Underground coal mining
As opposed to opencast mines, in underground mines, the layers covering coal are not removed; coal is extracted through mine shafts.
3 – 12-р анги
Түлхүүр үгс
mozaLink
/Веб холбоос
As opposed to opencast mines, in underground mines, the layers covering coal are not removed; coal is extracted through mine shafts.
3 – 12-р анги
Түлхүүр үгс
mozaLink
/Веб холбоос