EXPLOSIVE HISTORY:LEARN ON HOW IT BEGINS

An explosive is any chemical compound that is capable of undergoing instantaneous detonation under the supply of an impulse (high VOD shock wave) like fire, lightening, heat, friction, shock. Such compound at the point of detonation releases high energetic shock and gas energy which result into Explosion (increase in volume) under an exothermic reaction. Explosive energy can be hazardous big not properly managed. Explosives are only design for war (military) and peace (Mining) other usage (terrorist) is assumed to be illegal.

Explosive in 1627 was know only within the use of black powder for the fragmentation of rock mass into smaller size. The idea of breaking rock with Explosive was start in Hungary in year 1627 February.

Rock mass is a solid mineral Resources containing various mineral grains bonded together by cementing minerals like calcite, gypsum, quartz. This high strength bond between rock grains makes it more difficult to fragment in the 1500s. Thou inventory of Explosive into mining for blasting diver ways of rock breaking was identified with the Egyptians in Bible story.

The use of thermal expansion principle, use of impact load, chiseling approach and collision were some of the ways Stone age miners gets their rock mass fragmented. Even biblically during the building of Solomon temple in the city of Jerusalem, the king assign strong men to the quarry to get boulders for the building foundation.Therefore, use of Explosive as a means of breaking rock appears as a great solution to humanity problem. Explosive genealogy was traced from black powder which was claimed to be first used in China for fire walks to pulminating gold, pulminating mercy.

Then down to the Liquid Explosive called Nitroglycerin (NG). This NG is a liquid Explosive with high sensitivity. It sensitive to shock and therefore highly dangerous. During the time of Nitroglycerin Explosive various scholars like Alfred Nobel and others alongside with his brother work on how to make this Explosive chemical industrially safe for usage, handling, and transportation. During one of those days, Nobel brother ?Emil) alongside with others were killed by explosion accident on the base of Nitroglycerin Explosive in one of Alfred Nobel Laboratory.

READ ABOUT AFRED NOBEL 

At that period, charge drill hole with NG is something done with great fear and trembling. A view on how this was done shows that, the Nitroglycerin Explosive (in a bottle) is lower gently into the how with a thread or rope. Any mistake of suddenly drop of the bottle result into instantaneous detonation which will factually claim the life of the blasters men. This becomes a great challenge to the mining Engineers, a great challenge to the Explosive producing companies and a great issue to blasters.

Thou after black powder was used in mining industry for 227 years, due to it limit in shock wave energy, gun gotten was invented in 1854 but the use was stopped immediately.Nitroglycerin was invented by Sobrero in 1846 as a medicine for Angina pectoris, before Alfred Nobel decided to work on combining Nitroglycerin with Kieselguhr to produce Nitroglycerin dynamite in sweden year 1865. Later Alfred Nobel further his research on gun cotten by combining gun cotten and Nitroglycerin to produce Gelatin Dynamite Explosive. These Explosive products then we're highly expensive and was weathering mining profit margin.

 In 1950's ANFO (Ammonium Nitrate and Fuel oil) was invented. This was a great move in mining industry phase as the challenge of cost implication on Explosive was solved and lighten. The only issue was the water resistance challenge. ANFO become insensitive and become hazardous (possiblity of misfire) when use in a watery environment.  From year 1979 to 1980's, the invention of other Explosives like slurries and water gel Explosive were achieved to solve the problem of water resistance.

Many life's have been claimed by Explosive inventory from 1627 to 1980's.  

For the sake of people who are not associated with mining field. Blasting is done by drilling a hole, charging the hole with a specified Explosive quantity, connecting the blastholes with shock sensitive connecting cortex cords. After which shock wave from surface (cap and fuse for NONEL or exploder for electric) is release to initiate the downline Explosive primer and column charge.

The major challenge in 1969's was how to initiate the Explosive after loading it into the drill holes. The Explosive is highly sensitive, it detonates instantaneously, it requires specified shock energy to distinguished detonation from burning. 

Thou many approaches were used earlier but all were lacking high confidence in safety.

This call for the invention of Blasting accessories by Alfred Nobel in 1960's.

Although before then the Explosives have been worked on a bit to sensitize division into low and high Explosive. This brought about the classification of Explosive into those that are highly sensitive to impulse and those that are not. 

This classification was done base on the Velocity of detonation of each Explosive which dictates the gas pressure release at initiation. All this was done to ensure safety is garantee. 

After the incident that lead to the death of Nobel's brother during the invention of Nitroglycerin in 1840's, the idea of limiting the sensitivity of high VOD Explosive to specified shock energy and it distinct classification becomes interesting so as to aid SAFETY level at storage, usage and transportation. Most precautions attached to Explosive storage, transportation and handling were discovered through experiences that lead to lost of many innocent life. Let take a brief look at the classification breakdown and see the key elements that support the classification.

High and low Explosive: well I'm fully aware that this classification was done in a bit to ensure instant Explosion of Explosive material at drop, accidental throw is controlled. NG the killer Explosive during inventory left many scary experience like accidental drop during mixture, packing, transportation, storage which claim many life. Highly sensitive Explosive (primary Explosive rich chemicals) were not just sensitive to small shock but can accommodate and amplify small shock. The fact that at the encounter of primary Explosive with infinitesimal shock energy can produce magnified explosion makes inventors to call for a new way of ensuring safety. 

Differentiation between High and low Explosive

High Explosives are those with high Velocity of detonation, highly sensitive to shock energy or friction (undergo detonation), at destination release larhe amount of shock energy wave faster than the speed of sound (1200-9000 meters per second). This type of Explosive are known to be supply high detonation pressure than the low Explosive.

Prove:

Detonation pressure=(Explosive density*VOD^2)/4

Example of high Explosive are; Nitroglycerin, TNT, PETN.

Low Explosives are those with low VOD which at initiation with less shock undergo deflagration (burning) rather than detonation. Low Explosives are characterised by the release of only gas pressure at initiation. They released wave with speed lesser than the speed of sound (less than 2000 meters per second).

Example of low Explosive is ANFO, thou in most critical time, scholars tend to classify ANFO as blasting agent, but still is still year back to low Explosive.

Another thing that differentiate low and high Explosive is the ability of high Explosive to detonate under the shock wave supply by cap number 8 containing (0.125g lead azide and 0.78g PETN).

Blasting Accessories in view

These accessories are additional materials use along side with exploy to achieve blasting. The accessories are subordinate agents that create the required atmosphere needed for Explosive to function in the loop of explosion.

This was started by Alfred Nobel in 1960's after inventing his first Nitroglycerin dynamite. He make use of pan and black powder to create the first cap with the intention of creating means to have a safe distance between the time of initiation and detonation.

