℃、Ce(NO3)3浓度为0.084 mol/L和0.167 mol/L、晶种加入比例为0~2.0×10-1和晶种加料区域等工艺条件对Ce2(C2O4)3颗粒粒径分布和形貌的影响。50.0 ℃、Ce(NO3)3浓度为0.167 mol/L，相比无晶种加入时，Ce2(C2O4)3沉淀颗粒D50值（一个样品的累计分布百分数达到50%时所对应的粒径）最大可增加62.2 μm。50.0 ℃、Ce(NO3)3浓度为0.167 mol/L、晶种分别从周边涡流区域和中心涡流区域加入时，对应的D50最大值分别为154.1、120.7 μm。相同工艺条件下，温度为30.0~50.0 ℃时，沉淀颗粒D50最大值随温度的增加而增大。各工艺条件下，当D50达最大值时，Ce2(C2O4)3颗粒以较为规则的片状长条形为主，碎片形和不规则的片状聚集形颗粒所占比例较小。Ce2(C2O4)3晶粒生长方式属于螺旋增长机制，晶粒单层薄片厚度约为16 nm。
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关键词:
- 杯式沉淀器 /
- 连续沉淀 /
- Ce2(C2O4)3 /
- 粒径分布 /
- 形貌
Abstract: In the cup type precipitator, Ce2(C2O4)3 was used to simulate Pu(C2O4)2 for continuous precipitation experiments. Keeping other conditions unchanged, process conditions including temperature at 30.0-50.0 ℃, Ce(NO3)3 concentrations of 0.084 mol/L and 0.167 mol/L, crystal seed addition ratios in the range of 0-2.0×10-1 and seed feeding position were investigated respectively, to find out their effects on the particle size distribution and morphology of Ce2(C2O4)3 particles. When the concentration of Ce(NO3)3 is 0.167 mol/L at 50.0 ℃, the D50 maximum values(D50 is the value of the particle diameter at 50% in the cumulative distribution) of Ce2(C2O4)3 particles can increase by 62.2 μm compared with that without crystal seeds. When the concentration of Ce(NO3)3 is 0.167 mol/L and the crystal seeds are added in the peripheral vortex region and the central vortex region at 50.0 ℃, the corresponding D50 maximum values are 154.1 μm and 120.7 μm respectively. When the temperature changes from 30.0 ℃ to 50.0 ℃, the maximum value of precipitated particles D50 increases with temperature. Under various process conditions, and when D50 reaches the maximum, the shape of Ce2(C2O4)3 particles is dominated by regular flaky long strips, the proportion of fragmented and irregular flaky aggregates is small. The grain growth mode of Ce2(C2O4)3 belongs to the spiral growth mechanism, and the thickness of the single layer of grain is about 16 nm. -
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[1] Vigier N, Grandjean S, Arab-Chapelet B, et al. Reaction mechanisms of the thermal conversion of Pu(Ⅳ) oxalate into plutonium oxide[J]. J Alloys Compd, 2007, 444: 594-597. [2] Rao G S, Subramanian M S, Welch G A. Thermal decomposition of plutonium oxalates[J]. J Inorg Nucl Chem, 1963, 25(10): 1293-1295. [3] 任凤仪，周镇兴.国外核燃料后处理[M].北京：原子能出版社,2006. [4] Poncelet F J, Moulin J P, Hubert Sgn N, et al. Continuous precipitation and filtration, a process technology for liquid waste management [C]∥Tucson, 2001. [5] Moskvin A I, Essen L N. The solubility product of thorium oxalate and the composition and dissociation constants of oxalatocomplexes of thorium in aqueous solution[J]. Russ J Inorg Chem, 1967, 12: 359-362. [6] Leturcq G, Arab-Chapelet B, Bruyker F D, et al. Structural characterization of mixed uranium-plutonium coprecipitates and oxides synthesized by oxalic co-conversion route[C]∥Leturcq G, Arab-Chapelet B, Bruyker F D, et al. Atalante, 2008. [7] 王博，李传博，吕洪彬，等.草酸铈成核和晶体生长动力学[J].核化学与放射化学，2021，43(4)：309-317. [8] Mandleberg C J, Francis K E, Smith R. The solubility of plutonium trifluoride, plutonium tetra fluoride and plutonium(Ⅳ) oxalate in nitric acid mixtures[J]. J Chem Soc, 1961, 475: 2464-2468. [9] Nielsen A E. Nucleation and growth of crystals at high supersaturation[J]. Cryst Res Technol, 1969, 4(1): 17-38. [10] Li C, Wang B, Li X, et al. Studies on nucleation and crystal growth kinetics of plutonium(Ⅳ) oxalate[J]. Radiochim Acta, 2022, 110(2): 87-92. [11] Li C, Ning Y, Yan T, et al. Studies on nucleation and crystal growth kinetics of uranium(Ⅳ) oxalate[J]. Radiochim Acta, 2019, 108(3): 185-193. [12] 郭一飞，梁俊福，刘秉仁，等.草酸钚(Ⅳ)溶解度的研究[J].核化学与放射化学,2001,23(3)：184-188. [13] 李锐柔.核燃料后处理厂钚尾端工艺方案的探讨[J].原子能科学技术，2012,46(9)：188-191. [14] 王锡仁，周安康.锌铝稀土合金中铈的紫外分光光度法测定[J].株冶科技，1990,18(1)：41-44. [15] 李传博，宁勇智，晏太红，等.杯式连续沉淀器中草酸亚铁的沉淀工艺[J].核化学与放射化学，2020，42(2)：92-101. [16] 尹华伟，李明伟，曹亚超，等．ZTS晶体(100)面生长过程的实时AFM研究[J].材料导报,2017,31(12)：15-20.
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