282

THE COLLIERY GUARDIAN.

February 9, 1917.

CURRENT SCIENCE

Cyanogen from Coke Oven Plants.

Ah American firm, the Bartlett Hayward Company,
is operating a cyanogen recovery plant, based on ithe
Bueb process (Gas Age). The gas, freed from tar, is
treated with a 25 to 30 per cent, solution of ferrous
sulphate, which, with the ammonia and sulphuretted
hydrogen in the gas, extracts the cyanogen, a compound
of ammonia, iron, and cyanogen being formed. The
ferrous sulphate is dissolved in a mixing tank, and the
solution is pumped into a supply tank. The supply to
the washer is adjusted to the quantity necessary to
absorb the cyanogen content of the gas, 3-5651b. of
ferrous sulphate being required per pound of cyanogen
removed. The cyanogen content of the gas, however,
must be taken as an average for the entire carbonising
period, and a slight excess of copperas is, therefore,
given to the washer in order to prevent the escape of
cyanogen during a period when the production may
slightly exceed the average condition determined by the
tests. Average extraction results usually show an
efficiency of slightly more than 95 per cent.

The first reaction occurs in the upper section of the
Feld vertical centrifugal washer, where the copperas
comes in contact with the hydrogen sulphide and
ammonia in the gas, this reaction being—
2FeSb4.7H20 + 2H2S+4NH3 = 2FeS4-2(NHJ2SO4,
or the product secured in this section consists of ferrous
sulphide and ammonium sulphate. As the product of
this reaction passes down through the washer, meeting
the gas during the upward passage of the latter, a
second reaction occurs, or one where the cyanogen com-
bines with the ferrous sulphide in accordance with—
2 FeS + 2NH3 fl- 6HCN = (NH4)2 Fe2 (CN)6 + 2H2S,
the end product being ammonium ferro1-ferrocyanide,
with the liberation of hydrogen sulphide. By the con-
tact between the ammonia, ferrocyanide thus formed with
the hydrogen sulphide and ammonia in the gas, a partial
decomposition of the former takes place—

(NH4)2 Fe2 (CN)fi + H„S + 2 NH3 =
(NH4.)4Fe(CN)6 + FeS,

thus producing some ammonium ferrocyanide and ferrous
sulphide.

The products of these reactions flow from the bottom
of the washer, through a seal, into the cyanogen liquor
storage tank. As some excess iron will always be pre-
-sent in the liquorf and as this iron would discolour the
ammonium sulphate formed during the process, the
liquor from this tank is pumped through a still on its
way to the neutralising tank, this still producing some
ammonium sulphide in accordance with equation—

(NH4)4 Fe (CN)6 + FeS + heat =
(NH4)2Fe2(CN)6 + (NH4,)2S.

From this reaction, it is evident that some of the
ammonium ferrocyanide is again converted into the
double .salt, which passes, with the remainder of the
sludge, through the still and down into the neutralising
tank, while the ammonium sulphide is condensed and
run into the' precipitating tank.

The neutralising tank is a lead-lined, hooded vessel,
provided with a lead steam coil and an agitator. A
small quantity of sulphuric acid (oil of vitriol), diluted
with about three times its volume' of water, is added to
the sludge in this vessel in order to neutralise it, in
accordance with;equation—

(NH4)4 Fe (CN)6 + FeS + H2SO4 =

..	(NH4)2. Fe2 (CN)6 + (NH4)2 SO4 + H2S.

The end product from this reaction gives insoluble double
ferrocyanide of ammonium and iron, plus a solution of
ammonium sulphate, possibly a little ferrous sulphate,
and a trace of free acid, the hydrogen sulphide liberated
being usually conducted to an existing boiler stack.

After the entire sludge has been neutralised and
heated to about 200degs. Fahr., and all single salt has
been converted into the double salt, the liquor is run
into the neutralised liquor tank, whence it is pumped to
the filter presses, where the commercial cake is made.
This cake contains some fixed ammonia, to the extent
of 11’84 per cent, of the ammonium ferro-ferrocyanide
produced; and as 11b. of cyanogen-will produce 1*95 lb.
of this double salt, 1-95 x 0’1184 = 0-231 lb. of
ammonia will be removed from the gas per pound of
cyanogen, extracted; and as the cyanogen content
averages 110 grains per 100 cu. ft. of gas from horizontal
retorts, the ammonia thus removed, per ton of coal car-
bonised, with the production of 10,000 cu. ft. of gas per
ton, will be [(110 x 100) <- 7,000] x 0-231 = 0’363 lb.
The ammonia required to precipitate the FeS04 to FeS,
as per the above equations, will be recovered as ammo-
nium sulphate, and as 0’4363 lb. of ammonia is required
for this purpose per pound of cyanogen extracted, the
amount of sulphate produced per ton of coal carbonised
will be (110 x 100) - 7,000 x (0-4363 x 3-88) - 2-66 lb.

