In order to address the issue of high temperatures and thermal damages in deep mines, the factors causing downhole heat damage at high temperatures were analyzed, the mine ventilation system was optimized and rebuilt, and a cooling system was established. The proposed cooling system uses mine water as the cooling source, and its features are based on the analysis of traditional cooling systems. The current ventilation system in the 1118 m deep pit of the Jinqu Gold Mine was evaluated, and the ventilation network, ventilation equipment, and ventilation structures near the underground working face were optimized. The low-temperature mine water stored in the middle section of the mine at 640 m depth was used as the cooling source, and a cooling system was established near the 440 m deep middle return well to alleviate the high-temperature and high-humidity conditions of the 280 m deep middle-western area. The results show that the effective air volume in the west wing at 280 m was 3.0 m3/s, the operating ambient temperature was 27.6°C, the relative humidity was reduced to 76%, and the temperature was reduced by 5-6°C after the optimization of the system.
How
to build a satisfactory indoor environment has become increasingly
important. In this paper, the synthesis and improvement of the most
widely used polyester materials in China were carried out based on
two different preparation methods, and the structures and filtration
performances were tested and analyzed. The results showed that a carbon
black coating was wrapped on the surfaces of the new synthetic polyester
filter fibers. Compared with the original materials, the filtration
efficiencies of PM10, PM2.5, and PM1 were increased by 0.88–6.26, 1.68–8.78, and 0.42–4.84%,
respectively. The best filtration velocity was 1.1 m/s, and the new
synthetic polyester materials with direct impregnation demonstrated
superior filtration performance. The filtration efficiency of the
new synthetic polyester materials was improved on the particulates
with sizes of 1.0–5.0 μm. The filtration performance
of G4 was better than that of G3. The filtration efficiencies of PM10, PM2.5, and PM1 were improved by 4.89,
4.20, and 11.69%, respectively. The quality factor value can be used
to assess the comprehensive filtration performance of air filters
in practical applications. It could provide reference values for the
selection of synthetic methods of new filter materials.
Dynamic ventilation control based on the concept of thermal comfort is proposed and applied to single head roadway in high-altitude gold mine in Qinghai. Hourly thermal comfort values are determined for typical working conditions, and a thermal comfort curve is generated. The values are adjusted based on the external environment and the changes in the miners’ thermal comfort. The Fluent software is used to simulate the temperature field and wind speed field of the tunnel roadway at three heights, and the results are used to fit the thermal comfort curve in the roadway. The results show that the thermal comfort is lowest at a roadway height of 1 m and a longitudinal length of 16 m because the wind speed is the highest and the temperature is lowest at these locations. When the dynamic ventilation control is used, the optimal thermal comfort levels can be determined for the locations in the single head roadway.
With the increase in global environmental pollution, it is important to understand the concentration characteristics and correlations with other pollutants of atmospheric particulate matter as affected by relevant policies. The data presented in this paper were obtained at monitoring stations in Xi’an, China, in the years from 2016 to 2020, and the spatial distribution characteristics of the mass and quantity concentrations of particulate matter in the atmosphere, as well as its correlation with other pollutants, were analyzed in depth. The results showed that the annual average concentrations of PM10 and PM2.5 decreased year by year from 2016 to 2020. The annual concentrations of PM2.5 decreased by 20.3 μg/m3, and the annual concentrations of PM10 decreased by 47.3 μg/m3. The days with concentrations of PM10 exceeding the standards decreased by 82 days, with a decrease of 66.7%. The days with concentrations of PM2.5 exceeding the standards decreased by 40 days, with a decrease of 35.4%. The concentration values of PM10 and PM2.5 were roughly consistent with the monthly and daily trends. The change in monthly concentrations was U-shaped, and the change in daily concentrations showed a double-peak behavior. The highest concentrations of particulate matter appeared at about 8:00~9:00 am and 11:00 pm, and they were greatly affected by human activity. The proportion of particles of 0~1.0 μm decreased by 1.94%, and the proportion of particles of 0~2.5 μm decreased by 2.00% from 2016 to 2020. A multivariate linear regression model to calculate the concentrations of the pollutants was established. This study provides a reference for the comprehensive analysis and control of air pollutants in Xi’an and even worldwide.
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