iGantt Optimizer Tutorial for Underground

Minemax Tutorial iGantt Optimizer for UG Minemax 1998 2013 Page 1 of 24

Minemax Tutorial

iGantt

Optimizer

for

Underground

Version: 4

Updated: May 2013


COPYRIGHT NOTICE

2013

Copyright in this document is vested in Minemax Pty Ltd.


1. INTRODUCTION

1.1 Purpose

The purpose of this tutorial is to demonstrate the use and the functionality of iGantt

Optimizer for short-term up to long-term detailed scheduling for Underground applications.

2.1 Prerequisites

The prerequisite knowledge for this tutorial is an intermediate level of proficiency using

iGantt software to:

Create an iGantt project (attributes, activity types, calendars, report items and

reports)

Load visualization from strings and triangulated surfaces and format the 3D view

Import and map activities

Create precedences for activities

3.1 Scenario

The scenario used for this tutorial is an underground project for scheduling of production

activities (stoping and drifting) and development activities (access, ventilation, ramp) with

locations within multiple levels. Back-filling activities that typically follow production activities

for underground applications have not been considered in this scenario.

The iGantt Optimizer can be used for short-term scheduling on a monthly or a quarterly

basis as well as for long-term scheduling on a yearly basis. In this project, we will develop a

long term 9-year schedule to schedule the entire deposit by maximizing the profit while

satisfying development and mining constraints. As a subsequent step, we will then assign a

resource to development activities and level the resource using the Auto-scheduling module

of iGantt.

The development activities have a constraint of 1,300 development metres annually. The

total material mined has a fixed capacity of 80,000 tonnes annually. (The total tonnes used

for demonstration purposes of this tutorial might not represent the typical values used in

underground applications.)

Apart from the standard location and physical attributes such as tonnes, development

metres and grades, the revenue, mining, processing and development costs are modelled in

this scenario.


2. TUTORIAL STEPS

1. From your Windows Start menu, click All Programs iGantt Tutorials

Tutorial Files Optimizer Underground to navigate to the tutorial file

demotutorial_iGantt_Optimizer_UG.igt. Double-click on the file to load the project into

iGantt displaying activities, 3D visualization and the default report on a single screen.

TIP: If you are a Windows 8 user, right-click the Windows Start screen to view the bottom bar with the All Apps icon. Click on the All Apps icon and then click Tutorial Files Optimizer Underground to navigate to the tutorial file demotutorial_iGantt_Optimizer_UG.igt.

2. Click the Project menu and then select Project Attributes to view attributes

previously defined for this project. Click the OK button to exit.


3. Click the Project menu and then select Activity Types to view activity types

previously defined. In this project, we have two activity groups defined. The Production

activity group consists of Stoping and Drifting activity types. The Development

activity group consists of Access, Ventilation and Ramp activity types.

4. Click the OK button to exit.


5. Click the Project menu and then select Edit Project Calendar to view the current

project calendar. The iGantt Optimizer requires the default calendar 24 hours, 7 days

with no non-default days.


TIP: If a non-default project calendar is detected by iGantt Optimizer, a warning

message will appear with the option to remove all non-default days or times by

clicking the Fix Schedule Automatically button.

7. Click the Resources menu and then Edit Resources to view the Resources

window. For this project, one development resource has been set up with the rate of 3.5

m/day.

8. Click the Close button to exit.

9. Click the Reports menu and then Define Reports to view details about the

Summary report by selecting the Edit Report button. The Summary report includes

summary items for Ore Tonnes, Au Grade, Waste Tonnes, Total Tonnes, Trucks and

Financials per time period.



11. Click the Optimizer menu, select Options and then click the Time Periods sub-

menu to specify the time periods for the optimization.

11.1. Click the Edit in Advanced Mode button.

11.2. Change the start time to show 01/07/2013 and then enter the value 9 into the

Number of Time Periods field. This will generate nine time periods.


12. Click the Constraints sub-menu to add constraints for our project. In this scenario, we

will constrain the total tonnes and development metres.

12.1. Click the New button to add a new constraint. This will open up the Add

Constraint window displaying the Details sub-menu.


12.2. Type the name of the constraint Tonnes in the Name field and select the

constrained attribute Tonnes from the drop-down menu.

