-
Prediction of operational parameters effect on coal flotation using artificial neural network
Artificial neural network procedures were used to predict the combustible value (i.e. 100-Ash) and combustible recovery of coal flotation concentrate in different operational conditions. The pulp density, pH, rotation rate, coal particle size, dosage of collector, frother and conditioner were used as inputs to the network. Feed-forward artificial neural networks with 5-30-2-1 and 7-10-3-1 arrangements were capable to estimate the combustible value and combustible recovery of coal flotation concentrate respectively as the outputs. Quite satisfactory correlations of 1 and 0.91 in training and testing stages for combustible value and of 1 and 0.95 in training and testing stages for combustible recovery prediction were achieved. The proposed neural network models can be used to determine the most advantageous operational conditions for the expected concentrate assay and recovery in the coal flotation process....
2020-06-12 16:17:55浏览：1395
查看 -
Dynamic subsidence basins in coal mines based on rock mass theological theory
In order to investigate the surface deformation caused by coal mining and to reduce environmental damage,more accurate information of dynamic subsidence basins,caused by coal mining,is needed.Based on rheological theory,we discuss surface deformation mechanism of dynamic subsidence on the assumption that both the roof and the coal seam are visco-elastic media,put forward the idea that the principle of surface deformation is similar to that of roofs,except for their parameters.Therefore,a surface deformation equation can be obtained,given the equation of the roof deformation derived.from using a HM rheological model.In the end,we apply the equation of surface deformation as a practical subsidence prediction in a coal mine.Given the rheologic properties of a rock mass,the results of our research of a dynamic subsidence basin can predict the development of surface deformation as a function of time.which is more important than the ultimate subsidence itself.The results indicate that using rheological theory to calculate the deformation of a dynamic subsidence basin is suitable and provides some reference for surface deformation of dynamic subsidence basins....
2020-06-12 16:17:55浏览：1395
查看 -
Response of coal reservoir porosity to magma intrusion in the Shandong Qiwu Mine, China
The Qiwu Mine is located in the Ten Xian coal field of Shandong province. It experienced repeated volcanic activity, after the coal beds formed, where magma intrusion was significant. The effect of coal reservoir porosity after magma intrusion was studied by analysis of regional and mine structure and magmatic activity. Experimental methods including maceral measurement under the microscope and mercury porosimetry were used for testing the pore structure. The authors believe that magma intrusion into low-rank bituminous coal causes reservoir porosity to gradually increase: the closer to the magmatic rock a sample is, the less the porosity. The pore size distribution also changes. In the natural coal bed the pore size is mainly in the transitive and middle pore range. However, the coal changes to anthracite next to the magmatic rock and larger pores dominate. Regional magma thermal evolution caused coal close to magmatic rock to be roasted, which reduced the volatile matter, developed larger holes, and destroyed plant tissue holes. The primary reason for a porosity decrease in the vicinity of magmatic rock is that Bituminite resulting from the roasting fills the holes that were present initially....
2020-06-12 16:17:52浏览：1432
查看 -
Upgrading of Yi'an gas coal by low temperature pyrolysis under different atmospheres
The quality of Yi'an gas coal before and after low temperature upgrading under either a N2 or H2 atmosphere was examined by thermogravimetric and infrared analyses.The effect of upgrading on the prepared coke quality was analyzed.The results show that the carboxyl and phenolic hydroxyls in the coal molecular structure are removed after upgrading by low temperature pyrolysis under either N2 or H2 atmospheres.This improves coal caking properties to a certain extent.The upgrading effect under a H2 atmosphere is remarkably better than the effect observed after upgrading under N2.Compared to coke obtained from raw coal,the compressive- and micro-strength of the cokes obtained from upgraded coal are greatly improved.The effect on coke reactivity with CO2 is not significant.The best upgrading temperature for Yi'an gas coal under either a N2 or H2 atmosphere is 250 or 275 ℃ respectively....
2020-06-12 16:17:52浏览：1421
查看 -
Prognosis of residual coal gas capacity made by the 'Express' method
An easy, reliable, and inexpensive method, called ‘Express' method, was described to determine the residual gas capacity of deep mines using results from an air and gas balance. Air and gas balances are common elements of mine management and must be performed periodically. Using the process described here to obtain balance results, it is straightforward to obtain the residual gas capacity, which is an important parameter for decision-making in current mine operations. After a mine is closed, the residual gas capacity becomes a dominant factor used to select methods to protect against gas emissions from the closed underground area or perhaps to provide information for the use of purpose to date....
