IMPROVEMENTS IN THE MANUFACTURE OF SODA AND IN APPARATUS APPERTAINING THERETO
Year: 1883

page_text: LETTERS PATENT to Ludwig Mond of Winnington Hall Northwich in the
county of Chester for an Invention of "IMPROVEMENTS IN THE MANUFACTURE
OF SODA AND IN APPARATUS APPERTAINING THERETO
PROVISIONAL SPECIFICATION left by the said Ludwig Mond at the
Office of the Commissioners of Patents on the 9th February 1883.
LUDWIG MOND of Winnington Hall Northwich in the County of Chester,
"IMPROVEMENTS IN THE MANUFACTURE OF SODA."-AND IN APPARATUS APPERTAINING
THERETO
This invention relates chiefly to the drying furnacing and cooling of the salts.
The bicarbonate of soda produced by the Ammonia Process contains a quantity
of Ammonia which if it was dried in the ordinary way would be lost. 1 employ
therefore a circular drying chamber with a tight cover and having a vertical
central revolving shaft suspended from above through a luted aperture in the
centre of the roof. Upon arms from this shaft at varying distances from the
centre I form dogs or lugs projecting downward. Each of these dogs fits loosely
into a hole in a heavy loose plough or scraper there being a separate plough for
each dog. The bottom of the chamber is formed of plates so constructed that each
plate and the whole bed shall be free to expand yet be salt tight. Thus it could
be formed of plates with overlapping flanges in one direction and grooves and
tenons in the other, a loose flat bar of iron forming in each case the tenon, or in
place of grooves and tenons a long narrow plate could be placed below each joint
of the series going in one direction, the flanging being in the opposite direction, or
two sets of plates could be used breaking joint with each other, or lastly the plates
could be flanged on two sides to fit into recesses in the two sides of their
neighbours. The overlapping flanges buff joints or grooved edges whichever may
be used, are so shaped being bevelled upwards as not to get choked by the
material and thus the whole bed as well as each plate can freely expand and
contract,
The gases from a furnace pass below these plates heating the bottom. The
ammonia and part of the Carbonic Acid having been driven off by the salt being

page_text: stirred over these hot plates a door in the hood is opened and the salt pushed
through a shoot connecting the closed chamber with a reverberatory furnace
standing beside it onto the bed where it is finished in the usual way. Fresh salt
is then introduced into the closed chamber by the feeder hereafter described and
the process goes on as before.
As the opening of the closed chamber to admit a fresh charge of bicarbonate
would involve the escape of the ammonia fumes present in the furnace I introduce
the fresh material through a hopper in the orifice at the bottom of which a shaft
armed with long teeth or pins revolves, this orifice is near the centre of the roof.
These aforesaid teeth or pins project say at angles of 90 degrees with each other
from the shaft or centre, only one or two being in the same plane with each other
and in the same side of the shaft. Projecting from the sides of the orifice between
the paths of the revolving teeth or pins are preferably horizontal cross bars curved
or cut out at the centre so as to just clear the revolving shaft. The teeth fixed on
this shaft draw down the bicarbonate and press it in a pretty regular stream
through the interstices between the stationary bars. The bicarbonate filling the
hopper above prevents the gases from escaping during the operation of charging.
If desired the reverberatory furnace can be dispensed with-and-the-salts can be
finished to the desired degree in the closed chamber alone. In this case the
operation can be carried on continuously.
To cool the soda ash I place it onto a slowly revolving endless belt, and place
just over the belt a peculiarly shaped plough preferably formed of bar iron which
evenly spreads the soda ash over the belt. It falls off at the further extremnity
into a hopper. The belts are made of wire cloth painted over with the solution of
a salt which is not acted upon by heat or by dry carbonate of soda, such as silicate
of soda.
SPECIFICATION in pursuance of the conditions of the Letters Patent, and of
an Order of the Lord Chancellor, filed by the said Ludwig Mond in the Great
Seal Patent Office on the 14th August 1883.
_LUDWIG MOND, of Winnington Hall, Northwich in the County of Chester
"IMPROVEMENTS IN OR APPERTAINING TO THE MANUFACTURE OF SODA
"
This invention relates chiefly to the drying, furnacing, and cooling of the salts.
The bicarbonate of soda produced by the Ammonia Process contains a quantity
of ammonia, which if it were dried in the ordinary way would be lost. To dry it
therefore I have invented special plant, which is best described by aid of the
accompanying drawings of which :-
Figs. 1 and 2 are vertical sections of the furnace and concomitant apparatus,
taken at right angles to each other, and
Fig. 3-a plan.
T

