A total of 40 people were working underground at the mine in Yining county, about 100km from the border with Kazakhstan, at the time of the collapse Saturday afternoon.
Twenty-two miners were brought to the surface but 18 remain trapped.
“A rescue operation is underway to retrieve the remaining miners,” Xinhua news agency said late Saturday.
Mine safety has improved in recent decades, as has media coverage of major incidents, many of which were once overlooked.
But accidents still occur frequently in an industry where safety instructions are often lax, especially at the most rudimentary sites.
In September last year, 19 miners stranded underground after the collapse of a coal mine in the northwest province of Qinghai were found dead after a long search.
But in December 2021, 20 miners were rescued from a flooded coal mine in northern Shanxi province while two others died.