SU1114457A1 - Method of applying protective coating on granular materials - Google Patents

Abstract

THE METHOD OF DRAWING A PROTECTIVE COATING ON GRANULAR MATERIALS, including the creation of a flowing layer of granules, the dispersion of a coating solution from top to bottom on a layer of granules, characterized in that 0 diameter fountain. (L with 4 41 JV s |

Description

The invention relates to the technology of obtaining granulated mineral fertilizers and coated salts, in particular, to a method for applying a protective coating to granular materials. There is a known method of applying a protective coating on granular materials, which includes creating a flowing layer of granules, spraying the coating solution from top to bottom on a layer of granules. Spraying of the coating leads to an annular zone bounded by the wall of the apparatus and the fountain 111. A disadvantage of the known method is the insufficiently high uniformity of the coating on the granules and the relatively high dustiness. The purpose of the invention is to improve the uniformity of the coating and reduce the dustiness. The goal is achieved by the fact that according to the method of applying a protective coating on granular materials, including creating a flowing layer of granules, spreading the coating solution from top to bottom on a layer of granules, spraying the solution is carried out in a zone equal to 1.3-2.0 diameter fountains. the implementation of the proposed method. The apparatus includes a housing 1 of conical shape with fittings 2 and 3 for the inlet and outlet of the coolant and fitting 4 for unloading the finished product. In the lower part of the housing 1, a gas distribution grid 5 is installed to create a flowing layer and maintain a layer of granules. In the upper part of the housing 1 there is a spray device 6 for supplying the coating composition in the form of a suspension or solution. The device operates as follows. In case 1, a granular product is loaded, for example, a mineral fertilizer. Through the interchangeable diaphragm 7 of the grill 5, hot air is supplied for the fluidized bed of the granules 8. The air speed is increased until the fluidized bed passes into the flowing mode with the formation of the idecentral fountain 9 and the peripheral layer 10. The composition of the coating in the form of a suspension or solution is fed through a dispersing device 6 the height of which is adjusted in such a way that the diameter of the irrigation zone is 1.3-2.0 times the diameter of the fountain. The proposed irrigation area, equal to 1.3-2.0 times the diameter of the fountain, provides a protective coating for granules of higher quality. Content an. lomerized product is reduced from 6.0% to 4.0-5.5%. The average deviation in the weight of the granules varies from 10% to 5.0-9.5%. An increase in the irrigation area of more than two fountain diameters leads to deterioration of the process conditions. The coating is sprayed onto the less active, less mobile part of the fluidized bed, the granules of which, before getting into the fountain, have time to partially stick together. The percentage of agglomerated particles increases, the average deviation in the weight of the granules increases with an equal degree of dust, as compared with the known method. By limiting the irrigation area to less than 1.3 the diameter of the fountain, the dusting significantly increases. The agglomeration of the product increases, caused by an increase in the density of irrigation, and the average deviation in the weight of the granules increases, i.e., i.e. coating uniformity is reduced. Example 1. A cylindrical apparatus with a cylindrical part diameter of 300 mm, a conical part height of 400 mm, a chamber height of 900 mm is loaded with 1.0 kg of granulated urea of a fraction of 2-3 mm, a moisture content of 0.5%. Through a replaceable diaphragm having a central opening with a diameter of 70 mm, fluidizing air is supplied with a temperature of 120 ° C to form a fountain. The height of the fluidized bed of granules (4i 1) is 90 mm. The temperature of the fluidized bed is 85 ° C. The protective coating on the granules is applied using a pneumatic nozzle installed above the active central part of the fluidized bed fountains, axially to it. Dissolution angle (d-) nozzle - 60 °. The diameter of the fountain is 70 mm. The diameter of the irrigation zone is taken to be 1.2 s of the fountain, i.e. 84 mm. Spray nozzle, poured at a height of 3.0, 90 ° - ° - about 235 mm. As a protective coating, 3 dicalcium phosphate in the form of a suspension with a concentration of 40% is used. The irrigation density is 21.3 g / min. See Experiment Time 20 min. By estimating the inhomogeneous coating of a relative, the relative absolute