IMPROVEMENTS IN THE TREATMENT OF AMMONIACAL LIQUORS OF GAS WORKS IN ORDER TO OBTAIN VALUABLE PRODUCTS THEREFROM
Year: 1872

page_text: LETTERS PATENT to Thomas Christy, the younger, and Alexander
Bobrownicki, both of No. 155, Fenchurch Street, in the City of
London, for the Invention of "IMPROVEMENTS IN THE TREATMENT OF
AMMONIACAL LIQUORS OF GAS WORKS IN ORDER TO OBTAIN VALUABLE
PRODUCTS THEREFROM."
Sealed the 9th July 1872, and dated the 16th May 1872.
PROVISIONAL SPECIFICATION left by the said Thomas Christy and
Alexander Bobrownicki at the Office of the Commissioners of
Patents, with their Petition, on the 16th May 1872.
1
We, THOMAS CHRISTY, the younger, and Alexander Bobrownicki, both
of No. 155, Fenchurch Street, in the City of London, do hereby declare
the nature of the said Invention for "IMPROVEMENTS IN THE TREATMENT OF
AMMONIACAL LIQUORS OF GAB WORKS IN ORDER TO OBTAIN VALUABLE PRODUCTS
THEREFROM:"-
The ammoniacal liquors from gas works are at present generally only
worked commercially for the purpose of extracting therefrom ammonia,
either volatile or in combination with other matters.

page_text: In carrying out our improvements we utilize not only the ammonia,
but other of the substances contained in such ammoniacal liquor. These
substances we arrange in groups corresponding with their chemical
radicals, thus :—
1. Azoted substances whose radical is azote combined with hydrogen 5
(ammonium Az H³).
2. Azoted substances whose radical is azote combined with carbon
(cyanogen Az O²)..
3. The various substances present in ammoniacal waters or in the
product obtained in working according to the Invention described in the 1
application, No. 1327, filed the 2nd May 1872.
I. We extract the ammonia either during the formation of the dry or
stable product referred to in such application, or at the moment of
silicating the ammoniacal liquids, or during the treatment of such
product, in short, at any convenient time by means of fixed alkalis
(potash, soda, or lime), an operation which is analagous to and for a
like purpose to the treatment of the liquid ammoniacal waters.
For the purpose of utilizing the ammonia we effect the alkaline
admixture in a closed vessel, avoiding the high temperature usually
adopted (to extract the ammonia) from ammoniacal water, and we
employ an air pump (which may be slightly warmed if found desirable)
to facilitate the driving out of the ammonia.
II. We divide the working of the cyanogen substance into two
distinct parts, a and b.
(a.) The first consists in allowing the atmospheric air to operate on the
cyanated substances found in the ammoniacal liquors for various periods.
(b.) The second part consists of the extraction of the prussiates or the
sulfocyanates which may be obtained in different ways, according to the
kind of product of cyanogen desired to be obtained, but we will give the
following as an example:-
The cyanogen substances present in the ammoniacal waters are
recognized as sufficiently aerated when the alkaline liquor (after the
extraction of the ammonia) can form blue precipitate in the iron

page_text: solution, or when the liquor is treated by an acid gives the same blue
precipitate with salt of iron or with the peroxide of iron.
We treat ammoniacal waters recently obtained with the alkali silicate
of soda or of potash. We collect the ammonia as it has been stated in
No. 1. We precipitate the silica by an acid to form a gelatinous mass,
such as referred to in the Specification above referred to. We treat the
product when it has been sufficiently exposed to the air by an alkaline
solution (potash or soda) until the mass has become exhausted. We
put the drainings in a solution of acidulated salts of iron. The operation
is well done when all the mass is a little acid and presents a fine violet
blue color. We leave the formation precipitated to settle. We decant
the liquor, leaving the solid part, which we wash in cold water in the
ordinary way of purifying Prussian blue.
If the drainings contain silica before the pouring in of the salts of
iron it will be purified by the addition of a small quanity of lime, which
will precipitate the silica and form silicate of lime, and thus we obtain
deep blue of a fine colour.
The ammoniacal water, which having remained a sufficient time in
the cistern, is treated directly, either by the alkalis or by the acids,
producing a fine blue or blue character of color. These waters would
have been silicated as we have said above; in this case we separate the
liquid part from the gelatinous mass, we then pour into the solution
some salts of iron in order to form the blue precipitate. The solid
residue after the separation of the liquid is thrown in a heap and exposed
to the free action of the atmosphere. It can be treated after a certain
time as before described, or it can be sold directly as a raw product.
The blue which we obtain by the precipitation can be transformed
easily if wished by the ordinary means into prussiate of potash, or ferro-
cyanic acids, or other commercial products.
III. The extrication of the various matters under the form of sub-
products formed during the principal operations can be made in the
ordinary manner after having withdrawn all the azoted matter.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Thomas Christy and Alexander Bobrownicki in
the Great Seal Patent Office on the 16th November 1872.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, THOMAS
CHRISTY, the younger, and ALEXANDER BOBROWNICKI, both of 155,
Fenchurch Street, in the City of London, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Sixteenth day of May, in the year of
our Lord One thousand eight hundred and seventy-two, in the thirty-
fifth year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto us, the said Thomas Christy and Alexander Bobrownicki,
Her special license that we, the said Thomas Christy and Alexander
Bobrownicki, our executors, administrators, and assigns, or such others
as we, the said Thomas Christy and Alexander Bobrownicki, our
executors, administrators, and assigns, should at any time agree with,
and no others, from time to time and at all times thereafter during
the term therein expressed, should and lawfully might make, use,
exercise, and vend, within the United Kingdom of Great Britain and
Ireland, the Channel Islands, and Isle of Man, an Invention for "Im-
PROVEMENTS IN THE TREATMENT OF AMMONIACAL LIQUORS OF GAS WORKS IN ORDER
TO OBTAIN VALUABLE PRODUCTS THEREFROM," upon the condition (amongst
others) that we, the said Thomas Christy and Alexander Bobrownicki,
our executors or administrators, by an instrument in writing under our,
or their, or one of their hands and seals, or under the hand and seal
of one of us or them, should particularly describe and ascertain the
nature of the said Invention, and in what manner the same was to
be performed, and cause the same to be filed in the Great Seal Patent
Office within six calendar months next and immediately after the date of
the said Letters Patent.
NOW KNOW YE, that we, the said Thomas Christy and Alexander
Bobrownicki, do hereby declare the nature of the said Invention, and in
what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement thereof, that is to
say:-

