JPH0327512B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a granular fertilizer and a method for producing the same. More specifically, the present invention relates to a granular fertilizer obtained by mixing powdered fertilizer (excluding potassium sulfate) with a small amount of water in which a surfactant is dissolved or dispersed, and compressing and granulating the mixture, and a method for producing the same. Generally, granulation of fertilizers in recent years has been carried out for the purpose of improving fertilizer application workability and adapting to mechanical fertilization.
Today, most of the compound fertilizers are used in granular form. However, many simple fertilizers are still used in powder form. On the other hand, granulated simple fertilizers are used in bulk blend fertilizers, which have recently become popular. Currently, various types of fertilizers are granulated using methods suited to their physical properties and provided to the market. For example, granular urea is prilled in a prill tower or granulated in a granulator by a known method,
Granular products are also available for superphosphate or heavy superphosphate. On the other hand, for fertilizers other than those mentioned above (excluding potassium sulfate, the same applies hereinafter), such as potassium chloride, ammonium sulfate, and ammonium chloride, there is a demand for effective granulation methods and provision of granular fertilizers. The above-mentioned fertilizers are generally produced by a compression granulation method, such as a method in which compression is performed using a roll press or the like, followed by disintegration and sieving, except in cases where a special granulation method has been established, such as in the case of urea. However, regarding the granulation of granular fertilizers, particularly single fertilizers, there are various manufacturing and quality problems as described below. For example, in a dry granulation method in which powdered potassium chloride is mixed with a small amount of water and then compressed into granules, the granulation properties of the potassium chloride are poor;
It is difficult to efficiently obtain granular products with a desired particle size range. When granular potassium chloride obtained by compressing and granulating a potassium chloride-water mixture using a roll press or the like is used as the raw material for the bulk blend fertilizer described above, granular chloride is produced during handling and transportation of the resulting bulk blend fertilizer. As a result of the pulverization of the potash portion, classification of the bulk blend fertilizer occurs, and segregation of fertilizing components by particle size becomes a problem. Incidentally, as a raw material for compound fertilizers or bulk blend fertilizers based on organic fertilizers, 6 to 12 meshes of granular potassium chloride (note: the same applies to other single fertilizers) is generally used. In such applications, the granular potassium chloride obtained by the above-mentioned compression granulation method has undergone a process of compression, disintegration, and sieving, so its surface has many protrusions and its compression hardness is relatively high. The crushing surface is prone to wear. During handling and transportation of the granulated product,
Powdering from the fragile side of the individual particles occurs. Potassium chloride compressed and granulated using a roll press using the conventional method is used as a raw material for bulk blend fertilizer, but the pulverization rate of this product is approximately 10%, which is the average powder for practically usable granular fertilizers. This is significantly higher than the 2-3% conversion rate. For this reason, granular potassium chloride and other simple fertilizers related to compression granulation are re-sieved before bulk blending, and there is a demand for granular fertilizers that do not require re-sieving. Fertilizers are generally used in their raw form, but when farmers apply fertilizers such as potassium chloride, powdered fertilizers or fertilizers that contain a large amount of powdered substances generate dust, which can be harmful to the working environment. Harmful. In addition, potassium chloride that does not contain powdery substances is required because it is dispersed by wind, etc., which causes loss during fertilization and uneven fertilization. Therefore, for general farmers, it is necessary to keep the particle size as fine as possible so as not to generate dust during fertilization, but to prevent uneven fertilization. As a result of various studies in order to produce the above-mentioned desirable granular fertilizer, the present inventors have discovered that by mixing a small amount of water in which a surfactant has been dissolved or dispersed with powdered fertilizer, and compressing and granulating the mixture. The present invention was completed knowing that the above-mentioned problems could be solved. As is clear from the above description, an object of the present invention is to provide a compression granulation method for fertilizer with a good granulation effect, and a fine granular fertilizer produced by the method that is less likely to be powdered during use. It is in. The present invention has the following main configuration (1) and embodiment configurations (2) and (3). (1) Powdered fertilizers such as potassium chloride, ammonium sulfate, ammonium chloride, ammonium phosphate,
Superphosphate lime, heavy superphosphate lime, heavy burnt phosphorus, 2
- Mix one or more fertilizers selected from oxo-4-methyl-6-ureidohexahydropyrimidine, isobutylidene diurea, oxamide, urea-formaldehyde condensed fertilizer and a small amount of water in which a surfactant is dissolved or dispersed. , a granular fertilizer obtained by compressing and granulating the mixture. (2) Adding surfactants to granular fertilizer and the fertilizer
0.001-20% by weight dissolved or dispersed water
The granular fertilizer according to item 1 above, which is mixed with 0.03 to 1.0% by weight. 3. The granular fertilizer according to item 1 above, wherein the surfactant is one or more selected from anionic surfactants, cationic surfactants, amphoteric surfactants, and nonionic surfactants. As the powdered fertilizer used in the present invention, fertilizers other than potassium sulfate described below can be used.
That is, they are, for example, potassium chloride, ammonium sulfate, ammonium chloride, ammonium phosphate, lime superphosphate, lime superphosphate, heavy calcined phosphorus,
2-oxo-4-methyl-6-ureidohexahydropyrimidine (trade name: CDU), isobutylidene urea (trade name: IBDU), oxamide or urea-formaldehyde condensation fertilizer, or a combination of two or more of these fertilizer ingredients can be used. The degree of powderiness, that is, the particle size, of such fertilizer raw materials for granulation is not limited, and either granules, powders, or a mixture thereof can be used. however,
In relation to the particle size of the target product, usually 60 mesh passes or less, preferably 80 mesh passes or less 300
It's about the same level or higher. In the above explanation, the significance of granulating granular fertilizer as a raw material lies in the difference in physical properties (hardness, pulverization rate, etc.) between the raw material granule and the product granule. Compression granulation according to the present invention is possible even if coarse particles such as 60 mesh are used, but the yield of granular products may be lowered because the miscibility with water in which the surfactant is dissolved or dispersed is somewhat reduced. There is a tendency for the powdering rate to decrease somewhat and the powdering rate to increase slightly. The surfactants used in the present invention include anionic surfactants that dissolve or disperse in water;
