IMPROVEMENTS IN THE RECOVERY OF CARBONATE OF AMMONIA FROM SEWAGE
Year: 1874

page_text: LETTERS PATENT to Henry Young Darracott Scott, of Ealing, in the
County of Middlesex, Major-General, C.B., for the Invention of
"IMPROVEMENTS IN THE RECOVERY OF CARBONATE OF AMMONIA FROM
SEWAGE."
Sealed the 18th September 1874, and dated the 13th July 1874.
PROVISIONAL SPECIFICATION left by the said Henry Young Darracott
Scott at the Office of the Commissioners of Patents, with his
Petition, on the 13th July 1874.
I, HENRY YOUNG DARRACOTT SCOTT, of Ealing, in the County of
Middlesex, Major-General, C.B., do hereby declare the nature of the
said Invention for "IMPROVEMENTS IN THE RECOVERY OF CARBONATE OF AMMONIA
FROM SEWAGE," to be as follows:-
:-
This Invention has reference to the extraction of carbonate of ammonia
from sewage, such as decomposed urine, gas liquor, and other polluted
waters containing this substance.
In carrying out my Invention I commence operations, as a ready
means of arriving at the compound I require, by employing calcined

page_text: magnesite or magnesia produced in any other way, to which has been
added such a quantity only of phosphoric acid, or soluble phosphate, or
phosphate dissolved in mineral acids as will leave the magnesia in con-
siderable excess.
I agitate the liquid containing the carbonate of
ammonia with this compound, or I filter the liquid through it. By this
means the carbonate of ammonia in the liquid adheres to or combines
with the magnesic compound. After saturation with carbonate of
ammonia the compound is removed from the liquid, and is exposed to
heat in a distilling apparatus with a condensing vessel attached to it.
The carbonate of ammonia on expulsion crystallizes in the condenser or
distils over in solution, and may be removed at intervals. The caustic
ammonia which may be driven off from the compound may be fixed by a
mineral acid.
When the expulsion of the ammoniacal compound has been carried
far enough, the resulting magnesic salts are employed for extracting the
ammonia from a fresh volume of the liquid. The free magnesia which
was originally present has now been converted into a precipitated
carbonate, and the compound is more efficacious than at first. By
passing the distillate through lime or other alkali or alkaline earth the
whole of the ammonia may be obtained in the caustic form, or by
distilling it into sulphuric acid, or muriatic acid, or phosphoric acid, the
ammonia may be recovered as a sulphate, or chloride, or phosphate, all
which substances have manufacturing or other useful applications.
Such acids may also be added to the magnesic compound on removal
from the liquid to fix the ammonia compounds and to form manures.
Phosphoric acid can be added for this purpose with great advantage.
.
I obtain the phosphoric acid necessary either from coprolite, phosphate
of alumina, or any other cheap source of phosphoric acid, employing
well-known methods for the purpose.
The foregoing process may be used in conjunction with the dibasic.
phosphate of magnesia, which can be usefully employed for the extraction
of the last portions of ammonia from sewage, and after its employment
the liquid is in many cases with advantage treated with lime.

page_text: filed by the said Henry Young Darracott Scott in the Great Seal
Patent Office on the 13th January 1875.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, HENRY
YOUNG DARRACOTT SCOTT, of Ealing, in the County of Middlesex, Major-
General, C.B., send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Thirteenth day of July, in the year of our Lord
One thousand eight hundred and seventy-four, in the thirty-eighth year
of Her reign, did, for Herself, Her heirs and successors, give and grant
unto me, the said Henry Young Darracott Scott, Her special licence
that I, the said Henry Young Darracott Scott, my executors, admini-
strators, and assigns, or such others as I, the said Henry Young
Darracott Scott, my 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 "IMPROVEMENTS IN THE RECOVERY OF CARBONATE OF AMMONIA PROM SEWAGE,"
upon the condition (amongst others) that I, the said Henry Young
Darracott Scott, my executors or administrators, by an instrument in
writing under my, or their, or one of their hands and seals, 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 Scal Patent Office within six calendar months next
and immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said Henry Young Darracott Scott, do
hereby declare the nature of my said Invention, and in what manner
the same is to be performed, to be particularly described and ascertained
in and by the following statement (that is to say) :—
This Invention has reference to the extraction of carbonate of ammonia
from sewage, such as decomposed urine, gas liquor, and other polluted
liquids containing this substance in sufficient quantity. It is not adapted
for the treatment of dilute solutions of carbonate of ammonia.

