THE OCCURRENCE CHARACTERISTICS OF URANIUM MINERALS IN QIANJIADIAN SANDSTONE-TYPE URANIUM DEPOSIT AND ITS EFFECT ON EFFICIENCY OF NEUTRAL(CO2+O2)IN-SITU LEACHING OF URANI-UM
The occurrence characteristics of uranium minerals in leachable sandstone-type uranium ore di-rectly influence their contact chemical reaction with the leaching agent.Therefore,it is crucial to elucidate the variations in the distribution of uranium minerals during the leaching process to comprehensively en-hance the leaching rate of uranium.In this study,samples from the IV ore section of the Qianjiadian sand-stone-type uranium deposit were collected for laboratory leaching experiments.Observations using the SEM-EDS microscope and TESCAN Integrated Mineralogy Analysis were con-ducted to quantitatively analyze the characteristics of uranium mineral distribution,dissociation degree,associated minerals,and particle size changes before and after the leaching reaction.The results indicate that the independent uranium minerals in the Qianjiadian sandstone-type uranium deposit are primarily composed of pitchblende with a small amount of coffinite.The dissociation of completely enveloped pitch-blende and coffinite increases from 61.06％to 68.17％and from 46.88％to 58.27％,respectively.This suggests that the change in the dissociation parameter of pitchblende is significantly greater than that of coffinite,indicating that pitchblende is more prone to oxidation dissolution.The particle sizes of pitch-blende and coffinite are mostly in the range of 6 to 12 μm and 4 to 10 μm,respectively,and are associated with feldspar,quartz,pyrite,mica,clay minerals,etc.,which typically act as coating materials on urani-um minerals,creating difficulties for uranium minerals to contact and react with the leaching solution.Af-ter leaching,a substantial number of uranium minerals remain inside the detrital particles of quartz and feldspar.Only small particles(5 μm)of coffinite remain at the edges of these associated particles,indica-ting that fully coated uranium minerals are challenging to leach under CO2+O2 leaching conditions.Addi-tionally,the leaching experiment shows that the leaching effect of pitchblende is higher than that of coffin-ite.This study's results have revealed the geochemical properties of uranium minerals,and their spatial distribution and co-occurrence relationships to the associated minerals affect the U leaching efficiency dur-ing the CO2+O2 in-situ leaching.It provides a new insight for the targeted allocation of leaching agents,such as the addition of environmentally friendly H2O2,to dissolve and oxidize insoluble uranium minerals,such as coffinite.
Qianjiadian sandstone type uranium depositCO2+O2 leachinguranium mineralsoccur-rence characteristics
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