TS. Product Specifications
- iarmstrong
- 1 Overview
- 2 Cash Flows
- 3 Blend Target
- 4 Grade Targets
- 4.1 Grade Fields
- 4.1.1 Insitu Fields
- 4.1.2 Process Streams Fields
- 4.1.3 Output Fields
- 4.2 Grade Lower Limit
- 4.3 Grade Upper Limit
- 4.4 Grade Target
- 4.5 Content Deviation Penalties
- 4.1 Grade Fields
Overview
This step is only visible when scheduling in the Optimise Products mode and hidden if it’s set to Constrain to Truck in the Configuration Options step.
When the user presses the button to run one period in the Schedule, there are two passes happening behind the scenes.
The Product Specifications step allows the user to define the rules of the optimisation. Each rule becomes a new row in the Calendar. Values for the rule are specified in Schedule > Calendar > Product Specifications.
Adding Product Specification
To add the optimisation rule, press the Add Product Specification button and select a type from the dropdown.
2. Name the rule clearly. Avoid using commas in the Product Specification rule name, otherwise you will get an error message preventing you from going past this step:
<The name of product specification (…), is invalid because it contains invalid characters>.
3. Toggle the Use Spec flag to enable or disable usage of the Product Specification rule.
4. Click the field in the Configuration column to customise the optimisation rule. Once completed, the configuration field will list all of the populated fields.
Product Specification types
Product Specifications 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.
Product Specification type | Usage |
|---|---|
Cash Flow | Reward (or penalty) to send material to a destination. |
Blend Target | Penalty for failing to meet blend ratios. |
Grade Target | Penalty for failing for meet grade specs. |
Detailed description of each Product Specification type and their impact on the optimisation process see below.
Cash Flows
Cash Flows allow the user to specify an incremental Reward or Penalty for each tonne/cubic meter/ounce of material sent to a Destination.
Cash Flows help the user to have better control over the fleet allocation, prioritising more profitable movements.
If two rules satisfy the same condition, then the cash flow is the sum of values in each rule.
The chart above shows an example of the cash flow allocation for prioritising different ex-pit ore movements, namely:
The reward for direct ore movement from the Pit to the Crusher is $100, which makes this transaction the most profitable and therefore prioritised by the optimiser.
The reward for feeding a unit of high-grade ore from the Pit to the HG stockpile is $20, and medium-grade ore to the MG stockpile is $10, which prioritises moving of the high-grade over medium-grade material.
Similarly with the reclaiming of HG and MG stockpiles: since the reward for feeding the Crusher with high-grade material is higher than that for feeding the medium-grade, the HG stockpile will be given greater preference to reclaim.
Finally, the mineralised waste movement is the least profitable in comparison to ore flows, but may still be applicable in some periods, such as when high and medium grade ore is not available. If a negative cash flow is placed on this movement, feeding mineralized waste to the Crusher will be penalized because, for example, it may cost more in resource usage (machinery hours, fuel consumption, etc.) than will be received after processing a unit of this type of material.
Stockpiles and Crushers Cash Flows
Cash Flow rules for Stockpiles and Crushers 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.
Set the Source(s), Material(s), Destination(s), and unit (Quantity Field) on which to apply the Cash Flow.
Cash Flows by Plant
The example below allows the user to control the priority of the Wet plant and Dry plant, and prefer certain materials into each plant.
$30 reward per railed tonne from the Dry plant.
$30 reward per railed tonne from the Wet plant.
$10 reward per railed tonne of HG from the Dry plant.
$10 reward per railed tonne of LG from the Wet plant.
The sum across these values means that HG returns ($40) from the Dry plant and ($30) from the Wet plant, whereas LG returns ($30) from the Dry plant and ($40) from the Wet plant. As such, the optimiser prefers to sent HG to the Dry plant but can top up the Wet plant if required.
Cash Flows by Material
This example prioritises feeding HG first, then MG, then LG, to maximise the returned metal content.
$100 reward per feed tonne of HG.
$50 reward per feed tonne of MG.
