New method to test the rock breaking properties of explosives in full scale
Titel:
New method to test the rock breaking properties of explosives in full scale
Auteur:
Rustan, A. Nie, S. L.
Verschenen in:
International journal of mining, reclamation and environment
Paginering:
Jaargang 6 (1992) nr. 4 pagina's 191-200
Jaar:
1992
Inhoud:
During our research it was found that, still today, the rock breaking properties of an explosive can not be accurately determined by laboratory test or theoretical calculations. The new test method proposed here for bench blasting is based on single hole blasts in model- and full scale with different burdens up to and greater than the critical burden. The tests in full scale should be done with that hole diameter, length of hole, explosive and stemming etc., desired to be used in the real operation. The new method includes determination of the fragment size distribution, the backbreak, the throw, the centre of gravity change and the damage to the remaining rock for each burden tested. This will yield the maximum information possible for understanding how the explosive interacts with the rock. The field tests to examine the single hole blasts were done at Storugns limestone quarry on Gotland, and the model blast tests at Luleå University of Technology They showed that there exist a good correlation between the model- and full scale tests regarding the angle of breakage versus burden and the relation of k50 versus burden, where the function has the same shape, and finally the power for the specific charge is the same both in the model- and full scale. Critical burden and fragmentation gradient are well correlated with the impedance of the rock in the model tests. It seems that the model test can reveal many of the rock breaking properties of an explosive in full scale. The test procedure used for the model and full scale test were therefore proposed as a first idea to an international standard. Based on the systematic investigation carried out at Storugns limestone quarry it was theoretically possible to increase the profit up to 8 million SEK/year by changing burden and spacing and thereby reducing the amount of fines (>25 mm), which is treated as waste in the quarry.
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