氨法一步沉淀法制备碱式碳酸锌结晶行为特征

研究了锌氨配离子溶液一步法制备碱式碳酸锌晶体的结晶行为。以锌氨配离子溶液中[Zn²⁺]_T的迁移轨迹为基础, 研究不同工艺参数条件对制备碱式碳酸锌结晶率与晶体粒径的影响。试验结果表明, 蒸氨开始10~50 min为前驱体碱式碳酸锌晶核形成期, 反应温度越高结晶速率越快, 体系中氨的含量越高晶核粒径越小。结晶50 min后, 为晶核生长期, 前驱体晶体粒径快速增大, 温度越高晶体生长速率越快。在80 ℃、搅拌速度400 r/min、Zn²⁺浓度2.6 mol/L的条件下, 蒸氨50 min制得碱式碳酸锌晶核平均粒径为180 nm。此外, 采用匀速滴加碳酸氢铵溶液能减缓碱式碳酸锌晶体生长速率, 晶核平均粒径小于120 nm。

Characteristics of Crystallization Behavior of Basic Zinc Carbonate in Preparation by Ammonia Process

An investigation was made on the crystallization behavior of basic zinc carbonate in the preparation using zinc-amino coordination ion solution by one-step precipitation method. The effects of different process conditions on crystallization rate and crystal grain size were studied based on the trajectory of [Zn²⁺]_T in the zinc-amino coordination ion solution. The results showed that the crystal nuclei of basic zinc carbonate precursor formed during the early 10~50 min period in ammonia stilling process. The crystallization speed will become faster with the rise of temperature, while the size of crystal nucleus will become smaller with the increasing of the ammonia concentration. After 50-minute crystallization, the nuclei was in a growth stage. The crystal grain size of the precusor increased sharply. With a stirring speed at 400 r/min, Zn²⁺ content of 2.6 mol/L and ammonia still time of 50 min, the average grain size of the crystal nuclei obtained was 180 nm. In addition, adding ammonium bicarbonate solution at a uniform velocity could decrease the growth rate of the zinc carbonate crystals, with an average size less than 120 nm.