Three ways to eliminate fines in blasting

By |  March 3, 2022
The two blast patterns seen here illustrate the differences in burden and spacing based on sequencing of the blast. Photo: Anthony Konya

The two blast patterns seen here illustrate the differences in burden and spacing based on sequencing of the blast. (Click to enlarge) Photo: Anthony Konya

This can be taken a step further when the site begins to analyze firing a staggered pattern. The sequencing of the blast will typically have a larger impact than the actual physical drilling approach used. This now becomes a complex process of designing the proper burden, spacing and timing; then laying out the blast on the actual bench and sequencing it; and then recalculating the burden and spacing to ensure that the blast’s true burden and true spacing on every hole are appropriate and to the original design.

If they are not, then the sequencing or physical layout of boreholes must change so that when a blast is fired, the true burden and true spacing are always the same. This develops consistent and reliable performance over time that can then be modified and optimized. Without the consistency that designing to true burdens and spacings brings, the process will be variable and making design changes will lead to little or no performance because the actual blasting practices change for every blast.

3. Measuring the full system

Another way to fight fines is to ensure that the fragmentation is measured – not only for the blast, but for every part of the mining process.

This is a system in which fragmentation can be fully optimized through long-term engineering and design processes. Systems for monitoring fragmentation are readily available and constantly improving. Recently, we have seen systems for fragmentation monitoring introduced, allowing for the conglomeration of fragmentation data from immediately after a blast, to the fragmentation in loader buckets, to the fragmentation measurements on conveyor belts. These systems, combined with good engineering practices, can give tremendous insight into reducing fines through the entire handling process.

With these systems, each site can develop a critical feedback loop that analyzes the percentage of fines – such as the percent of material passing a No. 4 sieve – to determine the best fragmentation curve from the blasting process.

For example, let’s say a site monitors fragmentation after the blast, after the primary crusher and after the secondary crusher. The site clearly sees a trend showing that 50 percent of the material going through the secondary crusher under 1/2 in. is turned into fines – and that this is the largest source of fines production in the process.

The next stage is to understand how to increase the amount of material above 1/2 in. from the primary crusher. The site can tell, after a long-term monitoring process, that material whose fragmentation curve has more than 30 percent of material less than 3 in. will result in a significant increase in the 1/2-in.-diameter product leaving the primary crusher.

In this situation, the site can now clearly see that it needs to blast material to larger than 3 in. in diameter to significantly reduce fines through the remainder of the process. This also presents blast engineering certain requirements it can design to and optimize around that are more critical than just reducing the amount of fines generated in the blasting process.

In practice, this process is more complex than illustrated due to large variability in fragmentation curves and response. But the example provides an illustration of the engineering that should go into the process of fighting fines.


Aggregate operations are constantly fighting fines from the blasting process, and the reduction of them is typically of the highest concern to a site’s blasting engineer.

There are many methods to manipulate a blast design in order to eliminate fines from blasting, including the use of proper spacing and sequencing of a blast to ensure the correct blast design is implemented.

Still, in order to truly reduce the amount of fines in blasting, an engineer will require a detailed understanding of how fines are generated through the entire process. This allows for the engineer to understand the desired fragmentation curve requirements for the blasting process, which lead to long-term performance increases.

Anthony J. Konya is the vice president at Precision Blasting Services, consulting around the world in rock blasting and vibration from blasting. He is also the founder and CEO of Academy Blasting, an explosive engineering education company, and the host of the AcademyBlasting.TV podcast.

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