Title of Invention

A METHOD FOR GRANULATION OF CONCENTRATED SOLUTIONS

Abstract

The invention relates to a method for granulation of concentrated solutions by using a granulator (1) with several impact blades (3) arranged on at least two shafts (11) set in the desired feeding direction, whereby the shafts (11) rotate in a trough (2), with an inlet (4) at the beginning of the trough (2) for the material to be treated and an outlet (5) at the end of the trough (2) for removing the produced granulate, as well as entry nozzles (6,8) for entry of fluid into the trough (2). The material to be treated is mechanically fluidized by rotating impact blades (3); whereby a fused version of the product to be granulated is sprayed-on over the length of the treatment trough (2) through the feed nozzles (6) to the generated particles-bed, the fused material is fed to the particle bed through the spraying nozzles (6) as droplet mist; and the fused material is sprayed-on through the spraying nozzles (6) mainly vertically downwards between circular paths of the impact blades (3) directly on to the particles-bed.

Full Text

FIELD OF INVENTION The invention pertains to a method for granulation of concentrated solutions, especially for fertilizer production, by using a granulator with several impact blades arranged on at least one shaft set in the desired feed direction, whereby the shaft rotates in a trough, with an inlet at the beginning of the trough for the material to be treated and an outlet at the end of the trough for removing the produced granulate, as well as with entry nozzles for feeding of fluid into the trough. BACKGROUND OF INVENTION Such a method is known, for example, from the document US-3 825 414, whereby design details of the trough mixers used here are known from the Japanese abstract JP 9-277 244, in which twin shafts rotate with impact blades. Also in "Ullmai^n's Encyclopedia of Industrial Chemistry". 5th edition, vol. A 10, pages 376 ff, such impact mills or trough mixers are known. In such devices, a fused material is introduced from one side of the trough and mixed in the interior, whereby through the movement and by addition of fluid, the particles adhere to one another or get baked together. Granulation should be understood in this context as an enlargement of particles. US 3825415 describes a Pugmill granulation process for the production of fertilizers containing urea and ammonium polyphosphate. Concentrated urea solution is sprayed onto recycled solids in the pugmill followed by molten ammonium polyphosphate. The melt is fed to the pugmill at a minimum of 12 inches downstream from the urea to prevent hydrolysis of the urea which results in foaming and gas evolution. The product from the pugmill is essentially anhydrous, and no further drying is required. Other fertilizer materials such as ammonium sulfate, potassium chloride, or micronutrient sources may be incorporated by adding them to the pugmill during granulation. GB 599384 discloses a method and apparatus for preparing in a gaseous medium pulverulent non-coalescent dispersions. A pulverulent non-coalescent dispersion is prepared by producing in a gaseous medium a sheet-like zone in vortex movement into which particles of solid and particles of plastic are projected and become attached to each other by impact. Finely divided pulverulent material such as silica dust is fed into a chamber, and is propelled in a vortex of air created around each of two oppositely rotating impellers, comprising shafts and propellers. A fusible plastic such as residual asphalt is projected into the vortices under pressure from nozzles connected to a feed pipe 65. Guiding vanes may be provided to assist the movement of the air from one impeller to the other, or, alternatively, the end propellers may be so shaped that the movement of the air leaving these propellers has no axial component. The shafts may be hollow for receiving a heating or cooling fluid, which may also be supplied to pockets in the walls of the vessel. By controlling the temperature during the mixing either the solid or the plastic may form the exterior phase of the resultant particles. The batch is discharged through tilting doors. The pulverulent or comminuted solid may comprise a mixture of materials which may be combined in a dispersion with a common plastic. OBJECT OF INVENTION It is the task of the invention to achieve reproduceable granulates with optimum grain size with a high degree of effectiveness. SUMMARY OF INVENTION Accordingly, there is provided a method for granulation of concentrated solutions by using a granulator with several impact blades arranged on at least two shafts set in the desired feeding direction, whereby the shafts rotate in a trough , with an inlet at the beginning of the trough for the material to be treated and an outlet at the end of the trough for removing the produced granulate, as well as entry nozzles for entry of fluid into the trough. The material to be treated is mechanically fluidized by rotating impact blades, whereby a fused version of the product to be granulated is sprayed-on over the length of the treatment trough through the feed nozzles to the generated particles-bed, the fused material is fed to the particle bed through the spraying nozzles as droplet mist, and the fused material is sprayed-on through the spraying nozzles mainly vertically downwards between circular paths of the impact blades directly on to the particles-bed. In this method it is achieved, that the impact blades of the granulator are used for generating a fluidized particles-bed in a mechanical manner, whereby the material transportation in axial direction right through the granulator is ensured at the same time. By distributing the feed nozzles over the length of the trough, fluid can be fed in a very specific manner, whereby in this case a fusion of the product is fed in a special way. In this way, it is possible to continuously enlarge the initial small particles and build them up into granulates, which will have the desired size for extraction. The particles collide in the moving bed, whereby with the help of the sprayed-in fluid they get enlarged, adhere to one another or get mixed together. In a second aspect of the invention, there is provided a method for granulation of concentrated solutions by using a granulator with several impact blades arranged on arms on at least two shafts set in the desired feeding direction, whereby the shafts rotate in a trough , with an inlet at the beginning of the trough for the material to be treated an outlet at the end of the trough for removing the produced granulate, as well as entry nozzles for entry of fluid into the trough , comprising fluidizing mechanically the material to be treated by rotating impact blades , whereby a fused version of the product to be granulated is sprayed-on over the length of the treatment trough through feed nozzles to the generated particles-bed, feeding the fused material to the particle bed through the spraying nozzles as droplet mist, spraying-on the fused material through the spraying nozzles mainly vertically downwards between circular paths of the impact blades directly on to the particles-bed, and providing the shafts , the arms , and the impact blades with core holes, which serve as guides for heating or cooling agents. Thus, the granulator comprises a plurality of impact blade mechanically fluidizing the material to be treated, as well as feed nozzles over the length of the treatment trough for spraying a fused substance of the product to be granulated on the generated particles-bed. It is advantageous to feed the fused material through spray nozzles as droplets mist to the particles-bed, as similarly foreseen in an extension of the invention, whereby the fused material can be sprayed mainly vertically from the top through one, two or more rows of nozzles on to the particles-bed. By spraying- on the fused material it is possible to attain a largely homogeneous product; according to the method as per the invention, one can also prevent the tendency of agglutination. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS. Further features, details and advantages of the invention can be obtained from the basis of the following description as well as on the basis of the accompanying drawings. The following are shown: Fig. 1 A worm granulator or trough mixer as per the invention in side view, as twin shaft device; and Fig. 2 A principle view of a worm granulator in section. DETAILED DESCRIPTION OF THE INVENTION The worm granulator denoted with 1 generally in fig. 1 and 2 is a twin shaft worm granulator, whereby the invention is not only restricted to this design. The worm granulator 1 shown has a housing whose bottom part is mainly designed as a long stretched trough 2 with U-shaped cross-section. The housing cover 2a lies above on the edge of the trough 2 and closes it tightly. The interior of the housing is transported over the entire length of the housing by two horizontally arranged shafts 11 supported in the housing 2. During operation, the shafts 11 are brought into rotation by means of a drive 12. Each shaft 11 is provided with arms 10, whose center axis is vertical to the rotation axis of the shaft. On the outer end of the each arm 10, a scraper blade 3 is fixed. All arms 10 are equally long. While operating the worm granulator 1, the outer contours of the scraper blade 3 move on a covered cylindrical surface encompassing them. The inner surface of the floor bottom side of the trough 2 surrounds the cylinder surface at a distance of the manufacturing tolerances, which have to be maintained for contact-free running of the scraper blades 3, whereas the rising side walls of the trough 2 are finished plane and largely deviates back from the cylinder surface. The arms 10 are fastened in the shaft longitudinal direction in such a way oh the shaft 11 that the free ends of the arms 10 come to rest on a covered helix. The scraper blades 3 are slightly aligned to the level of the rotation paths covered by them. By means of a feeding stud 4 the fine material and/or the recycled material is fed to the worm granulator 1, and the treated product is removed by means of a discharge stud 5. On account of this arrangement of the scraper blade 3, the fragmented particles of the material being treated in the trough 2 get pushed in longitudinal direction of the trough: at the same time however, the particles within the heaping mechanism are rotated by the scraper blades and thoroughly mixed. Above all, even vertically moving components are pressed on to the particles. The worm granujator 1 as per the invention, in which a particles-bed is transported through with a determinable dwelling time duration and whereby the bed is at the same time intensively thoroughtly mixed, is particularly suitable to form enlarged granulates from the initially small particles, by adding fluid to the initial bed. In the moving bed the particles collide and with the help of the fluid get adhered to one another or are mixed together. In this invention the enlarging effect is intensified, in that a fused version of the material to be treated is sprayed on to the bed from the top. The fused material is fed to the worm granulator 1 as per the invention through the distribution pipeline 9. Fused material nozzles 6 are attached in the interior of the trough 2. Through their nozzle opening, the fused material is sprayed as droplet mist on to the bed. The two dash-dotted lines in fig. 1 indicating circles represent the path of the outer contours of the scraper blades 3. A special extension of the invention is obtained, if the fused material nozzles 6 or 6 spray vertically downwards between the circular paths of the scraper blades 3 directly on to the particles-bed. Fig. 1 shows such arranged fusion material nozzles 6. The shafts 11, the arms 10 and the scraper blades 3 can be provided with core holes, which serve as guides for heating or cooling agents. These are similarly brought into play'like the trough-shaped housing bottom part for heating or cooling of the particles-bed, whereby the housing is fitted with an outer jacket guiding a heating or cooling agent. WE CLAIM: 1. A method for granulation of concentrated solutions by using a granulator (1) with several impact blades (3) arranged on at least two shafts (11) set in the desired feeding direction, whereby the shafts (11) rotate in a trough (2), with an inlet (4) at the beginning of the trough (2) for the material to be treated and an outlet (5) at the end of the trough (2) for removing the produced granulate, as well as entry nozzles (6,8) for entry of fluid into the trough (2), Characterized in that: the material to be treated is mechanically fluidized by rotating impact blades (3), whereby a fused version of the product to be granulated is sprayed-on over the length of the treatment trough (2) through the feed nozzles (6) to the generated particles-bed; the fused material is fed to the particle bed through the spraying nozzles (6) as droplet mist; and the fused material is sprayed-on through the spraying nozzles (6) mainly vertically downwards between circular paths of the impact blades (3) directly on to the particles-bed. 2. A method for granulation of concentrated solutions by using a granulator (1) with several impact blades arranged on arms (10) on at least two shafts (11) set in the desired feeding direction, whereby the shafts (11) rotate in a trough (2), with an inlet (4) at the beginning of the trough (2) for the material to be treated an outlet (5) at the end of the trough (2) for removing the produced granulate, as well as entry nozzles (6,6) for entry of fluid into the trough (2), comprising fluidizing mechanically the material to be treated by rotating impact blades (3), whereby a fused version of the product to be granulated is sprayed-on over the length of the treatment trough (2) through feed nozzles (6,6) to the generated particles- bed; feeding the fused material to the particle bed through the spraying nozzles (6,6) as droplet mist; spraying-on the fused material through the spraying nozzles (6,6) mainly vertically downwards between circular paths of the impact blades (3) directly on to the particles-bed; and providing the shafts (11), the arms (10), and the impact blades (3) with core holes, which serve as guides for heating or cooling agents. 3. A method as claimed in claim 2, comprising providing a through-shaped housing bottom part (2) for heating or cooling of the particles-bed, whereby the housing is fitted with an outer jacket guiding a heating or cooling agent. The invention relates to a method for granulation of concentrated solutions by using a granulator (1) with several impact blades (3) arranged on at least two shafts (11) set in the desired feeding direction, whereby the shafts (11) rotate in a trough (2), with an inlet (4) at the beginning of the trough (2) for the material to be treated and an outlet (5) at the end of the trough (2) for removing the produced granulate, as well as entry nozzles (6,8) for entry of fluid into the trough (2). The material to be treated is mechanically fluidized by rotating impact blades (3); whereby a fused version of the product to be granulated is sprayed-on over the length of the treatment trough (2) through the feed nozzles (6) to the generated particles-bed, the fused material is fed to the particle bed through the spraying nozzles (6) as droplet mist; and the fused material is sprayed-on through the spraying nozzles (6) mainly vertically downwards between circular paths of the impact blades (3) directly on to the particles-bed.

