With weathering crust Ion-Absorbed Type Rare Earth （IATRE） ores in southern Jiangxi as an example, rare earth percolation leaching and leaching solution precipitation process research were carried out under conditio...With weathering crust Ion-Absorbed Type Rare Earth （IATRE） ores in southern Jiangxi as an example, rare earth percolation leaching and leaching solution precipitation process research were carried out under conditions of magnetic field. The effect on the rare earth leaching process such as magnetic field strength, magnetization time, magnetization manner, and other factors were discussed. The effect on the mother rare earth liquor sedimentation rate, purity, and crystallization behavior such as magnetic field strength, magnetization time, and magnetization manner were investigated. Leaching and precipitation mechanism of magnetization on IATRE were analyzed. The results showed that the magnetic treatment can improve leaching rate of weathering crust IATRE and the sedimentation rate, and reduce consumption of reagents.展开更多
Ameliorating the problem of low leaching efficiency,long leaching period,and high agent consumption should be studied to efficiently exploit ion-absorbed rare earth ore resources.In this study,the surfactant sodium do...Ameliorating the problem of low leaching efficiency,long leaching period,and high agent consumption should be studied to efficiently exploit ion-absorbed rare earth ore resources.In this study,the surfactant sodium dodecyl sulfate(SDS) is used to enhance the leaching effect of an ion-absorbed rare earth ore by ameliorating the seepage effect for the first time.The effects of surfactant concentration,leaching agent dosage,solution flow velocity,and solution pH on the leaching rate were explored,and the mechanism of SDS was discussed.Under the optimum conditions,the addition of a small amount of SDS(mass fraction0.04%) can increase the leaching rate by about 5%,shorten the leaching period,and reduce the consumption of the leaching agent.SDS significantly ameliorates the seepage effect of the ore body by reducing the surface tension of the leaching agent and ameliorating the wettability of the mineral surface.This effect is the main factor that improves the leaching efficiency.DFT(density functional theory) calculation results show that SDS can react with rare earth ions,which reduces the adsorption strength on clay mineral surfaces.Hence,rare earth ions are easily exchanged by ammonium ions,and mass transfer is enhanced.展开更多
The magnesium sulfate leaching technology for the ion-absorbed rare earths ore can solve the ammonia pollution problem existing in ammonium sulfate leaching process. However, the leaching capacity of magnesium sulfate...The magnesium sulfate leaching technology for the ion-absorbed rare earths ore can solve the ammonia pollution problem existing in ammonium sulfate leaching process. However, the leaching capacity of magnesium sulfate is slightly weaker than that of ammonium sulfate, resulting in a bigger consumption of magnesium sulfate. In this paper, the MgSO4-ascorbic acid compound leaching agent had been demonstrated to deal with the ion-absorbed rare earths ore. The ascorbic acid could form a stable coordination with rare earth ions, so that it can strengthen the leaching of ion-exchangeable phase.Moreover, ascorbic acid has a strong reductive property, it can leach the colloidal sediment phase rare earth as well. The present study investigates the effect of the initial pH and the composition of leaching agent on the rare earth leaching. It is determined that the rare earth leaching efficiency is 107.5% under the condition of pH 2.00,0.15 mol/L magnesium sulfate and 1.0 g/L ascorbic acid in leaching agent. In this case, the content of the ion-exchangeable phase and colloidal sediment phase rare earth in the leaching residues are both only 0.02‰. The leaching efficiency of colloid sediment phase rare earth can be 85.7%,so that the Ce partition in the leaching liquor increases to be 5.77%. The magnesium-ascorbic acid compound leaching agent is proposed to be a promising choice to deal with the ion-absorbed rare earths ore, which can realize the efficient leaching, low consumption of MgSO4 and environmentally friendly leaching.展开更多
Ion-absorbed rare earth mines,leached in situ,retain a large amount of ammonium nitrogen(NH4–N)that continuously releases into the surrounding environments.However,quantitative descriptions and predictions of the tra...Ion-absorbed rare earth mines,leached in situ,retain a large amount of ammonium nitrogen(NH4–N)that continuously releases into the surrounding environments.However,quantitative descriptions and predictions of the transport of NH4–N across mining area with hill slopes are not fully established.Here,laboratory column experiments were designed with an inclined slope(a sand box)to examine the spatial temporal transport of NH4–N in soils collected from the ionic rare earth elements(REE)mining area.An HYDRUS-2D model simulation of the experimental data over time showed that soils had a strong adsorption capacity toward NH4–N.Chemical non-equilibrium model(CNEM)could well simulate the transport of NH4–N through the soil-packed columns.The simulation of the transport-adsorption processes at three flow rates of leaching agents revealed that low flow rate enabled a longer residence time and an increased NH4-N adsorption,but reduced the extraction efficiency for REE.During the subsequent rainwater washing process,the presence of slope resulted in the leaching of NH4–N on the surface of the slope,while the leaching of NH4–N deep inside the column was inhibited.Furthermore,the high-intensity rainfall significantly increased the leaching,highlighting the importance of considering the impact of extreme weather conditions during the leaching process.Overall,our study advances the understanding of the transport of NH4–N in mining area with hills,the impact of flow rates of leaching agents and precipitation intensities,and presents as a feasible modeling method to evaluate the environmental risks of NH4–N pollution during and post REE in situ mining activities.展开更多
基金the Natural Science Foundation of Jiangxi Province (0050009)
文摘With weathering crust Ion-Absorbed Type Rare Earth （IATRE） ores in southern Jiangxi as an example, rare earth percolation leaching and leaching solution precipitation process research were carried out under conditions of magnetic field. The effect on the rare earth leaching process such as magnetic field strength, magnetization time, magnetization manner, and other factors were discussed. The effect on the mother rare earth liquor sedimentation rate, purity, and crystallization behavior such as magnetic field strength, magnetization time, and magnetization manner were investigated. Leaching and precipitation mechanism of magnetization on IATRE were analyzed. The results showed that the magnetic treatment can improve leaching rate of weathering crust IATRE and the sedimentation rate, and reduce consumption of reagents.
