ABSTRACT
In order to deeply study the basic characteristics, diffusion laws, and flow laws of coal gangue and coal gangue slurry, the basic characteristic parameters of coal gangue and coal gangue slurry were obtained through particle size distribution test, electron microscope scanning test, X-ray diffraction test, X-ray fluorescence spectrum test, and angle of repose test. The conveying performance test of coal gangue slurry was carried out, and based on this, a simulation test of coal gangue slurry caving areas was designed. The diffusion and flow laws of coal gangue slurry under the same inclination angle were summarized, and the field test of fluidization filling in the caving areas was conducted. The results show that: (1) The water-to-gangue ratio was the main controlling factor for the conveying performance of coal gangue slurry. The extensibility, slump, and bleeding rate of the coal gangue slurry increased with the increase of the water-to-gangue ratio. (2) The diffusion profile of coal gangue slurry at different dip angles was arc-shaped, and the diffusion distance of slurry increased with the increase of infiltration time. However, there were differences in the sustained diffusion ability of different dip angles. (3) At the same time interval, the spatial accumulation patterns of scattered gangue in different regions will lead to differences in the diffusion speed of the slurry. (4) Both burying and hanging pipes in the falling area can safely and efficiently fill the gangue slurry. The diffusion distance of the caving areas in the test working face was basically consistent with the diffusion distance of the slurry in the simulation test of the coal gangue slurry caving areas.
ABSTRACT
Coal seam deformation due to gas adsorption affects the stability of the underground structure. Natural coal blocks of the Shanxi Formation were selected to study the dynamic adsorption characteristics of coal samples subjected to CO2, CH4, and N2 gas injections under coaxial pressure and confining pressure (7 MPa), as well as the displacement of CH4 with CO2 and N2 under the same conditions. The results show that, under the same conditions, the strain in the coal samples first increased, followed by a rapid increase along with the increase in pressure, with the transverse strain being always higher than the axial strain. The amount of gas adsorption varied from high to low as CO2 > CH4 > N2, and the final adsorption strains and equilibrium times were different for each gas. Based on the increase in gas pressure, the gas adsorption strain curve can be divided into two stages. The displacement of N2 only uses partial pressure to achieve the desorption of CH4 in the coal sample, leading to shrinkage deformation of the coal sample. In contrast, the displacement of CO2 has the dual effects of competitive adsorption and partial pressure reduction on CH4, leading to the swelling deformation of the coal sample.
ABSTRACT
Under the new vista of carbon neutrality, all industries in China face new challenges. As the pillar industry for fossil energy, the coal industry cannot blindly "de-coal". It is necessary to combine the two-way force associated with abandoned mines to turn energy into resources and problems into solutions. Innovation that combines emission reduction and neutralization can overcome the bottlenecks in carbon neutralization in abandoned mines, and help achieve the national carbon peak in 2030 and carbon neutrality in 2060. This involves the entire life cycle of the mine, including the status quo of abandoned coal mines, and the development of downstream industries. The development mode of resource utilization in abandoned mines in accordance with the national situation was summarized, and the suggestion of carbon neutralization in abandoned mines was put forward, which involves three steps: (1) Define the value of abandoned mines, consolidate energy market share, enjoy the policy dividend, and realize carbon neutralization breakthrough; (2) list the development path of carbon neutralization in abandoned mines, utilize photosynthesis to sequester carbon, combine industrial advantages to promote the development of a new energy industry, promote the integration of carbon emission, gathering, sequestration and utilization, realize carbon sequestration and mineralization in terminals and participate in carbon sink market allocation; (3) promote multiple simultaneous measures to solve existing problems, develop abandoned mines, and implement carbon neutralization goals.