He invented safety fuse and cap for mining purpose in 1960's.

This tend to solve the issue of instantaneous detonation which limited the extent to which Explosive can be use for mining purpose. With this safety fuse and cap, large charged holes can be detonated at a safe time without the fire man appearance at the blast site.

The safety fuse recieve impulse from the fire person, take sufficient time to transmit the impulse to the cap which detonation (0.125-0.2g) of primary Explosive for the release of shock energy about 3200+ m/s to the primer and column charge through the detonating cord.

The invention of safety fuse, cap/detonator, connecting cords was a new phase of development in 1957-1970's.

Other blasting accessories use in blasting are: cortex cord, shock tube, surface delay, electric detonator, electronic detonator, exploder, clips, booster, to mention few.

My next article will cover safety Tips in Explosive handling, transportation, storage and usage.

You can access the video clip on my Facebook page (Mining Knowledge/Experience: GIANT MINER).

Mine the ore safely and interact with the earth safely as you explore you ore deposit for man benefit.

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Mine Dewatering Strategy: Reaching the Deposit at the face of Surface water

picture @Edo LGA in a Dolomite Quarry

Dewatering operation is one of the most sensitive and continuous operation during raining season.

The approach to this operation depends on the mine design, mining method and other factors including the mine terrain.

Most surface mine can not escape the challenge of surface water inflow but can be overcome through proper dewatering plan.

Dewatering is define as the process of removing unwanted collection of water in the mine. It describe as the approach use in remove water from mine pit so as to gain access to the ore deposit.

In view of surface Mining methods, which involves the extraction of deposit with less overburden thickness. The mining approach adopt in surface Mining methods are such that a cavity is advance into the Earth crust. Such cavity has lower attitude compare to the nearby environment which prompt the collection of water into it.

Mine out area (stope, pit) recieve water from:

1. Surface run-off water

2. Direct precipitation (Rain)

3. Underground water ( water below the mean sea level).

Surface water by hydrogeological survey is the water running along the dipping cause of earth crust whether from nearby river, stream, flood, or other surface appearance water.

Most times this can be water from abandoned pit  closer to the mine area or from gathered surface water.

As have earlier said, mine out area has lower elevation compare to it vicinity, this support the inflow of surface water into the mine.

Taking a sharp look at direct precipitation, surface mine is open directly to the sky, this makes it recieve water droplet during raining season.

Likewise in the view of underground water inflow, water gain access into the mine through fracture and cracks originated from blasting and geological Condition of rock.

Inflow can be from surface accumulation or from underground water.

DISADVANTAGES OF MINE WATER INCLUDES;

1. Stop in mine crude production
2. Damage to mine floor
3. Damage to mine wall and reduce wall strength and stability which can easily support wall failure
4. In the case of dimension block cutting mine, present of water can easily increase the aparture of cracks/fracture which will directly render most of the blocks not marketable
5. In case of rock/ore formation with compromise minerals grains, the dissolution of mineral grains under oxidation reaction may cause some of the grains internal force of attraction to reduce.
Most mineral grains may undergo weathering and leaching off due to acidic water reaction.
6. Ore formation containing sulphide mineral, radioactive minerals and other acidified mineral may likely result into acidic water formation. This becomes dangerous to equipment, plants among others. Pumping in such case become difficult and strategic.

CONTROL STRATEGY FOR MINE WATER.

Thou mine water accumulation is inevitable during raining season as we can't cover the mine cavity/stope/pit with water proof linens. Even if this is possible, can we stop aquifer water or underground inflow from entering the mine???

Since we just need to continue mine operation, below are some dewatering approach and method to reduce mine water challenge in the mine.

1. Use of pump and pump system: This involve the use of whether electric power pump or Diesel engine pump. The use of pump may appear not fully efficient in situation where the mine water inflow condition is continuous. But this is bypass by ensuring pump network is build and also drainage canal is constructed to fasten the flow rate of water in the mine environment. Is of no doubt that electric pump is fast pumping than the diesel pump, thou the challenge of cost and power system may hamper the use of this pump type.

2. Sump and pump system: sump is a hollow basin sunk somewhere around the mine for collecting water and to aid fast pumping.

This approach can be use to allow working access at one section of the mine while pumping is goin on at the other part of the mine.

3. Strategic mining approach: This is a tactical mining progress that involves varying elevation level of the production zone in the mine to avoid water infringement with mining work.

The mine design is such that it provides a working bench with little water inflow challenge.

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STEMMING OPERATION IN VIEW

Stemming in blasting is very important and affect not only the efficiency of the blasting but also the impact of the blasting on the environment.

By simple definition, stemming is a confinement process done by the use of innert materials to confine explosive charge within the drill hole during charging.

The define function of stemming is to:

1. Ensure the explosive charge is confine within the hole socket so as to avoid poor distribution of explosive release shock energy.

2. Prevent the escape of shock wave into the environment and causing airblast and other environmental impact.

Stemming can be top confine or inter-column charge confined.

In case of decking charge pattern, each explosive charge column is separated by innert material to reduce the charge weight and also to ensure effective distribution of shock energy along the hole column.

In the case of decking, stemming is use to confine and to separate upper charge column from the lower charge column.

Stemming materials can be the drill cuttings from the hole or poorly sorted, well-graded gravel or stones.

Use of stones of well-graded nature with particle size ranging from 4mm to 9mm tend to show good confinement than drill cuttings due to it heterogeneity nature that permit the grains interlocking.

Some of the factors that affects stemming length are:

1. Hole diameter

15-30D

2. Bench height/Hole depth

Stemming=0.45-0.55H

3. Burden

Stemming=0.7-1.5B

4. Explosive energy/strength: high strength explosive requires longer stemming length to confine and resist the escape of shock energy to the surface

5. Rock properties: This includes the rock strength, discontinuity nature among others.

Most cases, stemming may be position at point where discontinuity daylight on the hole wall instead of placing booster.

Also, stemming length varies with the strength of rock formation to be blasted.

Hard rocks like granite (>250Mpa) is blast with stemming length varying from 20-30D.

Medium rocks like dolomite:20-25D

Soft rock :15-20D.

Reason why stemming length tend to increase with Rock strength is that, stronger rocks offers higher resistance against the Penetration of released shock energy at detonation. The release wave tends to follow weaker zone instead of fracturing and slabbing the rock mass, in a bit to relieve the detonation pressure, the stemming of short length may be pull out.

This is why, lengthy stemming is needed to confine the Explosive energy within the rock mass.

In the process of selecting lengthy stemming the place of ensuring good and sufficient charge length must also be considered so as to enable good fragmentation.

