A compacting granulator for continuous, compacting granulation comprises a substantially horizontal rotatable drum, through which an eccentric shaft extends, which carries compacting means which partly transfer substantial amounts of energy to the granulate possible for attainment of a high degree of compacting, partly hurl up the material under treatment, so that the material, while hurled up, is brought in intimate contact with a treatment liquid sprayed through the nozzle. A stationary scraper as well as nozzles with individual feed supply ensures great flexibility and a reliable operation.

BACKGROUND OF THE INVENTION 
The invention relates to a compacting granulator for continuous, compacting 
granulation and possible simultaneous mixing of at least one powdery or 
pasty material under supply of at least one fluid in a drum. 
In many industries producing or handling powdery materials a granulating or 
agglomerating treatment is performed for making the materials less dusty, 
to increase their flowability, to make them easier to dose or in general 
easier to handle or to give them a desired appearance, by which treatment 
the primary particles and/or small agglomerate granules are united for the 
formation of bigger agglomerate granules. It may also be of interest to 
produce granulate on the basis of pasty starting materials, possibly with 
the addition of dry, powdery components. 
Examples of such industrial branches, in which such processes take place, 
are the detergent industry, the fertilizer industry and the food, drink 
and tobacco industry as well as the pharmaceuticals industry and the 
metallurgical industry. 
The attainment of agglomerated particles is achieved by use of widely 
differing measures either as part of a drying or production process or as 
a pre-treatment and by use of binding forces which are either present 
spontaneously or provided by the supply of suitable liquid or vaporous 
auxiliary means. 
Many agglomeration processes, as for instance those performed in connection 
with a spray drying or a subsequent treatment in a fluidized bed, however, 
entail a reduction of the powder density of the material, also called the 
bulk weight, which in respect of a lot of products is undesirable, i.e. on 
account of increased packing and transport costs. To this may be added 
that the consumers wishes for instance within the detergent area tend to 
go towards more concentrated products, for the production of which 
components with relatively high powder density are used. 
It is known that in connection with the selection of detergent components 
in a particular ratio, by mechanical treatment of the powdery material 
derived from spray drying by addition of a tenside acting as a binding 
agent, a detergent agglomerate with increased powder density is obtained, 
presumably because the mechanical treatment results in dense agglomerates 
with comparatively little interspace air between the primary particles. 
Such a treatment is disclosed in published Danish Patent Application No. 
1823/89, in which it is proposed to perform the agglomeration or the 
granulation while the material passes through a horizontal or slightly 
tilting mixing drum, in the interior of which a central, rotatable shaft 
is provided, the shaft carrying several radially directed impact tools. 
The mixing drum itself is stationary, and the passage of the material 
through the drum is therefore exclusively controlled by the impact tools. 
Related apparatuses are known which have a horizontal, rotating mixing 
drum, in which a stirring shaft, which is parallel to the axis of the 
cylinder, but positioned under and at the side thereof, rotates in the 
same direction as the drum, see Japanese Patent Application 79-23438 
(publication no. 80-116690). The described apparatus is for use in the 
manufacture of phosphate fertilizer with a surface layer of water-soluble 
phosphoric acid, the most important task being to distribute the liquid 
phosphoric acid on the phosphate granules. Inter alia as a consequence of 
the fact that the mixing shaft is adapted to rotate fairly slowly and that 
the design of the apparatus does not make an effective control possible of 
the staying time of the material in the apparatus and consequently the 
particle size, it will be obvious that this known apparatus is not suited 
for a real compacting granulation for the attainment of dense agglomerate 
particles with high density. Furthermore, the apparatus is not suited for 
treating material which consists of so small particles, that it is not 
flowing freely. 
In addition to this many mixing apparatuses are known, in which large shear 
forces are exerted on the material to be mixed (high shear mixers) and 
which are provided with a fast rotating impeller, which apparatuses may 
also be used for agglomeration, for instance in connection with the 
spraying of a suitable liquid. However, it is here substantially the 
question of apparatuses working batchwise and which are less suited for 
industrial production on a large scale. 
