December 22, 1916.

THE COLLIERY GUARDIAN.

1219

fusible ash—and also gave the necessary temperature
at the zone of combustion to ensure the minimum
amount of carbon dioxide in the gas. The blast
pressure, eight-tenths to nine-tenths, gave an indication
of the height of fuel and ash in the producer, and caused
a minimum of trouble to the attendants. In general,
high gauge pressure corresponded with high carbon
dioxide and high blast temperature.

Graphite as a Cylinder Lubricant

In a paper recently read before the Birmingham
Association of Mechanical Engineers, Mr. W. E.
Johnston stated that “Aquadag” (a colloidal solution
of graphite in water) had been used for over four years as
the sole cylinder lubricant for a plant consisting of three
50 kw. high-speed steam dynamos, two deep borehole
pumping engines, and various auxiliaries, working with
steam at 120 lb. gauge pressure from three Lancashire
boilers, unprovided with a superheater. No trouble was
experienced either from clogging of passages, the
presence of graphite in the boilers, or from inefficient
lubrication. All the rubbing surfaces have remained in
excellent condition, and the slide valves especially show
no traces of scoring. The boiler surfaces are clean
down to the metal and entirely free from any suspicion
of pitting . The particles of graphite are so minute that
they remain in a permanent state of suspension. The
electric charge in the constituent particles of the
colloidal solution prevents their coagulation ; but if the
charge is distroyed by the addition of a little acid or
other suitable electrolyte, the particles coagulate and
deposit, and can then be readily filtered out. To ensure
an even supply of the lubricant- to the engines, the
author has devised a simple form of sight-feed
lubricator in which the “Aquadag” ascends in drops
through a column of paraffin oil.

MANCHESTER GEOLOGICAL AND
MINING SOCIETY.

A meeting of the Manchester Geological and Mining
Society was held on Tuesday last at the rooms of the
society, Manchester, Mr. William Pickup, the presi-
dent, being in the chair.

The President remarked that Mr. Lantsberry, the
joint author, with Mr. Drummond Paton, of the paper
to be discussed that afternoon, was unable to be present
owing .to indisposition. Mr.. Paton desired it to be
understood that the paper was mainly Mr. Lantsberry’s,
though he had given him substantial assistance in the
preparation of it.

Mr. Paton said that Mr. Lantsberry wished to accen-
tuate the fact that the paper was not intended to cover
the present British conditions, but W’as really a demon-
stration of what had been done on the Continent. The
original designs were made by British engineers, but the
trade was allowed to pass into Continental hands. They
were indebted to such men as Yeadon,' Sutcliffe, and
Middleton for the initial ideas, and to Continental users
for the developments which had since taken place, of
which the paper was a resume. It was also intended
to emphasise the importance of the utilisation of
apparently useless fuels.

Mr. Drummond Paton read the paper on “Fuel
Economy, with Special Reference to Briquetting.”
(See page 1228.)

Discussion.

The President moved a vote of thanks to the
authors for their valuable paper. The subject of
briquetting, he said, was coming more and more to the
front, and the utilisation of small and inferior coal was
a matter which the Institution of Mining Engineers
regarded as ripe for research work.

Mr. Harrison seconded, and the resolution was
carried.

Mr. Lomax (Bolton) said there were several points
he would like to lay before the members in connection
with the utilisation of waste coals. He had spent con-
siderable time in the microscopical and chemical exami-
nation of coals of various kinds, chiefly with a view to
avoiding much of the waste which existed at the present-
time. Lately, he had been experimenting with coal
dust, mixed with a certain amount of stone dust, which
had been collected in the roads of collieries in the
Lancashire district, and other refuse matter generally
found in haulage ways. His object was to ascertain
how much of the waste materials could be put to some
use in connection with the important question of fuel
consumption. He had that morning made three
briquettes from three different dusts, and he produced
them for examination by the members. They would
find that they were quite solid although no admixture
of any secondary matter had been’used. The briquettes
were simply composed of coal taken from three seams
and heated, under pressure, to 350degs. Fahr. He
discovered that from two coals he produced, one fat and
one lean, it was impossible to make briquettes, but if
the two were ground up and mixed, fairly good results
could be obtained. ‘If a machine could be invented
enabling the coal to be heated, and then ground up as
fine as possible, good briquettes could be made without
any secondary or binding substance. Of the dust he
had been dealing with, 90 per cent.,would pass through
a 400-mesh. In reply to a question, he pointed out
that the pressure applied to the briquettes was obtained
by an ordinary screw key, five turns of which produced
all the pressure that was necessary, after filling the
mould tightly by hand. The swelling of the bitu-
minous or resinous matter in the coals caused by the
heating acted as the coagulating medium, and an exami-
nation of the briquettes under the microscope showed
practically no division between the particles of dust.
The length of time necessary for heating purposes was
four or five minutes. In one of the briquettes there