Blasting with high safety condition, getting good blasting result alongside with good economic factor is what define a successful Blasting

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EXPLOSIVE ENERGY:THE CONCEPT OF BLASTING OPERATION IN MINING

Truly energy can neither be created not be destroyed but can change from one form to another. Explosive are chemical compound which at detonation releases specific joules of energy. The energy release during Blasting travels in form of shock  wave, heat energy, light energy, sound energy and gas energy. The first release is light energy followed by shock wave which is associated with heat energy.

The last release energy is the gas energy which finalize the work need to be done by Explosive charge.

Energy is defined by various scholars as the ability needs to do work. The work before Explosive during detonation is to explode rock mass, fragment rock mass, throw rock piles and to  cause other negative effects like ground vibration, airblast, and rock projection (flyrock)

Sequence of Explosive energy ULTILIZATION during Blasting

 The light energy travels faster than all others energy, it shows the initiation direction of Explosive charge detonation. 

Check this about light energy

Thou the charges are initiated by shock energy.

Checking most slow play rock Blasting videos we see first the sequence lightning which is been followed by the shock waves then sound energy.

By the reason of definition, high Explosives are those capable of detonating under the shock energy produce by cap number 8 to release shock energy faster than the speed of sound.

Shock energy perform diver functions among which include ignition of the base charge and column Explosive charge.

The shock wave from the detonator initiate the primer and detonate the Explosive column. The shock wave in a view of achieving the fragmentation work requires from Explosive, it create radial cracks into the rock mass within the design burden and spacing.

The micro-cracks are created under compression and tensile slabbing. This prepare the rock for explosion.

Rock By definition (dipping towards Bowel series reaction: The pit of temperature influence during magma grains growth)

Rocks are by definition the aggregate of many minerals. Each available rock on Earth can be categories into basically three classes;

1. Igneous rocks,

2. Sedimentary rocks, and

3. metamorphic rocks 

1. igneous rock (also called the primary rocks): is formed generally by the cooling and solidification of molten magma flowing through volcano vent from the magma chamber located legendly in the mantle. Examples are basalt (apharitic texture rocks known to be volcanic igneous rock due to it surface eruption and rapid cooling rate), granite (the most abundant rock on Earth, usually phaneritic in texture composing dominantly mica, feldspar and Quartz. Other types are pegmatite, gabbro, obsidian and pumice.

Flashing l Other rock classification 

2. sedimentary rock: formed by the reaction of diagenesis process (compaction and lithification) on deposited rock sediments. Usually deposited in beds/strata in obedient to superposition principle. Examples includes; sandstone, limestone, clay, shale among others.

3. metamorphic rocks: This class of rocks are formed by the occurrence of metamorphosis process on pre-existing rocks. This process involve the change in rock form under the influence of high temperature and pressure. Example includes; gneiss, marble, Dolomite, quartzite, schist among others.

 I choose not to dig deep in this rock of a thing so I don't end up talking for hours on rocks. Rocks are my textbook anyway we need to learn a bit about them.

I was trying to register the idea of heat functionality in rock breakage during Blasting before I was been tossed into the stope and winze of rock classification.

What I was about doing is to explain the concept of bowel series reaction which form the basic foundation for mineral formation during magma cooling.

The idea of heat energy is that, upon Explosive charge detonation, The heat energy weakens the rock Mineral grains bond. It cooks most of the rock minerals to the point of recrystallization which enables the creation of radial micro cracks by shock wave during tensile slabbing. Thou the process of heat transfer during explosion occurs very rapid. The heat cook up the grains  and create path of weakness for the waves to travel compressively and tensionally.

I keep picturing this idea in my mind untill I come to understand it during the process of breaking rocks using sledge hammer. The  small scale miners  and artisan miners (SSM & AM) call this operation knocking process. Thou it not included in mining process sequence (Drilling, Blasting, mucking, loading and haulage).

 I also read history on past old age mining approach, the miner in a bit to break rock boulders cook up the boulders with fire so as to cause particulate and grain expansion. The boulders are heated beyond the thermal spallability strength of the rock, just to enables it fracturing during hammering.

Also, in the place of thermal drilling process where by oxygen and fuel oil is burn below the drill bit  so as to cook up the rock for fast Penetration of drill bit during grinding, crushing of the rock by the bit cones/tooth.

Heat release during Explosive charge detonation aid the easy cracking and slabbing of the rock.

I will stop here about that for now.

To the gas energy, it function is to fill the created cracks and due to its high pressure nature causes explosion of slabbed and unstable rock mass.The gas energy perform the explosion and the throw of rock pile.The reason for proper Blast design is to ensure this Explosive release energies are use positively.

Some of the control factors include the powder factor, bur

The burden and spacing, the rock characteristics (uncontrollable factors), Explosive proper selection among other factors.

Thanks for reading.

If you gain anything try to comment this phase:

 "Explosive is for peace and not for war, for making money and not for terrorism" 

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ACHIEVING A GOOD BLASTING:POST AND PRE BLASTING INSPECTION IS THE KEY

Pre Blasting and post Blasting inspection for data collection and blast design is very important so as to performance a profitable and productive Blasting.

Some of the pre-blasting inspection carried out before Blasting includes;

1. Ground water condition (in-hole water check)

2. Rock face discontinuity mapping

3. Drilling parameters collection.

4. Free face checking.

1. Ground water condition (in hole water)

Water may be present in the mine either through surface inflow or underground water outflow.

Ground water condition affects Blasting materials, expecially when using a non water resistant Explosive like ANFO. This may result into MISFIRE and poor fragmentation.

All holes must be inspected and those with water should be noted.

Water tend to reduce the sensitivity of non water resistant Explosive. Explosive like Dynogel and emulsion gel and other water resistant Explosive should be use in noted water filled holes.

Hole with water can also be drained or flush by high pressurized air before charging.

2. Discontinuity mapping

Mostly in mine face and floor fractures occur due to overbreak induced by the previous Blasting. Some cracks in rock may be of wide aparture capable of stealing grain Blasting Agents and concentrating it at a point ( this may result into formation of flyrocks if the concentrated/trapped Explosive is close to the free face where burden is less).

Thou fractures may tend to appear in rock due to natural phenomenon like weathering and stress relief. The discontinuity condition of rock mass need to be checked before drilling and possibly after drilling to contain it effect on Blasting.

3. About drilling parameters, this is very important as poor drilling design will totally affect Blasting. Some of this design parameters are burden and spacing, hole Depth and hole diameter.

Imperfect hole parameters affect not only burden movement during Blasting but also affect Blasting cost, environmental safety and Blasting result.

