Abstract: Adpoting liquid nitrogen as refrigerating medium, a cryogenic grinding system was set up to cool the printed circuit board material to its embitterment temperature. The effects of freezing temperature and processing time and setting conditions on the particle size distribution were examined. Orthogonal experiments were carried out to determine the optimal working conditions. The results show that the fractal dimension of product is 1.94 with regular particle size, and the yield of 0.5~1.4 mm particles is 43.8% when the cooling temperature is -30℃. There is no evident change of fractal dimension for different processing times. When the processing time is longer, cutter gap lower and frequency bigger, the yield is higher. The best working condition will be achieved when the crushing time is 10 min and discharge size of crusher is not less than 3 mm.

Key words: printed circuit board, cryogenic grinding, size distribution, fractal dimension, yield

摘要： 利用自行搭建的系统进行了废旧印刷电路板的细碎实验，分析了不同冷却温度、破碎时间、破碎机转速、刀具间隙、排料尺寸对废旧电路板物料粒度分布与产率的影响，并采用正交实验优化了细碎机的工艺参数. 结果表明，冷却温度为-30℃时粒径0.5~1.4 mm的合格产品产率较高，为43.8%，产物粒度分形维数最小，为1.94，粒度分布规则；不同破碎时间的产物粒度分形维数变化不大. 正交实验结果表明，破碎时间越长越有利于提高产率，提高产率需减小刀具间隙、提高破碎转速，最佳破碎时间为10 min，刀具间隙不小于3 mm.

关键词: 印刷电路板, 低温破碎, 粒度, 分形维数, 产率