Process Blend

Use the Process Blend constraint to optimise the blend as a part of the value maximisation process. Process Blend is a soft constraint, so violating it will not cause a schedule to be invalid. When evaluating a schedule, Evolution checks how far the blend values are outside the specified range and then selects a schedule focusing on the blend result, rather than giving the priority to the net present value (NPV). You can select either a non-ratio or ratio blend, as well as the type of weighting applied to the blend.

Note:  The Process Blend constraint is a soft constraint, which means that Evolution will try to meet it when generating a schedule, but doing so is not forced.

Follow these steps to create a blend constraint:

1. Using the drop-down menu, select the process that requires a blend.

2. Configure the constraint. The possible configuration settings are as follows:

   • Control the blend of a single grade item.

     Note:  This is weighted by the Ore Capacity (tonnes) attribute set in the Tonnage & Grade.

     Expand for more information.

     1. Ensure that the Is Ratio? checkbox is not selected.

     2. Select a grade item using the Item drop-down menu.

     3. Set the range for mill processing by determining the upper and lower limit value under the Blend section of the table.
        

        

   • Control the blend ratio between two grade items.

     Note:  This ratio can be weighted by any numeric block attribute from models in the setup.

     Expand for more information.

     1. Select the Is Ratio? checkbox.

     2. Select the appropriate variables in the Numerator, Denominator, and Weight drop-down menus.

     3. Set the range for mill processing by determining the upper and lower limit value under the Blend section of the table.
        

        

   • Control the blend of a single grade item with a unique weight attribute.

     As you cannot select a unique Weight when the Is Ratio? checkbox is deselected, the following steps allow you to create a blend for a single grade item with your choice of weight attribute.

     Expand for more information.

     1. Select the Is Ratio? checkbox.

     2. Select the attribute you wish to control the blending of using the Numerator drop-down.

     3. Create a new denominator attribute with the value of 1. You can do this by entering the following into a maths script:
        

        
        

        See Maths Scripts for Block Models for more information on creating new attributes.

     4. Select this new denominator attribute using the Denominator drop-down.

     5. Select a weight attribute using the Weight drop-down.

3. In the calendar, under Blend, enter the Upper and Lower blend constraints. If Is Ratio? is selected, this value is a ratio.

• Click the button once to copy the properties of the current period to the next period.

• Double-click the button to copy the properties of the current period to the subsequent periods until the end of the schedule.

• Alternatively, copy a cell's setting by pressing Ctrl+C , then paste it into selected cells with Ctrl+V.