This is the first stage of the mining process. A cut of 3 metres in depth is made along the bottom of the development heading to allow a free face for blasting. This cut also creates a smooth floor and sets the gradient for the mine roadway.
The Wabco undercutter, which is electrically powered, rotates a 3 metre blade with 57 tungsten carbide tipped cutting teeth.
2. DRILL & BLAST
Next the working face is drilled with up to 96 horizontal holes.
ISME use Oldenburg single boom drills. These are electrically powered drills mounted on diesel vehicles, and have a 3 metre steel drill rod with a tungsten carbide bit.
The drill holes in the working face are then filled with ANFO (Ammonium Nitrate Fuel Oil).
The Normet Anfo Loader has a hydraulic boom with a man-lift basket to reach the drilled holes. Trained shot-firers load primers and ANFO into the holes, before preparing the face to be fired.
After a blast, the resulting roof is scaled to remove any loose material.
The Terex Fuchs 350 scaler is fitted with a Webster Schaeff twin rotary head with over 100 picks. The hydraulic boom, with a reach of up to 16 metres, scales the roof clear of any loose material. The operator cab can be hydraulically raised up to a height of 5.5 metres to give better visibility.
5. HAUL FROM FACES
Once the room is scaled, the fragmented salt is loaded by Cat 980M front end shovels onto Terex TA400 articulated dump trucks. These dump trucks can each carry approximately 30 tonnes of blasted salt to the underground crushing plant or stockpiles.
The salt is loaded onto the underground Stamler primary crusher. This is a single drum feeder breaker with carbide-tipped picks, which breaks the rock salt down to <250mm. It is then transported by 1km of conveyor to the main processing plant, which is made up of a triple drum crusher, 3 x twin roll crushers and 4 x finishing screens.
This crushes the salt down to <6.3mm Fine Grade, before travelling 4km by conveyor to the surface storage shed. As it comes out of the mine by conveyor, Yellow Prussiate of Soda (YPS) an anti-caking agent, is added to prevent the salt from re-crystalizing.
The surface storage shed can hold up to 60,000 tonnes of the final product, ready for dispatch. When the surface shed is full there is the capacity to store blasted material underground.
For customers throughout Ireland, salt is contracted to local hauliers who have a good knowledge of the depots and region, offering a reliable and efficient delivery service. Orders can be started immediately and are loaded directly from the surface storage shed to transportation.
Irish Salt Mining’s own ship loading facility provides a deep water berth with a minimum draft of 9 metres of sea water. It is capable of handling vessels of up to 175 metres in length, with an average loading rate of around 1000 tonnes per hour.