AN IMPROVED METHOD of TREATING AMMONIUM CHLORIDE
Year: 1884

page_text: We, WILLIAM PERCY COCHRANE of 3 Belmont Terrace, Coatham, Redcar in the
County of Yorkshire, Student in Chemistry and WILLIAM BRAMLEY, of 18 Clarence
Street, Middlesbro-on-Tees, in the County of Yorkshire, Professional Chemist, do
hereby declare the nature of our said invention for AN IMPROVED METHOD of
TREATING AMMONIUM CHLORIDE" to be as follows:―.
"
In the manufacture of Carbonate of Soda by what is known as the Ammonia
process, the resulting Ammonium Chloride is treated with Lime and the Calcium
Chloride thus produced is allowed to go to waste, thus losing the Chlorine.
The object of our invention is to treat the Ammonium Chloride with Magnesia
in such proportions and in such a manner as to completely disengage the Amimonia
and to effect the reaction represented by the equation:
2 NH, Cl + 2 Mg O
=
Mg, Cl, O2 NH, + H, O.
We carry out our invention in the following manner :
In the present method of Soda manufacture known as the Ammonia process,
Salt is treated with Ammonium Carbonate in such a manner as to form Sodium
Carbonate and Ammonium Chloride. The Ammonium Chloride so obtained is in
the form of a solution, but if not in this form, water must be added to make a
solution.
To this solution of Ammonium Chloride we add Magnesia in such quantities as
will satisfy the equation given above, making the addition gradually, or all at
once, whichever method is adopted we do not find that there is any practical
difference in the result, but we prefer to add all at once. On the application of
beat the Ammonia commences to disengage, and continues as the solution evaporates.
The solution must be stirred from time to time, to prevent the precipitate or other
suspended matter from becoming hard or dry on the bottom or sides of the vessel
in which the operation is conducted. We find that the Ammonia is most
satisfactorily given off when the solution is of about the consistency of milk of
lime, and we recommend that this consistency be maintained (by the addition of
water from time to time if necessary) until the Ammonia be wholly given off. The
last of the Ammonia can of course be obtained by evaporating to dryness, but in
this case there is the risk of raising the temperature to too high a point and thus
disengaging a portion of the Chlorine. The temperature at which this process is
most satisfactorily performed is, in our opinion, just below the boiling point of the
solution.

page_text: In the Ammonia process the solution of Ammonium Chloride obtained contains
a large percentage of salt-This salt we prefer to extract from the solution by
what is technically termed "fishing" but if it be left in the liquor it does not
interfere with our process otherwise than to require a slightly longer time for its
performance.
We find that it is advantageous to employ an excess of Magnesia over and above
the theoretical quantity represented by the equation given. The excess which we
find gives the best result is one of about 12 to 15 per. cent. The result of adding
such an excess is that it accelerates the operation considerably and thus effects a
saving in fuel or such source of heat as may be employed for obtaining the requisite
temperature, and also guards against any failure in effecting the complete
decomposition of the Ammonium Chloride owing to the presence of impurities
in the Magnesia.
The Magnesia used should be the purest available though that obtained in a
native condition may be used, after proper preparation, so as to eliminate any such
foreign substance as would interfere with the reaction.
The Ammonia being disengaged, there remains in the solution a mixture of
Magnesia and Magnesium Oxychloride. This can be evaporated to dryness and
heated in contact with air under certain conditions, as proposed by Mr Weldon, in
his address to the Chemical Society on July 9th 1884, so as to obtain Chlorine
and Hydrochloric Acid.
Although we have described our invention as more particularly applied to
Ammonium Chloride resulting from the treatment of salt in the Ammonia process,
yet it is equally applicable to Ammonium Chlorido resulting from other processes.
Dated this 13th day of August 1884.
ABEL & IMRAY,
Agents for the Applicants,
28, Southampton Buildings,
London, W.C.

