Two kinds of polyformaldehyde（POM） with different fluidity were reinforced by short glass fiber（GF）, the changes of mechanical properties of the two modified products were analyzed. The research shows that when K90coformaldehyde is used as the base material, although the reinforcement effect is more obvious, the melt index（MI）decreases more, and the processing fluidity becomes worse; K270 coformaldehyde with good fluidity is selected as the base materia, when the amount of glass fiber added is between 20%～25%, the product has good fluidity and is suitable for the development of reinforced modified products. Glass fiber has a good reinforcing effect on POM, its tensile strength was increased from 62 MPa to 120 MPa,the tensile modulus was increased from 2 599 MPa to 8 950 MPa, nearly three times higher, and the bending strength was increased from 79 MPa to 176 MPa. Moreover, the impact performance of the product is little affected by the addition of glass fiber, which can be maintained at 7.0 KJ/m~2, and the effect of reinforcement and modification is very ideal.
The traditional method of refining or purifying the crude acetaminophen is to use water as solvent to recrystallize the crude product, and the purity of the product is low. In order to obtain the finished product with higher purity, the structural formula of the unknown impurity dimer was determined by experiments. By analyzing the physical and chemical properties of its structural formula, it was judged that the unknown impurity was easily soluble in alcohol reagents. Ethanol was selected as the solvent according to the production experience, and through the investigation of the amount of activated carbon, decolorization temperature and time, the optimum production process conditions were determined: the amount of ethanol solvent added is 4 030 kg, the decolorization temperature is 81～84 ℃, the amount of activated carbon added is 60～90 kg, and the decolorization time is 30 min. The products can meet the requirements of European Pharmacopoeia EP9.
Stainless steel fiber sintered screen is the main filter material for viscose filtration in the viscose production process,which is used for primary filtration, secondary filtration and waste rubber filtration in the viscose production line.The filter screen is completely discarded after use and cannot be reused. Due to different manufacturers, the cost of each filter screen is 2 000 ～ 5 000 yuan. According to the different processes used, the service cycle of each filter screen is 30～120 d, and the consumption of filter screen has become one of the reasons for the high production cost of viscose. The process of regenerating and cleaning stainless steel fiber sintered mesh by high temperature hydrolysis technology was introduced, after improving the process, the filter screen can be reused, effectively reducing the consumption of the filter screen in viscose production, greatly reducing the production cost of viscose fiber.
With the in-depth development of the coal industry, the high-quality resources in coal mines are decreasing. In order to release coal resources as much as possible, filling mining and residual coal re-mining have become an important technical means for coal enterprises to innovate technology and extend the service life of mines. At the same time, according to the continuous change of environmental protection policy, the disposal of solid waste such as coal gangue has gradually become a problem that major coal enterprises have to face. Based on the research of coal gangue and filling materials, the preparation and use method of coal gangue high water jet filling material was put forward, which solved the problem that the two corners of the underground comprehensive mechanized gangue filling coal mining technology could not be effectively filled, and the underground old roadway and empty roadway management cost was high, difficult, and it was easy to affect the coal quality after backfilling. At the same time, it met the needs of coal mine for gangue treatment.
Water and sand inrush disasters often occur when mining under loose aquifer is limited. Especially when faults exist in thin overburden rock in working face, water and sand inrush disasters are more likely to occur, which seriously threaten mine safety production. In Yangcun mine, the Poluoshu No.2 fault runs through the whole working face diagonally,and the minimum vertical height of the coal pillar mined along the bottom is slightly greater than the minimum vertical height of the coal pillar left with sand protection. In order to ensure the safety of the working face mining, the theoretical prediction and numerical simulation methods are used. The failure height of overlaying rock and the safety of working face mining through oblique fault were analyzed, and the idea of fault grouting reinforcement to realize working face safety production was put forward. The fault grouting reinforcement scheme was designed, and the effect of grouting reinforcement was tested on the underground site. Combined with the corresponding safety technical measures, the safety mining of 330 working face is successfully completed. The research results have certain guidance and reference significance to realize the safe mining of thick unconsolidated bed and extremely thin bedrock working face under the influence of fault structure.
To explore the control effect of bolt on tensile-shear composite fracture of surrounding rock in deep roadway under different anchoring parameters, the unilateral free-face loading test was carried out on the anchor solid specimens with different anchorage parameters under the quasi-plane strain condition, and the tensile-shear fracture evolution and deformation characteristics of anchor solid under different anchorage spacing and anchorage angle were compared and analyzed. The results showed that both horizontal anchorage and inclined anchorage could effectively improve the deformation resistance of the specimen, and had a significant inhibitory effect on the deformation and failure of the specimen. Horizontal anchorage could effectively inhibit the occurrence of tensile fracture of specimens, and the inhibitory effect gradually increased with the decrease of bolt spacing within a certain range. Inclined anchorage had more obvious inhibitory effect on shear failure of specimens, and there was an optimal anchorage angle in the process of inclined anchorage. This experiment provided a theoretical reference for further research.