value of the L shell mass is determined as follows: where n is the number of samples, n is the mass of the film of the 8th part, and h is the average arithmetic mass of the shell of particles of the sample. PRI mme R 2. Same as in process 1, but 1.2 kg of urea is loaded into the chamber of the apparatus. The height of the fluidized bed is 100 mm. The spray angle of the nozzle is 70 °. The diameter of the irrigation zone is set to 1.3 fountains or 91 mm. The nozzle is installed at a height of 230 mm from the level of the diaphragm. Irrigation density 19.6 g / min-cm Test time 24 min. Example Same as in product 1, but 1.5k urea is loaded into the chamber. The height of the fluidized bed is 120 mm. The spray angle is 70. The diameter of the irrigation zone is set at 1.7 fountains or 119 mm. The nozzle is installed at a height of 290 m from the level of the diaphragm. Irrigation density - 15.0 g / min. Cm. Test time 30 min. Example4. Same as in example 1, but in the camera load 1.5 kg of urea. The height of the fluidized bed is 120 mm. The spray angle of the nozzle is 60. The diameter of the irrigation zone is 2.0 fountain or 140 mm. The nozzle is installed at a height of 360 mm from the level of the diaphragm. The density of the orogeny is 12.8 g / min. CM. Experience time 56 min. PRI me R 5. Same as in Clause 1. 1.5 kg of Chevina is loaded into the chamber. The fluidized bed height is 120 mm. Spray angle of a 70 ° sprayer. Irrigation area diameter 2, 1 fountain or 147 mm. The nozzle is stopped at a height of 330 mm from the ur n diaphragm. Irrigation density 12.2 g / min-cm. Test time 30 min. The conditions of the experiments and the results are shown in Table 1. 574 As can be seen from the examples of the specific implementation of the process according to the proposed method, the best results on the quality of the protective coating are obtained by spraying the protective coating on the active part of the fluidized bed of granules in the central axial zone of the apparatus in the irrigation area equal to 1.3-2.0 of the fountain diameter. Comparison of the results of the process according to the known and proposed methods are given in Table 2. From Table 2 it can be seen that with the active part of the fluidized bed of the fountain in the central paraxial zone of the apparatus, onto which the coating is sprayed axially to the fountain with the formation of an irrigation area equal to 1.3-2.0 of the diameter of the fountain, the height of the spray device is adjusted by the formula taking into account the diameter of the fountain, the degree of loading of the apparatus and the spray angle of the device, which makes it possible to obtain granulated urea with a coating of better quality, i.e. with a smaller average deviation in the weight of the granules (5–9.5%), a lower content of agglomerated granules (3.2–4.5%) and a dust content of 4–5.5%, which is 0.5–2.0% lower dust removal by a known method. In addition, the process of applying a protective coating is easily adjustable to meet changing conditions (fountain diameter, loading height, spray pattern). As a base object for comparison, a method of obtaining granular materials was selected, according to which the coating process is carried out in a fluidized bed of granules in the classical mode (a conventional fluidized bed of granules without formation of a fountain. To reduce the tendency of the product to agglomerate, the granulated product must be recirculated separated in the fluidized bed, which requires a more complex instrumentation process. Comparative data on The basic and baseline methods are listed in Table 3. In carrying out the process of applying a protective coating according to the proposed method, as compared to the base method, the content of agglomerated granules decreases by 0.5-1.8%, the yield of the target product increases by 5-8%, decreases pypeunos by 4.5-16%.

The expected economic effect from the use of the invention is 180-480 thousand rubles / year with the release of 100,000 tons per year.

Table 1

9060701, 23511.0

10070701, 2308.0

10070701, 2905.0

12060702, 3609.5

12070702.1 14733010.5

Known method

Koltsev

10 irrigation zone between the wall of the apparatus and the fountain

The proposed method

1.3 1.7 2.0

7.0 5.5 4.0 5.0 6.0

Table 2

3.0

6.0 8.0

5.5 5.0

4.0 9.5 5.0

The basic method 10-2075-85

The proposed method 4-5,590-93

Table 3

5.0

3.2-4.5

Claims (1)

METHOD FOR APPLYING PROTECTIVE COATING ON GRANULAR MATERIALS, including creating a flowing layer of granules, spraying the coating solution from top to bottom on the granule layer, characterized in that, in order to increase the uniformity of the coating, reduce dust, the solution is sprayed into a zone equal to 1.3-2, 0 diameter of the fountain. I