Any of cationic, nonionic and amphoteric surfactants can be used. However, the type of these surfactants is selected and used in accordance with the chemical properties of the fertilizer to be applied. For example, when anionic surfactants are applied to fertilizers containing large amounts of divalent or trivalent metal ions, such as lime superphosphate, the surfactants react with these metal ions and become insolubilized. However, the surfactant effect is impaired. Therefore, it is desirable to use nonionic surfactants for such fertilizers. The surfactant is used by dissolving or dispersing it in water in a predetermined amount, and the concentration of the surfactant in the aqueous solution or dispersion thus obtained is 0.001 to 50% by weight, preferably 0.05 to 20% by weight. . If the amount is less than 0.001% by weight, the effect of the present invention is insufficient, and if it exceeds 50% by weight, not only will the effect not be improved, but the viscosity of the water in which the surfactant is dissolved or dispersed will increase, resulting in Miscibility with powdered fertilizers: For example, when the surfactant liquid is sprayed onto granular potassium sulfate, it is difficult to form fine droplets into a mist, which is not preferable. The method of mixing the powdered fertilizer used in the present invention with a small amount of water in which a surfactant is dissolved or dispersed is not limited as long as the mixing can be carried out uniformly. For example, the surfactant (or dispersion) is sprayed onto powdered fertilizer that is being stirred or fluidized in a mixing vessel, or the above-mentioned mist is sprayed onto powdered fertilizer falling inside a tower. . The ratio of water used as a surfactant solution (or dispersion) to the powdered fertilizer is 3% by weight or less, preferably 0.01 to 1.0% by weight, and more preferably 0.1 to 0.7% by weight. When the proportion of water used in the compression granulation (dry compression granulation) according to the present invention is larger than the above-mentioned range, undesirable physical properties of the granular fertilizer product, such as increased caking, will occur. In addition, the effect of improving powderability becomes insufficient, and a separate drying step is required to prevent this, and one of the advantages of the dry method is lost. On the other hand, if the proportion of water used is less than 0.01% by weight, it will be difficult to evenly wet the surface of the powdered fertilizer raw material with the surfactant solution (or dispersion), resulting in improved granulation efficiency and Both the improvement in the chemical properties and the chemical properties are insufficient. As an exception to the above usage ratio of water and powdered fertilizer, when two or more powdered fertilizers are mixed and moistened, double chlorination and other reactions progress between some of the fertilizer ingredients, and the mixed water A larger amount of water may be required as some of the water is fixed as water of crystallization. The conditions for mixing the surfactant solution (or dispersion) and powdered fertilizer are not limited, but may be from room temperature to 100℃.
for 5 minutes to 1 hour (in case of batch method) or
The contact time is about 10 seconds to 3 minutes (contact time in the case of continuous method). The powdered fertilizer-surfactant solution (or dispersion) mixture according to the present invention obtained as described above is subsequently fed to a compression granulator and granulated. The granulator used is not limited, but
Examples include roll presses, briquetting machines or tablet machines. however,
The effects of the present invention are particularly remarkable when a roll press is used. Incidentally, roll press refers to a method in which a pressure of several tons/cm ² is applied to the rolls used, and the raw material to be granulated is passed between the rolls, compressed, and then crushed to obtain a granular product. The thus obtained crushed product is separated into preferred particle sizes using a sieve, such as a vibrating sieve, and those with suitable particle sizes are obtained as products. In the case of the granular fertilizer according to the present invention, examples of the particle size include 6 to 12 mesh (granular product) and 12 to 12 mesh (granular product).
60 pieces (fine grain product). 6 to 12 means 6 mesh passes and 12 mesh passes.
The 12 meshes that separate grain products from fine grain products may be of other sizes (for example, 24 meshes) depending on the case. In the case of the aforementioned particle sizes, oversized products of 6 mesh passes or undersized products of 60 mesh passes are crushed or re-roll pressed as required. However, fine-grained products that can be applied directly to the field as simple fertilizers, e.g.
If mesh is desired, additional sieving is performed on the 60 mesh pass portion. With regard to this additional sieving, compression granulated products using the conventional method tend to clog the sieve and cannot be used for long periods of sieving, but the method of the present invention has very little clogging, so Fine-grained mesh products can also be manufactured without any problems. The above steps will be explained using figures. In the figure, the fertilizers supplied from pipes 1 and 2 are mixed in mixture A, which is passed through pipe 4 and spray nozzle B in an intermediate falling state to hopper C via raw material supply pipe 3. The atomized surfactant aqueous solution or water is sprayed on the surface of the product to make it wet, and then the product is sent to hopper C. The wet particles in the hopper C are sent to a screw feeder D via a pipe 3' and are subsequently fed to a roll press E to form flakes. The flakes are sent to a crusher F via a belt conveyor 5 and crushed,
The mixture of granules and powder is sent to the vibrating sieve G through the bucket elevator 6. The vibrating sieve contains 6 meshes from the top (same for Tyler and below),
12 mesh and 60 mesh sieves are installed. The mixture treated with this sieve is sieved into oversized products, granular products, fine granular products, and return powder in the order of particle size. The oversized products then pass through the oversized product piping 8 to the crusher F.
The returned powder is returned to the supply pipe 3 to the hopper C via the return powder pipe 7. Other granular products and fine granular products are obtained as products from product piping 9 and product piping 10, respectively. The first effect of the present invention is that the efficiency of granulation is good. That is, as is clear from Example 2 and Comparative Examples 3 and 4, which will be described later, the efficiency of granulation by the method of the present invention is 80% for both granular and fine granule products.
However, the efficiency does not reach 60% even when carried out in the same manner as the method of the present invention except that no water or the like is added or only a small amount of water is mixed. The second effect of the present invention is that the obtained granular product has high hardness and a low powderization rate. That is, Examples 1, 3 to 5 and Comparative Examples 1, 2, 5 to
As is clear from No. 10, the hardness (compression rupture pressure) of the product of the present invention is approximately 20 to 40% higher than the corresponding comparative examples, and the powdering rate is as low as 1 to 2%, which is lower than that of the comparative examples No. 4 to 4. significantly less than 7%. The present invention will be explained below with reference to Examples and Comparative Examples. Example 1, Comparative Example 1 While mixing industrial potassium chloride using a mixer, 0.5% by weight of a nonionic surfactant (hexaoxyethylene n-octylphenyl ether) was added.
The dissolved water was 0.3% by weight relative to the potassium chloride and mixed by spraying with a sprayer. The resulting mixture was rolled pressed (Alexander type, Wp400×400
compressed under piston oil pressure of 300Kg/ ^cm2 using
It was made into flakes. The resulting flakes were crushed using a crusher, and the crushed products were then sieved using a vibrating sieve to obtain 6 to 24 mesh (Tyler) granules, and the hardness and pulverization rate of the granules were measured. In addition, for comparison of the effects of the present invention, a case where no aqueous solution of surfactant was used (Comparative Example 1) and a case where the same amount of water as the solution was used instead of the aqueous solution of surfactant (Comparative Example 2) For each, granular products were obtained under the same conditions except for the hardness and powdering rate were measured. Table 1 shows the compression granulation conditions and the measurement results of hardness and powdering rate.

