09-04-2012, 02:12 PM
Underground Mining Methods
Underground Mining Method ppt.pptx (Size: 2.09 MB / Downloads: 75)
Longwall mining method
Complete removal of the entire seam in one operation .
Leaving no pillars and allowing the roof to cave behind the face.
Provides continuous production and full potential for automation.
Blasting gallery method
Induced caving by blasting during depillaring of panels in underground mines
BG method is a semi mechanized caving method, which involves retreating along level galleries, while extracting the maximum possible thickness of the seam
BG method involves splitting along the level of developed pillars in the bottom section into two rectangular stooks and adequately supporting the widened galleries by hydraulic props and roof bars at least two pillars ahead of the pillar under extraction.
Advantages of blasting gallery method:
Less capital intensive as compared to longwall
Less skilled manpower needed compare to longwall
Higher production (400-500 t/day/panel) and productivity
Extraction of hard coal not suitable for ploughs and shearer
Extraction of small size panels not suitable for longwall method
In case of BG failure, equipments can be used for heading drivages
The workers/operators are always under the supported roof
Applications:
Ore bodies with horizontal or flat dip, inclination not exceeding 30⁰.
Competent rock in the hanging wall and ore.
Sublevel caving method:
Sublevel caving is a mass mining method based upon gravity flow of blasted ore and caved waste rock.
Its major advantage is safety.
There is relatively high dilution of ore by caved waste.
Some ore is lost in passive zones between those of active flow.