Principle of Control Blasting 1: Presplitting blast Techniques Theory

Open pit mining is one of the surface mining method use in exploiting less overburden material. Open pit method is one of the special mining method use to extract competent ore with flat shape.

This method is unique with it's step wise approach use to mine the deposit in benches.

The safety requirements for the success of this type of mine is not restricted to 

Open pit blasting at first may require box cut approach to create additional free face at the horizontal direction for successful throw.

Mostly if the blasting is carried out at the last bench floor or as the first blasting for face opening.

In such case where:

1. Environmental Impact has to be controlled,

2. Safety of workers, equipment and nearby things have to be presented,

3. Blast economy in place of cost of blasting material effect on overall blasting cost have to be minimize,

4. Success optimum fragmentation size with less than 5% oversize and undersize, and

5. Dilution, overbreak and back break needs to be prevented for high safety and low downstream operation cost sake...

The use of control blasting tends to be very crucial and must be practice in all mine site.

Control blasting is a special Blasting approach that involves strategic control of Explosive energy to avoid damaging intert rock wall and to avoid environmental impact of blasting.

Control blasting techniques include;

1.Presplitting technique, 

2.smooth blasting, 

3.cushion blasting,

4. line drill hole, 

5.post splitting,

 6.Air decking among many others. All control blasting techniques try to achieve the same aim but through different objective.

To control the rate of shock energy, gas energy, radial cracks, flyrock, ground vibration, airblast released during blasting.

But optimizing powder factor, drill and blast design parameters.Thou rock heterogeneity and anisotropic nature makes control blasting design varies from formation to formation.Most civil engineering construction blast involved control blasting to avoid overbreak of wall and floor. Some of the reasons why control blasting is needed:

1. To avoid overbreak: this is creation of discontinuity by the shock energy beyond the bench width during charge detonation.

2. To avoid reduction in support wall strength and competency: fracturing of support wall and toe reduce the stability of slope which prompt rock to easily fall under load redistribution during excavation.

3. To prevent high ground vibration, flyrock, airblast and other environmental Impact 

 4. To control blasting cost through charge weight reduction and still achieve optimum fragmentation

5. To control dilution rate in grade variation formation.

For civil engineering works, control blasting techniques are use to fragment road obstructing rocks (outcrops) during tunneling, building foundation laying and road construction.

This idea is to ensure the hindring rock is break down with competent and smooth face at LHS AND RHS.

Now to presplitting blasting technique after understanding reason why we need control blasting in mining and petroleum (casing perforation at production zone) in civil engineering.

Presplitting is one of the control Blasting techniques use to ensure good Explosive-rock interaction during Blasting. It involves splitting the production zone from the supporting rock block (unblast rock wall). This techniques is differ from post-splitting by the initiation timing as the one detonate production hole first why another detonate perimeter hole First. Presplitting had been practice earlier before the use of Explosive in construction.

In Egypt and other countries, the use of wedge wood and fire heat had be ultilize to split rock mass, likewise in Northern locations spallation effect of freezer water is used. Drill holes are filled with water, as the water frozen it expand and split rock mass.

This traditional approach was used before 1950's. The first presplitting blast wast done in Lewiston power plant as part of Niagera powder project. This was a project involve the blast of dolomite & limestone formation with shale bed.  Many Presplitting method was applied including line hole drilling with three hole step charging, cushion blasting before presplitting was use with dynamite cartridge. The are various type of presplitting:

Traditional, precision and many others but all still in the optimize of Explosive load, stemming and spacing parameters.

From different scholars (Joseph Konya, cook, beckee-kietiakowsky) point of view, Explosive released energy theory were studied to ensure good control during presplitting blast. For the shock wave release, various theory like; Livingston cratering theory, Bureau of mines catering theory, shockwave spallation theory and strain wave theory among others were propanded and infused to ensure the control of micro-fracturing rate during presplitting.

And for the gas energy study for precision splitting, the following equation of state was propanded to calculate the explosion pressure released from charge at detonation; Beckee-kistiakowsky-wilson (BKW) equation of state, Cook's equation of state, Taylor's equation of state, Outoyne-Skidmore-Konya (OSK) equation of state and many more. Learning on the shock and gas energy generation rate during detonation gives the scholar great confidence to give precise and accurate approach to presplitting blast and other Control blasting techniques. If the capacity and energetic strength of each Explosive charge is understand, to control it damage rate becomes easy and accurate.

