This is the official statement from Changi Airport:
An A380 Qantas flight, QF 32, bound for Sydney, Australia, departed Singapore Changi Airport at 0956 hours today. For technical reasons, the aircraft turned back to Changi and landed safely at 1146 hours.
Changi Airport Group's Airport Emergency Service (AES) responded with six fire vehicles, in accordance with standard operating procedure for such incidents. In response to the pilot's request, checks were conducted on the aircraft by AES. Once the checks were completed, passengers and crew began disembarking from the aircraft at Runway 2. Buses were arranged to ferry them to the airport terminal. Disembarkation of all 469 passengers and crew on board was completed by 1340 hours.
Runway 2, which has remained closed since the landing, will reopen later today. Flights have continued to take off and land at Runway 1 and operations at Changi have, otherwise, not been affected.
Assuming the explosion occurred 10-15mins into the flight, it took about an hour and a half to defuel and prep for landing. Must have been scary for the pax for such a long time.
Then, it took almost 2 hours (!?) to get everyone off the plane. Note they did not launch the emergency slides.