Effect of blast preconditioning on comminution for selected rock types
- Univ. of Utah, Salt Lake City, UT (United States). Mining Engineering
Current research in comminution includes efforts to increase the efficiency of mineral processing systems and reduce the amount of electrical energy needed for size reduction. In most mining operations, comminution begins with blasting. Normally, blast design focuses on loosening material for excavation and sizing the product for efficient haulage. It is likely that blasting also results in internal damage to rock fragments within the blast pattern which may provide subsequent comminution benefits. Quantitative assessment of comminution benefits under field conditions is complicated by highly variable geological factors and the difficulty of reducing large tonnages of blasted material to representative samples. For these reasons, laboratory experiments were conducted to explore potential blast preconditioning benefits. To achieve high stress levels and to include the effect of direct coupling of the explosive with the rock, blocks of rock were fragmented using charged drillholes. Samples representing the undamaged and blast-preconditioned states were tested using the Ultrafast Load Cell (UFLC) developed by the Generic Mineral Technology Center for Comminution at the University of Utah. This device allows measurement of mass specific fracture energy (MSFE) for single particle communition. MSFE is a quantitative and reproducible indicator of energy required for comminution. UFLC measurements indicate varying amenability to blast preconditioning for seven materials selected to represent a range of rock compositions and textures. For the rock types and conditions considered in this series of experiments, the effect of blast preconditioning ranges from no measurable benefit to a reduction of about 40% in average MSFE.
- OSTI ID:
- 398378
- Report Number(s):
- CONF-960234--
- Country of Publication:
- United States
- Language:
- English
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