Improvements in Apparatus for Drying Superphosphates and the like.
Year: 1895

page_text: Date of Application, 27th Nov., 1895
Complete Specification Left, 25th Aug., 1896-Accepted, 27th Nov. 1806
PROVISIONAL SPECIFICATION.
Improvements in Apparatus for Drying Superphosphates and
the like.
I JAMES YATE JOHNSON of 47 Lincoln's Inn Fields in the County of London
Gentleman do hereby declare the nature of this invention (which has been com-
municated to me from abroad by The Verein Chemischer Fabriken of Mannheim
in the Empire of Germany) to be as follows:-
Hitherto, in order to dry superphosphates as they come from the works, it has
been usual to cause the superphosphates to slide down shaking or rocking inclined
plates into a shaft-furnace kiln or oven either heated direct by a fire below, or fed
with the waste gases from a separate external furnace.
This method, however, is not free from certain disadvantages.
The material to be dried, in dropping upon the first of the set of plates, is
unequally divided, being partly in the condition of grit, and partly in large lumps;
this necessitates an extremely violent shaking of the metal plate, the coarser
material being imbedded in the more finely divided material, so that its progress
is impeded and, as it remains upon the plate longer than necessary in consequence,
it clogs the said plate, thereby interfering more or less with its proper operation..
In addition to this, the descent of the material is extremely slow and laborious
and, whereas the finer particles thereof become dried before they have had time to
pass the first of the plates, the large-sized lumps continue much longer in a soft
and semi liquid state. In some cases, indeed, the material becomes clotted in the
furnace, so that it forms additional lumps, with the result that in the product
leaving the furnace there are more lumps than first entered the furnace. In
many cases, too, the metal plates have to be displaced and readjusted according
to the quality of superphosphates to be dried, and in some instances the
material simply will not descend. It follows that in the subsequent stage the
material has to be collected with the moist lumps in it, and therefore the utility
of the furnace is greatly reduced and the object of the whole apparatus practically
nullified, since the desiccation of those lumps is the main desideratum. If the
operation be continued until the lumps are dry, the quantity of work, or "yield"
obtained from the furnace, is insufficient, and one particular drawback attaching
to this latter alternative is, that the finely divided material is superheated, with
the result that part of the phosphoric acid, which should be soluble in water,
becomes either totally insoluble or, at all events, capable of dissolving but with
such difficulty as to render an analysis by the usual methods impracticable. The
consequence of all this is that, while a very large amount of mechanical power has
to be expended in producing the very energetic oscillatory motion which it is
required to impart to the metal plates, the several parts of machinery are liable
to very rapid wear, both owing to the excessive speed of motion maintained, and
the uncommonly large quantities of fuel consumed. The final product moreover is
generally dried in an uneven and unsatisfactory manner, and deprived of part of
its ready solubility.
"
The arrangement forming the subject of this invention obviates the inconveniences
stated, for it enables thoroughly, and uniformly, dried, material to be obtained,
which retains its normal solubility undiminished, while necessitating a considerably
Jess consumption of mechanical power and fuel, whilst increasing the working
capacity or useful effect of the furnace.