page_text: In carrying out my Invention I modify the process somewhat,
according to the nature of the product aimed at. If I propose making
à manure I commence operations (as a ready means of arriving at the
compound I require) by employing calcined magnesite or magnesia
produced in any other way, to which has been added such a quantity
only of phosphoric acid as will leave the magnesia in considerable excess.
I sometimes also add directly to the magnesia a quantity of phosphate
of magnesia, previously prepared to produce similar results, or in lieu of
magnesia I may employ calcined dolomite. I agitate the liquid con-
taining the carbonate of ammonia with this compound, or I filter the
liquid through it. By this means the carbonate of ammonia in the
liquid adheres to or combines with the magnesic compound, unless the
magnesia added is sufficient to decompose the whole or a large part of
the carbonate of ammonia in the liquid, the phenomenon being preceded,
accompanied, or followed by the following changes :-(a) some portions
of the carbonate of ammonia are decomposed by the magnesia, carbonate
of magnesia being formed and ammonia set free; (b) other portions of
the carbonate of ammonia unite with the carbonate of magnesia thus
formed; (c) the ammonia set free by the decomposition of the carbonate
is taken up by the phosphate of magnesia. The material thus charged
with ammoniacal compounds on removal from the liquid is treated with
sulphuric acid in sufficient quantity to fix the ammonia compounds and
to form manures. Phosphoric acid can also be added for this purpose
with great advantage..
I obtain the phosphoric acid necessary from phosphorite, coprolites, or
phosphate of iron, or from any other cheap source of phosphoric acid,
employing well-known methods for the purpose.
Instead of employing phosphate of magnesia mingled with the
carbonate of magnesia, the phosphate may be applied at a subsequent
stage of the process of dealing with ammoniacal liquids, and it may
without departing from the nature of this Invention be omitted altogether.
It exercises however two important ammoniacal functions, though not
an essential element of my process; it absorbs the ammonia set free
when the magnesia becomes carbonated by decomposition of carbonate
of ammonia, and if subsequently applied it recovers not only any free
ammonia left in the liquid, but also the ammonia of such portions of
carbonate of ammonia as could not (owing to the necessity of the presence
of carbonate of ammonia in solution, in order to preserve the stability of

page_text: the ammoniacal magnesic carbonate) be removed by carbonate of magnesia
only.
The proportions of the phosphoric acid and the magnesia may be varied
considerably, but it is better that they should bear reference to the
strength of the ammoniacal liquid with which these materials are
employed. In proportion as this is stronger in carbonate of ammonia
the proportion of the magnesia may be greater; also if carbonate of
magnesia is used, and consequently less free ammonia is formed, the
phosphoric acid may be proportionately reduced.
In some cases, in which increase of phosphoric acid in proportion to
the ammonia present in the manure is aimed at, I employ soluble
phosphate of lime in lieu of phosphoric acid; or in lieu of adding the
phosphoric acid or soluble phosphate direct to the magnesia I first
treat the ammoniacal liquid with magnesia, then neutralize the free
ammonia which results from this process with phosphoric acid or soluble
phosphate, and in a third operation stir this liquid with or filter it
through magnesia. The magnesia compound of the third operation may
finally be used in the first stage of the process to treat a fresh quantity
of ammoniacal liquid.
The sulphate of lime resulting from the manufacture of soluble
phosphate by the aid of sulphuric acid may be mixed with the
ammoniacal magnesia compound which results from these operations, in
order to fix the ammonia through the double decomposition which takes
place between the carbonate of ammonia and sulphate of lime.
The foregoing observations will make it clear why in the preparation.
of manures I prefer to make use of phosphate of magnesia in conjunction
with the magnesia in the preparation of manures, but if the primary
object is the recovery of carbonate of ammonia, and the manufacture of
manure is an incidental process adopted with the view of economizing
ammonia I proceed in the following manner. I wish it however to be
understood that the before-mentioned method of arriving at the com-
pound I require for the recovery of carbonate of ammonia (viz., taking
advantage of the carbonic acid present in the liquid treated in com-
bination with ammonia) is not the only method by which it could be
produced. I can, for example, effect the same object by passing carbonic.
acid through the magnesia in a state of suspension in water; or again,
I may even employ a cheap salt of magnesia, like chloride of magnesium,

