| Suppression of coal and gas outburst is a difficult problem encountered in complicated coal seam mining. The content of the gas in the coal bed is the key factor to determine the emission quantity of a mine, and it is also one of the important indexes of gas emission danger. So the depth research on the existing state of gas, especially the content of the gas and the disposition of absorbed gas and dissociated gas in coal is very important to master the potential content and its function, which will be helpful to reveal the essence of the gas and coal extrusion phenomenon. However, so far, the researches on the temperature effect on the absorption of methane in coal have been focused on the condition above 30℃, the report regarding the condition below 0℃has not been released. Firstly, the WY-98A gas-measure-apparatus is improved in this paper, which enables the experiments in a low temperature. Then, many absorption experiments on coal samples from Yu Min, Tan Jia-chong, Yi Ping-dong and Li Ren in normal and low temperature have been done with this apparatus. Also introduces coal sample industry analysis method and low-temperature coal adsorbs methane process and freezing coal's uniaxial compressive strength experiment.By the comparison of the coal methane-absorption tests and studying the methane-absorption features, the conclusions have been obtained as follows:1. Comparing with the primary apparatus's experimental results, the experimental results of the improved WY-98A apparatus show the relability, meanwhile the primary apparatus is of expendability.2. With the reformed WY-98A adsorption constant determinator,the CH4 adsorption constants"a,b"of coal have been obtained at a low temperature (T≤0℃) for the first time. Through data fitting, when the temperature T is below zero degree centigrade, the sorption isotherm of CH4 in the coal still belongs to"â… "adsorption type. It can be used to characterize the CH4 adsorption model of coal at a low temperature with the Langmuir equation.3. In the low-temperature phase, the same coal sample at the same pressure, the adsorption capacity is negatively correlated with temperature. As the temperature decreases, coal methane adsorption capacity increases. The greater is the pressure, the more obvious trends are seen in the adsorption capacity of coal with adsorption temperature. The absorption increases linearly as the pressure increases at low pressure, then the absorption rate decreases. When the pressure reaches a certain degree, the absorption capacity reaches its saturation value, the absorption value will not be changed when the pressure gets higher, and the absorption is much more influenced by temperature than by pressure.4. In the low-temperature phase (T≤0℃), the value of Langmuir constant of coal is significantly higher than that at the room temperature phase (T= 30℃).5. The relationship between a(absorption value) and T(temperature) is established. The relationship between a and T makes it possible to measure the methane-absorption of the depth coal in advance. If the temperature at a certain depth and the grade of coal can be predicted, the a can be worked out with the appropriate equation.6. By the uniaxial compressive strength experiment with the moulded samples, when water is injected into and gets frozen, their deformation is divided into four stages, i.e. compaction stage, flexible segment stage, plastic yield stage and destruction stage. With the freezing temperature falls, the uniaxial compressive strength of the test ones increases significantly; the changes of Poisson's ratio is not obviously, but the whole trends tends to be increased.7. It is concluded that the reliability of using the exponential function as a tool to fit the experimental data based on the absorption is the highest, while that of using the power function is the lowest. This shows that using exponential function to describe the coal seam gas content is more accurate, with the help of computer simulation CBM extraction.
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