Recovery Process And Electrodeposition Mechanism Of Rare Earth Elements In Spent FCC Catalyst

Rare earth elements have unique 4f electronic layer structure,so they have excellent electrical,magnetic and optical properties.They are the supporting materials for the development of sophisticated science and technology and green energy industry.China's rare earth reserves are abundant,the types are relatively complete,and the rare earth industry has made a great progress.Because of the increasing demand for rare earth resources,the cost of using rare earth resources is also increasing,people begin to focus on the recovery and reuse of rare earth resources.The aim is to recover rare earth elements from the waste FCC catalyst in this study.In acid leaching process,the addition of leaching reagent can effectively leach rare earth elements under mild conditions and achieve a higher leaching rate.Furthermore,the recovery of rare earth elements by electrodeposition is achieved by using complexing agents.The recovery of rare earth elements from the waste FCC catalyst is 85.39%,and the purity can reach 96.57%?In this study,the single variable step-by-step optimization method was used to explore the best acid leaching process conditions under the action of the auxiliary agent.Under the optimum process conditions,the total rare earth leaching rate can reach 95.20%,which is 1.40 times of that without the auxiliary agent.Through the analysis of the relationship between the leaching rate of rare earth elements and the leaching temperature and time,the reaction kinetics in the leaching reaction was studied.It was concluded that the reaction of leaching rare aarth elements from spent FCC catalyst under the help of leaching agent belongs to the chemical control,and the corresponding kinetic parameters were obtained,which provides strong guidance for the design of acid leaching process parameters.In order to achieve the effective separation of rare earth elements and non-rare earth elements,and to improve the purity of rare earth recovery,this study used an electrochemical method for electrodeposition recovery.By adding the complexing agent glycine to the aqueous solution,the electrodeposition recovery of rare earth elements is achieved,and a higher recovery rate and purity of rare earth elements are obtained.On this basis,through the single-factor control variable experiment,the best process condition parameters were obtained.Under the optimum conditions:At room temperature(25?),0.05 g/mL ammonium chloride,0.1 g/mL glycine,pH=2.8,current density is 25 mA/cm~2,deposition time 180 min,the recovery of rare earth elements can reach 85.39%,purity 96.57%.In order to clarify the effect of complexing agent on rare earth elements and non rare earth elements,chronopotentiometry was used to explore the influence of complexing agent on the deposition potential.It was found that adding complexing agent can make the deposition potential of rare earth move forward,and at the same time,aluminum and other non rare earth elements with the largest proportion move in an opposite negative direction.As a result,rare earth elements have priority in the same deposition potential In the process of deposition,the non rare earth elements are restrained and retained in the acid leaching solution,thus realizing the effective separation of rare earth and non rare earth elements.Cyclic voltammetry was used to study the electrochemical behavior of the main rare earth ions in the waste catalyst in the aqueous solution with the addition of complexing agent.It was found that the deposition reaction of rare earth elements under the action of complexing agent is a one-step irreversible reaction,which provides a certain reference for the recovery of rare earth from the waste FCC acid leaching solution.To sum up,this study provides a new environmentally friendly,economic and feasible rare earth recovery process,which will contribute to the reasonable recovery and reuse of rare earth resources.