Effects of specific charge and EDD:s on fragmentation in an aggregate quarry, building KCO design curves

Transcription

1 University of Cambridge, Applied Detonation Physics and Blast Modelling, Sept 2014 Effects of specific charge and EDD:s on fragmentation in an aggregate quarry, building KCO design curves Finn Ouchterlony, Montanuniversität Leoben, Austria Ulf Nyberg, Swebrec at Luleå Univ Techn, Sweden. Mats Olsson, EDZ-consulting, Älvsjö, Sweden Kerstin Widenberg, NCC Construction, Solna, Sweden Per Svedensten, Sandvik Construction, Svedala, Sweden.

2 Building KCO design curves 2 Contents Purpose and consortium Test site Tests and data monitoring Fragmentation Blast design curves Conclusions

3 Building KCO design curves 3 Purpose: to validate earlier work with design curves in Vändle granite quarry in a quarry with different geological conditions to evaluate EDD:s (electronic delay detonators) with respect to possible finer fragmentation and other improvements in bench blasting Consortium: MinBaS Mineral Ballast Sten

4 Test site Långåsen quarry at Arlanda airport: 0.4 Mton/yr granodiorite aggregate, test period asphalt plant crusher plant test piles rounds Atlas SmartRig D9C Svedala Arbrå R jaw cr.

5 Tests and data monitoring 5 Round 1-N 0,8 kg/m 3 1-H Nonel 1,1 kg/m 3 row 1: 3,4x3,4 m 2 holes / 25 ms in-row row 2-4: 2,6x3,4 m 67 ms inter-row Round 2-H 1,1 kg/m 3 2-N Nonel 0,8 kg/m 3 row 1: 2,9x2,9 m 2 holes / 25 ms in-row row 2-4: 2,2x2,9 m 67 ms inter-row Round 3 EPD/elektronic 0,8 kg/m 3 row 1: 3,4x3,4 m 10 ms inter-hole in row row 2-4: 2,6x3,4 m 67 ms inter-row Round 4 EPD/elektronic 0,8 kg/m 3 row 1: 3,4x3,4 m 5 ms inter-hole in row row 2-4: 2,6x3,4 m 67 ms inter-row round 1, Nonel 0,8+1,1 kg/m 3 1-N: 7700 m H: 5600 m 3 round 4, elektronics 0,8 kg/m m 3

6 Tests and data monitoring 6 Joint mapping & bench geometry with Blast Metrix Drill collaring & MWD with Atlas Copco D9C Smart rig Hole deviations with Devibench Charging follow up on hole by hole basis VOD, filming, PPV and air blast during rounds Fragmentation from sieving and image based method Building test piles during digging; sorting and crushing Special tests on pile material: LA-abrasion, ball mill, Split Hopkinson bar etc.

7 Tests and data monitoring 7 Rd 1, Nonel, normal (1-N) & high (1-H) specific charge fine to medium grained granodiorite (1-3 mm) UCS = 206 MPa pegmatite dikes major joints strike N20-70 E and dip steeply towards SE

8 Fragmentation 8 Test piles: shuffled, homogenized test piles before homogenization 11 test piles: Pile 1A Pile 2A Pile 1B Pile 2B Pile 3B 3C 3A pegmatite Pile 4D 4C 4D 4A pegmatite 100 ton sieved, fractions weighed, put back, reshuffled before pile run through crusher. variations within EDD rounds of interest

9 Fragmentation t bucket test pile 400 ton bucket Putting back sorted material in test pile reshuffling tray grizzly 200 mm bucket sieve 125 mm truck bucket sieve mm tray 0/40 lab sample +200 lab -sample tray bucket +125 interim storage 0/125 mm 40/75 75/125 Grizzly +200 mm weighed, put back -200 weighed, sieved Sorting mm weighed, put back -125 weighed, to interim storage, then sieved Sorting mm weighed 40/75 mm weighed -40 mm weighed Weighing: Bucket scale, product scale, belt scale, belt motor power

10 Fragmentation 10 Median fragment size from sieving, x 50 for ave. loss scenario EDD initiation: coarser fragmentation than Nonel at normal specific charge! conclusions supported by image analysis pegmatite Nonel: a higher specific charge gives finer fragmentation X

11 Blast design curves Lab sieving test piles mtrl before (sorted) and after crushing: 11 useful data range 45 Each curve average of 11 samples, one for each pile Curves renormalized with respect to total weight of 0/16 mm fraction of 0/125 mm samples. Agreement between curves good in 0/16 mm range 0/45 mm part of 0/125 mm curve represents muck pile fines

12 fines region from lab samples, 0/45 out of 0/125 middle region from test pile sieving fines tail spliced to test pile data use Swebrec function consider equiv. grizzly opening coarse region from estimating boulders Blast design curves Building complete sieving curves: lab sieving boulder part test piles overlap mm boulders 12

