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Spherical and flaky particles are mixed during hard rock tunneling. In particular, flakey particles are difficult to load, resulting in conveying machines that have difficultly operating efficiently. Based on the characteristics of flakey particles and the present conveying structures, such as star wheels, three new conveying structures are introduced in this paper, and the parameters related to the conveying ability are evaluated with theoretical analysis. Then, the flow and trajectory of particles under different conveying structures and the difference in their working capabilities were investigated with the help of the discrete element method (DEM). Finally, conveying machines with different conveying structures are made with 3D printing technology and experiments for validation of the conveying ability are performed. The results show that the conveying structures can be divided into two categories: those with a rotational speed proportional to the loading rate and those with the opposite condition. The propulsion status has a stable loading phase with a long time period relative to the non-propulsion status. The findings can be used to guide conveying machine designs, and they can be helpful for the enhancement of the working ability in conveying particles with flakey shapes. [ABSTRACT FROM AUTHOR]

The selective catalytic oxidation (SCO) is an effective method for removing slipped high-concentration ammonia from NH3-fueled engine exhaust gas. Herein a novel bifunctional catalyst was synthesized by mechanically mixing sulfated Ce/ZrO2 (Ce/ZrO2-S) with a small fraction of Pt/Al2O3 (Pt 0.1 wt.%) for SCO of NH3. As expected, the introduction of a small amount of Pt/Al2O3 significantly improved NH3 conversion ability of Ce/ZrO2-S catalysts toward low-temperature direction. When the mass ratio of Pt/Al2O3 to Ce/ZrO2-S was 7.5% (the corresponding mixed catalyst was denoted as P@CZS-7.5), T90 temperature was 312 °C. More importantly, P@CZS-7.5 catalyst exhibited a much better N2 selectivity (> 96%) in a wide temperature range (320 ~ 450 °C). H2-TPR results revealed that the addition of a trace amount of Pt/Al2O3 significantly led to a distinct shift of reduction temperature peak toward low-temperature direction, thereby greatly improved the low-temperature redox performance of mixed catalysts. Furthermore, NH3-TPD and BET results showed that P@CZS-7.5 catalyst exhibited a similar NH3 adsorption capacity to Ce/ZrO2-S catalyst, while the former had a relatively higher specific surface area than the latter. It was considered as a crucial factor for P@CZS-7.5 catalyst maintaining superior N2 selectivity in high-concentration NH3 (5000 ppm) removal processes. In situ DRIFTS results indicated that P@CZS-7.5 catalyst followed the internal selective catalytic reduction (i-SCR) mechanism in NH3-SCO reactions. [ABSTRACT FROM AUTHOR]

Scraper conveyor is the most important transportation equipment in the comprehensive mining equipment, and the chain drive system is its core subsystem, its dynamic characteristics will significantly affect the efficiency of coal transportation in the comprehensive mining face. In this paper, the dynamic characteristics of chain drive system when impacted by falling coal are investigated by means of test. The impact test bench of scraper conveyor was set up to analyze the effects of chain speed, impact height and impact load mass on the dynamic characteristics of the chain drive system of scraper conveyor under the working conditions of unloaded and loaded. The results show that the longitudinal vibration of the scraper conveyor is most obvious when it is impacted by the falling coal, and the chain speed, impact height and impact load mass of the scraper conveyor all play an excitation role on the vibration of the chain drive system, and the vibration of the chain ring is the most intense in the chain drive system, and the loaded coal pile conveyed on the scraper conveyor plays an inhibiting role on the vibration of the chain drive system. This study can help to identify the location where the scraper conveyor fails first in the impact condition, so as to provide a basis for its structural design and improvement, which is of great significance for the stable operation and structural optimization of the scraper conveyor. [ABSTRACT FROM AUTHOR]

To address the lightweight and real-time issues of coal sorting detection, an intelligent detection method for coal and gangue, Our-v8, was proposed based on improved YOLOv8. Images of coal and gangue with different densities under two diverse lighting environments were collected. Then the Laplacian image enhancement algorithm was proposed to improve the training data quality, sharpening contours and boosting feature extraction; the CBAM attention mechanism was introduced to prioritize crucial features, enhancing more accurate feature extraction ability; and the EIOU loss function was added to refine box regression, further improving detection accuracy. The experimental results showed that Our-v8 for detecting coal and gangue in a halogen lamp lighting environment achieved excellent performance with a mean average precision (mAP) of 99.5%, was lightweight with FLOPs of 29.7, Param of 12.8, and a size of only 22.1 MB. Additionally, Our-v8 can provide accurate location information for coal and gangue, making it ideal for real-time coal sorting applications. [ABSTRACT FROM AUTHOR]