IMPROVEMENTS IN THE TREATMENT OF PHOSPHATIC AND NITROGENOUS SUBSTANCES, AND IN THE MANUFACTURE OF MANURES THEREFROM."
Year: 1882

page_text: LETTERS PATENT to Henry Young Darracott Scott, of Sydenham, in the
County of Kent, Major General, C.B., for an Invention of "IMPROVEMENTS
IN THE TREATMENT OF PHOSPHATIC AND NITROGENOUS SUBSTANCES, AND
IN THE MANUFACTURE OF MANURES THEREFROM."
PROVISIONAL SPECIFICATION left by the said Henry Young Darracott
Scott at the Office of the Commissioners of Patents on the 21st January
1882.
.
HENRY YOUNG DARRACOTT SCOTT of Sydenham in the County of Kent,
Major General C.B. "IMPROVEMENTS IN THE TREATMENT OF PHOSPHATIC AND
NITROGENOUS SUBSTANCES, AND IN THE MANUFACTURE OF MANURES THEREFROM."
The object of this invention is to render mineral and animal phosphates more
efficacious for agricultural purposes, and to prepare manures from them and from
gas liquor, or from refuse materials containing nitrogen in a cheap and efficient
manner.
Bone and other phosphates are now either sent into the market granulated or
ground to a powder, or have their phosphoric acid set free from insoluble combi-
nations by acting upon them with mineral acid, such as oil of vitriol. From this
latter mode of treatment an acid condition results, which unless neutralized by the
soil is injurious to vegetable life. When the phosphoric acid is thus rendered
soluble, however, a better distribution through the soil is claimed for it, than when
the phosphoric acid applied to the soil is bound up in more or less insoluble
combinations. Again in rendering the ammonia of gas liquor available as a
portable manure, the ammonia is usually obtained by distillation as a sulphate, and ·
at various times it has been proposed to produce from gas liquor ammoniacal
phosphate of magnesia, but although the valuable manurial properties of this salt
have been known to agricultural chemists, the methods proposed for preparing
the compound have not been successful as manufacturing processes, nor has the
manurial efficacy of magnesia, as one of the important elements of a manure, been
generally recognised.
According to my invention the ammonia is recovered from the gas liquor
without resorting to distillation, and the substance magnesia by means of which
it is removed is employed to destroy the acidity resulting from rendering
phosphates soluble, without depriving thein of that comparatively small degree of
solubility which is essential to the perfect nutrition of plants.

page_text: In carrying out my Invention I take the phosphate to be operated upon, and
after reducing it to a powder, I treat it with oil of vitriol in the ordinary manner,
with the exception that I generally employ a sufficiency of that acid to set the
whole of the phosphoric free from its base, in lieu of leaving it as a monophosphate
of calcium.
<
I then take magnesia prepared by washing out the lime from calcined dolomite
with water, or in other solvent, or prepared in any other convenient manner, and
I convert it into carbonate of magnesia by passing through it, whilst in a state of
suspension in liquid (which liquid may be the gas liquor operated upon) carbonic
acid derived from a process to be immediately described. The carbonate of
magnesia formed by this means is then agitated with the gas liquor for some time,
and during the process of agitation the carbonate of ammonia dissolved in the
-liquid is absorbed in combination with the carbonate of magnesia as a chemical
compound.
As soon as saturation has taken place, I separate the salt formed (which I will
call a double carbonate) by decantation and filtration, and to the liquid which
flows off I add magnesia or its carbonate, and phosphoric acid in the proportion
which I judge to be sufficient for precipitating, as ammoniacal phosphate of
magnesia, the ammonia still remaining in the liquid of magnesia. This precipitate
I also collect by decantation or filtration and I add it to the double carbonate
obtained as above, having first expelled from this latter the carbonic acid, by the
addition to it of sulphuric or phosphoric acid. The combination of the salts thus
obtained forms an excellent manure. In cases in which nitrogen exists in the raw
phosphatic substance employed as in bones or phosphatic guano, and if I require
no additional nitrogen for the manure (as when
derive this element from sewage
sludge, foecal matter or other nitrogenous refuse) I neutralize the acidity produced
by bringing the phosphatic substance into solution, by simply adding thereto
magnesia or its carbonate.
