|Title of Invention||
A PROCESS FOR THE AGGLOMERATION OF MATERIALS THROUGH THE USE OF INFRARED RADIATION AND APPARATUS THEREOF
|Abstract||The invention relates to a process and an apparatus, as well as the variants thereof, which operates continuously or discontinuously for the agglomeration and/or drying of powder materials using selective infrared irradiation on a surface which is continually supplied with renewed powder by a infrared source (14), with eventual addition of liquid agglutinating material via pulverization (17). The process can be performed in sealed conditions or open the atmosphere, with or without the recovery of volatile components. FIG. 1|
|Full Text||The invention refers to a machine that
is specially designed for the agglomeration and/or drying
of powdered materials, through the application of infrared
radiation by a process that will be explained in more
detail further on. Other processes exist in the market
that are used to achieve the same result, such as wet and
dry compacting, pelletization, spray drying, wet extrusion
and wet granulation, which are considered as State of the
Art. Pelletization is a process that is based on forcing a
powder to go through an orifice, thus obtaining a
symmetrical granule in the form of a cylinder. This
process may be carried out either wet or dry format and is
restricted to granules with a cylinder diameter of at
least few millimetres. The dry version lacks versatility,
given that each product will require a different matrix.
Spray drying is a process that requires that the
solid is dispersed and/or dissolved in a liquid to later
be pulverized and exposed to a current of dry air to
remove the water. The obtained granules have a
particularly small particle size of 20 to 300 microns, and
the energy cost for this type of process is high.
Extrusion is a procedure, which involves passing a
material of pasty consistency (it could either be a melt
or a solid/liquid blend) through orifices using a turning
screw. It then proceeds to be sliced, cooled and/or dried
and from this we obtain the granules.
Wet granulation is another known procedure, which
involves pulverizing a powdered solid with a moving liquid
to give granules that are later dried.
Other previous literature includes the German patent
DE-3446424A1 and US patent n° 5.560.122.
The patent DE-3446424A1 describes an IR radiation
application to dry solid materials, where IR emitters are
located inside a rotating drum with cooled walls, which
permits the drying of solids via a batch process. This
invention presents certain disadvantages, which are
resolved using this new technique. The new technique
described below presents the following comparative
It is applicable in both batch and continuous drying
processes, not just batch.
- The vessel walls do not become heated due to the fact
that the IR radiation is selectively applied to the
product. In the previous system, both the walls and the
product that sticks to the walls reach higher
temperatures than the main bulk of product to be dried.
This is because the walls are exposed directly to IR
radiation and may risk the product quality, as usually
happens due to excessive temperature.
The present invention has a system for breaking up the
lumps that are often formed, which the previous patent
does not possess.
The present invention avoids the surface deposits of
product inside the dryer, which can lead to the
deterioration of the product due to excessive and
prolonged heat exposure.
The dynamic of the movement of the dried bed minimizes
the creation of dust clouds, unlike the previously
mentioned patent, where the generated dust tends to
cover the IR radiation source. This may also lead to
The U.S. patent nr. 5.560.122 is also a batch process
apparatus, which is used for the blending, wet granulation
and post-drying of pharmaceutical products through four
different methods. The drying methods include contact, IR
radiation via an external window, the injection of hot air
and vacuum. This second invention also presents certain
disadvantages, which are resolved by the new technique.
The comparative advantages of the new technique are the
It is applicable in both batch and continuous drying
processes, not just in batch.
- Only one single source of energy (IR radiation) is
used, instead of four sources: contact, IR radiation
via an external window, the injection of hot air and
- Being direct the transmission of the IR, its efficiency
is much higher and it reaches a much wider surface
area, unlike the patent previously mentioned, where the
imposition of a glass window limits the surface
exposure. This window not only causes a loss of
radiation intensity but also requires the window to be
cooled due to the absorbed radiation by the glass and
the over-heated product that sticks to the inner side
of the window. This adhered product may deteriorate and
therefore it could contaminate the agglomerated
material if it comes loose..
