November 6, 1914.

THE COLLIERY GUARDIAN.

981

SOUTH AFRICAN MINING IN 1913.

EXCERPTS FROM THE OFFICIAL REPORT.

(Continued from page 921.J

Gob-Fires in Natal.

Reporting on the Natal Inspectorate, Mr. J. E.
Vaughan observes that the prevalence of gob-fires has
brought the question of mining the top seam, instead
of allowing it to fall into the goaf, into prominence.
This seam is not much inferior to the bottom seam at
many of the collieries, and it should certainly be mined,
as apart from the danger of leaving it in the goaf, it is
a valuable natural asset on which the Government ought
to receive something. Although the seam may not be
so profitable to work, as the bottom seam, it could be
worked at a profit in several cases, and would immensely
increase the lives of the collieries. In all new collieries
he thinks the Government should insist that all seams
should be worked when it is possible to mine safely, and
sell the coal from them at a profit. Some of the col-
lieries, notably the St. George’s, Durban Navigation,
Cambrian, Glencoe, and Hlobane, are extracting the top
seam, partially or‘totally; at the Cambrian the whole
mine is a top seam. It is probable that at other col-
lieries an attempt will be made to get some of the top
seam before drawing the pillars in the bottom, but a
large proportion of bottom seam pillars has been drawn,
and the top coal irretrievably lost.

Mr. Vaughan sees no reason to alter the opinion
expressed in his last year’s report that the amount of
good coal in Natal is limited. The amount of coal in
Natal is certainly enormous, but much of it is anthracite

tramming. Although the conditions had remained
apparently stationary for many months, the evidence of
actual fire appeared very suddenly in these sections.
The typical benzine smell, caused by distillation of the
coal, was pronounced, and was quickly followed by
carbon monoxide and smoke. The two fires in the
different sections occurred within an interval of about
a month, and although it was only necessary to build up
three or four entries in each section, the last entry in
each case was only built with great difficulty. The
third fire at this colliery was in reality a recrudescence
of one of those mentioned, and was caused by the col-
lapse of the stone between the two seams at once place,
thus allowing fresh air to gain access to the fire from the
bottom seam workings. Very great difficulty was
experienced in building the stopping necessary to isolate
the fire, on account of the great temperature and the
volumes of smoke and steam issuing from the place. The
work was ultimately accomplished by building up the
place first of all with sacks of dagga to keep back the
smoke and steam, after which it was possible to build
a substantial brick stopping on the outside. At the
Durban Navigation Colliery, on account of the system
of panelling which had been carried out since the com-
mencement of the mine, the occurrence was easily and
quickly dealt with by means of a few stoppings. The
gob-fire at the Natal Cambrian Colliery caused a good
deal of apprehension. It occurred in old workings, and

will probably appear, and an explosion of these gases dis-
tilled from the coal may result. It has been noticed that
where gob-fires have occurred in damp or wet sections in
the mines the development of the fire seems to have been
more rapid than in dry sections; possibly the action of
moisture on the iron pyrites in the coal may account for
this. In almost every case the smell of distillation has been
preceded by a greater or less interval in which blackdamp
was given off from the goaf. It seems that up to a certain
temperature in the goaf the coal absorbs oxygen from the
air, and beyond that temperature distillation occurs, the
products of which are then given off, and before they can
reach the goaf edge have to force out the blackdamp which
has accumulated in the goaf as the result of the oxidation
of the coal, which no doubt accounts for the appearance of
blackdamp before the benzine vapour. If the rise in. tem-
perature is slow, as it was at the Glencoe Colliery, the
benzine smell may be pronounced for months, and may have
no ill effects, when it tends to a feeling of false security, but
in time the temperature gradually rises until actual com-
bustion takes place, and carbon monoxide appears. Where
the spontaneous heating is rapid, the carbon monoxide may
appear almost at the same time as the benzine smell, but
whenever the benzine smell becomes apparent it may, I
think, be regarded as a certainty that a gob-fire is develop-
ing, and ^if steps have not been taken before to isolate the
district, such steps should then be taken without delay.”

At the end of the year the position as regards fires
was getting so serious that Mr. Steart instructed the
managers of the Durban Navigation Colliery, Cambrian
Colliery, Natal Navigation Colliery, Hatting Spruit
Colliery, St. George’s Colliery, and Glencoe Colliery, in
terms of section 13 (2) of the Act, as under :—

(1)	Before the extraction of pillars from a section is com-
menced, it must be converted into a panel by the erection of
substantial stoppings, so that should a fire occur it can be
at once sealed off.