Hydrological monitoring under the condition of mining under pressure in coal mine is of great significance to the safety of mine production. In order to solve the problems of real-time continuous and intuitive display of hydrological monitoring, based on computer, communication and sensor technology, this paper proposed and formed an unattended coal mine hydrological monitoring integrated system suitable for underground complex environment. A data storage and analysis platform was established to realize automatic alarm of hydrological anomalies. The field application research was carried out in the mine, and good monitoring results were obtained.
In order to increase the mining efficiency and ensure the service life of the roadway, combined with the causes and current situation of roadway damage in Yangdong Mine, the deep and shallow hole combined grouting reinforcement combined with anchor net spray cable support technology and hollow anchor cable grouting construction technology were adopted to improve the overall stability of the roadway. The results showed that the experiment has achieved the expected support strength.
In order to ensure the safety of working face in the process of mining, laboratory analysis and numerical simulation were used to study the characteristics of collapse column and mining optimization in Gequan Mine. Sampling in the collapse column, laboratory analysis showed that the collapse column of Gequan Mine had the characteristics of dense internal structure, high cementation, common scratches and traction near the contact surface, and clear interface. The numerical simulation showed that the outlet water of collapse column working face was closely related to the change of ground pressure during mining. A certain width of protective coal pillar should be set for the collapse column in the working face, but after grouting reinforcement was carried out around the collapse column, the scheme of direct mining could be adopted to achieve safe production.
With the rapid development of information and intelligence, automation technology has been widely used in various industries. The coal mine industry has the characteristics of poor working environment, high labor intensity and high safety risk coefficient. The tank guide of coal mine is an important equipment connecting the ground and underground. The safety of its operation is directly related to the safety production of coal mine and the life safety of employees. Therefore,detection and maintenance are very important. Based on TRIZ innovation theory, this study designs an intelligent maintenance machine for hoisting tank guide rope in vertical shaft of coal mine. The equipment has simple structure,convenient operation and strong working stability, which reduces labor cost and improves work efficiency and quality.
Biomass is a renewable carbon-containing resource with rich reserves and low cost, which plays an important role in achieving the dual-carbon goal and energy transformation. Pyrolysis technology is an important way to convert biomass into biofuels and high value-added chemicals. The pyrolysis mechanism of biomass was reviewed, the application of molecular dynamics simulation（Reax FF） and density functional theory（DFT） calculation in the study of pyrolysis mechanism of cellulose, lignin and other biomass materials was emphatically introduced. The deficiencies and difficulties in the research of biomass pyrolysis mechanism at present were analyzed, references and ideas for the application of Reax FF simulation and DFT calculation in biomass pyrolysis were provided, and the research direction of the application of computational chemistry to biomass pyrolysis in the next stage was proposed.
This paper discussed the application of three working faces in the second mining area of Laomupo Coal Industry Corporation Ltd., Guxian County, Shanxi Province. The data interpretation adopted the geometric intersection method.According to the measured field strength analysis curve, the attenuation law of the field strength curve was compared.Combined with the known geological data of the working face, the geological abnormal area was delineated. Compared with the actual situation after mining, there was a certain error in the range of geological abnormity, and there was no underreporting of geological structure.
In order to study the impact of mining in Jiulong mine on groundwater resources, this paper used the methods of theoretical calculation, data analysis and water level observation and analysis to calculate the groundwater impact area in Jiulong mine. The maximum height of water conduction fracture zone was 64.77 m and the maximum height of caving zone was 16.02 m. It showed that under the current conditions, the mining of Jiulong Mine had a serious impact on the sandstone aquifer of the Lower Shihezi Formation, the sandstone aquifer of the large coal roof, the Yeqing limestone aquifer and the Daqing limestone aquifer, and had a slight impact on the Quaternary aquifer and the Ordovician aquifer under the coal seam.
Due to the footage of rock roadway, roadway renovation and raw coal screening, a large amount of gangue will be produced. In order to protect the environment, prevent land subsidence and protect the surface attachments and ground buildings, the gangue under Xingdong Mine does not rise to the well, and the gangue mountain is not set up on the ground. All the gangue produced in the production process is used for underground filling. In order to solve the problem of gangue treatment, the mine specially designed the gangue filling working face to ensure the gangue filling rate to meet the production demand. The existing equipment was used to redevelop the gangue filling scraper conveyor.After the upgrading and transformation, the SGZC900/400 gangue filling scraper conveyor increased the transportation capacity to 656 t/h, increased the output by 1.87 times, and ensured the monthly output requirements of Xingdong Mine.