The advantages of this new procedure when compared to
the current techniques, such as wet and dry compacting,
are that it does not require post-treatments like the
granulation (size reduction) of the compacted product
sheets, and neither drying. The particles obtained from
the new technique can be much smaller, with spheroid
shape, and less content of dust and more attrition
resistant, all of which makes the material more free-
Furthermore, other advantages should be taken into
account, such as the energetic savings that come from not
having to evaporate so much water and from the fact that
the volume of the required equipment is much less. With
respect to extrusion, where the products are fused, the
new technique offers significant advantages: critical
steps such as passing through the orifice and product
slicing can be avoided, the particle size is smaller, and
the particle spherical shape. These improvements are
basically in final application, storage and transportation
of the final product.
The energetic efficiency of the new procedure is not
significantly influenced by the shearing stress of the
extrusion screw. Thus, due to it operates with very minor
shear stress the deterioration of the product is very low.
The ease of processing products of low bulk density does
not reduce production. The presence of volatiles is not
problematic given that gases do not end up trapped inside
the barrel, as happens for example with extrusion. Thus
degasification is not necessary. Furthermore the
temperature, which must be reached by the product to
become granulated, is less. This not only increases
energetic efficiency but also causes less damage to
thermally unstable products. The new technique leads to
greater process control and far less energetic cost.
On the other hand the described technology presents a
notable advantage, compared to the wet granulation
process, when melted components are present, as they can
act as an agglomerating agent thereby rendering the later
steps of pulverization and drying unnecessary. In the case
of the liquid pulverization procedure, which is also
described herein, the system has the advantage of
combining both the wet granulation and the drying into the
The technical sectors to which the new invention is
directed include among others the chemical,
pharmaceutical, agrochemical, food, iron/steel, plastics,
ceramic, rubber, fertilizer, detergent, powder coatings,
pigment and waste treatment industries.
The objective of this invention is to improve the
material handling and flow of the product, avoid the risk
of lumps formation, facilitate the dosing, reduce the risk
of dust cloud explosions, prepare the product for direct
compression, reduce user exposure and any other associated
With the new method, several functions can be carried
out in just one unified unit, whereas up until now each of
these functions have required different machines. This can
be explained via three application fields, each titled by
way of example below:
- The first field is for products that need to be dried
with solvent recovery. The new technique allows for the
production of dry, powder or granular product with the
aforementioned machine; whereas conventionally one
would require various machines disposed in series: a
dryer with solvent recovery, a cooler of powder dried
product, an intermediary silo for the powder product,
and a sieve for fine-particle recovery.
- The second field is to obtain a granular product
comprised of several components in powder form with
total or partial product melting. The new technique
permits the production of granular material composed of
various powder components in one single equipment; this
considering that what is usually required is a mixing
and fusion machine (extruder) and a water-cooled heat
cutter positioned after it, followed by an air dryer to
remove the water and finally a sieve to separate the
fine particles from the coarse ones.
The third field deals with obtaining a granulated
product to be directly compressed into tablets,
starting from filter press cake. Using a single unit
the new technique allows for the production of granular
product, which is known in the pharmaceutical industry
as "Direct Compression" (DC) quality. Usually this
would require several machines in series, such as a
dryer with solvent recovery, a cooler of powder
product, a intermediary silo for the powder product, a
compactor, a granulator (particle size decrease) and a
The invention procedure is based on the application
of infrared radiation on moving powder form material with
the aim of producing particles of agglomerated material.
Depending on the material's composition, the absorption of
radiation produces different effects: if the blend
includes compounds with low melting points, a partial
fusion occurs; and if the mix includes volatile compounds,
the material is dried. In general, both phenomena may
occur. Each of the effects is used to create agglomerate
particles of a controlled size.
The material to be processed can be wet, as in the
case of the filter press cake, or dry with low or no
volatile substances content. The material may also be
composed of a single compound or several ones. In the case
of several compounds, the process simultaneously performs
a homogenous blend.
If the solvent medium is a liquid, this can be easily
recovered from the generated vapours by condensation,
first having the machine suitably sealed. If on the other
hand the products are dry, the agglomeration with the
aforementioned machine can follow two different routes:
The first involves the partial melting of some of the
starting material components, which will in turn act as an
- The second way is to spray the material with a liquid
which dissolves one or more components of the initial
material, or which contains components that act as
agglutinants themselves. If the liquid is volatile, it is
evaporated by a further application of IR radiation.
