They used bellows-equipped shaft furnaces and two procedures, namely "oxidized ore to copper" and "sulphide ore to matte to copper," thereby precisely controlling furnace temperatures at around 1,200 degrees Celsius.

　　At the time, crude copper reached a purity of 93 percent, while the copper content in slag was just 0.7 percent, which is a level far ahead of the rest of the ancient world, with some techniques approaching near-modern standards.

　　Mining and metallurgical activity at Tonglushan never really stopped, and by the late 19th century it was home to what was then Asia"s largest integrated iron and steel enterprise, while production further expanded after the founding of the People"s Republic of China in 1949.

　　"Today, copper production here has moved into higher-value processing, serving fields such as new-energy vehicles, 5G communications and semiconductor chips," said Pan Xiaojin, mayor of Daye.

　　Daye has also expanded into a range of other industries, including intelligent connected new-energy vehicles, optoelectronic information, hydrogen energy, intelligent robotics, the low-altitude economy and green building materials.

　　"The spirit of craftsmanship, fueled by a drive to grow stronger and tempered through countless trials, continues to inspire us to create new wonders," Pan noted.

　　(Web editor: Zhang Kaiwei, Liang Jun)