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
