In an effort to lower backfill cost, uncemented, cycloned mill tailings are sometimes placed down the centers of the drifts as the backfill lifts are placed. The sides of the drif ts next to the pillars are backfilled with cemented backfill for a distance of 3 m from the pillars. This leaves 4 m of uncemented tailings in the middle. Both materials are placed by loaders. This process continues until the fill reaches 3.5 m from the back, after which is modified
regular topping-off takes place. The backfill sequence is modified when trapped pillars (pillars that have backfill on all four sides) are involved. This modification involves placing uncemented cycloned tailings on one side of the trapped pillars starting from
the floor and progressing to the back as subsequent lifts are
placed. The uncemented cycloned tailings are later removed through
into the sand. This creates a void into which the trapped pillars can be blasted