Identification And Evaluation Of Key Characteristics Of Solid Waste Containing Rare Earth

Rare earth elements are important strategic metals widely used in electronics and new energy industries because of their special optical and electromagnetic properties.To ensure the safety of rare earth supply,many countries have issued relevant policies to promote the resource utilization of industrial solid waste containing rare earths.The main solid waste containing rare earths in urban mines is electronic waste.Because of its wide range of sources,changeable composition,complex structure,and unclearly understanding of key characteristics,the utilization rate of resources is low.Therefore,this study takes e-waste as the research object,makes an in-depth study on all metal phases covered,and establishes a comprehensive benefit evaluation system for the resource utilization of e-waste.Based on this,a priority evaluation model of metal resources utilization in e-waste is constructed,which provides a quantitative evaluation method and theoretical basis for low-carbon and efficient utilization of rare earth solid waste in urban mines.The main research contents are as follows:(1)Collect and sort out the characteristics of metal composition in e-waste from three aspects: metal types,the morphology of existing compounds or mixtures,and crystal structure,and construct the metal composition feature mapping map of the key components of e-waste.The principle of statistical entropy is introduced to evaluate the disorder degree of metal components in the key components of e-waste.The results show that the metal composition similarity between the key components of e-waste with relatively simple metal composition is higher.To construct the relationship between the symmetry of metal crystal structure and its function in electronic waste,the results show that there are more non-centrosymmetric crystals in the metal compounds or mixtures which depend on the piezoelectric effect,pyroelectric effect,electro-optic effect,and electromagnetic effect.(2)The comprehensive benefit evaluation index system of e-waste resource utilization is established according to the economic-environmental-energy benefits.The weight of each index is determined by the Entropy method to evaluate and analyze the comprehensive benefit of waste LCD monitors and waste LED monitors resource utilization.The results show that the comprehensive benefit of waste LCD monitors resource utilization is higher.(3)The priority evaluation model of metal resource utilization in e-waste is established by Entropy weight-Topsis method,and the resource utilization priority of rare earth elements in waste LCD monitors and waste LED monitors is evaluated and analyzed.The results show that the comprehensive benefit of resource utilization of rare earth elements in waste LCD monitors is higher.The priority of resource utilization of rare earth elements in waste LCD monitors from high to low is Eu,Y,Tb,Pr,Ce,and La.And the priority of resources utilization of rare earth elements in waste LCD display is significantly lower than other metals in it.