I have assumed in the foregoing description of my invention that phosphate of
lime is the chief element of the phosphatic mineral employed, and sulphuric acid the
acid used, but an analogous process may be adopted when phosphates of iron or
alumina are the chief components of the mineral, and hydrochloric acid the acid
employed. These substances however yield generally inferior results, being more
uncertain in their action, chiefly owing, probably, to the insolubility of these
phosphates as compared with phosphate of magnesia. The latter salt I may
mention is sufficiently insoluble to prevent its being washed out of reach of the
roots of plants by heavy rains and yet it is soluble enough for thorough distri-
bution through the soil and for all the wants of vegetation. This is an important
advantage.
I may sometimes use dolomitic lime to neutralize the acids resulting from, or
employed in, the treatment of the phosphatic mineral, instead of employing magnesia
for that purpose; or I may use the double carbonate above referred to, or again
I sometimes effect the neutralization in part by crude potashes, pearl ash or soda;
and in speaking of neutralization I wish it to be understood that for manures to
be used on soils when acidity is not prejudicial to vegetation, because of its
immediate neutralization in the upper layers as on a chalky soil, I carry the
neutralization in the manure itself to the point which will leave the compound in
a tolerably dry condition fitted to run from a drill.
Sometimes also I remove, by means of water, the sulphates or chlorides which
result from the neutralization of the acids, and I crystallize them out for other
purposes; and in cases in which there might be notable loss of phosphoric acid,
(as for instance when phosphate of magnesia is the result of the neutralization)
from the comparative solubility of the of the salt, I precipitate the phosphoric acid
from the watery solution which is removed from the phosphate of magnesia by
the addition to such liquid of soluble salts of alumina and iron.

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 21st July 1882.
HENRY YOUNG DARRACOTT SCOTT of Sydenham in the County of Kent
Major General C.B. " IMPROVEMENTS IN THE TREATMENT OF PHOSPHATIC AND
NITROGENOUS SUBSTANCES AND IN THE MANUFACTURE OF MANURES THEREFROM."
The object of this Invention is to render mineral and animal phosphates more
efficacious than heretofore for agricultural purposes, and to prepare manures from
them and from gas liquor or from refuse materials containing nitrogen, in a cheap
and efficient manner.
•
Bone and other phosphates are now either sent into the market granulated or
ground to a powder, or have their phosphoric acid set free from insoluble com-
binations by acting upon them with mineral acid such as oil of vitriol. From this
latter mode of treatment an acid condition results, which unless neutralized by the
soil, is injurious to vegetable life. When the phosphoric acid is thus rendered
soluble however, a better distribution through the soil is claimed for it than when
the phosphoric acid applied to the soil is bound up in more or less insoluble com-
binations. Again, in rendering the ammonia of gas liquor available as a portable
manure, the ammonia is usually obtained by distillation as a sulphate, and at
various times it has been proposed to produce from gas liquor ammoniacal phosphate
of magnesia, but although the valuable manurial properties of this salt have been
long known by agricultural chemists, the methods proposed for preparing the com-
pound have not been successful as manufacturing processes, nor has the manurial
efficacy of magnesia itself, as one of the important elements of a manure, been
generally admitted.
According to my Invention, the ammonia is recovered from the gas liquor with-
out resorting to distillation, and the substance magnesia, by means of which it is
removed, is employed to destroy the acidity (resulting from rendering phosphates
soluble) without depriving the phosphatic compound of that comparatively small
degree of solubility which is essential to the perfect nutrition of plants, by its
means.
