Clearance and reconstruction of the »Halle« shaft and the drifting of a connecting-passage between mining claims Angersdorf and Teuschenthal

The former potash and stone salt zone is located west of the city of Halle and consists of the Teuschenthal, Angersdorf, and Salzmünde mining claims. The working sections of the mines extend in a wide arc of about 10 km in lenght and 2 km in width from Angersdorf to the B80 main street at Teutschenthal railway station junction.  

The mining in this working section began in 1905 and was stopped in 1982 for economic reasons.  Since 1992 the mine Teuschenthal Sicherungs GmbH & Co. KG (GTS) has been operating the mine as a backfill mine and connecting the necessary filling of the cavities with intrusion of industrial waste materials. To ensure the further safekeeping operation, a connecting passage between both mines Angersdorf and Teutschenthal needed to be driven as well as the shaft »Halle« had to be renovated and reconstructed. The Teutschenthal mine return air was initially led to the shaft »Halle« via ventilation road. Due to the rock burst of 1996 and the resulting downfall in the eastern part of the mine Teutschenthal the weather situation was worsened drastic and made the new drivage of a connecting passage to the mine Angersdorf necessary.

Due to weather situation, the driving could be realized only from the Angersdorf mine field via the shaft Halle. Since this shaft had previously served as a ventilation shaft, it first had to be renovated and converted. For that, the disused shaft was cleaned, damp spots in the brick masonry and tubbing were grouted, and the existing shotcrete support was partially replaced. The bottom landing on the 1^st level was enlarged, secured with nets and equipped with a crane track. The underground workshop and transformer room for power supply were installed directly at the filling site. All the large devices needed for roadway drivage were brought underground in disassembled state via still empty shaft and reassembled at the filling site by using the crane track. After completion of the large equipment transport, the installation of a new men hoisting installation into the Halle shaft began. The bottom landings on the grass root and 1^st level were complete new built and designed for a two strand vehicle operation (one run for the regular travel with the middle rope installation and a second run for the emergency travel with the bucket). Due to these works, it was also necessary to rebuild the rope sheave displacement in the hoist frame several times. The system was completed by the installation of the necessary safety and signal equipment. In the machine house, the existing hoisting machine was moved to another location and is now used for the operation of the emergency hoisting system. The new men hoisting installation was equipped with a SIEMAG hoisting machine, also new, which was positioned in the renovated machine house.

At the same time, the driving of the new connection passage could start.  The roadway run to the direction east and west from the rock salt level of the Angersdorf mine field to potash level of the Teutschenthal mine field, and act essentially as escape  and ventilation roadway. It was designed as a single roadway in rectangular profile with a standard cross-cut of 18.2m at a width of 5.2 m and a height of 3.5 m, and enables the discharge of a weather volume of approx. 4.500 – 5.000 m³/min. The drifting was carried out in horizontal part of the linen rock salt, about 50m above the potash repository. A 125 m long spiral road was driven from the level of the rock salt production floor (bottom landing of Halle shaft -542.8 mNN) to the western ventilation road on level -525.4 mNN. Subsequently, the western ventilation road, which connects the former mining chambers I – XIX, was widened to a length of 690m to the above mentioned rectangular profile by tearing of originally 4 m wide and 2 m high. The route and gradients of the existing roadway were not changed, so that this section of roadway still has the multiple changes in gradient with which the western ventilation road was originally constructed in 1931. At the end of the old ventilation line, driving of the new connecting passage continued in a western direction with a safety distance of approx. 5 m to the anhydrite in the horizontal section. At station 0+2,779 at the level of -561.4 mNN, the drifting left the rock salt horizon. With a sharp change of direction to the south and a steep dip of 17%, the last 240m section penetrated the main anhydrite and the underlying grey salt clay, and finally at Station 0+3,019 at a level of -602.9 mNN, it broke through into the floor 3a of the potash deposit of the Teutschenthal mine. The drifting was carried out with low vibration using an AM-75 roadheader. The excavated material was backfilled with dump trucks and loaders into the former mining chambers II to XIX, which are accessible via the western ventilation roadway.