page_text: столия расще
Fig. 10 side elevation, and
Fig. 11-plan of apparatus, applicable for cooling soda ash and other similar
heated salts.
Referring to the first six figures, A. is an oven or closed chamber with its floor B
heated by a flue or series of flues C, C, below, D a shaft passing through a luted
aperture in the roof of oven, and driven by ordinary bevel gear E, E¹. F feeding
apparatus, described more fully hereafter in reference to Figa. 7, 8, and 9.
G tubular crosshead keyed, bolted, or otherwise fixed to shaft D, having a series of
projecting pins H, H. I, I are heavy metal shoes or ploughs fitting loosely on
pins HH, instead of being fixed rigidly to the arm, and driven round over the
floor B by means of shaft D, the shoes of each arm being, as is usual with
ploughs or stirrers in furnaces, made to follow different paths. When working
continuously, these ploughs can be formed with their beaks between the centre of
the pan and the axis of the plough, and held by two pins instead of one, so that
they shall be held in one position relatively to the shaft, and gradually move the
material from the centre to the outside. J is a passage closed by two doors or
dampers leading into an ordinary reverberatory or calcining furnace K, where the
material dried in the oven A can be calcined. The ammonia and other gases given
off in oven A, are taken by a pipe, not shown in drawing, to condensers, or passed
through sulphuric acid so as to recover the ammonia. The object of this peculiar
arrangement of two furnaces with double valved passage between, is to retain the
ammonia which would otherwise be lost while the salt is being dried on the beated
floor. By opening only one door at a time, or shoving the salt through while both
are open and keeping the passage choke full all the time, the material can be passed
without the gases escaping in any considerable amount. The part between the
two doors can always remain full of solid material, and thus form an additional
seal while working. When the apparatus is worked on the continuous system, the
inclination of the passage J, and the pressure of the ploughs always pressing the
material to the circumference, causes the material automatically, and practically
continuously, to be discharged into furnace K, but when worked on the intermittent
plan, the ammonia, and part of the carbonic acid having been driven off by the
salt being stirred over these hot plates, a door in the hood is opened, and the salt
pushed through a shoot connecting the closed chamber with a reverberatory
furnace standing beside it, onto the bed, where it is finished in the usual way.
Fresh salt is then introduced into the closed chamber by the feeder hereafter
described, and the process goes on as before.
The great difficulty which has probably prevented the use of heated floors for a
similar purpose to this, is the variable expansion and contraction of the floor which
is constantly going on, and thus the apparent impossibility of keeping said floor
gas tight.
I effect this object in the following manner. I form the floor of large iron plates
every one of which is free to move independently of the rest, while to keep the
floor tight, overlapping or tongued joints are used, the joints running one way,
being so arranged as not to interfere with the joints running the other; I also
round or bevel off the upper edges of the plates to prevent material getting
wedged in the cracks. There are various ways of making joints on this principle;
one which I believe will be found as good as any, I have shown in the drawings. In
this the plates are flanged in one direction, and fitted with a loose flat bar of iron
as a tenon, and grooved in the other; some of the other plans set forth in the
provisional specification will do almost equally well. In feeding this furnace or
oven, as in emptying it, it is very desirable to avoid the escape of ammonia as
much as possible. I have therefore for this purpose invented a peculiar arrange-
ment of feeding apparatus, set forth in figures 7 to 9 inclusive.
In these, L is a hopper. M bars placed across the opening below the hopper

page_text: transversely, and curved in the middle, so as to enable shaft N to lie clear of them,
yet with its centre line on a level with their surface, O, O, arms on shaft N, which
when horizontal are parallel with the bars M. It is not necessary however that
they should be exactly parallel or the surface of the bars and the axis of the shaft
exactly coincident, but the arrangement described is best. It will be noticed that
there is only one arm between each pair of bars. This as it revolves round, draws
the material in between the bars, and as the bars are arranged to alternate with
each other, a nearly constant stream of feed is the result. A sufficient layer of
fresh bi-carbonate is kept in the hopper to prevent the escape of the ammonia in
that direction.
If desired, the reverberatory furnace can be dispensed with, and the salts can be
finished to the desired degree in the closed chamber alone.
usual
The figures 10 and 11 show the belt for cooling the soda ash. In these, Q is
the belt caused to slowly revolve round pulleys R R¹, and sustained as
with very heavy belts, by carrying rollers S S. T is an ordinary hopper
delivering the hot soda ash onto the belt. U is a plough or framework of bar iron
preferably with sides a little deeper than the rest for evenly spreading the material
on the belt. This plough is firmly secured to stationary framework. The material
arriving at the pulley R. in a cooled state, drops into a hopper or other receptacle-
or onto a carrier. The belt is made of wire cloth, painted over with a solution of
any salt which is not acted on by heat or by dry carbonate of soda. Silicate of
soda will answer as well as any that I know. Belts have been proposed and used
for drying, but not to my knowledge for the purposes described, or accompanied
with a plough for spreading.
Having now described my invention and the best mode known to me of carrying
it into effect, I claim as my invention secured by the letters patent :—
The manufacture and use of the various improvements in apparatus or plant, for
the manufacture of soda substantially as and for the purposes described.
In witness whereof I the said Ludwig Mond have hereunto set my hand and
seal this third day of August in the year of our Lord one thousand eight hundred
and eighty three.
Witness
WP THOMPSON
Patent Agent
Liverpool & London.
LUDWIG MUND (L.S.)