Experimental investigation of dynamic characteristics of leaching tubing for solution mining of salt cavern carbon and energy storage

Salt caverns are extensively utilized for storing various substances such as fossil energy,hydrogen,compressed air,nuclear waste,and industrial solid waste.In China,when the salt cavern is leached through single-well water solution mining with oil as a cushion,engineering challenges arise with the leaching tubing,leading to issues like damage and instability.These problems significantly hinder the progress of cavern construction and the control of cavern shape.The primary cause of this is the flowinduced vibration instability of leaching tubing within a confined space,which results in severe bending or damage to the tubing.This study presents a model experimental investigation on the dynamic characteristics of leaching tubing using a self-developed liquid-solid coupling physical model experiment apparatus.The experiment utilizes a silicone-rubber pipe(SRP)and a polycarbonate pipe(PCP)to examine the effects of various factors on the dynamic stability of cantilevered pipes conveying fluid.These factors include external space constraint,flexural rigidity,medium outside the pipe,overhanging length,and end conditions.The experiments reveal four dynamic response phenomena:water hammer,static buckling,chaotic motion,and flutter instability.The study further demonstrates that the length of the external space constraint has a direct impact on the flutter critical flow velocity of the cantilevered pipe conveying fluid.Additionally,the flutter critical flow velocity is influenced by the end conditions and different external media.

Efficient removal of Al(Ⅲ)and P507 from high concentration MgCl_(2)solution based on in-situ reaction strategy

For a highly efficient recycling of a wastewater containing a high concentration of MgCl_(2),Al(Ⅲ)and P507 were scheduled to be removed in advance.In this study,the in-situ removal of Al(Ⅲ)and P507 from a high concentration MgCl_(2)solution at different pH values and Al/P molar ratios was investigated.The results showed that P507 formed organic complexes of Al_(x)(OH)_y^(Z+)-P507 at pH of 2.0-4.0.At pH of 4.0-5.0,Al(Ⅲ)precipitated and transferred into Al(OH)_(3)with a flocculent amorphous morphology.Active sites on the Al(OH)_(3)surface enhanced the removal efficiency of P507.At pH of 6.0-6.5,Al(Ⅲ)and Mg(Ⅱ)formed layered crystalline Al(OH)_(3)and MgAl_(2)(OH)_(8with)small pore channels and fewer active sites,resulting in a reduced removal efficiency of P507.When the Al/P molar ratio exceeded 13 and the pH was between 4.0 and 5.0,the removal rates of both Al(Ⅲ)and P507 were higher than98%,while the concentration loss of Mg(Ⅱ)was only 0.2%-0.9%.

Analytical solution for stress and deformation of the mining floor based on integral transform

Following exploitation of a coal seam, the final stress field is the sum of in situ stress field and an excavation stress field. Based on this feature, we firstly established a mechanics analytical model of the mining floor strata. Then the study applied Fourier integral transform to solve a biharmonic equation,obtaining the analytical solution of the stress and displacement of the mining floor. Additionally, this investigation used the Mohr–Coulomb yield criterion to determine the plastic failure depth of the floor strata. The calculation process showed that the plastic failure depth of the floor and floor heave are related to the mining width, burial depth and physical–mechanical properties. The results from an example show that the curve of the plastic failure depth of the mining floor is characterized by a funnel shape and the maximum failure depth generates in the middle of mining floor; and that the maximum and minimum principal stresses change distinctly in the shallow layer and tend to a fixed value with an increase in depth. Based on the displacement results, the maximum floor heave appears in the middle of the stope and its value is 0.107 m. This will provide a basis for floor control. Lastly, we have verified the analytical results using FLAC3 Dto simulate floor excavation and find that there is some deviation between the two results, but their overall tendency is consistent which illustrates that the analysis method can well solve the stress and displacement of the floor.

Hazard development mechanism and deformation estimation of water solution mining area

Based on the hazard development mechanism, a water solution area is closely related to the supporting effect of pressure-bearing water, the relaxing and collapsing effect of orebody interlayer, the collapsing effect of thawless material in orebody, filling effect caused by cubical expansibility of hydrate crystallization and uplifting effect of hard rock layer over cranny belt. The movement and deformation of ground surface caused by underground water solution mining is believed to be much weaker than that caused by well lane mining, which can be predicted by the stochastic medium theory method. On the basis of analysis on the engineering practice of water solution mining, its corresponding parameters can be obtained from the in-site data of the belt water and sand filling mining in engineering analog approach.

