Mass of Explosives

The Mass of Explosives field in the Drillholes Summary tab of the Plot Options form reports the total mass of all explosives that occupy a hole. The mass is reported in kilograms. The following formulas are used to calculate the mass of explosives:

Load Factor (kg/m) = [(D2 x d x 0.785)]/1000

Where:

  • D = Charge Diameter (mm)

  • d = Explosive Density (g/cc)

Given the Load Factor, the charge weight can be calculated using the below formula:

Mass of Explosives (kg) = Charge Length (m) x Load Factor

Note

For packaged explosives, the Charge Diameter (D) will be based on the diameter of the product as specified in the Consumables Library. For bulk explosives, the diameter of the blasthole will be used for the Charge Diameter.

The Density of each explosive product as specified in the Consumables Library will be used in the calculations. The calculated value will be recalculated and updated (upon selection of a hole/s) if changes are made to a property for a consumable.

For all explosive products, the Charge Length used in the calculation is based on the interval length(s) as specified in Edit Charge Templates configuration.

Costs

Cost values in the Consumables Library will be used to calculate the total costs associated with the use of each consumable of a given round. The calculated costs are written to the Consumables table which can be added to a plot. In addition to this, unit costs (cost/item) for detonators, boosters and connectors are written to the Collar and Event files when the Export to Drillhole Database tool is used. The total cost associated with the use of explosives or other consumables in each interval are calculated and reported in the Interval file. See Cost of Material below.

Charge Concentration

This value is reported for intervals containing an explosive using the following formula.

Kg Of Explosives per metre of blasthole = (π X D2 / 4) X Density of Explosives / 1000

Where:

  • D is the Diameter of a hole in Millimetres in a bulk explosive. In the case of packaged explosives, the diameter is based on the diameter of the packaged explosive as specified in the consumables library.

  • Density of explosive is expressed in g/cm3

Once the charge concentration is known, the Power Factor (the weight of explosive used to break and loosen each m3 or tonne of rock) can be calculated for a known volume of rock.

The powder factor can now be calculated by dividing the volume of rock into the total explosives per blasthole.

Powder Factor (kg/m³) = Total kg of explosives per blasthole / Volume of rock per hole

This will give you the powder factor for a given hole. To calculate the powder factor over an entire blast, multiply the volume of rock for one hole by the total number of holes and divide into the total kgs of explosives used in the blast.

If you wish the powder factor to be in tonnes rather than volume of rock, divide the powder factor calculated by the density of the rock.

Powder Factor (kg/tonne) = Powder Factor (kg/m³) / Density of Rock

Cost of Material

This value is calculated given the mass of a material, and the cost as specified in consumables library.

Cost = Explosive Mass [kg] * Explosive Cost [$/t]

In the case of packaged explosives, the reported cost will be based on the interval length that a packages product occupies. This method ensures that the calculation to properly deal with cases where the entire length of a packaged explosive is not used, for example tamped cartridge.

Cost = [Package Length (mm) / interval Length (m)] X 1000 X Explosive Cost ($/item)

Where multiplication by 1000 is used to convert interval length from meters to millimetres.