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The large size shearer drum in the large mining height working face generates more obvious turbulent wind in cutting the coal body, which causes the local wind speed of the working face to change, and the horizontal diffusion of dust particles to the sidewalk area. In order to clarify the influence mechanism of cutting turbulent wind on the dust mass concentration distribution along the working face with large mining height, a coupled mathematical model of airflow and dust was constructed by numerical simulation method for 85219 working face, and the airflow distribution, dust migration and dust mass concentration distribution at the height of the breathing zone were studied. The results show that, compared with the flow field under system ventilation only, the partial velocity of negative drift increases significantly at the front and back of the drum and at the moving frame, and a “wind drift zone” with negative drift wind velocity value of -1.06 m/s is generated near the drum. Under the disturbance of cutting turbulent wind, dust masses with a mass concentration of more than 151.85 mg /m3 at the front and back rollers have transverse dispersion to the sidewalk area. In the state of downwind coal cutting, the ability of cutting turbulent wind at the front rollers to induce transverse dispersion of cutting coal dust is higher than that at the back rollers. The dust mass concentration in the breathing zone of the sidewalk near the front roller was increased by 64.77% compared with the condition of system ventilation only. The comparison between the simulated data and the field-measured data shows that the relative error is less than 12.57%, and the simulated data is relatively accurate. Based on this, a dust-bearing air flow dust control device shearer is proposed, which is applied in the field and its dust control effect is tested. The dust removal efficiency in the working area of the working face is more than 78.31%, and the total dust removal efficiency is more than 89.93%.

In order to obtain the dust distribution law in the fully mechanized coal face, the distribution of shearer cutting dust and the dust along the working face was studied by numerical simulation and field measurement respectively. The results show that when the shearer cuts coal downwind, along the direction of the air flow from the rear drum to the front drum area, the dust concentration keeps rising, and the diffusion caused by the air flow has an obvious effect on the increase of dust concentration. When the shearer cuts coal upwind, the dust concentration along the road shows an increasing trend, and the dust concentration in the dust source area changes rapidly. The dust produced by the drum plays a leading role in the dust pollution of the working face. The change trend of dust concentration in the groove of scraper conveying machine is basically the same as that in the support walkway, but the latter lags behind relatively, and the dust concentration is relatively low. Therefore, when taking measures to prevent dust, downwind coal cutting should focus on the influence of air flow, while upwind coal cutting is mainly aimed at the dust production of the drum itself, but under any conditions, cutting dust production is the main source of dust on the working face.

In order to obtain the dust distribution of PM5 and PM10 in large mining height fully-mechanized face, the dust concentration around the shearer drum and along the downwind side of the shearer are measured under the conditions of the following wind and upwind respectively. The results show that when coal is cut in following wind, the initial concentration of PM5 and PM10 dust around the rear drum is high, then gradually decreases and becomes stable. The concentration of the front drum is low at first, and rises sharply after 70 to 80 s. When coal is cut in upwind, the initial concentration of the front drum fluctuates greatly, and the concentration of the rear drum rises about 10 s earlier than that in following wind. When coal is cut in following wind, the PM5, PM10 and total coal dust concentration reach the highest at the downwind of shearer around 10 m, then gradually reduce and tend to be stable at 40 m. The PM5 proportion is higher at first, and falls to the lowest at about 15 m, then rises again under the effect of wind. The PM10 proportion is on the decline overall. When coal is cut in upwind, the dust concentration reaches the highest at the downwind of shearer 6 m or so, and is stable about 20 m. PM5 accounts for 60% to 80%, while PM10 accounts for 65% to 95% under both conditions.

To study the distribution pattern of drug dust in the antibiotic raw material drug powder screening workshop and improve the working environment, we used COMSOL Multiphysics 6.0 software to simulate and study the airflow distribution and dust transport law in the powder screening workshop. The results indicated that the dust in the powder screening workshop diffused rapidly with the airflow and reached a stable state at the 100th second. After the dust migrated to a stable state, the area with excessive dust concentration (dust concentration>6 mg/m(3)) widely distributed, mainly distributed in the middle and lower parts of the wall opposite the air inlet from the rotary vibrating screen. The distribution of dust showed a characteristic of local aggregation, and dust transport was related to airflow movement, which was prone to aggregation in areas with low airflow velocity and eddy currents. On the plane of the human respiratory belt height (h=1.5 m), the concentration near the dust producing surface was high, with local concentrations exceeding 32 mg/m(3). It was the key area for dust prevention and control. And the working environment can be improved by changing the air flow distribution in the workshop or other dust reduction methods.

At present, the fact that the airflow of the air duct outlet in fully mechanized heading face cannot be adjusted and cannot meet the practical requirement of ventilation dust suppression may lead to the steep rise of safety hazard and pollution risk. While by adjusting the angle, caliber, and the distance from the air duct outlet to the heading face, the dust distribution can be optimized and the dust suppression efficiency can be effectively improved. The acquisition method of regulation rules under different sizes of the roadways, the angles, calibers, and distance from the air duct outlet to the heading face is investigated by using the rough set theory, finite element flow field numerical simulation and underground test verification. Then, the decision information system, the discernibility matrix algorithm for attribute reduction and the heuristic value reduction algorithm for rule acquisition are established, and the regulation rules of the outlet parameters are obtained and expressed. The dust concentration analysis after adjusting shows that the area of the dust concentration is significantly reduced and the dust reduction rate at drivers can be increased by 48% compared with the original field, which provides theoretical basis for the optimal dust distribution and dust sup pression. [ABSTRACT FROM AUTHOR]

Due to the similarity theory and the gas-solid two-phase flow equation motion, taking 11/96 belt conveyer inclined shaft in Xishimen Iron Ore as the research background, author educed the similarity index and designed a parallel model device for the specific situation in the belt convey roadway. Meanwhile, the dust distribution was experimentally studied. The results indicate that dust concentration along the first rises gradually to a maximum value in the roadway model,then gradually slowed down. Airflow direction,the average velocity of wind,the operating speed of the belt, ore moisture, feeding rate and feeding height are main influencing factors of dust distribution in the belt conveyer roadway. When the belt run along the wind direction in a low speed,the higher the velocity of wind,the smaller dust concentration will be. In the same way,the higher ore moisture,the lower the dust concentration. In addition,when ore moisture reaches the value of 3.09%,the dust concentration no longer reduces; What is more, the faster the feeding rate and the higher the feeding height,the greater dust concentration will be. [ABSTRACT FROM AUTHOR]