1160

THE COLLIERY GUARDIAN.

December 15, 1916.

in three or four whole days. This was very convenient,
and it ought to mean that the ganister bricks could be
sold more cheaply than almost any other equally
expanded “Dinas” or “quartzite” silica brick.

It was not at all certain that there was any particular
virtue in the material itself, unless it were the circum-
stance that long practice had developed a real knowledge
of the best conditions for dealing with it. For instance,
sandstone from Parkgate rock could, the author had
found, be manufactured with no greater expenditure of
fuel than was required to make up the best Deepcar
ganister; and he believed that a time was coming when
silica bricks could be made out of whatever quartzite
came most cheaply to hand, by adding the as yet undis-
covered something which was present in the Deepcar
ganister. The ganister of the Halifax hard bed coal
varied in thickness from place to place—not merely
from mile to mile, but from yard to yard. It was a
most irregular bed of rock, and perhaps one of the
reasons why, in ganister mines, the roads did not go
straight was that the miners always wanted to take out
the ganister where it was thick, and to leave pillars to
support the roof where the ganister was thin.

Under-Clay of the Hard Bed Band.

The next bed would perhaps ultimately be of most
importance to the coal mining industry. At no great
distance above the Halifax hard bed or ganister coal,
there was another band of coal known as the Halifax
36-yd. band, or the Hard bed band coal. As a coal in
South Yorkshire, it was not of much account, but in
the northern part of the district, and in West York-
shire, it overlay a seat-earth of quite special chemical
characteristics. It was known that, by taking the pot
clay and grinding with it a quantity of unexpanded
ganister for making bricks, the composition could be so
arranged as to balance contraction of the pot clay against
expansion of the silica, and the resulting bricks would
keep their size, even though subjected to temperatures
round about 1,000 degs. Cent, for months and years.
The Germans and Belgians had the secret of that
scientific blending of materials. They took pure
quartzite, coarsely ground, and mixed it with clays, the
best of which they found it worth while to import from
this country, and from these mixtures they sent back
bricks, of which a goodly number of our by-product coke
ovens had been built. Now, the Halifax hard bed band
coal, in certain districts, had just that mixed composi-
tion at which contraction due to clay and expansion
due to silica were almost exactly balanced. Certain
coke oven walls built with bricks made in this country
had been found almost perfectly satisfactory, the bricks
not having changed their dimensions appreciably in
three years. In that coal field, at any rate, almost all
those walls had been made from clay mined from the
under-clay of the Halifax hard bed band in those parti-
cular districts where the contraction and the expansion
properties were suitably balanced. The author believed
that no very great reserves of the best qualities of
Hard bed band clay were at present available, but he
also believed that, by taking any good aluminous fire-
clay, and blending it with coarsely-crushed ganister or
other suitable quartzite material, they would eventu-
ally learn to make a very satisfactory material, which,
up to temperatures not exceeding 1,100degs. Cent.,
would keep to size and shape through many years of
continuous service. If there was one thing about that
coal field which required scientific research, it was this
question of balancing the expansion of silica against the
contraction of heated aluminous clays, and he thought
that, to the coal mining community, there was no tech-
nical question the solution of which more urgently
demanded attention.

Other Deposits.

In the South Yorkshire part of the coal field there was
no seam of refractory material above the Halifax hard
bed band which deserved an international reputation.
In the Huddersfield district, about Meltham, the work-
ing of refractory material associated with measures some
way down in the millstone grit was successfully in pro-
gress. In the. Bradford district, a very satisfactory bed
of clays underlay the Better bed coal and the Black bed
coals of Lowmoor, and for certain purposes both of these
had proved fairly satisfactory. In the seat-earth of the
Whinmoor coal, which was the next South Yorkshire
seam of coal, there was a refractory material in which
the siliceous part was a fair ganister, but which carried
small ironstone nodules which spoiled it, the clay admix-
ture being also too impure. The seat-earth of the Silk-
stone seam was also probably worthy of investigation,
but no information about it from the refractory point of
view was available. There were certain bands, serving
as holing dirt in the middle of the Parkgate seam, which
made good second-grade firebricks; there were also certain
fairly refractory bands associated with the Flockton
seam, and these ought to be investigated over a wider
area. There were also certain second-rate fireclays
associated with the Barnsley coal, which were useful
for furnace building in those parts of the construction
where the temperature was not allowed to exceed about
1,100 degs. Cent. But for high-class refractory
materials for iron and steel furnaces, the main supply
was certainly away down at the bottom of the lower coal
measures, and possibly also among the upper beds of the
millstone grit. In the search for improved refractory
materials, special effort should be directed to the detailed
study of the lowest members of the coal measures
succession, and to the investigation of materials which
look like fireclay or ganister, which were to hand among
the middle coal measures, rather than to a systematic
investigation of the middle coal measures from the
refractory supply point of view.

