Board & Pillar

Step mining
 It is an adaptation for the case
where the dip of the ore body is
too big (15o to 30o) to use
equipment on tires at the same
time that its thickness is
relatively small (2 - 5 m). A
special orientation of transit
and stops galleries creates areas
with horizontal floor, allowing
the use of equipment on tires.
The mining progresses from top
to bottom in mining panels.

Post-pillar mining
 Applies to inclined
deposits with dip
between 20o and 55o.
Have large vertical
dimension, and filling the
mined space suffers
(backfilling). The filler
maintains the stable rock
(minimizes columns) and
serves as a working
platform for the next
slice.

Regularly spaced openings formed orthogonal
arrangement of square or rectangular pillars.
Development (axle) and exploitation (panel)
galleries usually have very similar characteristics.
several parallel galleries and connected by
dashes.
is a method for mining large-scale, with the
various panels can be conducted simultaneously.
the basic unit of mining is the panel that defines
the area to be worked and ventilated.

a) Dimensions of the Galleries
b) Dimensions of the Pillars
c) Mining with or without Recovery of
Pillars
d) Number of Front Panel

 Widths of 5 to 6m are currently quite common.
 Height is limited by the thickness of mineable coal (in SC
deposits, the section is rectangular with heights ranging
from 2.0m to 3.5m approx.).
 Condition shoring ceiling.
 Interfere in operational and safety aspects.
 Dimensions are used to calculate the recovery of mining.

 Currently, for the Boards and Pillars method to succeed, the
deposits must have a particular geological condition of the roof. The
overlying layer extracts the coal must be self-sustaining condition or
be likely anchor (there are several types of anchoring screws ceiling,
with different principles of operation - see Appendix A).
 Due to costs, shoring bows with metal or wood are used only in
restricted areas of the mine.

influence on operational aspects (e.g.
transport distances) and safety (risk of
collapse of pillars).
influence the recovery of mining.
Types of pillars.
o square and rectangular pillars
o chain pillars (internal pillars of the mining panel)
o barrier pillars (the pillars of safety)

most common ways of mining ...
Recovery strategies pillars .

Equipment to aid in the recovery of
pillars.

The advancement of the panel is done through
several parallel galleries (5 galleries or more,
depending on the mine) connected by dashes. It
takes more fronts in conventional mode (drill-
blast-load-haul) and less fronts with continuous
miner. The use of continuous miner least affects
the roof and pillars and produces thin material.

 Moderate to high productivity (m3 / man-hour)
 Moderate cost of mining (relative cost = 0.3)
 Moderate to high production rate
 High degree of flexibility (allows variable thickness in
the ore); method easily modifiable; may operate
simultaneously on multiple levels
 Allows high degree of mechanization
 Selective method, lets leave waste material on site.
 Does not require much anticipated development.
 It can be operated on multiple fronts.

 Reasonable recovery without extraction of pillars (50-
65% on carbon), low dilution (10-20%).
 Comparing with Longwall. LW is Pratic. inflexible,
requires greater investment, there is subsidence on the
surface, has high yields (must be a market for the
product!), LW global recoveries are possibly lower than
B & P with pillar recovery.
 In direct comparison with Longwall. LW is Pratic.
inflexible, requires greater investment, there is
subsidence on the surface, has high yields (must be a
market for the product!), LW global recoveries are
often lower than B & P with pillar recovery.

Requires ongoing maintenance of the roof and
eventually the pillars. The tension in the open
spaces increases with depth.
Significant capital investment for extensive
mechanization.
Loss of ore in pillars.
In the case of B & P in hard rock, it may be
difficult to achieve good ventilation to dilute
contaminants in due to low air velocity panel in
large open spaces.
Requires good technical and engineering support.

Board & Pillar

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Board & Pillar