Within the detergent industry the apparatuses used for agglomeration and 
compacting comprise i.a. an apparatus which combines a mixing in a 
V-shaped chamber with the impact from an impeller. The compacting ability 
of these apparatuses does not, however, reach the desired level. 
A granulator is required which combines the following properties or 
characteristics: 
1. Continuous operation 
2. The possibility of obtaining more compact agglomerates than can be 
obtained with known apparatuses with a single passage of the material to 
be treated 
3. Big production capacity 
4. The possibility of obtaining a narrow granule size distribution, and 
5. General applicability for treatment of very differing materials without 
operational complications. 
It has turned out that the possibility of meeting the requirements 2 and 4, 
i.e. the attainment of particularly compact agglomerates with narrow 
granule size distribution, does not solely have as a prerequisite that the 
mechanical conditions are present, in this respect the sufficient working 
energy, to obtain an effective compacting, but also to a very high extent 
the prerequisite of imparting to the material being treated a particularly 
homogenous moistening or contact with the agglomeration fluid used in the 
process. 
In the known apparatuses of the type comprising a drum, the granulation 
fluid is introduced in form of a liquid or vapour, the latter being 
condensed on the powdery material, by means of nozzles which are either 
placed where the very powder mass is present during the operation of the 
apparatus or placed above the powder and adapted to distribute fluid on 
the surface formed by the powdery layer during its tumbling in the drum. 
Since the speed of the turning over of the powder is limited, the 
distribution of the liquid sprayed on or condensed becomes insufficient in 
the powder mass, the particles close to the surface of the powder layer 
being strongly moistened, whereas the particles positioned deeper in the 
powdery layer will have to participate in the tumbling process caused by 
the rotation of the drum for a long time before ending in the surface 
layer, where the moistening takes place. Thus, there are in the known 
apparatuses far from optimum conditions in respect of obtaining a 
homogenous moistening. 
A more homogenous contact between the material in the drum and the 
agglomeration fluid blown in is achieved when this contact takes place 
while the material is projected in the air space in the drum, such that 
the powdery particles do not touch each other at the time of contact. As 
in the case in the known agglomeration processes in a fluidized bed, a 
considerably more homogenous moistening is obtained than would be the case 
if it took place while the particles were in mutual contact. When a 
particle projected in the air contacts a drop of liquid, the drop is 
evenly distributed on the surface of the particle. If, however, a drop of 
liquid hits a material which is in such a condition that the particles are 
in contact, the liquid will first and foremost penetrate into the 
interspaces between the particles and cause a very random and 
inhomogeneous conglomeration thereof. 
This perception is used in the granulator according to the invention which 
better than any known apparatus is capable of meeting the combination of 
requirements listed above under 1-5. This granulator is according to the 
invention characteristic in comprising 
SUMMARY OF INVENTION 
i) a drum rotatable around a substantially horizontal longitudinal axis, 
said drum having a length which is bigger than its diameter, and means for 
introducing pasty or powdery material at one end and means for removing 
granulate at the opposite end, 
(ii) a shaft extending parallel with the longitudinal axis of the drum 
through the length of the drum placed eccentrically in the drum in a level 
below the longitudinal axis of the drum and displaced laterally in the 
rotational direction of the bottom part of the drum relative to the 
vertical plane through the longitudinal axis, said shaft being at at least 
the major part of its length present in the drum provided with compacting 
means, the parts of which that are farthest away from the shaft passing, 
when the shaft is rotating, through an area near the part of the drum wall 
which is closest to the shaft, 
iv) means for rotating the drum around its longitudinal axis as well as 
means for rotating said shaft in the same direction and with a number of 
revolutions, which may be adjusted to a value which during the running of 
the granulator is from 10 to 1000 times bigger than the number of 
revolutions of the drum for hurling up the tumbled material present in the 
drum such that it is thrown through a path outside the area, where the 
product would be present in the drum, was it not influenced by the 
compacting means, 
iv) at least one scraper arranged stationarily in the drum for removing 
material from the inner wall of the drum for uniting it with material 
uphurled by the compacting means and 
v) at least one nozzle for distributing at least one fluid in the part of 
the drum which is passed by the material in uphurled state. 
BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Preferred embodiments and details of the granulator according to the 
invention are specified in the subclaims and explained in detail in the 
following with reference to the drawing, in which

The embodiment shown in the drawing of the granulator according to the 
invention comprises a circle-cylindrical drum 1 which is carried and 
controlled by rollers 2. 
In the embodiment shown the drum is horizontal, but it may alternatively be 
supported having a slight inclination in the direction which in FIG. 1 is 
to the right, to further the passage through the drum of the material to 
be treated. A slight inclination in the opposite direction may be used for 
the attainment of a certain control of the filling degree of the drum, but 
this is, however, preferably ensured by other means which will be 
described below. 
As will most distinctly be seen from FIG. 2 the drum is in the embodiment 
shown provided with a gear rim 3, and it is made to rotate by means of a 
toothed wheel 4 engaging the gear rim, said wheel being driven by an 
electromotor 5. The motor will typically be adapted during operation to 
give the drum a peripheral speed of 25-200 m/min, preferably approx. 50 
m/min. 
At one end of the drum inlet means 6 are provided for introducing pasty or 
powdery material, whereas the other end is provided with means for 
recovering of granulate, said means comprising an overflow edge 7, the 
level of which may be adjusted by displacement of shielding plates 8, and 
a lower slide gate 9 for removal of big granules and lumps as well as for 
the emptying of the drum. 
The material introduced through 6 does not have to be in a dry, free 
flowing condition, but may be moist and for instance introduced in form of 
a filter cake, which will disintegrate in the drum. When the material is 
introduced as a paste, for instance metal oxides for use as pigment or as 
a component of technical ceramics, a dry, powdery material may be 
introduced simultaneously, the need for drying and consequently the energy 
consumption of the process as a whole being thereby reduced. 
Through the drum 1 a shaft 10 extends parallel with the axis of the drum 
but eccentrically relative thereto, the shaft being supported at each end 
in bearings 11. The shaft 10 is positioned lower than the longitudinal 
axis of the drum and displaced laterally relative thereto, its position 
being in the zone, where the material will gather under influence from the 
rotation of the drum. 
The shaft 10 is at substantially the whole length of the shaft which is 
present in the drum provided with compacting means 12, in the embodiment 
shown in form of arms, which by quick rotation of the shaft 10 exert a 
compacting, density increasing effect on the agglomerates present in the 
drum or being created therein. This compacting effect is of paramount 
importance since the necessary mixing and partly the agglomerating effect 
are obtained by the relatively slow rotation of the drum 1. 
The shaft 10 is driven by an electromotor 13, which, as indicated by the 
dimensions used in FIG. 1, has a considerable strength and substantially 
bigger operating performance than the electromotor 5 running the drum 1. 
For obtaining the desired compacting effect it is vital that the compacting 
means 12 have a surface substantially perpendicular to their travelling 
direction, and they may typically be designed as arms, which for the 
attainment of the necessary strength are designed with rectangular 
cross-section, the longest dimension of this being in the rotational 
direction. 
In addition to the compacting effect on the material in the drum the 
compacting means 12 have the important function to bring about the 
projecting of the material particles, as outlined in FIG. 4, which is 
vital for the desired result and which will be explained in detail below. 
In the drawing it is indicated that the shaft 10 is hollow, and it may at 
its end opposite the electromotor 13 be connected with means (not shown) 
for supply of one or more fluids. 
From the hollow interior of the shaft this fluid may through openings or 
apertures 20, preferably in form of pressure nozzles, be led out into the 
drum for moistening of the particulate material present therein. The 
hollow shaft is in particular used for introducing cleaning liquid for 
cleaning the apparatus between periods of running. By using spreading 
nozzles a most effective rinsing is ensured. 
In the upper part of the drum at least one scraper 14 is placed 
stationarily at a very small distance from the inner wall of the drum for 
removal of material therefrom. 