In order to improve the effect of coal gas extraction, taking the blasting and permeability improvement of No.18204 Face in Shaping Coal Mine as the research object, the discrete element method is used to study the velocity field,stress field and fracture field under the conditions of no control hole and control hole radius of 60 mm, 80 mm and 100 mm respectively. The results show that the larger the diameter of the control hole, the greater the reflection degree of the stress wave, the greater the range of the stress concentration zone, the greater the frequency of fracture development around the control hole, the greater the degree of connectivity, and the more conducive to the fracture along the ’ blast hole-control hole-blast hole ’. On this basis, the field test of deep hole blasting antireflection in No.18204 Face was carried out. The results show that the average gas concentration of large diameter control hole and control hole with radius of 100 mm increases by 96.7%～99.3%, and good blasting antireflection effect is obtained. The research results can provide reference for blasting parameter design and scientific research of blasting antireflection operation.
Taking No. 81306 Face of Yongdingzhuang Mine as the research background, aiming at the problem of gas concentration exceeding the limit in the local area during the mining process, through the research on the gas drainage technology of high-level boreholes, Fluent software was used to establish a simulation model for the gas migration in the working face, and field tests were conducted on the working face. The results show that the application of high-level borehole gas drainage technology makes the mean value of gas drainage pure amount reach 4.06 m~3/min, the mean value of drainage concentration reach 15.9%, and the gas drainage rate reach 55.7%, which effectively reduces the gas concentration in the high gas concentration area and improves the safety factor of mine operation.
situ stress is the fundamental force that causes various engineering geological disasters. Based on the in-situ measurement of Anju Mine, some suggestions on roadway design and maintenance were put forward. The main conclusions were as follows:（1）the average maximum principal stress of the mine was 50.57 MPa, and the direction is 118.47°（E28.47° S）;（2） The mine was absolutely dominated by horizontal stress σ H ＞σ v ＞σ h type stress field, and belonged to the super-high stress region in the magnitude;（3）The average error of the vertical principal stress of the mine was not more than 6%, and the lateral pressure coefficient λ 1.15～1.41 with an average of 1.28;（4）The primary support strength of roof and floor should be strengthened for roadway support. The research results of this paper were of great significance to the safe and efficient production of coal mines.
Since 2002, Xingdong Mine of Jizhong Energy Co., Ltd. has begun to implement solid roadway filling, which opened the precedent of filling mining in China, and continuously practiced green filling mining. Through 20 years of continuous research and development and practice, the innovation and progress of filling technology, materials and equipment have been promoted, and the technical system of continuous filling mining under construction has been established. the research and development and engineering practice of the key technologies of filling mining in Xingdong Mine in the past 20 years was discussed, which had practical guiding significance for guiding the construction of ecological mines and promoting low-carbon green mining in the coal industry.
Shengli lignite and rape straw were selected as the research objects, the combustion properties of lignite, rape straw and their blends were investigated by thermogravimetric analyzer, the synergistic effect of combustion of the blends was analyzed and compared, and its kinetics was analyzed. The results showed that the blending of rape straw improved the ignition performance and comprehensive combustion performance of lignite. The synergistic effect of volatiles combustion process of blends was weak, while the synergistic effect of fixed carbon combustion process was larger, and the synergistic effect was the best when the blending ratio of rape straw was 30%. Kinetic analysis showed that the activation energy of rape straw combustion process was higher than that of lignite, especially the combustion process of fixed carbon was more obvious, however, the activation energy of the blend was between rape straw and lignite, and lower than the theoretical calculated activation energy, which further indicated that there was a synergistic effect between lignite and rape straw in the co-combustion process.
The stability of coal pillar in the process of coal mining is the key to the stability of mining roadway. The size of coal pillar is an important factor affecting the stability of coal pillar, but the large size of coal pillar will also cause the waste of coal resources. In order to determine the reasonable width of coal pillar, taking the 9110 return air roadway and auxiliary air intake roadway driving face of No.9 coal seam in Shigang Mine as the research object, the reasonable width of coal pillar in double roadway driving of 9110 working face is studied and analyzed by engineering analogy and numerical simulation method, combined with its geological and mining conditions, and the reasonable width of coal pillar is preliminarily determined, which provides technical experience for the determination of coal pillar width in No.9 coal seam and other similar working faces in Shigang Mine.
