All coal preparation in which fine coal is handled depends to some extent on the wettability of coal surface by water. The content of external water in fine moist material plays significant role on screening. This art...All coal preparation in which fine coal is handled depends to some extent on the wettability of coal surface by water. The content of external water in fine moist material plays significant role on screening. This article probed into the causations why fine moist materials adhere to the screen deck on common vibrator in the process of screening. Although the wetting that results from interactions between the coal surface and water molecules that are determined by the composition of coal matrix (interrelated with coal rank) and heterogeneous constituents such as oxygen function groups, mineral impurities and pores have something to do with adhering, we found that the effect of wettability is not the key causation to agglomeration, in other words, water bridges among particles are the key causation to the fine moist materials’ adhesion. This paper also shows how the capillary adhesive forces forms and how to calculate and measure these forces.展开更多
During screening operation, blinding or clogging of screen perforations generally occurs to reduce the sieving capacity and efficiency. Recently, the flip-flow screening has been widely recognized as a feasible method...During screening operation, blinding or clogging of screen perforations generally occurs to reduce the sieving capacity and efficiency. Recently, the flip-flow screening has been widely recognized as a feasible method to deal with the problem. In this paper, a novel centralized-driving flip-flow screen(CFS) was developed for the separation of fine and moist coal, and the key structures, namely, a centralized-driving mechanism and a quasi-circle beam mounted with the mat were designed for high reliability and stability. By means of a test on an experimental prototype, the effect of some factors, i.e., initial stretch and hardness of the polyurethane panel, respectively, and the rotation speed of the driving motor on the kinematic characteristic of the screen surface was investigated. Results show that without an initial stretch, the sieve mat generates the largest vibratory amplitude while the slacker the sieve mat initially is, the smaller amplitude it will accomplish. And an increase in the rotation speed could cause a rise in the vibratory amplitude. Unlike the two factors, the hardness does not have a definite effect on the kinematic performance, on which a further study is required. Finally, screening processing on a laboratory prototype was conducted to draw the conclusion that the developed CFS also has a high sieving efficiency for the fine and moist coal.展开更多
The Probability Sizing Screen (PSS) developed by China University of Mining and Technology has been used since 1980 for the screening of moist fine raw coal. More than 600PSS's have been installed in Chinese coal ...The Probability Sizing Screen (PSS) developed by China University of Mining and Technology has been used since 1980 for the screening of moist fine raw coal. More than 600PSS's have been installed in Chinese coal mines, bringing about economic benefits to both coal producers and consumers in terms of reduced energy saving, transpertation cost reduction,and environmental protection. While the PSS treats some high-moisture fine raw coal, the mesh apertures may be blinded by the fine particles stuck on the mesh wire of the screen. Recently, the authors have developed the Piano-wire Probability Screen, a new screen which screens moist fine raw coal. This screen assimilates advantages of PSS, having large deck inclination, large aperture and multideck. In addition the new screen uses piano-wire decks which have a new structure, great open area, and no blinding. The results of sizing fine moist raw coal in Lugou Coal Mine, Henan Province,show that the Piano-wire Probability Screen has a large capacity and high efficiency and is an efficient screen for separating moist raw coal with diameter of 6mm. This paper describes the results of fundamental studies on the Piano-wire Probability Screen. and also includes data from pilot-plant studies.展开更多
The synthetic index K s for evaluating flip-flow screens is proposed and systematically optimized in view of the whole system. A series of optimized values of relevant parameters are found and then compared with those...The synthetic index K s for evaluating flip-flow screens is proposed and systematically optimized in view of the whole system. A series of optimized values of relevant parameters are found and then compared with those of the current industrial specifications. The results show that the optimized value K s approaches the one of those famous flip-flow screens in the world. Some new findings on geometric and kinematics parameters are useful for improving the flip-flow screens with a low K s value, which is helpful in developing clean coal technology.展开更多
The fine-structure energy levels of 1s2s and 1s2p atomic states for the He-like Ar ion immersed in dense plasmas are calculated. The ion sphere model is used to describe the plasma screening effect on the tested ion. ...The fine-structure energy levels of 1s2s and 1s2p atomic states for the He-like Ar ion immersed in dense plasmas are calculated. The ion sphere model is used to describe the plasma screening effect on the tested ion. The influences of the hard sphere confinement and plasma screening on the fine-structure energy levels are investigated respectively. The calculated results show that the confined effect of the hard sphere on the fine-structure energy levels increases with decreasing hard sphere radius, and the plasma screening effect on the fine-structure energy levels increases with the increase of free electron density. In dense plasmas, the confined effect of the hard sphere on the fine-structure energy levels can be neglected generally, compared with the contribution from free electron screening. An interesting phenomenon about the energy level crossing is found among 1s2s(~1S_0) and 1s2p(~3P_(0,1)) atomic states. The results reported at the present work are useful for plasma diagnostics.展开更多
文摘All coal preparation in which fine coal is handled depends to some extent on the wettability of coal surface by water. The content of external water in fine moist material plays significant role on screening. This article probed into the causations why fine moist materials adhere to the screen deck on common vibrator in the process of screening. Although the wetting that results from interactions between the coal surface and water molecules that are determined by the composition of coal matrix (interrelated with coal rank) and heterogeneous constituents such as oxygen function groups, mineral impurities and pores have something to do with adhering, we found that the effect of wettability is not the key causation to agglomeration, in other words, water bridges among particles are the key causation to the fine moist materials’ adhesion. This paper also shows how the capillary adhesive forces forms and how to calculate and measure these forces.
