In 1967, the steelworks were nationalised to become the British Steel Corporation, later privatised as British Steel, which in 1999 merged with Dutch company Hoogevens to become Corus.
Hundreds of workers took voluntary redundancy or early retirement, while thousands more were made redundant over the years.
Corus was bought by the Indian conglomerate Tata in 2007.
Though iron ore is no longer mined in the North East, it is shipped to the facility from around the world.
Teesside Cast Products employs about 2,000 people, and is a lynchpin for many local suppliers.
Mark Hannon, cabinet member for economic development at Redcar and Cleveland Council, said: "Manufacturing at Corus is the heart of Teesside. These are well-paid jobs the likes of which we cannot afford to lose.
"The domino effect on all the industries that support it will be quite horrendous for the area.
"We could be talking about up to 8,000 more jobs outside of Corus - it's that bad."
There is some hope however, in the shape of a burgeoning renewable energy industry which utilises the skills of ex-steel and chemical workers.
Thirty years ago, the plant was originally sold off to various foreign owners who failed in their responsibility to the workers of Corus
Mark Hannon Redcar and Cleveland Council
A £300m bioethanol plant has been built at Wilton and planning permission has been given for a £200m recycled wood burning 50MW power station at Billingham.
Alan Clarke, chief executive of regeneration agency One NorthEast, said: "The skills and experience developed in the area will be invaluable as we strive to capture opportunities in the low carbon sector and emerging new sustainable areas such as bio-energy, logistics, oil and gas and the offshore industry in the Tees Valley."
But Mr Hannon said the local green industry needed to develop further before it could provide sufficient employment in the area.
"Our economy is built on the manufacturing of chemicals and steel and that has all been hit by the global recession," he said.
"All that goes into places like the car industry, which has also been hit.
"We're going to end up losing a lot of people and end up with an ageing population that doesn't work.
There are more than 2,000 Corus employees on Teesside
"I do put my faith in the renewable energy but it needed to be in place now to soak up what we've lost."
He added: "Thirty years ago, the plant was originally sold off to various foreign owners who failed in their responsibility to the workers of Corus.
"They are not going to push the boat out to save something that's not in their backyard."
Council leader George Dunning said: "I want to emphasise that Redcar and Cleveland Council will be urging government to put into action swift measures to mitigate these massive job losses."
A Corus Response Group, made up of representatives from organisations including the council, JobCentre Plus, and One NorthEast, as well as Redcar MP Vera Baird, has developed a package of support since it was set up 10 months ago.
It says on-site employment experts will help workers, highlight job opportunities and look at re-training options.
The group will also be working closely with those businesses that supply Corus to offer similar support.
Anyone affected by the job losses can call 01642 398975.
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