# Study on the Particle Surface Fractal Characteristics of
## 1 Introduction  
A large amount of dusts are produced from mining, metal smelting and other production activities. Dust pollution is one of the world's public hazards. With the development of the mining industry in China, especially the improvement of mechanization in mining, dust pollution is becoming a serious problem [1; 2; 3; 4]. Workers who are exposed to high dust concentrations for an extended length of time run a serious risk to their health and safety [5; 6; 7; 8]. China reported more than 1,012,000 cases of occupational diseases by the end of 2020, with pneumoconiosis making up over 88.6% of these cases. The status of occupational sickness in China is still dire, and pneumoconiosis is still the most dangerous occupational disease, despite the fact that many production businesses have adopted numerous effective dust protection measures. It was put forward by [PERSON], [PERSON], [PERSON] et al. [9; 10; 11; 12] that sulfide ore dust is very representative in metal and nonmetal mines; it is characterized by complicated composition, hydrophobic nature and causing large and widespread damage. Sulfide ore dust, especially at the micron-level, is present in high concentrations at production sites and difficult to remove, causing widespread dust pollution and occupational hazards Therefore, it has very important meaning and practical value for sulfide ore dust research. At present, dust pollution has caused serious damageto the environment, production and life. To solve the problem of microparticle pollution, it is necessary to study the interaction mechanism of adhesion between microparticles and interfaces, so that the adhesion effect between microparticles and interfaces can be effectively controlled or utilized. The surface adhesion problem is a comprehensive subject involving physics, chemistry, biology and mechanics. The magnitude of the adhesion force between dust microparticles and the interface can measure the difficulty of dust being removed. To study the magnitude of the adhesion force, it is particularly important to study the geometric fractal shape of the dust microparticles.  
It is well known that the geometry of particles is one of the most important parameters to describe their geometric features [13; 14; 15]. For non-cohesive soil (sand, silt), particle shape has a close relation with its mechanical properties such as compressibility and filling property [16; 17]. Recent studies show that the fractal geometry theory, which was proposed and developed by [PERSON] and [PERSON] [18; 19], provides a strong tool to describe the heterogenization of natural particulates (such as rock particles, soil particles, proteins, floes and catalyst particles). Based on the fractal geometry theory, many intensive studies on the testing method of the fractal dimension [20; 21; 22; 23; 24; 25; 26] have been carried out by domestic and foreign scholars. Dust control in metal and nonmetal mines is very important. Currently, many research works about sulfide ore particles mainly focus on spontaneous combustion tendency [27; 28; 29; 30; 31; 32], but less work has considered the particle shape fractal of sulfide ores.  
In this work, based on the area-perimeter method, the shape fractal characteristics of sulfide ore particles were analyzed and summed up, providing a new approach for studying the adhesive force between particles. By combining with numerical calculation and the fractal geometry theory, the experimental result was identified and explained, revealing that the fractal dimension of sulfide ore particles can serve as an important indicator of their particle shape distribution characteristics. Simultaneously, this provides valuable information for further studying the relevant physical and chemical properties of sulfide ore particles and establishes a new theoretical method and foundation for the adhesion and removal of sulfide ore dust.