Poor hole burden distribution affects burden movement during Blasting which tends to create the production of unwanted Blasting result. The concept of Achieving good Blasting, we need to ensure our drilling design is properly done and if possible checked on softwares like O-pit blast for outlier drill holes.

Most mining companies complain of blast overbreak and poor fragmentation. The damage created by Blasting shock waves can be contained by proper drilling design which help to optimumly ultilize Explosive energies during detonation.

Checking Bench or mine free face provided by the drilling team is also an important thing to consider during Blasting. This will help to control charge density rate at the first hole row to prevent the possibility of flyrock and other Blasting created hazard.

Some of the post-blasting inspection includes; Misfire checking, wall and roof scaling, Blasting fume and gas testing, fragmentation checking and analysis.

Get the complete detailed post-blast explanation later.

Thanks.

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MINING AT PROFIT: BLASTING SAFETY AS A KEY

The main aim of mining is to secure profit.

This in most cases may be affected by mine operation cost if not properly managed.

Drilling and Blasting plays high role in ensuring profit in Mineral exploitation.

If the expenses incur on drilling and Blasting yield poor result, it tends to affect all the downstream operation cost.

It therefore good that blast design be done and monitored thoroughly by the Mine supervisor.

This is liken to safety in the mine, workers life is very important and must be given principal consideration.

Blasting must be done safely with no accident record or any form of misfire.

Explosive is dangerous when poorly handle but peaceful if well handled.

In 1960s before Alfred Nobel light up Explosive works, the use of Nitroglycerin Explosive base, TNT and puliminating Mercury & gold had cause great havoc due to there high sensitivity.

But for the discovery of Ammonium Nitrate base Explosive which are less sensitive but high exotically sensitive.

Explosive is now design to detonate under the availability of Shock wave from highly sensitive detonator and other Blasting accessories.

Conclusively;

Mine profitability is a function of;

1. Good Safety management System

2. Good mine operation system (development, drilling, Blasting, excavation, haulage & transportation)

The three key safety elements are very important to ensure mine safety.

These keys are:

1. Engineering

2. Education

3. Enforcement

Engineering safety element: This comes in the place of Engineering design, quality assurance and quantity assurance. Bench design work, mine design, blast design and other Engineering related min aspect must be given high priority.

2. Education safety element: All workers must be education on mine state view, wall stability, equipment usage and handling. Knowledge is safety: knowledge of mine operation and equipments goes a long way to remain safe in the mine.

3. Enforcement element: All safety rules, regulation, law, policy must be enforce on mine workers

EXPLOSIVE AND BLASTING DESIGN AND SAFETY MEASURE: TECHNOLOGY FOR SAFE ROCK BLAST AND EFFICIENT USE OF EXPLOSIVE

Blasting Design, safety and Explosive handling and Storage: Many scholar contribution worldwide

[07/06, 8:33 p.m.] Hanif Ullah khan: The purpose of a good open pit blast design (production blast) is to achieve the following at acceptable costs...:

-fragmentation, muckpile profile for safe and efficient loading and hauling and other downstream processee

-wall stability

-minimum environmental impacts (undesirable effects of a blast): ground vibrations, noise, airblast, _flyrock_, dust and fumes.

[07/06, 8:33 p.m.] Hanif Ullah khan: I will be throwing in some of the rules of thumb for open pit blast design. A rule of thumb is basically a principle with broad application that is not intended to be strictly accurate but can be quite handy in coming up with sound and economic designs

[07/06, 8:33 p.m.] Hanif Ullah khan: -Mining equipment: equipment also has a say in the blast deasign process. Drilling equipment dictates blasthole diameter and depth limits. Loading and hauling equipment control the required fragmentation and muckpile profile.

[07/06, 8:33 p.m.] Hanif Ullah khan: Groundwater causes desensitisation of non water resistant explosives hence poor blast results. Water also increases the chances of borehole collapse and breakage.

[07/06, 8:33 p.m.] Hanif Ullah khan: *BLAST DESIGN CONSIDERATIONS*

[07/06, 8:33 p.m.] Hanif Ullah khan: -Rock type: blast design has to be rock type based taking into consideration rock mass properties for optimum blast results. E.g. technical powder factor is assigned to various rock tyoes for basing on the blasting category whether hard or medium or soft. Rock types in the hard category have a technical powder factor between 0.7 to 0.9 kg/m3 such as granite or dolerite. Medium category rocks have 0.40-0.45 kg/m3 such as dolomite or quartzite. Soft category rocks 0.25-0.35 kg/m3 eg sandstone or limestone. There are very soft rocks/minerals such as coal which have 0.15-0.25 kg/m3

[07/06, 8:33 p.m.] Hanif Ullah khan: -Groundwater: presence of groundwater dictates the use of water resistant explosives which are a bit expensive such as emulsions, slurries or water gels. Water may also force the use of borehole liners or impermeable sleeves with the non water resistant explosive such as ANFO/ANFEX/ANBA

[07/06, 8:33 p.m.] Hanif Ullah khan: Other rock properties include density/sg, young’s modulus (elasticity), ultimate compressive strength (ucs) and ultimate tensile strenght (uts)

[07/06, 8:33 p.m.] Hanif Ullah khan: -Blasting concerns: there may be sensitive structures, features or activities in the vicinity of the blasting area which may call for the blast design to carefully cater for the control of the environmental effects of blasting e.g tailings dam maybe affected by ground vibrations, powerlines, people in built up area maybe affected by flyrock airblast and noise etc

[07/06, 8:33 p.m.] Hanif Ullah khan: -Bench height: the bench height should be safe and economic to mine. 10-18m benches are the most common. If the bench height is too high, a high unsafe muckpile results, blasthole deviation becomes more defined and it becomes difficult and dangerous to scale/barr down bad hangings. Bench height should be matched to blasthole diameter. For reasonable blasthole utilisation and efficient explosive action, the explosive column should occupy at least half of the blasthole length and hence the total blasthole length should be at least 50 hole diameters although in most applications the normal range applied is 60-140 hole diameters.

[07/06, 8:33 p.m.] Hanif Ullah khan: As a rule of thumb: burden must be about 25 to 35 times the hole diameter..