The procedure can also be adapted to either batch or
continuous processes. In both cases, the material flow
inside the equipment can follow a Plug-Flow reactor (PFR)
model or the Completely Stirred Tank Reactor (CSTR) model
or any intermediate material flow between these two ideal
The source of IR radiation should ideally be a
ceramic or metallic surface, which emits radiation via the
Plank effect with superficial temperatures that oscillate
between 200°C and 3000°C. The source of this radiation
energy is usually electric, although other alternatives
such as direct combustion of liquid or gaseous fuels may
be applied in those processes where said cheaper energy
sources are required.
Further details and features of the method and
machine for the agglomeration and/or drying of powder
materials using infrared radiation will be clearer from the
detailed description of preferred embodiments, which will
be given hereinbelow by way of non limitative examples,
with reference to the drawings herein accompanied, in
Figure n° 1 is a front elevated schematic view of the
machine according to the invention in a non-airtight
version, in which each of the different parts can be seen.
The machine is conceived for working in continuous with
pulverization provided with a crusher axis.
Figure n° 2 is an elevated cross-sectional schematic
view of the machine according to the invention in a non-
airtight version, to be operated in continuous form with
only two mixing shafts and without a crusher shaft.
Figure n° 3 is a front elevated schematic view of the
machine according to the invention in an airtight version,
in which each of the different parts can be seen. As such
it can operate in continuous form but without a crusher
There follows a detailed and numerated index to
define the different parts in the embodiments of the
invention as shown in the figures annexes: (2) set of
valves, (10) vessel, (11) shafts, (12) blades, (13)
focusing screen, (14) IR source, (15, 16) mixing elements,
(17) spray, (18) product, (19) screw, (20) granulator,
(22, 23, 24) sensors, (25) vent, (26) rotary valve, (28)
cover and (29) vacuum outtake.
The continuous operation mode is a preferred patent
Operation in continuous mode A:
The machine is continuously fed with the different
components of the formula to be dried and/or granulated
(18), this is done in such a way as to control their mass
input flow into the vessel (10) . The mass will be stirred
with a rotating shaft (11) with blades (12). It is
provided multiple stirring shafts (11), but al least two.
These two stirring shafts are designated in the drawings
as references (15) and (16).
A focusing screen (13) containing the IR source (14)
is located above the vessel (10) . The power of this
infrared radiation source (14) is regulated by measuring
the source temperature or, in case of direct combustion,
controlling the flows of fuel and air.
The stirring elements (15) and (16), which are
comprised of rotating shafts (11) with blades (12), ensure
a rapid renewal of the product exposed to the surface of
the vessel, which contributes to a higher homogeneity of
the drying and/or granulating process.
It exists two different type of stirring elements (15
and 16) , which revolution velocities can be regulated
The upper stirring element (15) rotates at a lower
velocity and its basic utility is to renew the product
located on the upper surface of the mass and mix it more
evenly with the product located further down in the mass.
The main purpose of the lower stirring element (16),
whose presence is optional, is to break up those lumps
that exceed a certain size using its greater rotating
The shafts of the stirring elements (15 and 16) can
be extracted in order to facilitate cleaning tasks and product changes. These shafts (11) are designed is such a
way as to allow blades (12) of varying their length,
width, thickness and inclination (of the angle with
respect to the rotating axis), in order to adapt to the
desired properties of the final product. These
characteristics determine the flow dynamics of the product
inside the machine.
These variations in the length, width, thickness and
inclination of the blades (12) are achieved by either
substituting them with other blades of a different
size/shape, or indeed by using blades specifically
designed to allow a certain degree of adjustment of the
The length and dimensions of the blades (12) allow a
self-cleaning effect, given that the blades (12) of one
shaft (11) intersect with the blades (12) of the adjacent
shafts (11). The tolerance (gap) between adjacent crossing
blades can be adjusted by means of changing and/or
modifying the blades (12). The potential deposits of
product on the outer surface of the shafts (11) are
removed continuously by the end point of the blades of the
adjacent shaft; see figure n° 2.
The blades (12) are usually inclined with respect to
the advance of the rotation direction so that they also
produce an auto-clean effect. The inclination of the blade
(12), with respect to the turning shaft (11) for a given
direction of turn, controls the axial direction in which
the product advances. This circumstance is used to
regulate how the product advances and can also be used to
improve the axial mixing of the product by combining
different advance/hold back properties of adjacent blades
(12) of the same shaft (11), enhancing thus the mixing
effect in axial direction. In this way a homogenous
distribution of the product can be achieved in surface,
both laterally and axially; said homogeneity is
recommendable when opting for a batch process. The two
shafts (11) should preferably rotate in opposite
directions to maximize the blending.
