Optimization of Stope Structural Parameters in Phosphorite Mine and its Stability Analysis

Abstract

A mine plans to exploit the low dip thin phosphate deposit by room-and-pillar mining. But a township highway is just above the orebody, and its distance is only 80m, in order to better control the ground pressure in stopes and ensure the operation security, the size of room and pillar must be reasonably designed to maintain the stability of stopes and surrounding rock. The 3D-σ numerical simulation method was applied to analyze the surrounding rock stability in different stope structure parameters. The results show that when holding the size of pointed prop unchanged, the surrounding rock stability would decline with the increase of room width and pillar spacing, for security, the mining plan, the pointed prop is 3×3 m, the stope width and pillar spacing is not more than 9 m, were considered to be one of the optimal. In addition, it is important to emphasize that if the mining depth exceeds 300m, some methods, such as decreasing the spacing of stope and pointed props or increasing the pillar size, need to be taken to avoid the stope instability caused by greater ground pressure.