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Yongfan Guo - One of the best experts on this subject based on the ideXlab platform.
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thermodynamic modeling of in Situ Leaching of sandstone type uranium minerals
Journal of Chemical & Engineering Data, 2020Co-Authors: Nao Shen, Yongfan GuoAbstract:In Situ Leaching (ISL) is the main mining method for sandstone-type uranium deposits. The thermodynamic model can provide important information to real project decision making. However, systematic thermodynamic modeling work is still lacking for uranium-containing systems. In this paper, a thermodynamic model for the uranium minerals–solution–gas system is established with reliable and internal consistent parameters. The B-dot model and Peng–Robinson model are used to calculate the activity coefficients and fugacity coefficients. The determination for the equilibrium constant is carried out based on the comparisons between the calculated results by this model and the experimental solubility data. The solubility of uranium minerals under different experimental conditions can be reproduced by this model. Tetravalent uranium minerals are less soluble than hexavalent uranium minerals in the absence of oxidants, especially under alkaline conditions. The dissolution of uranium mineral assemblages, including pit...
Nao Shen - One of the best experts on this subject based on the ideXlab platform.
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thermodynamic modeling of in Situ Leaching of sandstone type uranium minerals
Journal of Chemical & Engineering Data, 2020Co-Authors: Nao Shen, Yongfan GuoAbstract:In Situ Leaching (ISL) is the main mining method for sandstone-type uranium deposits. The thermodynamic model can provide important information to real project decision making. However, systematic thermodynamic modeling work is still lacking for uranium-containing systems. In this paper, a thermodynamic model for the uranium minerals–solution–gas system is established with reliable and internal consistent parameters. The B-dot model and Peng–Robinson model are used to calculate the activity coefficients and fugacity coefficients. The determination for the equilibrium constant is carried out based on the comparisons between the calculated results by this model and the experimental solubility data. The solubility of uranium minerals under different experimental conditions can be reproduced by this model. Tetravalent uranium minerals are less soluble than hexavalent uranium minerals in the absence of oxidants, especially under alkaline conditions. The dissolution of uranium mineral assemblages, including pit...
Yin Peng-bo - One of the best experts on this subject based on the ideXlab platform.
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Analysis and evaluation on hydrogeological conditions of in-Situ Leaching in Shihongtan sandstone-type uranium deposit
World Nuclear Geoscience, 2008Co-Authors: Yin Peng-boAbstract:Hydrogeological conditions for in-Situ Leaching in Shihongtan sandstone-type uranium deposit are analyzed,the favorable and unfavorable factors for in-Situ Leaching uranium are evaluated. It is indicated geochemically that the traditional acid and alkaline Leaching methods are not suitable for Shihongtan uranium deposit,some proposals and ideas on uranium Leaching methods are put forward.
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Influences of permeabilities of ore-bearing layer on the in-Situ Leaching of uranium
World Nuclear Geoscience, 2008Co-Authors: Yin Peng-boAbstract:The permeability of ore-bearing layer in sandstone-type uranium deposit is considered as the decisive condition whether the in-Situ Leaching technology for uranium deposit is feasible or not. It is quite significant to study the feasibility of in-Situ Leaching for uranium deposit so as to improve the permeability of the sandstone-type uranium deposit. The paper systematically summarizes that the major factors influencing the permeability of ore-bearing layer,i.e. carbonate,clay minerals,impermeable bed,intercalated bed,grade of salinity of the groundwater. The results provide a theoretical basis for the further study on improving the permeability of sandstone. This is theoretically significant and practically valuable to improve the Leaching rate of uranium and the recovery of resources.
Kai Xuan Tan - One of the best experts on this subject based on the ideXlab platform.
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Prediction model of uranium concentration for in-Situ Leaching pregnant solution based on uranium chemical fractions of ores
Journal of Radioanalytical and Nuclear Chemistry, 2018Co-Authors: Kai Xuan Tan, Liangshu Xia, Zhenzhong Liu, Wanyu Tan, Liang ChenAbstract:Based on the uranium chemical fractions, combined with laboratory experiments and field monitoring data, a prediction model of uranium concentration for in Situ Leaching pregnant solution was established. It was demonstrated that the kinetics of in Situ Leaching of uranium is affected by four chemical fractions from exchangeable to oxidizable after the acidification stage, meanwhile the variation of uranium concentration with time displays two trends as high → low and low → high → low, moreover, it is basically consistent with the fourth-order polynomial relationship. The prediction model equation is yi,x= aix4+ bix3+ cix2+ dix + ei, among which the parameters can be obtained by the regression of uranium chemical fractions of ores.
