Room and Pillar Stope Splitting

The Stope Splitting tools in MSO post-processing allows you to subdivide larger stopes into smaller units for more practical scheduling and operational implementation.

Room and Pillar is a mining method where extraction is divided into alternating mined openings (rooms) and unmined support material (pillars). In MSO, Room and Pillar stope splitting applies this concept during post-processing by subdividing slice-generated stopes into a regular pattern of rooms separated by pillars.

This option is available only for the Horizontal Slice framework, where stopes are naturally defined in vertical stacks and can be systematically segmented.

You choose this type of splitting using the Post Processing screen's Room and Pillar Splitting Type.

You would use Room and Pillar splitting when:

Designing stopes intended for room-and-pillar style extraction.
Requiring regular, repeatable stope layouts.
Needing to preserve in situ support material for stability.
Aligning optimisation results with conventional underground mining practices.

Some important notes about this type of stope splitting:

Room and Pillar splitting is intended for post-processing only and does not influence optimisation decisions.
Cut Height and RL Origin should be chosen to align with mine design levels or planned extraction horizons.
Minimum Ore and Minimum Waste thresholds should reflect geotechnical and operational requirements, not just grade.
A visual review of split stopes is recommended to confirm practical layouts.

How Room and Pillar Splitting Works

Room and Pillar splitting works by:

Starting from the specified RL Origin.
Applying horizontal cuts at intervals defined by Cut Height.
Evaluating each resulting section based on its ore and waste content.
Retaining sections that meet Minimum Ore criteria as rooms.
Retaining sections that meet Minimum Waste criteria as pillars.

This process produces a regular, structured layout that balances ore recovery with in situ support.

Reference Level Origin

How you determine your reference level (RL) origin can be subjective. RL Origin defines the vertical reference level from which Room and Pillar cut heights are measured. Its purpose is to ensure that horizontal splits align consistently with mine design levels, rather than being tied arbitrarily to the stope geometry.

Most commonly the level is decided in relation to the mine design, matching a known mine level, such as:

A planned extraction level.
A development horizon.
A survey reference level.

This ensures that:

Room and pillar cuts align with actual mining horizons.
Pillars and rooms repeat consistently across stopes.
Results are predictable and easy to validate.

This is the preferred option for production-oriented designs.

Other scenarios include choosing a consistent geological or structural horizon (say, a stratigraphic boundary) or even the lowest elevation of the block model, although commonly, mine levels wouldn't exist there, meaning paths may not align with planned mining levels.

The key requirement is that the RL Origin:

Is stable and repeatable.
Is meaningful within the mine’s vertical reference system.
Aligns with how vertical spacing is defined elsewhere in the design.

Small changes to the RL Origin can shift all cuts, so it should be chosen deliberately rather than automatically.

Define Stope Splitting Options

To define post-processing settings for stope splitting in a Room and Pillar scenario:

Ensure your Orientation screen's Optimization Method is Slice and the Geometry is Horizontal.

Note: Room and Pillar stope splitting is only available with horizontal slice frameworks.
Display the Post Processing screen.
Check Use Stope Splitting.
Select Room and Pillar from the Splitting Type list.
Specify a Cut Height. This defines the vertical height of each split section which, in turn, controls the spacing of horizontal cuts used to divide the stope into rooms and pillars.

Note: This setting is typically aligned with mining lift or equipment constraints.
Define Minimum Ore. This specifies the minimum amount of ore material required within a split section for it to be retained as a room. Sections with less ore than this threshold may be discarded or treated as pillars.
Define Minimum Waste. This specifies the minimum amount of waste material required within a split section for it to be considered a pillar. This helps ensure that retained pillars contain sufficient non-ore material to provide support.

Note: These thresholds are applied during post-processing and do not affect optimisation or grade cutoffs.

Important: Both Minimum Ore and Minimum Waste represent absolute amounts of material (typically tonnes or volume, depending on the MSO configuration), evaluated within each split section created by Room and Pillar splitting. The units used are the same units MSO uses internally for material reporting, typically. These are not cutoff, grade or percentage values.
Specify the RL Origin. This defines the reference level (RL) from which cut heights are measured. All vertical splitting is aligned relative to this origin to ensure consistent and repeatable room and pillar placement.

See Reference Level Origin.
Save your post processing settings.