Consulting ServicesAdvanced TechnologyIndustry RelationshipsTechnical Library
The Enterprise Solution to Integrating Blasting into the Mining ProcessDevelopments with Electronic DetonatorsExplosives Malfunction in Decked BlastsGeologic Considerations in Blasting and Mine SafetyMeasurement Technology in MiningBenefits of Blend Programs in Surface CoalBulk Loading of Emulsion Explosives in Shaft SinkingA Statistical Approach to Integrating Blasting into the Mining ProcessDynoMiner APS Underground Explosive Loading SystemEstimating ROM Size DistributionMaximising Sag Mill ThroughputMechanistic Blast Outcome MeasurementMining Automation ProgramModelling the Impact of Rockmass on FragmentationOptimising Development BlastingOptimising Drill & Blast at Olympic DamOptimum BlastingPriming with Multiple Delays with the Same TimingTamping Practices in Development BlastingA Blasters Tool to Measure FragmentationThe Challenge of Precise Measurement of Precision

A Blaster's Tool to Measure Fragmentation

David P. Lilly, P.E., DynoConsult (A Division of Dyno Nobel, Inc.), Pawleys Island, SC, USA

Larry Mirabelli, DynoConsult (A Division of Dyno Nobel, Inc.), Roswell, GA, USA

ABSTRACT

In 1777, the French naturalist, Georges Louis Leclerc, Compte de Buffon developed a statistical technique to estimate the width between two parallel lines by randomly throwing a needle at the two lines and counting the number of times the needle intersected one of the two lines.  By knowing the length of the needle, the distance between the parallel lines could be estimated.  This analysis was named the "Buffon's Needle Problem".

A variation of the "Buffon's Needle Problem" was the "Clean Tile Problem" also formulated by Buffon in 1777.  The "Clean Tile Problem" calculates the number of tiles a thrown coin will cover on a floor that is regularly tiled.  The answer is dependent upon the tile spacing of the tiles and the diameter of the coin.

Using a variation of the "Clean Tile Problem", in the early 80s one of the authors lashed together loading poles into a rectangle and randomly placed them on a muck pile to establish average fragment size.  By counting the number of intersections of the loading poles with the stone edges, a rough measure of average fragment size was obtained.

Some of the more sophisticated methods for measuring the size distributions of microscopic particles such as blood platelets have suggested simpler manual methods to assess fragmentation.  One such method is the "Chord Analysis Method".  The "Chord Analysis Method" uses a loading pole of known length and by counting the number of rock fragments along the pole and using simple geometric calculations, a rough estimate of average fragment size can be calculated.

The "Chord Analysis Method" will be developed and evaluated as a way for blasters to quantitatively assess the degree of fragmentation in a blast.  While there are more precise commercial methods using digitally evaluated photographs, this manual method is a quick method to evaluate blasts when cameras are not available or time constraints don't allow a more precise measurement.  This step in the quantification of fragmentation will complement the increased emphasis within the mining industry to integrate blasting more quantitatively into the mining process.
Downloads