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Modelling of the relationship between trace elements and three species of sulfur in coal
Based on the determination of several trace elements in coal particulate of different specific gravity, three-variables regression equations relate the contents of trace elements Be, Cd,Co, Pb, Cu, Ni, As and three species of sulfur in coal were well established. For elements Cd, Co, Pb, Cu and Ni, the regression equations were successfully used for prediction of these trace elements in individual part of coal with different specificgravity. Factor analysis was also used to analyze the data sets.The results showed that a three factor model can interpret the datasets reasonably. Trace elements Cd, Co, Pb, Cu, Ni, inorganic sulfide and total sulfur in coal are high correlated with the first factor. Trace elements Be, sulfate and organic sulfide are high correlated with the second factor and trace elements Cr and As are high correlated with the third factor. The factors can be interpreted by the chemical properties of these elements....
2020-06-12 16:16:51浏览：1429
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A method of determining the permeability coefficient of coal seam based on the permeability of loade
This study developed the equipment for thermo-fluid-solid coupling of methane-containing coal, and investigated the seepage character of loaded coal under different working conditions. Regarding the effective pressure as a variable, the variation characteristics of the gas permeability of loaded meth-ane-containing coal has been studied under the conditions of different confining pressures and pore pres-sures. The qualitative and quantitative relationship between effective stress and permeability of loaded methane-containing coal has been established, considering the adsorption of deformation, amount of pore gas compression and temperature variation. The results show that the permeability of coal samples decreases along with the increasing effective stress. Based on the Darcy law, the correlation equation between the effective stress and permeability coefficient of coal seam has been established by combining the permeability coefficient of loaded coal and effective stress. On the basis of experimental data, this equation is used for calculation, and the results are in accordance with the measured gas permeability coefficient of coal seam. In conclusion, this method can be accurate and convenient to determine the gas permeability coefficient of coal seam, and provide evidence for forecasting that of the deep coal seam....
2020-06-12 16:16:50浏览：1441
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Energy Saving and Pollution Reducing Effects of Coal Combustion Catalysts
Coal catalytic agents (CCS type) have been prepared to improve coal combustion and reduce air pollution.The energy and pollution reductions resulting from the catalysts have been examined with thermal analysis and chromatography.The CCS agents lower the ignition temperature by 30-80℃ and improve the coal combustion efficiency by 10%-25%.The agents also reduce the release of carbon monoxide,sulfur dioxide,and coal particles to environment.The working mechanisms of the catalysts are discussed in terms of their participation in various physico-chemical processes during combustion....
2020-06-12 16:16:50浏览：1434
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Chromium leaching mechanism of coal mine water——a modeling study based on Xuzhou-Datun coal mine dis
In order to investigate chromium contamination of coal mine water, to analyze chromium leaching mechanism and to evaluate environment pollution potential of coal mine water, we perform site investigations, physical and computer modeling in the Xuzhou-Datun coal mine district. The result of our test samples shows that chromium concentration was 9 μg/L in roof leachate and 3 μg/L in coal leachate. The host rock has a higher pollution potential than that of coal seams. Leaching experiments and XRD test results indicate that chromium is released from the process of transforming illite to kaolinite. The pH, pe and temperature of coal mine water affect the chromium leaching behavior. Modeling results suggest that the adsorption of adsorbents controls chromium concentration in coal mine water. The chromium adsorption ratio is quite low in both an acid and in an alkaline environment. Therefore, coal mine water has a high pollution potential. Under other conditions, chromium adsorption is stronger in a neutral water environment, so that chromium concentrations may be very low....
2020-06-12 16:16:49浏览：1436
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Fractal classification and natural classification of coal pore structure based on migration of coal
According to the data of 146 coal samples measured by mercury penetration, coal pores are classified into two levels of ＜65 nm diffusion pore and ＞65 nm seeping pore by fractal method based on the characteristics of diffusion, seepage of coal bed methane(CBM) and on the research results of specific pore volume and pore structure. The diffusion pores are further divided into three categories: ＜8 nm micropore, 8-20 nm transitional pore, and 20-65 nm minipore based on the relationship between increment of specific surface area and diameter of pores, while seepage pores are further divided into three categories: 65-325 nm mesopore,325-1000 nm transitional pore, and ＞1000 nm macropore based on the abrupt change in the increment of specific pore volume....
2020-06-12 16:16:48浏览：1422
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Fracture mechanics model of fully mechanized top coal caving of shallow coal seams and its applicati
Based on break characteristics of roofs in fully mechanized top-coal mining of thick shallow coal seams, a fracture mechanics model was built, and the criterion of crack propagation in the main roof was derived using the fracture mechanics theory. The relationships between the fracture length of the roof and the working resistance of the supports were discovered, and the correlations between the load on the over-lying strata and the ratio of the crack’s length to the thickness of the roof were obtained. Using a working face of Jindi Coal Mine, Xing county Shanxi province as an example, the relationships between the frac-ture length of the roof and the working resistance of the supports were analysed in detail. The results give a design basis in hydraulic top coal caving supports, which could provide useful references in the prac-tical application. On-site experiment proves that the periodic weighting step interval of the caving face is 15-16 m, which is basically consistent with the theoretical analysis results, and indicates that the mechanized caving hydraulic support is capable of meeting the support requirements in the mining of a super-thick but shallowly buried coal seam....
