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.
