810

THE COLLIERY GUARDIAN.

April 16, 1915.

CURRENT SCIENCE

Fohr-Kleinschmidt Briquetting Process.

In carrying out this process, which is described by
T. Dach in Glilckauf, the pitch, in an unbroken condi-
tion, is heated by a steam coil, in a pan a, to about
100 degs. Cent., and run into the melting pan proper b,
in which it is heated to 130-170 degs. Cent, by direct fire
heat. It is next run into a small intermediate vessel c,
from which it is led to the steam-heated atomiser d,

operated by compressed air, and blowing a spray of
pitch into the mixing drum e, where the pitch solidifies
into a fine dust, resembling lampblack, whilst still
suspended in the air. The coal is delivered to the
mixer from the storage bunker f, by worm conveyors

AND TECHNOLOGY.

of briquettes, apart from the power required for the
drum and conveyors, again-t which latter must be
placed the saving of power for crushing and grinding
the pitch. The wages bill is about the same as for the
ordinary mixing process, two men being required, for
both. In any event, any increased cost of production
will be more than compensated by the saving in pitch.

the north the limits of the coal field are clearly defined,
following approximately the course of the River Stom-
as far as Chislet, where it extends over the Stour, and is

probably terminated here by a fault. On the west the
coal field is known to end eastwards of Brabourne, but
Prof. Dawkins finds no necessity to postulate here the
fault which Dr. Arber suggests. Dr. Arber makes the
long axis of the trough run north and south, while
Prof. Boyd Dawkins thinks this axis may possibly run
east and west, parallel to the axis of Artois, like the

Fig. 1.—Section through A-B (Fig. 2.).

R

I

I

'j

-J

Fig. 2.—Plan.







g and h, and an intermediate shute i. In the mixer it
comes in contact with the atomised pitch, with which it
is thoroughly mixed by the slow rotary movement of
the drum, assisted by the action of the baffle plates, and
the mixture moves gradually down the inclined drum to
the elevator pit k. The elevator I delivers the mixture
to the distributing worm m, which discharges it through
shutes n to the kneaders o above the presses. In the
kneaders it is further mixed, and is warmed by super-
heated steam, so that it reaches the presses p through
the distributing hoppers at a temperature of 55-80 degs.
Cent.

Other methods of preheating and melting the pitch
may be adopted, according to the character of the
material; or, as is the practice at the Engelsburg works,
liquid pitch from an adjacent tar distillery, may be used,
the liquid material being conveyed in tank cars q, and
discharged into a low-level tank r, to be forced thence
into the pan b by superheated steam. If the pitch can
be kept in a uniformly fluid condition, it can be run
into the atomiser through a tap, which enables the rate
of feed to be carefully controlled, thus giving a uniform
pitch content in the briquettes.

One of the chief advantages of this process is that it
dispenses with the inconvenient operations of crushing
and grinding the pitch, the dust from which, in the
ordinary course, is prejudicial to the health of the
workers; whilst the risk of damage to the mill, from
fragments of iron which may be present in the pitch, is
also obviated. Another advantage is that soft pitch can
be used, the binding properties of which are superior to
those of ordinary hard pitch; or tar may be substituted
for a portion of the hard pitch. The chief point of
superiority, however, lies in the possibility of obtaining
a thoroughly intimate and uniform incorporation of 4the
coal and atomised pitch. This results in a saving of the
binding medium in comparison with the ordinary
methods, in which more pitch than is really necessary
has to be employed in order to ensure proper agglomera-
tion of the mass throughout. This result is facilitated
by the extremely fine state of division of the pitch, in
which condition it has a greater binding power than
when merely ground, and therefore granular.

With regard to the actual consumption of pitch,
experiments, in which about 240 tons of briquettes were
produced, showed that 4'53 per cent, of mixed pitch
(3'53 per cent.) and tar (1 per cent.) was required. In a
second experiment, with 197 tons of briquettes, the
pitch consumption amounted to 3’99 per cent.; but in
this case a very soft pitch of special qualify was
employed. The average results of a number of smaller
Trials show that good briquettes can be obtained with as
little as 4’3 per cent, of pitch, as compared with about
5‘65 per cent, by the ordinary method of mixing, so that,
in practice, a saving of over 1 per cent, of pitch seems
feasible, which is equivalent to nearly 6d. per ton of
briquettes.

The system has not yet been tried with washed coal,
and its success under these conditions would appear to
depend on whether the necessary warming of the
washed coal to about 80 degs. Cent, does not prevent
the solidification of the sprayed pitch in the mixer, and
whether—in the event of the pitch remaining fluid—the
mixing will be as complete as in the case of cold,
unwashed coal. The cost of fuel or steam for working
the process is estimated not to exceed about f d. per ton

Sampling Coal for Analysis.

