MNG 331 Final Assignment with verified solutions Save

Match the following event to its cause in the fragmentation process. - ANSWERSFractures extend to free face → Gas Pressure Crushing and grinding in moving of muckpile → Secondary Fragmentation Crushing around the hole → Shock Wave Rotation of fragments → Momentum Who invented the blasting cap? - ANSWERSAlfred Nobel Who invented dynamite? - ANSWERSAlfred Nobel The purpose of explosives is to break rock so we can easily: - ANSWERSload, crush, haul, dig it What is the most efficient way to use explosives? - ANSWERS(Minimize energy expended on making: Air blast, ground vibrations, and flyrock, Maximize energy used to break rock to requirements) On average, how much explosives does the United States use every year? - ANSWERS6 billion pounds The goals of the course include: - ANSWERSTo be knowledgeable in the subject and be confident and able to design blasting shots. The course objectives include: - ANSWERSObtain an understanding of explosives and explosive products, and the ability to apply this to the breakage of rock in an environmentally acceptable and safe manner. Are Explosives affected by freezing temperatures? - ANSWERSTrue Water gels and slurries contain: - ANSWERSAmmonium Nitrate (AN), Fuels The difference between detonation and deflagration is dictated primarily by which explosive property? - ANSWERSSonic velocity of the explosive mixture. In wet holes, explosive density should be? - ANSWERSgreater than 1, the hole should be dewatered, and a water resistant explosive should be used. Does Propagating ground reduce misfires. - ANSWERSNo it does not Is it possible to get a blend density that is higher than the density of 100% emulsion? - ANSWERSYes it is A moderate variation of the amount of fuel oil in ANFO will affect? - ANSWERSenergy, production of fumes, sensitivity, and velocity. The relative bulk strength of an explosive is relative to? - ANSWERSANFO. Which of the following is not an advantage of Gassed Emulsion? - ANSWERSDoes not require special equipment to load. Permissible explosives are? - ANSWERSlow flame, classified for use in coal mines, and used in underground operations that are classified "gassy." Black Powder is a? - ANSWERSDEFLAGRATING explosive product Which is the highest density explosives product? - ANSWERSCast booster When considering fuel content in ANFO? - ANSWERSit is typically preferred to be overfueled rather than underfueled. Which explosive has the least water resistance? - ANSWERSANFO Detonation velocity is dependant on: - ANSWERSExplosive type, Confinement, Charge diameter, and Priming Which of the following statements is incorrect regarding propagating ground? - ANSWERSReduces mis-fires Which type of initiation system lingers as a player in the market due to permissibility? - ANSWERSElectric. If 10 blasting caps are wired in parallel and each blasting cap is 3 Ohms, - ANSWERSthe total resistance of the circuit will be 0.3 Ohms. Are Electronic detonators accurate to 1 microsecond. - ANSWERSNo they are not Non electric systems are safe to use in the presence of which of the following: - ANSWERSstray electricity Which initiation system is traditionally known to have cap scatter of at least +/- 5%? - ANSWERSNonel Which type of initiation system is used most effectively for vibration control? - ANSWERSProgrammable Electronic If 20 electric blasting caps are wired in series and the resistance of each cap is 2.5 Ohms, - ANSWERSthe total resistance is 50 Ohms. The ALL FIRE current of a standard electric cap is 250 milliamps, and the NO FIRE current is 50 milliamps. - ANSWERS Nonel can be cut and spliced where? - ANSWERSOnly on the lead line. Commercial detonating cord contains which of the following explosives? - ANSWERSPETN What primary explosive is typically used in commercial detonators currently being produced? - ANSWERSLead Azide What is the safety factor of a blaster's multimeter when checking an electric blasting cap? - ANSWERS10 Which of the following are correct about a safety fuse? - ANSWERSIt is designed to burn at 40 seconds per foot, its burning rate varies with moisture content and age, and its burning rate varies with altitude. Nonel comprises a hollow tube with? - ANSWERSdusting of HMX and Aluminum. For bench blasting a 4 inch hole loaded with ANFO, the burden and spacing should be: - ANSWERS8 x 12 ft If a large void is encountered during drilling, the hole should be loaded as follows: - ANSWERSDeck through the void with stemming, reprime above decking and continue loading Hard toe is caused by: - ANSWERSToo high a burden at the toe, insufficient energy at the bottom of the hole, bad drilling, mis-fires The most effective way to produce smaller rock is to - ANSWERSincrease powder factor The most complete fragmentation occurs? - ANSWERSaround the powder Oversize found in the middle of a muckpile is most likely a potential sign of? - ANSWERSa mis-fire The column density of a 3.5 inch hole loaded with bag ANFO is how many pounds per foot of hole? - ANSWERS3.5 The jointing and bedding in a limestone ledge will? - ANSWERSdetermine the suitability for jetty stone, control face profile, determine the best blasting direction Primers should only be assembled? - ANSWERSat the time of use, not be tamped, not have cartridges above 4" in diameter be dropped on them in the blast hole A good starting place for powder factor in bench blasting is? - ANSWERS0.5 lb/ton or 1 lb/yd3 Oversize will be a problem if the blast hole spacing is? - ANSWERS2 to 3 times the joint spacing. For blasting massive rock, which is the most important rock strength? - ANSWERSTensile Having a face height too low normally results in? - ANSWERSpoor breakage, too small of powder factor, flyrock, stemming ejection Which post blast phenomenon is the key indicator of insufficient delay on the back row of a bench blast... - ANSWERSHint... This is the one discussed in class. Several of these may be indicators, but only one is the "KEY" indicator. Think about the picture of a man walking in what seems to be a muckpile. Where is this muckpile? Rock from the blast on the bench behind Having too high of a face height can result in? - ANSWERSdrilling inaccuracies, flyrock, and toe. For the use of delays in a blast, which of the following are correct? - ANSWERSUsing