废弃电路板破碎产物粒度分形分布的研究

废弃电路板破碎产物的外观形貌具有统计意义的自相似性,表现出分形的特征,建立了废弃电路板破碎产物粒度分布的分形模型.应用Origin 7.0软件对18种不同实验条件下得到的筛下累积产率曲线进行函数拟合,得到的拟合结果和实际结果相关性较好,残差E值较小,说明分形维数D是反映废弃电路板破碎程度恰当的统计特征量,可作为评价废弃电路板破碎程度的重要参量.采用Design Expert 6.0.8软件建立了分形维数D和破碎实验操作条件之间的二次方模型,标准偏差为0.022 706,且二次方模型得到的预测值和实际值非常接近,残差、平衡值、学生化残差、库克距离和奇异点距离均能达到预测精度的要求,为废弃电路板的湿法高效冲击破碎提供了基础.

Research on the Fractal Model of Size Distribution of Crushed Waste Printed Circuit Boards

The surface topography of crushed particles of waste printed circuit boards (WPCB) manifests self-similarity, which shows the fractal characteristics. A fractal model of size distri-bution of particles of WPCB was proposed. The eighteen curves of cumulative weight percent-age undersize of WPCB under different experimental conditions were fitted by the Origin 7.0 software. The correlation coefficient between the fits values and the factual values was closed to 1, and E of residual value is small, which shows that the fractal dimension D is an appropri-ate parameter indicating the fragmentation degree of WPCB. The Design Expert 6.0.8 soft-ware was used to establish a quadratic model between the fractal dimension D and the operating variables. The standard deviation is 0.022706. The predicted value based on the quadratic model is close to the actual value. All assessment indicators of residual, leverage, student re-sidual, cook's distance and outlier reached the required standard, which provide a credible foundation for effective wet crushing of WPCB.