436 THE COLLIERY GUARDIAN...

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March 2, 1917.

CURRENT SCIENCE

Benzol Recovery from Coal Gas.

In a paper before the Midland Junior Gas Association ?
Mr. T. F. E. Rhead discussed from the physico-chemical
standpoint the problem of the extraction of crude
benzol from coal gas, using creosote oil as a washing
medium, and formulated the following practical conclu-
sions :—The efficiency of washing is greatly improved by
using a cold oil—say, 15 degs. C.—providing the creosote
keeps sufficiently fluid. The lighter oils in creosote—
180 degs. to 220 degs.—help the washing process by
lessening the viscosity of the creosote, but are objection-
able in that they are readily distilled out by steam and
contaminate the crude benzol. Naphthalene helps to
lessen the viscosity, and thereby helps the washing; but
it is very objectionable in that it prevents good
extraction of naphthalene from the gas, and may even
add some to the gas under certain con litions of quantity
and temperature. Creosote fractions boiling above
300 degs. greatly increase the viscosity, and are very
objectionable if present to any extent. A good creosote
should remain as fluid as possible at 10 degs. to 15 degs.,
give little oil distillate when steam distilled, and have
as low naphthalene content as possible. Greatly
improved cooling of debenzolised oil from the crude
still is obtained by using a creosote of which the
viscosity rises very little when cooled to 10 degs. to
15 degs., and better temperatures are obtained for
benzolised oil entering the crude still. The efficiency of
washing is greatly improved by increasing the intimacy
of contact between the oil and gas. Washers on the
spraying or atomising principle appear to offer the best
field for development in this direction—namely, an
increase of surface per volume of washer and minimum
back pressure. When using mixtures of blastfurnace
and coal tar creosotes specific gravity is no criterion as
to whether a creosote is “ spent ” or not, and its
magnitude. Viscosity is the best test, and should be
between 8 to 9, with a maximum of 10 (rape oil = 100).
A sufficient quantity of creosote should be in circulation
to prevent the light oils taken out and contained in the
crude benzol in stock leaving a creosote of high viscosity.
If light oils are sold with crude benzol, then either the
creosote must be changed more frequently or the
equivalent quantity of similar light oils added to take
the place of those in the crude benzol.

Gas and Potash from Cement Kilns.

At the Hagerstown works of the Security Cement and
Lime Company a Cottrell plant was installed last year
for the recovery of potash from the kiln gases by the
aid of high-tension current at 70,000 volts. The power
supply (Engineering News) is three-phase current at
440 volts and 60 cycles, and the electrical equipment
consists of four I5-borse power, 10 k.v.a., 220 volt single
phase 60-cycle 1,800 revolutions per minute motor
generator sets, each directly connected to the shaft of
a rotary rectifier, and four 220 to 70,000 volt 60-cycle
10 k.v.a. transformers of special construction. The
volume* of gas handled is approximately 180,000 cu. ft.
a minute at a temperature of 900 degs. Fahr., and with
two kilns 7 ft. by 100 ft. and three 8 ft. by 125 ft. the
production of potash dust averages from 20 to 25 tons a
day of 24 hours. The dust contains from 5 to 10 per
cent, of potash in the form of potassium sulphate, and
being in a very finely divided state, is highly suitable for
fertilising purposes.

It is noteworthy that the potash plant has been the
means indirectly of increasing the production of cement
clinker and also the fuel economy. It has brought
about more continuous operation of the kilns, because
it has required better attention on the part of the kiln
operators, and this automatically makes the clinker of
more constant quality. It is found also that the best
recovery of potash is coincident with the best burned
clinker.

Oil Washing for Benzene and Toluene.

Mr. W. G. Adam (Gas World) reports the result of
experiments undertaken to ascertain the effect of oil
washing on the illuminating power and calorific value,
in addition to the sulphur and naphthalene content of
the gas. The work was commenced with a rotary
scrubber dealing with about 30 cu. ft. of gas per hour,
in which was determined the relative efficiencies of
various wash oils. The results obtained were confirmed
on a plant dealing with 100,000 cu. ft. daily, in which a
number of washing, fluids were used and the effects on
the gas recorded.

W ith regard to the effect of oil washing on quality of
gas, the author states that while the removal of benzol
from the gas effects a reduction of about 50 per cent,
in the illuminating power, the calorific value is only
affected to about 5 per cent. The sulphur content of
clean gas consists of thiophene, carbon bisulphide,
carbon oxy sulphide and mercaptans, and it is possible
to remove all these except the carbon oxysulphide by
means of oil washing, and the gas would then test
about 10 grains of ■ sulphur per 100 cu. ft. Thorough
washing of the gas with oil will remove all but the last
one or two grains of naphthalene, and the vaporising
(not spraying) of paraffin into the gas in sufficient
quantity is an efficient preventive of the deposition of
naphthalene from oil-washed gas.

