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›› 2002, Vol. 2 ›› Issue (4): 0-0.

• 4 •    

超重力反应沉淀法制备碳酸钙的过程与形态控制

陈建峰，刘润静，沈志刚，宋继瑞，初广文   

  1. 北京化工大学教育部超重力工程研究中心，北京100029
  • 出版日期:2002-08-20 发布日期:2002-08-20

Mechanism of Extracting Zinc and Cadmium with Thiophosphoric

ZHANG Da-li1, KE Jia-jun2 , LU Li-zhu2   

  1. 1. Biochemical Engineering College of Beijing Union University, Beijing 100023, China;2. Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100080, China)
  • Online:2002-08-20 Published:2002-08-20

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摘要： 采用pH计、电导率仪、XRD原位检测了超重力反应沉淀法制备轻质碳酸钙的碳化过程及其动力学. 研究发现，碳化反应前期二氧化碳吸收为控制步骤，碳化反应后期转化为Ca(OH)2溶解控制. 同时发现在碳化过程前期有一明显的凝胶化现象，此时的pH值和电导率出现突变. XRD显示，此时有新相生成. 由于超重力环境下可以极大强化二氧化碳传质速率和微观混合，碳化时间较传统的“碳化法”缩短4倍以上. 结合过程控制，通过选择不同的工艺操作参数和相应的晶形控制剂，可以有选择性地控制碳酸钙的成核和生长，成功地合成了具有不同粒径的立方、链锁、纺锤、针状、片状、球形、花瓣、纤维等8种不同形态的碳酸钙粒子.

关键词: 超重力, 碳酸钙, 形态控制, 合成

Abstract: In the extraction of zinc and cadmium with di-(2-ethlhexyl)-dithiophosphoric acid(D2EHDTPA)–primary amine N1923 or di-(2-ethlhexyl)-monothiophosphoric acid(D2EHMTPA)–primary amine N1923, the dependence of the percentage extraction on pH was comparatively abnormal, which was probably caused by primary amine N1923 reacting with H2SO4 and aggregating into reversed micelle. If the empirical formula of the N1923–H2SO4 adduct is expressed by (N1923)n.H2SO4, the ratio n between N1923 and H2SO4 was about 3 in most cases of our research, which might be related to stereoscopic effects. The extraction mechanism was proved as follows:M2+(a)+2BHA(o) + (2/n)SO42–(a) = MA2(o) + (2/n)(Bn.H2SO4)(o) + 2(1–2/n)H+(a) , n=3, 4, 5.

Key words: thio-substituted organophosphorus acid, primary amine N1923, solvent extraction, zinc, cadmium, reversed micelle

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