Fushun, a city built on coal in China’s industrial northeast, is in full-blown recession. Liu Junfen, a scrap-metal merchant who gathers discarded bicycles, hubcaps and gas cylinders to feed to local steel furnaces, says that prices have plunged by two-thirds since China’s overbuilt real-estate market took a dive in 2014—if she can find buyers for her junk at all. As for this year’s prospects—“Gou qiang,” she sighs, an expression…