13 Blast design curves 13 P pile (x) P round (x) Difference between pile and round (pile + oversize OS) affects x 50 and whole curve Fragmentation distribution for loaded test pile, excl. OS% P pile (x) = P round (x)/[1-os/100] for x x OS Swebrec function for whole blast round, incl. oversize OS P round (x) = P (x) = 100/{1+[ln(x max /x)/ln(x max /x 50 )] b } Five parameters to determine; x 50, x max, b + OS and x OS

14 Blast design curves: Finding P round 14 Stepwise procedure to find x 50, x max, b, OS and x OS. Use r 2, x max, b and residual OS to judge fits See how closely Swebrec P(x) describes pile data Reweight influence of residuals, w=1, OS still 0% Equiv. grizzly mesh (//200 #220 mm), reweight 1/x OS = 5% for rounds data. x OS = m For high q rounds OS = 4%, for low q, OS = 7% Use same b = 4,17 or blasting harder creates less -1 mm fines r 2 = 0,998, x max = 5-10 m, OS res = 1-2%, b = 0

15 Residuals [5] Långåsen q = 0,99, OS=4%, #220 mm, x OS =1000 mm, w=1/x^0,25 r 2 = DF Adj r 2 = FitStdErr= Fstat= a= b= Andel passerar, % Mass passing, % Blast design curves P pile (x) Maskvidd, mm Mesh size, mm Best case results entered into Kuz-Ram model s x 50 eqn: Fitting case: Round Round q Q s ANFO x 50round A 0,8 A 0,84 parts kg/m 3 kg/hole % mm - - F1: Nonel normal q 1-N + 2-N 0,722 96,7 0, ,5 4,69 4,63 F2: Nonel high q 1-H + 2-H 0,992 91,6 0, ,4 4,48 4,48 C3: EDD normal q , ,1 0, ,3 6,11 6,05 10

16 Blast design curves 16 Recalculated 100% level with 4 and 7% OS of Nonel rounds x 50 = 10A Q 1/6 (115/s ANFO ) 19/30 /q 0,84 in mm Q kg expl. per hole s ANFO % weight strength rel. ANFO, q kg/m 3 specific charge. A = 0,039 (RMD+RDI+HF), 0,039 best choice for Långåsen instead of Kuz-Ram value 0,06. A = 4,56 for Nonel rounds. P round (x) = 100/{1+[ln(x max /x)/ln(x max /x 50 )] b } gives sieving curves if b = 4,17 and x max = f(b, x 50, B och S/B) from eqns. s 50 x 50round 0,75 = 0,2 (0,0415/B) 0,25 where slope s 50 at x 50 s 50 = b/[4x 50round ln(x max /x 50 )] for Swebrec function Kuz-Ram (2005) predicts finer fragmentation (delay effect) and steeper curve (scatter) for EDD but the reverse is true. EDD rounds can not be included in design formulas

17 Blast design curves: Nonel 17 Design curves for other conditions may be calculated from KCO formulas. region with lower accuracy as boulder part exaggerated

18 Conclusions Use of a higher specific charge in the Nonel rounds; 0,99 instead of 0,72 kg/m 3, had the effect of: a much finer x 50, down from about 160 to 120 mm Using EDD instead of Nonel initiation, at roughly normal specific charge had the effect of: a much coarser x 50, up from about 160 to 200 mm The fragmentation of the EDD initiated rounds doesn t follow the Nonel design curves. Kuz-Ram prediction eqn for x 50 appears to work well with minor calibrations of rock mass factor A, C(A) = A /A = 0,039/0,06 0,65 for Nonel rounds C(A) 1,0 for EDD rounds means a timing effect 18

19 Conclusions 19 Previous Vändle design curves apply, with small changes, also to the Nonel rounds at Långåsen Project goals met Tested prediction equations for x max and b are missing though. Here a use of oversize estimates OS = 4-7% allowed fixing a constant b-value for the Nonel rounds. Then an experimental connection between x max and x 50 and b gave reasonable estimates of x max. The final Swebrec report (Ouchterlony et al. 2010) contains much more data.

20 Input data for design curves: Blast design curves Granodiorite Bench height H, m 16,0 Density, kg/m Joints: vertical + Subdrilln. UB, m 1,5 Charge Q, kg/m 6,4 dipping from face Hole dip, º 11,2 Charge Q, kg/hole 103 Density, kg/m Uncharged OL, m 1,7 First row S/B 1,0 UCS, MPa 206 Charge length L, m 16,1 - rows 2-4 S/B 1,3 P-wave, m/s Hole diameter, mm 86 No. of rows 4 B S S/B V b q x 50 +1,0 m -32 mm m m - m 3 /hole kg/m 3 mm % % 2,0 2,6 1,30 89,4 1, ,4 25,8 2,1 2,7 1,29 97,2 1, ,0 24,7 2,2 2,9 1,32 110,2 0, ,7 23,0 2,3 3,0 1,30 118,8 0, ,3 22,1 2,4 3,1 1,29 127,7 0, ,9 21,2 2,5 3,3 1,32 142,6 0, ,8 19,9 2,6 3,4 1,31 152,3 0, ,4 19,1 2,7 3,5 1,30 162,4 0, ,1 18,5 2,8 3,6 1,29 172,8 0, ,8 17,8