THE COLLIERY GUARDIAN

AND

JOURNAL OF THE COAL AND IRON TRADES.

Vol. CXII.	FRIDAY, DECEMBER 22, 1916.	No. 2921.

Goaf Packing at the Mohpani Mines.*

By F. L. G. SIMPSON.

Goaf packing is not practised in Indian mines, except
at two collieries, namely—at Mohpani, where it was
introduced by the writer in the year 1893; and at
Ballarpur,f where it was introduced by Mr. Davis in
the year 1913.

Up to that time, not only was packing generally
unknown in India, but longw’all working was also almost
entirely, if not quite, unknown; and the extraction of
pillars was confined to a few collieries where special
circumstances enabled them to be extracted without
recourse to packing.

The special circumstances which led to the introduc-
tion of packing at Mohpani were the thickness of the
seams, working under a large river, and liability to
underground fires. Similar circumstances have pre-
vailed at quite a number of Indian mines, where large
areas of coal were lost for want of packing.

The factors which prevented packing being generally
adopted were no doubt chiefly the expense, and the
absence of facilities for obtaining suitable material, and
for getting it into the mine and into the working places
without hindering the working of the colliery. In a
great many cases these factors are quite insurmountable,
but it is now generally recognised that enormous quan-
tities of coal have been lost, and enormous expenses
incurred for want of using packing.

mine,. The heating of the strata above this area led
some years afterwards to spontaneous combustion in the
No. 1 seam.

It will be evident from the foregoing remarks that there
was every inducement to adopt the packing system,
which was done on the following lines, obtaining a plen-
tiful supply of the required material from small hills and
rising ground close to the outcrop of the seams. The
system adopted was what is known as dry packing. •

The old field mines were worked by inclines, to the
dip, from the outcrops and shafts, one of which shafts
was about 1,200 ft. from the incline mouths, on the
opposite side of the river, and was 400 ft. deep. The
packing material was chiefly run in by the inclines in
trams, which were emptied by means of tipplers or
kick-ups into tips, from which the material was carried
away in baskets to the working places. These “ mutty
tips,” as they were called, were kept as near as possible
to the working places.

The trams, after being emptied of packing, passed on
to the landings or flats, which were also situated as near
as possible to the working places,'and were filled with
coal by the coal carriers. One set of carriers was
employed for the carrying and loading of the coal, and
a separate set of carriers for carrying and stowing the
packing into the workings. In some cases one carrier

walls, except a low foot wall, would be required behind
the face at all, except at special points, the natural
slope of the packing bringing it sufficiently close behind
the face to afford the necessary support to a fairly good
roof.

Timbering was done in the usual manner behind the
longwall faces, and as much timber as possible was
taken out before the packing was put in. Sufficient,
however, had always to be left in to enable the packing
to be thoroughly done, especially in all the stages but
the top one. This was most important, because if the
lower stages were not packed solid, the upper stages
were seriously affected by the coal settling down, and
by an uneven floor being left on the packing for the
upper Stages. These were factors that often made it
well worth while to leave most of the timber undrawn;
besides which the packing, when thus reinforced by
timber, had such a tremendous resistance to compres-
sion as practically to prevent any subsidence of the
surface.

Where the roof was good enough to allow the packing
to be kept far enough behind the face to give room for
several rows of timber, it was not difficult to get out a
good deal of the timber, and, at the same time, get the
packing (Solid, without affecting the upper stages, or the
safety of the packers; but where the roof was at all
tender, a good deal of timber had to be left in to prevent
falls or settlement, and to provide for the safety of the
packers.

The distance of the several stage faces behind each
other was determined by the nature of the roof, whether

Fig. 1.—Section of District Under River, showing Method of Packing.

The coal measures in the Mohpani district lie in
several separate areas, in two of which the seams have
so far been regularly worked, and which are known as
the old field and the new field areas. The old field was
the original area in which the coal was worked, and in
which packing was introduced.

The old field measures lie in a basin, which corre-
sponds very nearly with the shape of a large open space,
formed by the widening out of the Sita-rewa Valley,
and of a tributary valley, and a considerable portion of
the coal seams lie beneath the river bed, which here
forms a kind of bay or delta about half a square mile
in extent.

The coal seams dip south-eastwards under the river
from an outcrop across the river bed, and after running
some distance at an inclination of from 1 in 3 to 1 in 4,
they flatten out, and then rise up the opposite side of
a basin, and then, after running for some distance
further, more or less horizontal, they dip down again
under the newer measures.