In-situ pH Measurement at the Electrode/Solution Interface

In this paper a pH microprobe technique was developed to measure in-situ the pH value at the electrode/solution interface. Iridium oxide was used as a pH sensitive material with good response behavior in the measured solutions. The experimental results indicated that the interfacial pH increased with the applied potential, first jumped to a maximum, then slowly decreased at the controlled potential during the electrodeposition process of functional ceramics.

Eutectic Solution Enables Powerful Click Reaction for In-Situ Construction of Advanced Gel Electrolytes

Thiol-ene click reaction is an intriguing strategy for preparing polymer electrolytes due to its high activity,atom economy and less side reaction.However,the explosive reaction rate and the use of non-electrolytic amine catalyst hamper its application in in-situ batteries.Herein,a nitrogen-containing eutectic solution is designed as both the catalyst of the thiol-ene reaction and the plasticizer to in-situ synthesize the gel polymer electrolytes,realizing a mild in-situ gelation process and the preparation of high-performance gel electrolytes.The obtained gel polymer electrolytes exhibit a high ionic conductivity of 4×10^(−4)S cm^(−1)and lithium-ion transference number(t_(Li)^(+))of 0.51 at 60°C.The as-assembled Li/LiFePO_(4)(LFP)cell delivers a high initial discharge capacity of 155.9 mAh g^(-1),and a favorable cycling stability with the capacity retention of 82%after 800 cycles at 1 C is also obtained.In addition,this eutectic solution significantly improves the rate performance of the LFP cell with high specific capacity of 141.5 and 126.8 mAh g^(-1)at 5 C and 10 C,respectively,and the cell can steadily work at various charge–discharge rate for 200 cycles.This powerful and efficient strategy may provide a novel way for in-situ preparing gel polymer electrolytes with desirable comprehensive performances.

IN-SITU TIME-RESOLVED RAMAN SPECTROSCOPIC STUDIES OF SILVER ELECTRODE IN NaSCN SOLUTION

In-situ time-resolved Raman spectroscopy(TRRS)has been applied on studies of electrochemical adsorption of thiocyanate at silver electrode during potential cycles and potential step.It is shown that some dynamic information about the adsorption and desorption processes can be obtained.

In-situ Elimination Effect on Heavy Metals in Contaminated Soil from the Mining Area by Ramie

[Objective] The aim was to study on in-situ elimination effect on heavy metals in soil of the mining area by ramie （Boehmeria nivea （L.） Gaud.）. [Methods] Based on Xiangzhu No.3 and Zhongzhu No.1, we conducted research on heavy metals contents of plants growing in soil of Qibao Mountain orefield in Liuyang, Hunan Province, and on characteristics of enrichment and transfer of heavy metals （Cu, Pb, Cd, Zn） under influence of the two ramie species. [Result] It was concluded that trend of Cu content in different parts of ramie was as follows： rootskinleafbone; trend of Pb was rootleafskinbone; trend of Cd was rootskinboneleaf; the trend of Zn was rootskinboneleaf. In farmland A （with low content of heavy metal）, for per square meter of plough horizon, effect of Zhong 1 on heavy metals transferring volume and the period for restoration of the soil into national standard one （Category Ⅲ of Environmental Quality Standard for Soil） have been concluded. Specifically, for Cu, the corresponding values were 3 404.44 mg and 8.59 y, respectively; for Pb, the values were 3 638.5 mg and 13.52 y; for Cd, the values were 720.48 mg and 1.49 y; for Zn, the values were 37 324.8 mg and 0.67 y. [Conclusion] Soil contaminated by Cu, Pb, Cd, and Zn in orefield can be rapidly restored by growing ramie.

Remediation of in-situ Leach Mining Contaminated Soil by Amendment-plant Synergism

This study aimed to remediate in-situ leach mining contaminated soil by amendment-plant synergism. The results showed that plant species exhibited ex-tremely significant effects on the concentration of nitrate nitrogen; to be specific, the concentration of nitrate nitrogen in soil planted with wheat was reduced from 692.19 mg/kg to lower than 100 mg/kg; when the mass ratio of amendment to soil reached 3：50 and the amendment particle size was 1-2 mm, the concentration of nitrate ni-trogen in soil planted with wheat was reduced to 43 mg/kg. The amendment type exhibited extremely significant effects on the concentration of ammonium nitrogen; to be specific, when the mass ratio of amendment to soil reached 10：50, the concen-tration of ammonium nitrogen in soil added with 2-3 mm zeolite was reduced from 23 593.75 to 3 300 mg/kg on day 15. Amendments and plants mainly exhibited desorption performance for sulfate radical in soil, and the amendment type extreme-ly significantly affected the concentration of sulfate radical; to be specific, the con-centration of sulfate radical in soil added with limestone increased from 370 mg/kg to 900 mg/kg on day 7.

