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Located two miles east of the village of Coxhoe, County Durham, Raisby Quarry has been producing aggregate for over a hundred years. The quarry is now owned by the Breedon Group of companies which operates almost seventy quarries throughout the British Isles. Recently the Breedon Group has successfully gained planning permission for a further 24 years of mineral extraction at the site which runs through to 2042. Production from the quarry is about 1.2 million tonnes of aggregate per annum which is primarily used in the manufacture of cement. Currently the quarry staff number 22 direct employees, working a single shift per day, five days a week. Permian Magnesian Limestone from the quarry is initially processed through a 56inch Jaw crusher with subsequent reduction through secondary and tertiary cone crushers. Crushed rock is conveyed to the top of the screen house where it is fed directly onto a 2m wide Mogensen Sizer.

Raisby Quarry
























The current Mogensen Sizer was originally built and installed in 1984 and will have handled in the order of 30 million tonne of aggregate over its working life to date. The Sizer is equipped with six screen decks and daily through put is about 5000 tonne per day with the Sizer being used to remove dust from the crushed rock prior to the final screening processes.

Raisby Quarry
Raisby Quarry


















The sizer with its angled decks and increased mesh apertures enable high volumes of material to be screened efficiently in a relatively small floor space. The amplitude of the sizer is 10mm and the linear vibratory action is provided by a pair of Invicta vibrators.

Raisby Quarry


















The original specification called for a pair of B955/6 Invicta vibrators to provide linear vibration to the Sizer. An original B955/6 vibrator can be seen bolted to the mounting beam below the Sizer and this will have been running for approximately 80000 operating hours. The B900 series of vibrators has now been superseded by the BLz series of vibrators which is fully interchangeable with the older designs. The BLz series is approved for use in Zone 21 & 22 areas and is designed with IP66 protection to prevent dust ingress to the internal components. Invicta vibrators are continuously rated for use in hot and dusty environments and have been used successfully in all parts of the world.