Observing the whole unloading process, the unloading time is 133 s when the density of coal bulk is 1600 kg/m 3, the unloading time is s when the density is 1350 kg/m 3 and the unloading time is s when the density is 1100 kg/m 3, so the higher the particle density in the silo, the faster is the unloading speed.
Both coal companies and Railways have envisaged to jointly ensure per day coal loading of 415 rakes of domestic coal and 30 rakes of imported coal to the power sector. 'In the current month ...
Conventional and cyclic unloading tests with different unloading rates were conducted to study the influences of unloading patterns and rates on the deformation characteristics and mechanical properties of tectonic coal. The results demonstrate that, under continuous unloading, a lower unloading rate promotes an increase in the circumferential strain but inhibits increases in axial strain.
In this study, coal fly ash was functionalized, using a simple onestep process (loading with Al3+ and sulfonation), to yield a solid acid catalyst (S/AlCFA) with strong acid sites. The catalyst was then used to produce furfural from xylose in a biphasic system (H2O(NaCl)/tetrahydrofuran). The furfural yield reached 82% at 180 °C60 min with catalyst/xylose ratio of : (w/w). With the ...
As the coal body has a hysteresis effect during the unloading process, it cannot be unloaded to 0 when unloading, and the minimum unloading level was set for the four kinds of samples; that is, after unloading to 2% σ c, the loading was performed until the sample was destabilized.
The loadingunloading process is represented as follows: 0 ... In cyclic loading process, the coal samples first exhibit the appearance of microcracks at the beginning stage. With the increase in the axial stress, the damage gradually accumulates and produces irreversible plastic deformation. When the peak load is reached, partial area of ...
Cyclic Loading and Unloading Process. Based on the results of AE filtering experimental results, the loading process for the ultrasonic test experiments carried out in this study is as follows: measure the ultrasonic wave parameters before the process of loading, load up to kN and maintain the force for 34 minutes; load up to kN and maintain the force for 34 minutes; unload up ...
Coalburst is a violent dynamic failure of coal during underground mining. It is of significance to study failure pattern as well as energy evolution and transition during coalbursts and how they are influenced by preconfinement. This paper presents unloadinginduced coalburst simulations using the distinct element method via a combined staticdynamic loadingunloading strategy.
Permeability changes with confining stress loadingunloading: (a) is the PUC; (b) is the cataclastic coal; (c) is the mylonitic coal; (d) is the loadingunloading process of confining stress. The increase in confining pressure compressed the coal matrix and internal fissures of the coal cores, and their permeability rapidly and then slowly ...
In the process of coal formation, the internal structure is different from the occurrence of primary cracks. As a result, the new crack generation and primary crack development of different samples are affected to different degrees during loading and unloading. Energy characteristics under true triaxial loading and unloading
Given the roadway deformation and surrounding rock control in the process of thin coal seam mining, the coalrock combination with inclination angles for 0°, 15°, 30°, 45°, and 60° was designed. The rock mechanic test machine was used to conduct a uniaxial compression test and a graded loading and unloading test on the coalrock combination; the failure characteristics of the two were ...
During the deformation process of coal under the combined highstatic confining pressure and axial disturbance loads, we found that the final instability failure of coal specimens, subjected to disturbance load, were more likely to occur in the disturbance loading and unloading stage, such as specimen SB1, and SD1.
Coal is an important, widelyused source of energy and a chemical raw material, which is transported globally in large quantities; more than a billion tonnes of coal per year are transported by sea (IEA International Energy Agency, 2020). However, its carriage as a cargo is associated with a number of hazards and coal must be carried in ...
To study the anisotropic mechanical properties and energy evolution of layered rock masses under the action of cyclic loading, uniaxial graded cyclic loading and unloading tests under different upper and lower stress limits were carried out on samples with different bedding angles (0°, °, 45°, °, and 90°) to explore the deformation and mechanical response characteristics of bedded ...
The coils are then loaded either on a reel style or cradle style uncoiling system. Cradle style uncoilers are relatively easy to load, you basically lower your coil onto the cradle, position the sides guides to center the coil and your coil is ready to be released. On a reel type the process is not as easy. You have a large heavy object either ...
The process of rock cycle loading and unloading results in the external force constantly performing work on the specimen. The external force is converted into elastic strain and dissipation energy. Using the principles of thermodynamics, energy transformation is the essential process by which the energy state of the specimen changes, as ...
A semicontinuous process system consisting of a singlebucket excavator, truck, crushing station, and belt conveyor is the main coal mining process system of a largescale hard coal openpit mine. Through analyzing the coal mining production process, the key issues of coal mining truck flow optimization are obtained. Statistical method of using triangular fuzzy numbers analyzes the key time ...
In the process of coal seam mining, the coal is disturbed by periodic pressure. This disturbance can be simplified to the loading process under different stress environments [5], [9], [10], [45], and the characteristics of the mining stress path are different under different advancing speeds [46]. Fig. 3 shows the loading path of the sample. M ...
In the true triaxial cyclic mechanical experiment of coal, most of the total work done by the three principal stresses is accumulated in the coal with elastic potential energy (the elastic strain energy will be released in the unloading process of external force, approximately equal to the negative work done by the external force in the ...
In the course of the experiment, the stress, strain and permeability of raw coal under loading and unloading conditions were recorded, and the specific experimental process was as follows: (1) First, the raw coal sample is scanned by CT apparatus, and then the sample coated with silica gel is installed in the pressure chamber. (2)
During the cyclic loading and unloading process, assuming that there was no energy exchange between the machine and the external environment, the test equipment transferred energy to the sample through mechanical work, part of which was converted into elastic energy stored inside the coal body, and could be completely released during unloading ...
Pollutants for Coal Storage, Loading, and Unloading in Ports A Case Study of Wharf in Tianjin Analysis of Dusting Links in Coal Storage, Loading, and Unloading The eld survey and literature review indicate main pollutants come from dust generated by agitation, dropping, or strong wind in the process of coal loading and unloading,
As a result, the crack of saturated coal samples cannot keep stationary in the initial stage of loading and unloading and it slips throughout the loading and unloading process. A large number of macrotensile cracks appeared in the failed coal samples with pore water, as the pore pressure provides tensile force to the cracks and promotes the ...
To further validate and promote the proposed damage constitutive model, the loadingunloading process of coal material is also simulated. Because energy is continuously transformed during loading, in the loadingunloading process, the damage variable is also defined by energy dissipation.
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