In order to avoid deposits of the product on the
inner surface and/or dead zones, the tolerance (space)
between the outer points of the blades (12) and the inner
surface of the vessel (10) is minimum. This space can be
regulated by means of changing the length of the blade
(12). The maximum length value is based on the criteria of
approaching the gap size to the desired average particle
size. If this value is lower than the standard mechanical
design permits, the value will adjust to the one that is
recommended in this design.
If the addition of a liquid via a spray (17) is
chosen, the flow is adjustable according to the quantities
required. This function can be applied before, during or
after the IR radiation. The pulverization may be air-
assisted and should operate preferably with droplets of
low average size (1-200 microns). The quantity of liquid
added can vary between 3 and 40% of the weight of the
final granulated/dried product.
The agglutinating material can be either a liquid or
a melted solid. The liquid can contain dissolved solids,
dispersed solids or other dispersed non-miscible liquids.
The continuous extraction of the final product is
achieved by overflow when it exceeds the level at the
discharge point (9) , which is located as far as possible
from the feeding point. The height of said discharge level
is adjustable. In the case of heavy lumping, the product
may be forcibly extracted via a screw (19) with adjustable
Once the product is discharged, the maximum particle
size of the product can be guaranteed by installing a
granulator (20) , which continuously will crumble the
coarse particles: it will force the product through a
metal mesh whose aperture size equals the maximum desired
The granulator (20) installation is optional, given
that in most applications the quality of the granule
obtained from the machine regarding the particle size is
If the final product has not to contain particles
below a certain size (fines) , a sieve (not included in
figures) may be placed afterwards, and the fines recovered
here can be continuously recycled back into the feed of
The product usually requires cooling before it is
packaged and room-temperature air is preferably applied
while the product is being transported by vibration, by
screw or by fluidised bed. The cooling phase can be
carried out immediately after discharge and/or before the
granulation/sieving step, depending on the nature of the
Both the vessel (10) and the screen (13) are
externally covered with thermal insulation material to
minimize energy loss and also to avoid the accidental
burning of the personnel who are running the machine.
The focusing screen (13) is designed to have an
adjustable height in relation to the upper surface of the
vessel (10). This allows one to vary the distance between
the emitting elements and the product surface between 3
cm. minimum and 40 cm. maximum.
To achieve good final product uniformity, it is
important that local overheating above working temperature
does not occur in any part of the vessel (10) . This is
obtained thanks to a combination of the following
a) The internal surface of the vessel (10) is highly
reflective to IR radiation and has a metal mirror-
finish. The coating includes aluminium, nickel, silver,
zinc, etc. This finish also reduces the adherence of
product and facilitates cleaning.
b) The area irradiated does not cover the entire upper
surface of the product exposed to the air, so the
incidental radiation that comes from the source is
practically negligible in strip form area surrounding
the internal perimeter of the vessel, see figure n° 2.
c) The use of thin disposable reflective sheets of metal
(8) placed at the edge of the focusing screen (13) to
minimize the radiation likely to reach the wall of the
vessel (10), see figure n° 2.
d) Refrigeration of the fraction of the vessel wall (7)
directly exposed to radiation, see figure n° 2.
The use of one or more of these elements will depend
on the inherent requirements of the desired product.
The correct parameters to achieve a suitable
granulation and/or drying are determined by previous
testing, which allow defining the operating temperature,
the intensity of radiation, the flow of product and the
stir velocities required to achieve a desired product
(particle size distribution, volatile content, etc.).
There are various sensors (22, 23 and 24) located
inside the vessel (10). They are submerged in the product
and measure its temperature, which allows controlling the
process during start up and during continuous stationary
state. At the same time, they give a good indication of
the flow's condition of the product along the length and
width of the vessel (10).
The described process also applies when the
production requires a controlled atmosphere. This
controlled atmosphere can be in terms of pressure that
are above or below atmospheric, or can be in terms of
composition (N2, C02, etc.). In both cases the
granulating/drying machine must be sealed as described.
The composition of the atmosphere that surrounds the
product can be controlled adjusting the inert gas flow
(25), see figure n° 3.
