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Published byNora May Modified over 8 years ago
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Blasting Hazards in Mining
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The use of explosives for blasting have inherent risks that must be considered for safe use
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Objectives Blasting hazards Types of blasting hazards MSHA regulations Prudent safe work procedures
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Consequences Loss of life Personal injury Property damage Loss of production Loss of jobs Liability issues
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Explosives Consist of: Types Blasting agents Detonator and initiating systems
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Class A Explosives Dynamite Cast boosters Cap sensitive emulsions Slurries Water gels
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Blasting agents Bagged or bulk ammonium nitrate (ANFO) Bulk emulsions Slurries Water gels which are not cap sensitive
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Initiating systems Electric blasting caps Detonating cord Shock tube systems Gas systems Miniaturized detonating cord systems
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Hazards Premature detonation Flyrock
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Premature Detonation
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Electrical Stray current Static electricity Lighting Radio frequency energy High voltage lines
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Equipment & Machinery Traveling over explosives Entanglement with blasting connections
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Handling Rough handling of explosives or explosive agents Using improper tools Undue pushing, retrieving while loading hole Making up primers in advance
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Storage Security Fire hazard Ventilation Mixing explosives & explosive agents
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Transportation Rough handling of explosives or explosive agents Mixing of explosives & explosive agents Fire hazard
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Smoking No smoking No matches or open flames
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Flyrock
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Reasons Failure to anticipate flyrock Failure to move to a safe location Failure to take cover in safe location Failure to obey blasting warnings or signals Failure to obey order of blaster
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Reasons Failure to follow MSHA regulations Failure to adequately cover shot Attempting to dig out or handle a misfire Depending on a cab for protection Driving over explosives & explosive agents
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Flyrock From Misfires Digging out or handling a misfire Failure to anticipate a misfire Failure to recognize a suspected misfire Failure to wait required time before investigating suspected misfire Failure to block off misfire area Failure to report suspected misfire
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After Gases Chemicals –Carbon monoxide –Oxides of nitrogen Effects –Suffocation –Pulmonary edema
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Lighting Cease loading until storm has passed Use AM radio just off local station & listen for static Call local weather station
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Heat/Pressure/Concussion Temp in excess of 150 degrees –Keep sparks & open flames a safe distance away Subfreezing temp –Take suitable precautions Excessive pressure –Care in loading holes Some explosives/agents are very sensitive to concussion –Care in loading holes
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Electric Sources Overhead power lines –Keep required distance away Radio and electric towers –Keep required distance away Equipment trailing cables –Remove cable from area Two way radios –Turn off
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Electric sources Cellular phones –Turn off Homes & business –Keep required distance away Blasting machines –Keep out of area until needed or use non-electric initiation Equipment & batteries –Remove from area
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Regulators MSHA DOT Federal Highway Administration Bureau of Alcohol, Tobacco, & Firearms State & local
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Regulations
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Storage Separate storage for detonators & other explosive material Separated when stored in same magazine Magazine areas clear for 25’ No combustibles within 50’ Use old explosives first
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Storage Stored according to brand & grade Stack no higher than 8’ Stored in nonconductive containers Stored in magazines
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Storage Ventilated, weatherproof & locked Bulk blasting agents stored in weatherproof containers Placards & warning signs Located in areas where a hazard will not be created Located away from blast area & power lines
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Storage Structurally sound Noncombustible Bullet resistant Made of non-sparking material Ventilated to control dampness & excessive heat
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Storage Kept clean & dry inside Lighted - not to create fire or explosion Unheated or heated - not to create fire or explosion Locked when unattended Exclusively for explosive storage
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Storage Electrical bonded when necessary Switches & outlets located outside Powder chests structurally sound Powder chests weather resistant Powder chests posted with placards &warning signs
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Storage Powder chest located out of blast area when loading complete Powder chest locked or attended Powder chest emptied at end of each shift Detonators & blasting agents separated in powder chests
