# Study on Airflow Field Distribution and Dust Distribution Characteristics at Blast Piles
## 1 Introduction  
The various stages of open-pit coal mining operations are all conducted directly on the surface where dust is generated in the atmosphere and dispersed by air currents, resulting in a far greater impact radius compared to underground mining [1; 2; 3]. Among these operations, blasting produces a significantly higher amount of dust than others, with a considerable portion of the dust embedded in the blast piles. Under the influence of natural wind and shoveling operations, this dust can be re-suspended, causing secondary dust emissions [4; 5; 6]. The hazards of dust are immense, posing significant risks to both human health and the environment. It can trigger a range of respiratory diseases and pneumconiosis while contaminating mining areas and their surroundings [7; 8]. Fine dust particles, which are difficult to settle, can even be carried by the wind over hundreds of kilometers, reaching urban areas and contributing to smoggy weather. Furthermore, dust, as a suspended solid particulate, can accumulate on coal mining machinery over time, leading to equipment wear, shortened equipment lifespan, increased mining costs, and reduced production efficiency [9; 10]. The prevalence of dust in mining areas also reduces visibility, affecting the normal progress of mining operations [11; 12; 13]. Open-pit mining operations not only contaminate the atmospheric environment of mining areas but also severely jeopardize the physical and mental health of workers, ultimately leading to a decrease in labor productivity and economic benefits [1; 4]. Figure 1 illustrates the number of occupational diseases and pneumoconiosis cases over a decade from 2012 to 2021 [14]. While the annual incidence of occupational diseases has been declining since 2016, the proportion of pneumoconiosis cases among them remains high, accounting for over 75%. This underscores the fact that pneumoconiosis continues to be the primary type of occupational disease. Blast piles represent a secondary source of dust, where natural wind or shoveling operations can re-suspend dust, causing widespread dust pollution within mining areas. However, current research on open-pit coal mines primarily focuses on enhancing production techniques, improving efficiency, and preventing dust during blasting operations, with relatively limited attention given to dust originating from blast piles. Moreover, understanding the dust generation mechanisms in open-pit mines is fundamental to the precise prevention and control of dust pollution. Given the abundance of open-pit mines abroad, related research has been conducted earlier. Many foreign scholars initially focused on the movement processes of particles, including surface creep for larger particles, saltation for intermediate-sized particles, and suspension for smaller particles [15; 16; 17]. Since the 1970s, foreign researchers have quantitatively studied the emission factors of suspended particles during unloading operations to determine their environmental impact. [PERSON] [18] proposed a formula for calculating dust emissions from loading and unloading operations through field tests and experiments. [PERSON] et al. [19] derived a formula for estimating dust generation from coal piles through wind tunnel experiments, indicating that dust generation is related to factors such as wind speed, particle moisture content, coal pile surface area, and coal pile density. [PERSON] [20] conducted experiments with eight different bituminous coal samples and found that coal rank has distinct relationships with coal product size and dust quantity. As coal rank increases, the amount of coal product powder less than 250 \(\upmu\)m increases, while the mass percentage of total dust and respirable dust released from these finer coal particles decreases. [PERSON] [21] identified three primary sources of dust in open-pit mines: drilling, crushing, and transportation. Among these, crushing was found to be the largest contributor, and dust concentrations vary across different operational stages.