基金supported by the National Natural Science Foundation of China (Nos. 51774153 and 92062110)。
文摘Ameliorating the problem of low leaching efficiency,long leaching period,and high agent consumption should be studied to efficiently exploit ion-absorbed rare earth ore resources.In this study,the surfactant sodium dodecyl sulfate(SDS) is used to enhance the leaching effect of an ion-absorbed rare earth ore by ameliorating the seepage effect for the first time.The effects of surfactant concentration,leaching agent dosage,solution flow velocity,and solution pH on the leaching rate were explored,and the mechanism of SDS was discussed.Under the optimum conditions,the addition of a small amount of SDS(mass fraction0.04%) can increase the leaching rate by about 5%,shorten the leaching period,and reduce the consumption of the leaching agent.SDS significantly ameliorates the seepage effect of the ore body by reducing the surface tension of the leaching agent and ameliorating the wettability of the mineral surface.This effect is the main factor that improves the leaching efficiency.DFT(density functional theory) calculation results show that SDS can react with rare earth ions,which reduces the adsorption strength on clay mineral surfaces.Hence,rare earth ions are easily exchanged by ammonium ions,and mass transfer is enhanced.
基金Project supported by Program of National Natural Science Foundation of China(51604128)China Postdoctoral Science Foundation(2017M620279)Key projects of the major Research and Development Program of Jiangxi Province(20171ACE50008)
文摘The magnesium sulfate leaching technology for the ion-absorbed rare earths ore can solve the ammonia pollution problem existing in ammonium sulfate leaching process. However, the leaching capacity of magnesium sulfate is slightly weaker than that of ammonium sulfate, resulting in a bigger consumption of magnesium sulfate. In this paper, the MgSO4-ascorbic acid compound leaching agent had been demonstrated to deal with the ion-absorbed rare earths ore. The ascorbic acid could form a stable coordination with rare earth ions, so that it can strengthen the leaching of ion-exchangeable phase.Moreover, ascorbic acid has a strong reductive property, it can leach the colloidal sediment phase rare earth as well. The present study investigates the effect of the initial pH and the composition of leaching agent on the rare earth leaching. It is determined that the rare earth leaching efficiency is 107.5% under the condition of pH 2.00,0.15 mol/L magnesium sulfate and 1.0 g/L ascorbic acid in leaching agent. In this case, the content of the ion-exchangeable phase and colloidal sediment phase rare earth in the leaching residues are both only 0.02‰. The leaching efficiency of colloid sediment phase rare earth can be 85.7%,so that the Ce partition in the leaching liquor increases to be 5.77%. The magnesium-ascorbic acid compound leaching agent is proposed to be a promising choice to deal with the ion-absorbed rare earths ore, which can realize the efficient leaching, low consumption of MgSO4 and environmentally friendly leaching.
基金the Financial of National Key Research and Development Project of China(No.2019YFC1805102)Partial supports are from the National Natural Science Foundation of China(Nos.42107228 and 41977266)Shanghai Pujiang Program(No.21PJ1401000)。
文摘Ion-absorbed rare earth mines,leached in situ,retain a large amount of ammonium nitrogen(NH4–N)that continuously releases into the surrounding environments.However,quantitative descriptions and predictions of the transport of NH4–N across mining area with hill slopes are not fully established.Here,laboratory column experiments were designed with an inclined slope(a sand box)to examine the spatial temporal transport of NH4–N in soils collected from the ionic rare earth elements(REE)mining area.An HYDRUS-2D model simulation of the experimental data over time showed that soils had a strong adsorption capacity toward NH4–N.Chemical non-equilibrium model(CNEM)could well simulate the transport of NH4–N through the soil-packed columns.The simulation of the transport-adsorption processes at three flow rates of leaching agents revealed that low flow rate enabled a longer residence time and an increased NH4-N adsorption,but reduced the extraction efficiency for REE.During the subsequent rainwater washing process,the presence of slope resulted in the leaching of NH4–N on the surface of the slope,while the leaching of NH4–N deep inside the column was inhibited.Furthermore,the high-intensity rainfall significantly increased the leaching,highlighting the importance of considering the impact of extreme weather conditions during the leaching process.Overall,our study advances the understanding of the transport of NH4–N in mining area with hills,the impact of flow rates of leaching agents and precipitation intensities,and presents as a feasible modeling method to evaluate the environmental risks of NH4–N pollution during and post REE in situ mining activities.
