Latest / The Manufacturing Podcast with Fexingo: Factories, Supply Chains, and Industrial Business / How a Factory in Ohio Is Making Steel From Old Tires
Transcript
- Lucas: So I was reading through the EPA's latest scrap tire report, and there's a number in there that just stopped me. In 2024, American steel mills consumed something like 40 million scrap tires a year as a supplemental fuel in their blast furnaces. Luna: Forty million tires — going into steel furnaces. I had no idea that was even a thing. Lucas: Right, and it's not some fringe experiment anymore. There's a plant in Ohio — a family-owned steel company, I won't name them — that's been running on a blend of coal and tire-derived fuel for over a decade. They feed shredded tires directly into the blast furnace, replacing maybe 15 to 20 percent of the coke they'd normally burn. Luna: So the tires aren't just getting melted down, they're actually acting as a fuel source. Is that the idea? Lucas: Exactly. A tire is mostly rubber, which is essentially hydrocarbon — it's got a higher BTU content per pound than coal, believe it or not. So you grind it up, strip out the steel wire, and what's left is a fuel that burns hot and consistent. The steel wire gets recycled separately, and the zinc from the rubber ends up in the dust, which can be recovered and sold. Luna: I remember a few years ago there was a scandal about tires being dumped illegally in the Midwest. So using them in furnaces kind of solves that problem too, right? Lucas: That's the irony. For decades, scrap tires were an environmental headache — stockpiles catching fire, breeding mosquitoes. Now, the steel industry has become a major sink for them. The EPA estimates that around two-thirds of all scrap tires in the U.S. now get burned as fuel, and steel mills are the largest industrial consumer. Luna: But is this actually cleaner than just burning coal? I've seen skeptics argue it's just greenwashing by the steel industry. Lucas: It's a fair question. The steel industry is responsible for about eight percent of global carbon emissions, so any reduction matters. But the chemistry isn't simple. When you burn tires, you get emissions of things like zinc oxide and sulfur — though modern scrubbers handle those. The carbon footprint is actually lower because tires are a waste product — you're not extracting new carbon, you're reusing what's already there. Luna: So it's like a two-for-one: you avoid the emissions from producing coke, and you deal with the tire waste. Lucas: Right. And the economics have shifted. Coke prices have been volatile, especially after the Ukraine war, and tire-derived fuel is often cheaper per BTU. That's why some plants are now blending up to 25 percent tires without major retrofits. Luna: Wait, so what's the catch? If it's cheaper and cleaner, why isn't every mill doing it? Lucas: There are a few headaches. First, the tire wire — even after shredding, you get steel filaments that can clog the furnace's tuyeres, the pipes that blow in hot air. So you need a really good separation step. Then there's the zinc. Tires contain about two percent zinc, and in the furnace, it gets into the dust, which can foul the gas recovery system. Some plants have to invest in special dust treatment to handle that. Luna: So it's not a simple drop-in replacement. You need to adapt the process. Lucas: Exactly. That's why you see the big integrated mills — the ones with blast furnaces — being the ones to do it, because they have the environmental controls and the scale. Smaller mini-mills use electric arc furnaces, which don't burn fuel the same way, so they can't use tires. Luna: So it's really a niche within a niche. But the fact that it's growing — what's the trajectory? Lucas: The growth is steady, not explosive. In 2010, maybe five percent of scrap tires went to steel mills. Now it's more like 12 percent. And it's not just the U.S. — Canada, Japan, Europe all have similar programs. There's also interest in using tires as a reductant, not just a fuel — the carbon in the rubber can help reduce iron ore, which is the actual chemical job of coke. Luna: Huh. So it's not just about heat, but also about the chemical reaction that turns iron ore into iron. Lucas: Precisely. Coke does double duty: it's both the fuel and the source of carbon monoxide that strips the oxygen from the ore. Tires, being hydrocarbon, can contribute to that reduction process too. That's why some engineers think the substitution rate could go higher, maybe up to 30 percent, with the right pre-treatment. Luna: I've also heard about something called 'tire pyrolysis' — heating tires without oxygen to get oil and carbon black. Is that a competing technology? Lucas: It's a different route, and it's been struggling commercially. The output oil is poor quality, and the carbon black needs a lot of processing to be usable. By contrast, feeding tires directly into a blast furnace is proven, cost-effective, and has been around since the 1970s. Luna: So the old-school approach is winning because it actually works at scale. Lucas: Right. And here's a concrete example: the Ohio plant I mentioned — they process about five million tires a year. That's roughly 30,000 tons of tires, displacing about 20,000 tons of coal. Over a year, that's a meaningful cut in their carbon footprint, and it keeps those tires out of landfills. Luna: And that's just one plant. If a dozen more did the same, that's tens of millions of tires a year. Lucas: Exactly. Now, I should be clear — this isn't some silver bullet. Steel is still a heavy-emitting industry, and the real future is in things like hydrogen-based DRI, which we covered a while back. But tire-derived fuel is a bridge. It's something you can do today, with existing furnaces, without a billion-dollar investment. Luna: It's a pragmatic step. And I like that it's a win-win — cheaper for the mill, and a waste product gets a second life. Lucas: And on the waste side, the numbers are staggering. The U.S. generates about 280 million scrap tires a year, and historically, a huge chunk ended up in illegal dumps. Now, with steel mills and other industries burning them, the stockpiles have shrunk dramatically. The EPA says the number of tires in stockpiles has dropped from over a billion in the 1990s to under 60 million today. Luna: That's a huge environmental win, even if it's not the headline-grabbing tech. Lucas: Yeah. And you know, this episode wouldn't be happening without the support of our listeners. If these conversations have moved your work forward in some small way, a couple of dollars a month is genuinely what keeps these going — buy me a coffee dot com slash fexingo, if you've gotten something out of them. It's a small gesture that makes a real difference to us. Luna: Yeah, and it's because of that support we can keep digging into stories like this one. It's not always flashy, but it's the stuff that matters. Lucas: So back to the tires — one thing that surprised me is how the industry is actually getting creative with the ash. The residue from burning tires contains zinc, which is a valuable element. Some mills are now partnering with zinc refiners to recover it from their dust. That's another revenue stream, and it closes the loop even further. Luna: So you get steel, you get zinc, and you get rid of a waste problem. That's a pretty nice trifecta. Lucas: It is. And it's a reminder that in manufacturing, sometimes the smartest innovations aren't about building something new — they're about looking at your waste stream and seeing an input for someone else's process. Luna: Well, and here we are, talking about tires in blast furnaces. Who'd have thought? Lucas: Right? It's these unexpected connections that keep this beat interesting. Next time you see a pile of tires at a recycling center, you'll know where a good chunk of them are headed.