Explosives and Accessories for Blasting in Underground Coal Mines

Explosives Division of GULF OIL Corporation Limited manufactures a wide range of products for use in underground coal mines. It pioneered the development and introduction of permitted category slurry explosives for use in underground coal mines for the first time in the world.

The company manufactures ‘permitted’ category electric Instantaneous and Delay Detonators, Slurry explosive of P1, P3 & P5 categories and PETN detonating cord for gallery blasting. The permitted category products can be safely used in underground coal mine atmosphere containing methane-air and coal dust-air mixtures. Accuracy of firing times of delay detonators eliminate overlap and significantly contributes to better breakage, vibration control and less damage to underground
coal mine roof. Slurry explosives generate very low levels of toxic after-blast fumes and produce more round coal.

Product Range and their Application

‘Permitted’ Explosives

Godyne (P1) is a cap-sensitive, aluminized, P1 category slurry explosive, which has been approved by the Director General of Mines Safety (DGMS), Ministry of Labour, Government of India for use in gassy coal mines / seams of Degree I gassiness for blasting in coal after it has been mid-cut, under-cut or over-cut. Maximum charge per shothole allowed is 1000 grams. Godyne can be used for blasting in stone drifts.

Monodyne (P1) is a cap-sensitive, aluminized, P1 category slurry explosive, which has been approved by DGMS for use in gassy coal mines / seams of Degree I gassiness for blasting in coal after it has been mid-cut, under-cut or overcut. Maximum charge per shothole allowed is 1000 grams. Monodyne is stronger than Godyne and ecommended for use in very hard coal. Monodyne is better suited for blasting in stone drifts and seams containing stone bands.

Permadyne (P3) is a cap-sensitive, aluminized, P3 category slurry explosive, which has been approved by DGMS for use in gassy coal mines / seams of Degree I, II & III gassiness for blasting in coal after it has been mid-cut, under-cut or overcut. Maximum charge per shothole allowed is 800 grams.

Pentadyne (P5) is a cap-sensitive, aluminized, P5 category slurry explosive, which has been approved by DGMS for use in gassy coal mines / seams of Degree I,II & III gassiness for blasting off the solid (B-O-S) in coal or after the face has been under-cut, mid-cut or over-cut. Maximum charge per shothole allowed is 565 grams for blasting off the solid in coal.

‘Permitted’ Electric Detonators

Permitted category electric detonators consist of a Zinc- Copper coated steel shell filled with desired dosage of Penta Erythritol Tetra Nitrate (PETN) as base charge and a mixture of Lead Azide, Lead Styphnate and Aluminum Powder (ASA mixture) as priming charge. ASA mixture is
sensitive to flame while PETN is sensitive to the shock wave generated by the ASA mixture. In delay detonators, a pyrotechnic delay element is placed above the ASA mixture, which provides the requisite delay. Judicious use of delay detonators results in better fragmentation, greater vibration control and causes lesser damage to roof of the
coal seam.

Electric detonators are fitted with an electric fusehead having firing precision and consistency. The fusehead assembly is crimped to the detonator shell using a PVC plug that offers good resistance to water ingress when loaded in watery drillholes. The twin PVC coated lead wires have good di-electric strength and abrasion resistance. The bare
ends of the lead wires are shunted for protection against stray currents.

In Instantaneous Electric Detonators, the flame generated by the fusehead initiates the ASA mixture, which detonates the PETN base charge. In delay detonators, the fusehead ignites the pyrotechnic delay element, which conveys theflame to the ASA mixture, which in turn,
detonates the PETN.

Instantaneous Electric Detonator EDG is a permitted detonator for blasting coal after it has been under-cut, mid-cut or over-cut and
approved by DGMS for use in gassy seams of Degree I, II & III gassiness. It offers a reliable means of controlled, simultaneous
initiation of explosive charges in the shotholes. Instantaneous Electric Detonators are of No.6 strength. Both the lead wires are white in colour.

