That Time I Thought I Was Going to Die in a Slag Pit Explosion

I work at a steel mill. One of my jobs at said mill is to dig pits of red hot slag with a Caterpillar 988G Loader. If you are unfamiliar with steel mills or slag pits, I’ll give you a little background.

There a two basic types of still mills. Mills that make steel from iron ore using a blast furnace and mills the recycle old steel and turn it into new steel. The mill where I work does the latter. The furnaces that melt the steel are referred to as EAC (Electric Arc Furnace) Three very large electrodes are pumped with an ungodly amount of electrical current and the old steel is melted. Just to show you how powerful it really is, It only takes approximately 30 minutes to melt down enough scrap metal to produce 130 tons of 3000 degree liquid steel.

When melting down old scrap metal, a lot of impurities (items that are not steel) get melted along with the steel. These impurities are known as slag. The slag is dumped into a slag pot and then transported back to large pits dug into the ground. Each pit is dumped in for 12 hours, then allowed to sit and cool for 12 more hours (at this point the slag is solid, but still red hot) after which time it is dug by myself or one of our other Mill Loader Operators.

The most important thing to know about liquid steel is that it will explode if placed over water. Water can cover steel with no danger, however, if steel covers water, you get a massive explosion. It does not take much water to make a lot of steel explode. As a result of the slagging process, there is always a small amount of steel that gets into a slag pot. If there is a heavy rain, water will accumulate below the flooring of the slag pits. You can probably guess what happens when a pot full of liquid slag (mixed with a bit of steel) is dumped in a slag pit that contains water under the surface…that’s right, you get one hell of an explosion!

Personally, I love these explosions. There is nothing like hearing the loudest bang you could imagine and then seeing thousands of pieces of red hot slag propelled upward into the night sky. On the downside, pit explosions can (and sometimes do) cause fires. When the slag comes raining back down, nothing is safe. Not only is fire a hazard, but slag is like a very hard rock, and when it is coming flying at your window, it does not have much give. As a Mill Loader Operator you quickly learn the importance of keeping a safe distance when a slag pot is being dumped. Like most things in life, not all slag pit explosions are the same. Some are larger, some are smaller, and some seem to propel the slag in different directions.


I have seen many explosions during my time as a Mill Loader Operator, and have had my share of cracked windows due to out of control slag being propelled through the air at amazing speeds. Many times the explosions will create a hole in the ground about the size of a truck tire.

At approximately 8:15 PM on September 4th, 2008, slag pit #3 went above and beyond my expectations. As always I was keeping (what I thought was) a safe distance. I was parked near the west side of our debris pile. There had been a lot of rain recently, so I was ready for an explosion. Our Slag Pot Carrier Operator began dumping a slag pot. For the first few seconds, everything was cool, then it happened. Quite possibly the loudest slag pit explosion I have ever heard. Red hot slag filled the night sky, only this time it seemed like it was all heading straight for me!

Due to the large amount of water under the pit and the amount of liquid slag running down the the pit and into the water, by the time the Pot Carrier Operator realized what was happening and stopped dumping the pot, the pit exploded at least a dozen times more! It sounded like canon blasts at a symphony, a symphony of fire and brimstone straight from the bowels of hell itself! I backed away as fast as I could (which was about 5 mph, heavy equipment does not move very fast, especially when backing up from a dead stop), while red hot slag chunks, ranging in size from golf balls to bowling balls, began to rain down upon the 988G Loader I was occupying.

As I was backing away I was watching the slag chunks coming towards me, thinking to myself, “Is that one going to come through the window?!, Fuck!, I think it might!” Fortunately nothing came through the window, however the front windshield did suffer a couple of small cracks. Afterwords we checked our equipment and the surroundings. No significant damage and no fires. Things appeared to be alright.

Once I ventured back to the slag pit to see what was left of the area of impact, I discovered that the hole left in the pit was not the size of a truck tire, it was bigger than a person! It was so large, that I could have easily laid in the hole and not touched any of the surrounding slag in the pit! So let this be a lesson to you, just when you think you are safe from danger, you may be sitting right in the middle of it.


13 thoughts on “That Time I Thought I Was Going to Die in a Slag Pit Explosion

  1. That my friend is a good written article…I too myself am a pit loader operator for decatur mill service at nucor steel decatur alabama..I also run a 988G n I thoroughly enjoy my job….we have 3 pits here they usually aquire between 25 to 30 heats per pit…n wen it rains n the Kress carrier dumps in a freshly dug n padded pit…the results are usually awesome…I got a pretty cool video one night after a was like 14 explosions b4 the fire stopped flying…it was probably the best I ever saw…I been runnin this loader for 7 years n I have yet to witness another explosion of that magnitude…keep up the good work n keep it safe in those pits!!!

    • Thank you for the kind words!

      Although I no longer work in the steel/slag industry, I look upon my time spent in the seat of the 988G with fond memories. There’s something about big machines and big explosions that get the blood pumping. I would love to see your video footage of the explosions, perhaps it could be uploaded to In the past I have searched for images and videos of slag pit explosions, but to no avail. The steel/slag industry is like the Grand Canyon or Niagara Falls, no matter how many videos or pictures you see, there’s nothing quite like experiencing it in person.

      Thanks again, and you take care as well!

  2. I agree that your article is very well written and really interesting to an old 55 year old mom surfing the net to identify if the beautiful obsidian rock I found is only slag. I dont know if there ever was a mill or foundry or something where I found the rocks. But I sure enjoyed reading your story.

  3. i enjoyed reading your story before giving a class about fire watch. i think your story can be used to our trainees the danger of slag.

  4. Excellent article – I’m a steel mill fan and didn’t know that there was so much slag from an EAF – I’ve enjoyed watching blast furnaces but in the future I’ll try and see a slag drop from an EAF in my neighborhood – hats off to you!

  5. Very informative article for me as I work with a KRESS and a 988H same application as yours.
    But the question still remains, what can be considered as a relatively safe distance opposite to a slag pit? Please consider the fact that I belong and work in a country with comparatively high humidity and rainfall.

    • Thanks! It’s difficult to say what would be a safe distance. I typically stayed a few hundred feet back, but I’ve seen chunks of slag fly well over that distance. I’d recommend staying as far back as you can, and, as I learned from my experience, make sure you have room to back up in a hurry. 😉

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