CHENGDU, CHINA – Foxconn said it has resumed operations at its manufacturing plant here after an explosion killed three employees and injured 15 others last month.

An investigation into the cause is ongoing, but preliminary findings suggest an explosion of aluminum dust in a ventilation duct, according to published reports.

Foxconn says it has improved workshop ventilation and has revamped policies and practices related to dust disposal.

The factory builds iPad2 tablets for Apple, plus other electronics gear.