铁离子对磷酸氢二铵结晶过程的影响

Effect of Fe^(3+) on Crystallization Process of Diammonium Phosphate

首先,采用动态激光法测定了不同铁离子含量的磷酸氢二铵溶液结晶介稳区的宽度;其次,借助倒置显微镜,通过单晶生长法来研究铁离子对磷酸氢二铵晶体生长速率的影响;此外,还通过对产品粒度分布的分析,考察了掺杂铁离子对磷酸氢二铵颗粒大小的影响。实验结果发现:随着铁离子质量浓度百分数由0增加至0.007,结晶介稳区宽度由3.32℃增大到7.68℃。随着Fe^(3+)质量浓度百分数的增大,单晶各个方向的生长速率都逐渐减小。当Fe^(3+)质量浓度百分数X(Fe^(3+))=0.005时,在过饱和度△C=6 g·(100 g)^(-1)的溶液中,磷酸氢二铵晶体x方向的生长速率G_x由未添加Fe^(3+)时的60.29 nm·s^(-1)减小为28.35 nm·s^(-1);平均粒径D50由不加Fe^(3+)时267.1μm减小到137.6μm;40~80目的晶体粒子体积分率,由未掺杂时的88.85%减小到48.75%。产品粒度分布的重复性下降。

First of all,the crystallization metastable zone width of diammonium phosphate（ DAP） solution with different contents of iron ions（ Fe^3＋） was determined by dynamic laser method. Secondly,the effect of Fe^3＋on the growth rate of DAP was studied by single crystal growth method with inverted microscope.In addition,the effect of Fe^3＋on the regularity of DAP particles was investigated by analyzing the particle size distribution. The experimental results show that with the increasing of Fe^3＋concentration from 0 to0. 007,metastable zone width increases to 7. 68 ℃ from 3. 32 ℃,the growth rate of the single crystal in all directions is reduced gradually. When the percentage of iron ion mass concentration X（ Fe^3＋） = 0.005,the crystal rate of x direction of diammonium phosphate（ Gx） decreases from 60. 29 nm·s^-1（ no adding Fe^3＋） to 28. 35 nm·s^-1in the solution with the degree of supersaturation △C = 6 g·（ 100 g）^-1,and the average particle diameter D50 decreases from 267. 1 μm（ no adding Fe^3＋） to 137. 6 μm and the crystal particle volume fraction of 40-80 mesh is reduced from 88. 85%（ not adding Fe^3＋） to 48. 75%.The repeatability of the product particle size distribution declines.