In Staffordshire and the Midland coal fields, there
was another zone of measures where the clays and some
of the sandstones made first-rate refractory materials,
namely, near the top. The Potteries probably owed
their location in part to the quality of the North Staf-

fordshire coals, but very largely to the character of the
Etruria marl, which division of the coal measures only
appeared in the Yorkshire coal field as a little patch
about Conisbro’, and thence south towards Maltby, and
perhaps for a little distance to the north of the River
Don, but was not a part of the Yorkshire series in which
there were any coals. Personal investigation of a cer-
tain number of fireclays which had been passed through
in the shafts of new pits east of Doncaster, indicated
that, something like 500 or 600 yds. above the Barnsley
bed, there was a zone of measures worthy of being
investigated as a source of supply of useful second-grade
firebricks. Probably at the outcrop these clays would be
in better condition than the materials traversed in the
shafts; those who controlled properties where the
Barnsley bed was from 500 to 700 yds. below the surface
and where the coal measures were not “ concealed,”
might come upon the outcrop of measures which
included refractory materials with very considerable
possibilities. That was something well worthy of
further investigation, but it was probably not much use
going further south than Maltby, or further north than
Shafton, to look for those upper seams of refractory
clays possessing the peculiar refractory properties of
the clays used for the making of saggars, and for sani-
tary and other big. ware in the Potteries district.

Basic Materials.

The only kind of basic refractory material yet dis-
covered in South Yorkshire was in the permian forma-
tion, where there occurred, towards the top of the lower
magnesian limestone, beds of a very pure dolomite
which had just that particular texture that enabled
them to be shrunk and made into “ basic ” or dolomite
bricks. Though unable to obtain specimens of dolomite
brick, the author exhibited some magnesian limestone
which had been shrunk with coke in a cupola at Steetly.
It consisted of the mixed oxides, almost an equi-
molecular mixture of oxides of calcium and magnesium,
was a very hard substance (able to scratch glass), and
had very special characteristics. The specimen shown
came from Steetley, and was manufactured from the
famous quarry so long worked for its first-rate building
stone. Only in the last decade had shrunk dolomite
come into prominence as a refractory material. For
that purpose the dolomite required to be fired at a tem-
perature which was high even compared with the
temperature required for the expanding of silica bricks;
a temperature at which lime began to volatilise, some-
where about 2,000degs. Cent., was frequently attained
in the cupola. Only vessels lined with shrunk dolomite
itself would stand the temperature, and the quantity of
fuel consumed in the manufacture was very consider-
able. Coke had generally been thought the material
most suitable for the fuel, but the Germans were very
successful in the application of surplus gas from coke
ovens to the same purpose, and probably collieries
having surplus gas, and being situated near the outcrop
of suitable beds of dolomite for making “ basic ” refrac-
tory materials, would, in time, apply that surplus gas
to the shrinking of this material. The bed of permian
limestone of the particular composition for the making
of “ basic ” extended over a strip of country ranging
north and south across South Yorkshire, and since,
when Sheffield changed its practice of steel making in
Siemens furnaces to melting and refining by means of
electric furnaces, there would be a great demand for that
material, some of those who had fuel not easy to dispose
of, might think about applying some of it to the manu-
facture of basic refractory materials.

