Study Of Occurrence Characteristics And Enrichment Mechanism Of HREE In Zoujiashan Uranium Deposit,Jiangxi Province

The uranium ore of the Zoujiashan uranium deposit shows a good ability to enrich heavy rare earth elements?HREE?.Part of enriched HREE can reach to the industrial grade.Therefore,it is an important frame work to study the occurrence characteristics and enrichment mechanism of HREE in the Zoujiashan uranium deposit.In the paper,a series of experiments are carried out for the study of the occurrence characteristics and enrichment mechanism of HREE,such as the field geological investigation,petrography,electron probe analysis,elemental geochemistry,mineral microregion analysis,automatic mineral analysis,X-ray diffraction,the water-rock reactions,and the adsorption experiments of some common clays,etc.Additionally,the interdisciplinary research for the metallogenic regularity and the metallogenic system of ore deposits is also applied to demonstrate the occurrence characteristics and enrichment mechanism of HREE.Based on these studies,some important results are achieved as follows:?1?Geochemical analysis of the Zoujiashan uranium deposit indicates that:the HREE is significantly enriched by the uranium ore.The content of HREE is positively correlated with CaO,TiO₂,and P₂O₅,while it is negatively correlated with SiO₂,Al₂O₃,Na₂O and K₂O,and positively correlated with trace elements which including U,Th,Mo,LREE,Pb,Sr,Nb,Ta,W,F,and Ta.?2?Based on the study for the occurrence characteristics of REE in Zoujiashan uranium ore,several important results are achieved and listed as follow:?1?The dispersed phase of REE that is as isomorphism hosts in the uranium ore and apatite,etc;?2?Most of the independent REE minerals are xenotime,and only small amount of monazite are found in the uranium ore.The main size of xenotime particles is small,which associated with the uranium ore,apatite and sericite.?3?The adsorption phase of REE ions mainly hosts in clay minerals.?3?From two aspects of REE extraction and enrichment has been studied REE enrichment mechanism of Zou Jiashan uranium deposit:?1?The rate value in the acid environment is higher than that in the alkaline environment,while both of them are higher than that in the distilled water environment.The leaching effects of Na⁺and K⁺on the?REE+Y in alkaline solution are similar,however,K⁺is more beneficial for the HREE leaching than that of Na⁺under the same conditions.?2?The adsorption and enrichment experiments of REE verifies that the adsorption rate of clay minerals to the rare earth is montmorillonite?91.32%?>kaolinite?73.85%?>chlorite?61.07%?>illite?35.65%?,and the adsorption rates of kaolin and illite on HREE are higher than that of LREE,while montmorillonite and chlorite is opposite.?4?The HREE in the Zoujiashan uranium deposit is mainly the migration of the halogen?F,Cl?complex and phosphate complex,while carbonate and sulfate have no significant contribution to the migration of rare earth elements.The HREE experiences 3 enrichment stages:the first stage is the full evolution of the magma,which provides the material basis for the early HREE enrichment;the second stage is that the hydrothermal fluid of mineralization dominated by the high temperature,alkaline and residual hydrothermal fluid of the rich Na,forms a sodium metasomatic uranium ore with the enriched light rare earth;and the third stage is the hydrothermal fluid of mineralization dominated by the red basin brine with the rich K,forms a fluorite-illite uranium ore with the enriched heavy rare earth.It is firstly discovered that the uranium ore in the Zoujiashan ore deposit enriches the HREE,part of which has reached to the industrial grade.It is also found that the heavy rare earth elements exist in the form of the dispersed phase,mineral phase and ion adsorption phase.The source,migration and enrichment mechanism of the heavy rare earth are discussed in detail.Besides,the preliminary water rock experiment indicates that the leaching rate of the heavy rare earth elements has reached over 60%when the uranium is leached.In the future,the leaching rate of HREE will be further improved based on the optimizing the leaching conditions of uranium ore.Therefore,it is a great promising for the comprehensive utilization of the uranium and HREE.