China’s steelmakers face their biggest crisis in years, with demand frozen as factories and construction sites fall silent. But they’re still churning out metal. The collapse in economic activity amid China’s unprecedented measures to contain the coronavirus outbreak means there are few buyers of steel, which has sent prices tumbling and put margins under intense pressure. However it’s difficult for most steelmakers in China to cut output drastically because blast furnaces are designed to run constantly, and reducing production to zero is usually a last resort. The result is millions of tons of steel piling up at mills.