[07/06, 8:33 p.m.] Hanif Ullah khan: Coming up with a a blast geometry is the most fundamental step in blast designing

[07/06, 8:33 p.m.] Hanif Ullah khan: Exactly..Thanks for clarifying. Eg if hole diameter is 115mn then the total blasthole must be 6900mm to 16100mm

[07/06, 8:33 p.m.] Hanif Ullah khan: *BLAST DESIGN FACTORS/ASPECTS*

[07/06, 8:33 p.m.] Hanif Ullah khan: -The presence of free faces: these enable the explosives energy to perform the greatest amount of work on the rock mass. As far as is practicable the free faces must face away from areas of concern to minimise projectiles and flyrock to the area. Where there is no free face a box cut is used to open up the ground

[07/06, 8:33 p.m.] Hanif Ullah khan: -Burden: correct burden ensures optimum fragmentation. If it is too small it causes premature venting of explosion gases, airblast and flyrock. Too large a burden causes poor fragmentation, flyrock and noise from the toe and crest regions, wall instability after blast, poor muckpile looseness and diggability ana also ground vibrations

[07/06, 8:33 p.m.] Hanif Ullah khan: -Spacing: it should be in the range 1.0 to 1.5 times the burden. 1.0 gives a square pattern as the burden will be equal to the spacing and is suitable fot small bench blasts, and gives efficient drilling and easy connecting up

[07/06, 8:33 p.m.] Hanif Ullah khan: Thanks for giving us the rules of thumb they make blast design easier

[07/06, 8:33 p.m.] Hanif Ullah khan: Spacing which is 1.15 times the burden gives a staggered pattern which has the advantage of better explosives distribution and hence better fragmentation

[07/06, 8:33 p.m.] Hanif Ullah khan: As a rule of thumb: spacing should not be more than half the depth of the borehole...

[07/06, 8:33 p.m.] Hanif Ullah khan: -Explosive charge distribution: this is a function of charge length, stemming length and subdrill

[07/06, 8:33 p.m.] Hanif Ullah khan: -Blasthole diameter: large diameter holes have the following advantages:- they are fewer to drill, suitable for high benches with cheap bulk explosive, fewer initiation units (detonators and primers), and more volume of rock is broken by a single blasthole. Smaller diameter holes give better explosives distribution in yhe rock mass hence better fragmentation, less oversize material and less environmental effects. As diameter of blasthole increases, a subsequent increase in powder is required to maintain optimum fragmentation

[07/06, 8:33 p.m.] Hanif Ullah khan: -Blasthole angle: blastholes inclined in the the direction of the free face ensure better uniformity of burden from toe to crest (ideally the blasthole should be parallel to the free face). Correct blasthole angle addresses toes, stumps and floor conditions whilst controlling overbreak, noise airblast and flyrock. Angled holes also ensure better throw and muckpile looseness.

[07/06, 8:33 p.m.] Hanif Ullah khan: As a rule of thumb: the subdrill can be estimated to be in the range of 8-12 times the hole diameter or 0.2-0.5 times the burden.

[07/06, 8:33 p.m.] Hanif Ullah khan: *sub drill:- the main purpose of subdrill is to control floor and toe conditions. It also allows for the fall back of drill cuttings and sludge since flushing the hole is not 💯 effective. In some cases the subdrill may not be necessary and may actually be backfilled eg if a prominent geological interface exists such as blasting a coal seam

[07/06, 8:33 p.m.] Hanif Ullah khan: *charge length: also a function of linear charge density (kg/m) which is primarily controlled by the explosive density. Charge length must be greater 20 times the hole diameter

[07/06, 8:33 p.m.] Hanif Ullah khan: Charge length= hole length - stemming length

[07/06, 8:33 p.m.] Hanif Ullah khan: Stemming shorter than 20 times hole diameter usually leads to excessive noise, airblast, flyrock and overbreak.

[07/06, 8:33 p.m.] Hanif Ullah khan: -Bench height = stemming length + charge length. Total charge length = charge length + subdrill. Stiffness ratio (bench height/burden) is also another check to the blast design:- it must range from 3-4 for good control of undesirable effects and for optimum fragmentatio.

[07/06, 8:33 p.m.] Hanif Ullah khan: 👍👍

The main purpose of subdrill is to provide good pit floor level.

It not necessary in strata or layered deposit as they tend to produce smooth floor.

Such as coal as the presenter had mentioned

[07/06, 8:33 p.m.] Hanif Ullah khan: *Stemming: inert material that fills up the remainder of the blast hole to the collar. It serves to confine the explosion and contain the detonation gases. Stemming controls fragmantation and displacement, airblast, noise and flyrock. Drill cuttings are usually used as stemming material but but crushed rock aggregate gives better and more effective stemming. The crushed rock size should be 10% of the blasthole diameter. Care should be taken during charging as the drill cuttings tend to contaminate the exllosive. Stemming length should be 0.7 - 1.2 times the burden. As a rule of thumb: stemming length should be 30 - 40 times the hole diameter if drill cuttings are used and 20 - 30 times hole diameter if crushed rock is used. generally it can also range from 20 to 60 times the hole diameter depending on geology and rock properties

[07/06, 8:33 p.m.] Hanif Ullah khan: -Blast timing: blast results depend on interaction of blastholes of blastholes- the sequence in which blastholes are initiated and the time interval between successive detonations. Bkastholes must be detonated in a controlled sequence with proper delays to achieve the desired blast result

[07/06, 8:33 p.m.] Hanif Ullah khan: -Geology: discontinuities, bedding plane partings, joints are the main geological factors. Absence of joints imply that more explosive energy will be required to fragment the rock. Joints can cause fragmentation to be course or fine depending on joint spacing. Joints cause venting of gases leading to air blast, flyrock, irregular face walls, increased risk of overbreak, instability and cutting off of adjacent blastholes.

[07/06, 8:33 p.m.] Hanif Ullah khan: Timing dictates the muckpile profile which is a function of the requirements of the loading equipment e.g a shovel works best on a high muckpile whilst a dragline works best on a flat muckpile

[07/06, 8:33 p.m.] Hanif Ullah khan: Let's solve an example. How to calculate specific charge.

How to calculate powder factor.

How to calculate specific drilling.

How to calculate explosive required for Blasting

[07/06, 8:33 p.m.] Hanif Ullah khan: I will like to make contribution to the bench height selection.

Majorly bench height selection depends on three factor during open pit mine design.