Coal Delay Detonator CDD is a permitted delay detonator used for Blasting-Off-The- Solid (B-O-S) in coal and approved by DGMS for use in gassy seams of Degree I, II & III gassiness. They are available in delay numbers 0 & 1 to 6 with a nominal time interval of 25 milliseconds between successive delay numbers. The delay numbers are embossed
on the bottom of the shell and also displayed with tags on the lead wire. Coal Delay Detonators are of No.6 strength. Lead wires are blue and white in colour.

G-Cord - ‘Permitted’ Detonating Cord (for Gallery Blasting)

G-Cord is a low grammage PETN detonating cord that assures reliable non-electric initiation in gallery blasting method of mining coal. G-Cord is a flexible cord containing a uniform PETN core of 4.5±0.5 grams/meter.
It ensures positive initiation of cap-sensitive permitted explosive, which lies in contact along the length of the fuse. The PETN core is encased in various protective coverings developed to withstand abrasion and exposure to water. A properly primed No.6 strength detonator reliably initiates it. Care should be taken during charging to ensure that formation of kinks, loops, cross-over do NOT take place inside the shothole. The colour of the cord is light green.

Product Specifications

Explosives

Detonators

• Detonators have an identification mark on the shell bottom.
  
  
• The alphabets IDL are marked on the PVC crimping plug.

Packaging

Explosives

Explosive is packed in blow moulded tube with cap or polythene film clipped on both ends. The cartridges are placed in polythene bags and packed in corrugated fiber board case. 25 kg of explosives are packed in a case. Markings on the case indicate manufacturer’s name, product name, cartridge size, cartridge weight, batch number, case number, date of manufacture, net weight and gross weight.

Detonators

Instantaneous Electric Detonators (EDG): 25 Detonators are made into a bundle ensuring that all lead wire ends are folded within the bundle. Two such bundles are wrapped in kraft paper to make a packet. Commensurate to length of lead wire, requisite numbers of packets
are packed in corrugated fiberboard case. Markings on the case indicate manufacturer’s name, product name, lead wire length, quantity, batch number, case number, date of manufacture, net weight and gross weight.

Coal Delay Detonators (CDD):Each case contains detonators of the same delay number. 5 detonators are held in a bunch keeping lead wire ends folded within and 5 such bunches are packed to make a larger bundle of 25 nos. Two such bundles are wrapped in kraft paper to form a packet of 50 Nos. Commensurate to length of lead wire, requisite
numbers of packets are packed in corrugated fiber board case. arkings on the case indicate manufacturer’s name, product name, wire length, delay number, quantity, case number, date of manufacture, net weight and gross weight.

Precautions

• Do NOT subject explosives and detonators to impact, friction or fire.
  
  
• NEVER force a detonator into explosive cartridge. Always use pricker made of non-sparking material.
  
  
• NEVER hold the detonator shell while unfurling the wire for use. Always hold the leadwire about 5 cms away from crimp portion to avoid any pressure coming on the fusehead assembly.
  
  
• Do NOT handle electric detonators while wearing woolen or synthetic clothes or in the vicinity of Cell phones, Walkie-Talkies, etc.
  
  
• Always keep the ends of leadwire or blasting cable shorted and unhook just prior to connections. Disconnect the blasting cable from the exploder if circuit needs to be checked.
  
  
• Always use a sharp knife to cut detonating cord. Never subject the cord to impact or friction.
  
  
• Remove coal drill cuttings from the shothole before charging explosives. Do NOT allow the explosive to get contaminated with coal dust.
  
  
• Do NOT carry out charging of explosives during an approaching storm or when there is lightning activity in the blast area. Vacate the blast area and resume operations only after the storm has passed. - Do NOT attempt to fight explosive fires.

Statutory Classification and Shipping Information

Search GOCL

See Also:

All Explosives Division Products

All Gulf Products