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Underground coal mining
As opposed to opencast mines, in underground mines, the layers covering coal are not removed; coal is extracted through mine shafts.
Grades 3 – 12
کلیدواژهها
موزالينک
/لينک وب
As opposed to opencast mines, in underground mines, the layers covering coal are not removed; coal is extracted through mine shafts.
Grades 3 – 12
کلیدواژهها
موزالينک
/لينک وب