Half coal rock lane quick-excavating technique under the condition of "two hard" has always been a main excavating problem influencing the Datong mining Cop.
前言：“两硬”条件下半煤岩巷掘进一直是影响大同煤矿集团有限责任公司采掘关系的主要问题。
2
The damage styles of cast-in cutting pick and hard-solder forging cutting pick are analyzedaccording to the comparing experiment under coalmining well.
通过井下采煤对比试验，分析了镶铸截齿与锻造针焊截齿的损坏特点。
3
Xinli mining area of Sanshandao gold deposit is the first hard rock mine which belongs to the under-sea deposit in our country, and only Longkou is miningcoal under sea in domestic.