KAUKAUNA, Wisconsin -- An explosion on Saturday, 6 Sept 2014 at Expera Specialty Solutions' Kaukauna mill injured a worker and caused approximately $500,000 in damage, according to news reports.

Expera released a statement that said an automatic isolation valve malfunction allowed hot gas to connect with coal dust which caused the blast.

It reportedly took firefighters nearly an hour to extinguish the flames caused by the explosion. The injured employee was treated at the scene.

Expera Specialty Solutions was formed by the 2012 merger of Thilmany Papers and former Wausau Paper mills.