page_text: worked commercially for the purpose of extracting therefrom ammonia,
either volatile or in combination with other matters.
In carrying out our improvements, we utilize not only the ammonia
but other of the substances contained in such ammoniacal liquor. These
substances we arrange in groups, corresponding with their chemical
radicals, thus:-
1. Azoted substances, whose radical is azote combined with hydrogen
(ammonium Az H 3).
2. Azoted substances whose radical is azote combined with carbon
(cyanogen Az C 2).
3. The various substances present in ammoniacal waters or in the
product obtained in working according to the Invention described in the
Specification of Letters Patent granted to me, the said Thomas Christy,
and bearing date the 2nd day of May, of the present year, No. 1327.
In order that our Invention may be more fully understood, we will
proceed to describe the operations as pursued by us. In doing so we
will give three examples of operations, which may serve as a practical
guide for almost every case.
(1.) At present ammoniacal liquors of gas works are operated upon
to extract the ammonia from them by distillation, and the apparatus
ordinarily employed for the purpose is that known as Coffey's, Mallett's,
and others, with a view to obtain for commercial purposes either the
alkaline ammonia or other ammoniacal salts in a state of sufficient purity.
(2.) Such waters are also operated upon to obtain therefrom artificial
manures, or they are used direct as manure; or
(3.) In the case of small gas works far from other manufacturing
operations, the waters are most frequently thrown away and not utilized.
This occurs especially in hot countries where it is difficult to keep the
waters and to transport them in liquid condition.
In operating according to our Invention in the first of such cases we
proceed as follows:-During the distillation of the ammoniacal waters
in column apparatus (Coffey's), heated by steam, the quantity of air is
most frequently sufficient, consequently the introduction of air is only

page_text: necessary in apparatus heated by direct fire heat. During the distillation
of ammonia, the greater portion of the cyanogen substances pass with it,
either in a state of combination or free, consequently we operate first on
the volatile portion which escapes from the cistern during the saturation
of the ammonia by some acid. As most frequently these portions are
condensed before being burnt we can operate on the condensed liquid,
but it is more rational before the condensation to pass all these vapours
through a ferro alkaline reactive, concentrated as much as possible in
order to fix the cyanogen substances. This process is successful and
the reaction occurs very quickly. When the reactive becomes too dilute,
a portion of the cyanures may be lost, but in no case is the alkali used
lost.
To prepare the reactive alkaline oxides carbonates or silicates may be
used, which are easily decomposed. The same rule applies to the salts
of iron. We have used with success on account of its cheapness common
caustic, soda, and sulphate of iron, mixing them in equivalent pro-
portions, such as is indicated by the composition of ferrocyanide of
sodium. An excess of iron is frequently very useful in the presence of
sulphuretted hydrogen, which is found in the ammoniacal waters in very
considerable quantities. We have made use of the same cisterns for the
reactive as those used for saturating the ammonia, but a saturator
similar to the saturator used for purifying coal gas might be used, or
other suitable apparatus, according to the local condition, might be
used with success, provided it offers a large surface to the contact of
the gas with the reactive, and if ammonia is observed coming from
the purifier it should be fixed. The alkaline ferrocyanide is formed
progressively as the alkaline state of the reactive diminishes.
The operation should be continued until only a small quantity of free
alkali is left, but care must be taken in order to prevent the loss of
cyanides which might be precipitated with the sulphuret of iron when
the saturation is too much advanced. The reactive may be allowed to
remain several days in the saturator without losing its strength.
The progress of saturation is easily observed by taking a sample of the
liquor from the overflow placed at the height corresponding with the
pressure of the acid cistern, and by examining the sample with sulphuric
acid to establish the quantity of free alkali. When the saturation is

