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Working In the Salt Mines - Terex Trucks

Irish Salt Mining and Exploration’s Carrickfergus mine

plays a vital part in keeping the UK’s road network open

during winter.

Situated to the north of Belfast, Northern Ireland,

Irish Salt Mining and Exploration’s (ISME) Carrickfergus

mine was developed specifically to mine de-icing rock

salt for winter road maintenance.

Founded in 1965, ISME is positioned in a prime lo-

cation, thanks to its proximity to the coast, as well as

the construction of a ship loading terminal, which ena-

bles the company to develop a successful export


The company’s 55-strong workforce currently pro-

duces between 300,000 to 500,000 tonnes of road salt

per year, and provides local authorities across the UK

with rock salt to help keep the road network open during

the icy winter months.

Scottish local authorities are its biggest customer,

followed by Ireland and then the rest of the UK.

Rock solid progress

Mining at Carrickfergus uses the ‘room and pillar’ dry

mining method. There are five seams of salt, but ISME

only mines one extensively, due to the thickness of the

seams. (This is because 3.5m (12ft) of salt must be left

above the excavated rooms as a support.)

At its deepest point, the mine reaches 305 m (1,000 ft)

below ground.

“The deeper you get, the larger the pillars, but

on average the room sizes are 15.3 m (50 ft)

wide and 9 m (30 ft) high. In the older part of

the mine, they are just 6.7 m (22 ft) high, while

the pillars are 39.6 m (130 ft) square in the

newest part of the mine, and 27.4 m (90 ft)

square in the older parts.”

explains Moore.

The geology of the area is fairly simple too. There

are no gases or moisture to contend with, which makes

mining a simpler process too.

During mining, the salt bed is undercut then drilled

and blasted. Blasting happens at the end of each 10-hour

shift, usually around 17.30, and sees three faces advance

3 m (10 ft) each time. The next morning’s first job is roof

scaling, using a rotary cutting head designed specifically

for the purpose.

The broken salt is then loaded into one of ISME’s

seven Terex Trucks haulers, including two new TA400s,

and hauled to the crushing plant.

Crushing and screening are completed underground

before the finished product is transported, via a 2 km-

long network of conveyors, to the surface.

The salt, ready for use, is then treated with an anti-

caking additive and stored undercover for dispatch by

sea from the company’s own quay, or by road.

Keeping to the mine’s speed limit is a key factor in

reducing wear and tear, as well as minimizing fuel con-

sumption. But the working conditions are still extreme,

with the trucks having to cope with corrosive salt and

dust, not to mention the temperatures inside the mine.

Terex Trucks

Contractors World UK Ireland Vol 6 No 2