Backfilling technology and strata behaviors in fully mechanized coal mining working face

Abstract Based on the principle of fully mechanized backfilling and coal mining technology and combined with the Xingtai Coal Mine conditions, we mainly optimized the coal mining equipment and adjusted the coal mining method in the Xingtai Coal Mine 7606 working face for implementation this technology. Firstly, we define the practical backfilling process as the “(from backfilling scraper conveyor’s) head to tail backfilling, step by step swinging up of the tamping arm, gradual compacting, moving formed backfilling scraper conveyor when the second tamping arm cannot pass and connecting the immediate roof by back material push front material movement”. Meanwhile, the stress changes of backfill body in coal mined out area was monitored by stress sensors, and the roof caving law was analyzed by monitoring the dynamic subsidence of −210 west roadway of this face. The site tests results show that using this new backfilling and coal mining integrated technology, the production capacity in the 7606 working face can reach to 283,000 ton a year, and 282,000 ton of solid materials (waste and fly ash) is backfilled, which meets the needs of high production and efficiency. The goaf was compactly backfilled with solid material and the strata behavior was quite desirable, with an actual maximum vertical stress of the backfill body of 5.5 MPa. Backfill body control the movement of overburden within a certain range, and there is no collapses of major areas in the overlying strata upon backfilled gob. The maximum subsidence and speed were 231 mm and 15.75 mm/d respectively, which proved the practical significance of this integrated technology.