In carrying out my Invention I take the phosphate to be operated upon, and
after reducing it to a powder, I treat it with oil of vitriol in the ordinary manner,
with the exception that I generally employ when phosphate of magnesia is the sole
phosphate aimed at in the production of the manure, a sufficiency of that acid to
set the whole of the phosphoric acid free from its base, in lieu of leaving it as a
monophosphate of calcium.
I then take magnesia, prepared by washing out with water, the lime from calcined
dolomite or by using other solvents, or prepared in any other convenient manner,
and I convert it into carbonate of magnesia by passing through it whilst in a state
of suspension in liquid, (which liquid may be the gas liquor operated upon) carbonic
acid, derived from a process to be immediately described. The carbonate of
magnesia formed by this means is then agitated with the gas liquor for some time,
and during the process of agitation, the carbonate of ammonia dissolved in the
liquid is absorbed, in combination with the carbonate of magnesia, as a chemical
compound.
I sometimes apply the process to gas liquor during the manufacture of the gas
before the gas liquor is removed from the purifiers, magnesia or dolomitic lime being
substituted in them for ordinary lime.
As soon as saturation in whole or in part bas taken place, I separate the salt formed
(which I will call a double carbonate) by decantation and filtration, and to the
liquid which flows off I add magnesia or its carbonate and phosphoric acid in the
proportion which I judge to be sufficient for precipitating, as ammoniacal phosphate
of magnesia the ammonia still remaining in the liquid.
I do not, however, claim for the precipitation of ammonia as an ammoniacal

page_text: phosphate of magnesia, that object having been already the subject of various
Patents, which though they have been commercially unsuccessful, indicate a true
and rational principle of proceeding but I limit my claim to the treatment of the
residue of the ammonia in gas liquors and other ammoniacal liquids after the use
with them of carbonate of magnesia as above described. The precipitate thus
obtained I also collect by decantation or filtration, and I add it to the double
carbonate obtained as above, having first expelled from this latter the carbonic acid
by the addition to it of a mineral acid such as sulphuric or phosphoric acid. (The
carbonic acid expelled I employ to supply carbonic acid to the magnesia as above
. mentioned). The combination of the salts. thus obtained forms an excellent manure.
In cases in which nitrogen exists in the raw phosphatic substance employed, as
in bones or phosphatic guano, and if I require no additional nitrogen for the manure
(as when I derive this element from sewage sludge, foecal matter, or other nitro-
genous refuse) I neutralize the acidity, produced on bringing the phosphatic
substance into solution by simply adding thereto magnesia or its carbonate, or in
lieu of magnesia or conjointly with it, I add to the dissolved acid, guano or bones,
the said sewage sludge, when the alkaline earths which are almost invariably present
with sewage sludge, act as the neutralizing base.
If however, phosphoric acid has been added to and precipitated from the sewage
water from the soluble condition and if it already exists therefore in the sludge
in the condition at which I aim, (as for instance, when acid phosphate of lime is
neutralized by lime) no further addition of lime or magnesia is absolutely
necessary. Under such circumstances there will always be present, carbonates of
the alkaline earths which will act as bases, and although the precipitated phosphate
of lime is not so soluble as precipitated phosphate of magnesia, yet in the presence
of the carbonic acid which results from the decomposition of the organic matter,
precipitated phosphate of lime is sufficiently soluble to become a highly efficacious
fertilizer.
