(a)Only competent persons shall be designated or permitted to handle explosives or do blasting. Only electric detonators of proper strength may be used and the use of delay electric detonators is prohibited for blasting coal or coal and other material. Primers shall be made up as needed for blasting and prepared in accordance with the safety standards of the Institute of Makers of Explosives or of the manufacturer of the explosives as approved by the chief; provided, however, that nothing provided in this subsection shall prohibit the use of permissible millisecond blasting in conformity with the requirements, exceptions, limitations, conditions, and restrictions on the use thereof established or hereinafter established by the Bureau of Mines of the United States Department of the Interio
Free access — add to your briefcase to read the full text and ask questions with AI
(a) Only competent persons shall be designated or permitted to handle explosives or do blasting. Only electric detonators of proper strength may be used and the use of delay electric detonators is prohibited for blasting coal or coal and other material. Primers shall be made up as needed for blasting and prepared in accordance with the safety standards of the Institute of Makers of Explosives or of the manufacturer of the explosives as approved by the chief; provided, however, that nothing provided in this subsection shall prohibit the use of permissible millisecond blasting in conformity with the requirements, exceptions, limitations, conditions, and restrictions on the use thereof established or hereinafter established by the Bureau of Mines of the United States Department of the Interior.
(b) Care shall be used in placement and drilling of holes. Test roof, face, ribs and timbers for dangerous conditions before drilling or preparing holes. Certified official or approved competent persons must test for methane with approved methane detectors before drilling with electric powered drills and before charging bore holes.
(1) Bore holes shall not be drilled beyond the back of the cut or cutting shot nor into the solid ribs, roof, or floor.
(2) Where it is impractical to undercut, top cut, or shear the coal face and solid shooting is necessary, depending shots are prohibited. The method of placing and firing holes is subject to approval by the chief.
(3) Bore holes shall be cleaned and checked to see that they are placed properly and are of correct depth in relation to the cut before being charged.
(4) To prevent blown-out or windy shots, all portions of the bore holes, where the height of the coal permits, shall have a burden in all directions of at least 18 inches before being fired.
(c) Charges shall not exceed one and one-half pounds in bore holes under six feet in depth. Charges exceeding one and one-half pounds but not exceeding three pounds may be used only if bore holes are six feet or more in depth, have a burden in all directions of at least 18 inches and Class A or Class B permissible explosives are used.
(d) Bore holes shall be charged with explosives in a continuous train with no cartridges deliberately deformed or crushed, with all cartridges in contact with each other, and with the end cartridges touching the back of the hole and the stemming respectively.
(e) Bore holes shall be tamped with wooden tamping bars, and shall be stemmed with at least 24 inches of incombustible material or at least one half of the length of the hole shall be so stemmed if the hole is less than four feet in depth. Water-filled plastic bags for stemming may be used under the following conditions:
(1) The bags shall be made of polyvinyl chloride not less than six mils in thickness or equivalent in tear resistance and noninflammability.
(2) The bore hole shall be stemmed with at least one water-filled bag not less than 15 inches in length and within one fourth of one inch of the bore hole diameter. Short bore holes may not accommodate the entire bag, but this shall be acceptable.
(3) The bags shall be equipped with self-closing valves or equivalent leakproof protection.
(4) To prevent puncturing, the water-filled bag shall be pushed gently into the bore hole until it touches the charge of explosives and shall not be tamped or forced.
(f) In mines where shooting is done on shift, all shots or series of shots shall be fired promptly after charging and in the following manner:
(1) Remove shunts or untwist ends of leg wires of electric detonators and connect to firing cable.
(2) Move away from face, paying out cable and being sure cable does not contact pipe, pan line or other material that may carry stray currents. Keep leg wires and firing cable up out of water.
(3) Take firing position in protected place around at least one solid corner or in an adequate shelter hole.
(4) Give ample warning before shots are fired and ascertain that all persons are in the clear. See to it that men are removed from adjoining working places when there is possibility of a shot breaking through.
(5) Unshunt ends of firing cable, attach to blasting unit, call “Fire! Fire!” with intervals between each warning and set off charge.
(6) Disconnect firing cable and reshunt ends.
(7) Wait for smoke to clear and immediate roof effect to take place.
(8) Return to face, reeling up firing cable and make tests of face, roof, ribs, and timbers for dangerous conditions. In mines classed as gassy, a certified official or approved competent person must make a gas examination on return to the face after blasting.
(9) If gas or other dangerous conditions are found that cannot be made safe in normal course of work, mark place out with DANGER sign and report to mine foreman or supervisor in charge.
(g) Holes shall not be drilled, charged, or fired in any place where methane gas can be detected at one percent or more on an approved methane detector.
(h) In mines where shooting is done from the surface with all men out of the mine, a separate blasting circuit must be provided with a switch kept locked when not in use for blasting or written approval of the chief of the division must be secured. Requests to use power or a signal circuit for blasting with all men out of the mine, shaft, or slope must state precautions taken to guard against electrocution and premature detonation hazards. Approval by the chief will be conditioned on compliance with these precautions, violations of which will be considered violations of this section of the law.
(i) Mixed charges shall not be charged or fired in any bore hole.
(j) The firing of adobe (mudcap) or other open, unconfined shots is prohibited in any mine.