Fluidized mining and in-situ transformation of deep underground coal resources: a novel approach to ensuring safe, environmentally friendly, low-carbon, and clean utilisation

Traditional coal mining and utilisation patterns are severely detrimental to natural resources and environments and significantly impede safe, low-carbon, clean, and sustainable utilisation of coal resources. Based on the idea of in situ fluidized coal mining that aims to transform solid coal into liquid or gas and transports the fluidized resources to the ground to ensure safe mining and low-carbon and clean utilisation, in this study, we report on a novel in situ unmanned automatic mining method. This includes a flexible, earthworm-like unmanned automatic mining machine (UAMM) and a coal mine layout for in situ fluidized coal mining suitable for the UAMM. The technological and economic advantages and the carbon emission reduction of the UAMM-based in situ fluidized mining in contrast to traditional mining technologies are evaluated as well. The development trends and possible challenges to this design are also discussed. It is estimated that the proposed method costs approximately 49% of traditional coal mining costs. The UAMM-based in situ fluidized mining and transformation method will reduce CO2 emissions by at least 94.9% compared to traditional coal mining and utilisation methods. The proposed approach is expected to achieve safe and environmentally friendly coal mining as well as lowcarbon and clean utilisation of coal.

Influence of solution concentration and temperature on the dissolution process and the internal structure of glauberite

Although transport in porous media under the influence of chemistry and temperature is a common phenomenon, the dissolution and internal structure evolution of glauberite during in-situ mining have been unique and challenging. This uniqueness indicates the complexity of mineral dissolutions, whereas the challenge represents the characterization of pore development and evolution during the dissolution processes. To investigate the microstructure development of glauberite under the influence of chemistry and temperature, experimental studies were performed with fine cuboid specimens of 4 mm × 4 mm × 9 mm soaked in solutions of different concentrations(fresh water, half-saturated, and saturated brine). The evolutions of internal structures were monitored through a micro computed tomography system. The statistical analysis indicated that the concentration and temperature of solutions significantly influenced the evolutions of pore size, porosity, and specific surface area of glauberite. The results showed that the increase in the rates of pore size, porosity, and specific surface area declined with time when glauberite was saturated in fresh water. The main reason for pore parameter variation is the differential concentration of solution. However, in the half-saturated and saturated solutions, the increase in rate increased with time. These observations suggest that the chloride ions contained in the saline solution could facilitate the dissolution of glauberite, whereas the existence of salt effect could contribute to the dissolution of calcium sulfate. Compared with the results at 20?C and 65?C, the studied parameters of glauberite have dramatically decreased when the mineral was soaked in the solutions at high temperature(95?C). This function was most striking in fresh water. The dissolution of glauberite soaked in fresh water or half-saturated brine solution was conditioned by the temperature and solution concentration. However, the dissolution of glauberite was less influenced by temperature at high concentrations. These findings may feature significant implication for the effective recovery of mineral resources by in-situ solution mining method.

Numerical simulation of oil shale in-situ mining using fluid-thermo-solid coupling

For the in-situ gas-injection mining technology of oil shale by process,a numerical simulation method with flow-thermo-solid coupling is proposed in this paper.This method adopts separate simulations and step-by-step coupling simulation ideas combined with the advantages of the finite element method and the finite volume method.The numerical simulation of flow-thermo-solid coupling is decomposed into two parts:flow-solid coupling and thermo-solid coupling.Considering the Fuyu oil shale in-situ production test area in Songliao Basin as an example,it is concluded that the oil shale has undergone four heating stages:a rapid temperature rise,a steady temperature rise,a slow temperature rise,and heat preservation.It takes about 10 years for the stress-strain state of the oil shale layer to reach a steady-state through the thermo-solid coupling.The main strain zones of the oil shale layer are distributed near the fracturing fractures connected to the gas injection well and at the edge of the fracturing fractures.The areas with the plastic deformation in the oil shale layer predominantly appear near the gas injection wells,production wells,and fracturing channels.The areas with the largest fracture strength are mostly distributed near the edge of the fracturing fractures with low flow velocity and low temperature.

