kirra-docs

Charging Overview

The Kirra Charging module lets you design explosive charge configurations for every hole in your blast. You can build multi-deck charge columns with stemming, bulk explosives, packaged explosives, air decks, and boosters — then apply them across your pattern with a single click.

Hole charge details Charge details for a blast hole showing deck configuration, product assignment, and mass calculations.

What the Charging System Does

Capability Description
Deck design Build multi-deck charge columns with stemming, explosives, spacers, and primers
Four deck types Inert (stemming), Coupled (bulk explosive), Decoupled (packaged explosive), and Spacer (air bags)
Formula-driven sizing Use formulas to calculate deck lengths automatically based on hole properties
Mass-based calculations Specify a target mass in kilograms — Kirra calculates the required deck length for each hole’s diameter
Product database Maintain a CSV-based catalogue of your site’s explosive products
Charge templates Save and reuse charge designs as named rules
Swap conditions Automatically substitute products for wet, damp, reactive, or high-temperature holes
Downhole timing Calculate detonation timing for each deck within a hole
Visualisation View charges in 2D radial, 2D section, or 3D spatial views
Export Include charge data in CSV, XML, and PDF reports

Deck Types

Every deck in a charge column belongs to one of four types:

Inert (Stemming)

Non-explosive material placed at the collar or between charge decks. Common products include crushed aggregate, drill cuttings, clay, and water.

Purpose: Confine the explosive energy and prevent venting.

Coupled (Bulk Explosive)

Bulk explosive in direct contact with the hole walls. Common products include ANFO, emulsion, and slurries.

Purpose: The main charge providing the energy to break rock.

Decoupled (Packaged Explosive)

Cartridge or packaged explosive with an air gap between the package and the hole wall. Common products include packaged emulsion and boosters.

Purpose: Controlled-energy applications such as presplit or trim blasting.

Spacer (Air Deck)

Air bags, gas bags, or inert separators placed between charge decks. These create a deliberate void in the charge column.

Purpose: Modify energy distribution and fragmentation by decoupling charge zones.

Screenshot coming soon

Formula-Driven Deck Positioning

One of Kirra’s most powerful features is the ability to use formulas to calculate deck lengths and primer positions. Instead of entering fixed numbers, you write expressions that reference the hole’s properties — so a single charge rule adapts automatically to holes of different depths and diameters.

Example formulas:

Formula What It Does
30% of hole length for stemming Stemming length scales with hole depth
Hole length minus 3.5 metres Charge fills everything below 3.5 m of stemming
50 kg at hole diameter Calculates the deck length needed to deliver exactly 50 kg of explosive

Formulas are covered in detail in the Deck Builder and Products CSV Reference pages.

Mass-Based Calculations

When you specify a deck by mass (e.g. 50 kg) instead of length, Kirra calculates the required deck length using the product density and the hole diameter. This means the same charge rule produces:

The explosive mass stays constant at 50 kg regardless of hole size.

Scaling Modes

When a charge rule is applied to holes of different lengths, each deck’s scaling mode controls how it adapts:

Mode Behaviour Use Case
Proportional (default) Deck length scales proportionally with hole length General-purpose decks
Fixed Length Deck keeps its exact metre length regardless of hole length Stemming stays at 3.5 m whether the hole is 8 m or 15 m
Fixed Mass Deck recalculates its length to maintain the same mass at the new hole diameter Toe charge must always be exactly 50 kg
Variable Formula is re-evaluated using the current hole’s properties Automatic for formula-based decks

Downhole Timing

Kirra calculates detonation timing for each explosive deck within a hole, accounting for:

This lets you verify that decks detonate in the correct order and at the expected times.

Charging Visualisation

View Description
2D Radial View Colour-coded deck layout for all holes in the pattern, displayed radially around each collar
2D Section View Detailed deck-by-deck breakdown for a single hole, showing lengths, masses, products, and scaling mode badges
3D View Charge columns rendered as coloured cylinders in the 3D scene, shown in spatial context with the pattern

Charging Workflow

Here is the typical workflow for applying charges to a blast design:

1. Import or Build Your Charge Configuration

2. Select Holes

Select the holes you want to charge — individually, by entity, or by drawing a selection box.

3. Apply the Configuration

Choose a charge rule from the Charging tab dropdown and click Apply to Selected. Kirra evaluates all formulas, calculates deck lengths and masses, and renders the charge columns.

4. Review

Select any charged hole to see its deck layout in the Section View. Check that stemming, charge, and primer positions look correct.

5. Export

Charge data is automatically included when you export to Kirra CSV, Epiroc XML, or PDF.

You can also export just the charging data in four CSV formats:

Format Content
Summary Total mass, deck count, primer count per hole
Deck Detail Depths, product name, density, and mass per deck per hole
Primers Detonator, booster, and downhole delay details
Timing Surface delay, downhole delay, and total fire time per deck

Terminology Reference

Term Definition
Collar Top of the blast hole (start point)
Toe Bottom of the blast hole (end point)
Grade Floor elevation where the hole intersects the bench floor
Stemming Inert material at the top of the hole
Coupled Explosive in direct contact with the hole wall
Decoupled Packaged explosive with an air gap to the wall
Spacer Air bag or inert separator between charge decks
Primer Detonator assembly (detonator + optional booster)
Booster High-explosive cartridge used to initiate the main charge
Deck One loading zone in the hole (one material or product)
Multi-Deck Configuration with multiple charge zones separated by inerts or spacers