Caterpillar has developed the GH800B coal plough system for the rapid extraction of very thin seams. Building on the operating features of the tried and tested GH1600 plough system the Caterpillar coal face team in Lünen (Germany) collaborated with personnel from Ibbenbüren coal mine (RAG Anthrazit Ibbenbüren GmbH) to design and build an installation capable of working an anthracite seam with an average thickness of just 0.85 m. The result is the GH800B coal plough and face installation, which is currently operating successfully at Ibbenbüren mine.
The Cat GH800 plough, which has a rated output of 2 x 400 kW, was the preferred machine for seam heights of 0.9 to 2.0 m, irrespective of the seam gradient and hardness. However, the lower the seam, the more difficult the winning operation becomes. Some general improvements in the flexibility, reliability, efficiency and serviceability of the overall system were needed if high productivity levels were to be maintained in very thin seams – and a number of important design changes were made that ultimately brought success.
Modifications to the face conveyor for the GH800B plough system include the use of PF4 conveyor pans with a replaceable top trough and a new plough guide made from a one-piece casting that provides extra strength and durability while also being much lower in height than the previous welded version. External dogbone connectors between the line pans and a very strong and flexible relay bar between the AFC and the roof supports further adapt the conveyor for very low seam operation. To increase coal throughput, the engineering team widened the conveyor cross-section with extended side plates.
The GH800B system has been adapted for cutting heights ranging from a maximum of 1.55 m to as low as 0.75 m. Optimised design at both ends of the plough body helps load more coal on to the face conveyor and reduces the amount of cutting power consumed. The Cat GH800B also enables an effective horizon control system that provides greater ability to follow the seam line without cutting adjacent rock.
The Cat low-seam roof supports were also specially designed for this particular application. These have shortened canopies to avoid collision with the plough, even in the lowest setting. The shield canopies are also 8 cm thinner to create a more ergonomic environment for the face crew. An additional canopy water-spray sequence has been designed to synchronise with the cutting plough and so minimise dust levels.
Cat automation of the entire longwall plough system, along with remote control of all functions and settings, results in a high production rate without the need for on-face personnel. This both increases safety and reduces operating costs.
The GH800B plough installation went into service at Ibbenbüren mine in the fourth quarter of last year. The new system shows a 50% reduction in operating and maintenance costs over a comparable coal face. An advance rate of as much as 10 m a day reveals its enormous production capability. The Cat GH800B longwall plough system is to be used in five successive coal panels at Ibbenbüren mine.
Zeppelin Baumaschinen GmbH