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Application:
- BlastIQ™ Underground Desktop
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Version:
- 1.1.13 and above
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KBA Summary:
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This Knowledge Base Article describes the different density modes for Subtek™ bulk explosive products within the BlastIQ™ system.
Introduction
There are two methodologies used to calculate the mass of Subtek™ underground bulk explosive products in BlastIQ™. These methodologies are ‘Nominal Density’ and ‘Calculated Density’. This Knowledge Base Article describes the different methodologies.
All bulk explosives in the BlastIQ™ System are assigned a nominal density. This nominal density is the 'target average in-hole density’ for a bulk explosive product when loaded, regardless of length.
When using the ‘Nominal’ methodology, charge mass for Subtek™ explosives is calculated by multiplying the volume of an explosive column by the specified nominal density. This is described by the following formula:
(π x r² x L) x ρ n
Where:
- r = Hole Radius or (Hole Diameter / 2)
- L = Charge Length
- ρ n = Nominal Density
Nominal Density Behaviour
When using the nominal methodology, bulk explosives charge mass can be calculated from a given charge length, or charge length can be calculated from a given charge mass.
No allowance is made for ‘gassing’ when using the nominal density methodology.
Figure 01. Nominal Density Product as show in BlastIQ™ Underground Desktop.
Figure 02. Nominal Density Product as shown in BlastIQ™.
Because ammonium nitrate emulsion (ANE) based bulk explosives are compressible and experience hydrostatic pressure, the density of an explosive column is not constant along the length of the column. The density of explosives is affected by the following properties:
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Hole Diameter.
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Hole Orientation (angle and bearing).
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Explosive Yield Stress.
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Bulk Explosive Temperature.
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Explosive Deck Length.
Where Subtek™ explosives are configured to use the 'Calculated density' methodology density is calculated for each deck individually (independent of other decks within a hole) based on explosive and hole properties.
This calculated density is then used to calculate the charge mass of the deck, as described by the following formula:
(π x r² x L) x ρ c
Where:
- r = Hole Radius or (Hole Diameter / 2)
- L = Charge Length
- ρ c = Calculated Density
Calculated Density Behaviour
For products using the ‘Calculated’ methodology, bulk explosive charge mass can be calculated from a given charge length, or charge length can be calculated from a given charge mass.
Additionally, the following is calculated for each deck:
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Ungassed Length.
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Ungassed Horizon.
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Expansion Factor.
Calculated density is only applicable for Subtek™ gassed bulk explosives.
Figure 03. Calculated Density Product as show in BlastIQ™ Underground Desktop.
Figure04. Nominal Density Product as shown in BlastIQ™ Mobile.
Product Configuration
Calculated density can only be used for products with the correctly populated properties. To enquire about products with calculated density, please contact BlastIQ™ Support.
Site Configuration
To enable calculated density, users must have ‘Admin’ permissions.
To enable Calculated Density for a BlastIQ™ Site:
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Navigate to BlastIQ™ Admin.
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Select ‘Products’ from the sidebar.
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Select ‘Enable calculated density’.
- Select 'Edit'
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Populate the Initial and Final Temperatures for the site with the correct Initial and final Ammonium Nitrate Emulsion Temperature for the site.1
- Select 'Save'.
Information
- If initial and final temperatures are not known, values of 40° and 20° are recommended for initial and final temperatures respectively.
Critical density occurs when the density of Subtek™ bulk explosive within a charged hole exceeds the designed operating parameters. In BlastIQ™ critical density for the SubTek™ product range are dynamic and can be influenced by the design. If the charge design exceeds the recommended product ranges for hole diameter range (See Figure 05), or the gassed charge length (refer to Figure 04), BlastIQ™ will flag critical density.
Figure 05. Product Range for calculated density hole diameters.
Impact of Critical Density
Exporting to BlastIQ™
When the design is affected by critical density users will be unable to export the design to BlastIQ™ until the issue has been rectified.
Figure 06. Error message when attempting to export to BlastIQ™ when critical density is present.
Critical Density Interfaces
Users can view holes affected by critical density through several interfaces
- Warnings: Automated alerts will be displayed in the bottom right of the screen if critical density is detected.
- Data Table: The blast's data table will highlight entries with densities which exceed the critical threshold.
- Edit Hole Loading Dialog: In both BlastIQ™ Underground and BlastIQ™ the hole loading dialog will display error messages when critical density occurs.
Figure 07. BlastIQ™ Underground edit hole loading dialog.
Figure 08. BlastIQ™ loading holes dialog.