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Supplemental material, sj-docx-1-pie-10.1177_09544089211031116 for Investigation on dust dispersion during support movement in a fully mechanized mining face and the technology with support frame enclosure dust control by Jinming Mo, Wei Ma, Dandan Li and Sheji Zhang in Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering

A fully mechanized mining face is characterized by serious dust pollution and dust is a major cause of pneumoconiosis that haunts numerous miners. For a fully mechanized face having large mining heights, the main dust source in the pavement area is produced by the moving support frame. To reduce the amount of dust during support's movement, the distribution and dissipation of dust in this process were studied by combining numerical simulations with underground measurements. The results showed that with an increase of the distance from the air inlet, the wind speed of the sidewalk in the fully mechanized face first increased, then decreased, and finally increased again. At the position of the coal cutter, the highest wind speed was 1.78 m/s and the average wind speed of the roadway was about 0.8 m/s. The dust concentration at the dust source was >1000 mg/m3. An area with a high dust concentration and having a length of 15 m was formed on the rooftop, together with a 50 m long dust belt with a dust concentration of 300 to 450 mg/m3 in the pavement area of 10 m from the dust source. Beyond the 45 m radius from the dust source, the dust concentration was stable at about 250 mg/m3. Based on the dust production characteristics of the support frame, an enclosed dust-guiding device was designed and structure-optimized. Based on the on-site field application test results, it was found that the device has a satisfactory dust-guiding effect during support movement and the dust suppression rate near the dust source reached 94.8%.

To solve the problem of dust production by the caving coal seam on the weather side of a fully mechanized coal face with a large mining height, this study proposes coal cutter onboard dust removal technology for the first time. In this work, taking the 12511 fully mechanized coal face of the Bulianta Coal Mine with a large mining height as an example, a mathematical model was built to study the influence of the onboard dust collector on airflow–dust dispersion pollution and the key technological parameters of the dust collector, and field tests were performed for verification. The results of numerical simulation showed that the dust-carrying airflow, after being blocked by the coal cutter, dispersed in the lateral direction, leading to an increase of airflow velocity on the walkway side to 1.75 m s−1, and a dust concentration as high as 2500 mg m−3. At the same time, an airflow vortex area with the largest diameter of 3 m was formed near the surface of the coal cutter body, which attracted dust to gather there. However, after the application of the onboard dust removal technology, the lateral dispersion of dust-carrying airflow weakened, and the dust concentration on the walkway side was reduced to below 600 mg m−3. In addition, this technology also obviously reduced the influence scope of the vortex and the dust concentration area. It was also found that the installation height of the suction inlet of the dust collector and the air capacity had a large impact on the dust suppression efficiency. The optimum dust suppression efficiency was reached at an installation height of 1.15 m and air capacity of 120 m3 min−1. Field test verification demonstrated that the dust concentration on the walkway side could be reduced by as much as 49.3% with the application of the proposed onboard dust removal technology.

Taking the fully mechanized mining face of bulianta 12511 as the research object, the distribution law of dust movement in fully mechanized mining face with 8m large mining height was numerically simulated by using CFD software. Through the simulation results of the original dust field, it is found that the dust produced by the collapsed coal seam diffuses to the rear of the shearer under the action of wind flow, the highest point of movement of high-concentration dust mass can reach 4m, and the dust concentration gradually decreases along the roadway. High concentration dust is mainly concentrated in the 10m range before and after the shearer and on the side of the bottom plate close to the coal retaining plate, with a maximum of 3500mg/m3. In order to effectively reduce the dust in the working face, prevent dust accumulation and pollute the underground working environment, this paper innovatively proposes to install an airborne dust collector in the large mining height working face to control the dust spreading to the pedestrian side at the dust source and purify the dust. By studying the influence of dust collector placement position and treatment air volume on the dust movement and distribution rule and dust removal effect of the working face, the optimal dust removal efficiency of the working face with large mining height is obtained by the dust collector placement position and treatment air volume adaptation combination, and the maximum dust removal efficiency can reach 100%.

In order to solve the problem of dust pollution in mechanized tunneling face, Master the best matching relationship between the long and forced ventilation and the dusting and short dust removal parameters in the working face, reducing the dust concentration of working flour to the maximum degree. This paper takes the high-yield dust comprehensive mining face of Wangjialing coal mine as the research background, by establishing CFD model, the effect of dust control on different axial and radial air out ratio of working face is compared, and the parameters range of effective dust control is obtained, and the actual application of the field is verified and analyzed in order to get the best matching parameters of the control dust removal process. The results show that, after increasing the dust control of the wall winder, a fresh air flow transparent wall along the wall of the tunnel is formed in the tail of the roadheader, the dust can be controlled in the area of the front of the work. When the ratio of the axial and radial air out is 1:3, the dust is controlled in the smaller area near working face, the dust control effect is the best. The total and respirable dust concentration of the driver’s position and the 5m position at the tail of the driving machine can be reduced to less than 26.1 mg/m3 and 12.7 mg/m3. The dust control efficiency is above 80%, the overall dust efficiency is up to 94%, the dust reduction effect is obvious, and reduces the occupational hazards of workers.

Creep strain near crack front zone is one of the main driving forces in nuclear structural materials of stress corrosion crack propagation. To understand the effect of temperature variation on mechanical field near crack tip of nuclear structure material in high temperature water environment, compact tensile specimen was taken as an research object and ABAQUS finite element analysis software was also adopted, the Mise stress, plastic strain and creep strain near SCC crack tip region was studied. Results show that the area of the high-stress region decreases gradually with the increasing of the creep temperature, and its declining rate was faster and faster. The effect of temperature variation on the plastic strain is not very obvious. Temperature only has an obvious effect on a small scale near crack tip. With the increase of the distance from the crack tip, the effect of temperature on creep is gradually reduced.