The supply of copper is usually associated with the image of huge open pit mines in Chile and elsewhere. But there is a lot more beyond the dirt of the excavations.

The so-called “urban mine” – copper scrap – supplies a quarter of the world’s consumption of the red metal, much more than any single country, including Chile. Lured by record high prices, scrap supplies had been readily available in recent years to feed voracious demand in developing countries, particularly from China. But not any longer.