In addition to the sulphate thus produced, a small
quantity is also secured from the fixation of the free
ammonia in the sludge by means of the acid added dur-
ing, neutralisation, a maximum of 0-9 lb. of acid per
ton of coal carbonised being used in the neutraliser; and
a further small amount is due to the fixation of any free
ammonia which may have come over the still, and which
was not taken up in the precipitating process, it being
possible, however, to avoid this latter contingency by
proper' operating conditions.

It, is necessary for this ammonium sulphate solution
to be washed out of the press cake. Consequently, the
cake from the first pressing is placed in the cake wash
tank, where it is macerated with hot water, and then
again sent to the filter presses, the liquor from the first
pressing being run to the precipitating tank, while the
weak liquor from the second pressing is used to make up
a new copperas mixture. The precipitation of excess

AND TECHNOLOGY.

iron is accomplished in the precipitating tank by the
ammonium sulphide from' the still, in accordance with
the equation—

FeS04 + (NH4)2 S — FeS + (NH4)2 S04.

After all excess iron has thus been precipitated, the
liquor is decanted into the sulphate liquor storage tank,
where it is bleared and then pumped up into the lead-
lined evaporator. Here the liquor is evaporated to
crystallisation, the sulphate being removed from the
evaporator, and placed in the centrifugal or hydro-
extractor,« passing thence to the sale drier.

The average saleable product due to this process, per
ton of coal carbonised, will therefore approximate 1’57 lb.
of cyanogen, 0-3631'b. of ammonia, 2’66 I’b. of ammo-
nium sulphate; these figures being based on 2,0001b.
of coal per ton, carbonised in horizontal retorts, with
the production of 10,000 cu. ft. of gas per ton of coal.

Catalysis and Benzene.

In a recent issue of the Journal des Usines a Gaz
(abstracted in Gas World), Mr. A. Mailhe states that, in
its role as true catalytic agent, there exists a very clear
relation with that action which aluminium chloride
plays in the synthesis of the aromatic, hydrocarbons
according to the Friedel and Crafts method. It is
known that when such a compound as methyl chloride,
CH3C1, or ethyl chloride, C2H5C1, or prophylene
chloride, CH2H7C1, is made to react on benzene, for
example, in the presence of aluminium anhydride,
A1C13, the benzene combines with some of the residues,
after the hydrogen has separated in the form of hydro-
chloric acid, by reason of its union with the chlorine of
the halogen derivative. Consequently, when we place
some methyl chloride into a tank containing benzene,
and a certain quantity of aluminium chloride, we get
toluene-' ■

CH3C1 + c6h6 =hci + c6h5ch3.

The aluminium chloride does not seem to enter in this
reaction at all as a contact body, but it is probable that
it plays the role of an active element, giving an inter-
mediate unstable compound which is decomposed very
soon after being formed. It is probable that there must
be formed a. derivative organo-metallic mixture of
aluminium with benzene on which the halogen carbide
reacts in regenerating the aluminium chloride. The
following equations complete the action—

C6H6 + A1C13 = C6H5 A1C19 + HC1.

c6h5 aioi2 + CH2C1 = C6H5CH3 + A1C13.

The regenerated aluminium chloride will react anew on
the benzene, and the same action can be repeated. It
forms then a catalytic agent. Gustavson succeeded in
isolating the compounds made up of the aluminium and
the hydrocarbons. Especially when making the ethyl
chloride to react on benzene he obtained the compound
A1C13, C4Hs, 3CgHg. The toluene can also fix one or
more of the residues in question in the presence of a
catalyser, and will yield xylenes, trimethylbenzene, etc.
But the aluminium chicride is not limited in bringing
about synthetic reactions; it is capable just us well of
producing double reactions, changing complex molecules
to simple molecules, and either bringing about an action
of decomposition or of building up a compound. Thus,
the hexamethylbenzene CG(CHJP, which can be obtained
by the prolonged -action of methylchloride on benzene,
in the presence of aluminium chloride, is decomposed by
the latter when heated in a current of hydrochloric acid.
There are formed successively with the elimination of
methyl chloride, of pentamethylbenzene, of tetramethyl-
benzene, etc., the final products toluene and benzene.

THE “COMBING OUT” OF MINERS.

Representatives of the executive of the Miners’
Federation of Great Britain had a further conference on
Friday of last week with the Home Secretary on the
“ combing out ” of certain classes of miners for military
service. Later in the day the executive council of Great
Britain met, and a letter dealing with the complaints
made by the deputation was submitted.

Dealing with certain minor points, the letter stated
that every effort would be made to carry out the- medical
examination of men with due regard to comfort and
convenience, that certificates of exemption should be
handed over to- the recruiting court only, and not to the
management of the mine, and that managers of mines
had not been instructed to advise all men of military
age to be examined. The letter proceeded re-

