GEOMINING GUIDE FOR CEMENT QUAARY MANAGER 3.7 Designing Surface Blasting Rounds . Table of Contents 1. Health , Safety and Environment 2. Geology 3. Surface 4. Mobile Drilling and Blasting Equipment 5. Crushing and Screening 6. Raw Mix 7. Mine Planning 8. Outsourcing and Contractor Management 9. Performance 10.Cost Management Management GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds 2 Table of Contents 3. Surface Drilling and Blasting 1. Surveying Work in Drilling & Blasting Work 2. Surface Drilling 3. Industrial Explosives 4. Priming Initiation and Blasting Accessories 5. Rock Breakage Mechanisms 6. Blasting Geology 7. Designing Surface Blasting Rounds 8. Rock Fragmentation 9. Environmental Effects of Quarry Blasting 10. Quarry Blast Diagnosis 11. Blast Optimization 12. Specialized Blasting Techniques 13. Misfire Handling 14. Planning of Drilling and Blasting Work GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds 3 Designing Surface Blasting Rounds Rock Geometry Explosives GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds 5 Factors Affecting Blasting Operation Rock Properties Hardness Young modulus Compressive strength Tensile strength Porosity Vibration, Air blast, Fly rock, Rock Fragmentation and Cut according blast design Blast Design Properties Hole diameter Bench height Burden Spacing Stemming length & material Sub-drilling Drill pattern Explosive Properties Types (ANFO, emulsion, gel, dynamite etc.) Velocity of detonation Density, Water resistance Quantity, Delay GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds 6 Optimum Explosives Performance Optimum Explosive Performance May be achieved : Explosive energy distribution in the rock-mass : Energy must be evenly distributed to achieve uniform fragmentation Explosive energy confinement Explosive energy must be confined long enough after detonation to establish fractures and to displace material Use the proper stemming length and stem material type Explosive energy level Energy level must be sufficient to overcome the structural strength and mass of the rock and while providing controlled displacement Determine energy level on the degree of fragmentation and displacement required GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds 7 Geometrical Parameters of Bench Blast Hole Diameter Burden Spacing Bench Height Angle Of Inclination GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds 8 Hole Diameter Factors Controlling Hole Diameter Selection: Safety Environmental effect (vibration, air-blast ,fly-rock and dust) Degree of fragmentation Equipment used Bench height Geological formation The selection of the blast-hole diameter is a key factor in efficient blasting. A rule of thumb is the maximum suggested blast-hole diameter (mm) for a known bench height should be equal to the bench height (m) multiplied by 15. GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds 9 Hole Diameter & Bench Height The selection of the blast-hole diameter is a key factor in efficient blasting. The maximum hole diameter should be H/60 . Smaller holes distribute the explosive energy better than larger holes. Greater hole diameters lead to improper energy distribution. GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds 10 Hole Diameter & Bench Height _ Large hole diameter and low bench energy yield are difficult to control. _ Bad blast effect _ Small hole diameter and high bench energy yield are reduced. _ Drill and blast cost is high GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds 11 Hole Diameter & Burden What is the burden with 102 mm hole diameter? GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds 12 Burden Formulas Burden values 127mm hole diameter GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds 13 Hole Diameter & Burden Optimum Burden is in the range of 20 to 40 times the hole diameter, depending on the rock breakage. Øc = Hole diameter V > 60 Øc V = 60 Øc V = 40 Øc V = 20 Øc GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds 14 Pattern Types equilateral pattern gives most even distribution S:B ratio = 1.15 - good for very hard rock energy fall distance2 @ square centre 23% less GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds 15 Basic Blast Design Typical burden dimensions in the mining and quarrying industries are: average ~ 32 hole diameters in average density rocks (<3.3 g/cc) 26 hole diameters for high density rocks (3.3 g/cc). Burden stiffness ratio (Bench Height / Burden): If ratio <2 , rock-mass will be stiff, harder to fracture and require more subdril. Low stiffness ratios require relatively higher energy factors to produce uniform fragmentation. GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds 16 Basic Blast Design Poor Energy Distribution Bench Height Hole Diameter Burden Stifness Ratio Stemming Vertical Energy Dist. : 10m : 311mm : 10m :1 : 7m : 30 % Bench Height Hole Diameter Burden Stifness Ratio Stemming Vertical Energy Dist. : 10m : 145mm : 5m :2 : 3.5m : 65 % Bench Height Hole Diameter Burden Stifness Ratio Stemming Vertical Energy Dist. : 10m : 92mm : 3.3m :3 : 2.3m : 77 % Fair Energy Distribution Good Energy Distribution The stiffness ratio can be