AN ENERGY – FRAGMENTATION APPROACH FOR BLASTING PERFORMANCE

• Author / Creator

  Barreto Maya, Martha Maria

• Blasting is widely used in mining operations as the primary comminution process to reduce the in-situ rock into fragmented material suitable for the subsequent transport and processing. The energy used is released from an explosive by detonation and transferred to the rock mass via a shock front resulting from the initial high pressure of detonation and continuing gas expansion pressure from the products of the explosion. Both play an essential role in fracture development.
  This research was focused on creating a practical methodology to measure not only the explosive energy in terms of “specific energy or pressure” and estimate how much of it is used for actual fragmentation, but also to create an easy to use tool to identify and develop optimization strategies for a bench blast in mines and quarries.
  To accomplish this, four stages were developed: a) Explosive characterization in terms of initial detonation pressure and subsequent gas expansion pressure generated, b) Fragment size distribution determination using an Image Analysis System, specifically WipFrag software, c) Rock tensile strength estimation using not only the widely recognized Brazilian Test, but also Digital Image Correlation (DIC) system, and d) a semi-empirical approach for pressure expenditure estimation at three radii from the center of the hole, representing the maximum zone affected by the blast, the outer limit of the crushing zone, and the area midway between borehole wall and maximum zone.
  It was observed that both the initial high detonation pressure and the subsequent gas pressure are essential for the tensile crack initiation and propagation, even though the methodology is not capable of estimating how much of each type of energy is used to create the resulting rock size distribution. For a daily blasting assessment, the technique is easy to follow and only a few variables are needed for it’s implementation.

• Subjects / Keywords

  • Blasting
  • Mining
  • Optimization strategies
  • Efficiency

• Graduation date

  Spring 2020

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-zmz9-w847

• License

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