PS. Flow Optimisation

Optimisation rules set in the Flow Optimisation step tell the software user’s display preferences (grades, blends, tonnes) when calculating destinations and product handling.

1 Overview
2 Rule Types
- 2.1 Cash Flows
- 2.2 Max Rate
- 2.3 Grade Targets
- 2.4 Blend Targets
- 2.5 Max Quantity

Flow Optimization step overview

Overview

Flow rules are used to determine the best destination for material at each time step. The best destination is defined as the one yielding the highest positive cash flow, where the cash flow is the sum of all rewards and penalties.

Rule Type	Usage

Rule Type	Usage
Cash Flow	Reward (or penalty) to send material to a destination
Max Rate	Limit build rates at stockpiles and dumps
Grade Target	Penalty for failing for meet grade specs
Blend Target	Penalty for failing to meet blend ratios
Max Quantity	Limit total quantity sent between a set of sources and destinations

Rule Calculation Type	Behavior

Rule Calculation Type	Behavior
Instantaneous	Target is evaluated for every instant in time
Stockpile	Target is evaluated over the complete build of target stockpile
Period	Target is evaluated over the entire period duration

Typically a destination will be assigned at least one positive cash flow (reward for sending material), as well as several grade targets (penalties for going off-spec). The optimiser then sieves out a selection of blocks that (if possible) yield high rewards and low penalties.

Destinations with a net negative cash flows are discarded. For example, the crusher may decide not to feed material if the grade penalty outweighs the reward for movement.

Rule Types

Cash Flows

Cash flow rules define a dollars-per-unit rate on material types conveyed between sources and destinations. Once a rule is configured, the rate is specified in the calendar.

Crusher cash flow

Configuration Item	Description

Configuration Item	Description
Input Method	Separately: creates a discrete cash flow for each checked arrow Combined: creates a single cash flow that applies to all checked arrows
Arrows	The destination(s) to which the cash flow is applied
Fields	Separate cash flows are added for each checked field
Sources	Filter the sources to which the cash flow is applied
Parcels	Filter the parcels to which the cash flow is applied
Agents	Filter the agents to which the cash flow is applied

Max Rate

Max Rate limits the optimiser to a specific rate for an instant in time.

Configuration Item	Description

Configuration Item	Description
Input Method	Separately: creates a discrete max rate for each checked arrow Combined: creates a single max rate that targets an average grade across all checked arrows
Arrows	The destination(s) to which the max rate is applied
Fields	The field to which the max rate is applied
Sources	Filter the sources to which the max rate is applied
Parcels	Filter the parcels to which the max rate is applied
Agents	Filter the agents to which the max rate is applied

Grade Targets

Grade targets penalise the optimiser for going off-spec. The optimiser balances between positive cash flows and negative grade penalties to match blocks to destinations.

Configuration Item	Description

Configuration Item	Description
Input Method	Separately: creates a discrete grade target for each checked arrow Combined: creates a single grade target that targets an average grade across all checked arrows
Arrows	The destination(s) to which the grade target is applied
Fields	Separate grade targets are added for each checked field
Sources	Filter the sources to which the grade target is applied
Parcels	Filter the parcels to which the grade target is applied

Blend Targets

Blend targets penalise the optimiser for going off-blend. The optimiser balances between positive cash flows and negative blend penalties to match blocks to destinations.

Configuration Item	Description

Configuration Item	Description
Numerator and Denominator	Blend ratios are calculated using a Numerator and Denominator, as such the setup requires both to be populated
Arrows	The destination(s) to which the blend target is applied
Quantity Field	The field to which the blend target is applied
Parcels	The parcel(s) to which the blend target is applied
Sources	The source(s) to which the blend target is applied

Max Quantity

Max Quantity limits the optimiser to a specific quantity over a period of time.

Configuration Item	Description

Configuration Item	Description
Input Method	Separately: creates a discrete max quantity for each checked arrow Combined: creates a single max rate that targets an average grade across all checked arrows
Arrows	The destination(s) to which the max quantity is applied
Fields	The field to which the max quantity is applied
Sources	Filter the sources to which the max quantity is applied
Parcels	Filter the parcels to which the max quantity is applied
Agents	Filter the agents to which the max quantity is applied