12.3. Click the Activity Types sub-menu to select the activity type that will be

constrained. Click the Production (PRD) activity on the left and move it across

to the right area by clicking the > button. Then click the OK button.


12.4. This will create two entries for minimum and maximum tonne constraints per time

period. Enter the maximum value of 80,000 tonnes into the time periods.

TIP: Use the Copy Row Forward button to copy the required value to all

subsequent time periods.

12.5. Repeat steps 12.1 to 12.4 to add the Dev Metres constraint to the grid. Select

Dev_Metres for the constrained attribute and Development for the activity

type.


12.6. This will create two entries for minimum and maximum Dev Metres constraints

per time period. Enter the maximum value of 1,300 hours into the time periods.

13. Click the Options sub-menu to select the optimization strategy from the three

available options:

Forward scheduling optimizes one period at a time, carrying results from one period

forward to the subsequent period. This option provides a very fast result but doesnt

guarantee finding the theoretically optimal schedule.

Global scheduling considers all time periods together and can find the true optimal

schedule. If a large number of blocks and time periods are used, global scheduling

can be quite time consuming.

Sliding window scheduling optimizes x time periods at once and then moves y

time periods forward. The same process repeats in multiple interactions defined by

the x + y combination where x represents a sliding window length value and y


represents a sliding window step value. This gives a balance of solution time and

solution optimality.

13.1. Tick the Sliding window scheduling option. By default, the 2+1 option is

selected. This means that two time periods are optimized at once. After

completing an optimization phase, the result for the first time period is kept and

the window is moved forward by one time period to optimize the next two time

periods. This process repeats until the schedule for the last time period is found.

13.2. Confirm that the Reset rates to defaults option is ticked. This option will replace

any manually added activity rates with the default rate which has been set for the

activity type.

13.3. Confirm that the Adjust rates to fit periods option is ticked. If your target is not

reached within the time period set while using the default rates, this option will

increase the rate to ensure the target value is reached within the specified time

periods.

13.4. Select the attribute Profit from the Value drop-down menu. By doing so, iGantt

Optimizer will optimize the schedule by maximizing the profit of the project.

13.5. Click the OK button.

13.6. The attribute Profit is a calculated attribute that has been previously defined

under Project Attributes by selecting the Project menu.


TIP: Other attributes can be used as a Value parameter as required. For

example, if Tonnes are used, iGantt Optimizer will optimize the schedule by

maximizing total tonnes for the project.

14. Click the Optimizer menu and then click Optimize. This will open up an Optimize

window showing the first and last periods to optimize. The dates of the first and last time

periods flow through from the Time Periods sub-menu set up previously.

TIP: Tick the Apply tick-box if you need to change the first or last period to

optimize.

15. Click the Optimize button. This will activate the optimization showing a dialog window

with the progress bar. The iGantt Optimizer uses a mixed integer linear programming

(MILP) model to represent the mine and its production constraints using a branch and

bound algorithm.

15.1. In the first step, the dialog window displays the Initializing message while

iGantt Optimizer builds the mathematical model of constraints.


15.2. In the second step, the dialog window displays the Periods 1-2: Still looking for

result message. This means that the maximum upper value (bound value) within

the first two time periods is being searched for.

15.3. In the next step, once the bound value is determined, iGantt Optimizer looks for all

possible feasible solutions within the first sliding window and compares them

against the bound value.

15.4. The message Result found within 14.59% means that the best feasible solution

so far is at most 14.59% from optimality. The iGantt Optimizer will keep looking for

all other solutions until a solution within 1% is found.

15.5. In the next step, the sliding window will move to the next period to repeat steps

15.2 to 15.3. When the best solution for the last optimization period is found, the

dialog box will disappear.


TIP: It takes approx. 1 - 2 minutes to optimize the project. The optimization time will

vary based on the optimization method selected and the number of blocks and

constraints in your project.

16. The Summary Report shows total values for each report item per time period. The

Tonnes and Total Dev Metres items meet the maximum constraint per time period set

in the Optimizer menu.

17. Click the Visualization menu and then select Set Object Colour Scheme. The

Colour Scheme Chooser window will open up and display the default mode of Colour

By Object Type.


