Would Prep Seals that Contained and Controlled 7Nth Longwall Spontaneous Combustion Event Have Saved North Goonyella in 2018, and 104 LW at Grosvenor in 2020?
In all of the MRE from September 2018 that we have reviewed so far, I cannot recall any mention of Prep Seals being in place, or any preparations to enable an Emergency Sealing of 9 Nth Longwall Block as an Alternative if Inertisation did not control the heating, by either the Inspectors or Mine Management.
From what records we do have, it appears that the deciding factor about why Inertisation efforts finally succeeded in 2014, was the fact that it was quickly Emergency Sealed as workers withdrew to the Surface.
Prep Seals are not a new and novel concept.
It was in the Coal Mining Act 1925 (as amended) Underground Rules 4.6 (d) on page 100.
(d) ensure that before pillar or other block extraction in any district is commenced, preparations for the rapid erection of a seal in each entrance to that district have been completed. Such preparation shall consist of the installation and supply of all necessary materials so that seals that are, as near as practicable, air-tight may be erected in all such entrances within a period not exceeding three hours.
This provision did not survive to the 2001 Coal Mining Safety and Health Regulation.
This matter was the cause of considerable debate with the Chief Inspector at the time Brian Lyne.
The Mining Company argued loud and long for its removal from the new Regulations.
Main Reasons advanced.
- Prep/Emergency Seals are always getting damaged by mobile machinery travelling in and out of the panel. Prep seals lower the cross sectional area of the travel road and large machinery and loads cause frequent damage, which we then have to repair.
- Prep/Emergency Seals can always be quickly constructed. There is always lots of materials on hand to quickly build Emergency Seals.
If North Goonyella had of used Prep Seals in September 2018 in 9Nth would North Goonyella still be operating as a producing Mine to this day?
At Grosvenor would Prep Seals being installed have allowed the quick and effective sealing of LW104 in the month after the Methane Explosion?
Section 4.6 d) General Rules
d) ensure that before pillar or other block extraction in any district is commenced, preparations for the rapid erection of a seal in each entrance to that district have been completed. Such preparation shall consist of the installation and supply of all necessary materials so that seals that are, as near as practicable, air-tight may be erected in all such entrances within a period not exceeding three hours.
Recommendation out of the 1975 Kianga Inquiry.
report-on-an-accident-at-kianga-no-1-underground-mine-20th-september-1975
It was recommended by the inquiry that:-
(a) the knowledge of all member of the coal mining industry in Queensland be upgraded with regard to spontaneous combustion.
(b) changes be made in the Queensland Coal Mining Act to provide for:
additional protection against the propagation of coal dust explosions,
- monitoring or sampling of ventilation,
- preparatory seals and the recognition and delineation of responsibilities of persons with technical authority superior to a manager.
(c) additional analytical facilities to be provided for the industry.
Similar Recommendations came out of the 1072 Box Flat Inquiry but was not enacted.
6. VENTILATION
a) That provision be made for the rapid sealing of districts and mines.
EXTRACTS MRE’s 14th and 23rd January 2014 and withdrawal of Workers on the 3rd February 2014
140203 An event causing the withdrawal of a person from the mine or part of the mine states
At approximately 16:50 on 3/2/2014 analysis of a bag sample at 7North TG preparatory seal site taken from underground led to a Level 4 Tarp triggering the orderly withdrawal of persons from the mine. As part of the withdrawal of person from the mine the MG and TG preparatory seal sites were closed sealing the 7North Longwall panel.
As per the comments from the MRE’s of Albury on the 14 and of Dobson on the 23rd of January Preparatory Seals were in place even if the Tailgate was inaccessible due to >2,5% Methane General Body on the 23rd.
Prep seals are under construction in both MG and TG 7 Nth in the off chance that the situation develops into a serious heating event. (MRE 140114 Russell Albury)
An inspection of the area where the emergency seal was constructed in Longwall Tailgate 7 was not possible inbye of 1 c/t due to the presence of methane greater than 2.5% 5 metres inbye of the cut through (MRE 140123 Shaun Dobson)