In the embodiment shown the scraper carries a number of nozzles 15, which 
may be pressure nozzles or preferably two-fluid nozzles. The nozzles 15 
are individually or group-wise connected to supply tubes 16 making the 
supply of fluid separately to individual nozzles or groups thereof 
possible. The supply tubes 16 are preferably surrounded by a heating 
jacket 21, which makes it possible to supply liquids which would solidify 
or become too viscous at ambient temperature. 
Decisive for the attainment of the object of the invention is the 
positioning of the nozzles 15 in such a way that they deliver their fluid 
to the area of the drum, in which the treated material is present as 
particles, which are thrown up into the air without being mutually in 
contact. 
Even though there is a possibility of using vapour or steam as 
agglomeration fluid, it is much more frequent, however, to use a liquid 
for that purpose, for which reason the following description is based on 
the assumption that the fluid is a liquid. 
The preferred nozzle arrangement makes it possible to use sequential 
spraying, possibly of mutually incompatible liquids, such as aqueous 
solutions of hydrophillic compounds and solutions of hydrophobic compounds 
in organic solvents. 
In the embodiment shown the portion of the drum, which is shown to the 
right in FIG. 1, ends in a housing 17, which is shown partially cut away 
in FIG. 3. In the top of this housing an exhaust branch 18 is provided, 
through which by means of structure not shown a certain air exhaustion 
takes place during the operation of the apparatus. Hereby is achieved that 
a somewhat reduced pressure may be maintained, and this has the effect 
that dust in the connection between the drum and the housing 17 as well as 
between the drum and a cover 19 present in the opposite end is prevented, 
an inwardly directed air flow on these places preventing dust from the 
drum from reaching the gaskets (not shown). 
Furthermore, the exhaustion through 18 results in an air flow in the drum 
which may be utilized for obtaining a cooling effect therein for partial 
removal of the thermal energy released by compacting. 
As a supplement to or as an alternative to an exhaust as described a 
blowing in of compressed air may be used at the connection between the 
drum and the cover 19 or the housing 17 for preventing dust or particles 
from reaching the packaging means. 
In a typical application of the granulator it is used for the production of 
a substantially dust-free detergent consisting of granules with desired 
size distribution and with considerable density, said detergent therefore 
having a big powder density. In a single passage of material a powder 
density for detergents of usual composition of more than 1.0 g/ml is 
obtained. 
The starting material may for the major part be a spray-dried powder 
comprising most of the components being part of the end product, in 
particular components that are insoluble in water or other relevant 
solvents. 
As a consequence of the intensive mixing which also takes place in the 
granulator according to the invention, it is not necessary for the 
detergent production that the starting material is unified in advance by 
spray-drying or the like, but the individual components may be added 
separately or as a coarse mechanical mixture. 
The apparatus may also be used as a compacting, agglomerating reactor, for 
instance in connection with the dry-neutralizing process used in the 
detergent industry, in which case sulphonic acid is sprayed through one or 
more nozzles on soda which is tumbled and tossed in the drum. 
By using the granulator according to the invention the drum 1 is brought to 
rotate with the rotational direction shown in FIG. 4, following which 
introduction of the starting material into the drum is initiated through 
the inlet 6. 
Were the shaft 10 with the compacting means 12 not present in the 
apparatus, the powdery starting material would place itself in the drum as 
indicated by the hatching in FIG. 2 and by the dotted line in FIG. 4. 
Whereas the rotational speed of the drum as mentioned typically corresponds 
to a peripheral speed of approx. 50 m/min, the shaft 10 is brought to 
rotate by means of the strong electromotor 13 with a speed corresponding 
to a peripheral speed for the compacting means 12 of between 500 and 2000 
m/min, which in addition to the compacting effect on the powder has the 
effect of throwing it in a steady flow up in the portion of the drum which 
on FIGS. 2 and 4 is shown on top to the right. This throwing is so 
comprehensive that the particles constantly flow like a carpet through the 
area in question, as indicated in FIG. 4. 
