Improvements in or relating to the Production of Ammonia from Waste Nitrogenous Lyes or Gases.
Year: 1896

page_text: Date of Application, 31st Mar., 1896-Accepted, 15th Aug., 1896
[Communicated from abroad by LOTHAR STERNBERG, of Jersey, New Jersey,
United States of America, Chemist.]
Improvements in or relating to the Production of Ammonia from
Waste Nitrogenous Lyes or Gases.
I, HENRY HARRIS LAKE, of the Firm of Haseltine, Lake & Co., Patent
Agents, 45 Southampton Buildings, in the County of Middlesex, do hereby
declare the nature of this invention and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement :-
The process which forms the subject of the present invention is adapted for
successful use in transforming into ammonia the nitrogenous organic gases
generated by the dry distillation of animal refuse, such as hair, wool, bones, skin,
hides, blood and the like, also those resulting from the dry distillation of peat,
bog, and other bituminous matters, and especially to transform into ammonia the
nitrogenous organic compounds contained in the waste lyes resulting from the
extraction of sugar or the manufacture of alcohol from molasses.
The present invention embraces essentially the use of an aluminate, either an
aluminate of alkali or an aluminate of alkaline earths, as the principal ingredient
of a powdered mass of material employed as a carrier for the waste lye which is to
be treated for the manufacture of animonia; the aluminate being employed not
merely as a carrier, but also as a chemical re-agent.
Incidentally, the present invention embraces also a particular method of preparing
a carrier containing as its important ingredient aluminate of potassium which it is
preferred to employ.
In the present process the waste lye is subjected to heat in the presence of an
aluminate (preferably the aluminate of potassium) under such conditions that the
ammonia and other gases immediately generated are drawn or forced through a
body of incandescent material composed of a mixture of aluminate of potassium
and alumina whereby the nitrogenous gases thus generated are transformed into
animonia. At a later stage in the process the nitrogenous organic compounds
contained in the residuum of the lye are by further subjection to heat also
transformed into ammonia. The ammonia thus obtained is removed and fixed in
any usual manner, as, for example, by causing it to come in contact with sulphuric
acid in an ordinary condensing tower.
In the preparation of the carrier which I prefer to employ, I make use of
aluminiferous bauxite. If the bauxite contains silica in any large amount I add a
sufficient quantity of lime to counteract any effects of the silica which are obnoxious
to the formation of aluminate of potassium. I may use clay instead of bauxite, but
in such case I add a proportionately larger amount of lime. The bauxite having
been ground is mixed with powdered black-ash, or crude potash, in the proportion
of parts of bauxite to 1 of crude potasb. Sufficient water is added to the
mixture to make it plastic and it is then molded into blocks of any desired shape
and dried at a temperature of about 212° F. When the blocks are hard at this
temperature they are broken or crushed into pieces of convenient shape and the
crushed product is heated to redness in a furnace or retort of any known construction,
after which it is removed from the retort and ground to a powder. This powder,
consisting essentially of aluminate of potassium, aluminate of sodium and alumina,

page_text: together with the impurities originally present in the bauxite and in the black-ash
or crude potash, constitutes the material with which the waste lye, having been
previously concentrated to a density of 40° Baumé is first mixed in equal propor-
tions. To 100 parts of such concentrated lye and 100 parts of the described
powder I add 30 parts of bauxite. The proportions of the waste lye and the bauxite
are so regulated that the proportion of black-ash, resulting from the glowing, of
the waste lye, to the bauxite is the same as in the preliminary step of preparing
the aluminate of potassium, that is to say, 1 part of black-ash to 15 part of
bauxite. This proportion can of course be varied to some extent, but it is essential
to so regulate it that the mixed mass during and after the drying will neither
swell too much, or bake together, or crumble, or melt. Thus I have found that
if only part of bauxite is used with 1 part of black-ash, then the mixture is
liable to melt. I have also found that if bauxite is present in larger proportion
than 1 to 1 part of black-ash, then in the heating process the bricks are liable to
crumble.
It is likewise to be observed that while the proportion of waste lye introduced
into the carrier can be varied within certain limits, it is not desirable that there
should be less than 100 parts of the powder to 100 parts of the lye, because, on the
one hand, the drying of the mass would take too much time, and, on the other
hand, a sufficiently hard product could not be easily obtained if a greater
proportion of waste lye should be taken.
The mixing of the lye with its carrier may be effected in any of the well known
forms of mixers, preferably one which is provided with a heating apparatus in
order to evaporate part of the water, if the concentration of the lye is not high
enough. It will in any case be useful to add a small quantity of saw-dust to the
mixture in order to facilitate the drying operation.
The mixture, which at first is rather soft, is stirred until it becomes hard and
stiff and is then pressed into blocks of any desired shape. These blocks are then
dried at a temperature of about 212° F. When the blocks are found to be hard
at the temperature of 212° F. they are broken in pieces of convenient shape and
glowed (that is, heated to redness) in a retort and furnace of any known
construction. I preferably employ for this purpose the constructions similar t
those used for revivifying bone-black, which, having vertical retorts, facilitate
the conduct of the process continuously.
The gases which are produced during the glowing process, as well as any that
may be introduced from the outside are conducted in the same direction as the
glowing mass and are removed from the bottom of the retort. The final process
of glowing is conducted as follows:
The crushed bricks containing the waste lye are fed into the top of a retort
which is at first nearly filled with the mixture of aluminate of potash and alumina,
obtained from bauxite and black-ash, as hereinbefore described. The resulting
gases are conducted downward through the glowing body of material in the retort
and thereby the nitrogenous organic compounds, generated by the decomposition
of the lye in the upper part of the retort, are transformed into ammonia. As the
process goes on the incandescent mass will gradually be removed from the bottom
of the retort and the material afforded by the crushed bricks, which may be reganded
as the solid carrier of the waste lye, will continue to be fed into the top of the
retort. While the organic matters of the lye are transformed into gaseous
compounds, the solid carrier of the lye when it reaches the lower part of the
retort is perfectly calcined and has the same composition and will perform the
same function as the glowed mass of bauxite and black-ash originally introduced
into the retort.
The calcined mass from the retort may be ground and used together with
bauxite as a carrier for a new quantity of waste lye. The mass discharged from
the bottom of the retort, not used as a carrier for the lye, is a saleable product in
itself, or it may be leached with water and the resulting insoluble residue may be
used instead of bauxite for the purpose of being mixed with waste lye. Th

