October 4, 1918.

THE COLLIERY GUARDIAN

705

140 tons of coal were passed through the plant, about
100 tons of which was Franklin County mine run
crushed to pass through a 2 in. round hole shaker
screen. The other coals tested, in lots ranging from
4 to 12 tons, comprised Harrisburg and Eldorado in
Saline County, Ill.; Indiana 4th Vein from the J. K.
Dering mine, Clinton, Ind.,; Indiana No. 5 from
Grant Mine No. 4; and Indiana No. 5 from Knox
County.

The plant comprised one oven or retort, together
with the usual condensing and scrubbing apparatus
for the distillate gas, and other necessary machinery
and appliances.

The oven was horizontal and rectangular, about
60 ft. long, 4 ft. high and 20 in. wide. At each end
was a double dobr lock, one serving for the admis-
sion and the other for the withdrawal of the con-
tainers carrying the coal, without admitting any
substantial amount of air. These locks were of suit-
able length to hold one container; they were not
heated, nor was a space of the same length as the
lock immediately inside of it. The remainder of the
retort was supplied with down draught flues, each of
which led to a large off-take flue in the base of the
oven, and thence to the stack.- The flues were about
1 ft. square in their inner dimensions, and were laid
with ordinary rectangular silica brick, as tongued and
grooved brick in interlocking shapes could not be
obtained for many months. As the volume of clean
gas yielded by the low-temperature process is insuffi-
cent for heating the oven, provision was made to
supply city gas for the additional heat necessary; in
the commercial plant, producer gas will be supplied
for this purpose.

A track was laid through the oven with 16 lb. steel
rail, 11 in. gauge, to carry the containers. These were
introduced at intervals into the charging end, each
successive container pushing those which had preceded
it. When the retort was filled, a finished container
would be discharged whenever a fresh one was in-
serted. The train of containers was pushed by a
hydraulic ram, and they were charged with coal, and
(the coke was discharged from them manually. In
the commercial plant the pushing will be done by an
electric ram, and the charging and discharging will
be mechanical.

The design of |hese containers was the central
feature of the process. Those used in the experi-
mental plant were about 4 ft. long, 4 ft. high and
12 in. wide. Partitions, 12 in. apart, divided each
box into four sections, each 12 in square. Each box
was placed on a cast-iron truck mounted on four
cast iron wheels. When the truck and box were
removed from the oven, the box was lifted off, the
coke discharged, the box replaced on the truck and
returned to the other end of the oven for re-charging.

One of the principal purposes of this form of con-
tainer was to afford means by which 'the heat could
be quickly conveyed through the mass of coal. Expe-
rience with the high temperature by-product oven
has shown that when heat is applied only to the side
of the charge, the progress of the coking is very slow,
probably only | in. per hour.

It is impracticable to make a semi-coke of sub-
stantially uniform volatile content unless special
means are employed for conveying the heat to the
centre of the charge more quickly than is possible
by means of a heated side wall only, because if the
side wall temperature is not raised above 1,000 degs.
Fahr., the progress of the coking toward the centre
will be prohibitively slow; indeed, it has proved im-
practicable to convey the heat at that temperature
through 10 in. of coal. If the heat is raised above
1000 degs., by the time the tarry volatiles are all
driven off at the centre of the charge, the volatile
contents of the coke on the outer side will be greatly
reduced, thus giving a coke of widely varying
character. Furthermore, the higher temperature will
cause a proportionate decrease in the valuable light
oils and a corresponding increase in pitch; the per- .
centage of coke also will be decreased. There will
be an increase in gas, but it will fall far short of
compensating for the losses mentioned.	’

The first container boxes were made of sheet steel,
and were divided into four compartments each 12 in.
square. It quickly developed that this column was too
large for short-time coking with a reasonably uniform
volatile contents. Additional compartments were
then put in some of the boxes, while in others pipes
of varying diameters were placed in the centres of the
large compartments. Both of these expedients pro-
duced usable coke.

A cost iron box also was used; the shell and par-
titions were } in. thick, and the compartments varied
from 4 to 8 in. in width. This cast iron box showed
great superiority over all other forms, and proved
eminently satisfactory for the purpose. The compart-
ments were tapered slightly, so that by the time the
boxes reached the open air the temperature had been
reduced enough to cause a slight shrinkage and the
coke slipped out of the compartments without diffi-
culty. It showed no tendency whatever to cling to
the metal.	’	„

Characteristics of Semi-Coke.

