Since the mid-1970s two type-1054 Mogensen Sizers have been working in the slate granule plant at McAlpine's Bethesda Quarry in North Wales. Further vibratory equipment has recently been bought by McAlpine as part of a scheme to improve the layout and efficiency of the plant.
Mogensen have supplied a 1m wide feeder, a trough conveyor, a 1m wide type-C2044 screen and a 2m spreader feeder. The two original type-1054 Sizers, one of which was previously operated without a feeder, have been re-employed in parallel in the new plant along with the original Mansfield crusher.
The 1m feeder has been coupled with the Sizer that lacked a feeder to improve its screening efficiency. Three grades of material are produced: oversize for recycling to the Mansfield crusher, saleable granules, and fines. The trough conveyor takes the granules from the Sizers to the spreader feeder positioned ahead of the new C2044 screen, which, in turn, separates the granules into the various grades required.
The C2044 is fitted with four screen decks, each of which is made up of two 1m mesh panels placed either side of a central dividing wall. The mesh panels and screen tensioners are the same as those used in the 1054 Sizers, reducing the number of spares held on site. The drive for the C2044's circular motion vibratory action is provided by two of Invicta's latest L-series BL45-45/4 rotary electric vibrators which are linked together via shaft extensions and a flexible coupling.
All the Mogensen machines, both new and old, and the transfer points between them are fully dustproofed. The rebuilt plant is reported to have satisfactorily achieved the aims of improved screening efficiency, improved product recovery and better accessibility for maintenance purposes.