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Effects of detonator strength on the initiation of small diameter emulsion explosives
177A 923299
Low sheck energy emulsion based wet hole exl~lesives Armstrong, L W; Moxon, N T Proc 3rd lmermUimml Symposimn on Rook FragmetUatioR by Blasting, Brisba~, 26-31 Aag 1990 P45-53. Pubi Purkville: AuslMM, 1990 A series of low shock energy ANFO-based explosives has been developed for use in weak overburden or where reduced damage outside the blast zone is desirable. Handling, water resistance, and explosive properties have been examined as functions of emulsion base, additive used, density, and charge diameter. The use of one such explosive at the Cadjebut zinc mine in Australia is described. Performance at 3 densities was monitored using continuous and point-to-point VOD methods. Cost savings are possible when compared to currently used packaged emulsion explosives. 9233OO Experimental study of the effects of shock and gas penetration
in bhu~g Brinkmann, J R Pro¢ 3rd lmermlffmmi Symposimn on Rook FragmentatioR by Blasting, Brisba~, 26-31 Aug 1990 P55-66. Publ Parkville: AuslMM, 1990 Different explosives used in South African gold mines provide pronounced breakage differences. To identify the mechanisms responsible, several aspects of explosive-rock interaction were investigated. A blasthole liner method was developed which allows separation of breakage effects due to shock and gas penetration. Different explosives behave in distinct manners in small diameter blastholes, due to different reaction rates and energy partition between shock energy and heave energy. Results are discussed for watergel, ANFO, emulsion, and dynamite explosives. 923301
Characteristics of propagation process of detonation in charge under influence of channel effect Lin Deyu; Li Zhixing; Wang Minglin Proo 3rd Imermatiomal Symposhun on Rook Fragment&ion by Blastiag, Brisbane, 26-31 Aug 1990 P67-68. Pubi Parkville: AusIMM, 1990 Detonation is often stopped in underground blasting due to the channel effect, especially for holes long in relation to diameter. The radial gap between charge and blasthole wall is a primary factor in the channel effect. Scale model tests were carried out to examine the variation of detonation velocity along an explosive charge. Due to the channel effect, the charge does not explode fully and distance of detonation is about 60% of charge length. Energy distribution along the charge under these conditions is analysed. A two-point bidirectional initiation regime is proposed to minimise the channel effect, and in-mine data for its use presented. 923302
Effect of detonator strength on the initiation of small diameter emulsion explmives Kennedy, D L; Kennedy, M; Kerr, I D Proo grd imerutiomal Sympmhun oR Rock Fragmemafom by Blasting, Brisbaoo, 26-31 Aag 1990 1'69-77. Publ Parkville: AuslMM, 1990 Model tests were carried out using small diameter charges of emulsion explosives initiated by detonators of two strengths. The shape and position of the shock waves were monitored by flash X-radiographs at different times after fuse head operation. Finite element simulations using the code DYNA2D agreed well with experimental data. In both cases initiation of
the: emulsion was primarily forward from the detonator, but Lhe .~hock~aves were delivered differently for the different detonators. Practical consequences are discussed.
Machine excavation 923303
Brittleness and micro-scale reck cutting efficiency Goktan, R M Min Sci Teclmol V13, N3, Dec 1991, P237-241 An attempt is presented to improve understanding of the relations between brittleness and cutting efficiency of chisel picks on the basis of published experimental data. Rock brittleness is here defined in terms of compressive and tensile strength of the rock. Correlations between brittleness and specific energy values for coals and coal measures rocks are examined, but no reliable relation between the two parameters is found. The adoption of a single brittleness parameter, in place of a concept relevant to rock excavation, may not be correct. 9233O4 Comparison of longitudinal and transverse cutting heads on a dynamic and kinematic basis Hekimoglu, O Z Min Sci Teclmoi V13, N3, Dec 1991, P243-255 There have been many claims about the merits of longitudinal (spiral) or transverse (drum) types of roadheader cutting heads. Dynamic and kinematic analyses of both types under the same operational and design conditions are presented. Results are compared to long term field trial data for longitudinal cutting heads. Head design has a significant influence on performance of both head types. Resultant boom forces tend to act perpendicular or parallel to the boom axis of longitudinal and transverse heads respectively. For transverse heads the boom reaction is large during transition from arcing to lifting, and arcing provides a more consistent product size. 923305 Theoretical and practical aspects of circumferential pick spacing on boom tunnelling machine cutting heads Hekimoglu, O Z; Fowell, R J Min Sci Teclmol V13, N3, Dec 1991, 1'257-270 The effects of equally spaced circumferential pick spacing on performance of roadheader cutting heads have been examined using laboratory and in situ trials. This spacing is an important parameter affecting cutting head balance and is limited by total number of arcing picks and tool lacing. Alternate lacing patterns are compared in terms of cutting efficiency and manufacturing feasibility. Using commercially available tool holders, up to 27 heavy duty picks can be laced at equal spacing on a medium duty cutting head. Tool holder overlap problems may be reduced by using a threestart arrangement employing a higher angle of wrap, but this may also lower cutting efficiency. 923306
Material diggnbility studies for the assessment of bucket wheel excavator performance Bolokbasi, N; Koncagul, O; Pasamehmetoglu, A G Min Sci Teeluml V13, N3, Dec 1991, P271-277 BWE diggability is often estimated on the basis of results from the Orienstein and Koppel wedge test. This test requires specimens of fixed geometry and size which are difficult to obtain and prepare. To overcome this problem, O and K wedge tests results have been compared to specific cutting energies from the standard cutting test, and good correlation found. The
