China has ordered more than 2,000 factories to shut by next month because they are wasting too much energy.
The government described the outdated smelters and other processing plants as backward. It is unclear how many jobs will be lost.
The move is part of a broader plan for a substantial cut in energy use.
China overtook the US last year as the world's biggest energy consumer, but with a bigger population it is still well behind in consumption per person.
The figures were released by International Energy Agency.
The Ministry of Industry and Information Technology has published a list of 2,087 steel mills, cement works and other energy-intensive factories which it says must close by 30 September.
Energy analysts have described it as a significant step toward the country's energy-efficiency goals - which include a 20% reduction in energy consumption per unit of economic output, or energy intensity, by the end of the year.
A broader five-year plan suffered a setback this year as China's economic rebound created fresh demand for steel, cement and other energy-intensive products.
China is the world's largest steel producer and a major producer of other industrial materials.
Provinces that will be hardest hit by the closures are Henan in central China and Shaanxi in the north, which are traditional centres for heavy industry.