The Basic Research Of Micro-fluid Extraction Of Light Rare Earths By Synergistic Cooperation

Currently,the extraction separation process of rare earth is mainly carried out in the mixer-settler with the utilization of P507 as the primary extracting agent.However,this kind of process has a lot of problems,such as long mixing time,large land occupation,and high energy consumption.This paper brings forward a new microfluidic extraction separation method for the separation of rare earth in the presence of lactic acid and citric acid,achieving an "efficient,green,and safe"extraction process.In this paper,microfluidic technology is adopted to study the light rare earth elements(La,Ce,Pr and Nd)extraction separation with the utilization of lactic acid and citric acid as complexing agent.The influence of various factors on the extraction parameters is studied to gain the clean new technology of extraction;then the reaction mechanism and mass transfer process in a microreactor are mainly studied to reveal the essential of extraction and separation of rare earths.The main results are summarized as follows:(1)Firstly,we have studied the influence of different factors on basic parameters in the extraction separation process.The results show that the separation factors of Ce/La,Pr/Ce and Nd/Pr increase with the increase of pH and channel length,while increase with increasing time till remain constant.Besides,with the increase of the width,the separation factors are decreased,Under the best experimental conditions(flow velocity 9.38?L/min,pH 2.25,the width 300?m,the length 50cm),the maximum separation factors of Ce/La,Pr/Ce and Nd/Pr are 9.50,4.03,and 2.34 respectively,which are higher than those in the current industrial saponification system.(2)Secondly,we have studied the reaction mechanism between extractant and REEs using slope method,UV spectrum,FT-IR spectrum,NMR spectrum and MS spectrum.The results are listed as follows:Lac' and H2cit-would not participate in the extraction reaction;and the reaction lechanisl between P507and RE3+ is cation exchange,which means one rare earth ion reacts with three P507 dimer to produce RE(HA2)3 complex and three H+.(3)Finally,we have studied the two-phase flow characteristics and mass transfer of microfluidic extraction.The results are shown as follows:with the increase of chip width,the two-phase flow pattern gradually changes from stable plug flow to droplet flow,then into a laminar flow.Besides,the specific interfacial area increases with an increase of flow velocity,then remain constant;and it decreases with an increase of chip width,increases with increasing chip length(in the range of 3000?10600m2/m3);lastly,the volumetric mass transfer coefficient increases with an increase of flow velocity,decreases with an increase of chip width(in the range of 0.02?0.45s-1).Thus,it can be seen that these findings are expected to provide theoretical foundation for realizing clean and efficient rare-earth extraction process,and promoting the industrialization of microfluid extraction technology in rare earth industry under cooperative complexing effect.According to these researchs that pH,reaction time,width and length of the chip have the effects on separation of the rare earth,and these can give some advice on the research later.