Rescues from building collapse accidents present a significant challenge for China's emergency rescue system. However, there are also many risk factors in a training scenario, which have been ...summarized in this study. A hierarchical indicator system for personnel safety was established, including 12 first-level indicators and 23s-level indicators. Then, an improved Grey-DEMATEL-ISM-MICMAC evaluation model was constructed to evaluate the level of risk. Influencing factor scores were determined according to the responses from the questionnaire survey. The influencing degree, influenced degree, centrality, and causality were identified, and the importance, relevance, and clustering of the various factors were obtained after making quantitative calculations. The results showed that the order of priority for solving the essential issues was safety education (A
), operating standards and proficiency (A
), equipment inspection (A
), equipment warehousing maintenance and records (A
). The solving of safety education was identified to be the most essential priority. The priority control order of direct causes was Scientific design and construction (A
), Potential fixed hazards in the facility (A
), Physical fitness of personnel (A
), Weather influences (A
), and Initiation efficiency of emergency plans (A
), and direct control measures for these five factors could achieve a relatively significant effect.
•This study studied the colloid components of fire prevention material for coalmines.•A colloid recipe was determined considering the cost, environment and technique.•An optimum proportion was ...obtained by orthogonal tests.•The new material has better performance compared with other four typical materials.•Field test indicates the colloid component is highly effective in fire prevention.
Because the existing fire prevention and extinguishing materials for coal mining cannot adhere to coal for long periods of time, this study investigated their colloid components. A colloid recipe of sodium silicate as the base material, sodium bicarbonate as the coagulation accelerator and sodium polyacrylate as the polymer additive was determined. An optimum proportion was obtained by orthogonal tests, whereby the ratio of water to solid was 4:1, sodium silicate accounted for 4%, sodium bicarbonate accounted for 5% and sodium polyacrylate accounted for 0.75‰. Comparing the performance of four other typical materials of fire prevention and extinguishing through contrast experiments, we observed that the new material has advantages of dropping the temperature, lowering the concentration of oxygen and carbon monoxide and increasing the concentration of carbon dioxide. In addition, a field test was conducted with the new material. After injection, three zones of spontaneous combustion showed clear changes: the oxidation temperature rise zone was ahead by 8m, its length was shortened by 20m and the choking zone moved up by 28m. These changes indicated the improvement of colloid could significantly increase the effect of fire prevention and extinguishing materials.
The membrane biofilm reactor (MBfR) is a novel wastewater treatment technology, garnering attention due to its high gas utilization rate and effective pollutant removal capability. This paper ...outlines the working mechanism, advantages, and disadvantages of MBfR, and the denitrification pathways, assessing the efficacy of MBfR in removing oxidized pollutants (sulfate (SO
), perchlorate (ClO
)), heavy metal ions (chromates (Cr(VI)), selenates (Se(VI))), and organic pollutants (tetracycline (TC), p-chloronitrobenzene (p-CNB)), and delves into the role of related microorganisms. Specifically, through the addition of nitrates (NO
), this paper analyzes its impact on the removal efficiency of other pollutants and explores the changes in microbial communities. The results of the study show that NO
inhibits the removal of other pollutants (oxidizing pollutants, heavy metal ions and organic pollutants), etc., in the simultaneous removal of multiple pollutants by MBfR.
Membrane bioreactor (MBR) is an efficient wastewater treatment technology, which is produced by combining membrane treatment technology and biological treatment technology, and has the ...characteristics of stable water quality and shock load resistance, and has been widely used in domestic wastewater treatment. Anaerobic ammonia oxidation (ANAMMOX) is a new type of biological denitrification technology with the advantages of low energy consumption, low oxygen demand, carbon source saving and good economic benefits. This paper introduces the principle and characteristics of the MBR nitrification-anaerobic ammonia oxidation reactor process analysis process. Prospects of anaerobic ammonia oxidation technology in MBR are foreseen.
Due to the special structures and geographical environments of the main transport roadway of underground coal mines, it is difficult to deal with accidents and rescues in cases of fire and it is easy ...to cause casualties and structural damage of the roadway. In this study, a roadway fire model was established using FDS software on the basis of theoretical analysis. The smoke diffusion, temperature distribution, and CO concentration distribution in a fire period were simulated under four working conditions. The results showed that the time required for the smoke layer to descend to human breathing height was positively correlated with the distance between the position and the fire source. Under the most unfavorable conditions, the smoke reached human breathing height at 15.11 s and 100 m away from the fire source. After the fire broke out, the ambient temperature in the roadway rose rapidly, and the highest temperature in the area adjacent to the fire source reached 340 °C. The farther away from the fire source, the lower the temperature, but it was still higher than the human body's optimum temperature (25 °C) until 200 m away. The results of this study can provide a basis for the preparation of roadway fire emergency plans.