[Table] Example 2 and Comparative Examples 3 to 4 A nonionic surfactant (hexaoxyethylene n-octyl phenyl ether) was added to the raw material of industrial potassium chloride and the powder returned from the granulation process.
Add 0.5% by weight of water to the sample.
It was mixed by spraying with a wt% sprayer. The amount of raw materials supplied to the roll press, including the returned powder, is 2.0
The amount of raw material also corresponds to the total amount of granules and fines, ie, the product amount. The resulting mixture was set at a constant volume (2.0 tons/hour) using a screw feeder, and was continuously fed to a roll press (Alexander type, WP400×400 type), where it was compressed under a piston oil pressure of 300 Kg/ ^cm2. It was granulated into flakes. The obtained flakes are crushed with a crusher, and the crushed products are passed through a vibrating sieve (6 meshes in the upper row, 12 meshes in the middle row).
60 meshes in the lower row, each sieve area 2.8 square meters) to separate the grains from 6 to 12 meshes.
Fine particles of 12 to 60 mesh were obtained. The oversized 6-mesh sieve is crushed again in the crusher,
Also, 60 mesh sieve undersize product (return powder)
is a continuous operation device that circulates to the roll press, and its outline is shown in the attached diagram. The obtained granules and fine granules were each stored in silos with a capacity of 50 tons, then filled into flexible containers and weighed, and the proportion of powder mixed into the fine granules was measured. In order to compare the effects of the present invention, the other conditions were the same for the case where no surfactant aqueous solution was used (Comparative Example 3) and the case where the same amount of water was mixed with the surfactant aqueous solution (Comparative Example 4). and compressed and granulated.
I took measurements. The results are shown in the table.

