There's an answer to this. Nationalisation.
Stage 1: Nationalise it. Pay Ineos the very lowest end of a fair market price, obviously taking into account a cold refinery, a closed petrochemical plant, a hostile union, their claims of massive ongoing losses and so on. Do you think £1 would be too much?
Stage 2: De-power the unions who'd quite happily kill the plant to get their way by creating a John Lewis style co-operative Partnership. A few idiot moves by unions that cost the company lots of money and, by association, reduce the money going into employees' hands via profit shares will see them shown the door.
So, when you've nationalised it and made choosing not to work illegal, all in the name of national security. Which other vital services will you want to remove workers rights from? Nurses? Teachers? etc