Labourers filter coal out of cinder at a dump site of the Xilutian coal mine on the outskirts of Fushun, Liaoning province July 15, 2009. Some of China's small coal mines are returning to production as the country enters the hottest time of the year, releasing some of the tightness in the market caused by efforts to tighten safety by shutting small mines, industry officials and analysts said on Tuesday. REUTERS/Sheng Li (CHINA ENERGY BUSINESS)