Sunny disposition

In addition to reducing the number of workers, the systems have shortened the time miners have to remain underground.

Meng, from the Gaozhuang Mine, said that he is now always in a good mood, as he has time to enjoy the sunshine.

"Years ago, I went to work underground early in the morning before sunrise, returning home after sunset. I seldom saw daylight," he said.

"With a tough working schedule and little sunshine, I felt life was so boring and exhausting. I didn't have time to take care of my family, and my wife regretted marrying a miner."

In 2017, the Gaozhuang Mine began to install automated facilities. Before the machinery was introduced, Meng and his colleagues had to carry heavy picks and dig coal from tunnel walls. Now, they operate automated drilling machines.

Miners also used to carry large sacks of coal waste on their backs, but now machines place the waste on conveyer belts, which carry it to the surface.

"We just click a button to start all the operations, including tunneling, cutting coal and transportation," Meng said.

He added that 30 workers used to be required at the coalface for one shift, but now only seven are needed.

The machinery also means that employees such as Meng work just six hours a day. "I get to spend every weekend playing with my two children. It's impossible not to remain in a good mood," he said.

In 2017, the Fucun Mine in Jining, Shandong, which is also owned by the Zaozhuang Mine Group, became the first in China to cancel underground night shifts.

No workers are sent into the shafts after midnight, the time previously when a new shift began.

Tunneling, power supply, transportation, water drainage and ventilation at the mine are all remotely controlled from the surface.

The colliery's deputy manager, Wang Shikui, said miners who are no longer required to work underground are now employed at plants built to maintain the new facilities.