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An abandoned open pit was used as a tailing pond for a concentrating mill, with the height of the water surface subject to cyclic fluctuation. e effects of drying and wetting cycles on the mechanical parameters of pit rock were tested. Interactions of the hydrochemical environment, due to the dissolution of tailings, and drying and wetting cycles caused degradation of mechanical properties in the rock. It was found that uniaxial compressive strength and elastic modulus decreased as the number of dry/wet cycles increased. e quantitative relationship between the mechanical parameters and the number of dry/wet cycles was indicated by an exponential function. In addition to uniaxial testing, cohesion and the internal friction angle were determined through triaxial testing.e shear strength index deteriorated under the drying and wetting cycles. e hydrochemical environment also negatively affected the mechanical parameters. Potential effects between drying and wetting cycles and slope displacement were analyzed by on-site monitoring.e results show that the displacement increased because of the drying and wetting cycles, which may lead to sudden failure of the slope.

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The possible role of bioaerosols in the transmission of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) causing the coronavirus disease 2019 (COVID-19) has recently been highlighted. A bioaerosol can be comprised of bacterial cells, fungal spores and viruses. Aerosolized fungal spores in indoor environments can cause adverse health effects. As a colony propagates from the center to the perimeter, the age of fungal spores and thus the adhesion force to the colony can be much different. The spore detachment may vary according to the growing position of the spores on a colony in relation to the airflow. This study investigated the aerosolization of fungal spores at different positions of a colony. A fungal colony was divided into a quantity of sub colonies according to the age distribution. Each sub colony was subjected to airflow in a wind tunnel to determine the released spores by two count methods. The results revealed that the initial spore density, the spore release rate, and the spore release proportion for the central sub colony were all significantly higher than that for the sub colony at the edge. The spore release rate for the central sub colony was approximately 2.6 times that at the edge. Spores growing at the center of the colony were aerosolized more easily than that growing at the outer edge. Growth age is a significant factor in the difference of spore aerosolization between sub colonies.

Heat damage in deep mines is severe and can lead to adverse health effects. The existing refrigeration schemes for the heading face in excavation roadways aim to cool the whole cooling region. However, the ratio of the area occupied by workers to that of the cooling region is quite small. A great quantity of energy for refrigeration is doomed to waste. In this study, a new cooling strategy for building a non-uniform environment in the heading face was developed. A certain quantity of well-designed tracking air coolers were distributed in the excavation roadway near the heading face. The air cooler tracked the constantly moving workers and blew cold air to them. Economic analysis based on estimation of the cooling load for this cooling strategy was conducted. The airflow in the excavation roadway was numerically simulated to estimate the cooling effect. An average energy saving of approximately 30% could be realized. The thermal environment for the workers whether near the heading face or in the roadway improved. This cooling strategy should be considered in all of mine cooling.

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