Search

To study the effects of organic micromolecules in coal on methane adsorption characteristics, organic micromolecules were extracted by n-hexane using microwave assisted method from coal samples to obtain the residual coal samples at 50°C, and atmospheric pressure. And their extracts were analyzed via the Gas Chromatography/Mass Spectrometry (GC/MS). And on this basis, the diesel was chosen to be as models for n-hexane extracts of coals and was used to add to coals. Methane sorption isotherms on raw coals, their residues and coals added diesel were tested. The results show that; At low pressure, the difference of gas adsorption between raw coals and their residues is insignificant, while as the pressure increases, the amount of coal methane adsorption is gradually higher than its residues; Different from raw coal and their residues, at greater pressure, gas absorption increment for coal added diesel is more higher under the same pressure section, and as the pressure increases, the final amount of methane adsorb slightly higher than raw coals. For all coal samples examine, experimental date are fit by the Langmuir and Langmuir-Henry dual-model, which suggests that methane sorption by the coal samples can be explained by adsorption on the surface that occurred at low pressures described by a Langmuir isotherm and at high pressures, penetration (dissolution) into the bulk described by Henry's law, and organic micromolecules in coal are help for increasing the amount of coal methane adsorption at high pressures. [ABSTRACT FROM AUTHOR]

Based on the coal samples of the outburst coal seam No. 8 of Qingdong Mine in Huaibei, with the distribution characteristics of ground stress and gas pressure in stress-relief boundary area, the experiment of outburst coal's radial gas seepage was carried out under variable axial pressure, gas pressure and hole diameter by a self-developed test system of radial gas seepage. The experimental results show that the gas seepage flow increases with the increase of gas pressure under fixed axial pressure, and the relationship between gas seepage velocity and gas pressure can be described as quadratic polynomial function, the permeability of coal samples decreases rapidly with the increase of gas pressure in the range of 0-0. 6 MPa, then decreases slowly with the developing of gas pressure and tends to be stable; the permeability of coal samples decreases linearly with the increase of axial pressure under fixed gas pressure; Affected by the borehole pressure relief, the permeability of soft and low strength coal samples with large diameter borehole is significantly higher than the coal samples with small diameter borehole in low axial pressure stage, both permeability gradually tends to be the same with the increase axial pressure. [ABSTRACT FROM AUTHOR]

When the vehicle travels underground mine, its motion region is restricted to the roadways. So we can set the modification points which has been measured the coordinates in advance in roadways to correct the error state in INS/ Odometer integrated navigation. This method is aimed at increasing the navigation precision. Firstly, the computation method of position and velocity in Odometer was introduced. System dynamic model and observation model of INS/Odometer integrated navigation was built. Based on this, position modification filter equation of known point was constructed. After introducing the Parallel-Kalman filter to realize the dual filter of integrated navigation, INS/Odometer integrated navigation system based on position modification for underground mine vehicle was proposed. Experiment of simulated data and actual measurement were made to compare the navigation accuracy between before and after position modification. The results of the experiment indicate that the INS/Odometer integrated navigation performance is increased substantially by position modification of known points in roadways. Plane precision of real-time navigation increased from dozens of meters to meter scale, which is able to meet the needs of navigation for underground mine vehicle. [ABSTRACT FROM AUTHOR]

In order to reveal the soluble organic matter effect on the spontaneous combustion of coal, the infrared spectroscopy and GC/MS experiments were used to test the changes of coal surface microstructure and product ingredients after extracted by tetrahydrofuran. Based on the results of soluble organic matter affect the pore structure of the coal, and according to the gas-product release law of low temperature oxidation of coal before and after the extraction, effect of soluble organic matter of the coal on surfactant structure and low temperature characters of coal oxidation was discussed. The results indicate that after extraction, the content of hydroxyl and carboxyl in residual coal is reduced. Meantime, mineral content and active side chains and functional groups which involve high-content oxygen in coal also reduce. Coal soluble organic matter contains a large amount of the active groups, such as methyl, hydroxyl, carbonyl and ether etc. The total pore volume and surface area of the residual coal is increased in varying degrees. The average pore size of residual coal reduces from 6. 3 nm to 4. 9 nm. The oxygen consumption of extracted residual coal in low-temperature oxidation stage is significantly lower than that of raw coal, and CO, CO2, C2H4 and C2H6 gas emission reduced than raw coal to some extend. The soluble organic matter in coal promotes the spontaneous combustion of coal. [ABSTRACT FROM AUTHOR]

