Abstract: The open-pit mining safety was threatened by the large amount of mined-out area under Sandaozhuan Open Pit Mine, Luoyang Molybdenum Group.The mined-out areas were classified and analyzed and different treatment processes were used for them respectively.For example, long and medium hole explosion and long hole explosion were used for different areas for 145 times, which involved a mined-out area of 116.3hm² and a volume of 13.392 million  m³.This technical method has effectively solved the problems in mining safety and explored a new effective way for the treatment of mined-out area, making the work into an orderly, normalized and scientific stage.It is of important reference significance to the safe and rational development of domestic mine resources of the same type.

Key words: Open mined-out area, Treatment process, Technical exploration