Global Targets

To access this screen:

On the Scheduling Setup screen, select Constraints >> Targets >> Advanced.

Use the Targets panel to define and view global mass targets for your schedule in your application.

An advanced target (also known as a global target) is either a ratio or a rate.

Like a standard target, an advanced mass target is defined by an expression that combines mass variables and other elements.

Mass variables can be defined using an element from any destination.

Advanced Target Mass Variables

A Mass variable comprises the following information components:

Category

A material category can be either of the following:

A category within the current reserves table, or;
A define stockpile. Stockpiles are available here as they can be regarded as a category because they are supplying material onwards to the plant.

Destination

Any valid destination can be selected, once a category has been defined. Only destinations that have been constrained to receive the nominated material category will be available.
Element

What variable is being measured? All numeric fields in the reserves table are listed here. For example, if you were setting up a rate-based mass variable to maximize tonnage over a time period, you would select TONNES. Any non-system numeric attribute can be an element.
Numerator

For a rate-type target, this represents the factor to be applied to the element. For example if a Numerator of 1.15 is applied to VOLUME being sent to the leach pad (say, to account for wastage in transit), the resulting expression would be:
```
[HIGH,Leach,VOLUME] * 1.15
```
For a ratio type target, the Numerator is part of the Numerator/Denominator pair used to describe a proportion of an Element, say, 95% of TONNES
Denominator

Note: Available only if a Ratio target type is being defined.

Mass variable configuration must be unique for a given target; you won't be able to define the same mass variable combination twice for the same target.

Advanced Target Example

For example, you might limit the total tonnage of high-grade and medium-grade stockpile material going to the plant to between 16,000 and 20,000 tonnes for period 3.

As this constraint involves two destinations (plant and stockpile), an advanced mass target is relevant.

In this case, two mass variables are defined to construct an expression.

[HG Stockpile,Plant,TONNES] + [MG Stockpile,Plant,TONNES].

Breaking this down, the mass variables defined for the expression are:

HG Stockpile, Plant, TONNES.

Defined as:
- Category: HG Stockpile (destination).
- Destination: Plant (destination).
- Element: TONNES.
- Numerator: 1.
- Denominator: 0 (this is a rate target).
MG Stockpile, Plant, TONNES.

Defined as:
- Category: MG Stockpile (destination).
- Destination: Plant (destination).
- Element: TONNES.
- Numerator: 1.
- Denominator: 0.

Selecting the global mass target in the table opens the Target Bounds table so you can define a Minimum (16,000) and Maximum (20,000) limit for time period 3.

The Use tick box is enabled to ensure the target is active during scheduling.

Standard & Advanced Targets

Similar to standard grade/quality targets for destinations, advanced targets can create targets across multiple destinations including ratios, for example, total pit excavation vs. reclaim amounts. Within advanced targets grade values are considered as metal tonnages so to achieve the same target as a standard destination grade target within global it must be a ratio where the grade is divided by the weighted field. For example:

Standard Target AU,
Advanced Target AU/Tonnes

...will both give the same result.

Targets are output to the Targets control bar for both global and destinations where the values in the schedule are calculated for the period(s).

Global Mass Targets – Golden Rules

Important rules for setting targets:

Only one global mass target can be set in the Obj. Function drop-down list as [Minimize] or [Maximize].
All other targets must be set to a [Bounds] objective.
If the target is set to be a ratio type, it cannot be an objective function.
If the target is an objective function, it cannot later be altered to a ratio target type.

Defining Target Bounds

All target bounds are defined as mass.

Mass variables represent the mass, not grade, of an element.

If an element is not defined, the variable represents the mass of the category to the selected destination.

The associated minimum and maximum target values are therefore also in mass units.

For each target, define one or more records for End Period, Minimum and Maximum values for the current target.

Your application searches for schedules that keep all target variables within the specified bounds.

You can vary the bounds over time.

Row	End Time	Minimum	Maximum
1	2	2	6
2	10	0	4
3	200	0	5

To add a global mass target variable, details and bounds:

With the Targets screen displayed, locate the Global Mass Targets table and click Add.
In the Target Details group, select Rate per Period or Ratio, define a Name for the new target variable and click Edit to start defining the mass variables and components.
On the Edit Mass Variables screen, click Add.
On the New Mass Variable/s screen, define the Category, Destination, Element, Numerator and (for Ratio target types only) a Denominator.
Back on the Edit Mass Variables screen, click OK.
Back on the Targets screen, click Apply.
In the Target Bounds group, add at least one set (row) of End Period, Minimum and Maximum parameters, click Apply.

Activity Steps:

Display the Global Targets screen.
In Global Mass Targets, select an existing target to view its details in Target Details and Target Bounds.
To add a new target, select Add.
To delete a target, select the target, then select Delete.
Select Use to make the target active during scheduling.
In Obj. Function, select whether the target is used as an objective function or as bounds.
In Target Details, select Rate or Ratio, then enter Name and review Expression.
To edit mass variables for the target, select Edit.
In Target Bounds, add one or more rows, then enter End Period, Minimum and Maximum values.
Select Apply to save your changes.
Select Revert to undo recent changes.