Influence of particle size polydispersity on coal dust explosibility

Modelling Coal Dust Explosibility of Khyber Pakhtunkhwa Coal Using Random Forest Algorithm

Coal dust explosion constitutes a significant hazard in underground coal mines, coal power plants and other industries utilising coal as fuel. Knowledge of the explosion mechanism and the factors causing coal explosions is essential to investigate for the identification of the controlling factors for preventing coal dust explosions and improving safety conditions. However, the underlying mechanism involved in coal dust explosions is rarely studied under Artificial Intelligence (AI) based modelling. Coal from three different regions of Khyber Pakhtunkhwa, Pakistan, was tested for explosibility in 1.2 L Hartmann apparatus under various particle sizes and dust concentrations. First, a random forest algorithm was used to model the relationship between inputs (coal dust particle size, coal concentration and gross calorific value (GCV)), outputs (maximum pressure (Pmax) and the deflagration index (Kst)). The model reported an R2 value of 0.75 and 0.89 for Pmax and Kst. To further understand the impact of each feature causing explosibility, the random forest AI model was further analysed for sensitivity analysis by SHAP (Shapley Additive exPlanations). The study revealed that the most critical parameter affecting the explosibility of coal dust were particle size > GCV > concentration for Pmax and GCV > Particle size > Concentration for Kst. Mutual interaction SHAP plots of two variables at a time revealed that with <200 gm/L concentration, −73 µm size and a high GCV coal was the most explosive at a high concentration (>400 gm/L), explosibility is relatively lower irrespective of GCV and particle sizes.

Physico-chemical characteristics of pulverized coals and their interrelations-a spontaneous combustion and explosion perspective

Characteristics of pulverized coals have significant influence on the spontaneous combustion and explosion processes. This paper presents an experimental and theoretical framework on physico-chemical characteristics of coal and their interrelations from spontaneous combustion and explosion perspectives. The chemical properties, morphology, bulk density, particle size, and specific surface area of pulverized coals from nine different coal subsidiaries of India are vividly investigated in five distinct sizes. Moreover, the effects of particle size on bulk density, specific surface area, and N₂ adsorption capacity of pulverized coals are critically analyzed. With decrease in particle size, the bulk density of pulverized coals decreased, and the specific surface area and N₂ adsorption capacity increased. The relationships of bulk density and specific surface area of pulverized coals with particle size are established. Moreover, the specific surface areas determined by both the particle sizing and BET methods are compared, and correlation factors between them are determined. This study generated insightful coal characteristic data, which can be useful for furthering research on spontaneous combustion and explosion involving pulverized coals.

Characteristics of Dust in Coal Mines in Central North China and Its Research Significance

The identification of the dust characteristics in coal mine working faces is essential for preventing coal dust explosion and occupational diseases. In this paper, dust samples from the coal mines in southern Shanxi province and Henan province, central North China, were selected as the research objects. The results show that the dust contains primarily organic matter, as well as considerable amounts of minerals. The chemical composition of dust at the working faces is the most complex. According to the proportion of PM10, the dust composition can be divided into three types: symmetrical, fine-dominated, and coarse-dominated. The wettability of dust increases with the increase of the oxygen-carbon ratio on its surface, increase of ash content, decrease of fixed carbon content, and decrease of particle size. In addition, the great variety of harmful elements in dust, some with a high content, can harm the human body. An explosion index is proposed to evaluate the likeliness tendency of coal dust explosion based on several key affecting factors. The surfactant (0.05% AN solution) adopted in this paper can significantly increase the wettability of coal dust and inhibit the generation of dust greatly, showing good ability in preventing coal dust explosion and occupational diseases.

Explosion Pressure and Minimum Explosible Concentration Properties of Metal Sulfide Ore Dust Clouds

The explosion pressure and minimum explosible concentration (MEC) properties of metal sulfide ore dust clouds are valuable for the prevention and control of metal sulfide ore dust explosions. In this study, a 20 L explosion sphere vessel was used to investigate the effect of sulfur content, particle size, and concentration on the explosion pressure and minimum explosible concentration of metal sulfide ore dust clouds. Four samples with different sulfur contents were selected (30%–40%, 20%–30%, 10%–20%, and 0%–10%). Before and after the explosion, samples were tested by X-ray diffraction. The results indicate that the metal sulfide ore dust is explosive dust with St1 grade explosion pressure. With an increase in concentration, the maximum explosion pressure increased at first and then decreased. With an increase in sulfide content, the explosion pressure of metal sulfide ore dust increased, while the minimum explosible concentration decreased. As particle size decreased, the MEC also decreased. The sulfur content, particle size, and concentration of metal sulfide ore dust were the main factors affecting the explosion hazard.