The best wash oil is one which is of the maximum
boiling point, consistent with sufficient fluidity at
ordinary temperatures, treating 100,000 cu. ft. of gas
per day, in which the following materials were used as
the washing medium: Fluid creosote (containing 8 to
25 per cent, tar acids), cresylic acid and heavy pyridine

AND TECHNOLOGY.

bases. All gave very similar results both as to quantity
of benzol, etc., absorbed and the quality of crude spirit
obtained. Various tars were experimented with, but
were all found to give low absorption of benzol, etc.,
and it was determined that to secure efficient extraction
a very much larger quantity of tar bad to be used than
was produced per ton of coal. A consideration of the
conditions prevailing on coke ovens predetermined this
point. Coke oven gas frequently contains tar fog. and
this is completely absorbed by the oil in the scrubber.
The repeated steam distillation of the oil gradually
carries away the creosote, leaving behind the tar. The
result is that after a time the oil becomes tar, is said to
be “ fatigued,” and has to be renewed.

A green oil was found to give absorption up t_> 6 and
7 per cent., a crude spirit containing frequently as low
as 5 per cent, of heavy oil and a low naphthalene
content of the gas. It, was thus found possible to
obtain high efficiency in the absorption, less oil having
to be circulated. This resulted in an increased capacity
of the scrubber, heating, cooling and distilling plant,
and economies in both steam and cooling water. The
crude spirit contained no tar acids, and thus required
no soda wash prior to rectification. A low heavy oil
content of the spirit gave economy of acid in the C.O.V.
wash, amounting usually to a.50 per cent, saving. With
the use of green oil and complete stripping of the gas
it was found possible to keep the naphthalene at 4 grains
per 100 cu. ft, and interesting results in the distribu-
tion of the gas were obtained. It was found that after
the old deposits of naphthalene in the mains were
removed no stoppages, even in the smallest services,
were experienced.

The oil washing of coke oven gas is usually carried
out in the presence of ammonia, sulphuretted hydrogen
and other impurities. In this condition the gas and the
wash oil have an energetic action on steel and wrought
iron. For this reason the plant has to be made almost
entirely of cast iron. This action is possibly influenced
by the presence of cyanogen. No corrosion of wrought
iron or steel is experienced when clean gas only is
scrubbed.

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THE CONTROL OF MINES.

The executive of the Miners’ Federation held a
meeting, on Tuesday, in London to consider the position
of the workmen under the Control Order. It was
agreed that in existing conditions the present wages
must be continued, that further rises in the cost of
living must be followed by corresponding increases in
the wage rate, and that the present standard of living
of those employed in the coal mining industry must be
maintained. After the meeting, one of the men’s
leaders stated that the Government, by taking control
of the industry, destroyed the economic basis by which
wages are fixed. The present wage must be maintained
intact, and further rises in the cost of living must be
followed by further rises in wages. With high prices,
the present wages are only an existence for the
workmen.

The executive of the Miners’ Federation of Great
Britain had an interview on Tuesday with the President
of the Board of Trade with a view to .ascertaining tLe
position of miners under the Government scheme of
control, both as regards their working conditions as
trade unionists and on the question of wages. The
council also desired to make clear the attitude of the
workmen on the question of wages, rise in food prices,
and the standard of living.

The interview with Sir Albert Stanley, who was
accompanied by Mr. Guy Calthrop and Sir Richard
Redmayne, lasted about an hour and a-half. The
position was discussed by the men’s representatives
with complete freedom. Sir Albert Stanley’s reply was
sympathetic. It was stated that an Advisory Com-
mittee of 10 representatives—five coal owners and five
workmen—would be appointed to act with the Coal
Controller. The workmen’s representatives have already
been chosen—Messrs. Robert Smillie (Scotland), Vernon
Hartshorn (South Wales), W. Straker (Northumber-
land), H. Smith (Yorkshire) and Stephen Walsh, M.P.

Following the interview at the Board of Trade the
miners’ executive met at the Imperial Hotel, under the,
presidency of Mr. R. , Smillie, and approved of the
appointment of the workmen’s representatives.

At a meeting of the Coal Conciliation Board on
Wednesday the following resolution was adopted :—

The owners have considered the application made by
the workmen's representatives at a meeting held on the
31st of January, viz. .- — That having regard to the
increased cost of living, the existing war bonus be
increased from 13'8 to 18’8 per cent., and are willing on
this ground, and this ground only, to agree to increase
the existing war bonus from 13’8 to 18 per cent., subject
to clause 3 of the conditions agreed to on the 24th of
May, 1915, and to the further condition that no general
application for any further increase, either as bonus or
otherwise, be made by the workmen’s representatives
throughout the area within the period ending August 31,
1917, and which is accepted by the workmen's repre-
sentatives. The increase to accrue from Monday the
19th inst. at those collieries where that is the first
working day in the pay week, and where the first
working day in the pay week is after the 19th, then the
increase to accrue from such day. Whatever arrears are
due are to be paid with the week’s pay at the pay date of
the week ending 10th March.

The increase of 4’2 per cent, means an addition
varying from 3d. per day to boys to 6d. per day to coal
hewers and higher paid grades of workmen. As the
number of workmen employed at the pits of the
Federated area is 350,000, this is approximately an
increase of £40,000 in the weekly wages bill.

