IMPROVEMENTS IN THE TREATMENT OF EXCRETAL AND OTHER REFUSE MATTERS CONTAINING NITROGEN COMPOUNDS FOR THE MANUFACTURE OF MANURES
Year: 1877

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 TREATMENT OF EXCRETAL AND OTHER REFUSE MATTERS CONTAINING
NITROGEN COMPOUNDS FOR THE MANUFACTURE OF MANURES."
Sealed the 18th April 1878, and dated the 27th October 1877.
PROVISIONAL SPECIFICATION left by the said Henry Young Darracott
Scott at the Office of the Commissioners of Patents on the 27th October
1877.
HENRY YOUNG DARRACOTT SCOTT, of Ealing, in the County of Middlesex,
Major-General, C.B. "IMPROVEMENTS IN THE TREATMENT OF EXCRETAL, AND
OTHER REFUSE MATTERS CONTAINING NITROGEN COMPOUNDS FOR THE MANU-
FACTURE OF MANURES."
The chief object of this Invention is the improvement of processes, such as those
now carried out at Rochdale, by which excretal matters are subjected to heat to
drive off the fluid portions thereof and reduce them to solid compounds suitable for
manure.
The excretal matters in these processes are mixed with sufficient sulphuric acid to
fix ammonia which they contain, and they are reduced by evaporation to a con-
centrated and portable condition, but the resulting compounds are too deficient in
phosphates for general fertilizing purposes, and the processes are neither as
economical nor as inoffensive as is desired.
In order to produce with economy from excretal matters which are to be
evaporated to dryness by the above-mentioned process a manure rich in phos-
phates, and also to provide against the discharge of noxious vapours from the
works, I proceed in the following manner:-I take, say, phosphorite in a fine state
of division, and treat it with sulphuric acid, preferably somewhat in excess, and I
thus obtain a mixture consisting chiefly of sulphate of lime and phosphoric acid,
together with some free. sulphuric acid when this acid has been used in excess. .I
remove the phosphoric acid from the insoluble matters by lixiviation, and dry or
calcine the latter. Having introduced the excretal matters into the evaporator, I

page_text: add thereto the phosphoric acid, in the proportion of one equivalent of phosphoric
acid to two equivalents of ammonia contained in the excretal liquids, and by this
means I disengage the carbonic and hydrosulphuric acids, which will pass off from
the evaporator to the furnace, in which the noxious gases are consumed. The
process of evaporation is now commenced, and carried on until the greater portion
of the liquid is driven off. When this stage of the process is reached I introduce
the dried or calcined mineral matters derived from the phosphorite in the propor-
tions suitable for converting the mixture into a powder sufficiently dry to run from
an agricultural drilling machine. The compound thus produced will be found to
contain phosphoric acid and ammonia in the desired proportions for a manure for
general agricultural and horticultural purposes.
The advantages of supplying the phosphates in the manner above described
are,―
1st. That I obtain from the sulphuric acid used in making the phosphoric
acid soluble the greater portion of the neutralizing power required for fixing
the ammonia of the excretal matters, and I thus effect a very important saving
of acid.
2ndly. That I obtain from the phosphoric acid far better deodorization than is got
by the use of sulphuric acid.
3rdly. That the phosphoric acid is present in a neutral and perfectly soluble
condition.
As a further improvement upon this process I propose to conduct the evapo-
ration in two operations:
•
In the one operation I use an evaporator, say No. 1, fitted with arms and
revolving steam pipes, to an extent only possible where a comparatively thin liquid
is the substance dealt with.
In the other operation I employ an evaporator (No. 2), suitable for dealing with
viscous liquids, or pasty or nearly dry substances.
I propose also to commence by subjecting the excretal matters to the action of
the phosphoric acid in a closed vessel heated by steam and fitted with a stirring
apparatus. This vessel is further provided with an outlet to allow the carbonic and
hydrosulphuric acids to be conducted to the furnace, in which they are destroyed.
When the volatile acids are expelled I allow the solid matter to subside, and I draw
off the supernatant liquid and operate upon it in the first of the above-mentioned
evaporators, and I mix the insoluble residues from the phosphorite with the deposit
which has settled down. This deposit is then subjected to filtration to still further
.remove the liquid from it, and this liquid is added to the liquid obtained from
subsidence.
The deposit mixture is finally introduced into the evaporator No. 2, and is therein
dried to the required extent together with the contents of the evaporator No. 1, as
soon as these become too viscous to be further desiccated in that vessel.