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Transporting Transported without undue delay to blast or storage area Detonators in original packing Detonators & explosive agent separated by wood dividers Detonators & explosive agent in closed containers
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Transport Vehicles Maintained in good conditions Equipped with sides to protect cargo Separate cargo & passenger area Equipped with 2 extinguishers or fire suppression system Posted with warning signs
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Transport Vehicles Occupied only by necessary persons Attended or locked when parked Parking brake set Wheels chocked Engine off when not needed
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Transport Vehicles Non-sparking material in cargo space Non-sparking equipment secured in cargo area Have no zinc or copper exposed in cargo space Any enclosed screw-conveyor protected from friction/pressure
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Locomotives Not transported on locomotive Explosives insulated when carried on cars transported by locomotive
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Hoists Notify hoist operator of cargo Secured on hoist Not transported with mantrip
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Use Of Explosives Only trained person should handle Trainees work with experienced persons Check blast holes before loading Keep detonators & explosive separate until ready to load Make up primers only when ready for use
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Use Of Explosives Primers secured in explosive appropriately Proper connections between multiple detonating cords No tamping directly on primer No dropping of explosives/blasting agents on primers Unused explosives removed before blast is detonated
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Use Of Explosives Blast attended, barricaded & posted from unauthorized entry Vehicles not driven over explosives Once loading begins only activities related to loading shall occur Loading & blasting to proceed without undue delay All persons leave blast area before detonation except those necessary for blast ignition
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Use Of Explosives Person detonating shall protect themselves from flyrock & gasses Ample waning given to evacuate Clear exit routes provided Access route guarded or barricaded Post blast inspection Explosive material not loaded using drill stem equipment
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Use Of Explosives Initiation system follow manufacturer specifications Liquid hydrocarbons with specific flash points not used Waste oil not used with ANFO Misfire - not return to blast area for: –30 minutes if safety fuse & blasting caps are used –15 minutes other types of detonators
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Use Of Explosives Faces & muck piles examined for misfires Only work necessary to remove a misfire can proceed in a blast area Areas suspected of misfires shall be posted with warning signs
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Use Of Explosives Areas suspected of misfires reported to management, no later than end of shift All secondary blasts shall be initiated from one source
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Electric Blasting All detonators from same manufacture & have similar firing characteristics Kept shunted until connection to blasting line is made Kept shunted until immediately before blast No electrical circuits within 50’ of detonators at blast site Each blast circuit have safety switch or equivalent
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Electric Blasting One safety switch outside blast area in open position until person withdrawn Switches locked in open position until blast No leads connected until shot is ready Power sources capable of delivering sufficient current Blasting machines tested, repaired & maintained
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Electric Blasting Only blaster have control of firing device Blast connected in parallel limited to 25 milliseconds Blasting circuits tested with approved devices Continuity tests required Resistance tests required
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Non-electric blasting Visual checks required of all components Shock tube connects secured properly No connects between blast holes shall occur until all persons unnecessary for firing are clear
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Non-electric blasting Detonating line cut from spool immediately after explosive is positioned in hole Trunk line layout designed so detonation can reach all blast holes from 2 directions Detonators positioned to side of the detonating cord & pointed in direction etonation is to proceed Lead-in lines manually unreeled if connected to truck lines
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Non-electric blasting Initiation tested for continuity if gas tubes are used prior to blast Burning rate of safety fuse made know to all involved Sufficient safety fuse lengths Safety fuse damage from flyrock considered in preparation
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Non-electric blasting Fuse cut & capped in dry location Care taken when crimping fuse to blasting caps Safety fuse only ignited after fuse & explosives are in place Safety fuse ignited only by devices for such purpose 2 persons present when lighting safety fuse
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Extraneous Electricity Any blast area suspected of extraneous electricity shall be tested for such condition Electric blasting circuits shall not be grounded Any potential static electricity problem corrected before loading
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Extraneous Electricity Loading hose constructed of materials which produce minimal amounts of static electricity Wire-countered hose not used Loading equipment bonded & grounded Plastic tubes not used as hole liners if electric detonators are used