While the particles are thus thrown through the air, they are exposed to 
the fluid sprayed in through the nozzles 15, and a more homogenous 
distribution of the fluid on the particles is obtained than would be the 
case if the contact between fluid and particles had been established while 
the particles were in mutual contact in the bottom portions of the drum. 
Simultaneously with the compacting means 12 causing the in view of an even 
moistening most advantageous throwing up of the powdery material, said 
means exert a strong mechanical working, the agglomerates formed as a 
result of the moistening obtaining a high density with accompanying high 
mechanical strength and specific weight. 
It should be observed that the flow pattern decisive for the attainment of 
the desired results is conditioned by the combination of the tumbling 
effect caused by the rotation of the drum and the projecting and 
compacting effect, which is exerted by the compacting means 12 mounted on 
the shaft 10. 
When the moistened powder is exposed to the compacting effect exerted by 
the means 12 in co-operation with the inner surface of the drum 2, it will 
tend to adhere so strongly to the inner drum surface that it will not 
leave the drum merely by the influence of gravitational force during the 
rotation of the drum. It is therefore of importance that the scraper 14 
ensures that the material is liberated from the drum and falls down for 
subsequently being thrown up for renewed moistening and subsequent 
compacting. Advantageously the scraper is for that reason placed above the 
shaft 10, the material liberated by the scraper falling directly down into 
the area passed by the compacting means. 
When producing detergents and also many other products, it will be 
advantageous as liquid for introduction into the drum through the nozzles 
15 to use a solution of a component desired in the end product, or an oily 
component which is capable of acting as a binding agent between the 
particles moistened by the solution. 
Many materials and mixtures of materials will, however, have the inherent 
property that when just moistened with pure water or any other solvent 
they acquire such a tackiness that satisfactory agglomeration and 
subsequent compacting results are obtained. 
In apparatuses of the type in question there is a risk that for instance an 
overdose of the supplied liquid results in sudden formation of big lumps 
which will strongly impede the operation and necessitate a time consuming 
disassembling and cleaning of the apparatus. 
This risk is considerably reduced with the apparatus according to the 
invention due to the fact that the scraper 14 constantly removes any tacky 
deposits, which may appear on the interior wall of the drum, and causes 
them to fall down in an area, where they are influenced by the compacting 
means 12, which effectively will disintegrate such scraped off deposits. 
With a view to the flowability of the products, their freedom for dust or 
suitability for pelleting, it may be desirable to provide the compacted 
granulate particles with a coating. This will by use of the apparatus be 
feasible in the compacting step, a solution suitable for producing the 
coating being directed to those of the nozzles 15 that are closest to the 
outlet opening, whereby a special coating pre-treatment is made 
superfluous. 
As liquid supplied for the provision of or the supporting of the 
agglomeration and the subsequent compacting, liquids without solvent may 
be used in addition to the above-mentioned, i.e. either substances which 
are oily at normal temperature, or melted substances, the presence of 
which is desired or acceptable in the end product. 
If the liquid comprises or consists of a solvent, including water, which is 
not bound by chemical reaction or crystallization processes, and the 
presence of which is undesirable in the end product, the treatment in the 
granulator according to the invention will normally be followed by a 
drying, typically in a fluidized bed. 
Before removing the product obtained as compacted granulate from the drum, 
it may be advantageous to make a powdering (dust coating) thereof. For 
that purpose the coating powder may be introduced into the outlet end of 
the drum by means not shown, such as a worm or a pneumatic dosing system, 
which is passed through the stationary housing 17. This powder coating may 
take place in a substantial part of the length of the drum, for instance 
up to 75% thereof. 
The removal of the compacted material from the drum takes place from the 
overflow edge 7, the effective height of which may be changed by 
displacement of the shielding plates 8. Thus it also becomes possible to 
regulate material level in the drum and consequently the average residence 
time of the material therein, which may be essential for the attainment of 
a desired granule size. 
The granulate which passes the overflow edge 7 falls down into the bottom 
of the housing 17, from where it is removed for a possible 
after-treatment, like for instance said drying, or for direct packaging or 
for storage in a silo.