SK126794A3 - Method of granulation of industrial fertilizer and device for carrying out this method - Google Patents

Abstract

This patent describes a device for granulation of synthetic fertilizer based on mixing of recycled powder part with melt or slip or another media (steam, water ammonium) in two screw granulator and the subsequent completing of granulation in a granulating or drying barrel, while the inlet part of it is arranged as a granualtor. This device consists of two screws and barrel granulator, serial connected, while the inlet part of two screws granulator is inserted in the inlet part of the granulating or drying barrel with an inlet part arranged as a granulator.

Description

Method of granulation of industrial fertilizers and equipment for its realization i.

Technical fields

The present invention relates to a process for wet granulation of industrial fertilizers with a melt, respectively. slurry and recycle and equipment for its implementation, consisting of a twin-screw and a drum granulator.

State of the art

Various methods of granulation are used in industrial fertilizer technology based on the use of different types of granulators (Granular Fertilizers, The British Sulfur Corporation, Ltd., Supplement Phosphorus Potassiun, London, 1985).

In most technologies, fertilizer components are obtained in the form of melt, respectively. suspension of sparingly soluble substances in saturated solution therefore, wet processes are used for their granulation. The most commonly used method of wet granulation of fertilizer salts is recycled granulation, consisting of combining small particles of recycle, respectively. Coating of the melt or slurry with vigorous stirring at a certain temperature and humidity. The resulting granulate is then dried and screened. The lining portion together with the crushed lining portion and any other ingredients are returned to the granulator as a recycle).

Intensive mixing of the melt or slurry with the recycle is ensured by the use of granulators of different design. The simplest and most commonly used are the drum and worm granulators. The disadvantage of drum granulators is their low efficiency and relatively low mixing effect. The optimum granulation area is then very narrow and the granulation system is sensitive to changing the parameters of the granulation process. The advantage is that there is a granulate with a spherical shape of granules, which usually has high mechanical strength and low sintering tendency.

Significantly greater mixing intensity is achieved with the use of twin-screw granulators. Their advantage is in particular the ability to vary the parameters of the granulation process over a relatively wide range without significantly affecting the quality of the granulate and the content of the product fraction, but the disadvantage is the relatively low mechanical strength and higher sinterability of the granulate due to irregular granular shape.

When using the above mentioned and also some other types of granulators, active granulation centers are formed in the granulators. maturing and stabilization, eventual granulation takes place in transport equipment or in the entrance part of the dryer. Longer transport distances result in energy loss and the possibility of escape of water vapor as well as undesirable substances into the working environment. On the other hand, when the dryer is installed immediately after the granulator, the active times of the drying time are intensively adhered to.

SUMMARY OF THE INVENTION

The disadvantages of the abovementioned granulation methods are eliminated by the process of granulating the industrial fertilizers according to the invention, which consists in first creating active granulation centers of the mixtures of recycled dust containing solid materials with melt or slurry of fertilizer salts and steam, water, scrubbing off-gases or ammonia, which are then fed into a granulation drum or a drying drum with an inlet portion adapted as a granulator, where they are granulated and stabilized. The melt is ammonium or potassium nitrate or sulphate, urea, any of the ammonium or potassium phosphates or mixtures thereof in any ratio, with a moisture content of 0 to 30%, preferably 0 to 15%, and the slurry contains ammonium or potassium nitrate, sulphate or chloride, urea, or one of the ammonium, calcium or potassium phosphates or polyphosphates and 0 to 50%, preferably 5 to 15% moisture. The granulating apparatus consists of a twin-screw granulator and a granulating or drying drum with an adapted inlet portion as a granulator, wherein the twin-screw granulator has an outlet portion inserted into an inlet portion of a serially connected drum granulator or a drying drum with a modified inlet portion as a granulator.

The process of granulation of industrial fertilizers according to the invention combines the advantages of granulation in a twin-screw and drum granulator. The process provides a granulate with a spherical granule shape and high mechanical strength, with a high production fraction content over a relatively wide range of gr einulation parameters. The two-width granulator can be placed on the ejection structure, allowing the length of the stabilization zone to be varied within a certain range as required, thereby actively influencing the granulation process conditions. The insertion of the outlet part of the screw granulator into the inlet parts of the drum granulator or of the drying drum with a modified inlet part as a granulator allows to achieve maximum granulation efficiency in both devices, since the granulate does not stabilize and energy losses during its transport.