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Chemical Speciations of Uranium of a Sandstone Uranium Deposit and their Effects to In Situ Leaching, Northwest China
Advanced Materials Research, 2014Co-Authors: Liang Chen, Kai Xuan Tan, Hu Yang, Yan Shi Xie, Wei Huang, Zheng Qing WangAbstract:The chemical speciations of uranium of a sandstone uranium deposit in the Yili Basin were quantitative analyzed using the method of sequential chemical extraction, and the implications of which for in-Situ Leaching of uranium were discussed. The proportion of chemical speciations of uranium shows that the bound to carbonates>the bound to Fe-Mn oxides>the exchangeable>the residual>the bound to sulfide-organic matter speciation, which is beneficial to cost reduction on in-Situ Leaching of uranium and environmental protection. The active uranium includes 4 chemical speciations except for the residual speciation is principal, which suggests that the Leaching rate of uranium of the sandstone uranium deposit is high. The inert uranium is the residual speciation, with low proportion. The sample with high proportion of active uranium is of high grade, and vice versa, which indicates that the ratio of total uranium extracted/reserves should be relatively high. Hence, based on the chemical speciations of uranium, the sandstone uranium deposit can be exploited suitably using the technique of in-Situ Leaching with dilute sulfuric acid, integrated considering that cost control of in-Situ Leaching of uranium, environmental protection, Leaching rate of uranium and the ratio of total uranium extracted/reserves of uranium.
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Effect of a Complex Surfactant on In Situ Leaching of Low Permeable Sandstone Uranium Deposits
Volume 4: Codes Standards Licensing and Regulatory Issues; Fuel Cycle Radioactive Waste Management and Decommissioning; Computational Fluid Dynamics (, 2012Co-Authors: Kai Xuan Tan, Jiang Liu, Yongxiang HuangAbstract:The effect of a complex surfactant on in Situ Leaching of low permeable sandstone uranium deposits is discussed, based on an Agitation Leaching and a column Leaching experiments. The results of the Agitation Leaching experiment show that adding different concentrations surfactant into Leaching solutions increases significantly the Leaching rate of uranium. For a surfactant concentration of 10 mg/l, the Leaching rate of uranium reaches maximum 92.6%. The results of the column Leaching experiment show that adding 10mg/L surfactant into Leaching solutions increases the permeability coefficient of ore-bearing layer 28.8% and the Leaching rate of uranium 58.0%, resulting in 85.79%. The results of kinetic analysis show that extraction of uranium is controlled by diffusion with apparent rate constant of 0.0023/d without adding surfactant and by surface chemical reaction with apparent rate constant of 0.0077/d with adding surfactant. Thus, for low permeable sandstone uranium deposit, the in Situ Leaching mining is of great potential if adding the complex surfactant into Leaching solutions.Copyright © 2012 by ASME
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nonlinear dynamics of flow reaction coupling in porous media and application to in Situ Leaching uranium mining
International Journal of Modern Physics B, 2004Co-Authors: Kai Xuan Tan, Qingliang Wang, Zehua LiuAbstract:When a reactive fluid flows through a porous rock it can dissolve some minerals and increase the porosity and permeability. The positive feedback between fluid flow and mineral dissolution can lead to the complexity of the propagation of dissolution front and the formation of finger flow-focusing reaction area. As an example for in Situ Leaching Uranium mining, the simulation results indicate that the propagation of dissolution front is complex such as finger and more complicated reaction front morphologies. The nonlinearity of flow-reaction coupling and instability of dissolution front morphologies can lead to unLeaching area and affect the rate of recovery of mineral resource.
Richard E Weyers - One of the best experts on this subject based on the ideXlab platform.
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in Situ Leaching method for determination of chloride in concrete pore water
Cement and Concrete Research, 2006Co-Authors: Leonardo Caseres, Alberto A Sagues, S C Kranc, Richard E WeyersAbstract:In the in Situ Leaching (ISL) method, pore water ionic content is determined in small cavities drilled in mortar/concrete specimens. Prior investigations have demonstrated the ISL applicability to obtain pH and nitrite ion concentration in concrete/mortar pore water. The application of the method is extended here to determine pore water chloride ion concentration (and pH) within practical test times in mortars and concretes prepared in the laboratory and in concrete cores extracted from a bridge deck in deicing salt service. Spatial resolution for the determination of composition profiles is also illustrated. Modeling of the ISL process indicates that chloride binding accelerates the approach toward a terminal cavity concentration, reducing test duration to practical lengths for moderate permeability concretes. This acceleration can be attributed to maintaining a higher gradient of free chloride near the cavity wall due to the release, during Leaching, of previously bound chloride. Consequently, there is a faster chloride buildup in the cavity water compared with the no-binding case. Experimental chloride and pH results obtained by the ISL test in mortar samples show good agreement with those from the pore water expression (PWE) method. Also, examples are presented of application of ISL data to obtain chloride binding isotherms, and pore water chloride to hydroxide ratio relevant to assessing conditions for corrosion of steel reinforcement. The ISL method presents a less costly and less disruptive alternative to PWE for pore water analysis. It is noted, however, that in a few instances ISL could not be implemented because of excessive absorption of cavity water by the surrounding medium.