The semi-coke thus produced proved a most satis-
factory fuel for all general purposes. Although the
retort had only side wall heat, it produced a coke
practically homogeneous in structure and volatile
contents. By keeping the charge in the heat long
enough, a hard coke with practically no volatile
contents could be produced, or by withdrawing the
charge as soon as it was fused to the centre, the
coal could be changed into the form of coke while
but little of the original volatile contents had been
removed. Experience indicates that the ideal fuel for
general use is obtained by leaving about 18 per cent,
of volatile matter in the coke. This gives a satisfac-
tory yield of coke, while at the same time practically
all the volatile-producing oil or tar has been removed
and the coke thereby rendered smokeless. Using
compartments of suitable width, the coke is uniform
in structure and has sufficient strength to permit
sizing and handling. The specific gravity is some-

what less than that of hard coke, but not enough
so to be a practical objection. The breeze and fines
burn satisfactorily, eitner by themselves or with the
coarse sizes; in tact, the behaviour in the fire-box
in that respect is quite similar to that of bituminous
coal. It ignites as readily as bituminous coal. The
fire is easily controlled, and was successfully banked
for eight to ten hours in house furnaces during severe
winter weather. It burns with a short, bright, clear
blaze, and is clean to handle and fire.

An eight-hour test of the semi-coke made from three
different kinds of coal was made on a switch engine
in one of the large railroad yards in Chicago. The
coals were Franklin County, 111., Indiana Vein No. 5
from north of Terre Haute* and Indiana Vein No. 5
from Knox County. In clearing up the pile from
which this tender load was taken, all of the fine stuff
was gathered up with the coarse, so that there was
a large percentage of it in the tender load, which m
proportion of coarse and fine resembled mine run coal.

There was a light coal fire in the locomotive, and
on this the semi-coke was started. It steamed rapidly
from the start and made no smoke throughout the
test. The amount of cinders thrown from the stack
with a heavy exhaust was but a small proportion of
the amount coming from bituminous coal. The semi-
coke steamed rapidly enough to make it unnecessary
to use the steam blower when the exhaust was off, as
is done to lessen the smoke when bituminous coal is
used; this effects a substantial saving of coal. The
engine did its regular yard work for about four hours,
the crew being changed at the third hour. By this
time a thin clinker had formed, which, however, was
readily removed during the noon hour. Another thin
clinker was formed and removed during the afternoon,
but some coal, of which there was some at the bottom
of the tender, had been fired on top of the semi-coke
before this happened. The engineer of tests of the
railroad stated that this clinkering probably resulted
from the mixing of semi-coke made from three
different kinds of coal and from the excessive amount
of fine stuff, and it was agreed that the semi-coke had
satisfactorily shown its adaptability for locomotive
use without material change in the fire-box.

In regular practice, a semi-coke made from one
kind of coal will clinker less than the coal from which
it is made. This is because the semi-coke burns up
without permitting the lumps to break down or melt;
there is therefore a better circulation of air through
the fire bed than with coal. In regular practice there
also would be a great deal less fine stuff than was
in this tender load.^ In a plant equipped entirely
with casting boxes, the plant run of semi-coke would
contain a very small percentage of fine stuff. From
his observation in the experimental plant, Mr.
Garland estimates this at less than 10 per cent.

Volatile Products of Distillation.

In the operation of the experimental oven it was
demonstrated that it would not be possible to use a
brick wall between the side flues and the containers,
and at the same time make a practically complete
recovery of the oil and gas in the coal. This was
partly due to the small amount of gas | to 1 cu. ft.
per pound of coal, obtained in the low temperature
process, as compared with 5 to 6 cu. ft. in the high
temperature process. A small air leakage, such as exists
in the high temperature ovens, would tfierefore produce
disastrous results. Even in high temperature ovens
there is more or less trouble in keeping down the
percentage of carbon dioxide in the gas. In the ex-
perimental oven the use of plain silica brick instead
of special interlocking brick increased the leakage
materially, although special precaution was taken in
laying up the brick and in coating the interior of
the oven with special high temperature cement.

The quantitative determination of gas and tar was
therefore impossible with this oven. These factors,
however, have been demonstrated repeatedly, not only
by Prof. Parr, for practically every coal mined in
the State of Illinois, but also by numerous others.

For the commercial oven a cast iron retort will be
used, which will be lined on the flue side with silica
brick. This retort is ribbed to prevent warping, and
is fixed only at the centre, leaving the ends free to
expand. Since the temperature within the oven does
not exceed 1,000 degs. Fahr., this will not only
ensure a gas-tight construction, but the retort will be
considerably more permanent than a brick structure,
and will cost less for maintenance than brick retorts
of this form.

The light tar produced by the low temperature
process is a liquid having the consistency of heavy
cylinder oil. Its significant characteristics,’ as dis-
closed by Prof. Parr’s work, are: First, the large
percentage of the light fraction cut at 210 degs. Cent,
(about 18 per cent.); second, the large percentage
of the middle fraction (about 52 per cent.) and the
high percentage of the tar acids therein; third, the
very low proportion of pitch (about 30 per cent, as
compared with 65 per cent, or more in the heavy
high temperature tar), the low melting point of this
pitch, and its low percentage of free carbon.

