Ironton firefighters spent much of Friday removing 600 tons of sawdust that caught fire Thursday afternoon in a silo at Muth Lumber.

Mark Muth, co owner of the lumber business, said he hoped to have the silo emptied, sprayed down and then reloaded for use soon. The sawdust, which is a byproduct of Muth’s lumber process, is also stored and burned to heat water for the boilers that fire the kilns at the plant.

“It’s a very green way of running the kilns,” Muth explained.

The fire was discovered Thursday afternoon when workers were getting ready to install a new piece of equipment and noticed the smoke in the silo.

The new equipment, incidentally, will grind larger blocks of scrap wood into sawdust to allow the lumber company to better recycle scrap wood.

Capt. Craig Thomas said it is not known what caused the fire and said it is possible for sawdust to combust spontaneously but did not know if that was the case with this fire.

Firefighters worked until approximately 10 p.m. Thursday but the fire reignited and they were called back to the silo. The decision was made Friday to clear all of the sawdust out of the silo until the fire was completely extinguished.