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Geochemistry of Permian Coal and Its Combustion Residues in Huainan Coalfield, China
INAA (instrumental neutron activation analysis) was used to determine the contents of trace elements in coal samples from 11 workable Permian coal seams in Huainan coalfield. With XRFS (X-ray fluorescence spectrometry), the geochemical composition of its combustion residues from Tianjiaan Power Plant and Luohe Power Plant was analyzed. In addition, the electron microprobe was employed to study the chemical composition of some fly ashes and bottom ashes. Compared with those of the coals around the world, most trace elements of the Huainan coal are characterized by a normal abundance.Like most coals worldwide, the elements Se, S, As, Sb, Br, U and Cl are enriched in Huainan coal according to Clarks value, while the other elements tend to be diluted. The large fluctuation in the contents of trace elements in this kind of coal demonstrates great differences in coal seams. On the other hand, the contents of these elements are very similar in different bottom and fly ash samples. The elements with low organic affinity tend to concentrate in fly and bottom ash than in coal, especially those elements associated with Fe. However, the elements with strong organic affinity tend to be volatile during the combustion. Moreover, the abundance of the elements in fly ash and bottom ash changes with different densities and with different particle sizes. The bottom and fly ashes consist of glass, lime,mullite, coal residues and ferrite minerals. Some residual chars contain higher contents of volatile elements, such as S, P, Cl and As, indicating that the ash containing more residual chars has a strong adsorption of some hazardous elements, suggesting a possible utilization of power plant ash in the field of water cleaning....
2020-06-12 16:17:21浏览：1428
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Microseismic Monitoring Data Fusion Algorithm and Coal and Gas Outbursts Prediction
The prediction study on coal and gas outbursts is carried out by monitorisng some indices which are sensitive to the initiation of coal and gas outbursts.The values and changing rules of the irdices are the foundations of coal and gas outbursts prediction.But now,only the data of one key monitoring station is used in the coal and gas outbursts prediction practice,and the other data are ignored.In order to overcome the human factor and make full use of the monitoring information,the technique of multi-sensor target tracking is proposed to deal with the microseismic information.With the results of microseismic events,the activities of geological structure,fracture-depth of roof and floor,and the location of gas channel are obtained.These studies indicate that it is considerably possible to predict the coal and gas outbursts using microseismic monitoring with its inherent ability to remotely monitor the progressive failure caused by mining....
2020-06-12 16:17:21浏览：1431
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Chemical leaching of an Indian bituminous coal and characterization of the products by vibrational s
High volatile bituminous coal was demineralized by a chemical method.The vibrations of the "aromatics" structure of graphite,crystalline or non-crystalline,were observed in the spectra at the 1600 cm-1 region.The band at 1477 cm-1 is assigned as VR band,the band at 1392 cm-1 as VL band and the band at 1540 cm-1 as GR band.Graphite structure remains after chemical leaching liberates oxygenated functional groups and mineral groups.The silicate bands between 1010 and 1100 cm-1 are active in the infrared (IR) spectrum but inactive in the Raman spectrum.Absorption arising from C-H stretching in alkenes occurs in the region of 3000 to 2840 cm-1.Raman bands because of symmetric stretch of water molecules were also observed in the spectrum at 3250 cm-1 and 3450 cm-1.Scanning electron microscopy analysis revealed the presence of a graphite layer on the surface.Leaching of the sample with hydrofluoric acid decreases the mineral phase and increases the carbon content.The ash content is reduced by 84.5wt％ with leaching from its initial value by mainly removing aluminum and silicate containing minerals....
2020-06-12 16:17:20浏览：1421
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Experiment of Microwave Heating on Self-FluxingPellet Containing Coal
The self-fluxing pellets containing coal possess an independent self-reducing and self-slag-making system. A high metallization rate can be achieved without external reduction condition at high temperature, and it looks like a micro-blast-furnace by itself. The essential condition to use it is to supply heat to the pellet rapidly and uniformly and keep it at a certain temperature. Microwave heating can meet the need of rapid and uniform heating. The results show that the temperature of the pellet with a certain weight increases as the microwave power increases. The heating rate of the pellet is increased from 9.17 K/min (5 kW) to 71.65 K/min (15 kW)....
2020-06-12 16:17:18浏览：1423
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Model test of helical angle effect on coal loading performance of shear drum
The work presented in this paper focuses on improving coal loading performance of shear drum.Employing the similarity theory,we carried out a dimensional analysis of the correlation parameters which influence coal loading performance of shear drum.On the basis of similarity criterion,proportional relationship between the model and the prototype was taken on the condition of taking 1/3 as the similarity coefficient.Besides taking 1600 mm drum as the prototype,four helical angle models of shearer drums (15°,18°,21°,24°) were developed.Simultaneously,based on an established cutting test-bed,coal loading performance tests for the four drums were carried out at the same drum rotational and haulage speeds.After analyzing the data of coal-loading performance and torque,we concluded that:both the coal loading performance and torque vary along the track of the parabola with the opening side facing downwards;the best coal loading performance arises when the helical angle is at 19.3°,while the biggest torque arises at 22.1°;and the coal loading performance had nonlinear relationship with the torque....
