'The most difficult job of my life'

For Rudi Wolf, the past month has been the most challenging and tiring he has ever had to endure. It has also been one of the most rewarding.

The 55-year-old was a technical consultant for the rescue team that worked for 36 days to return four trapped miners to the surface on Friday night.

"The job here has been the most difficult of my life," said the German drilling expert, who was called in to help shortly after the gypsum mine collapse in Pingyi county, Shandong province, on Dec 25.