IMPROVEMENTS IN THE TREATMENT OF SULPHATE OF AMMONIA FOR OBTAINING THE AMMONIA IN THE FREE STATE AND UTILIZING THE SULPHURIC ACID
Year: 1884

page_text: We EUSTACE CAREY HOLBROOK GASKELL the younger and FERDINAND HURTER
all of Widnes in the County of Lancaster Alkali Manufacturers do hereby declare.
the nature of said Invention for "IMPROVEMENTS IN THE TREATMENT OF SULPHATE
OF AMMONIA FOR OBTAINING THE AMMONIA IN THE FREE STATE AND UTILIZING
THE SULPHURIC ACID " to be as follows:-
In carrying our Invention into effect we mix intimately (either in solution or by
grinding) the Sulphate of Ammonia with one or more equivalents of Sulphate of
Soda-If the Salts be in solution we evaporate to dryness and heat the dry salts
to a temperature sufficient to decompose the Ammonium Sulphate the Ammonia
passing off as free Ammonia, the Sulphuric Acid remaining combined with Sodium
Sulphate forming Hydrogen Sodium Sulphate. The reaction is incomplete unless
a current of Steam be passed over or through the semifluid Salts.
We conduct this process in iron vessels heated from outside and provided with
apertures for admitting steam and for the escape of the ammonia vapors We
condense the Ammonia vapors by means of water.
The residual Hydrogen Sodium Sulphate we utilize in any well known manner
either for the production of Sulphuric Anhydride, or we heat it with Common salt
for the purpose of obtaining Hydrochloric Acid and neutral Sulphate of Soda.
Dated this 25th day of January
1884
J. HENRY JOHNSON,
47, Lincoln's Inn Fields, London, W.C.,
Agent for the said Eustace Carey, Holbrook Gaskell
the younger, and Ferdinand Hurter.
J. HENRY JOHNSON,
47, Lincoln's Inn Fields, London, W.C.,
Agent for the said Eustace Carey, Holbrook Gaskell
the younger, and Ferdinand Hurter.

page_text: We, EUSTACE CAREY, HOLBROOK GASKELL the Younger and FERDINAND
HURTER all of Widnes in the County of Lancaster Alkali Manufacturers
do hereby declare the nature of said invention for IMPROVEMENTS IN THE
TREATMENT OF SULPHATE OF AMMONIA FOR OBTAINING THE AMMONIA IN THE
FREE STATE AND UTILIZING THE SULPHURIC ACID, and in what manner the same
is to be performed, to be particularly described and ascertained in and by the
following statement:―
Our Invention has for its object to treat Sulphate of Ammonia in an improved
manner so that the Ammonia is obtained in the free state and the Sulphuric acid is
utilized.
According to our Invention we mix intimately the Sulphate of Ammonia with
one or more equivalents of Sulphate of Soda. This may be effected in any suitable
manner such as by solution or by grinding. If, the Salts be in solution we
evaporate to dryness. We heat the dry mixed Salts to a temperature sufficient to
decompose the ammonium Sulphate, the ammonia passing off as free ammonia, the
Sulphuric acid remaining combined with Sodium Sulphate forming hydrogen
Sodium Sulphate, or bisulphate of Soda. The reaction is incomplete unless a
current of Steam is passed over or through the semi-fluid Salts and we therefore
cause a current of Steam to be passed over or through them. We find that the
operation is much improved and the action quickened if the Steam be superheated,
but it should not exceed a temperature of 850° Fahrenheit.
We conduct this process in suitable vessels (which should be of cast iron) heated
from the outside and provided with apertures for admitting Steam and for the
escape of the ammonia vapours which vapours may afterwards be condensed by
means of water in the ordinary way.
The residual hydrogen sodium Sulphate we utilize in any well known manner
either for the production of Sulphuric anhydride or we heat it with common Salt
for the purpose of obtaining hydrochloric acid and neutral Sulphate of Soda.
And in order that our said Invention may be fully understood we shall now
proceed more particularly to describe the same and for that purpose shall refer to
the several figures on the annexed Sheet of Drawings, the same letters of reference
indicating corresponding parts in all the figures:
In carrying our Invention into effect we mix intimately either in solution or by
grinding or in any other convenient manner one equivalent (say sixty six parts)
of ammonium sulphate with one equivalent of Sodium Sulphate or to insure
sufficiency of Sodium Sulphate with rather more than one equivalent, say Seventy
five parts of Sodium Sulphate. If the mixture is made by dissolving the said
Salts, we evaporate the solution to dryness in suitable evaporating apparatus in
order to obtain the mixture of Salts in a dry or nearly dry condition.
The dry Salts we heat gradually to fusion in suitable apparatus; when at a
temperature of about 500° Fahrenheit a decomposition begins by which free
ammonia and hydrogen Sodium Sulphate are produced. The reaction is
represented by the following chemical equation, (N. H 4), S, O₁ + Na, S, O₁ =
2 Na H, S, O + 2, N, H 3.
14
In order to hasten the reaction we raise the temperature gradually to from 700°
to 850° Fahrenheit and we agitate the fused mass.

