The visible emission was from the Blast Furnace’s “bleeder valve” and lasted 12 seconds. “Bleeders” are a safety mechanism: Pressure relief valves that open when high top pressure is experienced at the furnace.
The emission would have been comprised of primarily carbon monoxide and carbon dioxide and nitrogen. Any particulate in the emission is iron, ore fines, coke fines, carbon and coal.
The Ontario Ministry of Environment, Parks and Conservation’s Spills Action Centre has been alerted and our teams are investigating.