140 more jobs to go at Boulby - but owners want to mine there for another 40 years

Owner ICL said the move at the Boulby mine, near Staithes, reflected the “continuing decline” in potash prices.

The latest job losses come on top of 220 redundancies and the removal of 140 contractor posts announced last November.

But ICL also said it wanted to extend its licence to mine at the site for another 40 years, by switching from potash to the extraction of another fertiliser, Polysulphate.

Its current licence runs out in 2023, and an extension requires approval from the North York Moors Park Authority.

Peter Smith, ICL’s executive vice president for potash, said the Boulby plant would be “restructured” around the extraction of Polysulphate, while its limited remaining reserves of potash would continue to be mined at a reduced rate until exhausted.

He said Boulby would remain “a significant employer in the area”, but added: “When we announced the restructuring of the business last November we made it clear that, given the very limited level of economically feasible potash reserves, we had to move our focus to Polysulphate production.”

He said the company was developing a range of fertiliser products based on Polysulphate, as well as a compacted potash and Polysulphate product to be marketed as PotashpluS.

Mr Smith added: “The restructuring, although difficult, is aimed at ensuring that ICL UK has a future as a supplier of world-class products for many years to come, which is underlined by our decision to submit an application to the North York Moors Park Authority to extend our planning approval for a further 40 years.”

Boulby, which employs around 1,000 people, has been hit by a series of tragedies since last November’s redundancies.

In June, a worker was killed in an underground explosion while the plant was on a heightened state of alert over gas escapes.

John Anderson, 56, died when a sudden release of gas occurred in the section where he was working.

Earlier this month, a contractor was airlifted to hospital after suffering burns in an incident at the site.

He was flown by air ambulance to a specialist burns unit at Newcastle Hospital.

In April this year, seven miners were rescued by the underground mine rescue unit after a fire broke out in supposedly fire-retardant polystyrene blocks used to circulate air around the mine.

And in 2014, the Mines Inspectorate was called in after a serious roof collapse underground.

Mr Smith insisted that safety at the site was a “top priority”, and added: “We are having to make operational changes reflecting the limited areas where we can economically mine whilst maintaining our commitment to ensure that we place safety as our top priority.”

Boulby is the world’s only producer of Polysulphate, which is claimed to be more environmentally friendly than other fertilisers and contains four plant nutrients of sulphur, potassium, magnesium and calcium.