Abstract: In view of the hazardous characteristics of waste flue gas SCR catalyst, such as leaching toxicity, etc, the ministry of environmental protection clearly put wasted SCR catalyst into hazardous waste management. At the same time, the wasted catalyst contains high-value components of vanadium, tungsten and titanium, so the research of the recycling technology about waste SCR catalyst has become a hotspot in the field of environmental protection in recent years. The method of sodium roasting can destroy the original structure of wasted catalyst, and improve the leaching rate by the phase changing of vanadium and tungsten. The process is simple and easy to control, so it has widely applicability. In 2012, Kim et al. adopted sodium roasting-water leaching process to recover vanadium and tungsten, and studied the mechanism of roasting process. However, the mechanism of V-W leaching has not been studied. The purpose of this work is to explore the reaction mechanism of the leaching process after sodium roasting of wasted SCR catalyst, study the control conditions of the reaction process, and further study the kinetics of the leaching process. Thus, the leaching process of vanadium and tungsten is revealed, which is contribution to provide the theoretical basis for improving the economy of leaching. The analytical method of XRD and SEM were used to study the phase and morphology of the roasted samples. Based on this, the kinetic model of leaching process was designed, the leaching equation of reaction process was deduced, and the parameters of the leaching equation were deduced through the experimental results of leaching process. The results showed that the roasted samples are in the form of columnar sintered phase and acicular non sintered phase, and the two phases are almost completely separated. Vanadium and tungsten mainly exist in the columnar sintered phase, so it is suitable for direct water leaching to dissolve vanadium and tungsten. According to the shape and hypothesis of calcination, the kinetic equation of leaching process was derived by using the “column non end condensation model”, and the function relationship between leaching rate and time was obtained. Through single factor experiment, the best leaching conditions were determined as follows: liquid-solid ratio 3∶1, leaching temperature 80 ℃, stirring rate 350 r/min, time 30—40 min, at this point, the recovery of tungsten and vanadium were 90.07% and 84.57%, respectively; Through the relationship between recovery and leaching time, the relationship between leaching rate and time was converted, and the leaching kinetics equation of vanadium and tungsten was derived: ηV=-0.001 05t2+0.066 2t+0.014 66 and ηw=-0.001 00t2+0.064 12t+0.014 91.
刘子林, 林德海, 何发泉, 曹子雄, 王宝冬. 钠化焙烧法回收废SCR催化剂中钒和钨的浸出机理及浸出动力学研究[J]. 材料导报, 2021, 35(Z1): 429-433.
LIU Zilin, LIN Dehai, HE Faquan, CAO Zixiong, WANG Baodong. Study of Leaching Mechanism and Kinetics of Vanadium and Tungsten on the Process of Recovery Spent SCR Catalyst by Sodium Roasted. Materials Reports, 2021, 35(Z1): 429-433.
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