Taking Franklin County, Ill., coal as a basis, the
results of operation at the experimental plant indi-
cated that the products of low temperature distilla-
tion will be about 77 J per cent, of semi coke having
18 per cent, volatile combustible matter, and about
25 gallons of light tar and oil per ton of coal. There
will also be a small amount of ammonia, but since
the nitrogen in the coal, which is the source of
ammonia, does not leave the coal freely until the
temperature is considerably above 1,000 degs. Fahr.,
the greater part of the nitrogen remains in the semi-
coke ; if this product is then made into producer
gas in a by-product plant, a very large recovery of
the ammonia may be* made. Treated in this way,
the recovery from Franklin County coal would be
about 100 lb. of sulphate of ammonia per ton of coal.
This assertion is based upon data furnished by
C. W. Tozer regarding his experiinents with English
coal closely resembling that of Franklin County. In
the high temperature non-volatile coke plants the

nitrogen is all driven off the coal, but only the lesser
part of it is recoverable as ammonia, because the
temperature of the oven is so high that the greater
part of the nitrogen does not combine with hydrogen,
or, if such a combination is made at first, it is later
broken up before it can be recovered.

Based upon experience at our experimental plant,
the heating period required with the casting con-
tainers will not exceed eight hours, and it is probable
that this may be reduced. The length of time re-
quired depends upon the greatest distance which it is
necessary for the heat to travel through the coal. A
shorter period could be attained by reducing this
distance, but if it is too greatly shortened, the result
might not be compensatory, by reason of structural
and other considerations.

High v. Low Temperature Distillation.

Ample data were secured, from the operation of the
plant, upon which to base enlarged and perfected
designs for a commercial plqnt, and to furnish a
sound basis for estimating the cost of installing and
operating it. This has been carefully worked out by
Mr. Garland and the writer, and the results are very
attractive as to earning power. The plant will cost
considerably less than a high temperature plant of the
same capacity, and the products will yield a larger
return per ton of coal. Franklin County coal, which
has a natural moisture content of about 8J per cent.,
will yield 12 to 15 per cent, more semi-coke by the
low temperature process that can be derived from it as
hard coke by the high temperature process. There
will be at least double the amount of tar and oil,
and commercial investigations indicate that its value
per gallon will be several times as great. The high
temperature process will yield several times as much
gas as the low temperature process, but the surplus
gas is always sold at a very low price. The high
temperature process also has some advantage in the
greater amount of ammonia produced, but this also
is more than offset by other considerations. The
opportunities for commercial development of the low
temperature process seem to be very great.

SUGGESTED RULES FOR USE IN
RESCUE WORK.

Appendix I. of the Report of the Mine Rescue Appa-
ratus Research Committee contains the following
suggested code of rules for the conduct and guidance
of persons employed in rescue work.

Manager or Principal Official for the time being at
the Surface of the Mine.

1.	On receiving information of any occurrence likely
to require the service of rescue apparatus, the follow-
ing steps shall be taken by the manager or, in his
absence, by the principal official present at thfe

♦ surface: —

(a) Telephone to the central rescue station. Inform
the instructor of the character of the occur-
rence. State whether assistance will be needed
from rescue brigades other than the permanent
station corps or the brigades attached to the
mine;

(&) Summon the trained men attached to the mine;

(c)	Telephone for medical assistance;

(d)	Telephone to the inspector of mines;

(e)	If necessary, communicate with the police

station.

2.	No person shall be allowed to enter the mine or
the part of the mine which is unsafe for the purpose
of engaging in rescue operations unless authorised by
the manager or, in his absence, by the principal
official of the mine present at the surface, and during
the progress of such operations a person or persons
shall be stationed at the entrance of the mine and
required to keep a written record of all persons enter-
ing and leaving the mine. Only men trained with the
apparatus shall be permitted to enter the mine for the
purpose of using rescue apparatus.

3.	Prior to sending a brigade underground, clear
instructions shall be given to the leader of the brigade
as to where it shall go and what it shall attempt.
Unless the leader is personally thoroughly familiar
with the roadways in question, the route shall be
marked on a tracing, which the leader shall take with
him into the mine.

4.	A qualified medical man shall be in attendance
at the mine wherever rescue parties are at work,
unless in the opinion of the manager and inspector of
mines that course is unnecessary.

The doctor, when present, shall examine every man
engaged in rescue work before permitting him to go
underground for a second spell of that work. ’

5.	As soon as possible a base or bases shall be estab-
lisher in fresh air, but as near to the irrespirable zone
or zones as safety permits. Each such base shall, if
possible, be connected by telephone to the surface or
to the shaft bottom. Whenever men are at work
beyond the base there shall be stationed at the base
at least the following: (a) Two men, of which at
least one should understand rescue appliances and
first aid; (b) a spare brigade with rescue apparatus
and ready for immediate service; (c) one or more
oxygen revivers, stretchers and birds.

Captain or Leader of a Rescue Brigade.

6.	The leader shall not permit the brigade to go
underground until he has received clear instructions
from the manager or from the person acting on the
manager’s behalf, and unless the leader knows the
route thoroughly, he shall take underground a plan
on which the route is clearly marked.

7.	The leader shall not engage in manual work. He
shall give his attention solely to directing the brigade
and to maintaining its safety. He shall examine the
roof and supports during the outward journey, and
if there is any likelihood of a fall he shall not proceed
until the brigade has made the place secure. He shall
not take the brigade through any passage less than
2 ft. high and 3 ft. wide, except in a case of urgent
necessity.