Multi-blast charge all holes
This function allows for the charging / blasting of long sub-vertical holes in a number of distinct phases. It provides similar functionality to Charge All Holes but is enhanced through the ability to define multiple blasts using different zones from the same ring of blast holes.
To run this function: Choose Design > Ring design > Charging > Multi-blast charge all holes, or...
If a design area has already been selected, you will be prompted for the names of the current drive and stope outlines with the CURRENT POSITION INFORMATION form.
Stope
The name of the current stope outline.
Drive
The name of the current drive outline.
If no drive has been selected, or the CURRENT POSITION INFORMATION form was applied, the Multiblast Charge All Holes function will display the prompt:
Select the first hole to be charged
Select the first hole to be charged. The Multi-blast Charge form is displayed.
Define blast zones by
Specify whether the blasts are to be delineated by an elevation range or a set of graphically selected segments.
Elevation range
If you selected to define blasts by an elevation range, you will need to enter the range.
It is assumed that the charge closest to the end of the blast holes is fired first with other charges fired in sequence until the charge closest to the collar is blasted as the last blast. This restricts this technique to a practical application of only being used for sub-vertical holes in a cut and file type stoping operation. Since the delimiting elevations are applied against the Z coordinates of the holes, this function cannot be used for horizontal sections or sections not taken in real-world coordinates.
For example, entering an elevation range of 1000;1010 would define the first blast as being from the toe of the blast holes up to the elevation 1000. Any holes whose toe ends at an elevation greater than 1000 will not be charged. This will be the first blast for the ring.
Those blast holes that span the 1010 to 1000 elevation band will be charged between the elevation limits. This will be the second blast for the ring.
Those blast holes whose collars are greater than 1010 will be charged down to the 1010 elevation.
If selected segments are being used to delineate the charging for the different blasts, on Applying the form the user will be prompted to select segments that delineate the blasting zones:
Select the segments delimiting the blasting zones. Press (ESC) to finish
Apart from using selected segments to delineate the blasts zones, the logic is identical to when elevations are used to selected blast zones.
All the holes drilled from the drive of the selected hole into the stope of the selected hole will be charged in clockwise order around the drive starting with the this hole. The method used for determining stemming and total charge length is specified on the Charging Parameters form.
If, for any of the blasts, the charge length is less than the minimum charge length that portion of the hole is not charged. Subsequent charges in the multiblast ensure that the offending portion of hole is charged even though it may fall marginally outside the charge boundaries delineated by the elevation or digitised blast zone boundaries.
For each blast, a segment (of 2 points) is created in each string (which represents a blast hole), where the length of the segment represents the portion of the blast hole that has been charged. It is possible that some blast holes may not be charged for some of the blasts because the minimum charge length is not exceeded. If this situation occurs then a segment representing the charge is still created. The segment will however have zero length with the coodinates being at the toe position of the hole or at the top of the last blast zone. These segments are used when charging the next blast to determine the limit of charging of the last blast.
By ensuring that one segment exists to represent the charge length in each hole, even if a hole is not charged for a given blast, it makes it possible to plot the length of charge for different holes in different colours even if the hole has no charge for a particular blast.
Warnings
This function requires an existing hole
If no holes have been drilled, no holes are available to be charged.
The calculated charge length for hole aaa is shorter than the specified minimum charge length.
The named hole has not been charged because the calculated charge length is shorter than the minimum specified on the Charging Parameters form.
The selected hole has already been charged
One of the holes in the ring alredy contained a charge segment.