Our client, a coal miner in the Powder River Basin, was struggling to address high blasting costs. In an effort to reduce blasting costs, they engaged an independent consultant and conducted blast tests. They hoped to find innovative solutions, such as reducing explosives use, while still maintaining operational efficiency.

The blasting process used a 50/50 emulsion mixture as the primary explosive. The stemming height reached 16.15 meters to ensure effective detonation. Each blast hole was equipped with two electronic detonators to ensure safety and consistency during blasting.

By implementing a conventional blast design, they achieved an average powder factor of 0.42 kg/m3. The powder factor is an indicator of the efficiency of explosives use; the lower the number, the more efficient the use of explosives and blasted material.

Our client aimed to achieve a significant difference between the use of an air deck and its absence in the blasting process. The ultimate goal was to develop a solution that would reduce blasting costs, increase operational efficiency, and optimize production output.

To reduce the use of explosives, they decided to use an air deck between the stemming column and the explosives. In this context, they chose to use MTi BLASTBAG™ placed in each hole to form the air deck.

As seen in the illustration above, 4 test blasts were conducted sequentially, applying 3 different decking designs to reduce the explosive column by 0.9 meters in the first 2 designs and 1.5 meters in the last design. Different air deck designs were applied to different parts of each test blast to allow for valid comparison of results.

In all their blasting tests, the resulting Velocity of Detonation (VOD) remained consistent with the use of bulk explosives and produced comparable blasting performance. Rock fragmentation was unaffected, as were the charge and cycle time required to excavate the blast waste.

From the results of the third blasting test, they successfully achieved a powder factor reduction of 0.38 kg/m3. This result was then replicated and validated in the fourth blasting test.

Conclusion

This study confirms that the use of a well-designed air deck does not negatively impact blasting performance, and notes that the additional time required to set up the BLASTBAG™ is insignificant and negligible.

It is important to note that the powder factor reduction can be achieved without compromising the overall effectiveness of the blasting process. This offers significant potential cost savings for the mine site, with an estimated reduction in explosive consumption of up to 5,300 tons per year, equivalent to a savings of approximately USD 1.6 million per year. All of this highlights the positive benefits of using the MTi BLASTBAG™ in overburden blasting processes in mines.

Don’t hesitate to contact us for further information; we’ll be happy to answer your mining blasting needs.