* Salvage going to plan, hulk due to depart July 21
ROME, July 15 (Reuters) - Engineers were securing the final chains to the Costa Concordia on Tuesday, preparing the wrecked luxury liner to be towed away from the Italian island where it sank two and half years ago, killing 32 people.
The 114,500 tonne Concordia ran aground off Giglio island in January 2012 and has been stranded there ever since as engineers set up one of the biggest maritime salvage operations in history.
Now the rusting hulk of the once-gleaming white ship, more than twice the size of the Titanic, is on course to leave the Tuscan coast on July 21, engineers said at a press conference.
"Work has proceeded all night, still 4 chains to be connected," the wreck removal project organisers said on their official Twitter feed at around midday.
The vessel, which struck rocks after sailing too close to the shore, was righted in a complex "parbuckling" operation last September, leaving it resting on an underwater platform.
On Monday, air was pumped into 30 large metal boxes, or sponsons, attached around the hull. The air forced water out of the sponsons, lifting the boat 2 metres off the platform.
Tug boats then heaved the boat - owned by Costa Crociere, a unit of Carnival Corp about 30 metres from shore, readying it to be towed north to Genoa to be broken up for scrap.
The ship's captain, Francesco Schettino, is on trial accused of manslaughter, causing a shipwreck and abandoning ship. He is fighting the charges. (Reporting by Isla Binnie; editing by Ralph Boulton)