Unless the sludge is to be dried by heat, and there is consequently no danger of
a loss of phosphoric acid, the mixture should be left with an alkaline reaction. In
the preparation of sludge to be used for the purpose here contemplated, the value
of the process is sometimes much enhanced by proceeding as follows. I add to the
sewage water to be treated, at the upper extremity, if possible, of a system of sewers,
a regulated quantity of phosphate of magnesia, by means of some mechanical
arrangement and a flushing tank and according to the ascertained proportion of
ammonia which exists in the sewage.. (It is manifest that I must prefer for the
treatment, sewage which has been collected on the separate system, both as being
stronger sewage and as being freer from detritus which degrades the resulting
manure. Indeed in ordinary sewage the process must generally be unsuitable
ammonia being present in too small a proportion, and degrading substances being
present in such abundance)
By this means I procure that the ammoniacal sewage water shall be thoroughly
agitated with the phosphate of magnesia, and time is allowed for the formation
of the crystalline precipitate of ammoniacal phosphate of magnesia. When the
sewage water arrives at the tanks, I procure the admixture with it of a sufficient
quantity of milk of lime to ensure the precipitation of all the phosphoric acid,
either resulting from the phosphates of the urine of the sewage or from the partial
solubility of the phosphate of magnesia added to it. In this manner if the sewage
be concentrated, I obtain a notable quantity of ammoniacal phosphate of magnesia
mixed with the sewage. This method of procedure I may observe contributes also
in a marked manner to the cleansing of the sewers.
In the subsequent treatment of the sludge thus procured I add phosphoric acid
in such proportion as may be necessary to expel the carbonic acid from the sludge
or I may add an additional quantity of phosphoric acid and neutralize it with
magnesia or lime so as to procure a larger proportion of phosphate with the
sludge.
In case the sludge is to be dried by the application of pressure which would

page_text: cause the soluble matters to pass off in solution I am careful to make the sludge
alkaline (which may be done either by the addition of an alkaline earth, such as
lime, or by that of the alkaline earth magnesia, and some gas liquor which contains
the alkali ammonia, this is again referred to below), and I also add to the expressed
water, lime or alumina, or both to precipitate any phosphoric acid, and I add the
precipitate obtained to the manure.
For the purpose of facilitating the treatment of the sludge I sometimes raise it
to boiling temperature before passing it through the press, but this is essential
only when little mineral matter is present.
If on the other hand, I carry out the desiccation of the sludge on a drying floor,
I sprinkle over it such a quantity of kainit or sulphate of potash or soda or chloride
of potassium or in the absence of carbonate of lime, of sulphuric acid as is necessary
to prevent loss of ammonia in drying.
.I may sometimes employ calcined magnesian lime, or dolomite, for forming the
magnesian phosphates for reasons of economy, and for the same reasons I may use
soluble phosphate of lime in lieu of phosphoric acid in the above operations.
It is generally unimportant whether I add the phosphoric acid to the compound
containing the neutralizing base, or the base to the acid. In dealing with sludge
obtained by precipitation with phosphate of alumina the process followed is
analogous to that above described I find it best to add to the sludge a sufficiency
of phosphoric acid to convert the carbonates present into phosphates, but if on the
other hand the precipitation has been so arranged as to procure the deposition of
the sludge free from any very notable proportion of carbonates of the alkaline
earths, I then add the quantity of phosphoric acid, which I judge to be sufficient
and neutralize the acid with an alkali or alkaline earth according to the system
of drying to be followed-In using a press, the alkali (excepting in the case of
ammonia used together with phosphoric acid and magnesia, as is elsewhere
mentioned) is an unsuitable addition on account of its solubility.
It will appear from the foregoing that whilst the precipitates ordinarily obtained
from sewage can be made available for the purposes of my Invention, and the
presence of carbonate of lime in the sludge used, is not a disadvantage up to a,
certain point, yet that those sludges in which large quantities of carbonate of lime,
or of silicious and aluminous constituents prevail are less suitable for my purposes,
because these must generally be considered inert materials in an agricultural point
of view. I wish to point out therefore, that the character of the sludge, is, in
reference to my Invention, of more importance than the clearness of the effluent
produced, and I so adjust the precipitants as to reduce the valueless ingredients of
the sludge, as far as can be done, consistently with causing its deposition in the
tanks provided for its reception, and when further clarification is necessary I effect
this by a secondary_precipitation in additional tanks, as for instance with lime or
lime and clay, and I treat this deposit separately.