According to the coal spontaneous combustion theory and chemical structure of coal, the anisole and benzyl alcohol were adopted as the model compound. Authors researched the oxidation of methoxy and hydroxymethyl in model compounds from 20 °C to 130 °C. Oxidation products of model compound were measured at different temperatures by programmed heating. Oxidation properties of the model compound at different temperatures were analyzed by chromatographic. The results show that the oxidations of anisole and benzyl alcohol generate carbon monoxide, carbon dioxide, benzene and phenol. The oxidation activity of methoxy is weak before 50 °C and then gradually goes up with temperature increased, but the rate increase slowly. In contrast, the oxidation activity of hydroxymethyl in benzyl alcohol is weak before 70 °C. However, the oxidation activity of active group in benzyl alcohol increases once the temperature climbes to 70 °C. Especially, when the temperature reaches 120 °C, the oxidation activity of hydroxymethyl in benzyl alcohol dramatically grows. [ABSTRACT FROM AUTHOR]

In order to research the effect of soluble organic matter in coal on characteristics of gas sorption and desorption, the organic matters in coal seam 8 (Qingdong), coal seam 3 (Xutuan) and coal seam 8 (Suntuan) of Huaibei mining area were extracted by THF at nomal temperature and pressure. The gas adsorption capacity, vacuum desorption volume at normal pressure and variation of Ap of raw coal and residual coal were comparatively analyzed. After extraction, the Ap and gas adsorption capacity of coal seam 8 ( Qingdong) and coal seam 3 (Xutuan) are reduced. Meanwhile, the increment for gas adsorption capacity of those coal seams increases first and then decreases with the growing of gas pressure. In contrast,the gas adsorption capacity of coal seam 8(Suntuan) has not significant change. However, Ap of coal seam 8 (Suntuan) increases. The vacuum desorption volume at normal pressure of all there coal samples is increased. The gas dissolutes in soluble organic matter of coal and forms solid solutions in outburst coal seams, which lead to the increase of coal seam gas content,gas emission speed and coal seams outburst risk. Soluble organic matter occupies part of the pores in non-outburst coal seam, which can slow down the gas release and reduce the gas release rate. [ABSTRACT FROM AUTHOR]

To further study the correlation between fractal theory and coal particle size gradation, the different size of coal particle size distribution from the Coal Slurry Plant of the Zhangjiamao Mining was researched by fractal theory. The median diameter of pulverized coal to the particle size distribution curves could be identified by using laser particle size analyzer. By fitting curve linear of ln yv(r)--ln r, the fractal characteristics are showed, and the fractal dimension is lower than 2.3. For the Alfred and Rosin-Rammler model, the fractal dimension is both above 2.5. The median particle diameter of 6 µm samples of pulverized coal were mixed with the median diameter of 29 µm and 90 p, the results are both above 2.5, higher than the pulverized coal without PSD. Therefore, the fractal dimension is characteristic parameters for the PSD processing. The process of PSD improves the fractal dimension of pulverized coal. By measuring the fractal dimension, the particle size distribution of pulverized coal can be judged good or bad-graded, and whether close to the theoretical model or not. [ABSTRACT FROM AUTHOR]

The traditional method treats gyro-side as strong side in underground control network, which has proved to be not sustainable. Moreover, there is no appropriate way to compute whole network when gyro-sides are added. A new rigorous adjustment in one cast model was proposed to resolve the problem. The theoretical derivation of the new model was given and the theoretical advantage of the model was approved. At the same time, the gyro-side observations were attempted to put into the new model, and a self-adaptive weighting algorithm based on configuration structure was proposed, which optimized the model and improved the accuracy of traverse points. The case study of an underground first control network demonstrates that the proposed new model can effectively restrain the swing phenomenon caused by angle error propagation. The self-adaptive weighting algorithm can effectively correct traverse network warping caused by the joint of gyro-sides, therefore, the traverse network structure has been effectively enhanced and the point accuracy has been improved. [ABSTRACT FROM AUTHOR]