page_text: COMPLETE SPECIFICATION.
WO WILLIAM PERCY COCHRANE of 3 Belmont Terrace, Coatham, Redcar in the
County of Yorkshire, Student in Chemistry and WILLIAM BRAMLEY, of 18 Clarence
Street, Middlesbro-on-Tees in the County of Yorkshire, Professional Chemist, do
hereby declare the nature of our said invention for "AN IMPROVED METHOD OF
TREATING AMMONIUM CHLORIDE" and in what manner the same is to be performed,
to be particularly described and ascertained in and by the following statement :—
In the manufacture of Bi-Carbonate or Carbonato of Soda by what is known as
the Ammonia process, the resulting Ammonium Chloride is treated with Lime, and
the Calcium Chloride thus produced is in most cases allowed to go to waste, thus
losing the Chlorine.
The object of our invention is to perform the operation of regenerating the
Ammonia from the residual liquors of the Ammonia process by means of Magnesia
in such a way as to obtain a residual product of Magnesium Oxychloride, which,
by methods forming no part of this invention, can be decomposed into Magnesia
and Hydrochloric Acid or Magnesia, Chlorine and Hydrochloric Acid.
We carry out our invention in the following manner :-
In the process of Soda manufacture by the Ammonia process, Salt is treated
with Ammonium Bi-Carbonate in such a manner as to form Sodium Bi-Carbonate
and Ammonium Chloride. (There also remains in the residual liquor a certain
proportion of Sodium Chloride) The object of our process is to treat this residual
liquor with Magnesia in such a way as to obtain, after the evolution of the
Ammonia, a residual product of Magnesium Oxychloride.
The Sodium Chloride in the liquor should be extracted wholly or in part by what
is technically termed "fishing" (which will be well understood) before the addition
of the Magnesia; though this is not necessary to our process, as we find that its
presence only interferes to the extent of causing a slightly longer time to be
required to effect the decomposition of the Ammonium Chloride.
As it may,
however, interfere with the subsequent process of the decomposition of the
Oxychloride, (which process forms no part of this invention) we prefer to separate
it at this stage.
To the liquor thus obtained we add Magnesia in the proportion of two molecules
of magnesia, i.e. 80 parts by weight of Mg O., or its equivalent weight of Magnesium
Hydrate, to two molecules of Ammonium Chloride, i.e. 107 parts by weight of
NH, Cl. (subject to what is hereinafter stated).
The Ammonia is readily disengaged on the application of heat, and the residual
liquor on being evaporated down will be found to contain an oxychloride of
Magnesium, which, if allowed to set, becomes a hard solid mass.
The liquor should be stirred or mechanically agitated during the process.
We find that the Ammonia is most satisfactorily disengaged when the liquor is
of about the consistency of milk of lime, and we recommend that this degree of
concentration be maintained until the Ammonia be disengaged either completely
or to such an extent as may be requisite.
It is advantageous to employ an excess of Magnesia over and above the
theoretical quantities afore mentioned. The use of adding such an excess is that

page_text: it accelerates the operation considerably, and thus effects a saving in fuel or such
source of heat as may be employed for obtaining the requisito temperature, and
also guards against any failure in effecting the completo decomposition of the
Ammonium Chloride owing to the presence of impurities in the Magnesia.
The Magnesia used should be the purest available, though that obtained in a
native condition may be utilised after proper preparation so as to eliminate any
such foreign substanco as would interfere with the reaction previously mentioned.
The Ammonia being disengaged, the liquor should be evaporated down and the
resulting Oxychloride of Magnesium treated for its decomposition according to
methods which do not form part of this invention.
Although we have described our invention as more particularly applied to the
Ammonium Chloride liquors of the Ammonia process of Soda Manufacture, yet it
is equally applicable to Ammonium Chloride resulting from any other process.
We are aware that methods have been proposed for decomposing the Ammonium
Chloride of the aforesaid residual liquors by means of Magnesia, but all processes
have hitherto produced as a residue Magnesium Chloride, and owing to various
difficulties arising they have not proved commercially successful. By our process
we obtain a residual product of Magnesium Oxychloride, a compound which is
totally distinct from Magnesium Chloride in composition and physical properties,
and from which by a process which does not form any part of the present invention,
Chlorine in a free state and Hydrochloric Acid can be obtained with facility and
the Magnesia regenerated for further use. By our process also the Ammonium
Chloride is very much more rapidly decomposed than by the previously mentioned
processes, thus effecting a saving in cost.
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 method substantially as herein described of treating Ammonium Chloride
by Magnesia in such a way as to obtain a residual product, after the Ammonia has
been disengaged, of Magnesium Oxychloride.