These factors are;

1. The ore dilution control

2. Loading equipment boom height

3. Geological factor as in Discontinuity/slope failure & stability

[07/06, 8:33 p.m.] Hanif Ullah khan: *At the end of the day a blast design must spell out the following:*

- ```blast geometry- burden, spacing, stemming, charge length, subdrill

- powder factor

-drilling patter and blasthole layout

-initiation design```

[11/06, 2:25 p.m.] Taiwo Mining Eng: Great kamran👍👍.

The important of decking includes

[11/06, 2:26 p.m.] Taiwo Mining Eng: I. Reduce the amount of Explosive use per charge

[11/06, 2:28 p.m.] Taiwo Mining Eng: 2.it a blast control techniques, as in air decking.

[11/06, 2:30 p.m.] Taiwo Mining Eng: 3. It also aid efficient distribution of Explosive shock wave per charge length

Here's my contribution on the Transportation of Explosives. 

The vehicle carrying explosives should:

1) Run on at least 4 wheels

2) Be in a serviceable condition

3) Be rubber lined

4) If it's an open truck then it should be covered with tarpaulin to cover explosives.

5) Should travel at a speed not exceeding 50km/hr

6) Should have a sprug chain which will be constantly in contact with the ground. 

7) Should have serviced fire extinguishers. 

8) Should also have red flags indicating it's carrying explosives. 

Explosives can only be transported during daytime, between sunrise and sunset.

Fly rock and its control 

[03/07, 10:03 p.m.] Taiwo Mining Eng: By definition,

Flyrocks are pieces of rock ejected from the blast site during Blasting as a result of the u control execution of Explosive energy

[03/07, 10:04 p.m.] Taiwo Mining Eng: Flyrock as a verb, is the unwanted projection of rock piece from a blast site during Blasting.

Which is prompt to cause damage to nearby building, machine, mine workers to mention few

[03/07, 10:06 p.m.] Taiwo Mining Eng: Flyrock can be classified into three base on the projectile direction.

[03/07, 10:06 p.m.] +27 79 654 6330: Stemming is very important to control flyrock aswell as P F

[03/07, 10:07 p.m.] Taiwo Mining Eng: 1. Catering flyrock: rock moving in any direction from top of the blast face

[03/07, 10:07 p.m.] Taiwo Mining Eng: 2. Face blast: rock moves in front direction

[03/07, 10:08 p.m.] +27 79 654 6330: Burden and spacing also very important

[03/07, 10:08 p.m.] Taiwo Mining Eng: 3. Rifting: rock moves upward from blast face

[03/07, 10:11 p.m.] Taiwo Mining Eng: The following are the causes of flyrock during Blasting,

1. Poor o inadequate stemming

2. Faulty blast design

3.misfire

4. Poor firing sequence

Just to mention few

[03/07, 10:15 p.m.] Taiwo Mining Eng: How does poor or inadequate stemming causes flyrock production?

Mostly, poor stemming length or stemming material result in put out of hole.

Upon Explosive initiation, the generated energy, gas energy and shock wave tend to search for weak zone as it support it ease movement.

I adequate stemming causes Explosive energy to throw out from the blast top, this result in the projection of rock particles.

[03/07, 10:17 p.m.] Taiwo Mining Eng: To misfire,

For the causes of this presentation, I will define misfire as the Explosive left unfired during Blasting.

[03/07, 10:20 p.m.] Taiwo Mining Eng: In view of this definition,

During Blasting, each hole rows have specific burden to fragment.

Meaning, each hole has a specified rock volume to break.

Having some unblaster hole or hole row affects the efficient work of other holes

[03/07, 10:22 p.m.] Taiwo Mining Eng: The usage of Explosive energy distribution depends on the quantity of work load on each hole.

If the rock to be broken by a hole row is to large, the Explosive energy tends to put out on blast top.

[03/07, 10:28 p.m.] Taiwo Mining Eng: Firstly,

Faulty blast design can be in different factor:

1. Poor burden and spacing selection

2. Use of large powder factor

3. Bad design in related to pit slope angle and the first hole row

[03/07, 10:28 p.m.] Taiwo Mining Eng: Starting with poor burden and spacing

[03/07, 10:30 p.m.] Taiwo Mining Eng: Small burden, causes large release of energy after rock slabbing.

At, Explosive detonation point shock wave are released first to create cracks, the follow by gas energy

[03/07, 10:33 p.m.] Taiwo Mining Eng: If the burden use is small compare to the powder factor use, the rock mass cracking occur nearly simultaneously with the gas energy release.

This cause more of the shock energy to project the rock far away from the blast site.

Despite the production of finer rock particles,

The unused energy throw the rocks farer distance

[03/07, 10:34 p.m.] Taiwo Mining Eng: Large powder factor release excess energy beyond that require for cracking, other unused energy is create air wave and surface wave which project rock far from the blast site

[03/07, 10:35 p.m.] Taiwo Mining Eng: Bad design in related to pit slope angle and first hole row.

[03/07, 10:43 p.m.] Taiwo Mining Eng: This start from,

1. Proper blast design: in place of good burden selection,good powder factor or specific charge.

2.drilling: driller should observe the variation in the drilling speed. This will help to discover if there is weak zone in the rock so as to put this into consideration during blast design

[03/07, 10:45 p.m.] Taiwo Mining Eng: 3.Geology of the blast area: present of mud seams (coal), natural joints, fracture or cavities.

This must be give proper consideration to during blast design

[03/07, 10:46 p.m.] Taiwo Mining Eng: 4. Explosive loading up: while charging in watery holes, sufficient care has to be taken to prevent misfire.

Also,explost selection must be done in view of the mine site condition

[03/07, 10:50 p.m.] Taiwo Mining Eng: Other means of controlling flyrock includes:

1. Muffling or Covering: This involve using blast mat, chain to cover the blast during Blasting.

This can also be done by the use of sand.

The blast after charging and connecting/chaining, is covered with sand to prevent rock projection

Explosives storage and transportation.....

[25/06, 8:52 p.m.] Taiwo Mining Eng: Blasting licence is granted to company fireman under the operation of a competent mining Engineer.

The Blasting license is to be renewed annually

[25/06, 8:58 p.m.] +263 77 502 0991: What is FISH????

[25/06, 8:58 p.m.] +263 77 502 0991: These are the four sources of Ignition

[25/06, 8:59 p.m.] +263 77 502 0991: When an explosives is subjected to any of these four they are high chances of an explosion

[25/06, 9:00 p.m.] +263 77 502 0991: FISH so that you dont forget

[25/06, 9:00 p.m.] +263 77 502 0991: F stands for Friction

