Segmented Blasthole Explosive Layers for Rock Fragmentation
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Solution Overview
Problem
Conventional blasting methods in mining face limitations in achieving high explosive energy concentrations due to safety constraints related to flyrock, excessive vibration, and damage to surrounding infrastructure, which restricts the improvement of rock fragmentation and comminution efficiency.
Innovation Solution
A method involving a high energy blast zone with a high explosive layer and a low energy layer, where the low energy layer acts as a protective blanket to contain the explosive energy, allowing for higher powder factors up to 20 kg/m3 in the high energy layer while maintaining safety by using a low energy layer with a powder factor at least two times lower, achieved through sequential blasting and strategic placement of explosives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high explosive energy concentration is used to improve rock fragmentation, then productivity increases, but flyrock and damage to surrounding structures occur
Solution Approach 1:
The blast zone is segmented into multiple layers with different explosive energy concentrations. A high energy layer (powder factor ≥1.75 kg/m³) is placed adjacent to the free face for effective rock breakage, while a low energy layer (powder factor <1.75 kg/m³) is positioned between the high energy layer and surrounding rock to contain explosive energy and prevent flyrock and structural damage.
Solution Approach 2:
Different regions of the blast zone are assigned different explosive energy characteristics. The high energy layer provides intense fragmentation where needed, while the low energy layer provides energy containment in adjacent regions, creating a spatially varying quality distribution that simultaneously achieves both productivity improvement and safety.
2Productivity
If high powder factor is used to achieve improved fragmentation, then comminution performance increases, but excessive vibration and noise occur
Solution Approach 1:
The explosive charge is segmented into high and low energy layers that control the spatial distribution of vibration and noise generation. The high energy layer produces the necessary fragmentation and comminution effects, while the low energy layer acts as a buffer that reduces the propagation of excessive vibration and noise to surrounding areas.
Solution Approach 2:
The low energy layer, which could be considered wasted explosive energy, is converted into a beneficial energy containment barrier that reduces harmful vibrations and noise while still allowing the high energy layer to achieve the desired comminution throughput.
3Ease of operation
If high explosive energy is used to break waste rock, then ore access is improved, but ore-to-waste ratio decreases due to dilution
Solution Approach 1:
The blast design segments the rock mass into different zones: the high energy layer breaks waste rock to improve ore access, while the low energy layer selectively limits breakage in adjacent areas, preventing excessive waste rock from entering the ore zone and maintaining a favorable ore-to-waste ratio.
Solution Approach 2:
Different local zones are given different explosive energy treatments. The high energy layer provides aggressive breakage where waste removal is needed, while the low energy layer provides gentle breakage in zones where waste control is critical, creating a spatially differentiated approach that maintains ore quality.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables improved rock fragmentation and increased mining productivity while safely containing the explosive energy, preventing flyrock and damage to surrounding structures, thus enhancing the efficiency of rock breakage and comminution processes.
Implementation Method 1
loading the blastholes with a first explosive to provide a high energy layer of the high energy blast zone having a powder factor of at least 1.75 kg of explosive per cubic meter of unblasted rock
Implementation Method 2
loading at least some of those blastholes with a second explosive to provide a low energy layer of the high energy blast zone between the high energy layer and the adjacent end of those blastholes
Data Source
AI summary
A method of blasting rock, in mining for recoverable material, comprising drilling blastholes in a blast zone loading the blastholes with explosives and then firing the explosives in the blastholes in a single cycle of drilling, loading and blasting. The blast zone comprises a high energy blast zone in which blastholes are partially loaded with a first explosive to provide a high energy layer of the high energy blast zone having a powder factor of at least 1.75 kg of explosive per cubic meter of unblasted rock in the high energy layer and in which at least some of those blastholes are also loaded with a second explosive to provide a low energy layer of the high energy blast zone between the high energy layer and the adjacent end of those blastholes, said low energy layer having a powder factor that is at least a factor of two lower than the powder factor of said high energy layer. The high energy blasting method provides improved rock fragmentation through increased explosive energy concentration while simultaneously alleviating deleterious environment blast effects.