The mining industry is constantly evolving, and we must adapt and meet the challenges of the new era. Airdecking, once considered a fringe concept, proves conventional practices can be rethought.
FREMONT, CA: Technological advancements, specifically our ability to track blasting data, have led to greater understanding and improved blasting techniques. Airdecking is one such technique that has received considerable attention over the past decade. Primarily for its efficiency gains in applications seeking to enhance fragmentation, reduce vibration, and optimize explosive use.
Although the concept is widely accepted in Southern America and Australia, it is not universally understood and, in some cases, rejected—frequently for this reason. Airdecking as a blasting technique is gaining a substantial foothold in mainstream thought as science continues to develop and as more and more operations pursue greater productivity.
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The idea of an airdeck
As its name implies, an airdeck is void of air created in the column of a blasthole within or between the loaded explosives and above them. This air column is intended to create a space where explosive gases can expand, resulting in a more uniform distribution of explosive energy over a larger area and a more powerful explosion.
Incorporating an air deck into a conventional explosive column allows the blast energy to be redistributed and optimized for the desired application.
Airdecking for better fragmentation
The size and placement of an air deck within a blasthole serve as adequate controls, shaping the energy distribution. By maintaining the same amount of explosives but introducing an airdeck, the explosive energy will act over a longer length of the blasthole and surrounding rock, improving fragmentation in previously less exposed areas to the fragmentation power of the explosives.
In addition, research indicates that airdecks can result in the reflection of shock waves, amplifying the strain wave and contributing to the enhanced brittleness caused by the constructive interference of pressure waves. Studies have shown that the airdeck can be positioned at the explosive column's bottom, middle, or top, with varying results and benefits.
Airdecks typically resulted in a 15-30 percent reduction in rock size in the targeted area when successfully applied in geologically suitable environments. Improving fragmentation can increase an operation's capacity to process greater volumes of material more quickly by facilitating faster material recovery, which is facilitated by better digging and hauling and by enhancing crushing efficiency.
Highwall protection: miner safety and survival
The airdeck technique has also been utilized in surface mining to minimize pit wall damage. Trim blasts using airdecks in the batter rows have demonstrated less fracture and shallower cracking beyond the pit wall after the blast. Less overall damage is essential for two reasons: walls that are intact and in good condition are less likely to fail, reducing the safety risk to personnel and equipment.
With fewer stress points in the wall, wall-bearing loads are improved, allowing operations to excavate more profoundly and, in effect, extending the mine's lifespan by optimizing the strip ratio. For instance, in 2018, a Chilean copper miner, like so many others, began experimenting with modified blasting techniques for precisely this reason. It recognized the commercial risk and sought to mitigate it by implementing a high-wall protection plan compatible with its current procedures.
The results of a self-developed system led to improvements of up to 70 percent and 90 percent, respectively, in crucial conditioning and design factors.
