March 30, 1917.

THE COLLIERY GUARDIAN.

623

stroke is completed, and the hand lever must be held
over by the operator during this period. Immediately
the hand lever is released, it is automatically brought
back to the exhaust position, and the inter-locking gear
is re-set by means of the balance weight and connect-
ing levers shown between the -two cross girders at the
cage end of the platform, the gear remaining locked in
this position until released again by the cage.

The required water pressure of 1251b. per sq. in. is
obtained by means of a set of three-throw electrically-
driven pumps, with a capacity of 20 gals, of water per
minute, shown in fig. 6. This pump delivers the water
through the accumulator (fig. 5), which consists of a cast
iron ram and cylinder, supporting a casing built up from
wrought iron plates, and holding about four tons of
weighing ballast, the whole being supported on a massive

trabions and particulars of the plant—to the instructions
and designs of Mr. Hugh Bramwell, the engineer and
agent of the Great Western Colliery Company Limited,
and Mr. J. W. Davison, the chief mechanical engineer
of the company.

THE RECOVERY OF BENZOL

Fig. 3.—Elevation.

I _

Side Elevation.

Elevation,

Front Elevation.

Fig. 5.—Accumulator.

Plan

Elevation of Top Landing

of One Side of iop Landing

Fig. 4.—Plan.

FROM GAS.*

By F. W. Sperr, Junr.

One of the most noteworthy achievements in
American chemical industry during the last two years
has been the rapid development of the recovery of
benzol from coal gas. Associated principally with the
manufacture of by-product coke, the business of
recovering benzol in America had previously lagged
behind the parent industry, which was already begin-
ning to make striking progress three or four years
before the outbreak of the great war. The lag was
due, partly, to a seeming lack of real demand for the
material; partly to the abundance of petroleum, and
partly, also, to the groundless fear that the opera-
tions necessary for the recovery of benzol would add
too many complications to the manufacture of by-pro-
duct coke.

Thus, at the close of 1913 there were about 16 plants
in the United States making light oil from coke oven
gas. Most of the product from these plants was used
for the enrichment of illuminating gas, leaving a com-
paratively small amount of material for other purposes.
There were only two or three small plants for the
manufacture of pure benzene, toluene, etc.

Even at that time, however, there were signs that
the importance of the recovery of benzol was gaining-
recognition, and it is likely that the advancing price
of gasolene would soon have led to a large extension
of the industry, even without the stimulus of war
prices.

From the close of 1914 to the summer of 1915 the
prices of benzol products rose with the cessation of
foreign supply and the ever increasing necessities of
the munition business, until pure benzene commanded
over 80c. per gal., and toluene was sold as high as
7 dols. per gal. The response was rapid. The first
complete modern plant for the large-scale production
of pure benzene and toluene was put into operation in
May 1915, and the total production of benzol products
in the United States in that year rose to over
22,000,000 gals.—more than twice as much as had been
produced the previous year.

At present there are about 40 benzol recovery plants
in operation in connection with by-product coke
plants, having a capacity of approximately 30,000,000
tons of coal per annum. Making due allowance for
the facts that a number of these plants scrub only part
of their gas, and that part of the benzol is imme-
diately used for enrichment, a conservative estimate
would place the present annual light oil production at
not less than 40,000,000 gals. Three of these plants
are now being enlarged, and eight new plants are in
course of construction. The completion of this new
work will bring the annual production of light oil up
to nearly 50,000,000 gals.

It should be noted that the increase of output has
been almost altogether in the production of pure pro-
ducts ; the amount of unrefined benzol now being made
is probably actually less than was made in 1914. It



Fig. 6.—Pumps.

The slide rails which support the ram heads are of
cast iron, accurately machined their whole length, and
secured to the cross -girders. After the out-stroke is
completed, the rams are drawn back by means of balance
weights attached to wire ropes running over guide
pulleys, as shown in the plan, fig. 2. The balance-
weights are of cast iron, and are provided with slots
suitable for running on j- in. diameter guides to prevent
swinging. These balance weights work in a pit below
the landing.

cast iron foundation plate. The accumulator is pro-
vided with a relief valve and operating gear for auto-
matically controlling the working of the pumps.

The time occupied in decking the cages is one minute,
and the arrangement of the machinery is so automatic
that only one movement of the hand lever by the
operator is required to set it in motion.

The whole of the machinery has been manufactured
and supplied by Messrs. George Fletcher and Company
Limited, of Derby—who very kindly supplied the illus-

appears probable that at: least 80 per cent, of the pre-
sent production is re-distilled for the preparation of
pure benzene and toluene.

Uses of Benzol.

The question is frequently asked: ‘ 1 What will
become of this vast production of benzol after the
war?” It must be remembered, in the first place, that

* From a paper read before the American Institute of
Chemical Engineers.