关键词: 散体颗粒, 损失率, 贫化率, 相对粒径

Abstract: For the choice of backfilling waste rock in the pit III of Sijiaying iron mine during transferring from surface mining to underground，the PFC2D is used for simulating the ore drawing process，and the results of simulation are regressed and analyzed to obtain the equation between relative particle size and the rate of ore loss and dilution，which provides a theoretical basis to the choice of backfilling waste rock in engineering.This method can minimize the loss and dilution rate during ore-drawing to ensure the economic benefits for mimes.In addition，Matlab is used to establish a single-factor impact to the equation，and get the relationship between various factors and the rate of ore loss and dilution.

Key words: Granular particles, The rate of loss, The rate of dilution, Relative particle size