Boulby Mine

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. (ICL).

Boulby Mine
Surface workings at Boulby Mine
Boulby Mine
Location within the ceremonial county of North Yorkshire
LocationBoulby, Staithes
CountyRedcar and Cleveland
Coordinates54.5534°N 0.8245°W / 54.5534; -0.8245
Rock salt
ProductionPolyhalite 450,000 tonnes (500,000 tons)
Financial year2017–18
Greatest depth4,600 feet (1,400 m)[1]
Opened1968 (1968) shaft sinking
1973 (1973) first shaft production
1976 (1976) full production
CompanyIsrael Chemicals
WebsiteOfficial website

In early 2016, polyhalite mining commenced. Polyhalite (K2MgCa2(SO4)4·2H2O) is a natural multi-nutrient fertiliser providing a source of potassium, calcium, magnesium, and sulfur. It is marketed as Polysulphate by ICL and is sold in 3 grades: granular, mini-granular and standard.

As well as producing Polysulphate, a granulated blend of potash and Polysulphate is sold as PotashPluS - part of ICL's wider FertiliserPluS product spectrum.

It originally produced half of the United Kingdom'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).[2] The rock salt is extracted as a by-product and used across the region as a de-icing agent on roads in winter conditions. Other minerals are produced as waste (gangue) to the main effort, but may be sought after by mineral collectors, such as boracite, which occurs just above the beds of potash.[3][4][5][6]


In 1939, potash was discovered in the area at Aislaby when prospectors were 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.[7]

The first shaft was begun in 1968 and Imperial Chemical Industries (ICI) began construction on the mine in 1969, with potash from one shaft being produced in 1973. Full production of the mine did not commence until 1976.[8] 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 and 1.5 km (0.75 and 0.93 mi) below ground and has an average seam thickness of 7 m (23 ft). The mine did not achieve profitability until 1984.[2]

ICI formed Cleveland Potash Limited jointly with Anglo American, and later sold it to them, which in turn divested it to Israel Chemicals Ltd in 2002.[9]

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, with total resources estimated at over a billion tonnes lying more than 0.93 miles (1.5 km) offshore. The mineral has a commercial potential as an inorganic fertiliser.[10]

In April 2014, Cleveland Potash was awarded a £4.9 million government grant to support the mining of polyhalite at the Boulby site[11] and parent company Israel Chemicals Ltd has pledged to invest £300 million in the area before 2018.[12]

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.[12]

The mine had 1,001 employees in 2013[13] and can produce up to one million tonnes of potash each year.[14] 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.[15] Due to the mines' depth; it takes workers seven minutes travelling in a lift to reach the bottom of the mine.[16]

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.[13] In the 2017–18 financial year, the company made £92 million, down from £205 million from the previous financial year. During the same period they also incurred losses of £162 million due to an investment in ICL Iberia a sister company. Taking into account redundancies, impairment of assets and disposal of unrequired assets, the loss was adjusted to £38 million.[17]

By the end of 2018, the company had 470 employees after a round of job cuts related to the switch from mining potash to polyhalite.[18]

In 2018, the company was producing just over 450,000 tonnes (500,000 tons) of polyhalite with ambitions to more than double that amount to over 1,000,000 tonnes (1,100,000 tons) by 2020.[19]


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.[20] 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.[21]

Underground laboratory

Because of its depth, Boulby Mine is the site of the Boulby Underground Laboratory 3,600 feet (1,100 m) below the surface (2800 metre water equivalent). Part of the laboratory is called Palmer Lab (subterranean) and the laboratory's surface facilities are sometimes called the John Barton surface facility.

Work being carried out at the underground laboratory includes the UK Centre for Astrobiology study of extremophile organisms that can survive in a salt-rich environment.[22] The site is also used for testing NASA Mars rovers.

In October 2017, the European Space Agency (ESA) sent astronaut Matthias Maurer as part of the fifth Mine Analogue Research sortie. It is thought that the brines present in the mine may be able to support extremophiles, and be like similar sites in caves on other planets.[23]

As of 2019,[24] extant testing and recording programmes at the laboratory include:

  • BUGS or BUGs (Boulby Underground Germanium Suite; also used to be called Boulby-Ge): Ultra-low background material screening of Germanium for development of dark matter experiments
  • UltraLO-1800 equipment: For study of radioactivity of the surface layers of materials (surface screening) with aim to aid in development of dark matter experiments
  • SELLR (Subsurface Experiment of Life in Low Radiation): an experiment studying the effect of low-radiation environment to biological systems
  • Deep Carbon, MuScan, Muon-Tides (3 experiments): Muon Tomography
  • DRIFT-II (Directional Recoil Identification From Tracks):[25] dark matter experiment. One of the experiments detectors, the DRIFT-IIb, is located at Boulby. A low pressure negative ion time projection chamber (NITPC) designed to detect weakly interacting massive particles (WIMPs, a prime dark matter candidate), a second detector (DRIFT-IIc) is located on the surface at Occidental College, Los Angeles, California, USA.[26]
  • BISAL (Boulby International Subsurface Astrobiology Lab): Geomicrobiology / Astrobiology studies
  • MINAR (MINe Analogue Research): Space exploration technology development

There are also concurrent geological and geoscience projects ongoing.[27][28]

Previous, now completed experiments include:

Proposed experiments (as of 2019) include the WATCHMAN (WATer CHerenkov Monitoring of ANtineutrinos, also called AIT/WATCHMAN) neutrino experiment, which would study antineutrinos originating from Hartlepool nuclear power plant. This project would aim to develop technologies to remotely monitor nuclear reactors for the purpose of nuclear non-proliferation.