$20 reward per feed tonne of LG.
Cash Flow Values
Cash flow values are strictly relative. Setting all fields to "10" is the same as setting all fields to "10000".
Users are encouraged to pick values that express the relative importance of each transaction. For example, if high grade yields twice the revenue of low grade, give it twice the cash flow.
Cash Flows between Stockpiles
To enable movement between stockpiles:
Press Add Product Specification button and from its dropdown select "Stockpile Cash Flow".
Name it as "RehandleThreshold_setTo1000", for example.
Set the units to “mining_” volume or Tonnes, depending on the units you schedule the material in these stockpiles.
Select the Source and Destination stockpile.
In the Calendar, set the cash flow to 1001.
Blend Target
Item | Description | Example |
|---|---|---|
Specify Min | Limits minimum ratio of the material fed from the Source to the Destination.
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Specify Max | Limits maximum ratio of the material fed from the Source to the Destination.
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Specify Target | Specifying target also introduces “Content Deviation Penalty” input row in the Calendar. The difference between the Actual and the Target blend is subject to this Penalty multiplier specified by the user. The Penalty is summed with the Cash Flows to determine the reward or cost of blending materials into each Destination. The higher the deviation penalty, the better the optimizer will try to meet the target, but it may not be achieved due to other cash flows and objectives. | |
Show Tram Lines | Displaying additional guidance rows for the optimisation rule in the Calendar. Used for visual purposes only to change the color of values in the “Actuals” field, i.e. if it goes out of range by more than 0.0001 it goes red, less than orange, otherwise it's black. | |
Numerator and Denominator | Blend ratios are calculated using a Numerator and Denominator, as such the setup requires both to be populated. | |
Destinations | The Destination(s) to which the blend target is applied. | |
Quantity Field | The field to which the blend target is applied. | |
Sources | The Source(s) for Numerator and Denominator to which the blend target is applied. |
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View Database | Use the View Database button to open the Choose Records window, where you can graphically select and review the Sources. | |
Example: blend X up to 10%
This example targets a 10% LG blend into the crusher, but still feeds if there is no LG available.
$100 reward per feed tonne of LG.
10% maximum ratio of LG into crusher feed.
Grade Targets
Grade Fields
Grade specifications can be set to reference any field in the database.
Type | Example Field | Application | Note |
|---|---|---|---|
Insitu Fields | mining_grades_fe | Insitu Grade/Head Grade | Use these fields on Stockpiles and Crushers when targeting a head grade. |
Process Streams Fields | mining_ProcessStreams_dry_rail_SubProducts_fines_grades_fe | Fines product grade, through the "dry" plant, at the "rail" point | Use these fields to target product grades on Stockpiles. Since the software does not know what Crusher the Stockpile will feed into, the user is required to specify the Processing Stream of the quantity fields. To configure the dry/wet, rail/ship, lump/fine process stream options, see Setup > Processing Paths. |
mining_ProcessStreams_dry_rail_grades_fe | Total (Lump + Fines) product grade, through the "dry" plant, at the "rail" point | ||
Output Fields | Output>rail_SubProducts_fines_grades_fe | Fines product grade, through the (wildcard) plant, at the "rail" point | Use these fields to target product grades through Crushers. Since the software knows the Processing Stream for each Crusher, the “Output” fields act as a wildcard to automatically select the corresponding grade fields. |
Grade Limits and Targets are explained in the table below.
Input | Description | Notes |
|---|---|---|
Grade Lower Limit | The final weighted average grade cannot be below this value.
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Grade Upper Limit | The final weighted average grade cannot be above this value.
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Grade Target | The difference between the Actual grade and the Target grade is subject to a penalty multiplier specified by the user.
If Crusher A and Crusher B have different grade targets, then a single block will incur a different penalty depending on the destination. This penalty is summed with the Cash Flows to determine the reward or cost of blending materials into each destination. | |
Content Deviation Penalties | The value of the content deviation penalty should be considered relative to other grades, and relative to the Cash Flow values.
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