Yichun Tao

China faces a challenge in the sustainable development of the coal industry due to pneumoconiosis problems. Dust control technologies are crucial for safe production and miners’ health, ensuring the industry’s longevity. This article reviews the development process of dust prevention and control in underground coal mines in China, summarizes various technologies, and divides them into dust suppression, open-space dust reduction, and mine dust collectors according to different stages and environments of use. In dust suppression technologies, coal-seam water injection can reduce total dust generation by 60%, wet rock drilling can reduce drilling dust in the presence of stable water sources and high-pressure bearing equipment, and water-seal blasting can reduce blasting dust by 50–70%. In open-space dust reduction technologies, spray dust suppression can remove total dust by 50–95% and the removal efficiencies of foam dedusting for total and respirable dust are reported to reach 95% and 85% under the right conditions, respectively. In dust collector technologies, dry collectors can remove 80–95% of total dust. Wet collectors achieve up to 90% efficiency, dependent on water supply and waste processing. This article also discusses vapor heterogeneous condensation technology as a promising method for improving respirable dust removal in humid mine environments.

As the basic guarantee for power distribution, navigation control, motion control and underwater operation of ROV, power transmission system provides energy security for ROV. Reasonable power transmission system design is an important guarantee for ROV comprehensive performance. In the design of the power transmission system, the high-voltage and power-frequency transmission has the characteristics of small transmission current but large volume of underwater transformer. The medium-voltage and medium-frequency transmission has the characteristics of small volume but low transmission efficiency of the underwater transformer. In order to reduce the energy loss caused by the long-distance transmission of medium-voltage and medium-frequency power electricity in the armored cable, reduce the volume of the underwater transformer, and solve the conflict between the efficiency and the volume, this paper presents an ROV power transmission method based on matrix transformation. This method conducts the long-distance transmission in the armored cable by the high-voltage and power-frequency method so as to reduce transmission loss. By increasing the transmission frequency in the underwater end, the volume of the underwater transformer is reduced under the condition of ensuring the transmission efficiency. In this way, the space occupied by the transformer on the ROV can be reduced to meet the application requirements of the ROV underwater transformer device with small volume, high power and efficient transmission.

Abstract Much dust is generated in coal mining underground work processes, posing threats to workers’ health and safety production. Dust enters the human body mainly through inhalation, which is primarily determined by the dust concentration around workers. In this study, the airflow field and dust distribution in the tunnel are simulated by Fluent software. The breathing zone for a worker was defined to clarify the extent of external dust distribution influencing dust inhalation. The effects of human respiration, dust production rates, air supply velocities, and workers’ positions on dust concentration in the breathing zone were investigated. The results show that there is upward airflow around the worker standing in the center of the air circulation. Human inhalation and exhalation barely influence the airflow distribution and respirable dust concentrations in the breathing zone. Reducing the dust production rate in the tunnel can reduce the respirable dust concentration in the breathing zone by almost the same proportion. While increasing the air supply velocity by 50% would reduce only 20% dust in the breathing zone. The dust concentrations vary along the roadway, in which the low concentration zone is located in the middle, more than 1.0 m away from the dust-producing surface and the wind surface.