Solute drag-controlled grain growth in magnesium investigated by quasi in-situ orientation mapping and level-set simulations

Critical properties of metallic materials,such as the yield stress,corrosion resistance and ductility depend on the microstructure and its grain size and size distribution.Solute atoms that favorably segregate to grain boundaries produce a pinning atmosphere that exerts a drag pressure on the boundary motion,which strongly affects the grain growth behavior during annealing.In the current work,the characteristics of grain growth in an annealed Mg-1 wt.%Mn-1 wt.%Nd magnesium alloy were investigated by advanced experimental and modeling techniques.Systematic quasi in-situ orientation mappings with a scanning electron microscope were performed to track the evolution of local and global microstructural characteristics as a function of annealing time.Solute segregation at targeted grain boundaries was measured using three-dimensional atom probe tomography.Level-set computer simulations were carried with different setups of driving forces to explore their contribution to the microstructure development with and without solute drag.The results showed that the favorable growth advantage for some grains leading to a transient stage of abnormal grain growth is controlled by several drivers with varying importance at different stages of annealing.For longer annealing times,residual dislocation density gradients between large and smaller grains are no longer important,which leads to microstructure stability due to predominant solute drag.Local fluctuations in residual dislocation energy and solute concentration near grain boundaries cause different boundary segments to migrate at different rates,which affects the average growth rate of large grains and their evolved shape.

Research on in-situ condition preserved coring and testing systems

As shallow resources are increasingly depleted,the mechanics'theory and testing technology of deep insitu rock has become urgent.Traditional coring technologies obtain rock samples without retaining the in-situ environmental conditions,leading to distortion of the measured parameters.Herein,a coring and testing systems retaining in-situ geological conditions is presented:the coring system that obtains in-situ rock samples,and the transfer and testing system that stores and analyzes the rocks under a reconstructed environment.The ICP-Coring system mainly consists of the pressure controller,active insulated core reactor and insulation layer and sealing film.The ultimate bearing strength of 100 MPa for pressurepreservation,temperature control accuracy of 0.97%for temperature-retained are realized.CH_(4)and CO permeability of the optimized sealing film are as low as 3.85 and 0.33 ppm/min.The average tensile elongation of the film is 152.4%and the light transmittance is reduced to 0%.Additionally,the pressure and steady-state temperature accuracy for reconstructing the in-situ environment of transfer and storage system up to 1%and±0.2 is achieved.The error recorded of the noncontact sensor ring made of lowdensity polymer is less than 6%than that of the contact test.The system can provide technical support for the deep in-situ rock mechanics research,improving deep resource acquisition capabilities and further clarifying deep-earth processes.

Gas seepage equation of deep mined coal seams and its application

In order to obtain a gas seepage law of deep mined coal seams, according to the properties of coalbed methane seepage in in-situ stress and geothermal temperature fields, the gas seepage equation of deep mined coal seams with the Klinkenberg effect was obtained by confirming the coatbed methane permeability in in-situ stress and geothermal temperature fields. Aimed at the condition in which the coal seams have or do not have an outcrop and outlet on the ground, the application of the gas seepage equation of deep mined coal seams in in-situ stress and geothermal temperature fields on the gas pressure calculation of deep mined coal seams was investigated. The comparison between calculated and measured results indicates that the calculation method of gas pressure, based on the gas seepage equation of deep mined coal seams in in-situ stress and geothermal temperature fields can accu- rately be identical with the measured values and theoretically perfect the calculation method of gas pressure of deep mined coal seams.

Research progress and application of deep in-situ condition preserved coring and testing

