Phil Baines, managing director at Cleveland Potash, in Boulby, east Cleveland, is moving to work in Ethiopia.
Bosses say Mr Baines will oversee a $1bn low-cost potash development in Dallol, in the north-east of the country.
The company refused to comment on reports it has lost £7m in the last six months.
Mr Baines is expected to leave his role next month, with the firm saying the move is part of a wider restructure.
Earlier this year, Cleveland Potash, which employs 1,100 workers, was awarded £4.9m from the Government’s Regional Growth Fund to support a £38m project focused on mining and processing the fertiliser mineral polyhalite.
The company said it will create 125 direct jobs and about 265 indirect posts, helping to secure the long-term future of the mine, which has a 1,100-strong workforce and is the biggest employer in east Cleveland.
At the time, Mr Baines said there was great potential to sell hundreds of thousands of tonnes over the coming years.
Speaking about his move, a spokesman for Israel Chemicals Limited (ICL), Cleveland Potash’s parent company, said: “ICL has embarked upon a significant restructuring programme to make it more efficient and competitive in the global market place.
“Within this programme, Cleveland Potash has joined the wider ICL family and a rebranding process will result in a new company name and logo for Cleveland Potash, which will become ICL Fertilizers.
“As part of ICL’s global expansion strategy, Phil Baines has been given the opportunity to lead a major global development, which is a potentially $1bn scheme in Dallol.
“Phil has been asked to take on this huge challenge because of his extensive managerial, mining, and engineering experience, which made him the perfect candidate and we wish him all the best.
“In his place we welcome David Zvida, who is relocating to the UK and joins us from his post as senior vice-president of operations at ICL’s Dead Sea Works.
“We are very much looking forward to David joining our team and to the exciting times ahead.
“Over the last 18 months, Cleveland Potash has strengthened its workforce and ICL has invested heavily in our operations in an effort to secure a sustainable business.”
Earlier this year, The Northern Echo revealed Cleveland Potash could move jobs to Amsterdam, with bosses considering plans to switch some back office roles to the Dutch capital.
The changes are being looked at by ICL, which wants to centralise work across its subsidiaries to maintain its global expansion.
The firm said up to 35 roles could be affected in human resources, purchasing and finance posts.
However, a spokesman said it expects any changes to only affect up to 20 per cent of that figure, and hopes to retrain a large number of staff in new roles.
Any decision could take up to two years.