Deutsche Steinkohle geomechanics and roadway support expert Klaus Opolony and DMT senior mining engineer Holger Witthaus presented a paper on the re-use of roadways, the efficiency and costs of this method and the tools needed to perform this type of roadway system at the International Conference on Ground Control in Mining recently.

The world’s most popular method of longwall mining requires multiple entry systems for panels. In contrast, roadways in German coal mining used advanced mining from the rock mechanic point of view and the roadways were even re-used by a second panel.

German coal mining in deep mines, up to 1450 metres to 4800 metres deep, use roadways that are driven in single entry systems at both sides of the longwall and are kept open after the face passage. Where possible, the roadway between the panels is re-used.

This system flies in the face of roadways in most other countries where the longwall roadways are not kept open after the passage of the face line and are used in a retreat mining method. The roadways are usually developed in straight lines connected by crosscuts where an optimal roadway shape is maintained for the whole length of the panels.

The support is designed for stabilising the loose strata areas and high rates of development, which average 150 metres per day.

Opolony and Witthaus said the best way of handling advanced mining multiple processes is through detailed planning procedures and well-educated staff. Training, technical improvement and planning can be achieved through the use of 3D-visualisation software.

Virtual reality applications includes a virtual copy of realistic processes in the virtual world (VR World), a simulation of the surrounding environment with original control elements (VR-Simulator) and a combination of different cooperating work stations in a training centre (VR Training Room).

Processing, planning and optimisation software (PPO) is used to select the best equipment for the roadway drivage. It can then be used to provide the specifications for carrying out roadway drivage operation.

A comparison of multiple and single entry roadway systems for highly stressed roadways can be executed using the PPO software.

“The comparison of multiple entry systems VS re-use of single entry roadways shows significant benefits in roadway development costs for multiple-entry systems,” said Opolony and Witthaus.

“The benefits are depending on the developing rate and therefore they are influenced by the roadway size and the support density. Even under high stress conditions the costs are less than half of the costs for re-used roadways.

“The length of roadways in the whole influences the benefits in the specific costs related to the extraction. Multiple entry system requires more than double length to be developed.

“Peripheral needs mostly are responsible for re-use of roadways. Especially the influence of remnant pillars on the stress situation for mining deep seams with multiple seam mining is important.”