was 8 or 9 per cent, of ash, and in another 2| to 3 per
cent. He was convinced that the difficulty experienced
in making satisfactory briquettes at present could be
overcome if coal itself was used for the purpose without
the admixture of such refuse as the authors of the paper
had referred to. The presence of pyrites, however,
either in strings or concretionary form, was undesirable,
because his investigations tended to show that as soon as
the briquette, after the pressure was taken off, came in
contact with air, some action was set up in the pyritic
matter, which caused it to fall. Seams which contained
a large amount of pyrites, therefore, would be useless
for briquetting purposes.—In reply to tfie President,
Mr. Lomax said that he believed the briquettes would
stand rough handling and weather conditions without
binding materials. He had some which had stood the
weather for quite a long period.

Future of Briquetting.

Mr. Noah T. Williams (hon. secretary) said the
paper contained a great deal of information, and as it
was the first the society had had dealing with the sub-
ject of briquetting, the members were very much
indebted to the authors for the care they had taken in
its preparation. The most important lesson it taught
was that in this country we were far from making the
best use of coal and its by-products. That fact had been
brought home to us very strongly by the war, 'and it was
only necessary to mention two things that we had felt
the want of to a large degree—aniline dyes and toluol—
both of which could be obtained from coal. It had
been pointed out by the authors that the output of
briquettes from Germany was one-half of the world’s
total production, which was probably accounted for by
the fact that most of the coal found in Germany was
very soft. He took it that the figure quoted in the
paper included the brown coal briquettes. We, in this
country, were arriving at a time when the thick and
best seams of coal were being worked out, and it would
undoubtedly be necessary to introduce briquetting on a
much more extensive scale than had been done in the
past. The present output was something like million
tons, and the industry was practically confined to South
Wales, very little being done elsewhere. It was pointed
out in the paper that very hard coals were most diffi-
cult to briquette alone, unless so much binding material
was added as to make the process unprofitable, and in
that connection he might mention that in South Wales
experiments had been carried on with a view to making
briquettes out of anthracite. It was true that they
could be made, but they were not a success, because, as
soon as they were put on the fire, they fell to pieces on
account of the pitch melting before the coal took fire.
It was absolutely essential in that instance to put in a
proper amount of bituminous coal along with the pitch,
so as to have the binding and coking effect. The
authors expressed the opinion that the ash contents
should not exceed 12 per cent., and that there was no
difficulty in securing that figure with the modern wash-
ing plant. Earlier in the paper it was -stated that, in
screening and washing operations, large quantities of
small coal and sludge were produced, but he did not
follow whether it was intended to suggest- that that
could be used for briquette making or not. At any rate,
he would venture the opinion that the sludge and waste
coal could be more profitably used as dust for firing
under boilers. The percentage of pitch necessary to
effect a proper adhesion of the particles of coal in the
finished article was given as between 7 and 10 per cent.,
but in South Wales he understood much more pitch was
used than on the Continent. The figure for South
Wales, he believed, was something like 12 per cent.,
and .he should like to ask if the authors could give any
information as to why so much was used. It was
unquestionably a very important item in the cost of
production, and if its use could be eliminated altogether,
it would be of great service to the industry. As Mr.
Lantsberry observed, there was ample scope for research
in that direction. It might be interesting to mention
that a press was brought out some years ago, known as
the Ronay press, which was invented by an Austrian
engineer, the object of which was to do away with bind-
ing materials, such as pitch and lime, or any other
coagulants used in connection with the making of
briquettes. The pressure, he believed, was something
like 10 tons, much higher than was employed in the
ordinary process, but it was essential to have a coal
which contained a minimum of 20 per cent, of volatile
matter. The coal, of course, was heated before it was
introduced into the press. He would like to know
whether that particular press had passed the experi-
mental stage and come into general use, because it
would solve one of the most difficult problems connected
with the briquetting industry. With the adoption of
pitch, they had by no means reached the final stage of
binding materials, and if these could be done away with
altogether, a great step forward would have been accom-
plished. As Mr. Lomax had shown, it was possible to
manufacture by pressure alone, but the question to be
considered was whether the commodity produced would
stand heat and weather conditions satisfactorily.
Another test was whether it would fall to pieces before
it had burnt properly.

Mr. Lomax suggested that one of the briquettes should
be placed on the fire. This was done, and Mr. Stanley
Atherton pointed out that it took 4J minutes to flame,
and started to burn in 5| minutes, and some time after
it had not shown any signs of falling to pieces. On the
question of pressure applied by Mr. Lomax, it was
explained that the cubic contents were actually reduced
by about one-seventh.

Cost of Making Briquettes.

