Backfilling of the old mining chambers
Rock mechanical stability analyses showed that by backfilling the underground chambers with compatible material the stability of the Asse Mine can be increased significantly.
Therefore, from August 1995 to April 2004, the old mining chambers in the southern flank of the Asse Mine were backfilled with residual salt from the former potash mine Ronnenberg near Hannover.
- Salt heap of the former potash mine Ronnenberg near Hannover
- Five days a week, 18 waggons – loaded with about 1200 tons of backfill material – were transported from Ronnenberg via Wolfenbüttel to the Asse mine by rail.
- The waggons were unloaded into a surface silo. From the silo, the backfill material was unloaded onto a conveyor belt which forwarded it to a blower unit. From there, it was further transported in a pipe system with compressed air from the surface directly down to the chambers to be backfilled. By means of a swivel device, movable both in vertical and horizontal direction, it was possible to blow the material to the requested location in the mining chambers to be backfilled.
- Backfilling a chamber at the 637 level
- By means of a remote-controlled bulldozer, the backfill material can be distributed evenly
- With a push blade, the chambers are densely backfilled up to the hanging wall
Except for a few residual ones, the mining chambers between the 725 and 490 m level have completely been backfilled. Altogether, about 2.15 million tons of residual salts were filled into the mining chambers of the southern flank of the Asse Mine.
- Backfill history (Backfill in tons, Annual volumes)
Further information: 5th information meeting on the way to a safe closure of the Asse mine on 13.05.2004: The mining chambers in the southern flank are backfilled, backfilling the deep workings was started. (in German)