Workbook 7 - Blasting Safety

Introduction

Safety is always our first concern. However, to have a safe operation requires the cooperation of all persons involved. The good working practices discussed in this workbook should become a part of your daily routine. If you put these practices to work for you, you'll help make your operation a safer place to work.

Preliminary Questions

General Safety

The safety of (all people/the workers - which?) _______________ should be foremost in everyone's minds as they perform their duties.
The purpose of this program is to (CHECK THE CORRECT ANSWER):
- A. Mention only a few safety rules to give you an idea of how to develop your own safety habits
- B. Touch on the major safety elements and encourage the practices which will help develop safer working habits
- C. Cover every rule and regulation, which will help develop safer working conditions
Most of the commercial explosives consumed in this country are used in a variety of surface operations.
- A. True
- B. False
You should be careful around boreholes (CHECK THE CORRECT ANSWER):
- A. Because some of them are actually large enough for a person to fall into, and some of them are very deep
- B. But none of them are large enough to fall into
- C. But none of them are very deep, so rescue would be very easy

Answers - Page 1

All people
B is correct
A is correct
A is correct

Magazine Storage

What is a magazine?

Answer: _______________
A magazine is for storage; therefore, anything from combustible materials to blasting agents, explosives and detonating caps and cords can be stored in the same magazine.
- A. True
- B. False
In a magazine, boxes should be stacked (CHECK THE CORRECT ANSWER):
- A. Not more than six feet high
- B. With two inches of air space between the wall and the boxes
- C. Close together and as high as possible to make as much room for storage as possible
- D. Both A and B are correct
All magazines should be opened and inspected (CHECK THE CORRECT ANSWER):
- A. Every day
- B. Every third day
- C. Weekly
The danger signs at a magazine should be (CHECK THE CORRECT ANSWER):
- A. Posted directly on the magazine
- B. Posted above the door, so that anyone entering will be able to see them
- C. Located so that a bullet passing in the direction of the sign will not hit the magazine
All magazines must be heated to prevent anything from becoming damp and worthless.
- A. True
- B. False

Answers - Magazine Storage

A magazine is any building or structure approved for the storage of explosive materials. (OR SIMILAR ANSWER)
B is correct
D is correct
B is correct
C is correct
B is correct

Transportation

Any vehicle used for the transportation of explosives should have (non-sparking/padded - which?) _______________ floors.
Placards should be posted on (two sides/all four sides - which?) _______________ of a truck carrying explosives material.
All vehicles used for transportation of explosives are required to carry one fire extinguisher.
- A. True
- B. False
Detonators and other explosive materials may (CHECK THE CORRECT ANSWER):
- A. Never be transported in the same vehicle
- B. Be transported in the same compartments
- C. Be transported together provided they are separated by ___ inches of hardwood lining or the equivalent
It is important that detonators and all other explosives be transported (CHECK THE CORRECT ANSWER):
- A. As soon as possible after loading
- B. Within a week after loading
When a vehicle carrying explosives must be parked, it is only logical that (CHECK THE CORRECT ANSWER):
- A. The brakes be set
- B. The engine be shut off
- C. It be blocked securely to prevent rolling
- D. All of the above are correct
Vehicles, while loaded, shall not be (CHECK THE CORRECT ANSWER):
- A. Moved from one area to another
- B. Driven near a blasting site
- C. Taken to a garage for repair

Answers - Transportation

Non-sparking
All four sides
B is correct - at least 2 fire extinguishers are required
C is correct (4 inches)
A is correct
D is correct
C is correct

Theft and Vandalism

Prevention

Good safety practices will help to increase your _______________ and decrease the possibility of _______________.

Another element to consider when dealing with explosives is the prevention of theft and vandalism. Recent studies have shown that needless accidents and injuries have resulted from unauthorized persons gaining access to explosive materials.

The theft or unauthorized possession of explosives (is/is not - which?) _______________ a violation of federal law.

Not only are theft and vandalism federal crimes, explosives used incorrectly can involve innocent people, sometimes even children. Each year children are injured or killed by blasting caps they find, or even steal.

All explosive materials should be kept locked up to prevent _______________ and _______________.

