Boulby Mine is a 200-hectare (490-acre) site located just south-east of the village of Boulby, on the north-east coast of the North York Moors in Redcar and Cleveland, England. It is run by Cleveland Potash Limited, which is now a subsidiary of Israel Chemicals Ltd.
It produces half of the UK's output of potash, an agricultural fertiliser. The mined ore consists of 35–45% sylvite ("potash", specifically potassium chloride) and 45–55% halite (rock salt, or sodium chloride). The rock salt is extracted as a by-product and used across the region as a de-icing agent on roads in winter conditions.
The mine has 1,001 employees and can produce up to one million tonnes of potash each year. At 1,400 metres (4,600 ft) deep, it is the second deepest mine of any kind in Europe, and has a network of underground roads extending under the North Sea, totalling 1,000 kilometres (620 mi) in length.
Cleveland Potash Limited had a reported turnover of £194 million in 2013, up from £162 million the year before. However despite the increased turnover, the company suffered a total pre-tax loss of £194 million. This was the result of a huge £200 million impairment charge arising from a significant fall in potash prices.
In 1939, potash was discovered in the area at Aislaby when drilling to look for oil. The reserves were investigated in the 1950s but appeared too deep to exploit economically. Solution mining was considered from 1962, but not pursued.
Imperial Chemical Industries (ICI) began construction on the mine in 1969, and started producing potash in 1973. The mine was the source of all of the UK's home-produced potash – around 55 percent of the total UK market. It occurs between 1.2 kilometres (0.75 mi) and 1.5 kilometres (0.93 mi) below ground and has an average seam thickness of 7 metres (23 ft). It took until 1984 for the mine to achieve profitability.
In April 2011, the mine began the world’s first commercial production of polyhalite, a rare mineral that has been found in large quantities in a seam out to sea from the mine, total resources estimated at over a billion tonnes lying more than 1.5 kilometres offshore. The mineral has a commercial potential as an organic fertiliser.
In April 2014, Cleveland Potash was awarded a £4.9 million government grant to support the mining of polyhalite at the Boulby site and parent company Israel Chemicals Ltd (ICL) has pledged to invest £300 million in the area before 2018.
Plans include extending the mine to the east and upgrading facilities to increase production capacity. Environmental groups have raised concerns that the development could have an intrusive effect on the local area.
Much of the output from the mine is transported by rail, as the site is located south of Loftus along the route of the former WRMU (Whitby Redcar and Middlesbrough Union Railway), which was closed on 5 May 1958. Today the line is open from Saltburn to Boulby for goods traffic only. Teesport handles most of the bulk cargo export from the mine, via a specific potash and rock salt terminal.
Because of its depth, Boulby Mine is used to house the ZEPLIN-III dark matter detector 1,100 metres below the surface in the Boulby Underground Laboratory. It also housed the UK Dark Matter Collaboration, and has served as a model for the Stawell Underground Physics Laboratory in Australia, which is of similar depth.
The mine also houses the Directional Recoil Identification From Tracks (DRIFT) detector, a low pressure negative ion time projection chamber (NITPC) designed to detect weakly interacting massive particles (WIMPs) – a prime dark matter candidate. There are currently two DRIFT detectors in operation. DRIFT-IIb, which is located 1100 m underground in the Boulby Underground Laboratory at the Boulby Mine in and DRIFT-IIc, which is located on the surface at Occidental College, Los Angeles, California, USA.
Health and safety
In June 2014, an employment tribunal revealed that the Boulby mine would have been unable to cope in an emergency. Former Rescue Team Coordinator Stephen Angus was fired after failing to ensure enough safety officers were trained to respond. He was also accused of failing to maintain the required standard of breathing apparatus.
Cleveland Potash Limited has been served with 11 notices for breaches of health and safety procedures by the Health and Safety Executive since 2012. They include not taking appropriate measures to protect workers from the risks of explosion, falling ground and inadvertent entry into the mine shaft.
In April 2014 there was a collapse one mile underground at the mine caused by a falling boulder. Two years earlier a 50-year-old man was airlifted to hospital after suffering chest injuries when a hose burst and forced him against a skip. In 2007, 24-year-old miner Darren Compton was killed by falling rock. He had been operating equipment supporting a sidewall in a recently mined roadway.
- Winsford – home of Britain's largest rock salt mine
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- Media related to Boulby Potash Mine at Wikimedia Commons
- Cleveland Potash Ltd
- Discovery Channel video from How Do They Do It?
- Boulby Potash Mine NZ761183, images at UK mine exploration website