Eco-friendly waste utilization helps in the development of sustainable infrastructures. Recently, researchers have focused on the production of road infrastructures using the circular economy concept ...of human safety. The objective of this study is to investigate and explore the utilization of optimum polymer waste content for the development of polymer-modified asphalt mixtures using response surface methodology (RSM). RSM based on Box–Behnken design (BBD) was employed to optimize experimental design and included three factors: X1, polymer type; X2, polymer contents; and X3, testing day. The optimized responses determined by the RSM were as follows: MS of 42.98 kN, MF of 5.08 mm, and MQ of 8.66 kN/mm, indicating a favorable and consistent precision in comparison with experimental values. Moreover, the Marshall characteristics of samples prepared with PE were quite improved compared to PET. In conclusion, the incorporation of such polymer wastes in road construction is a sustainable and cost-effective way of improving their engineering properties. This study will help in the development of sustainable road infrastructures supporting human safety and environmentally friendly practices.
Slope stability of open pit mines has been a hot issue of economic and safety concern. In order to reduce the accidental casualties caused by slope instability, targeted reinforcement solutions ...should be proposed for them. In this paper, GeoStudio and FLAC3D software were used to model the slope an open pit mine. The safety factors of the slope under natural, rainfall and seismic conditions are analyzed in turn. Additionally, the safety factors derived from different algorithms are compared to mutually verify the reliability of the slope stability analysis. Two sets of reinforcement design solutions—anchor rod and anti-slip pile—are proposed. Then, the two solutions are optimized so that the safety factors of the slope under three conditions reach 1.3, 1.2 and 1.1, respectively, and the optimal solution is selected from the two solutions by combining the economic benefits. The results show that the optimized anchor and anti-slide pile reinforcement solutions result in the safety factors of the slope under different conditions, reaching 1.441, 1.258, and 1.324 and 1.4, 1.238, and 1.23, respectively. The anti-slide pile reinforcement solution is more economical than the anchor reinforcement solution, so it is recommended that the anti-slide pile reinforcement solution should be chosen as the final solution.
Experimental study on methane dissolved in surfactant-alkane system Huang, Zhian; Chen, Mingli; Wang, Jingjing ...
International Journal of Mining Science and Technology/International journal of mining science and technology,
11/2020, Letnik:
30, Številka:
6
Journal Article
Recenzirano
Odprti dostop
A surfactant-polyalkane system is investigated using chemical reagents to dissolve methane and control coal seam gas from low-energy, high-efficiency, safety, and environmental protection ...perspectives. At different temperatures and pressures, a high-temperature and high-pressure reactor, gas chromatograph, and other related experimental equipment were used to perform methane dissolution experiments, and a single surfactant sodium oleate (NaOA) and n-hexane demonstrated superior results. The single-factor experiments of temperature, pressure, and NaOA addition were performed and fitted via a response surface analysis. The optimal conditions for methane solubility were as follows: temperature of 34 °C, pressure of 4.5 MPa, NaOA addition of 85 g/L, and time of 1 h. The optimal effect of the surfactant-polyalkane system in dissolving methane was achieved with 32.31 mL/100 mL. Meanwhile, the change in the surface structure of coal before and after washing with the system was compared using scanning electron microscopy. The results indicated that the gas after washing with the surfactant-polyalkane system dissolved, and the surface pore structure of the coal changed. Moreover, the specific surface area and pore size of the coal surface increased after washing. Hence, the desorption of gas from the coal surface into the system becomes easy, thereby reducing the gas content in the coal sample.
Both the macroscopic reaction and microscopic characterization of water-immersed coal have been studied. The methods of thermogravimetric analysis via Fourier transform infrared spectroscopy ...(TG-FTIR) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) are used. The apparent activation energy of water-immersed coal was significantly lower than that of raw coal. For the same coal sample, the production of CO in water-immersed coal is significantly higher than that in raw coal. The analysis shows that after water immersion, the content of hydroxyl and aromatic hydrocarbons in the coal increases significantly and the temperature at which fat-based and oxygen-containing functional groups participate in the reaction decreases. This indicates that the functional groups are unstable after water immersion and react violently. When the immersion time is 60 days, the activation energy is the lowest, the production of CO reaches its maximum, and the variation of each functional group is most obvious.
The catalytic partial oxidation of methane (CPOM) to methanol has been regarded as a promising approach for methane utilization, despite that the conversion remains a formidable challenge in the ...perspective of catalysts. A novel catalyst system of multi-wall carbon nanotubes (MWCNTs) that supported Fe2O3 with existing I2, consisting of non-noble metal and working in weak acid at an ambient temperature, was investigated for CPOM. MWCNTs supported the Fe2O3 catalyst, which was prepared by the impregnation method and characterized via HRTEM, XRD, XPS, FT-IR, and BET techniques. The characterization results reveal that, as a non-noble metal catalyst, the Fe2O3/MWCNTs catalyst had a good catalytic performance and stability in the CPOM. With the variation of reaction pressure and the dosage of Fe2O3/MWCNTs, the catalyst system obtained the highest methane conversion rate of 7.41% and methanol selectivity of 86.3%, which is analogous to that of the equivalently strong acid catalyst system. The I2-Fe2O3/MWCNTs catalyst system has great potential in the application of CPOM under mild, environmentally benign conditions, such as non-noble metal requirement, ambient temperature, and weak acid. The reaction mechanism was discussed.
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