Summary

Explosives and explosive materials should be kept in a manner that will:

A. Prevent _______________ and _______________
B. Eliminate the possibility of blasting caps and other such items being found by _______________ and used as toys
C. Avoid criminal action, since unauthorized possession of explosives is a _______________ offense

Prevention Methods

An example of preventing unauthorized possession is to (CHECK THE CORRECT ANSWER):

A. Keep all magazines locked securely
B. Keep all entrances to the mine properly guarded to prohibit unauthorized entry
C. Move all explosive materials back to the main storage unit at the end of your shift

Detonating Cord

Handling Precautions

You should always handle detonating cord in the same manner as you would other explosive products. Some people have the impression that detonating cord itself will not explode.

You should be careful not to damage or sever the cord before using it: this could result in misfires or premature detonation.

Detonating cord (can/cannot - which?) _______________ be considered a potential hazard.

Loading Procedure

When using detonating cord for a blast, always cut the line extending into the borehole before loading the rest of the charge.

Handling detonating cord also includes making good connections in accordance with manufacturer's recommendations. Knot-type or other cord-to-cord connections should only be used with _______________ cord.

Damaged Cord

Detonating cord that has been bent or kinked should not be used. Such imperfections may interrupt the train of detonation.

This interruption may cause a _______________.

Connecting Caps and Delays

Electric blasting caps and delays should not be connected to the detonating cord until everything else is ready for the blast.

Attaching these devices in advance may result in _______________.

EB caps and/or delays should be connected to the detonating cord by methods recommended by the manufacturer. The caps should always be pointed in the direction that the cord is to detonate.

The direction of the initiation is assured by the (CHECK THE CORRECT ANSWER):

A. Type of cord used
B. Type of cap used
C. Direction the cap is pointed

Summary - Detonating Cord

When using detonating cord, you should:

A. Check for kinks or sharp bends to avoid _______________
B. Attach caps and delays to the detonating cord just prior to the blast time to prevent _______________
C. Make sure the cap is pointed (toward/away from - which?) _______________ the direction of detonation

Electric Blasting Caps

Testing

When blasting with electrical blasting caps, you should always test the circuit with the appropriate blasting instrument designed specifically for this purpose.

These tests should be performed:

Prior to connecting
As a complete series circuit after hook-up

Except when being tested, electric detonators, wired rounds and blasting lines should be kept shunted until immediately before the blast.

These shunts help prevent premature _______________.

Brand Consistency

Electric blasting caps of different styles or functions, or made by different manufacturers, should not be mixed.

If different types of caps were wired into the same circuit (CHECK THE CORRECT ANSWER):

A. All of the caps would still detonate properly
B. All of the caps may not detonate as desired
C. The entire blasting circuit would fail

Power Line Safety

Make sure that the firing line and the blasting cap wires are so short that they cannot reach overhead power lines.

If these wires should be thrown across overhead power lines, an accident (could/could not - which?) _______________ occur - someone could be electrocuted.

Records show that over the years several shotfirers have been injured or killed by this type of short-circuiting.

It's important for safety reasons that firing lines and blasting cap wires be so _______________ that they cannot reach the power lines.

Stray Current

The firing circuit should be completely insulated from the ground and other conductors such as bare wires, rails, pipes or other potential paths of stray current.

It is a known fact that _______________ can cause premature detonation.

Electrical Storms

Some types of stray electrical current can detonate electric blasting caps.

When an electrical storm is approaching the blasting site (CHECK THE CORRECT ANSWER):

A. Work can continue as long as extra precautions are taken
B. Continue working until the storm has reached the blast area
C. All personnel should be evacuated from the blast area to a safe position

Non-Electric Delay Systems

Stray Current Immunity

Many mining operations prefer to use a non-electric delay system. As the name suggests, this type of system (is/is not - which?) _______________ affected by stray electrical current.

Impact Sensitivity

Even though non-electric delay systems or ms connectors have improved safety features, the explosive charges are similar to those in blasting caps and can be detonated by impact.

Precautions should be taken to protect ms connectors from (CHECK ANY CORRECT ANSWERS):

A. Accidental impact such as falling rocks or other heavy objects
B. Dropping or rough handling
C. Contact of hand tools

Even though the explosive charges are similar to blasting caps, ms connectors (must/need not - which?) _______________ be protected from flame, excessive heat and sparks.

Special Primers

Blasting agents such as ANFO and the insensitive explosives require special primers to ensure dependable performance. These primers are generally characterized by:

High strength
High velocity
High density
Combined to give high detonation pressures

The primers used for ANFO, water gels and other non-cap sensitive products are usually pressed or cast mixtures consisting basically of explosive ingredients. For the most part, they are designed to be detonated by either blasting caps or detonating cord.

