Caterpillar has developed the Cat® GH800B Longwall Plow System, designed for mining very low coal seams at high rates. Building on the attributes of the proven GH1600 Plow System, the Caterpillar longwall team in Lünen, Germany, worked with the German Ibbenbüren mine to design and construct a system for mining an anthracite seam averaging only 0.85 meters (33.5 inches) thick. The result is the GH800B Plow and associated longwall system, which is now successfully operating in the Ibbenbüren mine—where the seam does not exceed 1.0 meter (39 inches) in height.
The Cat GH800 plow, with an installed power of 2 x 400 kW, has been the plow of choice for seam heights from 0.9 to 2.0 meters (35 to 78 inches), regardless of seam inclination or coal hardness. But the lower the coal seam, the more difficult the extraction process. Flexibility, reliability, efficiency and serviceability of the whole system had to be refined for maximum productivity in such a minimal height, but several key modifications led to success.
The armored face conveyor (AFC) modifications for the GH800B plow system include PF4 plow line pans with a replaceable top trough and a new plow guide made of a one-piece casting to provide extra strength and durability while 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 (shields) 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 plow body of the GH800B system was adapted to cutting heights from a maximum 1.55 meters (61 inches) to as low as 0.75 meters (30 inches). An optimized design at both ends of the plow body helps load more coal onto the face conveyor and reduces the amount of cutting power consumed by this process. The Cat GH800B enables an effective horizon control system, which provides the ability to follow the seam line without cutting adjacent rock.
The Cat low seam roof supports were also specially designed for this application. Shortened canopies avoid collision with the plow even in their lowest position, and the shield canopies are 8 centimeters (3 inches) thinner to create a more ergonomic working environment for the face crew. A canopy water spray sequence, synchronized with the cutting plow, keeps dust levels down.
Cat automation of the complete plow longwall as well as remote control of all functions and adjustments enables high production with no personnel at the face. The system enhances safety and minimizes operating cost.
The new GH800B plow system went underground for operation at Ibbenbüren mine in the fourth quarter of last year. In addition to impressive daily production, the new system reduces operating and maintenance costs by about 50 percent compared to a nearby coal face. An advance rate of as much as 10 meters (33 feet) per day reveals the enormous production capability of the system.
The Cat GH800B plow system is going to be operated in five consecutive longwall panels of the Ibbenbüren mine.