Blasting Hazards in Mining

The use of explosives for blasting have inherent risks that must be considered for safe use

Objectives Blasting hazards Types of blasting hazards MSHA regulations Prudent safe work procedures

Consequences Loss of life Personal injury Property damage Loss of production Loss of jobs Liability issues

Explosives Consist of: Types Blasting agents Detonator and initiating systems

Class A Explosives Dynamite Cast boosters Cap sensitive emulsions Slurries Water gels

Blasting agents Bagged or bulk ammonium nitrate (ANFO) Bulk emulsions Slurries Water gels which are not cap sensitive

Initiating systems Electric blasting caps Detonating cord Shock tube systems Gas systems Miniaturized detonating cord systems

Hazards Premature detonation Flyrock

Premature Detonation

Electrical Stray current Static electricity Lighting Radio frequency energy High voltage lines

Equipment & Machinery Traveling over explosives Entanglement with blasting connections

Handling Rough handling of explosives or explosive agents Using improper tools Undue pushing, retrieving while loading hole Making up primers in advance

Storage Security Fire hazard Ventilation Mixing explosives & explosive agents

Transportation Rough handling of explosives or explosive agents Mixing of explosives & explosive agents Fire hazard

Smoking No smoking No matches or open flames

Flyrock

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

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

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

After Gases Chemicals –Carbon monoxide –Oxides of nitrogen Effects –Suffocation –Pulmonary edema

Lighting Cease loading until storm has passed Use AM radio just off local station & listen for static Call local weather station

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

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

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

Regulators MSHA DOT Federal Highway Administration Bureau of Alcohol, Tobacco, & Firearms State & local

Regulations

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

Storage Stored according to brand & grade Stack no higher than 8’ Stored in nonconductive containers Stored in magazines

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

Storage Structurally sound Noncombustible Bullet resistant Made of non-sparking material Ventilated to control dampness & excessive heat

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

Storage Electrical bonded when necessary Switches & outlets located outside Powder chests structurally sound Powder chests weather resistant Powder chests posted with placards &warning signs

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

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

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

Transport Vehicles Occupied only by necessary persons Attended or locked when parked Parking brake set Wheels chocked Engine off when not needed

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

Locomotives Not transported on locomotive Explosives insulated when carried on cars transported by locomotive

Hoists Notify hoist operator of cargo Secured on hoist Not transported with mantrip

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Maintenance No welding on bulk truck until truck has been washed & clean of explosive materials Permanent blasting lines properly supported, insulated & in good repair

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

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

General requirements Explosive materials protected from temperatures in excess of 150 degrees Explosive materials protected from impact, except during tamping sand during loading process

Other regulatory agencies DOT - hazardous material transportation Federal Highway Administration - explosives transportation ATF - storage & interstate commerce of explosive materials State & local regulatory officials

Company-specific procedures Employee training Mining methods Drilling at blast site Initiation process Proximity to dwellings or processes Factors Affecting Incidents

Procedures

Company Notifying employees & contractors of proposed blast Signs posted Audible signals Radio communication

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

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

Return to Blast Area How notified Staying away from blast smoke & fumes

Employee notifies management & blaster Employee does not attempt to handle misfire Employee moves to a safe location until hazardous condition corrected Misfire - Unsafe Conditions

New miner Annual refresher Site-specific Changes at mine in regards to blasting procedure Task training Training

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

Drilling Procedures

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

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

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

Initiation Process

Electric Initiation Follow MSHA regulations on electric detonation Know & understand hazards of electric detonation systems Blasting machines stored away from blast site until needed

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

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

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

Control Of Blasting Hazard

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

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

Control Blasting Hazard Contractor safety procedures Site security procedures Storage & handling Warning & alarm systems Take cover procedures Post-blast inspection procedure

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

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

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

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

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

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

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

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

Warning & Alarms Employees & contractors know warnings & alarms System reviewed with employees & contractors to ensure familiarity Systems can consist of signs, audible signals & radio communication

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

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

Blast Related Incidents

Analysis Causes Correction/lessons learned Prudent safe work practices

Causes Review of MSHA Fatalgrams & reports involving explosives Review of company incident reports

Lessons Learned Review of MSHA Fatalgrams & reports involving explosives Review of company incident reports

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

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

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