Regulation Part 8 - Explosives

Question 1

The regulations specify that precautions must be taken when drilling in an underground mine. What are those actions that a person must not do?

Answer 1

• A person must not drill in the floor, wall, backs or face of any development, stope, shaft or bench until the area to be drilled has been washed down & inspected for misfires. A floor, bench or shaft bottom may be blown with compressed air & water for inspection.
• Must not drill within 15cm of the edge of a butt, a shattered area of the burn is considered a butt.
• A person must not drill in any face containing a charged hole or misfire unless instructed by an authorised person, and for misfires, after a certain time period after firing as instructed by an authorised person.

Question 2

What do the regulations require in regard to a person using a pneumatic loader to load bulk AN-based explosive into a hole?

Answer 2

• A person must not use a pneumatic loader to load bulk AN explosive unless the loader, charging hose, earthing arrangements are safe, efficient & in accordance to manufacturers specifications.
• The explosive must be loaded through a semi-conductive hose or tube having resistance:
  > 15,000 ohms/m
  < 2 mega ohms across total length

Question 3

(a) What do the regulations require with regard to the suspension of work when a misfire is suspected to have occurred in an underground mine?
(b) What do the Regulations require with regard to the suspension of work in surface mining operations if a misfire is suspected to have occurred?

Answer 3

(a) A person who suspects or confirms a misfire must:
- Report it to the Underground Manager, Foreman or Supervisor
- If misfire occurred at end of shift, report to the relieving person

A person must not drill into a face with a misfire until the misfire has been made safe or rectified.

(b) If a misfire is suspected to have occurred, no work may be done at the location until the Mine Manager, Quarry Manager or authorised person has inspected the site & have taken such action as is necessary to ensure further work may be continued.

Question 4

(a) What do the Regulations require with regard to fly rock in surface mining operations?

Answer 4

• If debris from blasting constitutes a danger, precautions are taken as are necessary to prevent injury to persons and damage to property.
• If fly rock can land on public roads or property, ensure blasting mats are used & secured in a manner which will contain the debris.
• If the nature / extent of blasting makes blasting mats not effective, the manager must ensure the blast design (stemming, charge length, delay) are such to minimise fly rock.

Question 5

The manager of the mine must ensure that any underground explosives magazine meets a number of requirements.

List these requirements.

Answer 5

The Mine Manager must ensure that an Underground Magazine is:

• Located as far as practicable from any shaft / access, substation, pump station, primary fan or other important installation.
• Located and constructed so as to mitigate and minimise the effect of fumes to persons workplaces due to accidental ignition / fire.
• Constructed only after a thorough inspection of boreholes that may intersect with the magazine and have been plugged sufficiently with grout.
• Adequately ventilated.
• Located and constructed so that every precaution has been taken to minimise the risk of a fire in the mine.

Question 6

What is required by the regulations regarding ‘Drilling precautions’ in surface mining operations?

Answer 6

• A person must not drill in any face or bench until it has been examined for misfires.
• A person must not drill such that any portion of the drill hole is closer than 6m to a hole containing explosive except:
  
  • When clearing a misfire after repriming and refiring.
  • Approved by the Quarry Manager in writing, subject to precautions being taken
• If approval is given to redrill a hole adjacent to holes already charged, precautions must be taken, including the protection of initiating systems at the collars of the charged holes.

Question 7

What is required by Regulations regarding:

(a) Storage of detonators?
(b) Smoking near explosives?
(c) Dealing with explosives on mine closure?

Answer 7

(a) - Detonators are stored in a magazine that is seperate from the magazine in which explosives are stored.
- No detonator is stored in an Underground Magazine unless it is contained & separated from any explosive in the magazine so that any exploded detonator will not detonate the explosive.

(b) A person must not smoke or use any naked light within 8m of any explosive or initiating system.
(c) Old & deteriorated explosives are not stored in a magazine and are removed & destroyed.

Question 8

What is the responsibility of:

(a) Each responsible person regarding application of Dangerous Goods Safety Act 2004, as it applies to explosives.
(b) Manager regarding faulty explosives in a magazine?
(c) Manager regarding explosives on closure of a mine?

Answer 8

(a) Each responsible person must ensure that the manufacturer, storage, transport, supply, use and disposal of any explosive is in accordance with the Dangerous Goods Safety Act 2004.
(b) The Mine Manager must ensure that old or deteriorated explosives are not stored in a magazine and if found, must be removed and destroyed.
(c) If the mine or any part of the mine is closed, that the explosives stored there are removed and disposed of according to manufacturers recommendations.

Question 9

The regulations provide that a blast plan for the use of an explosive must be in writing and include matters required by AS2187.2 Appendix 2 section A2 as the circumstances require.

List any 10 of the 33 matters that should be included as content of a blast plan.

Answer 9

1. Location of proposed blasting.
2. Description of proposed blasting.
3. Shotfirers details.
4. Blast layout plan including drilling pattern and hole depths.
5. Detonation sequence / effective charge mass per delay.
6. Type of explosive used and quantity required.
7. Method of initiation.
8. Type of firing equipment and procedures.
9. Proposed dates and times of firing.
10. Details of the exclusion zone.

Question 10

What do regulations require regarding firing warnings underground?

Answer 10

A person intending to fire in an underground mine must:

• Give a complete and definite warning to all persons in adjacent workings before the person fires.
• Ensure that all means of entry to the place of firing are guarded against entry and firing warning notices are erected.
• Ensure any warning notices are removed when work in that place has resumed.

All persons must be removed to the ventilation intake side of the mine where resultant fumes and dust will not affect them.