Using the L (n twin-screw granulator), higher granular homogeneity and granulometric composition is achieved to form active granulation centers. Moving the stabilization zone into the drum granulator or granulator inlet portion prevents the active granule particles from sticking to the assembly. The spherical shape of the granules and their more efficient drying reduces the need for granulate surface treatment agents and increases the sintering resistance of the fertilizer. influencing the chemical composition and mechanical properties of the granules, which makes it possible to produce a full range of fertilizers from single to three-component type NPK on this plant.

Clarification of drawings

The granulating device according to the invention is shown in FIG. 1 and 2, which also implies a method for granulating industrial fertilizers. In FIG. 1 is a whole granulation device consisting of a twin-screw granulator 1 disposed on a slide-out structure 3 which is moved on rails 8 with an outlet part inserted into a series-connected granulation drum 2.

In the inlet part of the twin-screw granulator 1 there are openings for feeding granulation media: recycled dust fraction 4, melt or slurry of fertilizer salts 5 and optionally steam or ammonia 6, water or sludge from scrubbing gas 7, possibly other components. In FIG. 2 is a second embodiment of a granulation device consisting of a twin-screw granulator 1 with its outlet part embedded in a drying drum at the inlet part, configured as a granulation drum 2. In the inlet part of the twin-screw granulator 1 there are openings for feeding granulation media: recycled dust 4 , melt or sludge of fertilizer salts 5 and optionally steam or ammonia 6, water or sludge from scrubbing 7, or other components.

Example

A 130 t / h recycle consisting of an undersized and crushed supernatant of dolomite ammonium nitrate granulate (LAD) and solid state ingredients - ammonium sulfate and dolomite with a temperature of 91 ° C with 39.4 t / h of melt were fed and blended into the continuously operating twin-screw granulator. ammonium nitrate with a moisture content of 3.1% and a temperature of 156 ° C, 0.5 t / h of water vapor at a temperature of 145 ° C and 0.1 t / h of a scrubber sludge with a temperature of 52 ° C and a moisture content of 50%. ° C formed active granulation centers, which were led into a granulation drum for granulation and stabilization. The stabilized granulate with a spherical granule shape and a moisture content of 1.1% was fed into a built-in drying drum, where it was dried with heated air. At the outlet of the dryer 16S t / h of granulate was obtained with a moisture content of 0.39% and a granulometric composition:

Granulometric content fractions 0 to 2 mm 22% · II fractions 2 to 4 mm 44% · H fractions over 4 mm 34%

Claims (4)

Process for granulating industrial fertilizers (1), characterized in that they first form active granulation centers in a twin-screw granulator by mixing recycled dust containing solid materials with the melt and / or slurry of fertilizer salts and steam and / or water and / or sludge from scrubbing offgases and / or ammonia, which are then fed into a granulation drum and / or a drying drum with an inlet portion adapted as a granulator, where they are granulated and stabilized. 2. Process for granulating industrial fertilizers according to claim 1, characterized in that a melt of ammonium or potassium nitrate or sulphate, urea or one of the ammonium or potassium phosphates or a mixture thereof in any ratio, with a moisture content of 0 to 30%, preferably 0 to 15%. 3. The fertilizer granulation method according to claim 1, characterized in that a slurry containing nitrate and / or sulphate and / or ammonium and / or potassium chloride and / or urea and / or one of the phosphates and / or ammonium polyphosphates is used and and / or calcium and / or potassium containing 0 to 50%, preferably 5 to 15% moisture. 4. An apparatus for granulating industrial fertilizers, consisting of a twin-screw granulator and a granulating or drying drum with a treated inlet portion as a granulator, characterized by. The twin-screw granulator has an outlet portion inserted into an inlet portion of a drum granulator or a drying drum with a treated inlet portion as a granulator.