In this paper, the desulphurisation of high sulphur low-rank coal is proposed as a raw material for pulverised coal injection technology. Therefore, the influence of oxidant linear velocity and the size of the coal gr...In this paper, the desulphurisation of high sulphur low-rank coal is proposed as a raw material for pulverised coal injection technology. Therefore, the influence of oxidant linear velocity and the size of the coal grain was investigated in a fluidised bed. The hydrodynamic parameters of the fluidised bed including： porosity, Sherwood criterion （diffusion Nusselt number）, and mass transfer coefficient （external surface） were calculated. Furthermore, the study examined the effects of intensity and efficiency on the desulphurised coal properties; organic matter, ash, and volatile matter contents. The key changes during the conversion of pyritic sulphur and coal organic matter were subsequently examined. The results showed that the sulphur content （St^d 3.16 wt%） of the low-rank coal, was transformed to （St^d 〈 1.5 wt%） after desulfurization. Other enhanced properties were： V^daf ≤ 38.0 wt%; A^d 〈 10.0 wt%, now suitable for pulverised coal injection technology.展开更多
Considerable amounts of coal particles are accumulated in the tailing dams of washing plants which can make serious environmental problems. Recovery of these particles from tailings has economically and environmentall...Considerable amounts of coal particles are accumulated in the tailing dams of washing plants which can make serious environmental problems. Recovery of these particles from tailings has economically and environmentally several advantages. Maintaining natural resources and reducing discharges to the dams are the most important ones. This study was examined the possibility to recover coal particles from a tailing dam with 56.29% ash content by using series of processing techniques. For this purpose, gravity separation （jig, shaking table and spiral） and flotation tests were conducted to upgrade products. Based the optimum value of these processing methods, a flowsheet was designed to increase the rate of recovery for a wide range of coal particles. Results indicated that the designed circuit can recover over 90% of value coal particles and reduce ash content of product to less than 14%. These results can potentially be used for designing an industrial operation as a recycling plant and an appropriate instance for other areas to reduce the environmental issues of coal tailing dams.展开更多
By using the matrix theory, a 5 parameter grinding mathematical model is established. Based on the properties of feed coal and requirements for size distribution of final product, the model gives the required grinding...By using the matrix theory, a 5 parameter grinding mathematical model is established. Based on the properties of feed coal and requirements for size distribution of final product, the model gives the required grinding probability for various particles and corresponding ball size distribution. By using this model, 3 different sizes of ball mill are designed and put into commercial use for coal water fuel. The forecasted ball mill capacity, the particle sizes and particle size distribution as well as the coal water fuel quality parameters are all in line with industrial operation results, which have proved the suitability of the model.展开更多
"Riding mining" is a form of mining where the working face is located above the roadway and advances parallel to it.Riding mining in deep soft rock creates a particular set of problems in the roadway that in..."Riding mining" is a form of mining where the working face is located above the roadway and advances parallel to it.Riding mining in deep soft rock creates a particular set of problems in the roadway that include high stresses,large deformations,and support difficulties.Herein we describe a study of the rock deformation mechanism of a roadway as observed during riding mining in deep soft rock.Theoretical analysis,numerical simulations,and on site monitoring were used to examine this problem.The stress in the rock and the visco-elastic behavior of the rock are considered.Real time data,recorded over a period of 240 days,were taken from a 750 transportation roadway.Stress distributions in the rock surrounding the roadway were studied by comparing simulations to observations from the mine.The rock stress shows dynamic behavior as the working face advances.The pressure increases and then drops after peaking as the face advances.Both elastic and plastic deformation of the surrounding rock occurs.Plastic deformation provides a mechanism by which stress in the rock relaxes due to material flow.A way to rehabilitate the roadway is suggested that will help ensure mine safety.展开更多
In the procedure of coal industry production, the losses of the persons and economy caused by the gas explosion accidents are most serious, therefore, prevention and control of the gas explosion accident of the coal m...In the procedure of coal industry production, the losses of the persons and economy caused by the gas explosion accidents are most serious, therefore, prevention and control of the gas explosion accident of the coal mines is an important issue needed to be solved urgently in the safety production work of our coal mines. The characteristic of time structure variation index characteristic was analyzed about gas concentration sequence of three measure points in the NO. 1I 1024 working face. It was found that the value of time variation about three measure points was mostly 1〈δ≤1.5, and gas emission presented consistently strong-clustering state twice, and the value of time variation presented continuous variation state in the active stage of gas concentration. Complex characteristics of the value indicated gas emission was continuously variable in time or space and presented the complex nonlinear characteristics. So the characteristic about gas emission system was correctly depicted and analyzed to gas emission system according to the relation of its state variation and essential of nonlinear system. The result also provided reliable warranty for its continued nonlinear research on gas emission.展开更多
It has been possible to pelletize wood Miscanthus mixtures （12.5%, 25% and 50%） without modifying production process settings of a softwood pellets plant. Pure Miscanthus material tested in the same conditions has l...It has been possible to pelletize wood Miscanthus mixtures （12.5%, 25% and 50%） without modifying production process settings of a softwood pellets plant. Pure Miscanthus material tested in the same conditions has led to unstable production, mainly explained by hammermill overfeeding. The unstable production has been identified as the main responsible factor of the low quality of pellets produced with pure Miscanthus for these trials. The produced pellets were tested in a 25 kW boiler and compared with agro-pellets of various origins： winter barley straw, rapeseed straw, reed, old hay, Miscanthus, and wood pellets. Results gained during these combustion trials allowed to describe combustion of these uncommon fuels and to characterize its emissions. The trials confirm general characteristics of agricultural fuel combustion： influence of the ash content on the gross calorific value, influence of the N content in the fuel on the NOx emissions, influence on the alkali content on the C12 emissions. But the influence of known parameter （S. alkali and earth alkali content） on SO2 emission might not be highlighted, while a relation with the fuel moisture content could be considered.展开更多
文摘In this paper, the desulphurisation of high sulphur low-rank coal is proposed as a raw material for pulverised coal injection technology. Therefore, the influence of oxidant linear velocity and the size of the coal grain was investigated in a fluidised bed. The hydrodynamic parameters of the fluidised bed including： porosity, Sherwood criterion （diffusion Nusselt number）, and mass transfer coefficient （external surface） were calculated. Furthermore, the study examined the effects of intensity and efficiency on the desulphurised coal properties; organic matter, ash, and volatile matter contents. The key changes during the conversion of pyritic sulphur and coal organic matter were subsequently examined. The results showed that the sulphur content （St^d 3.16 wt%） of the low-rank coal, was transformed to （St^d 〈 1.5 wt%） after desulfurization. Other enhanced properties were： V^daf ≤ 38.0 wt%; A^d 〈 10.0 wt%, now suitable for pulverised coal injection technology.
