Sublevel open stopping is a vertical mining method where a large open stope is created within an ore vein. Three variations are used: blast hole, open ending, and vertical crater retreat. Drilling is done from multiple sublevels using fan or parallel patterns. Ore is mucked using load haul dump equipment or slushers and transported to surface via skips or haul trucks. Pillars are left in place for support and ground conditioning uses bolts. Backfill allows for recovery of up to 90% of ore while providing support. It is suitable for moderate to strong ore bodies that are fairly steep, thick, and tabular in shape. Advantages include moderate productivity while disadvantages include complex development and inflexible planning.

1. Sublevel open stopping
Virendra suryawanshi
10108EN066

2. Sublevel open stopping
sublevel stoping is a vertical mining method in which a
large open stope is create within the vein. This open stope
is not meant to be occupied by the miners therefore ,all
work of drilling and must be performed from sublevel
within the ore block.
Three different variations of sublevel stoping are practiced
1. Blast hole method .
2. Open ending method.
3. Vertical Crater Retreat (VCR) method.

4. Development
1.Stope sequence
2.Drilling
3.Blasting

5. Fan Drill Pattern from multiple drift levels
Parallel Drill Pattern in a Sublevel
Stope

6. Labelled Stope Layout with Ring
Drilling

7. Equipment
Sublevel open stopping is a highly mechanized mining method utilizing a wide
range of equipment for drilling and mucking. Typically production drilling is
carried out by high-efficiency column and arm long hole drills or DTH drill rigs.
These systems use electric drive instead of hydraulic and have high pressure
pneumatic DTH hammers or rotary percussion drilling systems. It is with
recent advantages in drilling technology that these systems have
revolutionized sublevel stopping operations.
Mucking may be done with load haul dump equipment or LHD’s. They either
take the ore from the draw point entrances and travel to an ore skip location
for shaft transportation of ore to surface, or they transport and load the ore
onto haul trucks which then transport the ore to surface via ramp access.
Slusher and scraper systems have also been used in combination with mine
car transport as well. In this scenario, the ore is scraped into designated ore
passes where it falls into waiting mine cars. These cars then either transport
the ore to waiting haul trucks or to skip locations as described previously.

8. Support
1.Pillars
A wide array of pillars are used in a typical sublevel stopping
operation. Rib pillars are installed as a support divider between
horizontally adjacent stopes. During production, as vertical slices
are blasted away, some slices are left behind as support pillars in
order to help control subsidence within the stope. Sill and crown
pillars are also a key support development in sublevel stoping.
They are used between vertically adjacent stopes (sill pillar) or
between a stope and surface operations (crown pillar). These
pillars provide roof and floor support as well as aid in the
prevention of cave-ins, rock bursting, and surface subsidence

9. Backfill
In sublevel stoping a backfill program is usually established in
large openings created during production. Backfill allows for the
recovery of support pillars, permitting up to 90% ore recovery.
Apart from this, backfill provides additional ground support,
reduces dilution and helps with the redistribution of stresses
around openings, which reduces rock bursting events.
Ground Support
Due to the strong nature of the rock required for use of this
method, ground support is usually minimal. However ground
conditioning is still needed in some areas and is done using different
types of bolts including cable/rock bolts and grouted rebar. In Canada,
any opening in which workers will be present needs to have a minimum
bolt pattern before the workers are allowed to work freely.

10. Applicability condition
1.Ore strength: moderate to strong, may be less competent than
for stope and pillar mining.
2.Rock strength: Fairly strong to strong.
3.Deposit dip: Fairly steep (>45 degree , preferably 60 to 90
degree ).
4.Deposite size: Moderate to thick width (20 to 100 ft or 6 to
30m), fairly large extent.
5.Deposite shape: Tabular or lenticular, regular dip and
boundaries helpful.

11. Advantage
1.Moderate to high productivity.
2.Moderate to high production rate.
3.Low breakage cost; fairly low handling cost.
4.Fair recovery (about 75%).
5.Modest dilution (about 20%)

12. Disadvantage
1.Fairly complicated and expensive
development.
2.Inflexible in mining plan.
3.Long hole drilling requires precision
(<2%deviation).
4.Large blasts can cause significant vibration ,
air blast , and structural damage

13. Thank you