Papers by Keyword: Rock Salt

Abstract: The roadbed base of railway in Qarhan Salt Lake area entirely consists of brine saturated rock salt formations. However, low salinity brine would cause corrosion for roadbed and the stability of rock salt roadbed would be directly affected. In this paper, physical and mechanical properties of brine-dissolved rock salt have been tudied, as well as Computer Tomography was used to scan and analyze the meso-structural changes in rock salt before and after corrosion. The results show that density of rock salt would be changed obviously in the process of corrosion.The deriving or closing of meso-fissures in rock salt could been found with rock salt immigrating and corrosion damage.

Abstract: In order to determine the long-term mechanical properties of surrounding rock of salt cavern gas storage, long tri-axial creep test studies on rock salt of the field were carried out. Based on the test data, long-term strength of rock salt was determined, and comparatively analysis was conducted combined with of the instantaneous test. The study results show that: Considering the axial strain, radial strain and volumetric strain to determine the long-term strength of rock salt can ensure reliability of the results. Under the same condition, the less salt content, the value of long-term strength is higher. Tri-axial creep process has a different effect degree between cohesion and internal friction angle; it is more sensitive to cohesion. The strain limit should be considered for the stability analysis of multi-bedded salt cavern gas storage construction and pay more attention about the mechanical properties of the interlayer parts. The study results provide references for researching the surrounding rock long-term mechanical properties of salt cavern gas storage.

Abstract: In order to make a research on all the factors which influence the dissolution rate of the rock salt, this article study on how the temperature, concentration of the rock salt solution, the dissolution obliquity, and the velocity influence the rock salt dissolution rate. The experiment shows that, all the factors make strong influences on the dissolution rate as follow: ⑴ when the obliquity is 180°, the dissolution rate is the largest, and the 0°is the smallest. The dissolution rate increases with the increasing of the obliquity. ⑵ the dissolution rate increases with the concentration to the largest and then insoluble in saturation.⑶ the dissolution rate increases with the temperature increase. ⑷At first, the dissolution increases with the velocity of the flow, then decreases to stabilize.⑸ This article also integrates the relationship between the temperature, obliquity, velocity and the dissolution rate, and the research result will play a key role in the production of cavity and the numerical simulation in the production procedure.

Abstract: The chemical kinetics dissolution of rock salts from Sakon Nakhon Basin is characterized by drill cores and compared to geochemical compositions of natural brines obtained within the study areas in Udon Thani and Sakon Nakhon Province, Thailand. A criterion for rock salt core analysis depends upon the maximum amount of halite, based on X-ray diffractometry. Mass balance relation between brines and rock salt dissolution is conducted by the difference of initial and final weights of the core sample in each experimental batch. To monitor salinity related to its dissolution, the concentrations of total dissolved solids (TDS) are determined for each time period. The dissolution rate of rock salts can be evaluated from chemical compositions of the reactants; sodium-chloride (Na-Cl, halite) and calcium-sulphate (Ca-SO₄, anhydrite), corresponding to the TDS content, against the experimental variables of time and temperature. The most important aspect of brine and rock salt interfaces concerns the chemical kinetics developed for the rate of reaction (R) and rate constant (k) as R = k [NaC^0.7[CaSO₄]^0.8. The overall order of the reaction is experimentally 1.5 with respect to concentration of sodium chloride and calcium sulphate. Phase transitions based on the behavior of the thermodynamic free energy as a function of thermodynamic variables are accompanied by the release of heat. The activation energy needs for the dissolution reaction of rock salt is-18.08 kJ/mol. The experimental result indicates the exothermic reaction, similar to the calculation by theoretical thermodynamics. Saturation indexes of brines as a function of anhydrite reveal the supersaturating condition while rock salt dissolution reaches the equilibrium condition.

Abstract: In the present paper, the time-dependent behavior of a salt cavern was analyzed using finite element method. A viscoplastic model considering inelastic volume changes was utilized to describe the time-dependent mechanical behavior of rock salt. The model was then implemented in a finite element procedure to analyze the stress and deformation of rock salt around an underground cavern using an axisymmetric representation. Finally, finite element analyses results were compared with those obtained by a viscoplastic model neglecting inelastic volume changes.

Abstract: Huai’an salt mining industry exploitation is introduced in this paper. We analysis the problems and influence factors of geological environment, such as rock-salt cavity roof collapse, the pollution to environment, brine leak and based on huai’an geological structure and the current method of rock salt mining process. In the analysis, the reasons due to the problems is be shown in details. We put forward the corresponding suggestions and countermeasures of prevention and control according to these geological environment problems as the references for related engineering design, construction, operation and environmental protection of the local salt mining enterprise and Huaian bureau of land and resources,. and so on.

Abstract: Uniaxial compression creep tests have been performed on a kind of rock salt similar material and laminated salt rock similar material on the base of salt rock gas-storage in Jintan. The creep tests show that the rheological property of the similar material is basically the same with the original rock. Under the uniaxial compression, the deformation gradually approaches to be constant after the early short stage of creep attenuation. The similar material shows stress-dependent behavior obviously under different stress stage, the greater the load the higher the creep ratio and creep deformation. A creep constitutive equation which is suitable to rock salt is used to the similar material, and it fits with the obtained creep data very well. The results show that the similar material developed in this passage has the same creep property as the original salt rock,and this material can be used to simulated the deformation and failure of underground gas storage constructed in bedded salt deposits.

Abstract: Through a lot of rock salt dissolving characteristics tests without stress effect, rock salt dissolving model without stress effect has been studied. The variation of shape of rock salt solid surface has been controlled by rock salt dissolving process directly, and rock salt dissolving model without stress effect can be built by the process of exchange of materials in dissolved boundary layer; through rock salt dissolving characteristics test without stress effect under different concentration, the computing equation by dissolved mass per unit area and concentration and dissolving time has been obtained; depended on the result of test and rock salt dissolving model without stress effect, the value of diffusion coefficient of rock salt has been computed. The achieved results on this paper can provide a foundation for the further analyses of rock salt dissolving characteristics with stress effect.

Abstract: Various factors were investigated to decide the mechanical properties of (Mn1–xNix)3O4 ceramics, that are typical composition systems of NTC (negative temperature coefficient) thermistors. The strength of NTC thermistor ceramics can be improved by designing the material so that the compressive stress may remain at the surface of the ceramics. At high temperature, the thermal expansion coefficient of a rock salt phase segregated internally ceramic increases over that of the spinel phase, further, on the surface of the ceramics, this compressive stress remains below room temperature. Moreover, it was confirmed that the stress analysis result by the FEM corresponded well with the stress measurement result on the surface of the ceramics measured by μ -XRD.