Mr. Williams went on to say that the cost of pro-
duction appeared to hamper the progress of the Ronay
press, which had to be made extremely strong. He
regretted the authors had not given them more informa-

tion in regard to the cost of the installation, and the
value of the paper would be greatly enhanced if the
outlay necessary for a plant producing 50 or 100 tons a
day had been quoted. Mr. J. S. S. Brame, in his book
on “ Solid Fuel and Liquid Fuel,” put the cost of an
experimental plant for producing briquettes in the
United States at something like 4s. 2d. per ton added
on to the cost of the fuel itself. If that aspect of the
problem was dealt with by Mr. Lantsberry and Mr.
Paton, the paper would be a valuable one for future
reference.

A Member, dealing with the question of waste in
mines, observed that in Lancashire the amount left in
mines unworked was very very small.

Mr. Stanley Atherton remarked that heating up to
350degs., and then reducing the cubical contents by
one-seventh by pressure, would practically change the
spores in the coal to such an extent as to produce an
artificial cannel.

Mr. Lomax said that after being pressed it was impos-
sible to distinguish any spores at all; it was one con-
glomerate mass. He also exhibited a number of distil-
late obtained from coal dust.

Mr. Drummond Paton, replying to the discussion,
remarked that he was delighted to find that Mr.' Lomax
was combining his geological investigations with a
practical application of the results which -were likely to
bear out the contention that coal dust was a paying
commodity. Exception had been taken to a figure of
15 per cent, which he had given as the amount of coal
left ungotten in collieries. It was not his desire to
look for a point of dispute between colliery engineers
and the outside industrial world, but rather to show that
material was wasted in big quantities, out of which a
good commercial commodity could be obtained. He was
probably an extremist, but on occasions he had had his
figures challenged, and, on making an examination, he
had found not 15 per cent., but as much as 60 per cent,
was left in. He had, on the other hand, seen many
mines in the Lancashire territory where there was cer-
tainly not 15 percent, left in, and he would describe that
as good mining. What he particularly wanted to do
was to plead for the utilisation, to the utmost limits, of
the coal lying in mines and actually brought to the sur-
face. Every ounce of coal on which labour had been
expended should be utilised to its fullest capacity, and
he was convinced that, by distillation, another section
of utilisation could be provided which had not up to the
present time been exploited. He hoped colliery people
would realise to what extent the value of the output of
the mines could be increased by adopting a process of
briquetting. Mr. Lomax mentioned that he had pro-
duced his briquettes without any adhesive mixture, but
if an excessive heat was applied in the process, some
of the volatile oils must be lost, and that point had
perhaps been lost sight of. With regard to cost, 2s.
per ton was practically a universal figure throughout
the world for the grinding of coal to a very fine state.
As to the effect of the presence of pyrites, he was pre-
pared to admit that there might be some special action
which produced a bursting condition at critical temper-
atures. He had seen a briquette which was practically
made on the basis of the Ronay press, and he under-
stood a German firm had got the actual process. No
gum was used in the manufacture, and there was no
disputing the fact that a briquette could be manufac-
tured by terrific pressure, but it was a question of which
was the simpler way, the application of pressure or the
use of a plastic medium.

A New Miner’s Lamp.

Mr. Gerrard exhibited a miner’s lamp made by
Turquand and Kew,* of London, which, he said, had
passed the Government tests, and been approved. It
was claimed by the patentees that it would reduce first
cost as near as possible to that of an oil lamp, and by
their system of maintenance the lamp could be
re-charged, cleaned, etc., at a minimum expenditure of
money, time, and labour. The cost of renewals had
been kept to the lowest possible limits, and the arrange-
ment of the working parts was such that each part
could be replaced quite easily by fairly unskilled labour.
An interesting feature was that either acid or alkaline
accumulators could be used without alteration to the
case, so that a colliery buying acid type batteries could
make trials with alkaline batteries without disturbing
their installation. Another important factor, in his
opinion, was that the lamp could be sealed hermetically,
having a gastight joint which prevented the entry of
gas, and also allowed the lamp to burn satisfactorily
when immersed in liquid. A concentric bulb holder,
reflector, and switch combined was so arranged that the
bulb could be renewed in a few seconds without taking
the lamp to pieces. A luminous white reflector made
the lamp visible in the dark after the light had been
extinguished, and a patent switch fixed in a gastight
chamber operated automatically by breaking the circuit
if the glass or lamp top was disturbed or smashed. No
celluloid was used in the manufacture of the lamp.—In
reply to questions, Mr. Gerrard stated that the candle-
power was 1| to 2, and the weight 4| lb. The pre-war
cost was about 12s. fid. to 14s., but under present con-
ditions it would, of course, be somwhat higher.

Mr. Gerrard was thanked for his demonstration.

* See Colliery Guardian, November 17, 1916, p. 957.

At Whitehaven tribunal on Thursday of last week, appli-
cation was made for the exemption of a mining engineer,
37, married. in the employ of Lord Leeonfield, on the ground
that he was carrying out work of national importance. He
was rejected at Carlisle in March, and an re-examination last
Wednesday was only passed for class C2. Exemption was
granted.