Process and Apparatus for the Drying and Disintegration of Superphosphates.
Year: 1896

page_text: Date of Application, 5th Nov., 1896-Accepted, 30th Jan., 1897
COMPLETE SPECIFICATION.
Process and Apparatus for the Drying and Disintegration of
Superphosphates.
We, OSCAR HEYMANN, of 31 Junkernstrasse, Breslau Germany Manufacturer,
and AUGUST NITSCH, Works Director, of 21 Michaelisstrasse, Breslau Germany,
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 disintegration of lumps of superphosphates is difficult, because, under the
influence of mechanical treatment, the composition of the material is changed,
whereby a delay is caused in the working; but the principal disadvantage is the
decrease in the quality of the products.
Superphosphate is made, as is well known, by mixing finely ground raw phosphate
and sulphuric acid. Tribasic phosphated calcium is thereby changed into mono-
basic phosphated calcium, heat being set free. The mass becomes stiff and forms
large hot porous lumps, which have hitherto been allowed to cool; as a consequence,
the greater amount of water remained enclosed therein, and the material became
hard. In order to evaporate the superfluous water, the superphosphate is treated
in kilns at present, or it is placed in heaps, in order to let the air dry it.
material is afterwards disintegrated to make it marketable.
The
The material is disintegrated at present by throwing it against oblique wire
sieves, the fine grain is sieved off, the remaining large nuts or lumps are further
disintegrated manually by shovelling or beating and the sieving is repeated. In
other cases the lumps of superphosphate are disintegrated in disintegrators or
rollers etc., or the material is placed on rocking sieves and sieved off.
However, the latter methods can be only used when the material is very dry,
because superphosphates are extremely sensitive to pressure, blows and friction.
When thus treated water appears at the surface immediately and with it free
phosphoric acid, both substances render the lumps or nuts slimy, and unsuitable
for further treatment.
Kiln drying is expensive and has various disadvantages, such as the setting
free of fluoric and other corroding acids, which destroy all vegetable and animal
life; and, further, as the kiln-drying causes the formation of metaphosphoric acid,
which is insoluble in water, and therefore reduces the quality of superphosphates,
it has not fou ready introduction. In most cases the shovelling up of the heaps
of superphosphate is still used to produce a material which is more easily
treated, and also more valuable, and the use of machinery is avoided.
Now, this invention is designed to obviate the above disadvantages and to dry
and disintegrate the superphosphates simultaneously.
In order that my invention may be the better understood, I now proceed to
describe the same reference being had to the accompanying drawings and to the
letters and figures marked thereon.
Figure 1 is a front elevation of the apparatus for the drying and simultaneous
disintegration of freshly produced superphosphates, and for pulverising the dried
superphosphates.
Figure 2 is a side elevation of the same.
The process is essentially as follows:-
As before stated during the mixing of raw phosphates with sulphuric acid and

page_text: during the chemical reaction which is caused thereby, heat is set free, the mass
becomes stiff at a temperature of about 96° C. and forms large moist lumps. The
latter fall easily to pieces when in this condition; they are therefore, according to
my invention, lifted immediately by means of an elevator E and transferred
through a shoot R' into a cylinder C, the shell of which is formed of wire netting
of suitable mesh, in which the material is disintegrated.
During this operation a hot current of air may be introduced in special cases,
which, rising, passes through the cylinder C and surrounds the lumps during the
disintegration. As the lumps gain in surface in proportion to their volume as the
disintegration proceeds, they readily yield the superfluous water to the air under
the influence of the remaining heat of reaction, and become dry.
The dried and disintegrated material falls through the meshes of the sieve shell
of the cylinder C₁ into a shoot and is ready for market after cooling.
The
process may be extended by feeding the dried material to a second cylinder C
in which it is disintegrated to the desired degree of fineness.
The material falls through the meshes of the sieve drum C into the sacks attached
to the funnel T. Pieces which do not become disintegrated. pass through the
double rolls W and the channel R, back to the elevator E, and into the cylinder C,
where they are mixed in their present form with the great mass of fresh material
introduced, and are readily disintegrated and sieved off.
In order to keep the meshes of the sieving shells free from choking, beaters K
to K are provided at suitable places, and actuated by rods and fixed to the
cylinders. The orifices of the air admission tubes are protected by shields y
against becoming choked by the material treated.
These processes have not the slightest injurious effect on the material treated
and the arrangement of devices excels all known apparatus as regards capacity of
production.
The angle at which the cylinders are placed during operation is adjustable by a
device S in order to lengthen or shorten, according to the nature of the material
treated, the period during which the material remains in the cylinders.
The transmission of motion to the various parts of this apparatus is arranged so
that by engaging or disengaging the driving wheel A the whole apparatus or any
cylinder may be placed into operation or out of it.
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 :-
1st. A process for the drying and disintegration of superphosphates, in which
the superphosphate which has been dried or become warm by the heat of reaction
is fed through oblique sieve drums, which are provided advantageously with heating
arrangements and rollers, and in which, if desired, a current of hot air is fed
against the descending finely divided superphosphate.
2nd. Devices for carrying out the process claimed in Claim 1 which may be
arranged separately, consisting of an elevator E feeding the superphosphate to
oblique rotary sieving cylinders C and C₁, provided with beaters K-K, from
which it falls either into a shaft, provided with hot air pipes, for immediate
removal, or passes over rollers W, whence it is taken up again by the elevator for
a repetition of the sieving process.
Dated this 5th dow of Nanomaan 1000
FELL & JAMES,
Agents for the Applicants.