However, the insensitive explosives require (the same/less - which?) _______________ care in handling as the more sensitive explosives.

Safety of Combined Systems

These special primers are classified as explosives because they are both cap sensitive and contain an explosive ingredient, and should be treated as explosives.

However, the special primers are almost as insensitive to shock and friction as the blasting agents.

The combination of these primers with blasting agents or low-sensitivity explosives represents (CHECK THE CORRECT ANSWER):

A. The most hazardous blasting system used
B. The safest blasting system presently available
C. A very impractical way to blast

Blasting Procedures

Cartridge Loading

With the boreholes in proper condition and the primers correctly made up, the loading and firing procedures should proceed normally.

Loading cartridge explosives in which the wrappers have been removed (increases/decreases - which?) _______________ the potential hazards of reducing water resistance and the release of toxic gases after the explosion.

Crew Size and Organization

The loading of holes should be done by as few people as possible. The work should proceed in an orderly manner with drills and other equipment removed from the blasting area.

All extra explosives should be returned to their storage area, and all empty cases and other debris removed.

It (is/is not - which?) _______________ essential that the minimum number of people be exposed to the blasting operation.

Following the Blasting Plan

The blasting plan, including the drilling procedures and selection of explosives, has been done well in advance of the loading of the holes by experienced personnel.

By carefully following this blasting plan you will help (CHECK ANY CORRECT ANSWERS):

A. Prevent injury to personnel
B. Avoid damage to equipment
C. Obtain desired blasting results

Proper Stemming

Proper stemming is important to the overall blasting operation. Crushed rock is ideal stemming material, but usually the drill cuttings near the hole are adequate if holes are dry.

Proper stemming:

A. Helps provide (maximum/minimum - which?) _______________ blasting efficiency
B. Increases the element of _______________ for all blasting personnel

Tamping

In angling or horizontal holes where the stemming must be packed in tubes or regular tamping bags, a tamping pole will be used to insert the stemming into the hole.

Logically, the cord or wires (should/should not - which?) _______________ be held tightly along the side of the hole to avoid _______________ during the tamping of the stemming.

The tamping poles should be made of wood or other suitable non-sparking material. The type of material used in the construction of the tamping poles will assure that no sparks are produced which could _______________ the explosives.

Firing

Pre-Blast Precautions

Before a blast, several precautions must be observed:

The entire area must be cleared of personnel and equipment
A signal system should be arranged to notify all persons in the danger zone

Guards should block all access roads to the blast area (CHECK THE CORRECT ANSWER):

A. Before any work is started at the blasting site
B. Just after the blast, before anyone returns to the work area
C. Just prior to the blast

Destroying Explosives

Boxes and Packing Materials

All empty explosives boxes, box liners, sawdust, empty bags and cartridges should be collected and destroyed partially because they are a potential hazard and partially because animals may eat the paper products which (could/could not - which?) _______________ be fatal.

Burning is the most satisfactory method for the destruction of such boxes and packing materials. There is always that possibility of an explosion during the burning process because:

The materials have absorbed some of the liquid explosive, or
There may still be some explosive(s) present

Therefore, the burning must take place at a location such that injury or damage will not occur in the event of an explosion.

Immediately after the fire is started, all persons involved should go to a safe place.

Waste Materials

Waste materials that have accumulated while loading the shots should be burned, preferably after the shots have been made.

If they are burned before the shots, the burning should (always/never - which?) _______________ be performed in shot area, or (before/after - which?) _______________ the holes have been stemmed.

Detonators

When to Destroy

Detonators such as non-electric blasting caps, electric blasting caps, and delays should be destroyed if they show any sign of deterioration.

These devices should also be destroyed if they have ever been under water, even if they have been dried out.

Sometimes the shells of the caps will show signs of corrosion if they were wet and then dried. These caps (may/may not - which?) _______________ be dangerous to handle.

Destruction Method

The method used most often to destroy detonators is to explode them with dynamite or a primer under some confinement.

Destroy each type of detonator according to the manufacturers' recommendations.

Never throw detonators into small lakes or bodies of water, such as rivers, creeks, ponds or water-filled abandoned quarries as a method of destruction.

Destroying ANFO

Water Destruction

Ammonium nitrate/fuel oil mixtures can be destroyed by putting them into water.

Water pollution must always be considered from both ammonium nitrate and oil.