page_text: The invention consists in arranging in the shaft furnace or drying oven or kiln a
number of slightly inclined sieves or grates, instead of the usual corrugated sliding
surfaces, arranged in tiers, steeply inclined and adapted to be set in oscillatory
motion by mechanical means; the said sieves or grates being provided on their
upper surfaces with vertical projections blades, pins, or lugs. These sieves or
grates or sifting frames may, for example, be formed of barbed wire, or consist of
perforated metal plates, the perforations of which have raised sharp edges, not
unlike those of a grater. The most advantageous form of sifting frames for the
improved arrangement is one resembling a harrow in shape, with teeth pointing
upwards. These harrows are preferably constructed with perforations or interstices
larger than the ribs or solid portions carrying the teeth.
The material introduced into the drying shaft or shoot and which, preferably,
has been roughly or superficially divided, either before being placed in the filling or
charging orifice of the shoot or shaft, or while in the act of entering the same,
drops upon the sifting frames or grates, which are furnished with pins, points, or
lugs, as stated, and are set in oscillatory motion. The grates, or harrows, upon
receiving the material thus dropped on to them, sift it instantly, the fine powder,
or flour, falling through the interstices direct, from one sieve or harrow to the next,
thus traversing the whole furnace kiln or oven and filling it with dust. This dust
is permeated by the rising hot air, and rapidly dried, after which, as it descends to
to the bottom, it is, with the same rapidity, removed from the furnace. The
comparatively large lumps are retained somewhat longer upon the sieves which
are but slightly inclined, and, whilst they remain thereon, they are moved to and
fro, and, in such motion, reduced by the points, or lugs. As therefore, they slide
from one sieve, grate, or harrow to the next, they gradually decrease in size and
are, at the same time, separated from the small fragments falling through the
interstices.
Half dried lumps do not reach the sole-plate of the furnace kiln or oven at all,
and the extremely fine division of the material enables it to be treated at a
temperature at which the decomposition of the dry material cannot take place.
The complete process is, by such means, moreover, carried out in a rapid and
reliable manner, while the powdered superphosphate thereby obtained is of a
uniform nature and quality.
The construction and arrangement of the furnace kiln or oven to be employel in
carrying out this process may be heated either by means of steam coils, or by the
direct action of fire, or by the waste gases of an external furnace or some extraneous
source of heat, or indeed, by air heated in any convenient manner.
The sifting frames or plates need not, as has been usual in other ovens, have
their angle of inclination varied or adjusted according to the nature of the material.
to be treated in each case. In the improved arrangement they may at all times
retain a uniform angle of inclination, nor do they require any particularly powerful
shaking, inasmuch as they do not become clogged. Besides such lumps as there
are do not get embedded in the material, and therefore remain freely movable along
the sifting frame, and slide down even a slightly inclined surface with ease.
As regards temperature, that of exhaust steam is quite sufficient. It should
not, at all events, very far exceed 100° Centigrade, seeing that the drying action
is assisted as it is, by the state of fine division in which the material is supplied to
the furnace kiln or oven, while, by not further raising the temperature, the
solubility of the product in water is fully retained.
Dated this 27th day of November 1895.
JOHNSONS & WILLCOX,
47 Lincoln's Inn Fields, London, W.C., Agents.

page_text: Improvements in Apparatus for Drying Superphosphates and
the like.
I, JAMES YATE JOHNSON, of 47 Lincoln's Inn Fields, in the County of London,
Gentleman, do hereby declare the nature of this invention (which has been com-
municated to me from abroad by The Verein Chemischer Fabriken, of Mannheim,
in the Empire of Germany) and in what manner the same is to be performed
to be particularly described and ascertained in and by the following statement:-
Hitherto, in order to dry superphosphates, as they come from the works, it has
been usual to cause the superphosphates to slide down shaking or rocking inclined
metal plates into a shaft furnace, kiln, or oven, either heated directly by a fire
below, or fed with the waste gases from a separate external furnace.
This method, however, is not free from certain disadvantages.
The material to be dried, in dropping upon the first of the set of plates, is
unequally divided being partly in the condition of grit, and partly in large lumps.
This necessitates an extremely violent shaking of the metal plate the coarser
material being embedded in the more finely divided material so that its progress
is impeded and, as it remains upon the plate longer than necessary in consequence,
it clogs the said plate, thereby interfering more, or less with its proper operation.
In addition to this, the descent of the material is extremely slow and laborious
and, whilst the finer particles thereof become dried before they have had time to
pass the first of the plates, the large-sized lumps continue much longer in a soft
and semi-solid or semi-liquid state. In some cases, the material becomes clotted
in the furnace, so that it forms additional lumps, with the result that in the
product leaving the furnace there are more lumps than first entered the furnace.
In many cases, too, the metal plates have to be displaced and readjusted according
to the quality of superphosphates to be dried and in some instances the material
simply will not descend. It follows that in the subsequent stage, the material
has to be collected with the moist lumps in it, and therefore the utility of the
furnace is greatly reduced and the object of the whole apparatus practically
nullified, since the desiccation of those lumps is the main desideratum.
operation be continued until the lumps are dry, the quantity of work, or "yield,"
obtained from the furnace, is insufficient; and one particular drawback attaching
to this latter alternative is, that the finely divided material is superheated, with
the result that part of the phosphoric acid which should be soluble in water,
becomes either totally insoluble, or at all events, capable of dissolving but with
such difficulty as to render an analysis by the usual methods impracticable. The
consequence of all this is that while a very large amount of mechanical power
has to be expended in producing the very energetic oscillatory motion which it is
required to impart to the metal plates, the several parts of machinery are liable
to very rapid wear, both ing to the excessive speed of motion maintained and
the uncommonly large quantities of fuel consumed. The final product moreover
is generally dried in an uneven and unsatisfactory manner, and deprived of part of
its ready solubility."
If the
The arrangement forming the subject of this invention obviates, the incon-
veniences stated, for it enables thoroughly, and uniformly, dried material to be
obtained, which retains its normal solubility undiminished, the arrangement further
necessitating a considerably less consumption of mechanical power and ſuel, whilst
increasing the working capacity, or useful effect, of the furnace.
The invention consists in arranging in the shaft-furnace, or drying oven, or kiln,
a number of slightly inclined sieves, or grates, one above the other, instead of the
usual corrugated sliding surfaces arranged in tiers, steeply inclined and adapted to