基金The financial support from the National Natural Science Foundation of China (Nos. 51221462 and 51134022)the Doctoral Programs Foundation of Ministry of Education of China (No. 20120095110001)
文摘During screening operation, blinding or clogging of screen perforations generally occurs to reduce the sieving capacity and efficiency. Recently, the flip-flow screening has been widely recognized as a feasible method to deal with the problem. In this paper, a novel centralized-driving flip-flow screen(CFS) was developed for the separation of fine and moist coal, and the key structures, namely, a centralized-driving mechanism and a quasi-circle beam mounted with the mat were designed for high reliability and stability. By means of a test on an experimental prototype, the effect of some factors, i.e., initial stretch and hardness of the polyurethane panel, respectively, and the rotation speed of the driving motor on the kinematic characteristic of the screen surface was investigated. Results show that without an initial stretch, the sieve mat generates the largest vibratory amplitude while the slacker the sieve mat initially is, the smaller amplitude it will accomplish. And an increase in the rotation speed could cause a rise in the vibratory amplitude. Unlike the two factors, the hardness does not have a definite effect on the kinematic performance, on which a further study is required. Finally, screening processing on a laboratory prototype was conducted to draw the conclusion that the developed CFS also has a high sieving efficiency for the fine and moist coal.
基金This project is supported by the special fund of Chinese institutions of higher learning
文摘The Probability Sizing Screen (PSS) developed by China University of Mining and Technology has been used since 1980 for the screening of moist fine raw coal. More than 600PSS's have been installed in Chinese coal mines, bringing about economic benefits to both coal producers and consumers in terms of reduced energy saving, transpertation cost reduction,and environmental protection. While the PSS treats some high-moisture fine raw coal, the mesh apertures may be blinded by the fine particles stuck on the mesh wire of the screen. Recently, the authors have developed the Piano-wire Probability Screen, a new screen which screens moist fine raw coal. This screen assimilates advantages of PSS, having large deck inclination, large aperture and multideck. In addition the new screen uses piano-wire decks which have a new structure, great open area, and no blinding. The results of sizing fine moist raw coal in Lugou Coal Mine, Henan Province,show that the Piano-wire Probability Screen has a large capacity and high efficiency and is an efficient screen for separating moist raw coal with diameter of 6mm. This paper describes the results of fundamental studies on the Piano-wire Probability Screen. and also includes data from pilot-plant studies.
文摘The synthetic index K s for evaluating flip-flow screens is proposed and systematically optimized in view of the whole system. A series of optimized values of relevant parameters are found and then compared with those of the current industrial specifications. The results show that the optimized value K s approaches the one of those famous flip-flow screens in the world. Some new findings on geometric and kinematics parameters are useful for improving the flip-flow screens with a low K s value, which is helpful in developing clean coal technology.
基金Project supported by the National Natural Science Foundation of China(Grant No.11474208)the Doctoral Science Foundation of Longdong University,China(Grant No.XYBY1704)
文摘The fine-structure energy levels of 1s2s and 1s2p atomic states for the He-like Ar ion immersed in dense plasmas are calculated. The ion sphere model is used to describe the plasma screening effect on the tested ion. The influences of the hard sphere confinement and plasma screening on the fine-structure energy levels are investigated respectively. The calculated results show that the confined effect of the hard sphere on the fine-structure energy levels increases with decreasing hard sphere radius, and the plasma screening effect on the fine-structure energy levels increases with the increase of free electron density. In dense plasmas, the confined effect of the hard sphere on the fine-structure energy levels can be neglected generally, compared with the contribution from free electron screening. An interesting phenomenon about the energy level crossing is found among 1s2s(~1S_0) and 1s2p(~3P_(0,1)) atomic states. The results reported at the present work are useful for plasma diagnostics.