page_text: solution by being saturated with carbonic acid may be transformed into the alkaline
carbonates and insoluble hydrate of aluminium. The resulting hydrate of aluminium
is also a saleable product, but may be used instead of bauxite for mixture with
waste lye.
The solution of carbonates of potassium and sodium containing chloride and
sulphate of potassium (and possibly other salts) originally present in the waste
lye may be treated by the well known method of successive evaporation and
crystallization to obtain these different products from it.
The mechanical advantages of the carrier which I have described, and which
result from the inclusion in it of an aluminate and alumina are the following:
First, the bricks described when subjected to heat do not swell; secondly, they
do not crumble and thereby clog the retort; and, thirdly, they do not melt.
The chemical advantage of my carrier results from the presence in it of an
aluminate, the most effective one for my purposes being aluminate of potassium.
This chemically influences the formation of ammonia from the nitrogenous com-
pounds of the waste lye by a reaction similar to that of the hydrates of potassium,
sodium and lime. The reaction of the aluminates is at first not so energetic as
that of the alkalies, but it remains persistent while lime and the hydrates
of an alkali soon lose their effectiveness by being saturated with the
carbonic acid set free by the decomposition of the organic matters of the lye,
or perhaps introduced from the outside. Carbonic acid does not saturate an
aluminate.
In consequence of the persistent effectiveness of the aluminates I am enabled to
glow at a lower temperature than has heretofore been possible and to thus avoid the
danger of losing ammonia by dissociation when the high temperatures are
einployed. I am therefore able to conduct the process with the use of less
than the usual quantity of steam or non-oxidating gases. Moreover, in my
process a moderate quantity of oxygen may be admitted without perceptible
loss of ammonia.
Of course my process of transforming into ammonia the nitrogenous gases
generated by the dry distillation of the waste lye, by conducting these gases
through an incandescent mass containing essentially an aluminate of either
potassium or sodium, or aluminates of both potassium and sodium, can be used to
transform into ammonia any kinds of nitrogenous organic gases of any origin
whatever, as, for instance, those resulting from the dry distillation of animal refuse,
such as hair, wool, bones, skin, hides, blood, and the like, or of mineral inatters,
such as peat, bog, and other bituminous substances. By conducting these gases
through a heated retort filled with pieces of convenient shape of the material
obtained, as described above, from bauxite and black-ash, or crude soda or potash,
the said gases are transformed into ammonia.
While I prefer to employ bauxite for the preparation of the aluminate, it is to
be understood that any kind of alumina, oxide of aluminium, hydrate of aluminium,
clay, or such salts of aluminium as will give aluminates if glowed with alkaline
salts can be used for that purpose.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, as communicated to me by
my foreign correspondent, I declare that what I claim is :-
1. The herein described process of obtaining ammonia from the waste lyes
resulting from the extraction of sugar, or the manufacture of alcohol from
molasses, which consists in subjecting such waste lyes to the heat of incandescence
in the presence of an aluminate, preferably the aluminate of potassium, as herein
set forth.
2. The herein described method of treating the waste lyes remaining after the
extraction of sugar or the manufacture of alcohol from molasses, preparatory to
extracting ammonia therefrom which consists in concentrating such lyes to a
deusity of, say, 40° Baumé, then mixing such coucentrated lyes with alumina

page_text: and an aluminate in such proportions as will form a plastic mass, then forming
such plastic mass into bricks of convenient size and drying the same
set forth.
3. The herein described process of obtaining ammonia from waste lyes
resulting from the extraction of sugar or the distilling of alcohol from molasses,
which consists in first mixing the waste lye, after convenient concentration, with
an aluminate, preferably the aluminate of potassium and with alumina, forming
the resultant mixture into bricks and drying the same, then heating them to
redness, and thereby forming an incandescent contact body and in conducting over
said incandescent contact body the nitrogenous organic vapours generated by the
act of heating said contact body and thereby transforming said vapours into
ammonia.
4. The herein described process of transforming gaseous nitrogenous organic
compounds into ammonia, which consists in conducting such gases over a glowing
contact-body, composed essentially of an aluminate, as, for example, the aluminate
of potassium.
Dated this 21st day of March 1896
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.