A fire shut down Nexa's zinc smelter. Here's what that tells us about supply risk.

By Siam Sukkhee Trading Co., Ltd — 2026-06-28 — zinc ingot supply demand

May 13. A fire at Nexa Resources' Cajamarquilla smelter in Peru. The kind of thing that makes you sit up because this isn't just any zinc plant.

It's the largest zinc smelter in the Americas, and it went down for weeks.

What struck me when I read through the sequence was how carefully Nexa had to choreograph the restart. Electrolysis first. Then casting. Then more casting. You can run the electrolysis lines all day and still have nothing to sell if your casting is offline. That's where the zinc becomes an actual ingot — something that trades, something that ships. Everything before that point is just laboratory work, more or less.

Seven thousand tonnes. That's what the fire cost them in Q2 output. About 2% of their annual production. They said they'd make it back in the second half, and the market believed them enough to bid the stock up 8.8%. Actually, that's not quite right — the market wasn't reassured by the fire itself. It was terrified the hole would be permanent. Everything else was noise.

Why this one smelter matters to everyone

Cajamarquilla sits outside Lima. It takes zinc concentrate and turns it into refined metal at a scale that, frankly, is difficult to replace on short notice. When 7,000 tonnes go missing from a single facility, the global zinc balance notices. The market doesn't shrug.

The zinc world runs on thin margins.

We're talking about relatively tight surpluses or deficits each quarter, so a swing that large from one site registers as an actual supply event, not corporate inconvenience. Refined zinc production globally isn't especially diversified — a handful of large smelters in China, Europe, and Latin America handle the bulk of it. When one of the bigger ones stumbles, the rest of the infrastructure can't absorb the gap quickly. Inventory buffers have been running lean enough that unexpected outages move prices. Traders recalculate. Contracts get nervous.

Here's what I found interesting about Nexa's approach: transparency and speed. The company disclosed the fire on May 13 and updated the market as each restart milestone cleared. They didn't let silence build up the uncertainty premium. Zinc traders generally priced the outage as temporary from the beginning, which meant the 2H26 recovery plan gave them a framework. Not mystery. Framework.

The cause remains under investigation, so Nexa hasn't said whether this was a maintenance failure or an equipment issue or something else altogether. A smelter that has recovered its casting lines is not the same as a smelter that has fixed the underlying problem. Something like that difference matters, even if the zinc is flowing again.

The real question nobody's answered yet

For zinc buyers downstream — galvanizers, steel producers on long-term contracts, people like that — this episode is another data point in a longer conversation about single-source risk.

Cajamarquilla is back.

But what happens if the next fire is bigger. Or the next outage lasts three months instead of three weeks. Or if it's not a fire at all.

Tags: Nexa Resources, Cajamarquilla, zinc ingots, Cajamarquilla smelter fire 2026, refined zinc supply disruption, zinc smelter restart Peru