摘要
副产物连二硫酸锰(MnS_(2)O^(6))的生成是限制软锰矿烟气脱硫技术广泛工业化应用的关键科学问题。迄今,MnS_(2)O^(6)的生成机制尚未阐明,难以为控制MnS_(2)O^(6)的生成提供有效的理论依据。本文采用理论分析与实验验证相结合的方法研究了SO_(2)浸出软锰矿体系MnS_(2)O^(6)的生成机制,阐明了MnS_(2)O^(6)生成速率的控制步骤和动力学过程。首先,通过文献研究对反应体系进行了理论分析,并基于SO_(2)氧化的HSO_(3)自由基机理及表面吸附和电化学模型提出的SO_(2)还原浸出二氧化锰(MnO_(2))的动力学模型,提出MnS_(2)O^(6)的生成机制可用HSO_(3)自由基生成机理进行解释,MnS_(2)O^(6)生成速率微观上取决于HSO_(3)生成速率,宏观上主要取决于体系H^(+)和HSO_(3)^(-)浓度,理论推导的生成速率方程为RMnS_(2)O_(6)=k·[H^(+)],H^(+)和HSO_(3)^(-)的理论反应级数均为1.0。然后,通过动力学实验研究考察了体系SO_(2)浓度、pH和温度对MnS_(2)O^(6)生成的影响和动力学过程,结果表明:MnS_(2)O^(6)生成速率随体系SO_(2)浓度的增大而增加,随体系酸度和温度的升高呈现先快速减小后下降趋缓的趋势,H^(+)和SO_(2)浓度对MnS_(2)O^(6)生成速率的反应级数分别为–0.059和1.014,反应活化能为7068.98 J/mol。最后,结合动力学实验研究结果和SO_(2)溶解平衡分析,推导出体系H^(+)浓度和HSO_(3)^(-)浓度的反应级数分别为0.955和1.014,与理论推导出的反应级数非常接近。研究结果验证了理论分析所得动力学方程的准确性,表明MnS_(2)O^(6)生成机制可用HSO_(3)自由基生成机理进行解释,可为MnS_(2)O^(6)生成特性及抑制方法研究提供理论依据和有效途径。
The formation of manganese dithionate is the key scientific issue limiting the extensive industry application of flue gas desulfurization with pyrolusite.So far,the formation mechanism of manganese dithionate has not been clarified,which is difficult to provide effective theoretical guides for controlling manganese dithionate formation.The rate-controlling steps and dynamic process of manganese dithionate formation for pyrolusite leaching process with sulfur dioxide waste gas has been clarified in this paper based on the combination of theoretical analysis and experimental verification.Firstly,the reaction system was analyzed theoretically through literature studies,based on the free radical production mechanism of SO_(2)oxidation and the reduction leaching kinetics model derived from surface complexation and electrochemical model were proposed.The formation mechanism of manganese dithionate can be proposed based on HSO_(3)free radical formation mechanism,which has manifested that the formation rate of manganese dithionate was depended on the production rate of HSO_(3)free radical in microscopic scales,and can be determined by H^(+)and HSO_(3)^(-)concentration in macroscopic view.The derived theoretical equation for manganese dithionate formation could be reported as follows RMnS_(2)O^(6)=k·[H^(+)],[HSO_(3)^(-)],the reaction orders with respect to H^(+)and HSO_(3)^(-)both were 1.0.Then,the effects of SO_(2)concentration,pH and temperature on manganese dithionate formation and dynamical processes were explored through dynamic experiments,the results showed that the manganese dithionate formation rate was decreased rapidly firstly,and then decreased easing up with pH and temperature,while raised under higher SO_(2)concentration conditions,the calculated apparent activation energies for manganese dithionate formation was 7068.98 J/mol,the reaction orders with respect to H^(+)and SO_(2)concentration were–0.059 and 1.014,respectively.Finally,in combination with dynamical results and dissolution equilibrium analysis
作者
何克杰
苏仕军
丁桑岚
孙维义
HE Kejie;SU Shijun;DING Sanglan;SUN Weiyi(School of Architecture and Environment,Sichuan Univ.,Chengdu 610065,China;School of Chemistry and Environmental Eng.,Chongqing Univ.of Arts and Sci.,Chongqing 402160,China)
出处
《工程科学与技术》
EI
CSCD
北大核心
2023年第3期194-199,共6页
Advanced Engineering Sciences
基金
国家自然科学基金项目(51374150)
重庆市教育委员会科学技术研究项目(KJQN201901307)
重庆市科学技术委员会项目(cstc2021jcyj-msxmX1005)
重庆文理学院校级科研项目(R2019FCH09)。
关键词
二氧化硫
软锰矿
连二硫酸锰
生成机制
动力学
sulfur dioxide
pyrolusite
manganese dithionate
formation mechanism
dynamic
