不同粉碎方式下煤中矿物解离与能耗规律研究

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

  • 摘要: 解离是实现煤炭高效分选的前提,为提高煤炭分选效率,使用以冲击式粉碎为主的球磨机和剪切式粉碎为主的搅拌磨机2种磨矿设备,结合光学显微镜法和密度分析法评价矿物解离,系统探究了袁大滩煤在不同粉碎方式下的矿物解离与能耗规律。结果表明:煤中矿物以不规则状石英、草莓状黄铁矿及层片状黏土矿物为主,矿物粒度嵌布范围为10~100 μm,存在多组分和多矿物互相嵌布的情况,矿物嵌布复杂且解离难度较高。在优化磨矿参数后,剪切式粉碎在磨矿转速300 r/min、磨矿时间8 min、样品充填率为33.9%时,矿物解离度最高为58.81%,磨矿能耗为715.53 kJ/kg;冲击式粉碎在磨矿转速400 r/min、磨矿时间30 min、样品充填率为40.0%时,矿物解离度最高为52.85%,磨矿能耗为2 406.87 kJ/kg。分析矿物解离度−能耗规律发现,剪切式粉碎的平均解离效率是冲击式粉碎的5.5倍,剪切式粉碎的解离效果兼具高效性与稳定性的特点。对比冲击式和剪切式粉碎的裂纹断裂特征发现,冲击式粉碎过程中裂纹多为无序扩展,随机解离概率较高;剪切式粉碎通过剪切力场促进裂纹沿矿物−煤界面定向扩展,在提升解离效率的同时显著降低能耗。通过深入研究不同粉碎方式对煤中矿物解离特性与能耗特征的差异性,可为实际生产提供科学指导依据,也对推动煤炭高效分选技术的进步具有重要意义。

     

    Abstract: 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.

     

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