The seams of coal in this area were :—No. 1 seam,
about 17 ft. thick (sandstones and shales about 60 ft.);
No. 2 seam, about 24 ft. thick (sandstones and shales
about 70ft.); and No. 3/4 seam, about 18ft. thick; a*nd
it will be evident that the extraction of such a thickness
of coal beneath a river without packing could hardly
fail to let in the water from the river, which, in full
flood, was some half a mile wide and 30 to 40 ft. deep.

A fairly large district had been worked by the author’s
predecessor in the No. 2 seam, beneath the river, on
the principle of non-extraction of the pillars, but leaving
them as small as was thought to be sufficient to support
the strata. This led to the crushing of the pillars and
the starting of spontaneous combustion, so that the
whole district had to be sealed off from the rest of the

* From Transactions of the Mining and Geological Insti-
tute of India.

f See Colliery Guardian, November 3, 1916, p. 856.

could carry both coal and mutty. The mutty carriers
filled their own baskets ait the mutty tip by means of
shovels and phaoras, or merely by hand, but there was
generally a man at each tip to help them to lift the
baskets on to their heads. There were sufficient pack-
wallers in the working places to build the necessary pack-
walls to keep the packing at the required distance from
the coal face, and there were sufficient men in the work-
ing places to throw the packing into such spaces as the
carriers could not throw it into direct from the baskets.

In certain cases the packing was not tipped into tips,
but was run closer to> the working places in the trams,
and filled direct from the trams into the baskets, either
by the tram being thrown on to its side, or on to its
end, or by the packing being simply lifted, basket by
basket, out of the tram. This made it easier for the
same carriers to carry both coal and packing, but was
considerably slower than the tip system.

The system of extracting the coal was by working
“ home,” the “ whole ” or first workings being driven
to the boundary of the district, and the pillars then
worked back or “ home ” by a system of modified long-
wall. The packing followed close behind continuously,
at such a distance from the longwall face as the nature
of the roof required. The seam was "worked back in a
number of stages, or parallel slices, according to its
thickness, one stage following behind the other at such
a distance as circumstances required. The bottom stage
was always the leading one, and the packing of that
stage formed the floor of the next stage, and so on. Of
course, the stages or slices were only really horizontal
when the seam was level, but when the seam was
inclined the stages were kept parallel to the inclination.

The packing material was worked from the quarry in
such proportions of walling stones and small stuff as to
suit the numbers of pack-walls required from time to
time, this depending on the nature of the roof. In
some cases pack-walls were required every 3 or 4 ft., in
others only every 6 or 8ft., whilst in others no pack-

in coal or stone, and by the distance of the pack-walls,
or the top edge of the packing behind the working faces.
The coal face in the upper stages had always to be kept
at such a distance behind the pack-wall, or the top edge
of the packing, in the lower stages, as to prevent any of
the stages being in any way affected.

Where the whole thickness of the seam has to be
worked, as in the No. 2 seam, which is all clean coal,
the several stages are in the successive slices of the
seam, but where there is a stone band or a part of the
seam not required to be worked, as in the case of the
Nos. 1 and 3/4 seams, the several stages are worked in
those portions of the seam which are being extracted,
and the intervening portion forms a floor or roof for the
other slices.

The drivings in the first or ” whole ” workings are
made in various parts of the seams as follow :—In No. 1
seam (of which the section is: Top seam, coal, 6ft.;
middle seam, splint coal, 5 ft.; bottom seam, coal, 6 ft.
—total, 17 ft.), the drivings are made in either the top
or bottom seam, or in both. In No. 2 seam (of which
the section is all clean coal, 24 ft.), the drivings are made
in either the top or bottom part of the seam, or in both.
In No. 3/4 seams (of which the section is : No. 3, top
seam, coal, 5 ft.; middle band, stone and coal, 5| ft.;
No. 4, bottom seam, coal, 7| ft.—total, 18 ft.), the
drivings are made in either the top or bottom seam, or
in both.

The drivings in the second workings (“ brokens ”
or “ pillar workings ” or “ longwall ”) are made in the
various stages in course of working, but the connecting
roads between the various stages are driven through the
intervening portions of the seam at such time and in
such manner as the circumstances of each case require.
In some parts of the old mines, the “ whole ” work-
ings were driven in the top part of the No. 2 seam, and
were gradually cut down to the bottom, so that the roads
were eventually 24 ft. high, but this was only rendered
possible by the fact that the coal was of such a nature