Clay minerals are inferred to be the primary host materials for ion-exchangeable rare earth in ion adsorption type rare earth ore(IAREO).During the rare earth leaching process,the adsorption and desorption reactions o...Clay minerals are inferred to be the primary host materials for ion-exchangeable rare earth in ion adsorption type rare earth ore(IAREO).During the rare earth leaching process,the adsorption and desorption reactions of the cations controlling the leaching process continue to occur at the clay minerals-leaching agent solution interface.In order to understand the leaching mechanism and behavior of rare earth and co-leached aluminum,adsorption,competitive adsorption,and desorption experiments were carried out using kaolin as a typical clay mineral.The powerful electrostatic attraction and concentration driving forces facilitate the adsorption of cations.The adsorption ability and competitive adsorption ability of cations depend on their charge,hydration radius,and hydrolysis properties,and decrease in the order of La^(3+),Y^(3+),Al^(3+),Mg^(2+),and NH_(4)^(+).The desorption of rare earth and aluminum is positively affected by the concentration-driving force exerted by high concentrations of Mg^(2+) and NH_(4)^(+),with the order of the desorption ability being opposite to the adsorption ability.However,unspecified interactions between clay mineral particles enhanced by high-concentration desorbents,especially by Mg^(2+) than NH_(4)^(+),will adversely affect desorption reactions,which result in lower desorption efficiencies of rare earth and aluminum obtained with magnesium sulfate compared to those obtained with ammonium sulfate at high concentrations.Solid-phase Al(OH)_(3) generated at a high peak aluminum concentration leads to a considerably delayed aluminum efflux,thereby partially separating the rare earth from aluminum during the actual column leaching process.To advance the mining technology of IAREO by selectively improving the rare earth leaching efficiency with minimal leaching agent consumption,higher charged cations with concentrations limited to suitable levels should be preferred as leaching agents.展开更多
基金supported by the National Key Research and Development Project of China (2021YFC2902202,2020YFC1909002,2019YFC0605002)National Natural Science Foundation of China (51604128)+1 种基金The Youth Jinggang Scholars Program in Jiangxi Province (QNJG2019056)The cultivation project of the State key Laboratory of Green Development and High-value Utilization of Ionic Rare Earth Resources in Jiangxi Province (20194AFD44003)。
文摘Clay minerals are inferred to be the primary host materials for ion-exchangeable rare earth in ion adsorption type rare earth ore(IAREO).During the rare earth leaching process,the adsorption and desorption reactions of the cations controlling the leaching process continue to occur at the clay minerals-leaching agent solution interface.In order to understand the leaching mechanism and behavior of rare earth and co-leached aluminum,adsorption,competitive adsorption,and desorption experiments were carried out using kaolin as a typical clay mineral.The powerful electrostatic attraction and concentration driving forces facilitate the adsorption of cations.The adsorption ability and competitive adsorption ability of cations depend on their charge,hydration radius,and hydrolysis properties,and decrease in the order of La^(3+),Y^(3+),Al^(3+),Mg^(2+),and NH_(4)^(+).The desorption of rare earth and aluminum is positively affected by the concentration-driving force exerted by high concentrations of Mg^(2+) and NH_(4)^(+),with the order of the desorption ability being opposite to the adsorption ability.However,unspecified interactions between clay mineral particles enhanced by high-concentration desorbents,especially by Mg^(2+) than NH_(4)^(+),will adversely affect desorption reactions,which result in lower desorption efficiencies of rare earth and aluminum obtained with magnesium sulfate compared to those obtained with ammonium sulfate at high concentrations.Solid-phase Al(OH)_(3) generated at a high peak aluminum concentration leads to a considerably delayed aluminum efflux,thereby partially separating the rare earth from aluminum during the actual column leaching process.To advance the mining technology of IAREO by selectively improving the rare earth leaching efficiency with minimal leaching agent consumption,higher charged cations with concentrations limited to suitable levels should be preferred as leaching agents.