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of poor quality, and could not be sold under present
conditions. A good many boreholes have been put
down during the year, and though good coal has been
proved in some areas, others in which it was thought
that good coal existed have been proved to be worthless,
the coal being burnt. Knowledge of the coalfields of
Natal and Zululand is not sufficient to warrant us in;
estimating the life of the fields with any degree of
accuracy; but from the known anthracite areas and the
geological features of the country, it is obvious that
much of the coal is burnt, and that by mining every
workable seam of marketable coal, an effort should be
made to save the resources of the country. It is folly
to throw away a good seam of coal, such as the top
seam in most cases, because the profit on it is not so
much as on the lower seam.

Some interesting remarks on gob-fires are contributed
by Mr. Steart, deputy-inspector of mines in Natal. He
states that during the past year seven new gob-fires
developed and were dealt with. At the Hatting Spruit
Colliery, two; at the Glencoe (Natal) Colliery, three; at
the Durban Navigation Colliery, one; and at the Natal
Cambrian Colliery, one. One life was lost as a result
of a fire at the Hatting Spruit Colliery. At the Glencoe
(Natal) Colliery preparations had been made in certain
sections of the mine for dealing with a possible out-
break of fire, as the inspectors of mines had considered
these sections very suspicious for some time past on
account of the rise in temperature (which at one point
reached 96 degs. Fahr.), also on account of the humidity
of the air at the goaf edge, and the omission of black-
damp at certain points. The sections had therefore
been isolated with stoppings, with the exception.of three
or four entries necessary for ventilation, haulage, and

although it did not require very many stoppings to
isolate it, yet the building of these was a difficult task.
The old workings had been wrecked by the explosion of
1908. The roof was everywhere fallen and shattered.
The work of cleaning away for foundations and stoppings
was very great, and in some cases the stoppings had to
be built over 20 ft. in height and width. Considerable
quantities of inflammable gas and carbon monoxide
were giving off from the old workings during the build-
ing of these stoppings. During exploration work in
connection with this fire, the manager, mine captain,
and Mr.. Steart were on one occasion badly affected by
carbon monoxide, whilst the small bird which they
carried in a cage to warn them of danger was appa-
rently unaffected. Although small birds are no doubt
useful in some instances as indicator's of the presence of
carbon monoxide, their experience on this occasion
showed that too much confidence should not be placed
in them. Mr. Steart adds :—

The development of the gob-fires in each ease during the
year seems to have followed much the same course as gob-
fires in previous years. In each case the cause has been
due to the spontaneous combustion of the ‘ top ’ seam which
has been left in the goaf, although in the case of the second
fire at the Hatting Spruit Colliery no pillars had been
extracted, but the * top ’ seam had fallen in old workings,
chiefly at bord ends, and spontaneous combustion had taken
place in the heaps of fallen coal. This colliery was one of
the few in Natal where firedamp had never been detected,
but during the building of the stoppings gas was observed
on several occasions. This gas was probably not firedamp
as generally understood, but coal gas distilled from the
heated ‘ top ’ seam coal. It was, of course, none the less
inflammable, and this circumstance shows that even in a
non-fiery colliery, should a gob-fire occur, inflamtnable gas

(2)	All entrances into a section which have to be kept
open for ventilation or tramming purposes must be provided
with doors so constructed that they are as nearly as possible
airtight when closed.

(3)	All old goaves as well as broken sections at present
working must be treated in the same way.

(4)	All stoppings built to enclose a section or fire must,
where possible, be inspected at least once a week, and the
results entered up in a book.

The work is now nearly completed, and in consequence
the pits are much safer than they were a few months
ago. Regulation 274 (15), as to the necessity of imme-
diately reporting an indication of a fire, is of assistance.
Before this regulation came into force there was at
some mines a tendency to say nothing of a fire till it
actually occurred, and, in consequence, when the
inspectors were informed of a fire, the position was
always serious. No doubt the managers were anxious
that inspectors should not know of an impending fire,
as they (the managers) were anxious to get as much
coal from the section as possible, and were afraid that
an inspector would order the removal of all persons from
the pit until the affected area was walled off. If prompt
means are taken to deal with a fire as soon as indications
of one are observed, it is usually a simple matter to
deal with, but where the heating up is allowed to
continue, and stoppings not erected till the benzine
smell and carbon monoxide are in evidence, the job is'
always one of danger and difficulty. At the majority
of pits development is now being laid off on the panel
system, and this will prove of great value in dealing with
fires of the future.

The Natal collieries remain as gassy as ever, and the
same stringent precautions to guard against explosions