Water used to destroy ANFO must be disposed of (CHECK THE CORRECT ANSWER):

A. By dumping it into the nearest stream or pond
B. In a manner which prevents pollution
C. By spreading over the ground

Burning

If ANFO is to be destroyed by burning, follow the manufacturers' recommendations. These represent the safest way to destroy any explosives.

Shot Guarding and Signals

Preparation for Blast

In preparation for a blast, three important precautions must be observed:

All access to the blast area should be prevented
Adequate cover must be provided for personnel and equipment
A positive warning system must be used before the blast is fired

To prevent accidental entry into the blast area, all entry points must be _______________ prior to the blast.

Warning Signals

The signal to fire the blast should be given by the person in charge. The signal should only be given after he is sure that all personnel and equipment are in a safe place.

Some effective warning signals could be to (CHECK THE CORRECT ANSWER):

A. Sound a horn or siren
B. Have one worker whistle
C. Shoot a flare into the air

Summary - Three Precautions

The three important precautions that must be taken when preparing for a blast are:

A. Access roads should be adequately _______________ to prevent accidental entry
B. All personnel and equipment should be _______________
C. A positive _______________ should be employed before the blast is fired

All-Clear Signal

After the shot has been fired, the area cleared of smoke and checked for misfires, the all-clear signal should sound.

This signal should indicate that it (is/is not - which?) _______________ safe for the workers to return to the blasting area.

Flyrock Hazards

Shelter Requirements

Recent studies indicate that flyrock is a constant hazard and has injured many people.

Even the best blasts and the most careful controls cannot completely eliminate the possibility of flyrock.

The only complete safeguard for personnel is shelter. Special flyrock shelters are an excellent idea.

If these special shelters aren't available, the blasting area must be completely _______________.

Public Roads

When blasting near public roads, which are within flyrock range, extra precautions must be taken.

Sometimes this (does/does not - which?) _______________ require halting the traffic during the blasts.

Misfires

Prevention

By following the recommendations for transporting, storing, handling, loading, and firing explosives, the failure of a charge to explode will be a rare occurrence.

However, misfires can happen to any blaster and are caused by a wide variety of reasons.

All misfires are potential hazards and every precaution should be taken to help prevent them.

Guidelines for Misfired Holes

All misfires should be reported to the proper supervisor and disposed of safely before any other work is performed in that area.

The area must be guarded, and an investigation made to determine the amount and extent of misfired explosives.

The investigation must be made by (CHECK THE CORRECT ANSWER):

A. Any blaster who is available at that time
B. A qualified person
C. Blasting supervisor

Dynamite vs Blasting Agents

A misfired charge of dynamite is extremely hazardous and must be handled only by a person who is thoroughly experienced in the handling of _______________.

While a misfire of blasting agents and detonating cord is serious, the problems such materials pose are (more/less - which?) _______________ hazardous than those of misfired dynamite.

Muck Pile Misfires

In surface blasting, misfired explosives are often thrown into the muck piles by the force of the blast from other holes.

In this situation, all visible explosives should be (CHECK THE CORRECT ANSWER):

A. Buried deeper into the muck pile
B. Disposed of safely to prevent detonation
C. Left as they are

Disposal Methods

The discovery of a misfired hole containing the balance of the explosive charge requires special handling:

A. Bulk ANFO can be washed out and desensitized with _______________
B. Other charges can normally be reprimed, properly covered and _______________

Prevention Through Procedures

Misfires are usually the result of careless practices or the failure to follow recommended practices for the handling of explosives.

Close adherence to proven procedures will greatly reduce the frequency and severity of _______________.

Truck Breakdowns

Unloading Requirement

Loaded explosives trucks should not be taken to a garage for repairs.

When a truck loaded with explosives breaks down and it's necessary to take it to the garage, the first step is to _______________ the truck.

Cleaning

Some particles of explosives might remain in the truck's cargo area, even after it's unloaded.

Therefore, you should use water to wash out the truck to make sure any remaining explosives are removed.

To be sure everyone's safe, a loaded explosives truck should be:

A. First, _______________
B. Then _______________ out thoroughly before it's taken to the garage

Repair Hazards

Perhaps the small amount of explosives that might remain in an unloaded explosives truck would cause no problem.

On the other hand, if certain procedures (welding, for example) were necessary in the repair process, an explosion could occur - and someone could be hurt.

Before even an empty explosives truck (or any type of hauler used to transport explosives) is taken to your garage for repair, be sure it's _______________.

Auger Cleaning

Bulk ANFO trucks are sometimes equipped with augers which help move the blasting agent out of the truck. These augers occasionally need repair - and that repair work may involve welding.