[25/06, 9:01 p.m.] +263 77 502 0991: when an explosive material is su bjected to friction it will explode eg a bucket of your LHD lashing and explosives are on the ground especially your sensitive products such as detonators they will explode

[25/06, 9:01 p.m.] +263 77 502 0991: I stands for Impact

[25/06, 9:02 p.m.] +263 77 502 0991: a boulder falls on to your explosive the next thing is an explosion

[25/06, 9:04 p.m.] +263 77 502 0991: your static electricity eg your lightning

[25/06, 9:04 p.m.] +263 77 502 0991: The reason why we put chains on vehicles conveying explosives

[25/06, 9:04 p.m.] +263 77 502 0991: H stands for HEat

[25/06, 9:05 p.m.] +263 77 502 0991: Heat will cause your explosives to explode

[25/06, 9:05 p.m.] +263 77 502 0991: Remember Friction Impact Static and Heat these are your sources of ignition

[25/06, 9:06 p.m.] +263 77 102 8782: As explained by Moshen, the explosives are stored in a Magazine that is licenced under the Explosives Regulations. There are 2 types of Magazines namely Immovable and portable Magazines. There are specifications that are supposed to be met in the construction of the magazine that includes the provision of ventilation flues, lining the interior with non ferrous material and provision of an earthen mount around the magazine.

[25/06, 9:06 p.m.] +263 77 102 8782: The Magazine Master also displays his official appointment in the magazine.

[25/06, 9:06 p.m.] +263 77 102 8782: Also to be included in the Magazines are the permits and licences for storage which stipulates the type and quantities that can be stored in that particular magazine.

[25/06, 9:06 p.m.] +263 77 102 8782: The Magazines are located away from populated areas and away from public infrastructure. The regulations also stipulate the respective minimum distances depending on the size or capacity of the Magazines.

[25/06, 9:10 p.m.] +263 77 102 8782: Remember the closer you are to an explosion the less noise you will hear

[25/06, 9:12 p.m.] +263 77 502 0991: Also the law stipulate the type of material that you use for the construction of the magazine

[25/06, 9:13 p.m.] +263 77 502 0991: here in Zim for your immrovable magazine you use steel reinforced concrete at least 150mm for the wall floor and roof

[25/06, 9:14 p.m.] +263 77 502 0991: for your portable magazine the steel plate must be at least 5mm

[25/06, 9:20 p.m.] Taiwo Mining Eng: Here for the portable magazines steel plate of 5-6mm is use to construct a container. With temperature regulated linears

[25/06, 9:21 p.m.] +263 77 502 0991: The temperature inside the magazine must not exceed 35 degreees

[25/06, 9:21 p.m.] Taiwo Mining Eng: For the immovable, a special build is usually use.

Thou I haven't been to any before but.

I learn about it from Engineers.

[25/06, 9:24 p.m.] Taiwo Mining Eng: Also,

Old Explosive are used first before the new Explosive

[25/06, 9:30 p.m.] +27 79 654 6330: Adhere to speed limit S A 80 km/h

[25/06, 9:33 p.m.] Taiwo Mining Eng: All vane wired part/connection must be properly insulated

[25/06, 9:33 p.m.] +263 77 505 6630: Yes it's possible though not advisable. You just have to make sure the ox drawn cart travels at walking speed.

[25/06, 9:36 p.m.] +27 79 654 6330: Detonators and pakaged explosives seperatly

Misfire: 

[25/07, 10:04 p.m.] +591 72391160: The second point is that we must be aware of what kind of misfire we are facing...

[25/07, 10:06 p.m.] +591 72391160: As in the presentation we have three main factors for misfere to occur...

[25/07, 10:08 p.m.] +591 72391160: So we as leaders must identify what happened. And the best thing is always to identify the root cause...

[25/07, 10:08 p.m.] +263 77 109 9677: *In Zimbabwe this is how we legally define a misfire*

A “misfire” in relation to a charge of explosives means a charge which has failed to explode either wholly 

or in part;

[25/07, 10:21 p.m.] +91 88775 55835: *MISFIRE* it's means Detonator failed to explode the explosive charged within the Hole. MISFIRE is a Very Dangerous for miner's who involved in Blasting section.

[25/07, 10:23 p.m.] +263 77 109 9677: *Based on these definition, From Experince,*

Misfires are caused by.

1. Faulty blasting cables

2. Bad timing sequencies eg causing cutoffs

3. Leaving some explosives column(s) from the firing connection.

4. Faulty blast initiators, eg. Bad or faulty detonators, safestarts, shirstarters.

5. Poor explosives combinition eg.6D detonators and non cap sensitive explosives.

6. Bad safety fuse capping

* Although rearly*

1. Bad product:

2. Wrong cut positioning and burning front issues

[25/07, 10:26 p.m.] +91 88775 55835: It is totally waste of time and money so as good engineer we must having good Knowledge as well as practical experience about MISFIRE. 

As a good mining engineer we must know about MISFIRE-

1) How to deal with misfire.

2) what type of precautions should be taken.

3) Know the actual place of MISFIRE Shots

[25/07, 10:28 p.m.] +27 79 543 2075: The best way to deal with a misfired hole is to drill a relieving hole 2m apart from the misfired hole and re-blast it

[25/07, 10:29 p.m.] +91 88775 55835: MISFIRE occurred due to-

Bad quality of explosive

Defective Detonator

Broken detonator lead

Damaged Exploder

[25/07, 10:30 p.m.] +91 88775 55835: Wrong connection

[25/07, 10:30 p.m.] +27 79 543 2075: To add on that when personnel stops thinking or when rushing and through ignorance

[25/07, 10:37 p.m.] +91 88775 55835: What Precautions should be taken after Hole goes to misfired

1) the cable should be checked before Blasting

2) Exploder should be examined at every 3 months by competent person 

3)only good quality of explosive and detonator shall be used 

4)it is better to having two single core cable for shotfiring with maintained distance.

5)the circuit should be tested for continuity by a Galveno meter

[25/07, 10:43 p.m.] +91 88775 55835: How to deal with misfired-

1)all the entrance to the face should be fenced 

2) No person should enter at the site of blasting after 30 minutes

3) Another reliving Hole shall be made at the distance of 30 cm 

4) after fired a reliving Hole defective Detonator and explosive cartridge shall be searched in Blasted ore and take out to the surface for know the Reason.

[25/07, 10:44 p.m.] Taiwo Mining Eng: Thanks to the two presentery

[25/07, 10:44 p.m.] Taiwo Mining Eng: Presenters*

[25/07, 10:44 p.m.] Taiwo Mining Eng: I will be starting mine now

[25/07, 10:45 p.m.] Taiwo Mining Eng: They have said slot, so I will not repeat there areas.

But give detail explanation on some

