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.

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 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.

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.

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

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