page_text: to form the carbonate of magnesia required. By adding this salt to the
ammoniacal liquid in regulated proportion, according to the amount of
carbonate of ammonia present, the double decomposition ensues between
the carbonate of ammonia and chloride of magnesium, but such a plan
of obtaining carbonate of magnesia is seldom economical.
In carrying out the process I arrange several vessels, which we will
call Nos. 1, 2, 3, 4, arranged in series. Into vessels 1, 2, 3, 4, I introduce
a quantity of sewage, and add thereto magnesia in quantity proportioned
to the size of the vessels and the ammoniacal strength of the liquid to
be dealt with. In average cases I employ about one-quarter pound of
magnesia to four gallons of the sewage. By means of machinery or other-
wise I agitate together the liquid and magnesia at intervals for a day or
two, and then allow the magnesic compounds to settle. After the
settlement I draw off the supernatant liquid into vessel No. 2, and fill
up No. 1 with a fresh portion of liquid. The contents of No. 2 arc
similarly treated, and the supernatant liquid passed on to No. 3, and
so on.
When No. 1 has been filled with liquid three or four times the
magnesia will be found to be converted to a great extent into an
ammoniacal magnesic carbonate, in which the ammonia is so lightly
held that it can be removed by a gentle heat, and is entirely expelled at
a red heat. After therefore the carbonate of magnesia formed has
combined with as much carbonate of ammonia as it will readily absorb,
the compound is removed from the liquid, and is exposed to heat in a
distilling apparatus with a condensing vessel attached to it. The
carbonate of ammonia on expulsion crystallizes in the condenser or distils.
over in solution, and may be removed at intervals.
When the expulsion of the carbonate of ammonia has been carried far
enough, the resulting magnesic carbonate is employed for extracting the
ammonia from a fresh volume of the liquid. In this case the magnesia
being already in the condition of carbonate the work of breaking up the
carbonate of ammonia is avoided.
The liquid resulting from the treatment by carbonate of magnesia.
may be subjected to further processes for the recovery of the ammonia
still left in it. The foregoing process, for instance, may be used in
conjunction with the dibasic phosphate of magnesia (as already indicated),
which can be usefully employed for the extraction of the last portions

page_text: of ammonia from decomposed urine, gas liquor, and other like liquids,
and after its employment the liquid is in many cases with advantage
treated with lime and (for the purposes of purification) with charcoal.
The liquid resulting from the treatment with carbonate of magnesia
may also be subjected to distillation for the recovery of further portions of
the ammonia.
In lieu of agitating the carbonate of magnesia with the liquid dealt
with, I may .as already indicated so arrange that the liquid shall
gradually filter through layers of this substance, and I may use the
salt also for filtering the urine from street urinals or from drains made
to carry the urine, slops, and the drainage from privies into the sewers.
Having now set forth the nature of my Invention of " Improvements
in the Recovery of Carbonate of Ammonia from Sewage," and explained
the manner of carrying the same into effect, I wish it to be understood
that under the above in part recited Letters Patent I claim, treating
sewage, such as decomposed urine, gas liquor, and other polluted liquids
containing carbonate of ammonia with carbonate of magnesia (whether
in conjunction or not with phosphate of magnesia) or with magnesia
(which will combine with the carbonic acid of carbonate of ammonia
and become carbonate of magnesia when mixed with such liquids), in
the manner and for the objects herein set forth.
In witness whereof, I, the said Henry Young Darracott Scott,
have hereunto set my hand and seal, the Twelfth day of January,
in the year of our Lord One thousand eight hundred and seventy-
five.