With the depletion of shallow resources,the exploration of deep earth resources has become a global strategy.The study of the different patterns in the physical mechanical properties of rocks at different occurrence depths is the basis for exploring deep into the earth,with the core and premise being the acquisition and testing of deep in-situ core specimens.Based on the original idea of deep in-situ condition preserved coring(ICP-Coring)and testing,combined with theoretical modeling,numerical analysis,test platform development,indoor testing and engineering application,the principles and technologies of deep ICP-Coring are developed.This principle and technology consists of five parts:in-situ pressurepreserved coring(IPP-Coring),in-situ substance-preserved coring(ISP-Coring),in-situ temperaturepreserved coring(ITP-Coring),in-situ light-preserved coring(ILP-Coring),and in-situ moisturepreserved coring(IMP-Coring).The theory and technology of temperature and pressure reconstruction at different occurrence depths and in different environments are proposed,and prototype trial production was completed by following the principle of displacement and tests based on the in-situ reconstructed environment.The notable advances are as follows:(1)Deep in-situ coring system:A pressure-preserved controller with an ultimate bearing capacity greater than 140 MPa,highperformance(temperature-resistant,pressure-resistant,and low thermally conductive)temperaturepreserved materials,an active temperature control system,and high-barrier quality-preserved membrane materials were developed;a deep ICP-Coring capacity calibration platform was independently developed,a deep in-situ coring technology system was developed,and the acquisition of deep in-situ cores was realized.(2)In-situ storage displacement system:Following the dual-circuit hydraulic design idea,a single-drive source push-pull composite grabbing mechanism was designed;the design of the overall structure for the deep in-situ displacement storage system and ultrahigh pressure cabin structure was completed,which could realize docking the coring device and core displacement in the in-situ reconstructed environment.(3)Test analysis system:A noncontact acoustic-electric-magnetic test system was developed under the in-situ reconstructed environment,and the errors between the test results and traditional contact test results were mostly less than 10%;a detachable deep in-situ core true triaxial test system was developed,which could perform loading tests for deep in-situ cores.The relevant technological achievements were successfully applied to the exploration and development of deep resources,such as deep mines,deep-sea natural gas hydrates,and deep oil and gas.The research results provide technical and equipment support for the construction of a theoretical system for deep in-situ rock mechanics,the development of deep earth resources and energy,and the scientific exploration of different layers and occurrence depths(deep and ultradeep)of the Earth.

Mineralogy,microstructures and geomechanics of rock salt for underground gas storage

Rock salt has excellent properties for its use as underground leak‐proof containers for the storage of renewable energy.Salt solution mining has long been used for salt mining,and can now be employed in the construction of underground salt caverns for the storage of hydrogen gas.This paper presents a wide range of methods to study the mineralogy,geochemistry,microstructure and geomechanical characteristics of rock salt,which are important in the engineering of safe underground storage rock salt caverns.The mineralogical composition of rock salt varies and is linked to its depositional environment and diagenetic alterations.The microstructure in rock salt is related to cataclastic deformation,diffusive mass transfer and intracrystalline plastic deformation,which can then be associated with the macrostructural geomechanical behavior.Compared to other types of rock,rock salt exhibits creep at lower temperatures.This behavior can be divided into three phases based on the changes in strain with time.However,at very low effective confining pressure and high deviatoric stress,rock salt can exhibit dilatant behavior,where brittle deformation could compromise the safety of underground gas storage in rock salt caverns.The proposed review presents the impact of purity,geochemistry and water content of rock salt on its geomechanical behavior,and thus,on the safety of the caverns.

Treatment of mine water high in Fe and Mn by modified manganese sand

The iron and manganese absorption properties of several filter media were studied. Four plain filter media and six surface-modified media were examined. The surface modification was performed using potassium permanganate as a surface treatment. The surface-modified manganese sand was found to be most efficient at removing iron and manganese from water. The metal concentrations in filtered effluent were between 0.01 and 0.04 mg/L, which is far lower than the standard for recycle water. A concen-tration of 5% KMnO4 was found to be most effective as surface modifier. The surface of the manganese sand modified by 5% KMnO4 was examined and found to be covered with a dense membrane of some compound. The membrane had the advantages of uniform texture, large surface area and physical and chemical stability. It was effective at removing iron and manganese from mine water.

Development and Prospect of China Uranium Mining and Metallurgy

The development of industry of uranium mining and metallurgy in China has been reviewed generally,emphasizing on investigation approaches and application levels of uranium mining technologies such as in-situ leaching,heap leaching,stope leaching:on the basis of analysis on status of uranium mining and metallurgy and problems existed,also considering the specific features of deposit resources,the development orientation of uranium mining and metallurgy in China is pointed out.The industry of China uranium mining and metallurgy is faced to new opportunity of development and challenge in 21st century,the only way to realize sustainable development of uranium mining and metallurgy and harmonious development between economy and environment is to develop new technology on mining,ore beneficiation and metallurgy,increase the utilization level of uranium resources,low down impact on environment caused by mining and metallurgy.