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Extraneous Electricity 15’ air gap between blasting circuit & electric power source During approach & progress of electrical storms, blasting suspended & take safe refuge All blasting lines & leads protected from any source of stray or static electricity
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Extraneous Electricity Only non-sparking tools used to open explosive containers or punch holes in explosive cartridges Tamping & loading poles made of wood or nonconductive materials
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Black Powder Only used when desired result can not be obtained with other explosive products Non-sparking containers Kept in enclosed cargo space while transporting
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Black Powder Securely closed at all times when within 50’ of magazine or open flame Securely closed within a building fuel- fired or exposed to electric heat element Securely closed where electrical or incandescent particle sparks could result in ignition Only transferred by pouring
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Black Powder Cleaned up promptly Misfires disposed of by washing stemming & powder from blast holes Holes not reloaded for at least 12 hours when blast holes have failed to break as planned
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Maintenance Any work on storage facility that may produce spark or flame requires removal of all explosive materials for 50’ distance Facility cleaned to prevent accidental detonation No vehicle containing explosives or oxidizers taken to shop or garage
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Maintenance No welding on bulk truck until truck has been washed & clean of explosive materials Permanent blasting lines properly supported, insulated & in good repair
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General requirements Damaged or deteriorated explosive disposed in safe manner Explosives not loaded where excessive heat could cause premature detonation When blasting sulfide ores & hot holes, measurement of blast hole temperature done before loading
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General requirements When blasting sulfide ores and hot holes, limit time between loading & initiation no more than 12 hours If suspected that explosive material is burning, evacuate area & not return for at one hour after burning stops No open flames or smoking permitted within 50’ of explosive materials
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General requirements Explosive materials protected from temperatures in excess of 150 degrees Explosive materials protected from impact, except during tamping sand during loading process
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Other regulatory agencies DOT - hazardous material transportation Federal Highway Administration - explosives transportation ATF - storage & interstate commerce of explosive materials State & local regulatory officials
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Company-specific procedures Employee training Mining methods Drilling at blast site Initiation process Proximity to dwellings or processes Factors Affecting Incidents
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Procedures
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Company Notifying employees & contractors of proposed blast Signs posted Audible signals Radio communication
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Meeting location before blast Safe distance from blast area Out of equipment & not relying on cab/windshield for protection Not in direct line of fire of blast Inside building away from blast Take Cover
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Loading blast hole Guarding/barricading roads & highways Communicating with blaster to advise of not safe to detonate Staying away for blast site with machinery/equipment & electrical apparatus when loading started Assisting Blaster
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Return to Blast Area How notified Staying away from blast smoke & fumes
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Employee notifies management & blaster Employee does not attempt to handle misfire Employee moves to a safe location until hazardous condition corrected Misfire - Unsafe Conditions
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New miner Annual refresher Site-specific Changes at mine in regards to blasting procedure Task training Training
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Mining Methods Understand highwall & bench hazards Scaling of highwall where blast preparation is taking place Barricading highwall areas where hazards exist Use of cones/berms to indicate edge of highwall Barricading or signs leading to blast area
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Drilling Procedures
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Size of drill hole must be decided Driller & blaster will review blast plan & inspect proposed area for unsafe conditions Must have experience & adequate knowledge of drill Inspection of drill
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Drilling Procedures Proper PPE of driller Drill holes to predetermine depths No drilling within 50’ of loaded or partially loaded holes Position drill safe distance from bench edge Position drill safe distance from highwall
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Drilling Procedures Make note to inform blaster of drilling condition found No angled or inclined drilling is permitted unless approved by blaster and management Use of safety lines when drilling adjacent to open faces outside drill
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Initiation Process
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Electric Initiation Follow MSHA regulations on electric detonation Know & understand hazards of electric detonation systems Blasting machines stored away from blast site until needed
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Electric Initiation Use only connections & hookups approved by product manufacturers Blast site cleared of all unnecessary equipment & persons All electric connections double checked & inspected Mechanized equipment kept clear of detonator leads & shock tubes
