Leaching calcium from phosphogypsum desulfurization slag by using ammonium chloride solution: Thermodynamics and kinetics study

作     者：Yanjun Zhong Ting Shi Qiuge Chen Xiushan Yang Dehua Xu Zhiye Zhang Xinlong Wang Benhe Zhong Yanjun Zhong;Ting Shi;Qiuge Chen;Xiushan Yang;Dehua Xu;Zhiye Zhang;Xinlong Wang;Benhe Zhong

作者机构：School of Chemical EngineeringEngineering Research Center of Comprehensive Utilization and Clean Processing of Phosphorus Resources of Ministry of EducationSichuan UniversityChengdu 610065China 

出 版 物：《Chinese Journal of Chemical Engineering》 (中国化学工程学报（英文版）)

年 卷 期：2020年第28卷第1期

页      面：208-215页

核心收录：

学科分类：081702[工学-化学工艺] 08[工学] 0817[工学-化学工程与技术] 

基　　金：Supported by Young Teachers Scientific Research Foundation Project of Sichuan University(2014SCU11020) National Key Research Project(2017YFB0307504) Sichuan Science and Technology Planning Project(2019YFH0149) 

主　　题：PG desulfurization slag Leaching process Thermodynamics Kinetic model 

摘      要：Phosphogypsum(PG) desulfurization slag is a calcium-rich residue from reductive decomposition of PG using sulfur as the reductant. We proposed a technology of preparation light calcium carbonate with PG desulfurization slag, which mainly contains two steps: leaching and carbonizing. In this work, we concentrated on the former, in which ammonium chloride aqueous solution was utilized as leaching agent to extract calcium from the slag, and conducted thermodynamics and kinetics study on it. Fact Sage software was employed to do thermodynamic and phase equilibrium diagram calculations. The influence of leaching conditions including agitation speed, initial concentration of leaching solution, reaction temperature, and liquid/solid ratio on the calcium leaching rate was discussed in detail by means of experiment optimal design. A kinetic model developed from the shrinking core model was given to describe the leaching process. The apparent kinetic activation energy(Ea) of the leaching reaction was calculated to be 10.58 kJ·mol^-1.