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_ ____ _ <br />sa..m.w.w.ed Al... dew cnrw....9nr ..Yw m .elw <br />cr ~ ~ r~ <br />f '' <br />1 } I ~ saw ~.v...w e.ti.... irn.:i..nwn ~bucwl .r <br />Q M.w se.wo.rd !Tr ng1.1 ..~.w q .wMOR.d <br />pwdlr .ww.l. nn.:., eew.ww.i.. .s.m pw~..w <br />'~ ~ .. 'l al.w i..d..aed <sewwrw nr.m I.e.w <br />' ~ G.d.d...leynw.rv..dwm/le..m. pre-Split Crack Formation <br />el !/m ~.ar..e~ n..m <br />~' Fast estimates of smooth blasting and pre-splitting layouts and explosive charge weights can be gained <br />from Table L <br />~' Table 1-Recommended Dimensions for Smooth-Wall and Pre-Split Blastine. <br />.' DriIlhole Charge Fxplosive• <br />diameter diameter Spadag Burden Sparing" <br />mm m mm is kg/m Ib/ft m ft m ft m ft <br />' 30 L?5 ll OS 0.07 0.05 OS L6 0.7 Li 0^5-03 0.8-LO <br />37 1S 17 0.6.3 O.L 0.08 0.6 ZO 0.0 3.0 030-0.5 1.0-1.6 <br />44 L75 17 0.63 0.17 011 0.6 20 09 3.0 030-0.5 1.0-L6 <br />51 20 ^? 0.98 0~5 0.17 0.9 25 Ll 3.6 0.45-0.75 1 ~ ? <br />62 2.38 2'' 0.88 035 0?; 1.0 33 li 41 OSS-0.8 1.8 25 <br />75 3.0 ?5 LO 0:0 034 11 4.0 L6 5? 0.60-0.9 2.0-3.0 <br />' , 87 3S S LO 0.70 0.47 LS 4.6 L9 61 0.70-L] 23-33 <br />100 4.0 ?9 L] i 090 0.60 L6 51 ? 1 6.9 0.90-L'_ 26-1.0 <br />125 5.0 40 L63 Ld0 094 20 6.6 27 8.9 L00-La 33-».9 <br />' L50 6.0 50 20 200 L34 24 79 31 lOS L20-L3 4.05.9 <br />200 8.0 52 20 3.00 202 3.0 9.8 4.0 13.0 LO 2:1 4.9-6.9 <br />ZO 10.0 6~ ? S 3~8 Z^7 3.4 ].L= 4S 14.$ LSO-2 i 59-7.9 <br />~, • Baud on Nitro Nibel's Dynamex B Explosive <br />''Burden is assumed to be infinite since the pre-split charge is fired before the main cdtarge. <br />,' SMOOTH WALL BIASTLYG PRESPLIT BLASTING <br />Production Blast Control <br />!, a) Delay Interval <br />In mold-row blasting, unless the imerval between delays u suffidem to allow the rock ahead of a row <br />' to move and to swell thrn that row is overloaded by the row is from. Therefore the following can <br />occur iF the delay interval is too short <br />;, o poor fragmentation <br />o severe backbreak and flyrock <br />o toe problems and only partial breakage of final row <br />' o tight and high muckpile <br />1 <br />t <br />