Hundreds of jobs are to go at Boulby Potash Mine in East Cleveland, the company has confirmed this morning.
Cleveland Potash is Europe's deepest potash mine and produces and supplies potash fertilisers for agriculture and industry.
It employs around 1,100 people and today's announcement has said that 350 jobs are to go immediately.
Consultation has begun on 220 job losses amongst its employees and there will be a reduction of 140 contractor numbers.
The company unveiled a "significant restructuring" of its operations including moving from producing potash to polysulphate fertiliser.
Peter Smith, executive vice president, said the restructuring, although "painful", was vital to secure the future of ICL UK as a viable business.
Around 2,000 jobs were lost on Teesside earlier this year with the liquidation of SSI.