Fractal characteristics of uranium‐bearing sandstone structure and their effects on acid leaching

Zeng, Sheng; Zhang, Ni; Zhang, Shuwen; Sun, Bing; Tan, Kaixuan; Duan, Xianzhe; Du, Xueming

doi:10.1002/ese3.396

Cited by 15 publications

(5 citation statements)

References 36 publications

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“…The internal microstructure of uranium-bearing sandstone is extremely heterogeneous and has been confirmed to have fractal Frontiers in Earth Science frontiersin.org characteristics (Zeng et al, 2019;Zeng et al, 2022). The fractal dimension is usually used to characterize the irregularity of complex structures and can be calculated from the date of HPMIP, which is defined as…”

Section: Test Methodsmentioning

confidence: 99%

Geochemical reactions altering the mineralogical and multiscale pore characteristics of uranium-bearing reservoirs during CO2 + O2in situ leaching

Zhou

Wang²,

Niu³

et al. 2023

Front. Earth Sci.

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CO2 + O2in situ leaching has been extensively applied in uranium recovery in sandstone-type uranium deposits of China. The geochemical processes impact and constrain the leaching reaction and leaching solution migration; thus, it is necessary to study the CO2 + O2–water–rock geochemical reaction process and its influence on the physical properties of uranium-bearing reservoirs. In this work, a CO2 + O2–water–rock geochemical reaction simulation experiment was carried out, and the mineralogical and multiscale pore characteristics of typical samples before and after this simulation experiment were compared by X-ray diffraction and high-pressure mercury intrusion porosimetry (HPMIP). The results show that the CO2 + O2–water–rock geochemical reaction has complicated effects on the mineral compositions due to the various reaction modes and types. After the CO2 + O2–water–rock geochemical reaction, the femic minerals decrease and the clay minerals in the coarse sandstone, medium sandstone, fine sandstone, and siltstone increase, while the femic minerals and clay minerals in sandy mudstone show a contrary changing trend. The CO2 + O2–water–rock geochemical reaction decreases the total pore volume of uranium-bearing reservoirs and then promotes pore transformation from small scale to large scale. The fractal dimensions of macropores are decreased, and the fractal dimensions of mesopores, transition pores, and micropores are increased. The effects of felsic mineral and carbonate dissolution, secondary mineral precipitate, clay mineral swelling, and mineral particle migration are simultaneously present in the CO2 + O2in situ leaching process, which exhibit the positive transformation and the negative transformation for the uranium-bearing reservoirs. The mineral dissolution may improve reservoir permeability to a certain degree, while the siltation effect will gradually reveal with the extension of CO2 + O2in situ leaching. This research will provide a deep understanding of the physical property response of uranium-bearing reservoirs during CO2 + O2in situ leaching and indicate the direction for the efficient recovery of uranium resources.

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Section: Test Methodsmentioning

confidence: 99%

Geochemical reactions altering the mineralogical and multiscale pore characteristics of uranium-bearing reservoirs during CO2 + O2in situ leaching

Zhou

Wang²,

Niu³

et al. 2023

Front. Earth Sci.

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“…This is conditioned by increased filtration characteristics and the intensity of the solution circulation processes. Low values of the sulfuric acid consumption per unit of ore mass in the first experiment, with a standard leaching solution acidity, indicate the presence of residual acidity in the productive solution that has not reacted [20], [21].…”

Section: Figure 3 Uranium Content In the Solution Depending On The Ratio Of L:smentioning

confidence: 98%

Research into leaching of uranium from core samples in tubes using surfactants

Rakishev¹,

Матаев²,

Kenzhetaev³

et al. 2020

Min. miner. depos.

