钯在硝酸高铈铵溶液中的溶解工艺及宏观动力学研究  

Study on dissolution process and kinetics of palladium in Ce(NH_4)_2(NO_3)_6 solution

作　　者：燕展鹏 刘明辉 薛天艳[2] 于颖 张中苇 杜嬛[2] 肖清贵[2] 张绘 齐涛[2,3,4] Zhanpeng YAN;Minghui LIU;Tianyan XUE;Ying YU;Zhongwei ZHANG;Xuan DU;Qinggui XIAO;Hui ZHANG;Tao QI(School of Chemical Engineering,Zhengzhou University,Zhengzhou,Henan 450001,China;National Engineering Research Center of Green Recycling for Trategic Metal Resources,Institute of Process Engineering,Chinese Academy of Sciences,Beijing 100190,China;School of Chemical Engineering,University of Chinese Academy of Sciences,Beijing 100049,China;Ganjiang Innovation Academy,Chinese Academy of Sciences,Ganzhou,Jiangxi 341000,China)

机构地区：[1]郑州大学化工学院,河南郑州450001 [2]中国科学院过程工程研究所国家战略金属资源绿色回收工程技术研究中心,北京100190 [3]中国科学院大学化学工程学院,北京100049 [4]中国科学院赣江创新研究院,江西赣州341000

出　　处：《过程工程学报》2023年第4期554-561,共8页The Chinese Journal of Process Engineering

基　　金：国家重点研发计划资助项目(编号:2021YFC2902602);中国科学院前沿科学重点研究项目(编号:QYZDJ-SSW-JSC021);在渝高校与中科院所属院所合作项目(编号:HZ2021013)。

摘　　要：钯(Pd)是重要的战略金属,具有优异的理化性质,广泛应用于石油化工、汽车制造、航空航天和电子信息等领域。因其自然储量低,难以满足社会发展的需求,研究含钯二次资源回收技术,实现金属钯的循环利用具有重要意义。本工作针对传统湿法回收钯技术存在的酸耗高、NO_(x)排放量大等问题,提出了环境友好的硝酸高铈铵浸出新体系,考察了浸出剂浓度、酸度、添加剂浓度、反应温度、搅拌速度等因素对钯粉在硝酸高铈铵溶液中的溶解率的影响。结果表明,金属钯在混合体系中的溶解受到Pd表面吸附的显著影响。在没有Cl^(-)的情况下,金属钯表面吸附氧或者吸附NO_(3)^(-)形成了表面钝化,阻碍了Ce^(4+)与Pd原子的反应,5 h溶出率仅为0.2%。添加Cl^(-)后,通过竞争吸附能够有效破坏表面钝化层,构成突破点,从而加速钯的溶解反应。NO_(3)^(-)与Cl^(-)构成竞争吸附,更高浓度的硝酸根需要更高浓度的Cl^(-)启动溶解反应。优选浸出反应条件如下:硝酸高铈铵浓度1mol/L、硝酸浓度1 mol/L、盐酸浓度0.03 mol/L、反应温度80℃、搅拌速度200 r/min,在该条件下反应1.5 h钯粉的溶解率达到100%。钯粉在硝酸高铈铵溶液中的溶解过程符合化学反应控制的反应核缩减模型,表观活化能为58.7 kJ/mol,动力学方程为1-(1-x)^(1/3)=2264806e^(-58732/RT)t。As an important strategic reserve metal,palladium (Pd) is widely used in chemical,automotive catalysts,aerospace and electronic products due to its excellent physical and chemical properties.However,due to the lack of mineral resources,it is difficult to meet the needs of social development,so it is of great significance to study the secondary recovery process of Pd to realize the recycling of Pd.In this work,a new leaching system of Ce(NH_4)_2(NO_3)_6 was proposed to solve the problems existing in the traditional leaching system.The dissolution behavior of Pd powder in acidic Ce(NH_4)_2(NO_3)_6 solution was studied in detail.The results showed that the dissolution of metallic Pd in the mixed system was significantly affected by the adsorption on the Pd surface.In the absence of Cl-,the surface of metallic palladium was passivated by the adsorption of oxygen or NO_3-on the surface,which hindered the reaction between Ce~(4+)and Pd atoms since the dissolution ratio was only 0.2%in 5 h.The addition of Cl-was helpful to destroy the surface passivation layer through competitive adsorption and accelerated the dissolution reaction of Pd.The NO_3-and Cl-constituted competitive adsorption,and higher concentrations of nitrate required higher concentrations of Clto initiate the dissolution reaction.The effects of different reaction conditions on the dissolution efficiency of Pd powder were investigated.The results showed that the efficiency of the dissolution of Pd powder reached 100%after1.5 h at the concentration of Ce(NH_4)_2(NO_3)_6 of 1 mol/L,HNO_3 of 1 mol/L,Cl~-of 0.03 mol/L,reaction temperature of 80℃and stirring speed of 200 r/min,which was the preferences condition of the dissolution of Pd powder.The dissolution kinetics of Pd powder in acidic Ce(NH_4)_2(NO_3)_6 solution showed that the dissolution reaction of Pd powder in solution conformed to the shrinking core model controlled by chemical reaction.The apparent activation energy of the dissolution reaction was 58.7 kJ/mol,and the kinetic equation was 1-(1-x)~(

关 键 词：钯 溶解 硝酸高铈铵 氯离子 

分 类 号：TF836[冶金工程—有色金属冶金]