page_text: As soon as the temperature of the Salts is sufficiently elevated we introduce
Steam into the vessel in which the Salts are being fused; and the Steam may
simply pass over or may be caused to pass through and thus agitate the
fused mass.
The ammonia which is set free by this treatment passes away together with the
Steam and is conducted by suitable pipes into suitable condensing apparatus so that
the Steam may condense and the ammonia gas be utilized for any of the purposes
for which ammonia gas is required.
When all the ammonia has been driven off, the Sulphuric acid remains combined
with the Sodium Sulphate so that the residue in the apparatus consists of
hydrogen Sodium Sulphate in a fused condition. By opening suitable apertures in
the apparatus, the fused Salt will flow out and may then be utilized either for the
production of Sulphuric anhydride or for the manufacture of bydrochloric acid as is
well understood.
In order to carry out successfully this Invention regard must be paid to the
following points.
When a rapid current of Steam is passed over or through a heated mixture of
ammonium Sulphate and Sodium Sulphate, a considerable quantity of the
ammonium Sulphate is carried away as such by the current of Steam, particularly
when the Salts have not been mixed intimately. It is therefore advisable to
admit very little or no Steam at the commencement of the operation. After fusion
has occurred Steam may be applied more freely.
At the temperature at which the ammonia is driven off from the fused Salts,
hydrogen Sodium Sulphate is apt to give off water and form Sodium pyrosulphate.
This Sodium pyrosulphate immediately reacts upon any ammonia which may still
be in the mass producing nitrogen, water, Sulphurous anhydride, and Sodium
Sulphate, whereby a loss of ammonia is incurred.
The introduction of Steam prevents the formation of this pyrosulphate and the
consequent decomposition and loss of ammonia. Moreover if the ainmonia gas is
not removed from the apparatus as fast as it is liberated, the reaction proceeds very
slowly and remains incomplete. The Steam by removing the ammonia gas from.
the apparatus hastens the reaction and renders its proper completion possible.
The employment of Superheated Steam still further hastens the reaction.
Loss of ammonia is also incurred if the temperature is raised beyond 850° as
ammonia begins to dissociate at about that temperature.
If the Steam has carried off too much of the ammonium Sulphate as such, or if
too great an excess of Sodium Sulphate has been employed the resulting hydrogen
Sodium Sulphate contains too much of the neutral Sodium Sulphate and becomes
difficult of fusion, and thus its subsequent discharge from the apparatus by
flowing is hindered. Care should therefore be taken to have a proper mixture in
equivalent proportions with only a slight excess of Sodium Sulphate and to avoid
too rapid a current of Steam particularly before fusion has occurred.
If the Sodium Sulphate employed contains chloride of Sodium as is usually the
case, the mixture of Steam and ammonia gas resulting from the operation is
contaminated with vapours of ammonium chloride in addition to any vapours of
ammonium Sulphate which it may contain.
When the ammonia gas is passed through the condenser for the purpose of
condensing the Steam, these Salts, videlicet; Ammonium Chloride and ammonium
Sulphate are removed and flow out of the condenser dissolved in the condensed
water.
This Solution of ammonium Sulphate and Chloride, we mix again with Sulphate
of Soda and subject it anew to the above treatment, or if the Solution contains too
much chloride, we distil it with lime so as to obtain in the free state the ammonia
contained in the Solution.
We do not limit ourselves to any particular form of apparatus in which to
conduct the process according to our Invention, but those parts of the apparatus