'
In cases in which the excretal matters have been much diluted or become weak, I
treat the liquid portion with magnesia (using two equivalents for each equivalent
of ammonia present in the liquid), to which has been added an equal quantity of
phosphoric acid to that necessary for the disengagement of its volatile acids, and I
recover the ammonia as ammoniacal phosphate of magnesia. The ammoniacal
phosphate thus obtained is added to the matters, consisting of the solid excreta
and sulphate of lime, which have been dried in the evaporator No. 2, as above
mentioned.
During the above-described drying operations I sometimes add (for particular
crops) to the excretal matters, kannite or other fertilizers; this will be towards the
end of the evaporation process.
The above modes of dealing with excretal matters are applicable in all cases in
which carbonate and hydrosulphate of ammonia are found, associated with refuse
matters, such, for example, as gas liquor, and also rotten eggs.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Henry Young Darracott Scott in the Great Seal Patent Office on
the 27th April 1878.
HENRY YOUNG DARBACOTT SCOTT, of Ealing, in the County of Middlesex,
Major-General, C.B. "IMPROVEMENTS IN THE TREATMENT OF EXCRETAL AND
OTHER REFUSE MATTERS CONTAINING NITROGEN COMPOUNDS FOR THE MANU-
FACTURE OF MANURES."
The chief object of this Invention is the improvement of processes such as those
now carried out at Rochdale, by which excretal matters are subjected to heat to
drive off the fluid portions thereof and reduce them to solid compounds suitable for
manure.
The excretal matters in these processes are according to the present practice mixed
with sufficient sulphuric acid to fix the ammonia which they contain, and they are
reduced by evaporation to a concentrated and portable condition, but the resulting
compounds are too deficient in phosphates for general fertilizing purposes, and the
processes are neither as economical nor as inoffensive as is desired.
The evaporators used are generally such as to allow the noxious gases driven off
to be passed through a fire to destroy smell, and sometimes condensation of the
vapours is also practised. The evaporator used at Rochdale is a horizontal cylin-
drical vessel having a steam casing or jacket, and fitted with revolving arms and
pipes, as in the Inventions of Forrest and Firmin, also carrying steam.
In order to produce, with economy. from excretal matters which are to be
evaporated to dryness by any of the above-mentioned processes, a manure rich in
phosphates, and also to provide against the discharge of noxious vapours from the
works, I proceed in the following manner :-I take, say, phosphorite in a fine state
of division, and treat it with sulphuric acid, preferably somewhat in excess of the
quantity which is necessary to combine with the lime and other bases present in the
mineral, and I thus obtain a mixture consisting chiefly of sulphate of lime and
phosphoric acid, together with some free sulphuric acid. I remove the phosphoric
acid from the insoluble matters, (chiefly consisting of sulphate of lime, as already
stated) by lixiviation, and dry or calcine the insoluble matters. Having introduced
the excretal matters into the evaporator I add thereto the phosphoric acid in the pro-
portion of one equivalent of phosphoric acid to two equivalents of ammonia contained
in the excretal liquids, and by this means I disengage the carbonic and hydrosulphuric
acids which will pass off from the evaporator to the furnace in which the noxious
gases are consumed. The process of evaporation is now commenced, and carried on
until the greater portion of the liquid is driven off. From time to time I test the
vapours which are driven off to ascertain whether any ammonia is escaping, and if
so, I add some more acid, such as sulphuric or other mineral acid, until the evolution
of ammonia ceases.. When the mixture in the evaporator has reached the pasty
state I introduce the dried or calcined mineral matters derived from the phosphorite
so as to convert the mixture into a powder sufficiently dry to run from an agricul-
tural drilling machine. The compound thus produced will be found to contain
phosphoric acid and ammonia in the best proportions for a manure for general
agricultural and horticultural purposes.
The advantages of supplying the phosphates in the manner above described
are,-
First. That I obtain from the phosphoric acid of the phosphorite when acted
upon by the sulphuric acid the greater portion of the acid required to fix the
ammonia of the excretal matters, and I thus effect a very important saving of
sulphuric acid.
Secondly. That I obtain from the phosphoric acid far better deodorization than is
got by the use of sulphuric acid.
Thirdly. That the phosphoric acid'is present in a neutral and perfectly soluble

page_text: condition, neutrality being a quality of great importance when the manure is used
on soils which do not contain carbonate of lime.
Instead of treating the excretal inatters as a whole I modify my process by
separating the liquid from the solid portions, as hereafter explained, and conducting
the evaporation in two operations.
In the one operation I use an evaporator, say, No. 1, fitted with arms and
revolving steam pipes to an extent only possible where a comparatively thin liquid
is the substance dealt with. These numerous revolving arms and pipes greatly
increase the rapidity of evaporation.