delays reduces ground vibrations, there are optimum delay periods for minimum vibration, there are optimum delays for fragmentation. The fragmentation process includes? - ANSWERSdynamic shock wave fracturing the rock, tensile reflection at the free face, gas pressure induced radial fracturing, crushing and grinding caused by movement. Increasing degrees of freedom in blasting results in? - ANSWERSincreased fragmentation. The rules of thumb for minimum delay period are: - ANSWERS1 ms per foot of burden hole to hole (on same row), 3 ms per foot of burden row to row, and 3 ms per meter of burden hole to hole (on same row) Bench blasting is the most common form of blasting because: - ANSWERSIt's easy to drill vertical holes, Free face to blast allows easy breakage, Low cost blasting. Under MSHA regulations, a vehicle carrying explosives must be: - ANSWERSmaintained in good condition, equipped with sides higher than the explosive transported, equipped with a non-sparking cargo space, have dry chemical fire extinguishers, and be secured while parked with the brakes set, wheels chocked off, and the engine shut off. The person most likely to be injured during a blast is: - ANSWERSBlaster If a blast is delayed more than 72 hours, then.... - ANSWERSThe operator shall notify the appropriate MSHA district office. Flyrock is caused by? - ANSWERSinsufficient burden, mud seams and cavities, improper timing, stemming that doesn't hold well (all of the above.) Which of the following causes the most fatalities in blasting? - ANSWERSFailure to clear the blasting area The principal hazard associated with initiation system is - ANSWERSlightning. Under MSHA regulations, "the area where explosive material is handled during loading included..." - ANSWERSis defined as the.... Blast Site Under combined MSHA and OSHA regulations, the drilling of holes next to holes being loaded or already loaded is only allowed at a distance farther than... - ANSWERS50 ft, 30 ft if a barrier is used. It is important to select blast guards that are: - ANSWERSTrustworthy Persons assigned to securing a blast site during blasting operations should be? - ANSWERStrained, properly equipped, and have knowledge of procedures. Static electricity is a problem for initiation systems and is most prevalent in: - ANSWERSdry conditions It is important as a blaster to be confident in blast designs and make sure that all conditions on the blast match those that the blast was designed for. - ANSWERSTRUE You should NOT fire blasts from the same place? - ANSWERSno matter what the orientation or location of the blast is at a particular mine site. If a misfire is suspected, the blaster should first... - ANSWERSWait for 15 minutes unless safety fuse is being used. What is the minimum distance permitted for smoking or open flame from explosives: - ANSWERS50ft When setting up a seismograph, the geophone should be placed.... - ANSWERSBuried in the ground or weighted down by sandbags to insure proper coupling with the soil If a house if 500 feet from a blast? - ANSWERSthe air blast will arrive 0.5 seconds after the first ground vibrations. Under OSM guidelines, what is the scaled distance that should be used when blasting between 301 and 5000 feet from a structure (without seismic monitoring)? - ANSWERS55 Most people can easily tell the difference between ground vibrations and airblast. - ANSWERSFALSE The OSM guidelines state a scaled distance of 55 ft should be used for blasting 450 ft. from a structure if you do not use seismic monitoring. - ANSWERS When filling out a blasting record, the following should be completed: - ANSWERSdate with the time of blast, signed by blaster, have a sketch of the blast with its exact position, have number of holes, max pounds per delay, and delay sequencing, and all lines filled with none left blank. Type 5 magazines are? - ANSWERSdrop trailers or bulk product bins. How much explosives can you detonate per delay to maintain a scaled distance of 50 with the closest structure 400 feet away? - ANSWERS64 lbs DOT regulates? - ANSWERSTransportation of explosives on public roads and assignment of explosives 1.1, 1.4, and 1.5 labeling. For the storage of explosives and blasting agents, which of the following is correct? - ANSWERSExplosive magazines should not display explosives signs, with the exception of type 5 magazines. All explosives storage areas should have perimeter signs displayed in such a way that a bullet passing through a sign does not have a clear line of sight to a magazine. To transport explosives on a public road in a vehicle that requires DOT placards, the driver is required to have a? - ANSWERSshipping manifest, fire extinguishers, a written route plan, and a commercial driving license with hazardous materials endorsement. ATF regulates? - ANSWERSthe storage of explosives and sale of explosives. Which of the following can be stored in an explosives magazine with class "1.1" explosives? - ANSWERSNon-sparking tools necessary for magazine operation. Pre-blast surveys are useful for new operations, but are a double edged sword with regard to? - ANSWERSnew housing and existing blasting operations Ways to reduce airblast include - ANSWERSgood explosives confinement, elimination of detonating cord, and avoiding blasting during temperature inversions. According to ATF regulations, how much explosives could be stored in a "barricaded magazine" that is 850 feet from an inhabited building? - ANSWERS500 lbs You are required to maintain a scaled distance of 50 and you have 100 lb. per delay in your regular blast pattern. - ANSWERSYou can come up to 500 ft from the neighboring houses before you have to modify your blast pattern. The ploys you are likely to experience in a court case are: - ANSWERSYour blaster is incompetent, your blaster was negligent, your blaster has no respect for other people's property. Pre blast surveys are: - ANSWERSOnly mandatory by federal law for the permitting of new mining operations under OSM control, useful to establish the condition of nearby building before blasting, and best performed by a qualified, experienced vibration or engineering consultant of company. To best protect yourself and your company from unwarranted damage claims you need? - ANSWERSAccurate blasting records and seismograph records of your blasts