Documents:

1669-KOLNP-2003-CORRESPONDENCE-1.1.pdf

1669-KOLNP-2003-CORRESPONDENCE-1.2.pdf

1669-KOLNP-2003-CORRESPONDENCE.pdf

1669-KOLNP-2003-FORM 27-1.1.pdf

1669-KOLNP-2003-FORM 27.pdf

1669-KOLNP-2003-FORM-27.pdf

1669-kolnp-2003-granted-abstract.pdf

1669-kolnp-2003-granted-claims.pdf

1669-kolnp-2003-granted-correspondence.pdf

1669-kolnp-2003-granted-description (complete).pdf

1669-kolnp-2003-granted-drawings.pdf

1669-kolnp-2003-granted-examination report.pdf

1669-kolnp-2003-granted-form 1.pdf

1669-kolnp-2003-granted-form 13.pdf

1669-kolnp-2003-granted-form 18.pdf

1669-kolnp-2003-granted-form 2.pdf

1669-kolnp-2003-granted-form 26.pdf

1669-kolnp-2003-granted-form 3.pdf

1669-kolnp-2003-granted-form 5.pdf

1669-kolnp-2003-granted-reply to examination report.pdf

1669-kolnp-2003-granted-specification.pdf

1669-kolnp-2003-granted-translated copy of priority document.pdf

1669-KOLNP-2003-PA-1.1.pdf

1669-KOLNP-2003-PA.pdf