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Improving the efficiency of borehole uranium recovery in difficult mining-and-geological conditions through the development of a new technology based on the intensification of geotechnological processes of in-situ uranium leaching, the selective effect of a new chemical reagents complex on a set of the mineralogical and particle-size distribution of the orebearing rocks of the productive horizon. Methods. Sampling of core material from host rocks of the Syr Darya depression uranium deposit. The content of uranium, calcium, aluminum, iron, magnesium, and carbonate content in the samples has been revealed by the spectral analysis method. The quantitative and qualitative parameters and peculiarities of the host minerals have been determined by the method of X-ray phase analysis. By testing particle-size distribution, the fractional parameters of core samples have been determined. Specifications have been developed, as well as laboratory experiment have been conducted on uranium leaching from core material in a dynamic mode in tubes, with the addition of selected chemical reagents with different modes. Findings. The aspects of borehole uranium recovery using sulfuric acid solutions as a solvent and the reasons that cause a decrease in geotechnological parameters in ores with low filtration characteristics have been determined. An effective method has been developed for intensifying borehole uranium recovery using superficially active substance (surfactants, SAS) in difficult mining-and-geological conditions, with an increased content of argillaceous and carbonate minerals, and low filtration host rocks properties. An efficient and economically feasible method for uranium leaching with sulfuric acid solutions with the addition of surfactants has been revealed and scientifically substantiated. Originality. The scientific novelty is in the fact that the selected surfactants added to sulfuric acid solutions increases the uranium content in the productive solution and the degree of economically feasible uranium recovery with reduced sulfuric acid consumption and the ratio of liquid to solid (L:S). Practical implications. The use of rational surfactants in uranium leaching makes it possible, in areas with low filtration characteristics, to reduce operating expenses for production by reducing the period of recovery, to increase the uranium content in the productive solution and the degree of recovery, as well as to reduce the consumption of sulfuric acid and sedimentation.

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“…The expenses on these methods are relatively higher due to the use of technological equipment and the consumption of chemical reagents. Combined methods include performing complex operations using drilling rigs and auxiliary equipment, combining well flushing with subsequent chemical treatment, swabbing and compressor pumping [15], [16]. This method is the most cost-intensive due to the use of a large number of equipment, chemical reagents, maintenance personnel and a long duration of the works.…”

Section: Figure 3 Location Map Of Regions With Explored Uranium Deposits In Kazakhstanmentioning

confidence: 99%

Methods for intensification of borehole uranium mining at the fields with low filtration characteristics of ores

Kenzhetaev¹,

Nurbekova²,

Togizov³

et al. 2021

Min. miner. depos.

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Purpose. Improving the efficiency of borehole uranium mining and the selection of special decolmating solutions to improve the filtration characteristics of the seam due to effective destruction, as well as by preventing the sedimentation in the productive horizon, depending on the mineralogical composition and structure of sediment-forming materials. Methods. The advantages and disadvantages of the main methods used for improving the filtration characteristics of the productive horizon, when mining the uranium deposits by the borehole method, have been studied. Samples of sedimentation from the productive horizon are taken at the uranium deposit of the Shu-Syrasu depression. The quantitative and qualitative parameters, as well as the peculiarities of the mineral compositions have been determined by the X-ray phase method. A methodology has been developed and laboratory experiments have been conducted on the treatment of sedimentation samples by the drop method using various compositions of selected decolmating solutions. The microscopic method is used to determine the structure and peculiarities of sedimentation before and after treatment with various decolmating solutions. Findings. The effectiveness of the main methods used to improve the filtration characteristics of seams in the uranium deposits, mined by the borehole method, has been determined. The structure and composition of sedimentation, which causes a decrease in the filtration characteristics of the productive horizon, have been determined. To destroy and prevent the sedimentation in the productive horizon, an effective composition of a special decolmating solution using ammonium hydrogen fluoride with the addition of sulphuric acid and surfactants has been selected. An effective method for increasing the filtration characteristics of the productive horizon with the use of special decolmating solutions has been developed and scientifically substantiated. Originality. The use of special decolmating solutions based on ammonium hydrogen fluoride with the addition of sulphuric acid and surfactants according to the developed methodology allows to effectively destroy and prevent sedimentation in the productive horizon of borehole uranium ore mining. Practical implications. The use of the developed decolmating solution and a special methodology for the intensification of borehole uranium mining can reduce the operating costs of its production. This increases the ecological and industrial safety of the work to intensify the leaching of uranium ores.

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Fractal characteristics of uranium‐bearing sandstone structure and their effects on acid leaching

Cited by 15 publications

References 36 publications

Geochemical reactions altering the mineralogical and multiscale pore characteristics of uranium-bearing reservoirs during CO2 + O2in situ leaching

Geochemical reactions altering the mineralogical and multiscale pore characteristics of uranium-bearing reservoirs during CO2 + O2in situ leaching

Research into leaching of uranium from core samples in tubes using surfactants

Methods for intensification of borehole uranium mining at the fields with low filtration characteristics of ores

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