In Technical Paper 76, published by the United
States Bureau of Mines, Mr. A. C Fieldner calls
attention to methods of sampling coal for analysis when
the samples are taken in a mine or outcrop. The
sampling of coal deliveries has already been dealt with
in a previous report by Mr. G-. S. Pope. There is a
difference between taking'mine samples and sampling,
outcrops and prospecting holes. In the latter case the
sample is made to include all partings or binders less
than ^-in. thick, and all concretions or “ sulphur balls”
having a maximum diameter of less than 2 in., and a
thickness of less than J in. In collecting mine samples,
it is usual to crush the gross sample cut from the face.
This is quartered, after passing a ^in. screen, until a
3 lb. sample is obtained, but free impurities are crushed
to 4 in. diameter to secure a uniform distribution
during the process of quartering. The relation of mine
samples to commercial shipments is discussed. Thus,
coal shipped in open cars may gain or lose moisture
according to weather conditions. Calorific value also
alters, and it is difficult to assign any definite values for
the deterioration of coal while in transit, but d-viati< ns
of over 1 per cent, may occur. Methods of analysis are
given in detail, and it is pointed out that the figure for
volatile matter does not represent any definite compound
in the coal, but depends both upon temperature of
heating and also upon the rate of heating, factors which
are likely to vary considerably in different laboratories.
In the interpretation and accuracy of analytical results
the moisture figure is ambiguous because it does not
show the difference between extraneous and inherent
moisture. Similarly the ash may be due either to
inherent impurities or to the inclusions of portions
of roof or partings. The author then discusses Parr’s
“corrected ash” computation. Sulphur maybe present
both as pyrites and as sulphate. Pyritic sulphur is
objectionable, mainly because it tends to increase the
clinker formation in the furnace. The true significance
both of proximate and ultimate analysis is explained,
and finally a discussion of analytical results based upon
176 random analyses is given, as well as a description
of the United States system of classification and a
bibliography of publications on fuel technology.

The Kent Coalfields.

Prof. Boyd Dawkins has recently contributed to the
discussion on Dr. Newell Arber’s paper on the “ South-
Eastern Coalfield.” He considers that the classifica-
tion of strata by means of plants must always be
difficult, not only on account of the imperfect preservat i< n
of vegetable remains, but also because of the great
variation in the flora living in one region at one time.
He doubts whether our knowledge of the plant remains
of the coal measures is yet sufficiently complete to
enable these to form the basis of zonal classification.
He does not, therefore, accept Dr. Arber’s “ Transition
Series,” but prefers the older nomenclature of “ Pennant
Series” for the upper group. Prof. Boyd Dawkins
also calls attention to the peculiar coal-conglomerate
occurring beneath the upper group of coal seams in
Kent, pointing, in his opinion, to a distinct break in the
sequence of strata of the nature of a true unconformity.
Similar coal-conglomerates occur in South Wales below
the Pennant Series. With regard to the shape of the
Kent coal basin there is still much uncertainty. On

coal fields of South Wales, France and Belgium. He
thinks the most important contribution made by
Dr. Arber was the proof that the carboniferous lime-
stone underlies the coal measures throughout the greater
part of the field, and he agrees that correlation of the
sei ms is rendered difficult owing to their tendency to
split, causing surprising local increases in the number
and thickness of the seams. A diagram, given in the
Transactions of the Manchester Geological and Mining
Soci-ty, vol. xxxiv., Part IT., illustrates the main points
of difference in the views of Prof. Dawkins and Dr.
Arber with regard to the shap of the coal basin.

THE GERMAN AND AUSTRIAN COAL
AND IRON TRADES.

We give below further extracts from German
periodicals that have reached us, showing the course of
the coal and iron trades in Germany and Austria:—

German Foundrymen’s Association.

This association has issued a report, by Dr. Brandt,
on the negotiations between the iron foundries and the
combined foundries and ironworks with regard to the
assertions that the latter were price-cutters and com-
peted unduly within the sphere of operations of the
foundries proper, and also on the possibility of coming
to some general agreement on the question of price and
production. The discussion revealed that, in respect of
price cutting, there was fault on both sides. The
question of regulated output was shelved by the com-
bined works, but the author of the report advocates its
serious investigation, for mutual protection; and he
recommends the ordinary foundries to bring their plant
and methods more up to date, and to look carefully into
the matter of prime cost before offering fo undersell
competitors.

Increase of Cast Iron Prices.

The Eastern and Midland sections of the German
Foundrymen’s Association have decided to increase the
price of castings by 2 mk. per 100 kilos, from April 1.

The Iron Market in Rhenish Westphalia.

The rise in prices still continues, those for By-products
having followed the example of the Steel Union and
Pig Iron Syndicate, and in many cases the rates fixed
by the various conventions are being exceeded. Nearly
all the works are occupied to the full extent of their
capacity, which, however, on account of the scarcity of
labour, is only about two-thirds the normal. The
scarcity of many raw materials also has a restricting
influence on the output. The Siegerland ore mines
find it practically impossible to meet the demand, and
the same applies to the blast-furnace works The
extensive requirements of the army make it highly
desirable that the military authorities should allow as
many men as possible to remain at work. The ordinary
commercial demand is far below the war requirements,
and dealers for the most part hold stocks purchased at
former prices, so that they are able in some cases to
undersell the works.

Ore Market.—The Siegerland mines are producing
only about two-thirds their normal quantity, and cannot
satisfy the increased demand. Prices for running con-
tracts are still 12'80 mk. for raw ore and 19’60 mk. for