2020-06-12 16:16:48浏览：1424
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Vegetation Growth Monitoring Under Coal Exploitation Stress by Remote Sensing in the Bulianta Coal M
Coal exploitation inevitably damages the natural ecological environment through large scale underground exploitation which exhausts the surrounding areas and is the cause of surface subsidence and cracks.These types of damage seriously lower the underground water table.Deterioration of the environment has certainly an impact on and limits growth of vegetation, which is a very important indicator of a healthy ecological system.Dynamically monitoring vegetation growth under coal exploitation stress by remote sensing technology provides advantages such as large scale coverage, high accuracy and abundant information.A scatter plot was built by a TM (Thematic Mapper) infrared and red bands.A detailed analysis of the distributional characteristics of vegetation pixels has been carried out.Results show that vegetation pixels are affected by soil background pixels, while the distribution of soil pixels presents a linear pattern.Soil line equations were obtained mainly by linear regression.A new band, reflecting vegetation growth, has been obtained based on the elimination of the soil background.A grading of vegetation images was extracted by means of a density slice method.Our analysis indicates that before the exploitation of the Bulianta coal mining area, vegetation growth had gradually reduced; especially intermediate growth vegetation had been transformed into low vegetation.It may have been caused by the deterioration of the brittle environment in the western part of the mining area.All the same, after the start of coal production, vegetation growth has gradually improved, probably due to large scale aerial seeding.Remote sensing interpretation results proved to be consistent with the actual situation on the ground.From our research results we can not conclude that coal exploitation stress has no impact on the growth of vegetation.More detailed research on vegetation growth needs to be analyzed....
2020-06-12 16:16:47浏览：1442
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A New Understanding on South China Permian Coal-bearing Strata and Coal Accumulation Regularity
The Longtan Formation was originally thought to belong to the Late Permian, but this study reveals that the lower part of this formation belongs to the Middle Permian. The study proposes the corresponding chronostratigraphic boundary and new schemes for the correlation of geological sections. Based on these schemes a new understanding on the accumulation regularity of Permian coal measures in South China is reached....
2020-06-12 16:16:47浏览：1441
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Combined Removal of Surface Moisture and Dust from Feed Coal for Coal Dry Cleaning with an Air-solid
A demonstration plant and a commercial plant employing coal dry cleaning technology with an air-solid fluidized bed were built in China. The operation practice of these two plants shows that the surface moisture and the fines or dust of feed coal must be well controlled as low as possible. For this purpose, a new process of combined removal of surface moisture and dust from feed coal using a vibrated fluidized bed dryer was investigated in a batch test apparatus and a pilot test system. A mathematical model on drying kinetics of coal surface moisture was developed and three empirical formulas of the model coefficient involving the main operating variables were determined based on the test results from the batch test apparatus. The mathematical model shows that the surface moisture retained in coal during drying decreases exponentially with drying time. According to this model, a new divisional heat supply mode, in which the inlet gas of higher temperature was introduced into the fore part of the dryer and the inlet gas of lower temperature into the rear part of the dryer, was employed in the pilot test system. The pilot tests show that 1) the new divisional heat supply mode is effective for lowering down the average temperature and reducing the total heat loss of the outlet gas off the dryer, 2) the moist coal of about 60 g/kg surface moisture contentcan be dried to about 10 g/kg, and simultaneously the fines (...
2020-06-12 16:16:45浏览：1427
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Top coal flows in an excavation disturbed zone of high section top coal caving of an extremely steep
Compared with gentle dip long-wall caving, the length of a working face in fully-mechanized top-coal caving for extremely steep and thick seams is short, while its horizontal section is high with increasing production. But the caving ratio is low, which might result in some disasters, such as roof falls, induced by local and large area collapse of the top coal in a working face and dangers induced by gas accumulation. After the development of cracks and weakening of the coal body, the tall, broken section of the top coal (a granular medium) of an extremely steep seam (over 60°) shows clear characteristics of nonlinear movement, We have thoroughly analyzed the geological environment and mining conditions of an excavation disturbed zone. Based on the results from a physical experiment of large-scale 3D modeling and coupling simulation of top coal-water-gas, we conclude that the weakened top coal can be regarded as a non-continuous medium. We used a particle flow code program to compare and analyze migration processes and the movements of a 30 m high section top coal over time before and after weakening of an extremely steep seam in the Weihuliang coal mine. The results of our simulation,experiment and monitoring show that pre-injection of water and pre-splitting blasting improve caving ability and symmetrical caving, relieve space for large area dynamic collapse of top coal, prolong migration time of noxious gases and release them from the mined out area and so achieve safety in mining....