2020-06-12 16:17:48浏览：1455
查看 -
An OGC standard-oriented architecture for distributed coal mine map services
GIS- or CAD-based technology has been widely used for cartographic maps in coal mines, but structural gaps between such maps make it difficult to provide an integrated map service, for any specific purpose, at higher levels. There is no uniform platform that can be used to manage all involved maps. The main reason for this is that datasets are submitted by individual coal mines using their individual, diverse software. No consistent model is used within the software for data abstraction and symbolization. This paper first reviews all the essential specifications concerning OGC (Open Geospatial Consortium) interoperability. Then an OGC standard-oriented architecture is proposed to provide distributed coal mine map services. Within this new architecture the management of spatial data archives, and the integration of coal mine maps, are achieved through the interfaces of geospatial services. Finally an open source geospatial approach is suggested to implement the proposed scheme. A case study of the Huaibei Coal Group is used to demonstrate the proposal....
2020-06-12 16:17:47浏览：1420
查看 -
Settlement behavior of coal mine waste in different surrounding rock conditions
In order to investigate the influence of complex conditions of in-situ surrounding rocks on the settlement behavior of nubbly coal mine waste subjected to high gravity pressure, four kinds of loading chambers made of different similar materials with different elastic moduli in experiments were used to simulate the deformation features of in-site rocks, including soft, moderate hardness, hard and extra-hard rocks. The results show that all the settlement-axial load (or axial strain-stress) curves obtained under four different surrounding rock conditions present power-exponential function feature. The final settlement of coal mine waste under the same axial load is closely related to the lumpiness gradations and the deformation behavior of chamber materials used to simulate behaviors of different in-situ surrounding rocks. In the same surrounding rock condition, the final settlement under the same maximum axial load decreases with the decrease of the proportion of larger gradation of coal mine waste. While for the same lumpiness gradation case, the settlement increases with the decrease of elastic modulus of simulated surrounding rocks and the lateral pressure induced by axial load increases with the increase of elastic modulus of loading chambers that are used to simulate different surrounding rocks. The test results also reveal that both the compaction curve and lateral pressure curve show a three-stage behavior, and the duration of each stage, which is closely related to gradations and the deformation feature of loading chamber materials, decreases with the increase of the proportion of the small size of coal mine waste and elastic modulus of the simulated rock materials....
2020-06-12 16:17:47浏览：1435
查看 -
Enhanced anaerobic biodegradability of real coal gasification wastewater with methanol addition
Coal gasification effluent is a typical refractory industrial wastewater with a very poor anaerobic biodegradability due to its toxicity. Methanol was introduced to improve anaerobic biodegradability of real coal gasification wastewater, and the effect of methanol addition on the performance was investigated in a mesophilic upflow anaerobic sludge bed reactor with a hydraulic retention time of 24 hr. Experimental results indicated that anaerobic treatment of coal gasification wastewater was feasible with the addition of methanol. The corresponding maximum COD and phenol removal rates were 71% and 75%, respectively, with methanol concentration of 500 mgCOD/L for a total organic loading rate of 3.5 kg COD/(m3·day) and a phenol loading rate of 0.6 kg/(m3·day). The phenol removal rate was not improved with a higher methanol concentration of 1000 mg COD/L. Substrate utilization rate (SUR) tests indicated that the SURs of phenol were 106, 132, and 83 mg phenol/(g VSS.day) at methanol concentrations of 250, 500, and 1000 mg COD/L, respectively, and only 45 mg phenol/(g VSS.day) in the control reactor. The presence of methanol could reduce the toxicity of coal gasification wastewater and increase the biodegradation of phenolic compounds....
2020-06-12 16:17:46浏览：1404
查看 -
Radiant Image Simulation of Pulverized Coal Combustion in Blast Furnace Raceway
The relationship between two-dimensional radiant image and three-dimensional radiant energy in blast furnace raceway was studied by numerical simulation of combustion process. Taking radiant image as radiant boundary for numerical simulation of combustion process, the uneven radiation parameter can be calculated. A method to examine three-dimensional temperature distribution in blast furnace raceway was put forward by radiant image processing. The numeral temperature field matching the real combustion can be obtained by proposed numeric image processing technique....
2020-06-12 16:17:43浏览：1420
查看 -
The coal cleat system:A new approach to its study
After a general analysis regarding the concept of coal “cleat system”, its genetic origin and practical applications to coalbed methane (CBM) commercial production and to CO2 geological sequestration projects, the authors have developed a method to answer, quickly and accurately in accordance with the industrial practice and needs, the following yet unanswered questions: (1) how to define the spatial orientation of the different classes of cleats presented in a coal seam and (2) how to determine the frequency of their connectivites. The new available and presented techniques to answer these questions have a strong computer based tool (geographic information system, GIS), able to build a complete georeferentiated database, which will allow to three-dimensionally locate the laboratory samples in the coalfield. It will also allow to better understand the coal cleat system and consequently to recognize the best pathways to gas flow through the coal seam. Such knowledge is considered crucial for under-standing what is likely to be the most efficient opening of cleat network, then allowing the injection with the right spatial orientation, of pressurized fluids in order to directly drain the maximum amount of gas flow to a CBM exploitation well. The method is also applicable to the CO2 geological sequestration technologies and operations corresponding to the injection of CO2 sequestered from industrial plants in coal seams of abandoned coal mines or deep coal seams....
