Potential use of high-density backfill in Illinois Basin room-and-pillar coal mines

Transactions of the Society for Mining, Metallurgy, and Exploration , 2014, Vol. 336, No. 1, pp. 396-401

Spearing, A.J.S. (Sam); Benton, D.; Kostecki, T.; Hirschi, J.C.

The use of paste backfill in room-and-pillar coal mines in the United States needs to be fully investigated. This paper discusses a series of physical tests that were conducted to examine the support benefits of theoretical paste backfill regimens in Illinois Basin room-and-pillar coal mines, which necessarily included consideration of weak floor conditions. The series of tests included those simulating strong floor conditions, weak floor conditions, under-confined scenarios, and testing of actual coal-based paste backfill samples. The testing indicated that a paste backfill regimen utilizing a minimum backfill strength of 22 psi at a minimum fill height of 50% of pillar height could significantly increase the longterm stability of coal pillars in the Illinois Basin. Considering typical coal wash plant recoveries, 50% fill would be feasible.