In 2011, molten metal escaping the shell of a furnace caused an explosion in AK Steel's Butler plant. Seven years later, a jury will soon be selected to determine who is responsible.

The steel manufacturer claims that a company called Magnesita Refractory, which was using the steel plant to process metals, is behind the incident.

In court filings, AK Steel officials claim that a Magnesita employee failed to notice that there was a problem with an electric arc furnace after he inspected the lower shell over a water leak and decided that it was in good enough condition to “make 70 more heats,” according to court documents.

An electric arc furnace gets its name from the source of energy it uses to heat up charged materials in a cauldron-shaped device. Furnaces can reach very high temperatures needed to melt metals down to liquid form.

Representatives for both companies declined this week to comment on the case.

The oozing metal didn't hurt anyone, but the resulting explosion caused damage to the furnace and the plant, according to court documents.