2020-06-12 16:17:42浏览：1425
查看 -
Reaction Kinetic Equation for Char Combustion of Underground Coal Gasification
Based on the quasi-steady-state approximation, the dynamic equation of char combustion in the oxidation zone of underground coal gasification (UCG) was derived. The parameters of the dynamic equation were determined at 900℃ using a thermo-gravimetric (TG) analyzer connected to a flue gas analyzer and this equation. The equation was simplified for specific coals, including high ash content, low ash content, and low ash fusibility ones. The results show that 1) the apparent reaction rate constant increases with an increase in volatile matter value as dry ash-free basis, 2) the effective coefficient of diffusion decreases with an increase in ash as dry basis, and 3) the mass transfer coefficient is independent of coal quality on the whole. The apparent reaction rate constant, mass-transfer coefficient and effective coefficient of diffusion of six char samples range from 7.51×104 m/s to 8.98×104 m/s, 3.05×106 m/s to 3.23×106 m/s and 5.36×106 m2/s to 8.23×106 m2/s at 900℃, respectively....
2020-06-12 16:17:42浏览：1405
查看 -
Preparation of Activated Carbon Functional Ceramics From Coal Pitch
The influences of different impregnation temperatures, pre-oxidation, carbonization temperatures and activation conditions on the iodine value and carbon deviations was discussed.SEM, EDS, and BET techniques were used to investigate the microstructures and properties of materials.Results showed that activated carbon functional ceramic exhibited excellent comprehensive properties when porous ceramics adsorbed the coal pitch at 150 ℃ for 0.5 h, oxidized at 420 ℃ for 1.0 h, and carbonizated at 700 ℃ for 1.0 h and then activated by using KOH (20wt%) as agent at 800 ℃ for 1.0 h, as confirmed by the high iodine value (162.6 mg/g) and high specific surface area (83.5 m...
2020-06-12 16:17:41浏览：1436
查看 -
A general solution and approximation for the diffusion of gas in a spherical coal sample
The square root relationship of gas release in the early stage of desorption is widely used to provide a simple and fast estimation of the lost gas in coal mines. However, questions arise as to how the relation-ship was theoretically derived, what are the assumptions and applicable conditions and how large the error will be. In this paper, the analytical solutions of gas concentration and fractional gas loss for the dif-fusion of gas in a spherical coal sample were given with detailed mathematical derivations based on the diffusion equation. The analytical solutions were approximated in case of small values of time and the error analyses associated with the approximation were also undertaken. The results indicate that the square root relationship of gas release is the first term of the approximation, and care must be taken in using the square root relationship as a significant error might be introduced with increase in the lost time and decrease in effective diameter of a spherical coal sample....
2020-06-12 16:17:40浏览：1422
查看 -
Experimental Research on Pore Structure and Gas Adsorption Characteristic of Deformed Coal
The pore structure and gas adsorption property of deformed coal with different degrees of metamorphism were tested by low-temperature nitrogen adsorption and isothermal adsorption experiments. The fractal theory and the Langmuir adsorption theory were used to analyze the experimental data. The test results showed that the deformed coal had more het-erogeneous pore structures and open pores, and its speciifc surface area (SSA) and fractal dimension (D) were higher. There is a polynomial relationship between D and speciifc surface area as well as gas adsorption capacity (VL). The gas adsorption capacity of deformed coal is inlfuenced by pore structure, coal rank, deformation and stress together, among which the pore structure is the main inlfuencing factor for the adsorption capacity of deformed coal. The test pressure could affect the ac-curacy of the adsorption constants a and b, so the highest experiment pressure should be greater than the actual pressure of coal seam in order to reduce the deviation of adsorption constants....
2020-06-12 16:17:39浏览：1454
查看 -
Separation of arenols from a high-temperature coal tar
A high-temperature coal tar collected from Xuzhou Coking Plant,Saint-Gobain Pipelines (Xuzhou) Co.,Ltd.was exhaustively extracted with petroleum ether (PE).The extract was sequentially eluted through silica gel with PE and PE/ethyl acetate (EA) mixed solvents (volume ratio 2:1 ) to afford two eluted fractions.The extract and eluted fractions were analyzed with gas chromatography/mass spectrometry.In total,14 arenols were detected,including phenol,cresols,xylenols,fluorenols,phenanthren-3-ol and pyren-1-ol....
2020-06-12 16:17:39浏览：1434
查看
