碟盘刀具破碎煤岩的粒度关联特征研究

Particle correlated characteristics of coal rock crushed by disc cutters

  • 摘要: 机械截割刀具与煤岩作用所形成破碎煤岩的形态、粒度分布特征和产尘特征,是综合反映破岩效率和作业安全的重要指标。基于碟盘刀具破碎煤岩的振动截割试验,分析煤岩破碎后的本体与破碎体的宏—细观形态特征。建立块粒度的熵表征模型并验证其度量破碎程度的可行性,利用激光粒度仪检测碟盘刀具破碎煤岩过程中漂浮性粉尘的尘粒度分布,采用极差和贡献度探究块粒度和产尘率的敏感性,分析破碎特征与破岩参数的关联特性。结果表明:碟盘刀具楔面与齿刃的结构特征,使破碎后的煤岩本体呈现出月牙形断面和断续性截割痕迹。破碎体中,大块煤岩多呈现片状月牙形,其中粒径大于8 mm的破碎煤岩块占比高,切削厚度对大块煤岩占比影响最显著,贡献度达73.11 %,振动频率和碟盘倾角对于增加煤岩的破碎程度呈正相关,破碎煤岩的块粒度分布特征可用Rosin-Rammler分布函数进行描述。尘粒的细观形态呈现多棱边形和近球形双态,进给速度的增加会加剧碟盘刀具与煤岩的接触机会,其对产尘率的贡献度为61.88 %,振动频率的增加导致产尘率呈上升趋势,碟盘倾角增加时,碟盘与煤岩的接触面积减小,致使产生粉尘的机会变少。

     

    Abstract: The morphology, particle size distribution and dust production of crushed coal rock formed by the interaction between mechanical cutting tools and coal rock are crucial indicators that reflect rock breaking efficiency and operation safety. This study conducted a vibration cutting experiment with cutting thickness, vibration frequency, feed speed and disc inclination angle as major parameters to investigate the macro-micro morphological characteristics of the body and the crushed body after coal rock was crushed by disc cutters. We established an entropy characterization model of block size, verified its feasibility of measuring the degree of fragmentation and discussed the block size distribution of the crushed body. We used laser particle size analyzer to detect the dust particle size distribution of floating dust in the process of crushing coal rock by disc cutter to analyze the characteristics of dust production. The sensitivity of block particle size and dust production rate was investigated in terms of range and contribution to analyze the correlation between crushing characteristics and rock breaking parameters. Results show that the structural characteristics of the wedge surface and the tooth edge of the disc cutter gave the crushed coal rock body a crescent section and intermittent cutting marks. In the crushed body, the large coal rock was mainly in the shape of a flaky crescent, where crushed coal rock with a particle size longer than 8mm took up a high proportion. Cutting thickness exerted significant effect on the proportion of large coal rock, with a contribution rate of 73.11 %. Vibration frequency and the inclination angle of the disc were positively correlated with the degree of fragmentation of the coal rock. The particle size distribution of the crushed coal rock could be described by the Rosin-Rammler distribution function. The microscopic morphology of the dust particles was polygonal and nearly spherical.The increase of feed speed would aggravate the contact opportunity between the disc cutter and the coal rock, and its contribution to the dust production rate is 61.88 %. The increase of the vibration frequency led to an increase in the dust production rate. When the inclination angle of the disc increased, the contact area between the disc and the coal rock decreased, resulting in fewer opportunities for dust generation.

     

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