Presplitting Blast design Parameters

Presplitting make use of the following approach in order to ensure proper Explosive energy;

1. Explosive load weight: blast energy both shock and gas energy increases with exolosive load. During presplitting blast charge, decoupling of peripheral (control holes )to reduce the charge density. Decoupling is the use of small diameter Explosive cartridge in large diameter hole. The decoupling ratio is the ratio of the the Explosive cartridge diameter to the drill hole diameter. Decoupling reduce Explosive energy by creating air allowance between Explosive cartridge and rock wall, therefore the release wave interact with air (having low Sonic velocity) before interacting with the rock mass. In a bit to contain the Explosive energy within the cut line, Explosive load weight is calculated using various design rule of thumb formula including;

Dcc=(Dh^2)/28

Where;

DCC is the charge weight in pounds,

She is the Explosive cartridge diameter.

Also Joseph Konya propose presplitting Konya constant to model Explosive load weight,

K=(40579/E)^0.625

EL=7000*(S/K)^2

Where;

K is the Konya presplitting constant,

E is the rock Young modulus,

EL is the Explosive load weight.

S is the spacing

2. Spacing: spacing is the distance between two adjacent holes in thesame row. Providing wide and optimum space between hole controls the volume of rock block to be fragment by each energy release from each kilogram of edplosive. Increase in spacing reduce the efficiency of hoop stress distribution amongs the holes detonated. The spacing between presplitting holes increase the resistance offer by the rock mass against the release Explosive energy.

Some rule of thumb formula use for spacing during presplitting blast include;

S=10Dh

3. Stemming length: stemming according to konya have no effect on Explosive shock wave but affect the explosion pressure. Well confined holes generate high explosion energy, this will avoid flyrock and also support good throw and backbreak.

4. Initiation timing sequence: Initiation timing of blast charge simple explains the detonation pattern follow by each of the hole during firing. In order for presplitting blast to prevent overbreak at the design boundary between the production block and the supporting rock wall,the peripheral holes (The hole at the production and support wall boundary) are decoupled and initiated first ahead of the production holes. This is where the name Presplitting comes from. The peripheral holes split apart the production section of the ore deposit, creating a free face between the two rock block. This split point avoid further fracturing during production hole Blasting.

Summarize Theory of presplitting blast

The whole idea is to divide the drill hole into two sections.

1. Production holes: holes to be blasted for Run-off- mine crude production Or the holes place in the rich grade zone during dilution control or the hole arranged on the rock mass to be broken away from highway.

2. Peripheral holes or the control holes: These are hole placed at the boundary of the blast rock and supporting wall.

The hole powder factor or load weight is controlled base on the rock strength and the Explosive strength.

Also the hole design is done using specified rule of thumb formula.

The initiation system use in presplitting is design such that the initiating signal reach the peripheral holes first before the production holes. This is achieve through the use of delay detonators (which can be surface delay or down-The-Hole delay). In this case, the charge in peripheral holes are detonated before the production holes charge. The peripheral holes charge is light and decoupled, this ensure perfect splitting and detachment of production block from the insitu rock with smooth face. As soon as the energy from the production hole gets to the split point it's escape to the surface vertically.

Some of the special blasting accessories use for presplitting blast include: delay detonator, decoupling sleeves among others.

Watch and subscribe to my YouTube channel by clicking here...

presplitting Blast Video

presplitting Blast techniques Explanation video

Thanks for reading and commenting.

To get notify of the article when I release it, kindly subscribe to my blog page 

Like my Facebook page @ mining Knowledge/Experience: Giant Miner, subscribe to my YouTube channel @Taiwo Blessing olamide

 a lot and I hope you gain one or two things. Feel free to ask me questions 

WhatsApp@+2347031018600

email@taiwoblessing199@gmail.com

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.

WhatsApp contact: +2347031018600, for any questions and consultant

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.

Check/follow my page on Facebook @Mini g Experience/Knowledge: Giant Miner.

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

®Mining Experience/Knowledge: Giant Miner

Follow my page on Facebook @Mining Experience/Knowledge: Giant Miner

Check out my Mining video on development

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" 

##Giant_Miner

WhatsApp contact:+2347031018600

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.

GIANT MINER.

WhatsApp number:+2347031018600

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