For continuous processes airtight or semi-airtight
elements are necessary, which can allow the continuous or
semi-continuous feeding and continuous extraction of the
material. For this purpose 8-blades rotary valves (26) or
systems of two valves with an intermediate chamber where
one of the two valves (2) is always closed are employed.
The vacuum outtake and and/or outlet for volatile
vapours are installed in the cover (28) for (29).
With regards to the airtight sealing of the IR source
and the vessel, a cover (28) is used, which covers the
perimeters of both these elements with an elastic seal.
If the pressure inside is below atmospheric, there is no
need for any additional attachments, as the vacuum effect
itself will maintain the seal of the elements. If
pressure above atmospheric is required, it is essential
to attach pressure screws to ensure that the cover and
vessel remain joined together. The shafts (11) have
suitable tight sealing with gasket or packing glands.
In the case where solvent recovery is required, the
equipment will be sealed and the generated vapours
recovered via condensation by a cooling unit placed
between the cover and the vacuum generator. In the case
of operating without vacuum, the vapours will be
condensed before being released into the atmosphere.
Operation in batch mode B:
The operation mode of this system differs from the
previous continuous system A in that the quantities of
different solid components to be granulated/dried are
added to the vessel (10) at the beginning of the process.
They are then mixed.
If drying is all that is required, one simply
connects the IR source.
If granulation is required via the addition of a
liquid spray, this is done at the beginning, gradually
adding the required quantity.
Once the mass has been homogenously mixed and/or
fully agglomerated into granules, the drying, if
required, begin by connecting the IR source.
If the agglomeration occurs through a melted
component, the IR can be applied during the mixing
Once the product had been granulated and/or dried,
which you can judge by its physical aspect and by the
temperature reached, it is discharged. The batch machine
has a discharge door in its lower part so that it can be
Both the revolutions of the shafts (11) and the power
emitted by the focusing screen (13) can be adjusted
throughout the batch process to improve the homogeneity
of the mix, to reduce the formation of dust clouds and to
increase the efficiency and consistency of the process.
The shape and size of the batch machine can differ
substantially from the images shown in figures n° 1, 2,
and 3. This is because the required capacity of the
machine tends to be greater in order to produce large
batches. In the batch process the quantity of product per
unit of irradiated surface would be much higher than in a
continuous process. The design of the stirring elements
and placing of a door is such as to permit the complete
emptying of the product once the batch process is
The sealing elements for a batch machine are much
simpler, as they only have to isolate the vessel and IR
source from the surroundings.
Once this invention having been sufficiently
described in accordance with the enclosed drawings, it
will be understood that any detail modification can be
introduced to the machine as appropriate, unless
variations may alter the essence of the invention as
summarized in the appended claims.
1. A process for the agglomeration of materials originally in the form of dry powder or wet cake to obtain solid granules, through the use of infrared radiation, characterized in that the process comprises the following steps:
continuous feeding of the component materials to a vessel (10);
stirring with at least two counter-stirring shafts (11) from respective stirring elements (15, 16) with respective attached blades (12), the shafts being designed to allow blades of varying their length, width, thickness and inclination (of the angle with respect to the rotating axis), the length and dimensions of the blades allowing a self-cleaning effect and avoid deposits of the product on the inner surface and/or dead zones and allow a Plug-Flow reactor (PFR) model or the Completely Stirred Tank Reactor (CSTR) model given that the blades of one shaft (11) intersect with the blades of the adjacent shafts, and also allow a homogenous blend and allow the shafts of the stirring elements (15 and 16) to be extracted; eventual addition of liquid agglutinating material via pulverization;
application of IR radiation on a surface which is continually supplied with renewed powder by a infrared source (14) located inside a focusing screen (13), thin disposable reflective sheets of metal (8) being placed at the edge of the focusing screen (13) to minimize the radiation likely to reach the wall of the vessel (10), the area irradiated does not cover the entire upper surface of the product exposed to the air, so the incidental radiation that comes from the source is practically negligible in strip form area surrounding the internal perimeter of the vessel, both the vessel and the screen are externally covered with thermal insulation material to minimise energy loss;
extraction of volatiles vapours by IR source, and in the case where solvent recovery is required the generated vapours are recovered via condensation by a cooling unit; - continuous discharge of the agglomerated product by overflow discharge system with an adjustable height (9) at the opposite end of the vessel (10) to the
2. The process as claimed in claim 1, wherein the source of this radiation energy is
usually electric, but other alternatives such as direct combustion of liquid or gaseous
fuels may be applied in those processes where said cheaper energy sources are
3. The process as claimed in claim 1, wherein it can be applied for the drying wet
bulk materials to obtain dried powdered and/or agglomerated material.