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Non-Electric Initiation Follow MSHA regulations on non- electric detonation Know & understand hazards of non-electric detonation systems Non-electric starters stored away from blast site until needed
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Non-Electric Initiation All non-electric connections double checked & inspected Shock tube detonators never be pulled until they break Mechanized equipment kept clear of detonator leads & shock tubes
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Control Of Blasting Hazard
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Proximity To Dwellings Procedures for blasting & storage of explosives near highways, roads, residential areas & business Follow MSHA regulations on storage of explosives & detonating devices & blasting Follow DOT regulations when transporting explosive agents on public roads
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Proximity To Dwellings Know state & local regulations Guard & block off roads Stop traffic on highways if in hazard zone Keep blast area required distance from homes, schools & business Advise all in area before blast detonation
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Control Blasting Hazard Contractor safety procedures Site security procedures Storage & handling Warning & alarm systems Take cover procedures Post-blast inspection procedure
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Hazard Identification Understand explosives are sensitive & handled with care Realize electricity is hazardous when working with explosives Never work with explosive when electricity is present Follow all explosive manufacturers recommendations
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Hazard Identification Use approved tools - improper tools can lead to incidents Flyrock incidents cause injury & taking cover is just one solution Only experienced persons shall handle explosives
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Blasters & Drillers Follow MSHA regulations Follow company rules Inform management problems Respect safety of mine employees Respect safety of areas adjacent to mine Control potential flyrock
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Contractors Informed of blasting hazards Know blasting warning signals Know location to be when blast is loaded & detonated Stay out of blast area Know when it is safe to return to blast area after detonation
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Contractors Don’t depend on equipment cabs to protect from flyrock Don’t handle suspected misfire Know who to notify if misfire is detected Stay out of blast fumes & smoke
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Site Security All necessary signs are posted Warning signals/signs utilized Roads barricaded or guarded Highway traffic stopped Employees & contractors notified Verify homes & business adjacent to blast site notified
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Storage & Handling Separate storage for detonators & explosive material Magazine kept clean & no combustibles allowed to accumulate Use old explosives first & store according to brand & grade Locked when unattended Exclusively for explosive storage
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Storage & Handling No smoking or open flames Follow precautions when transporting Handled by experience persons Non-experienced handle explosives under supervision of experienced Load blast holes using manufacturers recommendations Know & understand initiation system
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Warning & Alarms Employees & contractors know warnings & alarms System reviewed with employees & contractors to ensure familiarity Systems can consist of signs, audible signals & radio communication
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Take Cover Procedures Employees & contractors instructed on procedures Adequate time given for take cover Adequate distance considered Suitable protection considered Blaster/management ensure all employees protected
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Post-Blast Inspection Inspect after gases/fumes cleared Explosives have detonated & no detection of misfires exist Inspect ground conditions Inspect surrounding areas Communicate with guards & others on blast issues reported
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Blast Related Incidents
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Analysis Causes Correction/lessons learned Prudent safe work practices
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Causes Review of MSHA Fatalgrams & reports involving explosives Review of company incident reports
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Lessons Learned Review of MSHA Fatalgrams & reports involving explosives Review of company incident reports
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Safe Work Practices If there is something you do not understand, get answer now Once explosives are loaded at the blast area & within minutes of detonation is no time for second guessing No such thing as a little blast & small amounts of explosives can cause destruction & grief
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Safe Work Practices Shortcuts lead to disaster Never accept the “I think everything is OK.” Know by checking, double checking & asking all involved the blast is 100% before detonation Even if your part is very small in the blasting process, speak up if something doesn’t look right, smells funny or gives you wrong feeling Work as a team & communicate
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Last Words I didn’t think flyrock could go that far I thought they knew better not to force blasting caps I thought all roads were blocked & guarded - I don’t know where that person came from I don’t know why he thought windshield would stop flyrock I thought I told them not to handle suspected misfires
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