A Delta Air Lines subsidiary has closed on a deal to purchase a suburban Philadelphia oil refinery so it can produce its own jet fuel.

The company closed on the $180 million purchase of the refinery in Trainer on Friday. A union official says workers are expected to start returning and getting the plant ready next week.

Delta announced in April that it would buy the idled ConocoPhillips refinery in a deal it hoped would cut its jet fuel bill by $300 million a year. Officials have said the refinery is expected to restart in September and that a Delta subsidiary -- Monroe Energy LLC -- will run it.

Denis Stephano, president of the local steelworkers union, says all of the workers who wanted to return are going back.

(Copyright 2012 by The Associated Press.  All Rights Reserved.)