In the other operation I employ an evaporator (No. 2), suitable for dealing with
viscous liquids or pasty or nearly dry substances fitted with revolving machinery such
as not to offer much resistance to a viscous material, and provided with scrapers to
remove the matters which adhere to the sides of the cylinder.
I propose also to commence by subjecting the excretal matters to the action of
the phosphoric acid in a closed vessel heated by steam and fitted with a stirring
apparatus. This vessel is further provided with an outlet to allow the carbonic and
hydrosulphuric acid to be conducted to the furnace in which they are destroyed.
When the volatile acids are expelled I allow the solid matters to subside, and I draw
off the supernatant liquid and operate upon it in the first of the above-mentioned
evaporators, and I mix the insoluble residue from the phosphorite with the deposit
which has settled down. This deposit and insoluble residue may be then subjected
to filtration to still further remove the liquid from them, and the liquid so strained
off may be added to the liquid obtained from subsidence.
The solid mixture is finally introduced into the evaporator No. 2, and is therein
dried to the required extent, together with the contents of the evaporator No. 1, as
soon as these become too viscous to be further desiccated in that vessel.
In cases in which the excretal matters have been much diluted or become weak,
and it is consequently too costly to remove the water by evaporation in No. 1
evaporator, I proceed as follows:-The liquid portion I treat with magnesia (using
two equivalents for each equivalent of ammonia present in the liquid) to which has
been added an equal quantity of phosphoric acid to that necessary for the disen-
gagement of its volatile acids, and I recover the ammonia as ammoniacal phosphate
of magnesia. The ammoniacal phosphate thus obtained is added to the matters
(consisting of the solid excreta and sulphate of lime) which have been dried in the
evaporator No. 2, as above mentioned..
As a modification of this process for dealing with dilute ammoniacal solutions in
lieu of adding the phosphoric acid to the liquid and then removing the acid in
combination with the ammonia present (by the addition of magnesia) as ammoniacal
phosphate of magnesia, I sometimes, after separating the solid matters, subject the
dilute liquid to distillation in a Coffey or other still, and neutralize the ammonia
distilled off by a solution of phosphoric acid instead of by sulphuric acid, as usually
practised. I keep the products of distillation, and also the phosphoric acid, as cool
as possible. The solid matters which have been separated by decantation or filtra-
tion are dried, either alone or mixed, with the phosphate of ammonia resulting from
the distillation process in the before-mentioned evaporator No. 2.
The determination of the method to be adopted for dealing with the liquid
strained or decanted from the solids will manifestly depend on the cost of fuel as
well as the strength of the ammoniacal liquid. When town ashes are cheap and
abundant, and cannot readily be disposed of, more can of course be done in the way
of evaporation than when the ashes find a market.
During the above-described drying operations I sometimes add (for particular
crops) to the excretal matters kannite or. other fertilizers, according to the nature
of the manure required; this will be done towards the end of the evaporation
process.
The above modes of dealing with excretal matters are applicable in all cases in
which carbonate and hydrosulphate of ammonia are found associated with refuse
matters, such, for example, as gas liquor, and also rotten eggs, and I find that by

page_text: adding a certain proportion of gas liquor to focal matters when undergoing dis-
tillation or evaporation I render the process of dealing with them innoxious in a
remarkable degree. The proportion of gas liquor to be added must depend upon
the quantity available, for as it supplies ammonia to the manure and takes
phosphoric acid to neutralize it in proportion to the ammonia, and the quantity of
phosphoric acid so taken is that which enables the nitrogen to be made readily
available for plant life, the gas liquor cannot well be used in excess, and even small
quantities contribute to the destruction of smell as soon as the sulphuretted com-
pounds are discharged.
In the distillation of ammonia into phosphoric acid it is advantageous to conduct
such of the products as may escape condensation in that acid through a vessel con-
taining sulphuric acid to avoid loss of ammonia.
Having now set forth the nature of my Invention of "Improvements in the
Treatment of Excretal and other Refuse Matters containing Nitrogen Compounds
for the Manufacture of Manures," and explained the manner of carrying the same
into effect, I wish it to be understood that I make no claim whatever for any special
evaporating vessels or mechanical contrivances connected with them, but I claim in
the treatment of excretal and other refuse matters containing nitrogen compounds
when subjected to an evaporating or distillatory process the use of phosphoric acid,
in the manner and for the purpose above set forth.
In witness whereof, I, the said Henry Young Darracott Scott, have hereunto
set my hand and seal, the Twenty-sixth day of April, in the year of our
Lord One thousand eight hundred and seventy-eight.
HENRY Y. D. SCOTT. (L.S.).