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).
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). 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.
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.
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. 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.
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.
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 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.
The mine had 1,001 employees in 2013 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. Due to the mines' depth; it takes workers seven minutes travelling in a lift to reach the bottom of the mine.
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 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.
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.
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.
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 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. 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.
As of 2019, extant testing and recording programmes at the laboratory 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.
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. 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;