1. Although the hazard involved in the use and
handling of explosives, expressed as persons
killed or injured per million shots fired, is
not high, the large number of shots fired
annually results in a comparatively large number
2. Shotfiring accidents may be divided into
two main categories - those due to some failure
of the explosive or ancillary equipment to
attain perfection and those due to failure of the
human element. Continued research and develop - :ment in explosives technology have resulted in
a reduction in the former class but the latter
type forms a large and increasing percentage
of the annual total of accidents.
3. The statistical techniques developed by
Wynn and used in this work provide a valuable
means of representing graphically the significance
of any differences existing between calculated
1 expectations and observed numbers of accidents.
4. Only two National Coal Board Divisions
showed significant differences in accident rates
from the rest of the country over the period for
which figures were available. The Scottish
Division was very much worse, and the North
Eastern Division very much better than the average
for the rest of the country.
On the limited amount of information
available, it appears that shots in locations other than coal seams or stone mines present a
hazard greater than would be expected from the
relative numbers fired in these situations.
5. Over half the annual total of shots fired
in National Coal Board collieries are in coal,
initiated by electric detonators and fired
singly, and this class is still by far the most
important in British coal mining practice.
Simultaneous and delay firing offer potential
safety as well as operational advantages, but no
measure of these can be obtained with the
limited information at present available.
6. Alternatives to explosives offer safety
advantages over conventional explosives and
should give corresponding benefits in a
reduction in accidents.
7. Pulsed infusion shotfiring, in the
comparatively limited circumstances in which it
may be usefully employed, yields safety,
operational and economic advantages over
8. Limited evidence suggests that the use of
water ampoules in conjunction with conventional
explosives gives consistent reductions in the
dust produced by shotfiring in rippings but
widely variable figures have been recorded in
the dust counts before and after the introduction
of these devices in coal blasting operations.
9. Off -shift firing offers great potential
advantages in comparison with conventional
practice, and these are confirmed by the low
accident rate in the North Eastern Division and
the Central East Area of the Scottish Division.
10. The general standard of practice achieved
in shotfiring is very much below the minimum
required by law and demonstrated to the shotfirer
in the training period. This is due to a
combination of lack of effective supervision
and the needs of production clashing with safety
11. In orthodox hand- filled longwall working
when the coal preparation shots are fired on the
production shift, the nature of the shotfirers
work, with periods of great activity alternating
with periods of comparative idleness, leads to
carelessness and skimped precautions.
12. In orthodox longwall working, very limited
shelter is available on the coal face, and it is
frequently necessary to rely on cover which
cannot possibly be considered satisfactory.
13. It is seen from the accident positions of
the North Eastern, North Western and East Midlands
Divisions that the provision of portable shelters
in gate roads effects no sensible reduction in
14. Although no satisfactory concrete explanati
for the high shotfiring accident rate in the
Scottish Division could be found, it is
suggested that a combination of difficult
natural conditions, making men more reluctant to
retreat a sufficient distance from the shots
and a national temperament not amenable to
discipline might explain the difference between
Scotland and the rest of the country.