Research On Dust Diffusion Law In Fully Mechanized Mining Face Coal With High Humidity

With the improvement of the mechanization on the full-mechanized mining face, more and more dust is produced by the mining which makes the mining safety and environment problem get worse. The most dust productive working place is the full-mechanized mining face which produces a much higher dust density than the national sanitation standard. It not only influences the health of the workers but also jeopardizes the safety production. Therefore, it is significant to formulate effective dustproof and dust reducing measures. Among them, it would be very helpful to solve this problem by researching the law of movement for the coal dust on the coal face. This paper is focus on researching the law of the distribution and dispersion for the dust.Aiming at this problem, we have made a field test for the dust concentration on the full-mechanized mining face of the Pinggou coal mine which has a high humidity and collected the sample of the dust and analyzed the dispersion experiment for the collected example. By the field test for the dust, the actual law of regularity for change of the dust concentration on the full-mechanized mining face is as follows. The dust thrown out from the roller coal cutting place as a certain muzzle velocity disperses on-way under the wind current acting force gravity adsorption of the bottom plate and coal wall and the rebound phenomenon to the dust fall. The on-way distribution curve for the overall dust concentration appears two maximum values near the bottom plate and the coal wall. Then, with the longer migration of the dust, the on-way distribution curve for the overall dust concentration towards to a stable value; the on-way distribution curve for the overall dust concentration near the top plate and the hydraulic support only appears one maximum value and with the longer migration of the dust, the on-way distribution curve for the overall fine dust concentration towards to a stable value as well. By analytic test of the dispersion degree for the dust, the dispersion features of the different grain sizes scale for the dust are got. The dusts with particle size over 10μm mainly disperse on the full-mechanized mining face around the space near the bottom plate and the coal wall; the dusts with particle sizes less than 2μmbasically disperse equably among the whole space drifting with wind and couldn't settle easily.Based on analyzing the single fine dust particle under force carrying situation, the dispersion equation for the particle in the different situations of the wind currents is built and the relative data of the equation is determine according to the site condition. By analyzing and calculating of the dispersion equation, the influence of the wind speed to the dust dispersion on the full-mechanized mining face is as follows. When the wind speed is between 0.25 to 4m/s, it won't cause obvious secondary blowing dust. Moreover within this scope, the higher of the ventilation speed, the less on-way overall dust concentration is and distance for the overall dust concentration toward to the stable value is shorter which is because that high wind speed would prevent the dust dispersing randomly and make it exhaust from the roadway as soon as possible.