By KEVIN NEVERS

Five of the seven Mittal Steel USA employees injured on Tuesday when a fireball erupted from the No. 1 vessel at the Burns Harbor facility’s basic oxygen furnace remained hospitalized in Chicago today.

The most seriously injured, Dennis Baltzer, 55, of Valparaiso, was in critical condition, Paul Gipson, president of United Steelworkers Local 6787, told the Chesterton Tribune this morning.

In critical but stable condition were Jack Ballantine, 56, of Valparaiso; Jeremy Schoon, 30, of Lake Village; and Michael Hardin, 56, of Demotte. In serious but stable condition was Charlie O’Brien, 57, of Westville.

These five employees and two others were standing on the other side of a barrier wall during the “tapping” or emptying of the No. 1 vessel when a fireball erupted during a “squish” or “burp,” a chemical or metallurgical reaction in which a quantity of molten steel is expelled. Gipson said that the seven employees were burned not by the molten steel but by the fireball, which “came flying out of the top of the vessel” and bounced off and wrapped around the barrier wall.

The cause the squish is still under investigation and may be for weeks, Gipson said, but one theory has already been rejected, namely, that the briquettes–the 3,500 pounds of powdery “fines,” along with 5,000 pounds of burnt lime, added to the molten steel just prior to the squish to drop the temperature of the molten steel–might have been contaminated. In fact those briquettes were found not to be contaminated, Gipson said.

Instead investigators have turned their attention to the “skull” of the No. 1 vessel, a buildup of slag and residue around the top and the bottom. It’s possible, Gipson said, that a piece of the very heavy skull may have broken off the No. 1 vessel and dropped into the molten steel, generating a kind of “tsunami”–the squish itself–and for a reason not yet understood the resulting fireball.

Why a piece of skull may have been dislodged from the No. 1 vessel–if indeed one was–is unclear, although Gipson thinks it could have something to do with the temperature of the molten steel, which had exceeded the ideal temperature of 3,010 degrees Fahrenheit by more than 200 degrees. That high temperature, which had begun to cause an unstable “foaming action” in the molten steel, originally prompted the addition of the briquettes and burnt lime. Conditions had returned sufficiently to normal, however, to convince the employees that it was safe to begin tilting the No. 1 vessel to tap it when the squish occurred.

Gipson repeated his belief, stated on Wednesday, that at this point negligence would not appear to have been a factor in the accident. “Is this one of those unusual Murphy’s Law things? I don’t think anyone was negligent,” he said. “I think everyone did their job.”

But, Gipson added, the barrier wall itself may have significantly contributed to the employees’ injuries. As it happens, the barrier wall is relatively newly constructed but has nothing to do, strictly speaking, with worker safety. Rather it was designed and installed to protect a large vacuum system intended to remove airborne particles and contaminants and prevent their entering the atmosphere.

But the barrier wall may have prevented the fireball from dropping immediately into a slag pit directly beneath the No. 1 vessel, Gipson ventured, giving the flame surfaces to ricochet off of and bounce around.

That barrier wall may need to be redesigned, Gipson said, with some sort of system of movable or sliding doors to provide a sort of venting or voiding area for future squishes.

Posted 8/30/2007