METHOD OF WORK:
According to method of mining,coal mines are of two types.Open cast mine and Underground mines. Open cast mine:- In opencast method,soil and rock lying over small area of the coal seam is blasted,excavated and dumped on no coal bearing surface nearby.The exposed coal is blasted and mined. Operation of removal of overburden and extraction of coal continue.After coal has been removed over a large area,the over burden is dumped in the trench formed by removal of coal.This is called "backfilling". O verburden is excavated in steps called benches for reasons of saftey and ease of extraction.Coal seam is also extracted in more than one bench if it is thick.Bench are approached by wide road ways called haul roads, because they are used for transporting or hauling of overburden or coal. Underground mine:- Where the coa...