Search

This paper focuses on the risk of water inrush from the old goaf water of the upper coal group to the first mining face of the lower coal group under the condition of fully mechanized caving mining. Data from the 2101 working face of the No. 15 coal seam in the Wulihou Coal Mine were used to calculate the height of the water-conducting fracture zone on the first mining working face and the floor failure depth in the overlying No. 5 coal seam. An engineering geological model was developed, considering the lithological combination of the upper and lower coal groups, as well as the geological and hydrogeological conditions. Numerical simulations were conducted to analyse the deformation and failure characteristics of the roof and floor after dual-seam mining. The results revealed a floor damage depth of 12 m and a water-conducting fracture zone height of 109 m. Field monitoring data confirmed that after mining the 2101 working face, there was no water inrush risk from the overlying old goaf water into the No. 15 coal seam through the water-conducting fracture zone. The research results provide a reference for preventing water inrush accidents in similar fully mechanized top coal caving mining under the old goaf water. [ABSTRACT FROM AUTHOR]

Recently, deep coal mining has posed a significant challenge owing to the threat of water inrush from highly pressured aquifers in the floor strata. Water inrush in the floor strata is often associated with the structural characteristics of the underlying fault zones. The permeability of these fault zones is a critical factor in determining their potential as conduits for water flow. The variation in permeability is attributed to the varying cementation degree across different locations within the fault zones. Hence, this study is based on the key stratum theory and introduces the concept of a water-blocking key stratum within fault zones. This research focuses on the engineering context of the 16th coal seam above the lower coal seam in the 10603 working face of the Yangcun Coal Mine's tenth mining area. The study investigates the activation characteristics of the 10605F5 reverse fault zone, which cuts through the working face. Various methods, including test of simulation of similar materials and numerical simulations, are employed to analyse the hydraulic pressure distribution and the impact of mining activities on the water-blocking key stratum within the 10605F5 reverse fault zone. The research findings will provide valuable insights for preventing fault activation and water inrush. [ABSTRACT FROM AUTHOR]

Surface chemical modification allows for the rational construction of biochar with desirable structures and functionalities for environment purification. Fruit-peel-derived adsorbing material has been well studied in the adsorption of heavy-metal removal due to its abundance and non-toxicity, but its precise mechanism in removing chromium-containing pollutants remains unclear. Herein, we explored the potential application of engineered biochar prepared from fruit waste via chemical modification to remove chromium (Cr) from an aqueous solution. By synthesizing two types of agricultural residue-derived adsorbents, including pomegranate peel adsorbent (PG) and its modified product, pomegranate-peel-derived biochar (PG-B), via chemical and thermal decomposition methods, we elucidated the adsorption property of Cr(VI) on the studied materials and identified the cation retention mechanism of the adsorption process. Batch experiments and varied characterizations demonstrated that superior activity was exhibited in PG-B, which can contribute to the porous surfaces caused by pyrolysis and effective active sites resulting from alkalization. The highest Cr(VI) adsorption capacity is obtained at pH 4, a dosage of 6.25 g L−1, and a contact time of 30 min. The maximum adsorption efficiency of 90.50% in a short period (30 min) was obtained on PG-B, while PG reached a removal performance of 78.01% at 60 min. The results from kinetic and isotherm models suggested that monolayer chemisorption dominated the adsorption process. The Langmuir maximum adsorption capacity is 16.23 mg g−1. This study shortened the adsorption equilibrium time of pomegranate-based biosorbents and presents positive significance in designing and optimizing waste fruit-peel-derived adsorption materials for water purification. [ABSTRACT FROM AUTHOR]

Recently, alkaline direct methanol fuel cells have made great progress with the development of alkaline electrocatalysis, and a wide variety of catalysts have been explored for methanol oxidation reaction (MOR)and oxygen reduction reaction (ORR). However, the slow kinetics of the MOR and ORR remain a great challenge. In this paper, self-supported defect-rich AuCu was obtained by a convenient one-pot strategy. Self-supported AuCu presented a branched, porous nanostructure. The nanobranch consisted of several 13 nm skeletons, which connected in the kink of the structure. Different growth directions co-existed at the kink, and the twin boundaries and dislocations as defects were observed. When the Au-based nanostructure functioned as an electrocatalyst, it showed robust MOR and ORR performance. For the MOR, the forward peak current was 2.68 times greater than that of Au/C; for the ORR, the activity was close to that of Pt/C and significantly better than that of Au/C. In addition, it possessed superior electrochemical stability for MOR and ORR. Finally, an in-depth exploration of the impact of surface defects and electrochemical Cu removal on MOR and ORR activity was carried out to explain the MOR and ORR's catalytic performance. [ABSTRACT FROM AUTHOR]