17.1. Select Colour By Time Period from the drop down menu to change the colouring

mode to time periods

17.2. Tick the Repeat Colours tick-box to repeat the same colours every eighth time

period

17.3. Tick the Multi-Time Period Object Colouring tick-box to splits strings into the

multiple coloured sections

17.4. Tick the Show in Summary Report tick-box to show the colouring code in the

Summary report

17.5. Click the OK button. This will display the colouring mode in the visualization as

well as in the reports.

18. Click the Visualization menu and then select the View Schedule to validate the

schedule using an animation.


18.1. Tick the Show Completed tick-box to step through the remaining reserve

18.2. Select the viewing date of 01/07/2013 18.3. Select the time interval of 256 ms and then click the Run button

19. The animation steps show the progress of ramp, access and ventilation development as

well as drifting and stoping for the date of 29/02/2016.

20. The animation shows some remaining material that has not been scheduled within the

optimization periods due to economics and precedences included in this scenario.


21. Load the iGantt file demotutorial_iGantt_Optimizer_UG_optimized to compare your

results up to step 20.

22. Click the Resources menu and then select Assign Resources to assign the

Development resource to all development activities.


22.1. Click the Development (DEV) activity type to highlight it and then click the >

button. This will assign all development activities to the resource.

22.2. Click the Close button.

23. Click the View menu and then select View By > View by Resource to view

activities grouped by the Development resources. This will display utilization of the

resource at the top of the Gantt chart. Over-allocation of the resource displays in red.

TIP: The over-allocation of the resource can be resolved manually or using the Auto-Scheduling module. In the next step, we will use the Auto-Scheduling functionality to level the Development resource.

24. Click the Auto-Scheduling menu and then select Targets to add a target for auto-

scheduling.


24.1. Click the Add button and then select Start Time Target from the drop down

menu. This will ensure that the Development resource is auto-scheduled based on

the start time of the activities after the Optimization. Click the OK button to close

the Select target type dialog.

24.2. Click the Ok button.

25. Click the Auto-Scheduling menu and then select Resources to include the

Development resource for auto-scheduling.

25.1. Click the Add button and then select Development from the drop down menu

and then click the OK button. This will open up a new dialog window to specify

the rate and maximum simultaneous activities for the Development resource.


25.2. For this scenario, un-tick the Unlimited tick-box and enter 3 in the Maximum

activities field. This will ensure that the Development will work on the maximum of

3 simultaneous activities.

25.3. Click the OK button and then click the OK button to close the Edit

Scheduleable Resource screen.

26. Click the Auto-Scheduling menu and then select Options to specify the Auto-

scheduling settings. Un-tick all three tick-boxes on the screen and then click Ok button.


27. Click the Auto-Scheduling menu and then select Schedule.

27.1. This will open up a Schedule window showing the first and last periods to auto-

schedule. The dates of the first and last time periods flow through from the time

periods set up for the Summary report.

27.2. Click the OK button.

28. View the Gantt chart utilization after auto-scheduling. The over-allocation displayed in

red has been resolved.


29. The Summary Report shows the updated total values per time period.

TIP: You might notice that Tonnes and Total Dev Metres constraints are met except for the Tonnes value in 2016. This is due to the fact that we levelled development activities but not production activities. To resolve this, the production resource can be added to the project and auto-scheduled as well.

30. Load the iGantt file demotutorial_iGantt_Optimizer_UG_optimized_autoscheduled to

compare your results for steps 22 29.


3. SUMMARY This tutorial has shown you the necessary steps to develop a long-term schedule using the iGantt Optimizer. In the first steps, we reviewed project attributes, activity types and reports previously set up in the iGantt project provided. Secondly, we showed you how to set up nine time periods of variable lengths to be used for setting constraints and optimizing. In the next step, we showed you how to set up a processing constraint using total tonnes and development metres for each time period. In the following step, we discussed optimization options and showed you how to set up the value parameter that is used for optimizing. In this scenario, we were maximizing the Net Present Profit value of the entire project. Once the optimization was completed, we also showed you how to set the object colour scheme per time period and analyse results using reports and animations. In the last step, we showed you how to assign a resource to development activities and use the Auto-scheduling module to resolve over-allocation of the resource assigned. Congratulations on completing the iGantt Optimizer tutorial for Underground applications. Please contact our Minemax experts on [email protected] for additional information about the iGantt Optimizer.

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iGantt Optimizer Tutorial for Underground