4. An apparatus for carrying out the process as claimed in claims 1, 2 or 3, said
- a vessel (10) externally covered by an insulating material and which is fed of
product(18), the internal surface of the vessel (10) being highly reflective to IR
radiation by employing metals as aluminium, nickel, silver, zinc and having a mirror
- sensors (22, 23 and 24) for temperature control being located inside the vessel
(10) and submerged in the product that measure its temperature;
- at least two counter-stirring elements (15,16) with respective extractable shafts
(11) in the interior of the vessel (10) are positioned horizontally with attached blades
(12), said counter-stirring shafts (11) ensuring a rapid renewal of product exposed to
the surface, the blades (12) having the possibility of varying the length, width, and
thickness and inclination (angle with respect to the shaft), this inclination of the blades
(12) with respect to the aforementioned shafts(11) allows the control of the progress
flow of the product inside the vessel and the homogenisation degree of the product, in
lateral and axial directions, and in composition and particle size, thus the tolerance
(gap) between adjacent crossing blades can be adjusted by means of changing and/or
modifying the blades (12), and the end point of the blades of the adjacent shaft being
adapted to removed continuously the potential deposits of product on the outer surface
of the shafts (11);
- a focusing screen (13) in the upper part of the machine is positioned
horizontally, said focusing screen (13) externally covered with insulation material and
thin disposable reflective sheets of metal (8);
- a source of infrared radiation (14) in the interior of the focusing screen (13),
being the infrared source (14) a hot ceramic or metallic surface at temperature between
200°C. minimum and 3000 °C. maximum that is heated by electric energy supply or by
direct combustion of gaseous or liquid fuels;
- a cover (28) which covers the perimeters of the IR source and the vessel with
an elastic seal.
5. An apparatus as claimed in claim 4, wherein there are provided two types of
stirring elements (15 and 16) having revolution velocities that can be regulated
independently, upper stirring element (15) rotates at lower speed than lower stirring
element (16), lower stirring element (16) breaks up those agglomerates that exceed a
6. An apparatus as claimed in claim 4 or 5, having additional elements for working
as continuous airtight processes allowing a continuous or semi-continuous feeding and
continuous extraction of the material, the machine being provided with 8-blades rotary valves (26) or with a set of two valves with an intermediate chamber where one of the
two valves (2) is always closed, the shafts (11) having a suitable tight sealing with
gasket or packing glands, thus airtight conditions allows to work in a pressure below
or above atmospheric one, and to work in a controlled atmosphere composition adding
an inert gas flow (25).
7. An apparatus as claimed in claims 4, 5, 6 or 7, wherein a vacuum outtake (29) is
installed in the cover (28), and afterwards a cooling unit where the vapour is
condensate and original liquid content is recovered.
A PROCESS FOR THE AGGLOMERATION OF MATERIALS THROUGH THE USE OF INFRARED RADIATIONAND AND APPARATUS THEREOF
The invention relates to a process and an apparatus, as well as the variants thereof, which operates continuously or discontinuously for the agglomeration and/or drying of powder materials using selective infrared irradiation on a surface which is continually supplied with renewed powder by a infrared source (14), with eventual addition of liquid agglutinating material via pulverization (17). The process can be performed in sealed conditions or open the atmosphere, with or without the recovery of volatile components.
|Indian Patent Application Number||966/KOLNP/2007|
|PG Journal Number||18/2013|
|Date of Filing||19-Mar-2007|
|Name of Patentee||IGLESIAS VIVES, JOAN|
|Applicant Address||POL.IND.CAN MAGRE,C/JOAN GUELL, ESQUINA NARCIS MONTURIOL, E-08187, SANTA EULALIA DE RONCANA|
|PCT International Classification Number||F26B 3/30|
|PCT International Application Number||PCT/ES2004/000412|
|PCT International Filing date||2004-09-21|