page_text: which are in contact with the fused sodium hydrogen sulphate should not be of
wrought iron because wrought iron is rapidly acted upon and (in consequence
of contamination with iron. Sulphate) the hydrogen Sodium Sulphate becomes
difficult of fusion and cannot be discharged by simply causing it to flow out of the
apparatus. We therefore employ cast iron vessels provided with suitable apertures
for charging and discharging, which apertures must be provided with tightly
fitting lids or covers so that the apparatus may be closed air-tight during the
operation.
The apparatus is further provided with apertures for admitting the Steam and
for the escape of the Ammonia Gas and it is advantageous to provide for the.
agitation of the fused Salts.
We will describe with reference to the accompanying Drawing an apparatus
which can be advantageously employed in conducting the process according to our.
Invention.
Figure 1 of the said Drawing is a longitudinal section and Figure 2 a cross
section of the said apparatus. A represents a cast iron cylinder rotating on
trunnions mounted in bearings B and driven by means of suitable gearing shewn
at C in the Drawing as consisting of a driving pulley worm and worm wheel, the
whole supported by suitable frame-work. The cylinder A, is provided at one of its
ends with an opening. D, which can be closed by a door or cover so as to make the.
cylinder air-tight during the operation. When this opening D is in its highest
position the mixture of the Salts can be introduced through it into the Cylinder
and when it is in its lowest position the fused Salts can be discharged through it
by simply allowing them to flow out.
The trunnions on which the cylinder revolves are hollow.-Into one of them is
fitted air-tightly the pipe I, which reaches into the interior of the cylinder where
it is closed. Into. this pipe is placed a suitable pyrometer J, to allow the
temperature to be measured. Through the other trunnion passes air-tightly
through the stuffing box M a pipe L which carries off the gaseous ammonia and the
Steam to the condensing apparatus. The Steam is introduced by the pipe K which
passes through the pipe L and projects beyond it and is bent downwards in order
that the opening may not become clogged. The Steam may be conveyed directly
from a boiler, or it may with advantage be passed first through a superheater.
The pipe L is formed obliquely at its inner end as shewn, in order to prevent its
being clogged. For the purpose of agitating the Salts we may place a number of
breakers ribs or stirrers in the cylinder for example as shewn at N, or we may
effect the required agitation by passing the Steam through the mixture, which may
be effected by bending the Steam pipe K down and carrying it along the lower
part of the cylinder and perforating the said pipe so that the steam may issue in
numerous fine streams or currents.
The Cylinder A is enclosed in brickwork and at the ends by iron plates.
The fuel
G represents a furnace by which heat is applied to the said cylinder A.
gases after having passed round the Cylinder pass off by the chimney H where the
Draught can be regulated by a damper.
In the casing at the end nearest to the opening D there is a loose iron plate E
which can be removed in order that the opening D, may be uncovered or closed.
When the charge of Salts is to be introduced into the cylinder A, this iron plate E
and the door or cover of the opening D, are first removed, then the charge is
introduced by the funnel F, which is then removed. The door or cover of the
opening D, is closed and the plate E, replaced and the Cylinder A, is made to
revolve slowly whilst it is being heated. Steam is introduced by the pipe K, and
the ammonia passes off. through the pipe L. When the whole of the Ammonia is
driven off, the motion of the cylinder A, is arrested and the plate E, and the cover
of the opening D, are removed and the fused hydrogen Sodium Sulphate is allowed
to flow out of the said cylinder and is conducted by the shoot T into any suitable
receptacle.

page_text: Having now particularly described and ascertained the nature of our said
Invention and in what manner the same is to be performed we declare that what
we claim is:
The treatment of Sulphate of Ammonia with Sulphate of Soda in the presence
of Steam so as to produce free ammonia and enable the Sulphuric acid of the
Sulphate of ammonia to be utilized in the formation of hydrogen Sodium Sulphate
substantially as herein before described.