© 1992 Pergamon Press Ltd. Reproduction not permitted RMMS 29/3--L
Low sheck energy emulsion based wet hole exl~lesives Armstrong, L W; Moxon, N T Proc 3rd lmermUimml Symposimn on Rook FragmetUatioR by Blasting, Brisba~, 26-31 Aag 1990 P45-53. Pubi Purkville: AuslMM, 1990 A series of low shock energy ANFO-based explosives has been developed for use in weak overburden or where reduced damage outside the blast zone is desirable. Handling, water resistance, and explosive properties have been examined as functions of emulsion base, additive used, density, and charge diameter. The use of one such explosive at the Cadjebut zinc mine in Australia is described. Performance at 3 densities was monitored using continuous and point-to-point VOD methods. Cost savings are possible when compared to currently used packaged emulsion explosives. 9233OO Experimental study of the effects of shock and gas penetration
in bhu~g Brinkmann, J R Pro¢ 3rd lmermlffmmi Symposimn on Rook FragmentatioR by Blasting, Brisba~, 26-31 Aug 1990 P55-66. Publ Parkville: AuslMM, 1990 Different explosives used in South African gold mines provide pronounced breakage differences. To identify the mechanisms responsible, several aspects of explosive-rock interaction were investigated. A blasthole liner method was developed which allows separation of breakage effects due to shock and gas penetration. Different explosives behave in distinct manners in small diameter blastholes, due to different reaction rates and energy partition between shock energy and heave energy. Results are discussed for watergel, ANFO, emulsion, and dynamite explosives. 923301
Characteristics of propagation process of detonation in charge under influence of channel effect Lin Deyu; Li Zhixing; Wang Minglin Proo 3rd Imermatiomal Symposhun on Rook Fragment&ion by Blastiag, Brisbane, 26-31 Aug 1990 P67-68. Pubi Parkville: AusIMM, 1990 Detonation is often stopped in underground blasting due to the channel effect, especially for holes long in relation to diameter. The radial gap between charge and blasthole wall is a primary factor in the channel effect. Scale model tests were carried out to examine the variation of detonation velocity along an explosive charge. Due to the channel effect, the charge does not explode fully and distance of detonation is about 60% of charge length. Energy distribution along the charge under these conditions is analysed. A two-point bidirectional initiation regime is proposed to minimise the channel effect, and in-mine data for its use presented. 923302
Effect of detonator strength on the initiation of small diameter emulsion explmives Kennedy, D L; Kennedy, M; Kerr, I D Proo grd imerutiomal Sympmhun oR Rock Fragmemafom by Blasting, Brisbaoo, 26-31 Aag 1990 1'69-77. Publ Parkville: AuslMM, 1990 Model tests were carried out using small diameter charges of emulsion explosives initiated by detonators of two strengths. The shape and position of the shock waves were monitored by flash X-radiographs at different times after fuse head operation. Finite element simulations using the code DYNA2D agreed well with experimental data. In both cases initiation of
the: emulsion was primarily forward from the detonator, but Lhe .~hock~aves were delivered differently for the different detonators. Practical consequences are discussed.
Machine excavation 923303
Brittleness and micro-scale reck cutting efficiency Goktan, R M Min Sci Teclmol V13, N3, Dec 1991, P237-241 An attempt is presented to improve understanding of the relations between brittleness and cutting efficiency of chisel picks on the basis of published experimental data. Rock brittleness is here defined in terms of compressive and tensile strength of the rock. Correlations between brittleness and specific energy values for coals and coal measures rocks are examined, but no reliable relation between the two parameters is found. The adoption of a single brittleness parameter, in place of a concept relevant to rock excavation, may not be correct. 9233O4 Comparison of longitudinal and transverse cutting heads on a dynamic and kinematic basis Hekimoglu, O Z Min Sci Teclmoi V13, N3, Dec 1991, P243-255 There have been many claims about the merits of longitudinal (spiral) or transverse (drum) types of roadheader cutting heads. Dynamic and kinematic analyses of both types under the same operational and design conditions are presented. Results are compared to long term field trial data for longitudinal cutting heads. Head design has a significant influence on performance of both head types. Resultant boom forces tend to act perpendicular or parallel to the boom axis of longitudinal and transverse heads respectively. For transverse heads the boom reaction is large during transition from arcing to lifting, and arcing provides a more consistent product size. 923305 Theoretical and practical aspects of circumferential pick spacing on boom tunnelling machine cutting heads Hekimoglu, O Z; Fowell, R J Min Sci Teclmol V13, N3, Dec 1991, 1'257-270 The effects of equally spaced circumferential pick spacing on performance of roadheader cutting heads have been examined using laboratory and in situ trials. This spacing is an important parameter affecting cutting head balance and is limited by total number of arcing picks and tool lacing. Alternate lacing patterns are compared in terms of cutting efficiency and manufacturing feasibility. Using commercially available tool holders, up to 27 heavy duty picks can be laced at equal spacing on a medium duty cutting head. Tool holder overlap problems may be reduced by using a threestart arrangement employing a higher angle of wrap, but this may also lower cutting efficiency. 923306
Material diggnbility studies for the assessment of bucket wheel excavator performance Bolokbasi, N; Koncagul, O; Pasamehmetoglu, A G Min Sci Teeluml V13, N3, Dec 1991, P271-277 BWE diggability is often estimated on the basis of results from the Orienstein and Koppel wedge test. This test requires specimens of fixed geometry and size which are difficult to obtain and prepare. To overcome this problem, O and K wedge tests results have been compared to specific cutting energies from the standard cutting test, and good correlation found. The
© 1992 Pergamon Press Ltd. Reproduction not permitted RMMS 29/3--L