Study on mineral liberation and energy consumption in coal under different pulverization modes

Liberation is the premise of achieving efficient coal separation. In order to improve the efficiency of coal separation, two kinds of grinding equipment, namely ball mill based on impact pulverization and stirring mill based on shear pulverization, combined with optical microscope and density analysis method to evaluate mineral liberation, were used, and the mineral liberation and energy consumption law of Yuandatan coal under different pulverization methods were systematically explored. The results show that the minerals in the coal are mainly irregular quartz, framboidal pyrite and laminated clay minerals, and the particle size distribution range of the minerals is 10−100 μm. There are multi-component and multi mineral intercalation, which is complex and difficult to liberate. After optimizing the grinding parameters, when the grinding speed is 300 r/min, the grinding time is 8 min, and the sample filling rate is 33.9%, the maximum mineral liberation is 58.81%, and the grinding energy consumption is 715.53 kJ/kg; When the grinding speed is 400 r/min, the grinding time is 30 min, and the sample filling rate is 40.0%, the maximum mineral liberation degree is 52.85%, and the grinding energy consumption is 2406.87 kJ/kg. By analyzing the law of mineral liberation degree energy consumption, it is found that the average liberation efficiency of shear pulverization is 5.5 times higher than that of impact pulverization, and the liberation effect of shear pulverization has the characteristics of high efficiency and stability. By comparing the crack fracture characteristics of impact and shear pulverization, it is found that the cracks in the process of impact pulverization are mostly disorderly propagation, and the probability of random liberation is high; shear pulverization promotes the directional propagation of cracks along the mineral coal interface through the shear force field, which improves the liberation efficiency and significantly reduces energy consumption. In depth study on the differences of mineral liberation characteristics and energy consumption characteristics in coal can provide scientific guidance for actual production, and is also of great significance to promote the progress of efficient coal separation technology.