Health and safety

Since the year 2000, there have been several incidents at the mine. Cleveland Potash Limited has been served with 11 notices for breaches of health and safety procedures by the Health and Safety Executive since 2012.[30] They include not taking appropriate measures to protect workers from the risks of explosion, falling ground and inadvertent entry into the mine shaft. Other incidents include;

  • 2001 – an electrician was hospitalised after receiving severe burns to his face during routine maintenance work.[31]
  • 2003 – a lorry driver was airlifted to hospital after being trapped underneath a vehicle for over an hour whilst working underground.[31]
  • 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.[31]
  • 2012 – a 50-year-old man was airlifted to hospital after suffering chest injuries when a hose burst and forced him against a skip.[32]
  • April 2014 – there was a collapse at the mine caused by a falling boulder.[33]
  • June 2014 – an employment tribunal revealed that the Boulby mine would have been unable to cope in an emergency. A former rescue team coordinator 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.[34]
  • 13 April 2016 – a fire broke out underground requiring seven workers to be hospitalised for smoke inhalation. Polystyrene blocks had caught alight 3,600 feet (1,100 m) under the sea and 5 miles (8 km) from land.[35]
  • 17 June 2016 – a miner, 55-year-old John Anderson, was killed in a "gas blow-out" while working in the mine.[36]

See also


  1. "The World's Only Polyhalite Mine | ICL Boulby". Retrieved 8 January 2019.
  2. "Boulby, United Kingdom",, Progressive Digital Media Group PLC. Retrieved 11 November 2014
  3. "Subterranea Britannica: Sites:Boulby Potash Mine". Retrieved 8 January 2019.
  4. "Yorkshire – Steetley Minerals". Retrieved 8 January 2019.
  5. "Boracite" (PDF). Retrieved 8 January 2019.
  6. Milne, John K; Saunders, Michael J; Woods, Peter J E (September 1977). "Iron-boracite from the English Zechstein". Mineralogical Magazine. Vol. 41 no. 319. London: Mineralogical Society. pp. 406–406. ISSN 0026-461X.
  7. Paul Sowan. "Boulby Potash Mine – a site visit". Subterranea Britannica. Retrieved 27 April 2013.
  8. BGS 2011, p. 2.
  9. ICL Fertilizers. "Boulby Potash Mine, United Kingdom" (PDF). Retrieved 27 April 2013.
  10. "A new mineral and new jobs at Boulby mine". The Guardian. 12 April 2011.
  11. "Potash mine given £4.9m cash boost". BBC News. 10 April 2014. Retrieved 8 January 2019.
  12. "Potash plant to create 270 jobs". BBC News. 16 April 2013. Retrieved 8 January 2019.
  13. "Cleveland Potash Continues Investment After Turnover Growth". 13 October 2013. Retrieved 18 November 2013.
  14. "Huge grant just the job at Boulby". Whitby Gazette. 15 April 2011.
  15. Inside the potash mine one mile under the North Sea, BBC News, 24 April 2013.
  16. Farmer, Ben (17 June 2016). "Man dies after gas blast at Boulby mine". The Telegraph. Retrieved 8 January 2019.
  17. Manning, Jonathon (3 August 2018). "Operators of Boulby Mine suffer £161m loss after traumatic year". Gazette Live. Retrieved 8 January 2019.
  18. "PM 'support' pledge for axed potash mine". BBC News. 10 January 2018. Retrieved 8 January 2019.
  19. Breen, Julia (9 August 2018). "Jobs secure as Boulby mine stops potash production after 45 years". The Northern Echo. Retrieved 8 January 2019.
  20. Bairstow, Martin (2008). Railways around Whitby volume 1 (3 ed.). Farsley: Martin Bairstow. p. 111. ISBN 978-1-871944-34-1.
  21. BGS 2011, p. 6.
  22. Rebecca Morelle (7 August 2013). "Boulby mine: Underground life gives alien clues". BBC News.
  23. Mine craft for Mars,, 23 October 2017
  25. Paling, Sean (21 July 2016). Boulby Underground Laboratory: Status and plans. Identification of Dark Matter 2016. Sheffield. Archived from the original on 21 August 2016. Retrieved 12 August 2016.
  26. "Boulby Underground Laboratory". Science & Technology Facilities Council. Archived from the original on 16 October 2013.
  27. Meehan, Emma. "Deep Science at Boulby Underground Laboratory" (PDF). Retrieved 8 January 2019.
  28. Gullon, Nick (10 October 2017). "World scientists gather at Boulby mine for science project". The Northern Echo. Retrieved 8 January 2019.
  29. Mitchinson, James, ed. (5 January 2019). "A path to the stars from deep below Whitby". The Yorkshire Post. p. 9. ISSN 0963-1496.
  30. "Notices found for Cleveland Potash Limited". Health and Safety Executive. Retrieved 18 November 2014.
  31. "Probe into potash mine tragedy". The Northern Echo. 21 April 2007. Retrieved 8 January 2019.
  32. "Worker hurt underground at mine". BBC News. 19 January 2012. Retrieved 8 January 2019.
  33. Robson, Dave (8 February 2014). "Probe after a 'collapse' deep under Boulby potash mine". Gazette Live. Retrieved 8 January 2019.
  34. "Sacked Cleveland Potash worker's behaviour 'endangered lives of hundreds', tribunal hears". Gazette Live. 4 June 2014. Retrieved 8 January 2019.
  35. "Fire-hit mine to face no further action". BBC News. 11 October 2017. Retrieved 8 January 2019.
  36. "Identity of Boulby mine death victim revealed". ITV News. 17 June 2016. Retrieved 8 January 2019.


  • British Geological Survey (2011). Mineral Profiles: Potash (PDF) (Report). Keyworth, Nottinghamshire: British Geological Survey. Retrieved 8 January 2019.
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