The National Association of Colliery Managers and
Trades Unionism.—At a meeting of the council of this asso-
ciation, held in London on December 8, and attended by
representatives from every district in England, Scotland,
and Wales, the following resolution, proposed by Sir Francis
Brain (Bristol), and seconded by Mr. J. Gilchrist (Scotland),
was passed unanimously :—“ The attention of the council
of the National Association of Colliery Managers has been
drawn to an announcement in the public Press which states
that certain colliery managers in Scotland are proposing to
form a protective association on trades union principles.
This council, while not desiring to interfere with the indi-
vidual liberty of members, expresses the opinion that such
an association will be detrimental to the best interests of
colliery managers. It further wishes to again emphasise the
position this association has always taken up. This posi-
tion is embodied in the memorandum of association, which
states : ‘ Provided always that it shall not be lawful for the
association to impose on its members or to support with its
funds any regulation which, if an object of the association,
would make it a trade union.’ ’’

Record Prices for Coal in France. — According to the
Petit Parisien, there are 800 barges in French ports, con-
taining 300,000 tons of imported British coal, unable to
move for want of tugs. At the pit mouths of French collieries
500,000 tons lie waiting for transport, and a further 300,000
tons lie at various sea ports. Meanwhile, a number of
important munition factories are working short hours owing
to the lack of coal. The trouble arises in great part from
the military control of the railways, the military authorities
unnecessarily holding up large numbers of empty trucks for
several weeks at a time. In consequence of the transport
difficulties, the Coal Bureau, acting on instructions from
M. Sembat, Minister of Public Works, held a meeting of
representative manufacturers and importers. The decisions
arrived at were submitted to M. Sembat and M. Claveille,
Director-General of Transports, who ordered that they should
be immediately put into force. At every important port a
district coal bureau will be formed by the most experienced
importers, and, under the authority of the Government, will
exercise all the powers necessary to ensure regularity in
the importation of coal, and will adopt all measures to avoid
the holding up of coal in port, to make the best use of exist-
ing installations, and to ensure the equitable distribution of
imported coal for the needs of national defence. Recently,
a large coal dealer was able to exact the price of £9 Is. per
ton for an immediate supply of 250 tons of coal. This price
constitutes a record, even for France.

NEW WINDING PLANT AT
NEUMUHL COLLIERY, HAMBORN.

The rapid improvement made in the construction of
steam winding engines within the last few years has
enabled them to compete with greater success against
electric winding; and a novel system of mounting—or,
rather, a revival of the system introduced at the
Hannover Colliery about 30 years ago—has been adopted
in the new plant installed at the Neumuhl Colliery,
Hamborn, namely, the installation of the winding engine
in the top of the pithead tower, directly above the shaft.

The reason for the innovation—as described by Von
Hummel in a recent issue of Gliickauf—was the circum-
scribed space available at the pithead. The situation of
the shaft was determined by the necessities of the work-
ing conditions underground, and no room was available
for an engine house of the ordinary kind, unless at the
cost of other parts of the essential pithead plant. An
electric winder, mounted in the pithead tower, was con-
sidered, but discarded on account of the smallness of the
existing power station, and the expense of the requisite
extension, and a scheme for mounting a steam winder in
the tower (36 m. in height) was designed by the Gute-
hoffnungshutte, Oberhausen.

Fig. 1.—Elevation of PitheadjTower.

The installation was designed to raise 134 tons of coal
per hour, from a depth of 600 m., by an average of 32
winds, in triple-deck cages, with two tubs—in single file
—to each deck. The net load was 4,200 kilogs., and the
maximum winding speed 16 m. per second. The pre-
scribed rope dimensions were : Diameter, 60 mm.;
weight, 12*7 kilogs. per running metre. The maximum
output of the engine was calculated at about 2,500 indi-
cated horse-power. Special points for consideration in
the construction of the tower and the engine were that
the considerable forces developed by the reciprocation
of the engine parts in the top of the tower would set
up swaying movements in the structure, and that pro-
vision would have to be made for their absorption.
Since considerations of space and w’eight prevented the
use of a direct-coupled horizontal engine, the adoption
of the vertical type was projected; but this idea was
finally abandoned in favour of an ordinary double-
cylinder horizontal engine, with helical reducing gear.

The Tower.

The pithead tower (fig. 1) is constructed of iron
throughout, and square in plan, each side being 12 m.
long. The four strong corner posts transmit all the
vertical loads—and, by the aid of diagonal bracings, all
the horizontal forces as well—to the masonry founda-
tion. The feet of the posts are'arranged so as to enable