Open Pit Mine Scheduling Workflows

FAQ

What are Bench Solids and how are they used?

Bench solids are formed from the intersection of the nested pits and the benches. They allow you to schedule using nested pit increments on benches instead of mining blocks - essentially a simple form of automated pushback scheduling. Since you will typically end up with significantly fewer bench solids than mining blocks, it's quicker to build the schedule with them - provided that they give you the granularity that you require.

What are Mining Blocks and how are they used?

You will probably use mining blocks extensively - both with pit optimisations and Direct Block Scheduling (DBS). Mining blocks divide the shells (either block model outer or pit stages) into a 3D grid of blocks that can then have dependencies applied and be scheduled individually. As you'll see from the workflow summaries, there isn’t much difference between scheduling from pit optimisations and DBS - it all comes down to how you define your boundaries. Effectively, the mining blocks reblock the block model within the confines of the specified shells. If you have a pit optimisation and you're happy that the inherent NPV objective is not going to constrain the schedule adversely, use the nested pit shells. If not, use DBS, create mining blocks as required from the block model outer shell and schedule those.

Which solids from the Pit Optimiser do I need for Scheduling?

If you require Scheduling only to work within the constraints of the final pit shell, specify the appropriate Stage Solid. If you require Scheduling to understand and sequence within the structure of the nested pits, specify the ordered list of corresponding Incremental Solids. The Pit Optimiser includes output options for both. Use Incremental Solids if you want to force the stages into Scheduling. Use the final Stage Solid if you want Scheduling to work them out.

Single Open-Pit Mine Scheduling Workflows

  • Resource model(s)

  • Multiple alternative workflows

    • Multiple resource models supported for each

  • Final object (solid) in each workflow becomes task in schedule

  • Dependencies between tasks to support each workflow

    • Slope angles, bench solids, or simple 1:1 step

Multiple Alternative Open-Pit Workflows

#

Open-Pit Workflow Option

Summary

1

Resource model -> Mining Blocks (#1 Direct Block Scheduling)

  • Outer shell of block model delineates optimisation region
  • Cut outer shell of block model into 3D grid of mining blocks

  • Calculate attributes for mining blocks by aggregating blocks and parts thereof from block model

    • Effectively reblocking with custom fields and aggregation rules

    • Block aggregation reduces size of optimisation problem

  • Use grid indexes to determine task (mining block) dependencies

  • Optimiser extracts mining blocks to limit of outer shell to satisfy objective, subject to slope angle dependencies and production constraints

  • Derives optimum pit and schedule simultaneously for each period

2

#2 Pit Optimisation -> Mining Blocks

  • Run pit optimisation

  • Cut selected pit shell into 3D grid of mining blocks

  • Calculate attributes from block model

  • Use grid indexes to determine task (mining block) dependencies

* Equivalent to #1: Direct Block Scheduling using pit shell instead of outer shell of block model

3

#3 Pit Optimisation -> Nested Pits -> Mining Blocks

  • Run pit optimisation

  • Cut selected incremental pit shells into 3D grid of mining blocks split by shell boundaries.

  • Calculate attributes from block model.

  • Use grid indexes to determine task (mining block) dependencies.

* Similar to #2: Pit Optimisation -> Mining Blocks using multiple stage shells instead of only final pit shell

4

#4 Pit Optimisation -> Nested Pits -> Bench Solids
(Manual process)

Pit Optimisation -> Bench Solids
(Integrated into Schedule Definition)

  • Run pit optimisation.

  • Create bench solids from intersection of each nested pit increment with each bench.

    • Apply optional minimum mining width.

  • Calculate attributes from block model.

  • Use extraction numbers and bench heights to determine task (bench solid) dependencies.

5

#5 Pit Optimisation -> Nested Pits -> Pit Designs -> Incremental Solids -> Mining Blocks

  • Run pit optimisation.

  • Create pit designs for selected nested pit shells.

  • Create incremental solids for pit designs.

  • Cut incremental solids into 3D grid of mining blocks split by pit design boundaries.

  • Calculate attributes from block model.

  • Use grid indexes to determine task (mining block) dependencies.

6

#6 Direct Block Scheduling -> EOP Surfaces -> Pit Designs -> Incremental Solids -> Mining Blocks

  • Run #1: Direct Block Schedule.

  • Create cumulative solids for selected end-of-period (EOP) pit shells.

  • Create pit designs for EOP cumulative solids.

  • Create incremental solids for pit designs.

  • Cut incremental solids into 3D grid of mining blocks split by pit design boundaries.

  • Calculate attributes from block model.

  • Use grid indexes to determine task (mining block) dependencies.

Summary of Alternative OP Workflows (1)

FROM …

Pit Optimisation

Direct Block Scheduling

Pit Optimisation

Resource Model Outer Shell

(Direct Block Schedule)

End-of-Period Surfaces

Pit Shells (Stage Solids)

Pit Designs

Incremental (Stage Solids) with Extraction Numbers

 

Summary of Alternative OP Workflows (2)

WITH …

Mining Blocks

Bench Solids

Create Mining Blocks
(with optional splits at stage shell boundaries)

Create Bench Solids
(with optional minimum mining width)

Attribute Solids from Resource Model
(aggregates blocks and parts thereof as required)

Dependencies for Mining Blocks

Dependencies for Bench Solids

Optimisation

Animation

Reports and Charts