COMPARISON OF THE DISSOLUTION CHARACTERISTICS OF FE-BEARING MINERALS BEFORE AND AFTER CO2+O2 PRESSURE STIRRING LEACH-ING OF THE MENGQIGUER URANIUM DEPOSIT,XINJIANG
Fe-bearing minerals are prevalent in sandstone type uranium deposits and have a significant im-pact on in-situ leaching.This article uses CO2+O2 pressure stirring leaching experiment,TESCAN Inte-grated Mineral Analysis(TIMA)and Scanning Electron Microscopy(SEM)to characterize the associa-tion,liberation,and grain size changes of Fe-bearing minerals before and after in-situ leaching of gray coarse-grained sandstone ore in Mengqiguer uranium deposit.The aim is to analyze the behavior of Fe-bearing minerals during neutral in-situ leaching and to reveal the impacts on uranium leaching.The results shows that the association of pyrite,biotite,and siderite decreased from 18.82％,2.77％and 0.04％to 0.00％after leaching,while chlorite changed from 2.56％to 3.56％and 0.00％;The liberation of four minerals mainly distributed in the range of less than 1％before and after leaching.There is a decreasing trend in liberation of chlorite,biotite,and pyrite except siderite.Concerning grain size,the grain size pro-portion of chlorite,biotite,pyrite,and siderite between 5 μm and 15 μm increased after leaching,indica-ting a reduction in grain size.In summary,chlorite,biotite,pyrite,and siderite will undergo dissolution during CO2+O2 in-situ leaching,and the released Fe2+is converted into Fe3+,benefiting for the oxidation of U4+and potentially forming iron precipitates or colloids that could obstruct the ore layer,adsorb U6+,and reduce uranium leaching efficiency.The concentration of Fe3+and pH are key factors affecting urani-um leaching,and their controlled adjustment holds significant guidance for actual production.
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