Show premature explosions ons from f steam shovels and sparks spar ks BY SPENCER P HOWELL A recent premature explosion in a quarry that resulted in the death of nine men and the injury of several others was directly traceable to a spark from a steam shovel working under the face directly in front of the hole being loaded this accident and similar accidents on record in the bureau of mines indicates the necessity for pointing out the dangers in quarries of explosives being ignited by sparks emitted from steam shovels and locomotives and making recommendations for greater safety many premature explosions of which the following are examples have resulted from sparks both from steam shovels and passing locomotives A the premature explosion occurred during august 1920 at a limestone quarry in a foot drill hole loaded with 1000 pounds of high grade nitroglycerin and gelatin dynamites this hole had been loaded with pounds of 75 per cent strength gelatin dynamite pounds of 60 per cent st straight raight nitroglycerin dynamite and pounds of 50 per cent straight nitroglycerin dynamite but no stemming had been placed in the hole the loading the hole saw the spark enter the hole and was able to run a short distance before the explosion took place thus escaping serious injury the explosion of this first hole was transmitted to a nearby hole similarly charged the fall of rock from these two holes buried the steam shovel and some of the gang of men working around it B in september 1909 in the canal zone a steam shovel uncovered a misfired charge of dynamite while the dynamite was being picked up the steam shovel continued working nearby A spark from the shovel set fire to some loose dynamite spilled on the ground from the broken cartridges this fire was transmitted to a hole which was being loaded close by and caused a premature explosion one man was injured I 1 C in september 1912 in the canal zone a spark from a passing locomotive set fire to a piece of paper near dynamite that was being loaded into a hole the paper set fire to the loose dynamite cartridges which in turn caused the detonation without prior burning of unopened boxes of explosives near by none were injured D in august 1907 in the canal zone a hot cinder from a passing locomotive fell into a lot of prepared primers setting fire to the dynamite an explosion immediately followed none were injured E in september 1912 in the canal zone a spark from a passing locomotive explosive engineers U S bureau of mines set fire to the explosive in a drill hole causing a premature explosion injuring several men F in january 1907 in the canal zone a spark from a passing locomotive fell into an open black powder can igniting the powder the other cans near by were in turn ignited injuring several men recommendations for safety from the above mentioned accidents certain very important recommendations for safety can be made and these should be carefully observed vea 1 the general principle should always be followed that workmen should never be allowed at the base of a quarry face within the zone of possible danger from falling rock after the work of loading the hole has begun and the presence of workmen in the area between the line of holes and the face should be avoided 2 before loading is begun the steam shovel and locomotives should be withdrawn from the face of the quarry to such a distance that under no circumstance could sparks from them be carried to the explosive in the holes or on the ground above or around it or if such equipment is not removed it should not be operated 3 if there is any unavoidable danger from sparks or cinders a canopy should be provided which will protect the explosive from flying sparks A covered hopper may be used for black blasting powder 4 where an unexploded charge is uncovered by the steam shovel operations should cease until all of the explosive has been recovered and removed to a safe distance 5 every piece of paper or other inflammable material should be removed from the vicinity where explosives are placed during loading operations 6 primers should be kept in a portable metal box with a hinged cover and should not be stored close to the explosive especially while the holes are being loaded 7 Unopened boxes of explosive should not be stored close to the hole being loaded but should be opened at a distance from it and brought up as needed U S bureau of mines reports of investigations |