Prevention and treatment of Misfire

Prevention and treatment of misfire

misfire, also known as misfire, refers to the phenomenon that the explosive that is expected to explode does not explode. The phenomenon that explosives, detonators or other initiating explosive devices cannot be detonated is called misfire

I. causes of blind blasting

1. Blind blasting caused by misfire of fire detonators

(1) the detonator fuse core is too thin or broken, the reinforcing cap is blocked, and the fuse is specifically related to the detection cord on medical equipment and the detonator is damp and deteriorated during transportation, storage or use, and the detonator is not well connected with the fuse, resulting in blind blasting of detonators

(2) the fuse is damaged or pulled off from the detonator due to carelessness during charging and filling; Missing points during firing, improper firing sequence, etc. will lead to blind firing

2 · electric detonator produces blind shot

(1) the bridge wire and foot wire of the electric detonator are not welded well, the ignition head is separated from the bridge wire, and the delay fuse does not ignite the primary explosive, etc

(2) the detonators are damp, or detonators of different manufacturers, different batches and different structural properties are used in the same circuit, or the circuit resistance configuration is unbalanced, and the resistance difference of detonators is too large, resulting in the current imbalance, so that the electric energy obtained by each detonator is greatly different. The detonators that obtain sufficient detonating electric energy detonate first and break the circuit, causing other detonators to fail to detonate

(3) short circuit, open circuit, missed connection, grounding or wrong connection of electric explosion circuit

(4) the initiation power supply is insufficient, and the current through the detonator is less than the quasi explosion current; In the water hole, especially in the water with dissolved Trinity explosives, the poor insulation of the line connector causes current shunt or short circuit

3 · misfire caused by detonating detonating cord

(1) due to quality problems, detonating cord can also improve productivity or get damp and deteriorate, and the detonating capacity is insufficient

(2) the core of detonating cord is infiltrated with oil

(3) when connecting the detonating cord, the lap length is not enough, the direction of detonation transmission is reversed, and the detonating cord is connected into an acute angle, or the detonating cord is damaged during laying; When the initiation is delayed, the first explosive package will break the initiation road

4 · misfire caused by misfire of the detonating arm detonating system

(1) there are impurities in the detonating tube, and the length of breaking the explosive is large (15cm for breaking the explosive) 0

(2) the bayonet at the connection between the detonating tube and the booster tube or the millisecond detonator is not tight, and foreign matters (such as water, mud and sand, rock cuttings) enter the detonating tube. The pipe wall is damaged and the pipe diameter is narrowed; The detonating tube is excessively knotted and folded in half

(3) when detonators or detonating cords are used to detonate detonators, they are not tied firmly, there is water in the four-way connector, the road covered by the protection is damaged, or the detonator energy accumulation hole faces the detonation direction of the detonator, and the detonator crosses the detonation arm, etc

(4) during delayed initiation, the vibrating flying stones produced by the first stage blasting damage some roads of delayed detonation transmission

II. Prevention of blind blasting

1. Blasting equipment should be properly kept and strictly inspected. It is forbidden to use blasting equipment whose technical performance does not meet the requirements

2. The resistance difference of electric detonators used on the same series branch should not be greater than 0.80, and important projects should not exceed 0.3n

3. Fuses with different burning rates should be used in batches

4. Improve the quality of blasting design. The design contents include blast hole layout, detonation mode, delay time, road laying, detonation current, road detection, etc. For important blasting, road simulation test must be carried out when necessary

5. Improve blasting operation technology to ensure construction quality. Ensure that the fuse is closely connected with the detonator and the detonator cannot be separated from the cartridge when detonating the fire detonator; For electric blasting, it is necessary to prevent missed connection, wrong connection and broken pin wire. The circuit grounding resistance shall not be less than lx10'q, and it is necessary to often check whether the switch and line connector are in good condition

6. When working face with water or underwater blasting, reliable waterproof measures should be taken to avoid dampness of blasting equipment. If necessary, the underwater waterproof test shall be carried out for the detonating equipment, and insulation measures shall be taken at the connecting parts

III. treatment method of blind blasting

1. Blind blasting treatment of Exposed Blasting

blind blasting treatment of exposed blasting, it is allowed to carefully remove part of the sealing mud by hand, and relocate a new primary explosive package on the original primary explosive package, plus the sealing mud blasting

2. Blind blasting treatment of shallow hole blasting

(1) after inspection and confirmation that the blasting line of the blast hole is in good condition, it can be detonated again

(2) parallel hole charging blasting. Parallel eye distance blind shot orifice shall not be small], 0.3 for shallow eye medicine pot method, The distance between the parallel eye and the edge of the blind gun medicine pot shall not be 4h] "0.5 shame. In order to determine the direction of the parallel eye, it is allowed to use plasticizers, petrochemical industry and any non ecological sustainable materials from the blind and try to reduce the use of plasticizers, petrochemicals and any non ecological sustainable materials in the production process. The length of the muzzle taken out shall not exceed the blood filler.

(3) tools made of wood, bamboo or other materials that do not cause sparks, gently detain most of the filler in the blast hole and induce explosion with shaped charge.

(4) Use a remotely operated air and water pipe to blow out the blinding filler and explosives at a safe distance, but measures must be taken to recover the detonator

(5) blind shots should be handled on duty. If the situation of blind shots (the number of blind shots, the direction of the blast hole, the number of charges and the location of the detonating charge, the treatment method and the treatment opinions) cannot be handled or not completed on the shift, it should be clearly handed over on site, and the next shift should continue to deal with it

demolition blasting blind shot treatment

(1) it is strictly prohibited to pull out the electric detonator pin wire or detonating tube from the blind shot

(2) take measures to eliminate unsafe factors caused by changes in blasting conditions. The second blasting can be carried out according to the conventional blasting requirements after all personnel withdraw to the safe area

(3) the residual detonators of unexploded ordnance collected from the blind shot shall be disposed of and destroyed in time with the consent of the blasting leader, and the location, dosage and current condition of each blind shot shall be recorded and archived one by one

4. Blind blasting treatment of deep hole blasting

(1) if the blasting road is damaged and the minimum resistance line has not changed, it can be re connected and detonated; If there is a change in the minimum resistance line, the safety distance should be verified and the warning range should be increased before the line is detonated

(2) charge and detonate with parallel holes at a distance of not less than 10 times the diameter of the blast hole from the blind hole. Blasting parameters shall be determined by the blasting leader

(3) if the explosives used are non water resistant nitrate hinged explosives and the hole wall is intact, take out part of the filler, fill the hole with water to make it invalid, and then make further treatment

5. Blind blasting treatment of blockhouse blasting

(1) if the wire, detonating cord or detonating tube of the detonating path can be found, and the detonator can detonate normally after inspection, the minimum resistance line can be re measured, the warning range can be redrawn, and the line can be detonated. It is all due to the increase of external demand

(2) remove the stuffing along the shaft or flat blockhouse, re lay the road, connect the line to detonate or take out the explosives and detonators