Friday update:
Algoma Steel announced Friday that all five of its employees who were sent to hospital following this incident were treated and released.
Another seven workers were "impacted" but not treated at hospital.
The company said the incident occurred at the north casthouse of Algoma's blast furnace complex, where slag is believed to have made contact with moisture in a hot iron trough.
“The hazards associated with working with molten metal are well known to us and we have comprehensive training and procedures to ensure the safety of our operations," said Michael Garcia, Algoma's chief executive officer.
"Our investigation is ongoing to fully understand what happened. Our first and primary concern is the health and safety of our employees and we are thankful for the rapid and professional response of our first responders," Garcia said.
Thursday coverage:
Algoma Steel Group advises SooToday that five of its employees were treated at Sault Area Hospital following a frightening explosion Wednesday night at #7 blast furnace.
"I confirm that the incident depicted on the video is at the north casting troughs of our blast furnace around 10 o'clock," said Laura Devoni, the steelmaker's director of corporate affairs and sustainability.
"It appears that there's an eruption of slag in the trough," Devoni said.
"We are investigating the circumstances and the root cause to ensure that we minimize and prevent these types of events in the future."
"That's all I can really say at this time because we're looking to better understand what happened and we do want to respect the privacy of our employees who were involved in the incident," she said.
The blast furnace was temporarily taken out of service following a collapse of utilities piping Jan. 20, which could end up potentially costing the Sault steelmaker upwards of $30 million.
Devoni said the work of bringing the blast furnace back to full production remains on schedule, with usable hot metal produced within the next five days, and a return to full production expected within the next two weeks.
"That schedule is still the same," she said.
Devoni wasn't immediately aware of the status of the five employees treated for burns, but a union source with knowledge of the situation said most were released from hospital.
The Ministry of Labour, Immigration, Training and Skills Development advised SooToday on Thursday that it had not been notified about the incident.
Devoni, however, said the labour ministry was notified on Thursday morning.