longwall mining




Beam stage loader and crusher



Beam Stage Loader and Crusher

When the coal has been hauled to the maingate, it then has to be transferred through a 90o turn, and loaded onto the maingate conveyor. This function is carried out by the "Beam Stage Loader or BSL", which is another scraper conveyor, in this case with steel plates on both sides and runs from the maingate drive to the maingate conveyor (belt). The BSL has a change of elevation (a vertical curve) along its length in order to discharge coal onto the maingate conveyor and. in almost all cases, a crusher or breaker is mounted on the BSL to improve loading onto and to prevent damage to the outbye conveyors. The BSL ends above the boot and is normally attached to it with an attachment able to rotate horizontally (and with a limited amount of vertical flexibility).

In most cases, the BSL runs past the maingate drive to the goaf side and the AFC is slightly elevated where the two scrapers cross. There being no base plate to the AFC at this point the coal drops from the AFC onto the BSL. This design is known as a 'side discharge'and a curved guide plate is often mounted across the BSL at the loading point to assist in guiding the coal around the right angle turn.

An alternative arrangement is where the AFC stops at the face side edge of the BSL scraper so that the two scrapers do not overlap. This is known as "end discharge" and could be preferred where slabby stone may have to be handled.

The crusher or breaker is usually located along the low section of the BSL and is usually a rotary breaker with the drum acting against the floor of the BSL scraper conveyor.

The BSL section with the vertical curve or "Goose Neck" normally comes as one piece, but the horizontal section between the maingate drive and the crusher is made up of a number of "pan " sections which have some flexibility, similar to AFC pans.

The BSL is usually attached to the maingate drive and is moved forward by the maingate supports at the same time as the drive is advanced.