2020-06-12 16:17:16浏览：1430
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Extraction of vanadium from stone coal by modified salt-roasting process
In order to reduce the pollution of Cl2 and HCl released during extracting vanadium from stone coal by sodium chloride roasting,a modified salt-roasting process was proposed by adding calcined lime in roasting process followed by H2SO4 leaching.The effects of parameters including roasting temperature,roasting time,addition mass ratio of NaCl,calcined lime upon leaching rate of vanadium and curing rate of chlorine were investigated,and the effects of leaching time and leaching temperature on leaching rate of vanadium were also studied.The results show that the vanadium leaching rate and the curing rate of chlorine are 67.3％ and 51.5％(mass fraction),respectively,at roasting temperature of 750 ℃,roasting time of 4 h,15％ sodium chloride and 8％ (mass fraction)calcined lime,leaching temperature of room temperature,and leaching time of 4 h....
2020-06-12 16:17:15浏览：1401
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Parametric study of electrostatic separation of South African fine coal
The fact that water requirements are a major problem for present and future developments in material beneficiation, and the construction of a new power plant in South Africa, forms the basis for the utilization of a Rotary Triboelectrostatic Separator (RTS) for beneficiation of South African pulverized coal. The cleaning potential of Majuba and Koorfontein coal was first evaluated using kinetic froth flotation tests on the -177μm coal fraction. The RTS tests were conducted under varied process parameters. Parameters such as applied separating voltage, air injection velocity, particle feed rate and splitter position were investigated. Two stage separation results show that the RTS reduced Majuba coal initially containing about 30% ash to a clean product of 14.30%, or 19.46%, ash at a combustible recovery of 15.10%, or 53.02%, respectively. Similar separation performance was also achieved with the Koorfontein coal. The mineral and organic compositions in the feed, after single stage and after the second stage separations were characterized using X-ray diffraction analysis. The results show a better separation for the second stage coal products....
2020-06-12 16:17:15浏览：1445
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Spectral characteristics of micro-seismic signals obtained during the rupture of coal
This study was performed to investigate the spectral characteristics of micro-seismic signals observed during the rupture of coal.Coal rupture micro-seismic observations were obtained on a test system that included an electro-hydraulic servo pressure tester controlled by a YAW microcomputer,a micro-seismic sensor,a loading system,and a signal collection system.The results show that the micro-seismic signal increases with increasing compressive stress at the beginning of coal rupture.The signal remains stable for a period at this stage.A large number of micro-seismic signals appear immediately before the main rupture event.The frequency of micro-seismic events reaches a maximum immediately after the coal ruptures.Micro-seismic signals were decomposed into several Intrinsic Mode Functions (IMF's) by the empirical mode decomposition (EMD) method using a Hilbert-Huang transform (HHT).The main frequency band of the micro-seismic signals was found to range from 10 to 100 Hz in the Hilbert energy spectrum and from marginal spectrum calculations.The advantage of applying an HHT is that this can extract the main features of the signal.This fact was confirmed by an HHT analysis of the coal micro-seismic signals that shows the technique is useful in the field of coal rupture....
2020-06-12 16:17:13浏览：1422
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Polycyclic aromatic hydrocarbon formation under simulated coal seam pyrolysis conditions
Coal seam pyrolysis occurs during coal seam fires and during underground coal gasification.This is an important source of polycyclic aromatic hydrocarbon (PAH) emission in China.Pyrolysis in a coal seam was simulated in a tubular furnace.The 16 US Environmental Protection Agency priority controlled PAHs were analyzed by HPLC.The effects of temperature,heating rate,pyrolysis atmosphere,and coal size were investigated.The results indicate that the 3-ring PAHs AcP and AcPy are the main species in the pyrolysis gas.The 2-ring NaP and the 4-ring Pyr are also of concern.Increasing temperature caused the total PAH yield to go through a minimum.The lowest value was obtained at the temperature of 600 ℃ Higher heating rates promote PAH formation,especially formation of the lower molecular weight PAHs.The typical heating rate in a coal seam,5 ℃/min,results in intermediate yields of PAHs.The total PAHs yield in an atmosphere of N2 is about 1.81 times that seen without added N2,which indicates that an air flow through the coal seam accelerates the formation of PAHs.An increase in coal particle size reduces the total PAHs emission but promotes the formation of 5- and 6-ring PAHs....
2020-06-12 16:17:13浏览：1419
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△P index with different gas compositions for instantaneous outburst prediction in coal mines
In this study we measured the △P(initial speed of gas emission)index with different gas concentrations of carbon dioxide(pure CO2,90% CO2+10% CH4,67% CO2+33% CH4,50% CO2+50% CH4,30% CO2+10% CH4 and pure CH4)of coal samples from the No.2 coal seam in the Yaojie Coal Mine,Gansu province,China.The effect of carbon dioxide concentration,gas composition,coal strength and particle size of coal samples on the △P index was investigated.The experimental results show that with gas of various compositions,the △P value of three samples were clearly different.The △P index of coal samples A,B and C(0.2～0.25 mm)were 4,6 and 7 with pure CH4 and 22,30 and 21 when pure CH4 was used.Carbon dioxide concentration affects the△P index markedly.The △P index increases with an increase in carbon dioxide concentration,especially for coal B.Hence,the△P index and K(another outburst index)values tested only with pure CH4 for prediction of the danger of outburst is not accurate.It is important to determine the initial speed of gas emission given the gas composition of the coal seam to be tested for exact outburst prediction....
