The paper has a discussion on the appropriateness,feasibility and effectiveness of putting the wastedump of the underground mine in the surface dip offset zone,makes an analysis on soft and hard factors of hidden dangers during waste rock dumping and introduces corresponding safety measures.

These characteristics were influenced by structure factors(shape of bottom of tank, impeller type and gas sparger),operational factors (rotational speed, gas rate and particle fraction) and property factors(particle diameter and density), et al.