Drilling methods and commonly used machinery

Transcription

1 Drilling methods and commonly used machinery worked out and giving a lecture by Jouko Salonen Sandvik Mining and Construction Oy

2 Competencies required in Drilling. Straight-hole drilling and drill patterns: The shotfirer must be familiar with various drilling methods and related machinery and equipment. He/she must be able to inform the driller about preferences as to drill pattern, depth, inclination of holes and matters like health and environmental issues. The shotfirer must understand the importance of straight-hole drilling and drilling errors, the position of the hole, direction and depth. Straight-hole drilling is of paramount importance while doing bench blasting, demolition work and tunnelling. Tools for straight-hole drilling: Right drill rig. Proper drill steel. Accurate drilling of patterns. Inclination, deviation and depth measurements. Safety when drilling, dust evacuation and noise reduction.

3 List of contents: 1. Drilling machinery, hydraulic/pneumatic/others 2. Drilling methods 3. Drill steels 4. Communication between shotfirer and driller 5. The importance of precise drilling, the position of the hole, the direction and the depth 6. Drilling for demolition 7. Occupational health and safety Amount of slides in this workpackage: Total material (WP2) includes 107 slides. Fundamental knowledge Supplementary knowledge Danger In this presentation 23 examples of them are shown.

4 Training plan Contents Time 5 hours 1 Drilling machinery 30 min 2 Drilling methods 30 min 3 Drill steel 30 min 4 Communication between shotfirer and driller 15 min 5 Importance of precise drilling 150 min 6 Drilling for demolition 7 Occupational health and safety 15 min 30 min

5 1. Drilling machinery. Hydraulic/pneumatic/others. Hand held drills + compressors and hydraulic power unit, petrol driven drills Rigs of different sizes (and types) Underwater drilling Tunneling and UG mining drilling equipment

6 Typical hand held drilling machinery: A hand held drill, usually pneumatic. Dust collector, usually pneumatic. Compressor as a power unit for the drill and the dust collector. All these can be hydraulic ones as well. For very small tasks it is sometimes economical to choose a petrol driven drill.

7 Underwater drilling Top hammer drilling unit on board

8 Rotary drills Rotary rigs are only used in large scale production like surface mining.

9 Tunneling and UG mining drilling equipment

10 Drilling methods: Top Hammer DTH Rotary F F F Hammer on top Hammer in the hole No hammer at all

11 Criteria for selecting drills: rock conditions (hardness, homogenous), tramming conditions environmental requirements annual production (m 3 or t) => number of drills critical diameter of explosive => hole size big enough? flexibility in usage => different types of work? application costing => D&B costs per m 3 or t level of automation operator comfort and safety ease of between site/pit transport operator startup training Productivity Training before startup Machine delivery Contractor benefit Training during startup Time Drilling simulator in use A rig simulator can be very useful for un-experienced operators.

12 3. Drill steels: shank, rods, tubes, different bits Top hammer Down the hole Rotary

13 Drill steel, TH:

14 Straight-hole drilling Select a drill bit that gives best drilling accuracy in current rock conditions Flat face Normal skirt Drop Center Normal skirt Flat face Retrac Drop Center Retrac Guide Bit Deviation estimate (64 mm, h=15 m): 1.05 m 1.0 m 0.7 m 0.4 m 0.3 m

15 4. Communication between shotfirer and driller Drilling data from shotfirer (or blasting manager) to driller: drill pattern, hole size, depth, sub drilling, inclination of the holes, accuracy level. Information from driller to shotfirer according to observations during drilling (e.g. MWD). Measuring drill hole position and path. One must re-do the blast design after getting information from driller.

16 5. The importance of precise drilling, the position of the hole, the direction and the depth. Sources of drilling error 1. Marking and collaring errors 2. Inclination and directional errors Deflection errors 4. Hole depth errors 5. Undergauge, omitted or lost holes

17 Examples of drill-hole deviation Floor hump due to explosives malfunction - caused by drill string deflection Deflection caused by gravitational sagging of drill steel in inclined holes Deflection with and without pilot tube for Ø89 mm DC retrac bit / T51

18 Straight-hole drilling! Drilling More drill meters/shift Improved service life of drilling tools and machine Blasting Better control of fragmentation Better floor and wall control Reduced risk of fly-rock and vibrations Reduced amount of secondary blasting Loading and hauling Better fragmentation and smoother floor improves loading capacity and reduces costs Crushing Higher crushing capacity Planned amount of fines Quality holes are clean and stable drilled in the right position at the correct angle straight to the right depth

19 Drilling methods and commonly D&B Costs ( EUR / t ) Example, poor operator Bench height 5 m, hole depth 5.7 m Drill-hole 51 mm, pattern 2.34 m 2 (1.3m*1.8m) Driller wants to be sure : He drills 1.0 m too long holes! EXTRA COST per HOLE: Drillmeters: 1.0 drm * 3.5 /drm = 3.5 Explosives: 1.0 m * 1.24 kg/m * 2.0 /kg = 2.48 Labour (charging 0.5 /kg) 1.24 kg * 0.5 /kg = 0.62 Total = 6.60 Extra cost per drm 6.6 / 5.7 m = 1.16 /drm If drilling capasity was 30 drm/h, damage would be 34.7 /h What would be suitable salary ( /h) for the driller? + additional costs: loading and hauling, filling (possibly concrete) Hole diameter (mm)

20 Drilling for demolition Drilling machinery for demolition should be easily brought to site and moved inside the site. Hand held drills like pneumatic or electric top hammer and small rigs are commonly used. Sometimes together with thermic lance. Core drilling is used in demolition works in order to drill blast holes into concrete reinforced with steel bars.

21 Demolition without blasting For safety and sometimes economical reasons one should consider demolition without drilling and blasting. Hydraulic splitter is used in small-scale operations. It is effective also in rock material.

22 7. Occupational health and safety in drilling work related accidents for: mobile equipment hazardeous work areas emissions control noise control dust control fly rock / charging / straight-hole drilling falling rocks / wall control => safety is as much equipment as it is attitude

23 Safety issues of inpit operations Rollover from terrain bench - 35m drop Pit wall failure burying 3 drill rigs in rubble