2020-06-12 16:17:12浏览：1438
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Application of 3D Visual Techniques in Daliuta Coal Mine
3D visualization is one of major problems in "Digital Mine" theory and its technological research field. Through the observation of 3D geological models, spatial structural information, connected with the information of production management hidden in geological data, could be detected. In order to meet the requirement of more efficient coal exploration, a case study of geological characters of the Daliuta Coal Mine is presented in which 3D visual models of the ground surface and geologic bodies are established on the basis of data models and data structures of 3D geology modeling. The main conclusions of this study are as follows: (1) Through analysis and organization of spatial discrete data, the drillhole database is designed with the data of the Daliuta mine; the connections amomg drillhole data are realized and displayed in a 3D environment. (2) Combining real data of the Daliuta mine, drillhole visualization is realized in a 3D environment by using the CoalMiner system. (3) The ground surface modeling of the Daliuta coal mine adopted a surface-data model and a TIN data structure. (4) 3D models of coal seams and rock formations of the Daliuta mine are established, which provide a method for the simulation of complex surfaces of geologic bodies. In the end, the models are applied to the Daliuta coal mine and the result shows that better geological effects are obtained....
2020-06-12 16:17:12浏览：1422
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Unburned Carbon Loss in Fly Ash of CFB Boilers Burning Hard Coal
The unburned carbon loss in fly ash of circulating fluidized bed (CFB) boilers, most of which are burning active fuels such as lignite or peat, is normally very low. However, most CFB boilers in China usually burn hard coals such as anthracite and bituminous coal and coal wastes, so the carbon content in the fly ash from these boilers is higher than expected. This paper investigates the source of unburned carbon in the fly ash of CFB boilers burning hard coal through a series of field tests and laboratory investigations. The char behavior during combustion, including fragmentation and deactivation, which is related to the parent coal, has an important impact on the carbon burnout in CFB boilers. The research shows that char deactivation occurs during char burnout in fluidized bed combustion, especially for large particles of low rank coal. The uneven mixing of solids and air in the core region of the furnace also causes poor burnout of carbon in CFB fly ash. An index describing the volatile content (as dry ash free basis) over the heating value is proposed to present the coal rank. The coal combustion efficiency is shown to be strongly connected with this coal index. Several changes in the CFB boiler design are suggested to reduce the unburned carbon loss in the fly ash....
2020-06-12 16:17:10浏览：1396
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COAL DRY BENEFICIATION TECHNOLOGY IN CHINA: THE STATE-OF-THE-ART
In China, coal is the major source of energy and its leading role in energy consumption would not change in the next 50 years. Coal preparation is the essential component of Clean Coal Technology. In China more than two-thirds of available coal reserves are in arid areas, which results in the unfeasibility with conventional wet processing for coal preparation. The uniqueness of dry coal beneficiation technology with air-dense medium fluidized bed is discussed in this paper and a detailed survey of the current status of theoretical study, commercial application and development of the new technology is given in this paper....
2020-06-12 16:17:08浏览：1414
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Theoretical Models of Light Scattering Applied in Sizing Particles in Coal Water Slurry
Advantges and disadvantage of Mie scattering model and Fraunhofer diffraction model are discussed. The result shows that 1) the Fraunhofer diffraction model is simple in design and fast in operation, which is quite suitable for on-line control and 2) the intensity and energy distribution of diffracted light of both the Mie scattering model and the Fraunhofer theoretical model are compared and researched. Feasibility of using the Fraunhofer diffraction model to replace the Mie scattering model in measuring particles in coal water slurry is demonstrated....
2020-06-12 16:17:08浏览：1398
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Interregional coal flow and its environmental loads transfer in Shanxi Province
For the low price of coal and ineffective environmental management in mining area,China is in the dilemma of the increasing coal demand and the serious environmental issues in mining area.The more coal that is exported from a region,the more heavily it suffers from the environmental impacts of coal export.In this paper,the temporal and spatial process of exporting coal from Shanxi to other provinces of China is traced between 1975 and 2005.The coal net export of Shanxi increased to 370.69 million tonnes in 2005,representing an average annual growth rate of 7.5％ from 1975 to 2005.With the increase of the amount of coal export from Shanxi,the Environmental Loads Transfer (ELT) that import provinces input to mining areas of Shanxi are rising.Effective means of internalizing the environmental externality of ELT lie in:1) setting up a coal sustainable development fund to restore environment of coal mining area; 2) enforcing environment tax,financial transfer payment and transferring advantage technology of pollution reduction to coal export area; and 3) reducing coal regional flow by reducing coal demand from power generation and heating and other industries....
2020-06-12 16:17:07浏览：1429
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