文摘Considerable amounts of coal particles are accumulated in the tailing dams of washing plants which can make serious environmental problems. Recovery of these particles from tailings has economically and environmentally several advantages. Maintaining natural resources and reducing discharges to the dams are the most important ones. This study was examined the possibility to recover coal particles from a tailing dam with 56.29% ash content by using series of processing techniques. For this purpose, gravity separation （jig, shaking table and spiral） and flotation tests were conducted to upgrade products. Based the optimum value of these processing methods, a flowsheet was designed to increase the rate of recovery for a wide range of coal particles. Results indicated that the designed circuit can recover over 90% of value coal particles and reduce ash content of product to less than 14%. These results can potentially be used for designing an industrial operation as a recycling plant and an appropriate instance for other areas to reduce the environmental issues of coal tailing dams.
文摘By using the matrix theory, a 5 parameter grinding mathematical model is established. Based on the properties of feed coal and requirements for size distribution of final product, the model gives the required grinding probability for various particles and corresponding ball size distribution. By using this model, 3 different sizes of ball mill are designed and put into commercial use for coal water fuel. The forecasted ball mill capacity, the particle sizes and particle size distribution as well as the coal water fuel quality parameters are all in line with industrial operation results, which have proved the suitability of the model.
基金Supported by the National Natural Science Foundation of China (Nos. 50834005 and 51074163)the Ministry of Education Support Program for New Century Excellent of China(No. NCET-08-0837)+1 种基金the Fundamental Research Funds for the Central Universities of ChinaYouth Science and Technology Foundation of China University of Mining and Technology(No. 2010QNB25)
文摘"Riding mining" is a form of mining where the working face is located above the roadway and advances parallel to it.Riding mining in deep soft rock creates a particular set of problems in the roadway that include high stresses,large deformations,and support difficulties.Herein we describe a study of the rock deformation mechanism of a roadway as observed during riding mining in deep soft rock.Theoretical analysis,numerical simulations,and on site monitoring were used to examine this problem.The stress in the rock and the visco-elastic behavior of the rock are considered.Real time data,recorded over a period of 240 days,were taken from a 750 transportation roadway.Stress distributions in the rock surrounding the roadway were studied by comparing simulations to observations from the mine.The rock stress shows dynamic behavior as the working face advances.The pressure increases and then drops after peaking as the face advances.Both elastic and plastic deformation of the surrounding rock occurs.Plastic deformation provides a mechanism by which stress in the rock relaxes due to material flow.A way to rehabilitate the roadway is suggested that will help ensure mine safety.
基金Supported by Project Provincial Natural Science Foundation of Hunan （09J J3126） The Doctoral Research Activating Fund of Xiangtan University （09QDZ13, 10QDZ04）
文摘In the procedure of coal industry production, the losses of the persons and economy caused by the gas explosion accidents are most serious, therefore, prevention and control of the gas explosion accident of the coal mines is an important issue needed to be solved urgently in the safety production work of our coal mines. The characteristic of time structure variation index characteristic was analyzed about gas concentration sequence of three measure points in the NO. 1I 1024 working face. It was found that the value of time variation about three measure points was mostly 1〈δ≤1.5, and gas emission presented consistently strong-clustering state twice, and the value of time variation presented continuous variation state in the active stage of gas concentration. Complex characteristics of the value indicated gas emission was continuously variable in time or space and presented the complex nonlinear characteristics. So the characteristic about gas emission system was correctly depicted and analyzed to gas emission system according to the relation of its state variation and essential of nonlinear system. The result also provided reliable warranty for its continued nonlinear research on gas emission.
文摘It has been possible to pelletize wood Miscanthus mixtures （12.5%, 25% and 50%） without modifying production process settings of a softwood pellets plant. Pure Miscanthus material tested in the same conditions has led to unstable production, mainly explained by hammermill overfeeding. The unstable production has been identified as the main responsible factor of the low quality of pellets produced with pure Miscanthus for these trials. The produced pellets were tested in a 25 kW boiler and compared with agro-pellets of various origins： winter barley straw, rapeseed straw, reed, old hay, Miscanthus, and wood pellets. Results gained during these combustion trials allowed to describe combustion of these uncommon fuels and to characterize its emissions. The trials confirm general characteristics of agricultural fuel combustion： influence of the ash content on the gross calorific value, influence of the N content in the fuel on the NOx emissions, influence on the alkali content on the C12 emissions. But the influence of known parameter （S. alkali and earth alkali content） on SO2 emission might not be highlighted, while a relation with the fuel moisture content could be considered.