improved by using smaller hole diameter or greater bench height and Vertical Energy Distribution > 80% for uniform fragmentation GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds 17 Burden & Spacing excessive burden reduced fragmentation, displacement small burden rock / face burst, airblast excessive spacing reduced fragmentation, toe / face problems small spacing inter-hole crushing, cratering, blocks, toe GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds 18 Burden & Spacing GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds 19 Basic Blast Design Spacing: normally ranges from 1 to 1.8 times the burden Optimum energy distribution spacing = 1.15 x burden pattern = staggered configuration. Subdrilling: = burden (m) x 0.3 OR = charge diameter (mm) x 0.0085 Stemming Material: crushed stone 4-11mm for Ø<102mm 8-20mm for Ø>102mm GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds 20 Basic Blast Design Stemming: = burden (m) x 0.7 OR = charge diameter (mm) x 0.022 ALSO Stemming should be based on the Relative Confinement (RC) of the explosive charge, not only percentage of the burden dimension RC = (Stem Length x 210 000) + (Charge Diameter x 600) (Charge Energy ABS X Charge Diameter) Charge Energy ABS (Absolute Bulk Strength) for ANFO is 3,145j/cc RC should be greater than 1.4 to prevent excessive loss of confinement and flyrock GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds 21 Hole Inclination Hole inclination, generally 5 to 25 (10 to 15 most common) Disadvantages of inclined holes: Increased alignment errors More difficult to achieve drilling accuracy Closer supervision required, expert driller Shorter bit life and high drilling cost/m Advantages of inclined holes: better energy distribution reduced back break and toe problems, Improved muckpile shape and position, Stable bench edge. GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds 22 Blast Design Select shape and layout of blast to avoid adverse edge effects, fly-rock and air-blast enabling efficient blasting and optimum explosive performance Length to depth ratio to minimize back break, stemming ejection and air blast GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds 23 Blast Shape Select a shape The broken rock needs 30-40 % extra volume for swell Avoid 90° corners Utilize free faces A: Not bad. Some damage to corners. B: Very good shape utilizing to free faces C: Damage to corners. stemming ejection and air-blast D: Damage to corners. High probability for stemming ejection and air blast E: Box-cut = damage, air-blast and fly-rock A B C GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds D E 24 Explosive Energy Effect Hole angle Number of free faces Sub drill Diameter of the hole Stiffness of the bench GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds 25 Stiffness Ratio The stiffness of the bench is the bench height divided by the burden S h V h : Bench height [m] V: Burden [m] Stiffness ratio 1 2 3 4 Fragmentation Bad Medium Good Excellent Air-blast Bad Medium Good Excellent Fly-rock Bad Medium Good Excellent Vibrations Bad Medium Good Excellent Comments BAD DESIGN New design if possible GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds Increasing the stiffness-ratio above 4 does not always give a positive effect 26 Timing Purposes of sequential detonation are to : Control the application of explosive energy during the detonation of the blast Control explosive energy confinement Maintain maximum explosive energy input Delay: between holes in a row should be in the range of 3 – 10 ms/m of Spacing between holes rows should be in the range of 10 – 30 ms/m of Burden GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds 27 Timing and Muck Pile Profile materials thrown back onto bench excessive backbreak especially with high benches tight some overbreak with high benches tight, compact little overbreak loose, spread out GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds Insufficient interval between rows ( less than 6 ms/m of burden ) Short delay interval between rows ( 6 to 12 ms/m of burden ) suitable for shovel excavation Long delay interval between rows ( 12 to 30 ms/m of burden ) suitable for loader excavation or blast casting 28 Delay Between Rows GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds 29 Delay Between Rows The proper delay between rows depends on: 42 ms No of rows 67 ms Equipment Previous blast mucked out Charge concentration Rock proporties GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds 30 Straight Firing Pattern GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds 31 Straight Firing Pattern (Nonel) GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds 32 V Shape 1 Firing Pattern GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds 33 V Shape 1 Firing Pattern (Nonel) GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds 34 V Shape 2 Firing Pattern GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds 35 V Shape 2 Firing Pattern (Nonel) GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds 36 Firing Pattern (Nonel) GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds 37 Comparing Firing Pattern GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds 38 Directed Firing Pattern (Nonel) GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds 39 Directed Firing Pattern GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds 40 Blasting Software Task Software Features 1. Hole layout Mine design system Survey, Geology 2. Charging MDS, in-house Geology 3. Timing Compu-Blast ShotPlan Vib. analysis Plans, simulation 4. Specialist ProWall, ProBlast Costing 5. General PBS JKSimBlast Very basic Comprehensive 6. Other WinProf Flexit Face profile Hole deviation GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds 41 Group Exercise Suggest a loading pattern for the example below Parameters: Crest Face height 15.0 metres Hole inclination = 80° Stemming Hole diameter = 110mm B (4.0 metres) Blast hole depth = 16.5 metres Burden (B) = 4.0 metres Spacing (S) = 4.0 metres Sub-grade (U) = 1.3 metres Hole Quarry Face (15m) ANFO Column Charge ANFO (9kg/metre) (12.5 metres) Cast Pentolite primer (112.5 kgs) Nonel Unidet 500 Toe Pentolite Primer Explosives available: U Quarry Floor (454 g) with 1 x U500 Detonators GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds 42 Group Exercise Suggest a loading pattern for the example below Parameters: Crest Stemming Face height 12.0 metres Hole inclination = 75° Hole diameter = 105mm B (3.2 metres) Blast hole depth = 13.4 metres Burden (B) = 3.2 metres Spacing (S) = 3.2 metres Sub-grade (U) = 1.0 metres ANFO Column Charge (7.2 metres) Hole Quarry Face (15m) Explosives available: ANFO (9kg/metre) (64.8 kgs) Slurry (12kg/metre) Emulsion (11kg/metre) Cast Pentolite primer Slurry Cartridges Nonel Unidet 500 with 1 x U500 Detonator Water level Toe U Quarry Floor (1.0 metre) GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds 43 Group Exercise Suggest a loading pattern for the example below What are the issues ? A Reduced crest burden (A) Crest Back-break causing reduced burden (B) “Fly-rock risk” Quarry Face B Toe Quarry Floor GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds 44 Group Exercise Suggest a loading pattern for the example below What are the issues ? A Reduced crest burden (A) Crest Bach-break causing reduced burden (B) Increased Stemming “Fly-rock risk” (4.5 metres) Upper Column (explosives) Deck (intermediate stemming) Quarry Face Deck = length of problem area plus 0.3 x Burden (above and below) B (4.0 metres) Lower Column (explosives) Toe GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds Quarry Floor 45 Group Exercise Suggest a loading pattern for the example below What is the issue ? Crest Reduced toe burden (C) “Fly-rock risk” Quarry Face C Toe GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds Quarry Floor 46 Group Exercise Suggest a loading pattern for the example below What is the issue ? Crest Reduced toe burden (C) “Fly-rock risk” Stemming (4.0 metres) Quarry Face Confinement at toe must be increased to eliminate fly-rock Explosives Column (with Primers and Detonators) C Toe GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds Quarry Floor 47 Effects Due To Bad Design Loading Hauling bad truck filling bunching due to boulder selection Crushing low bucket fill factor boulder selection lower diggability bad under-footing of loading area higher maintenance cost for loading equipment higher kWh/t higher maintenance cost for crusher Secondary breakage more work and more cost GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds 48 Problem Solving Toes and irregular floor Increase subdrilling Reduce drilling pattern Increase bottom charge Increase delay times between rows Boulders Reduce drilling pattern Use higher strength explosive Increase charge in the hole Redistribute the charge in the hole Adjust delay times between holes Fines Increase drilling pattern Use low strength explosive Decrease charge in the hole Redistribute the charge in the hole GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds 49 Problems Solving (Continued) Fly rock Control burden in front row Control voides or cavities in the holes Control hole deviation Adjust delay times between holes Adjust stemming length and material size Vibration Reduce charge weight per hole or delay Reduce number of holes with the same delay Adjust delay time and firing sequence Control geometric design of blast Make face with large free area Air blast Adjust stemming length and material type Use electrical initiation and decrease use of detonating cord Cover detonating cord when it is used Decrease charge hole Adjust delay times between holes GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds 50 Problems Solving (Continued) Reduced displacement and swelling Increase powder factor Reduce burden in first row Adjust delay time and firing sequence between holes and rows Increase bottom charge Backbreak Reduce charge in holes of last row Reduce number of rows Reduce burden size Adjust delay times between rows Adjust stemming length and material size Misfires Check circuit resistance Check connections Check geological discontinuities Adjust delay times GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds 51 Thank You GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds 52