I have assumed in the foregoing description of my Invention that phosphate of
lime is the chief element of the phosphatic mineral employed and sulphuric acid
the acid used but an analogous process may be adopted when phosphates of iron or
alumina are the chief components of the mineral, and hydrochloric acid the acid
employed-These substances however yield generally inferior results, being more
uncertain in their action, chiefly owing, probably, to the insolubility of these
phosphates as compared with phosphate of magnesia Where hydrochloric acid is
the acid used, I prefer to bring about the neutralization by means of crude potash
or pearl ash or by soda to avoid the deliquescence which results from the presence
of chlorides of the alkaline earths. The phosphate of magnesia I may mention is
sufficiently insoluble to prevent its being washed out of reach of the roots of plants
by heavy rains, and yet it is soluble enough for thorough distribution through the
soil and for all the wants of vegetation. This is an important advantage.
In fact phosphate of magnesia is so soluble, that in certain cases, when a filter
press is to be used for expressing the liquid from the sludge, I add a small quantity
of gas liquor to the watery sludge, as above indicated, which renders the phosphate

page_text: of magnesia insoluble during the operations of pressing. The quantity of ammoniacal
water in the shape of gas liquor or other liquid containing carbonate of ammonia or
sulphide of ammonium which is added, depends on the amount of phosphoric acid
used, and should be sufficient to supply one chemical equivalent of ammonia to every
chemical equivalent of phosphoric acid.
I have already referred to my occasional use of dolomitic lime to neutralize the
acids resulting from, or employed in the treatment of the phosphatic mineral, instead
of employing magnesia for that purpose; and I may use the double carbonate of
ammonia and magnesia above referred to for this object; or again I sometimes effect
the neutralization in part by crude potashes, pearl ash, or soda, separately or in
combination with each other or with magnesia or lime, and in speaking of neutrali-
zation I wish it to be understood that for manures to be used on soils when acidity
is not prejudicial to vegetation, because of its immediate neutralization on application
in the upper layers of soil, I carry the neutralization in the manure itself to the
point which will leave the compound in a tolerably dry condition fitted to run
from a drill.
Sometimes, also, I remove by means of water the sulphates or chlorides which
result from the neutralizing action of the acids, and I crystallize them out for other
purposes, and in cases in which there might be notable loss of phosphoric acid (as
for instance when phosphate of magnesia is the result of the neutralization) from
the comparative solubility of the salt, I precipitate the phosphoric acid from the
watery solution, which is removed from the solid phosphate of magnesia by the
addition to such liquid of soluble salts of alumina and iron or by the addition to
the watery sludge to which phosphate of magnesia has been added of a small
quantity of alkali in the shape of waste ammoniacal water as already intimated
above.
Having now described the nature of my Invention and the manner of performing
the same, I declare that what I claim as the Invention to be protected by the
hereinbefore in part recited Letters Patent is...
First: The production of a valuable manure by acting on the double carbonate
of magnesia and ammonia with phosphoric acid or sulphuric acid or both.
Second-Using the carbonic acid evolved. from the carbonate of magnesia and
ammonia in the preparations of the carbonate of magnesia to be used in the
manufacture of fresh quantities of the double carbonate.
Third The mode of treating ammoniacal liquids, from which part of the
ammonia has been recovered, as the double carbonate of magnesia and ammonia,
with phosphoric acid or phosphoric acid and magnesia for the purposes above set
forth.
Fourth: The employment of alkalis or alkaline earths, or their carbonates, or
sewage sludge whether prepared as above described or not, or other nitrogenous
compounds containing chemical bases in the neutralization of acid compounds of
phosphoric acid in order to prepare therefrom useful manures.
:-
Fifth The employment of lime, gas liquor, or a salt of alumina or iron or a
combination of them, to recover phosphoric acid from liquids which have been
treated with a partially soluble salt of phosphoric acid, to obtain compounds to be
used in the manufacture of manure as hereinbefore described.
In witness whereof I the said Henry Young Darracott Scott have hereunto
set my hand and seal the twenty first day of July in the year of our Lord
One thousand eight hundred and eighty two.