page_text: be set in oscillatory motion by mechanical means. The said sieves, or grates, are
preferably provided on their upper surfaces with vertical projections, blades, pins,
or lugs. These sieves, or grates, or sifting frames, may for example, be formed of
barbed wire, or consist of perforated metal plates, the perforations of which have
raised sharp edges, not unlike those of a grater. The most advantageous form of
sieve grate or sifting frame for the improved arrangement is one resembling a
harrow in shape, with teeth pointing upwards, and preferably constructed with
perforations, or interstices larger than the ribs or solid portions, carrying the
teeth.
The material introduced into the drying shaft, or shoot, and which preferably
has been roughly, or superficially, divided, either before being placed in the filling,
or charging, orifice of the shoot, or shaft, or while in the act of entering the same
drops upon the sifting frames, or grates, which are furnished with projections,
blades, pins, or lugs, as stated, and are set in oscillatory motion. The sieves,
grates, or harrows upon receiving the material thus dropped on to them, sift it
instantly, the fine powder, or flour, falling through the interstices direct, from one
sieve or harrow to the next, thus traversing the whole furnace kiln or oven and
filling it with dust. This dust is permeated by the rising hot air, and rapidly dried,
after which, as it descends to the bottom, it is, with the same rapidity removed
from the furnace. The comparatively large lumps are retained somewhat longer
upon the sieves which are but slightly inclined, and, whilst they remain thereon,
they are moved to and fro and, by such motion they are reduced by the pro-
Jections, blades, pins, or lugs. As, therefore, they slide from one sieve, grate, or
barrow to the next, they gradually decrease in size and are, at the same time,
separated from the small fragments falling through the interstices.
Half dried lumps do not reach the sole-plate of the furnace kiln or oven at all
aud the extremely fine division of the material enables it to be treated at a
emperature at which the decomposition of the dry material cannot take place.
The complete process is, by such means, moreover, carried out in a rapid, and
reliable manner, while the powdered superphosphate obtained is of a uniform
nature and quality.
The furnace kiln or oven to be employed in carrying out this process may be
heated either by means of steam coils, or by the direct action of fire, or, by the
waste gases of an external furnace or some extraneous source of heat, or, by air
heated in any convenient manner.
The sieves grates or sifting frames in the improved arrangement may at all
times retain a uniform angle of inclination and need not, as has been hitherto
usual have their angle of inclinations varied, or adjusted, according to the nature
of the material to be treated in each case, nor do the said sieves, grates, or sifting
frames require any particularly powerful shaking, because they do not become
clogged, and such lumps as there may be do not get embedded in the material,
and therefore remain freely moveable along the sieves, grates, or sifting frames,
and slide down even a slightly inclined surface with ease.
As regards temperature, that of exhaust steam is quite sufficient. It should not,
at all events, very far exceed 100° Centigrade, seeing that the drying action is
facilitated by the state of fine division in which the material is supplied to the
furnace kiln or oven, while, by not raising the temperature above this, the solubility
of the product in water is fully retained.
In the accompanying drawing Figure 1 shows an example of drying apparatus
constructed according to this invention and Figure 2 shows in perspective a drying
grate or sieve of the said apparatus drawn to a larger scale.
a are the drying grates or sieves to which a shaking motion is imparted by the
mechanism bc operated from the pulley c¹. The material to be dried is supplied
to the hopper d and by means of wings or flaps e is fed on to the uppermost grate
or sieve a. After passing down through the grates or sieves a in succession the
material falls onto guide plates arranged in steps from the lowest plate of which
it passes out of the apparatus into a trolley or the like g.

page_text: A steam coil is here shown as the means employed for heating the shaft
furnace or kiln.
The dotted lines i in Figure 2 indicate the vertical projections pins or lugs with
which the grates or sieves are preferably provided.
The plates I have described may be used with any other suitable drying furnace
or kiln the invention not being limited to the particular arrangement shown in the
drawing.
Having now particularly described and ascertained the nature of this inven
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. In a shaft furnace oven or kiln for drying superphosphates or the like an
arrangement of slightly inclined and superposed grates or sieves provided with
means for shaking them substantially as and for the purpose set forth.
2. In a shaft-furnace oven or kiln for drying superphosphates or the like an
arrangement of slightly inclined and superposed grates, sieves, or harrows,"
provided with projections, blades, pins, lugs or the like on their upward surface,
and provided with means for shaking them substantially as and for the purposes
herein before described.
Dated this 25th day of August 1896
JOHNSONS & WILLCOX,
47 Lincoln's Inn Fields, London, W.C., Agents.