Abstract: There exists a great quantity of coal resources under "Three Unders" in some coal mine. In order to maximize recovery of coal pillar and resolve the problem in coal gangue discharge, the experimental research on rapid filling of paste-like coal gangue is carried out. Based on the analysis of experimental results on the strength of backfilling and the setting time, the paper determined the optimum ratio, which met the intensity demand and owned a short setting time. The rapid filling with paste-like coal gangue is effective and environment-friendly. This method provides a valuable and technical support for recovering "Three Under" overstocked coal mine, with a promising prospect.

Key words: Coal gangue, Ratio, Strength of backfilling, Setting time