School of Energy and Mining Engineering, China University of Mining and Technology, Beijing, China.
China Coal Energy Research Institute, Xi' an, China.
PLoS One. 2023 Feb 17;18(2):e0281513. doi: 10.1371/journal.pone.0281513. eCollection 2023.
This study investigates the fractal characteristics of the particle size and shape distribution of gangue powder in the "jaw crushing-ball milling" process using mudstone gangue. For this, fractal theory, laser particle size analyzer, scanning electron microscope and other mesoscopic research methods were introduced. This study has several main factors, including the discharge port width in the jaw crushing stage, the grinding particle size, ball-to-powder ratio in the ball milling stage, and the fractal dimension changes of the gangue in different crushing stages. The results indicate that in the process of "jaw crushing-ball milling", gangue's particle size and shape fractal dimension values changed periodically. During the jaw crushing stage, the particle size fractal dimension increases with the width of the discharge opening, ranging from 1.85 to 1.92. The value of the shape fractal dimension varies from 2.65 to 2.84. Ball milling causes the fractal dimension value of gangue particle size to increase with time before agglomeration and decrease after agglomeration. By comparing different in-grinding particle sizes and ball-to-powder ratio, it is found that the fractal dimension value of gangue particle size decreases with the increase of in-grinding particle size and increases with the increase of ball-to-powder ratio. The final gangue's particle size fractal dimension value is concentrated between 2.5 and 2.8. The fractal dimension of particle shape increases with the increase of the grinding particle size, and decreases with the increase of ball-to-powder ratio. A ball-to-powder ratio greater than 6 gradually reduces its influence on fractal dimensions, and the final shape dimension lies between 1.06 and 1.16. In addition, the increase/decrease range of particle size and shape fractal dimension decreases with the increase of ball milling time, which is also consistent with the grinding kinetics theory. As a result of the changes in particle size and shape fractal dimensions, parameters such as jaw crusher discharge port width, grinding particle size, and ball-to-powder ratio are calculated to provide a theoretical basis for the entire crushing process in the "jaw crusher-ball milling" crushing process.
本研究采用泥岩矸石，研究了“颚破-球磨”过程中矸石粉末粒径和形状分布的分形特征。为此，引入了分形理论、激光粒度分析仪、扫描电子显微镜等介观研究方法。本研究的主要因素包括颚破阶段的排料口宽度、球磨阶段的研磨粒径、球料比以及不同破碎阶段矸石的分形维数变化。结果表明，在“颚破-球磨”过程中，矸石的粒径和形状分形维数值呈周期性变化。在颚破阶段，随着排料口宽度的增加，粒径分形维数增加，范围在 1.85 到 1.92 之间。形状分形维数的变化范围在 2.65 到 2.84 之间。球磨使矸石颗粒粒径的分形维数值在团聚前随时间增加而增加，在团聚后减少。通过比较不同的研磨粒径和球料比，发现矸石颗粒粒径的分形维数值随研磨粒径的增加而减小，随球料比的增加而增大。最终矸石的粒径分形维数值集中在 2.5 到 2.8 之间。颗粒形状的分形维数随研磨粒径的增加而增加，随球料比的增加而减小。球料比大于 6 时，其对分形维数的影响逐渐减小，最终形状维数在 1.06 到 1.16 之间。此外，粒径和形状分形维数的增减范围随球磨时间的增加而减小，这也符合磨矿动力学理论。由于粒径和形状分形维数的变化，计算出颚式破碎机排料口宽度、研磨粒径和球料比等参数，为“颚式破碎机-球磨机”破碎过程中的整个破碎过程提供了理论依据。