[25/07, 10:45 p.m.] Taiwo Mining Eng: If you are following say

Following...

[25/07, 10:47 p.m.] Taiwo Mining Eng: Adding to all mention definitions,

Misfire is the complete or partial failure of a Blasting charge to detonate/explode as planned.

[25/07, 10:49 p.m.] Taiwo Mining Eng: I want us to know this that,

Misfire is not limited to charge failure at initiation, but also extend to accidental detonation of Explosive and other Blasting accessories

[25/07, 10:50 p.m.] Taiwo Mining Eng: Since misfire I very hazardous, every reasonable means available to site manager must be taken to avoid it occurrence

[25/07, 10:50 p.m.] Taiwo Mining Eng: I will be taking about,

How to recognize misfire

[25/07, 10:52 p.m.] Taiwo Mining Eng: After firing, a proper checking of face and muckpile must be done to ensure that there is no indication of misfire

[25/07, 10:52 p.m.] Taiwo Mining Eng: The occurrence of misfire during Blasting result into the following blast challenges:

[25/07, 10:53 p.m.] Taiwo Mining Eng: 1. Production of Noxious fumes and toxic dust

[25/07, 10:53 p.m.] Taiwo Mining Eng: 2. Inadequate ground movement

[25/07, 10:53 p.m.] Taiwo Mining Eng: 3. Poor fragmentation

[25/07, 10:53 p.m.] Taiwo Mining Eng: 4. Unusual blast sounds or vibration rate

[25/07, 10:53 p.m.] Taiwo Mining Eng: 5. Flyrock

[25/07, 10:54 p.m.] Taiwo Mining Eng: 6. Evidence of undetonated Explosive in bench face or in muckpile

[25/07, 10:54 p.m.] Taiwo Mining Eng: This 6 Condition is what was a Blasting Engineer can use during blast to at least predict if there is misfire or not

[25/07, 10:55 p.m.] Taiwo Mining Eng: The occurrence o misfire (now during Blasting) is not dangerous but the post blast effect is the main problem

[25/07, 10:56 p.m.] Taiwo Mining Eng: How can this 6 sign occur and why does it occurred?

[25/07, 10:57 p.m.] Taiwo Mining Eng: Production of Noxious fumes and toxic gases is as a result of alteration in the Explosive oxygen balance due to incomplete detonation

[25/07, 10:58 p.m.] Taiwo Mining Eng: As we all know, oxygen balance is very important.

It dictate the type of gas, time and dust produce from Explosive at detonation

[25/07, 11:01 p.m.] Taiwo Mining Eng: Each Explosive has been tested at production and all gases reacting with oxygen had been balance in such a way that, at detonation, only those gases that are not poisonous are released.

Incomplete or partial detonation of Explosive led to negative oxygen balance.

This final cause the complete production of Noxious fumes which is hazardous

[25/07, 11:03 p.m.] Taiwo Mining Eng: As a Blasting expertise, we should know Blasting 100 charge holes will generate more ground movement than 70 charge holes.

As the load density will be different

[25/07, 11:04 p.m.] Taiwo Mining Eng: Also, poor fragmentation result from misfire

[25/07, 11:06 p.m.] Taiwo Mining Eng: During Blasting, failure of two or more holes affect burden movement.

It create more oversize and poor fragmentation.

[25/07, 11:06 p.m.] Taiwo Mining Eng: We have talk about this in our past WEBINAR, so I won't be talking more on it 

If you want more.

Message me privately

[25/07, 11:07 p.m.] Taiwo Mining Eng: What are the post Blasting misfire inspection

[25/07, 11:07 p.m.] Taiwo Mining Eng: Inspection of misfire after Blasting is a dangerous task

[25/07, 11:08 p.m.] Taiwo Mining Eng: In all circumstances must be done in accordance with site rules

[25/07, 11:09 p.m.] Taiwo Mining Eng: Hazard exist not only from the remaining undetonated Explosive but also from the post blast environment

[25/07, 11:11 p.m.] Taiwo Mining Eng: It is possible that misfire Explosive to detonate after some time, therefore it is essential that adequate trained personel who regularly check the muckpile and face during loading operation

[25/07, 11:13 p.m.] Taiwo Mining Eng: Unchecked misfire is very dangerous, as when load and transport to the processing plant can detonate during crushing.

We study the four initiation stimuli from @⁨Moshy⁩ presentation.

FISH: Friction, impact, shock and heat

[25/07, 11:14 p.m.] Taiwo Mining Eng: Impact during crushing can initiate undetonated Explosive in Boulder socket.

[25/07, 11:15 p.m.] Taiwo Mining Eng: The extent and nature of misfire must be determined

[25/07, 11:15 p.m.] Taiwo Mining Eng: As soon as possible after the misfire ha be defected

[25/07, 11:16 p.m.] Taiwo Mining Eng: After check and clear: The *All Clear* sign should be given.

But if not yet clear the dangerous zone must be barecade

[25/07, 11:16 p.m.] Taiwo Mining Eng: Barricade*

[25/07, 11:17 p.m.] Taiwo Mining Eng: *How to deal with misfire*

[25/07, 11:18 p.m.] Taiwo Mining Eng: Now after we have done our post Blasting inspection and confirm the occurrence of misfire

[25/07, 11:18 p.m.] Taiwo Mining Eng: These are some ways to deal with the misfire

[25/07, 11:19 p.m.] +27 79 707 2601: You report n barricade so tht u can do re blast

[25/07, 11:19 p.m.] Taiwo Mining Eng: 1. Removing stemming and re-priming

[25/07, 11:20 p.m.] Taiwo Mining Eng: These are some precautions to observe when doing this

[25/07, 11:20 p.m.] Taiwo Mining Eng: 1. When the detonator is close to the undetonated Explosive, stemming removing with force should not be attempt

[25/07, 11:22 p.m.] Taiwo Mining Eng: 2.In case of electric detonator the use of high velocity air should not be attempted as it can generate static charges sufficient to initiate electric detonator

[25/07, 11:23 p.m.] +234 806 562 9334: In a situation where the down the hole has been cut by blasted rock, let's say you have five charge holes that misfire. What did you sugest

[25/07, 11:26 p.m.] Taiwo Mining Eng: 3. Bulk Explosive can be washed out if misfired shotholes.

But special care must be taken in removing the cartridge expecially where detonators are involved

[25/07, 11:27 p.m.] Taiwo Mining Eng: 5. Under no circumstances must Explosives or detonator be removed from a drill hole by pulling on the detonating cord or detonator lead

[25/07, 11:28 p.m.] Taiwo Mining Eng: 6. Use suitable extracting tools if required

[25/07, 11:28 p.m.] Taiwo Mining Eng: Soon of the advantage of using high pressure water to flush Explosive during misfire

[25/07, 11:30 p.m.] Taiwo Mining Eng: 1. It desensitise any non water proof Explosive and dissolve high concentration of water soluble Explosive ingredients

[25/07, 11:30 p.m.] Taiwo Mining Eng: 2. It overcome the mechanical lock of stemming material comprising chippings

[25/07, 11:31 p.m.] Taiwo Mining Eng: Other way of dealing with misfire is by

*Drilling and firing relieving holes