Study On X-ray Recognition Technology Of Coal And Gangue In Intelligent Separation Process

With the development of clean coal technology,people pay more and more attention to the work of the discharging gangue before coal preparation of raw coal.The traditional techniques of discharging gangue mainly include manual sorting and wet discharging gangue.But these methods have the disadvantages of low efficiency and environmental pollution.In view of these shortcomings,the intelligent separation method of coal and gangue based on dual-energy X-ray is proposed.The experimental research on the recognition technology of the sorting system was carried out.The intelligent separation system of coal and gangue based on dual-energy X-ray is used as the test platform.Based on coal analysis and MATLAB software,the imaging characteristics and recognition process of coal and gangue were studied through experiments.Then,three kinds of raw coal(coking coal,fat coal,gas coal)with different densities and particle sizes were prepared by screening and float-and-sink test.The ash content of three kinds of coal samples was determined.A linear relationship model between density and ash content is established.The qualitative and quantitative analysis of the mineral composition of raw coal are carried out by XRD.Based on the ash content of raw coal and the law of conservation of mass,the content of each mineral in the raw coal are calculated.Then the X-ray images of coal and gangue are processed by MATLAB software.The imaging characteristics of coal and gangue in X-ray high and low energy regions are analyzed.The imaging characteristics of coal and gangue in the high and low energy regions of X-ray and the distribution characteristics of their respective gray values in the gray histogram are analyzed.By analyzing the gray value change rules of three kinds of raw coal under different conditions,it is concluded that the gray value change of raw coal is the result of the interaction of density and thickness.The change of gray value of raw coal with density mainly stems from the difference of mineral composition of raw coal at different density levels.The exponential decay relationship model between gray value with density and thickness of raw coal is established by regression analysis.The mass absorption coefficients of different kinds of coal and gangue in different energy regions are obtained.The relationship between mass absorption coefficient and mineral composition and content is explained by the theory of equivalent atomic number.It is concluded that the difference of the X-ray attenuation effect between coal and gangue is mainly due to the difference of mineral composition between them.Finally,the disadvantages of recognizing coal and gangue by gray value method are analyzed.The principle of recognizing coal and gangue by R-value method is expounded and the separation threshold of coal and gangue is established.And the recognition tests of three kinds of raw coal with different particle sizes were identified under the threshold.The results show that the recognition rate of coal is more than 93%and the recognition rate of gangue is more than 97%.The recognition effect is good and the adaptability to different coals is strongThe experimental results show that the intelligent separation system of coal and gangue based on dual-energy X-ray can identify coal and gangue effectively.It has the characteristics of environmental protection,energy saving and high efficiency.It has great practical significance to improve the technology of gangue discharging before coal preparation in coal preparation plant.Figure[32]table[21]reference[86]...