page_text: concluded and the mass sufficiently cooled, it should be transferred to
an open cistern where it should remain until the complete precipitation
of a black deposit, which will be found principally composed of sulphuret
of iron. The liquor must be separated from the deposit in a slightly
6 alkaline state, and then it may be kept a considerable time, gaining in
value for dyeing purposes. This liquor may be sold at once to the dyer
as a coloring matter for fine voilet blue when treated by an acid
(muriatic or tartaric is preferable), and without a mordant or with a
mordant to vary the shade. It will in many cases replace indigo.
The liquor may be crystallized by ordinary means used in the manu-
facture of alkaline ferrocyanides. It can also be used for the manufacture
of the coloring matter in a dry state for painters and dyers.
The liquor may be separated from the deposit by compression after
decantation and filtration, or else the deposit may be well washed with
the water from the ammoniacal distilling apparatus. A less concentrated
liquor is thus obtained, but it is easy to extract the blue coloring matter
from it by mixing the liquor with a dissolution of an acidulated ferric
salt by well washing the blue deposit and drying it in the ordinary
manner. The coloring matter may be precipitated by means of salts of
tin (chloride) useful for dyeing.
The liquor separated from the blue deposit forms a sub-product, which
may be treated with sulphuric acid to regenerate the caustic soda, which
when concentrated may be reused for subsequent operations.
The sub-product may be concentrated by crystallization or sold direct
to the dyers as a mordant or as a brown coloring matter, for which
purpose it is sufficient to wash the stuff dyed in alkaline water.
In the second class of cases referred to, we operate in the following
manner: The ammoniacal waters for agricultural use should be freed
from cyanogen matters, as these substances are found injurious to
vegetation. We render the waters fit for agriculture by the following
method: We liberate the cyanogen substances by precipitating the
ammonia by means of superphosphate of lime, by phosphoric acid, or
some other phosphate mono or bibasic. The deposit obtained, separated
from the slightly acid liquor, forms a manure composed of fertilizing
3 matters which may be advantageously used as a substitute for the best

page_text: guano. This manure will produce a quick or slow effect, depending on
its degree of solubility being increased by the addition of an acid, as
with other kinds of phosphates. The slightly acid liquor separated from
the deposit and from the matter floating on the surface is useful for
dyeing purposes, or it may be used for extracting the coloring matter
from it by means of a ferric accidulated salt by proceeding as already
mentioned. Further, this liquor saturated with some alkali may be
purified and concentrated by crystallization as practised in the ordinary
manufacture of alkaline ferrocyanides.
The mixture with the phosphates is effected at the ordinary tempe-
rature in proportion to the formation of the precipitate. It is well to
make the mixture in closed vessels to prevent the disagreeable emanations
containing sulphuretted hydrogen, which may be utilized or burnt in
the ordinary manner. This operation being conducted without any
distilling apparatus can be followed with great facility and economy.
In the third class of cases we operate in the following manner: - _We
proceed as described in the aforesaid Specification of Letters Patent
granted to me, the said Thomas Christy, dated the 2nd day of May in
this present year, No. 1327, to obtain a concentrated product (silicoid).
If this product (silicoid) has been made from the ammoniacal liquor of
gasworks by precipitating the silica by sulphuric acid, the treatment of
this product is easy, as it is simply necessary to mix it with caustic lime
in sufficient proportion to precipitate the sulphuric and silicic acids. By
this means the substances will be separated, the ammoniacal parts being
freed are easily driven off in a gaseous state, the soda becoming caustic
reacts on the cyanogenized substances, fixing them in the liquor in the
form of alkaline ferrocyanides if iron should be present in sufficient
quantity in the product. For this reason it is always well to test the
product before hand, and to supply the iron wanting at the commencement
of the operation. Further, the solid portion composed of silicate and a
sulphate of lime may be used for making cements, also certain manures
when it is not otherwise valuable.
The liquor after the extraction of the ammonia and thoroughly
separated from the deposit forms the liquor with which we proceed as

page_text: The mixture and operation with lime is made in an ordinary lime box
or mixer, in which the liquid ammoniacal waters are decomposed by
treating them with lime to free the ammonia.
Having thus described our Invention and means which we adopt in
carrying the same into effect, we would have it understood that what we
claim is, the treatment of ammoniacal liquors of gasworks in order to
obtain not only ammonia therefrom, but also other valuable products,
substantially as described.
In witness whereof, we, the said Thomas Christy and Alexander
Bobrownicki, have hereunto set our hands and seals, this Fifteenth
day of November, in the year of our Lord One thousand eight
hundred and seventy-two.