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COAL TRAFFIC ON RAILWAYS AkD

CANALS IN 1915*

The following table shows the coal and coke carried
by the various systems of railway, canal, and other
inland navigation companies from colliery districts in
the United Kingdom in 1915 and 1914

1914.

Railways, England ai d Wales Tons.

Furness (coal) ............ ............... 153,265

Great Cent'al (coal and coke) ... 13,583,303
Great Northern (coal) ........ ... 7,947,661
Great Western (coal and coke)... 20,521,077
Hull and Barnsley (coal and coke) 2,110,7531

Lancashire and Yorkshire (coal

and coke) ................... 8,526,551

London and North-Western (coal) 21,351,2 '4
Maryport and Carlisle (coal and

coke) .......................	330,611

Midland (coal and coke, excepting

gas coke) ................... 26,593,971
North-Eastern (coal and coke)... 37,435,639
North Staffordshire (coal and

coke) ....................... 3,596,447

South Yorkshire Joint Line

Committee (coal and coke)...	831,181

Taff Vale (coal and coke)....... 14,872,879

Railways, Scotland: —

Caledonian (coal and coke) ..... 11,989,693
Glasgow and South - Western

(coal) ....................... 3,465,686

North British (coal and coke) ... 17,540,201J

1915.
Tons.
138,053
... 13 913,038
... 8,524,741
... 21,346,650
... 1,812,781f

... 8,811,114
... 20,812,417

339,032

... 27,477,018
... 34,413,617

... 3,374,650

918,735
... 14,010,930

... 11,130,211

... 3,267,430
... 17,374,699§

7,034

7,765

Railways, Ireland:—

Cavan and Leitrim (coal) .....	7,282

Great Southern and Western

(coal) ......................	5,743

Canals, England: —

Aire and Calder Navigation (coal
and coke) .............................

Birmingham Canal Navigations
(coal and coke)..............
Bridge water Canals (coal, in-
cluding a small quantity of
coke) ......................
Leeds and Liverpool Canal Com-
pany (coal, including a small

■ quantity of coke) ___ ........

Shropshire Union Canal (coal
and coke) ..................
. Staffordshire and Worcester-
shire Canal (coal and coke) ...

Trent and Mersey Navigation
(coal and coke)..............
Canals, Scotland:—

Forth and Clyde Canal (coal and
coke) ......................
Monkland Canal (coal and coke)
Union Canal (coal and coke)...
Canal, Ireland:—

Grand Canal (coal)............

2,064,732 ... 1.920,309

3,448,554 ... 3,528,086

375,304 ...	360,733

751,732 ...	765,000||

16,610	...	16,218

165,190	...	162,204

180,912	...	173,336

116,038	...	136,345

60,309	...	57,950

16,908	...	15,306

Nil	...	161

f Including patent fuel.

I 1,823,231 tons of this quantity were conveyed to
Burntisland Dock and 2,456,375 tons to Methil Docks for
shipment.

§ 1,211,578 tons of this quantity were conveyed to
Burntisland Dock and 1,745,26 i tons to Methil Docks for
shipment.	|| Approximate.

* From Part II. of the General Report on Mines and
Quarries in 1915, edited by Sir Richard Redmayne, H.M.
Chief Inspector of Mines.
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LETTERS TO THE EDITORS.

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The Editors are not responsible either for the statements
made, or the opinions expressed by correspondents.

All communications must be authenticated by the name and
address of the sender, whether for publication or not.
No notice can be taken of anonymous communications.

As replies to questions are only given by way of published
answers to correspondents, and not by letter, stamped
addressed envelopes are not required to be sent.

VEMTILATIOM.

Sirs,—Will you allow me a short space in your paper
to reply to the letter of “ Ventilation.” It would
certainly have been much better had he given more
details of the sizes of his shafts and the size of the
proposed new shaft. However, the difficulty he refers
to can easily be got over, and if “ Ventilation ” cares to
write me direct and send on the particulars referred to
above, I will give him the full benefit of my experience
on this subject, which appears to me similar to that
I have already gone through. I have a case in mind
where increasing the area from 36 ft. to 72 ft. had the
desired effect on the ventilation.

William Leebetter.

Us worth Colliery, co. Durham.

February 26, 1917.

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Coal Trade Benevolent Association.—The annual meeting
of the association was held on Monday in the Coal Mer-
chants’ Society room of the London Coal. Exchange. Mr.
Ernest Oliver presided. The directors’ report and balance-
sheet showed net receipts £7,017, and relief grants £3,451.
Mr. Joseph Shaw, K.C., was elected chairman for the
ensuing year, and Mr. H. Cecil Rickett was elected one of
the trustees, in the place of the late Mr. John Lea Smith.
A bequest of £1,000 was reported from the executors of the
late Mr. F. D. Lambert, and further bequests of £500 each
from the late Mr. F. W. Harris and the late Mr. G. Alder