[Table] Examples 3 to 5, Comparative Examples 5 to 10 Industrial ammonium sulfate, CDU (trade name) and CDU (trade name) containing phosphorus (15-15-15-0) (instead of industrial potassium chloride) Product name) is used as raw material,
As shown in the table, the types of surfactants,
Table 1 shows the results of obtaining granular products in the same manner as in Example 1 and Comparative Example 1, and measuring the hardness and powdering rate, except for mixing at the concentration and mixing ratio.

【table】

【table】 [Brief explanation of drawings]

The figure is a flow sheet showing the manufacturing process of the method of the present invention. In the figure, A... mixer, B... spray nozzle, C... hopper, D... screw feeder, E... roll press, F... crusher, G...
... vibrating sieve, 3: raw material supply piping, 5: belt conveyor, 6: bucket elevator, 7: return powder piping, 8: oversized product piping.

Claims (1)

[Scope of Claims] 1 Powdered fertilizers including potassium chloride, ammonium sulfate, ammonium chloride, ammonium phosphate, lime superphosphate, heavy superphosphate lime, heavy calcined phosphorus, 2-oxo-4-methyl-6-ureidohexa Granules obtained by mixing one or more fertilizers selected from hydropyrimidine, isobutylidene diurea, oxamide, and urea-formaldehyde condensed fertilizer with a small amount of water in which a surfactant is dissolved or dispersed, and compressing and granulating the mixture. fertilizer. 2 Adding a surfactant to the granular fertilizer and the fertilizer
0.001-20% by weight dissolved or dispersed water 0.03
The granular fertilizer according to claim 1, which is mixed with ~1.0% by weight. 3. The granular fertilizer according to claim 1, wherein the surfactant is one or more selected from anionic surfactants, cationic surfactants, amphoteric surfactants, and nonionic surfactants. .