When this is the case, the auger must be thoroughly cleaned first, because small amounts of _______________ may be imbedded in cracks or pits in the auger surfaces.

Unless these surfaces are washed down, an _______________ hazard could exist.

Summary

The majority of explosives accidents can be prevented. The objective behind this module is to present common-sense judgments which will help to make your job safer.

In all situations, you must follow the Federal and Provincial laws and regulations and Company and local policies which govern your mine.

Test - Workbook 7: Blasting Safety

Instructions: Select the correct answer for each question.

1. Safety should be a primary consideration in a blasting operation, and this includes the safety of:

A. All people on mine property
B. People travelling, working or living outside the permit area
C. Both A and B are correct

2. A magazine is:

A. Any building or structure approved for the storage of explosive materials
B. Any building you decide to use for storing explosive material
C. Always a box-type structure that can be moved onto the blast site

3. An inhabited building is any building:

A. Used as a place of human habitation
B. Such as a school, church, store, etc., where people are likely to be
C. Both A and B are correct

4. Magazines must be posted with danger signs:

A. On all four sides, so anyone approaching will be able to see them
B. Located so that a bullet passing in the direction of the sign will not hit the magazine
C. Only when near inhabited areas

5. For the safety of the explosives, and anyone dealing with explosives, the magazine must be:

A. Bullet-proof and fire-resistant
B. Weather-resistant
C. Both A and B are correct

6. The inside of the magazines should be:

A. Kept clean and free of debris
B. Ventilated to prevent the explosive materials from becoming damp
C. Both A and B are correct

7. In a magazine, the explosive materials should be stacked:

A. Away from the wall and not more than four feet high
B. Not more than six feet high, with two inches of air space between the wall and the boxes
C. Against the wall, but not more than six feet high

8. When a vehicle carrying explosives is parked:

A. The brakes must be set, the engine shut off, and wheels blocked
B. The engine can be left running
C. It need not be blocked - the parking brake will hold

9. One of the best ways to prevent unauthorized possession of explosive materials is to:

A. Keep all entrances to the mine property guarded to prevent unauthorized entry
B. Take all explosive materials back to the main storage unit at the end of your shift
C. Keep all magazines locked securely

10. When using detonating cord, you should:

A. Be sure the cap is pointed away from the point of detonation
B. Make sure the cap is pointed toward the point of detonation
C. Always point caps downward, into the ground

11. If different types of caps are wired into the same circuit:

A. The entire blasting circuit will fail
B. All of the caps will detonate properly
C. All of the caps may not detonate as desired

12. The firing circuit should be completely insulated to:

A. Prevent stray current, which could cause premature detonation
B. Help keep the circuit warm
C. Prevent electrical shock hazards

13. By following the blasting plan carefully you will help:

A. Obtain the desired blasting results
B. Prevent injury to personnel and damage to equipment
C. Both A and B are correct

14. Proper stemming:

A. Does nothing to increase the safety element for all blasting personnel
B. Helps provide maximum blasting efficiency
C. Is not a major safety concern

15. Poles used for tamping should be made of:

A. Non-sparking material
B. Metal
C. Wood, and nothing else

16. Roads leading to the blast area should be blocked:

A. Just prior to the blast
B. Before anyone returns to the work area, after the blast
C. Permanently, while drilling and blasting operations are being conducted

17. Explosive materials which show signs of deterioration must be:

A. Used immediately, before they deteriorate beyond use
B. Stored in the back of the magazine, so they are not used
C. Disposed of properly or returned to the manufacturer for disposal

18. An effective warning signal often used to indicate that a blast is about to occur is to:

A. Sound a horn or siren
B. Shoot a flare into the air
C. Announce the blast on a public address system

19. The all-clear signal is sounded to inform the workers that:

A. The blast has been fired and the smoke has cleared
B. It is clear to fire the blast
C. The blast has been fired, the smoke cleared and the area checked for misfires

20. Sometimes misfired explosives are thrown into the muck pile by the force of the blast from other holes. These misfires should be:

A. Left alone
B. Disposed of to prevent detonation
C. Picked up and re-used

Answer Key - Test

Question	Answer
1	C
2	A
3	C
4	B
5	C
6	C
7	B
8	A
9	C
10	B
11	C
12	A
13	C
14	B
15	A
16	A
17	C
18	A
19	C
20	B

Fill-in-the-Blank Answer Key