2020-06-12 16:16:44浏览：1405
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Tectonically deformed coal types and pore structures in Puhe and Shanchahe coal mines in western Gui
To evaluate the effect of tectonic deformation on coal reservoir properties,we provide an analysis of the types of tectonically deformed coal,macro- and microscopic deformation and discuss pore structural characteristics and connectivity based on samples from the Puhe and Shanchahe coal mines.Our research shows that the tectonically deformed coal mostly includes cataclastic structural coal.mortar structural coal and schistose structural coal of a brittle deformation series.The major pore structures of different types of tectonically deformed coal are transitional pores and micropores.The pore volumes of macropores and visible fracture pores produced by structural deformations vary over a large range and increase with the intensity of tectonic deformation.Mesopores as connecting passages develop well in schistose structural coal.According to the shapes of intrusive mercury curves,tectonically deformed coal can be divided into parallel,open and occluded types.The parallel type has poor connectivity and is relatively closed; the open type reflects uniformly developed open pores with good connectivity while the occluded type is good for coalbed methane enrichment,but has poor connectivity between pores....
2020-06-12 16:16:43浏览：1407
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Research into comprehensive gas extraction technology of single coal seams with low permeability in
For a low permeability single coal seam prone to gas outbursts,pre-drainage of gas is difficult and inefficient,seriously restricting the safety and efficiency of production.Radical measures of increasing gas extraction efficiency are pressure relief and infrared antireflection.We have analyzed the effect of mining conditions and the regularity of mine pressure distribution in front of the working face of a major coal mine of the Jiaozuo Industrial (Group) Co.as our test area,studied the width of the depressurization zone in slice mining and analyzed gas efficiency and fast drainage in the advanced stress relaxation zone.On that basis,we further investigated and practiced the exploitation technology of shallow drilling,fan drilling and grid shape drilling at the working face.Practice and our results show that the stress relaxation zone is the ideal region for quick and efficient extraction of gas.By means of an integrated extraction technology,the amount of gas emitted into the zone was greatly reduced,while the risk of dangerous outbursts of coal and gas was lowered markedly.This exploration provides a new way to control for gas in working faces of coal mines with low permeability and risk of gas outbursts of single coal seams in the Jiaozuo mining area....
2020-06-12 16:16:42浏览：1433
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Rare earth element geochemistry of groundwaters from coal bearing aquifer in Renlou coal mine, north
Rare earth element (REE) concentrations of two different types of groundwaters (high SO42- water-SW and high alkaline waterCW) from coal bearing aquifer (-400～-280 m) in Renlou coal mine, northern Anhui Province, China were measured. The results indicated that they had different REE characteristics: the total concentrations of REEs (∑REE) of SW were lower than those of CW in general although they all had heavy REEs enriched relative to light REEs. The dissolved REE inorganic species of SW included Ln3+, LnCO3+, LnSO4+,Ln(CO3)2- and Ln(SO4)2-, whereas the CW are Ln(CO3)2- and LnCO3+ dominant, and the proportions of Ln(CO3)2- increased while other species decreased with pH increasing. Combined with correlation analysis, the enrichment and fractionation of SW (low alkaline water) were considered to be affected by alkaline concentrations via affecting the types and proportons of REE inorganic species. However, the effect of alkaline concentrations to the enrichment and fractionation of REEs of CW (high alkaline water) was less important than total dissolved solids and pH, which reflected the contribution from different rocks they flowed over, different degrees of water-rock interactions and/or REE solid-liquid partition coefficients....
2020-06-12 16:16:42浏览：1432
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Performance of PAHs emission from bituminous coal combustion
Carcinogenic and mutagenic polycyclic aromatic hydrocarbons (PAHs) generated in coal combustion have caused great environmental health concern. Seventeen PAHs (16 high priority PAHs recommended by USEPA plus Benzo[e]pyrene) present in five raw bituminous coals and released during bituminous coal combustion were studied. The effects of combustion temperature, gas atmosphere, and chlorine content of raw coal on PAHs formation were investigated. Two additives (copper and cupric oxide) were added when the coal was burned. The results indicated that significant quantities of PAHs were produced from incomplete combustion of coal pyrolysis products at high temperature, and that temperature is an important causative factor of PAHs formation. PAHs concentrations decrease with the increase of chlorine content in oxygen or in nitrogen atmosphere. Copper and cupric oxide additives can promote PAHs formation (especially the multi-ring PAHs) during coal combustion....
2020-06-12 16:16:40浏览：1421
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Fractal analysis of thermal conduction of loose coal
For deep mining engineering,heat transfer of coal mass is a vital factor in the thermal environment of coal mines.In order to study the thermal conduction mechanism,we obtained gray images of coal mass microstructure by scanning samples with a digital microscope.With the use of Matlab,these gray images were transformed into binary images,which were then transformed into a corresponding matrix consisting only of the values 0 and 1.According to the calculation method of box-counting dimension,we calculated the fractal dimension of the loose coal to be approximately 1.86.The thermal conductivity expressions of loose coal were derived based on the simulation method of thermal resistance.We calculated the thermal conductivity of loose coal by using a fractal model and compared the calculated values with our experimental data.The results show that the test data show an encouraging agreement with the calculated values.Hence fractal theory is a feasible method for studying thermal conductivity of loose coal....
2020-06-12 16:16:40浏览：1426
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