Instructions have already been given that men who are
ordinarily employed underground, but at the present time
are temporarily emploved on the surface', are not to be
regarded for the present purpose as surface workers. With
regard to the cases of men who, previously to August 14,
1915, had at some time been employed in mining, but were
actually on that date engaged in some other occupation,
instructions have been given that men who were bond fide
miners, but were temporarily absent from the industry on
August 14, 1915 (e.g., men recovering from illness or’acci-
dent), and who, subsequently, returned to the industry, are
not to be regarded’ as having entered the industry since that
date. The Secretary of State fears that it will be imprac-
ticable to define more precisely the cases which should be
excluded, but he would be willing to instruct the colliery
recruiting court, with whom the decision will rest, to inter-
pret the word “ temporarily ” in a broad way, and it will
be open to any man to submit a claim for the consideration
of the court. As stated at the interview, Sir George Cave is
willing to agree that the decision in regard to the withdrawal
of the certificates of men who over a certain period have shown
themselves persistent absentees shall not operate retrospec-
tively, and further action on the lists now being called for
from the mines will be suspended. He hopes, however, that
the Federation will continue their efforts to diminish absen-
teeism, and that the local absenteeism committees will take

vigorous action in the matter, and be authorised to refer to
the colliery recruiting courts the cases of many men. who,
notwithstanding the efforts of the committee, persist in
absenting themselves from work without reasonable excuse.
With reference to the point raised as to the. application of
section 3 (3) of -the Military Service Act and section 6 of the
Amending Act to surface workers other than men of the
“ barred ” classes, Sir George Cave has arranged with the
War Office that such workers who were engaged in the
industry on and before August 14, 1915, shah be treated on
the same footing for the purpose of these sections as men of
the “ barted ” classes.

After discussion, the executive unanimously agreed to
accept the proposals contained in the statement, and to
express the opinion that the Home Secretary had met
the views put before him by the executive in a very fair
spirit, dealing with all the points in a very satisfactory
manner.

LETTERS TO THE EDITORS.

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.

ABSENTEEISM AND THE BONUS SYSTEM
IN AMERICA.

Sirs,—For years the bonus system has been in force
in the workshops and factories in America with remark-
able results, and, on account of the shortage of labour
and present exceptional demand for coal, it is now- being
tried in the coal mines of the country.

The following method is being given a tri-al by one
company known to the writer. The average for each
miner on the pay roll for each day the mine worked for
the four months’ .period ending November 30, 1916, was
5-65 tons. Bonus shown opposite each item will apply
when the 'average for each miner on the pay roll for each
day the mine works is :—

Method of Arriving at the Bonus.

	Bonus to each	Bonus to each
Tons.	miner on his	company man on
	total tonnage.	his total earnings.
5’75 to 5’84			1 cent	1 per cent.
5-85 „ 5’99			2 cents	2
6 00 „ 6’19	3	,,	3
6'20 „ 6’44	4 „	4
6’45 „ 6-64	5	„	5
6'65 ,. 6’84	6	„	• •	6	„

Bonuses pro rata will be paid on averages in excess of
above.

The bonus will be paid to employees, both miners and
company men, on each fortnightly pay roll, for an
increase in the average tons of coal produced per shift
for each miner on the pay roll. (A company man is a
day-wage man, or salaried official, or employee.)

The average for the mine is raised if the miner works
more days per week, or sends out more coal when he
does work, and the company men keep operations
running smoothly. The average for the four months
Iras been exceeded several times during that period, 'and
team work is expected to keep the output above the
average. The principal object of the introduction of this
system is to prevent, as far as possible, absenteeism.
Assuming that at a certain colliery there are 340 pick
minors and fillers on the pay roll, and 300 of these men
wook, on an average, every day. If the 300 men pro-
duce 7 tons per man per shift, the average for all men
on the pay roll is only 6-1 tons, and the men who stay
away from work prevent the others from receiving the
bonus which they are entitled to. There are several
ways in which the average can be raised and maintained,
and the employer wdll no doubt be glad to pay for his
experiment. Some of these are :—

The removal from the pay roll of the names of all men
who refuse to work regularly; the introduction, of coal-
cutting machines; the introduction of larger capacity
mine trams.

The writer has noticed- that the above bonus system
has caused much enthusiasm among all ranks, from the
under-manager down. He does not claim that it is per-
fect, or that it is above criticism, but it is a step in the
right direction.	Samuel Dean.

Delagua, Colorado, U.S.A.,

Jan. 9, 1917.

SAFETY FIRST.

Sirs,—Your review of Mr. Gower’s book on safety
appliances does well to emphasise the facts that safety
appliances are extremely profitable to users, even when
judged only by contrast with insurance premiums, and
that such are essential to business efficiency in mining.

In the States, the efficiency movement has been
popular during the past 20 years. Its object is elimi-
nation of costs due to wastage of substance, time, and
effort. It leads to concentration of energy, expense, and
time for profit to the business. Personal injury is found
to be business wastage—waistage of profits, as well as
unnecessary suffering—and the use of safety appliances
is found to be highly profitable, besides preventing
'Suffering. So that whether we adopt safety appliances
from sentimental or business motives, the result is the
same—both safety and profit to the mining operators.

“ Safety first ” is essentially a practical business
maxim for shareholders and officials, as well as for
workmen. The working costs of safety appliances are
very small compaired with their earning and profit' values
in mining. Especially is this true in haulage and shaft
operations, in which the use of direct safety appliances
will generally be found highly profitable.

February 7, 1917.	A. Hanley.