BlastCast Guide

Introduction to BlastCast

BlastCast is a WipFrag tool for comparing measured fragmentation with a predicted particle size distribution based on blast design and loading parameters.

The basic workflow is: Measure   →   Calibrate   →   Predict

First, analyze the fragmentation from a completed surface blast in WipFrag. Enter the parameters that were actually used for that blast and use them to calibrate the Rock Factor. Once calibrated, keep the Rock Factor fixed and adjust the controllable blast parameters to see how the predicted particle size distribution changes.

BlastCast displays two curves:

• Blue – Measured Fragmentation: The particle size distribution measured from the completed blast in WipFrag.
• Red – Predicted Fragmentation: The particle size distribution calculated by BlastCast from the current model inputs.

Changing the blast parameters moves the predicted curve. Your measured WipFrag result remains the reference. For help reading the measured PSD, D-values and other standard WipFrag results, refer to the Results Interpretation Guide.

What BlastCast is for

Use BlastCast to:

• compare predicted fragmentation with measured surface blast results;
• calibrate the prediction to local rock conditions;
• explore changes to burden, spacing, hole diameter, explosives, and other blast parameters; and
• compare possible blast scenarios before applying changes in the field.

BlastCast is a prediction and comparison tool. It does NOT replace blast design procedures, engineering judgement, site standards, or the requirements of qualified blasting personnel.

REMEMBER

BlastCast is designed for surface blasts. It can NOT be used to predict fragmentation for underground blasts.

1. Before You Begin

BlastCast works best when it starts with a representative WipFrag analysis and reliable information about the blast that produced it.

Before opening BlastCast, have the following ready:

• A completed WipFrag fragmentation analysis
  • Use representative images from the blast and complete the analysis as normal
• The actual blast parameters
  • Use the values that were used in the completed blast — NOT planned values that differ from what was actually drilled or loaded
  • You will need:
    • Bench Height
    • Burden
    • Spacing
    • Hole Diameter
    • Drill Accuracy
    • Relative Weight Strength
    • Explosive Density

BlastCast will use these values together with the measured fragmentation to establish the Rock Factor for the model.

REMEMBER

Calibrate from what actually happened. The measured fragmentation and the blast parameters entered into BlastCast should describe the same blast.

Use reliable source values

Use drill and blast records wherever possible.

For explosive properties such as Relative Weight Strength and Density, use the applicable manufacturer’s technical data rather than estimating the values.

2. Calibrate BlastCast to Your Current Blast

Step 4 – Check the calibration

Once the actual blast parameters have been entered, compare the predicted red curve with the measured blue curve.

Step 5 – Lock the Rock Factor

When the current blast has been entered and calibrated, turn the Rock Factor Auto setting OFF. This locks the calibrated Rock Factor.

Do NOT continue recalibrating Rock Factor while testing design changes. The purpose of the next step is to hold the rock condition constant while changing the controllable blast inputs.

CALIBRATION COMPLETE

You now have a BlastCast model tied to the measured fragmentation and conditions of the completed blast.

3. Test Changes to Blast Parameters

Once Rock Factor has been calibrated and locked, use BlastCast to explore how changes to controllable parameters affect the predicted fragmentation.

Adjust a parameter and watch the red prediction curve

The blue measured curve stays in place as the reference from the completed blast.

Start with one change at a time

When learning how a parameter affects the prediction, change one input at a time.

For example: Current Spacing   →   Adjust Spacing   →   Compare Prediction

This makes it easier to see which parameter caused the change in the predicted PSD.

Once you understand the individual effects, combinations of realistic changes can be tested together.

Compare against the result you want

Do NOT judge the prediction only by whether the entire curve moves finer or coarser.

Consider the particle sizes that matter to the operation, such as:

• desired D50 or D80;
• maximum acceptable fragment size;
• crusher feed requirements;
• oversize limits; or
• another operational PSD target.

BlastCast is most useful when the simulation is tied to a specific operational objective rather than simply trying to make fragmentation “smaller.”

Keep Rock Factor fixed

If the purpose is to compare blast designs under the same rock conditions, leave the calibrated Rock Factor unchanged while testing the other parameters.

If the rock mass changes materially, do NOT assume that a Rock Factor calibrated in one geological condition automatically represents another. Recalibrate using a representative measured blast from the new conditions.

4. BlastCast Parameters Explained

Parameter	Description	What to enter in BlastCast
Bench Height	Vertical height from bench floor to crest.	Actual bench height for the blast.
Burden	Distance from a blasthole to the nearest free face; for interior rows, generally the row-to-row distance.	Actual burden used.
Spacing	Distance between adjacent blastholes in the same row.	Actual hole spacing used.
Hole Diameter	Nominal diameter of the blasthole.	Hole diameter used for the blast.
Drill Accuracy	Represents deviation from the intended hole position, alignment and trajectory.	A representative value for the drilling accuracy achieved.
Relative Weight Strength	Explosive energy per unit mass relative to ANFO = 100.	Manufacturer’s RWS value.
Explosive Density	Mass of explosive per unit volume.	Loaded density in g/cm³ or equivalent.
Rock Factor	Calibrated parameter representing the influence of the rock mass on fragmentation.	Auto-calibrate from the measured blast, then lock.

IMPORTANT

Rock Factor is NOT simply another design slider. It represents the rock conditions against which the blast model is being calibrated.

5. Using and Interpreting the Prediction

BlastCast is most useful as a comparison tool.

The red curve does NOT represent a measured future result. It represents the fragmentation predicted by the model from the parameters currently entered.

Use the prediction to compare scenarios and understand the direction and scale of the modeled change.

BlastCast Quick Reference

Before calibration

• Complete the WipFrag fragmentation analysis.
• Confirm the analysis represents the blast being modeled.
• Gather the actual drill and blast parameters.
• Confirm the explosive RWS and Density.
• Select the correct units.

Calibrate

• Open BlastCast.
• Enable Auto Rock Factor.
• Enter the current blast parameters.
• Confirm the measured and predicted curves.
• Allow Rock Factor to calibrate at X50.
• Turn Auto Rock Factor off to lock the value.

Predict

• Keep Rock Factor fixed.
• Adjust the parameter you want to investigate.
• Review the change in the red prediction curve.
• Compare the predicted PSD with the operational target.
• Record the scenario being considered.

After the next blast

• Analyze the resulting fragmentation in WipFrag.
• Compare the measured result with the prediction.
• Recalibrate when appropriate before testing the next design.

MORE INFORMATION

For detailed WipFrag software controls and the technical basis of the prediction model, refer to the latest WipFrag User Manual and the KCO Blast Model document available within BlastCast.