Building on the attributes of the GH1600 plough system, the Caterpillar longwall team in Lunen, Germany, worked with the Ibbenburen mine to design and construct a system for mining an anthracite seam averaging only 0.85m thick.

The new GH800B plough system went underground for operation at Ibbenburen mine in the fourth quarter of last year.

The new system reduced operating and maintenance costs by about 50% compared to a nearby coal face. An advance rate of as much as 10m per day revealed the production capability of the system.

It is going to be operated in five consecutive longwall panels of the mine.

The Cat GH800 plough, with an installed power of 2 x 400 kW, is suitable for seam heights from 0.9 to 2.0m, regardless of seam inclination or coal hardness.

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 armoured face conveyor (AFC) modifications for the GH800B plough system include PF4 plough line pans with a replaceable top trough and a new plough 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 plough body of the GH800B system was adapted to cutting heights from a maximum 1.55m to as low as 0.75m.

An optimised design at both ends of the plough 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 plough even in their lowest position, and the shield canopies are 8cm thinner to create a more ergonomic working environment for the face crew.

A canopy water spray sequence, synchronised with the cutting plough, keeps dust levels down.

Cat automation of the complete plough 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 minimises operating cost.