JPH0229639B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for granulating fused phosphorous fertilizer. With the progress and spread of approximation, modernization of agriculture, and mechanization, the majority of the fertilizers used have come to be in the form of granules, which are easy to remove. On the other hand, most of the molten phosphorus fertilizer is still sandy.
Consumer demands, which are rooted in ease of handling and good workability, are not necessarily met. In other words, fused phosphorus fertilizer (hereinafter referred to as Yorin) is
As a property derived from its manufacturing, it may have a flickering feel when handled due to the contamination of needle-like items.
It has drawbacks such as being heavy with a bulk specific gravity of 1.6 or more and being sandy, making it difficult to work with.Therefore, there has been a desire to improve these properties. However, although Yorin has the above-mentioned drawbacks, it is widely recognized for its excellent effectiveness as a soil conditioner, and its use is far greater than that of other fertilizers. . Under these circumstances, many methods for granulating yorin have been proposed, but no satisfactory method has yet been established. Conventional granulation methods include, for example, a method in which phosphoric acid lime, which has a high caking force obtained by reacting phosphate rock powder with sulfuric acid, is mixed with yorin and granulated (Japanese Patent Publication No. 37-8525, Japanese Patent Publication No. 37-10532), granulation method using fibrous lignin obtained during wood pulp production as a binder (Special Publication No. 49-13273), urea and ammonium chloride or potassium chloride are themselves fertilizer components. A method of mixing and granulating materials with good caking power with Yorin (Special Publication No. 42-25179,
(Special Publication No. 47-119829), Method of granulating sodium tripolyphosphate as a binder (Special Publication No. 39-13022) A method of mixing and extruding granulation (Japanese Patent Publication No. 49-115855), a method of granulating by spraying a neutral suspension obtained by adding seasoning waste liquid and ammonium phosphate to powdered yorin (Japanese Patent Publication No. 1973-11585) −
27840), a method of reacting phosphoric acid with phosphoric acid and granulating it using a specific horizontal cylindrical rolling device (Japanese Unexamined Patent Application Publication No. 1983-1999-
116690), a method of reacting phosphoric acid with a specific conductivity of 0.20Ω ^-1 cm ^-1 or less and containing 47% by weight or more as P ₂ O ₅ using an inverted conical screw mixer, and granulating it ( JP-A-55-116691), etc. However, these methods dilute the fertilizing ingredients due to the addition of too much binder and reduce the fertilizing effect, the granulation cost is too high, and the expression of water-soluble components makes it difficult to use other types of fertilizer (mixed phosphorus fertilizer). ) to convert into
Therefore, it is not necessarily a preferable method for obtaining granular products that are inexpensive and meet the standards for yorin. The present inventors investigated various methods of granulating Yorin without the drawbacks mentioned above, and found that the particle size was 2 m/m.
Hereinafter, we have found a method for obtaining granulated yorin that has a bulk specific gravity of about 75% of conventional yorin and maintains various properties originally found in yorin. That is, the present invention provides a method for granulating yorin by reacting yorin with a mineral acid, in which a mineral acid containing an ammonium compound is added in an amount of 0.5 to 5% by weight based on yorin in terms of acid anhydride. This is a method for granulating Yorin characterized by using % More specifically, the present invention involves liberating the soluble silicic acid originally possessed by Yorin with one or more mineral acids such as sulfuric acid, hydrochloric acid, phosphoric acid, and nitric acid, and using it as a binder. , and is characterized in that the amount of liberated silicic acid is kept to the minimum necessary, and furthermore, an ammonium compound is contained in the mineral acid. The amount of mineral acid used here is preferably as small as possible in order to liberate the silicic acid that will act as a binder necessary for granulation, and the amount is calculated in terms of acid anhydride. 0.5 to 5% by weight,
Preferably it is 1 to 4% by weight. The concentration of the mineral acid used varies depending on the moisture used and the required amount of mineral acid, but is suitably 5 to 40% by weight. If the amount of mineral acid used exceeds 5% by weight based on the yorin, the amount of water-soluble components in the resulting granular yorin will increase dramatically, and the original water-insoluble property of yorin will be lost, as well as the residual Because silicic acid gels,
Although it significantly insolubilizes soluble silicic acid and makes granulation easier, it results in a fertilizer that deviates from its original characteristics as a soil conditioner. On the other hand, when the amount of mineral acid used is less than 0.5% by weight, free silicic acid as a binder is insufficient, and the properties that a granular product should have, such as crushing strength and pulverization rate characteristics, cannot be satisfied. Next, the action of the ammonium compound contained in the mineral acid, which is a feature of the present invention, will be explained. The ammonium compound dissolved in mineral acid has the following effects when the yorin is granulated and dried into a product. That is, ammonium ion (NH ₄ ⁺ ) in mineral acid reacts with mineral acid and yorin,
It exhibits a buffering effect, suppressing the water solubilization of components such as phosphoric acid, magnesia, and lime in yorin, and ammonium compounds that come into contact with mineral acids and unreacted yorin during the drying stage of granules. Depending on the degree of contact, some or all of the ammonia gas is decomposed and volatilized as ammonia gas, which causes the material to be granulated to become porous. This action and effect are particularly effective within the range of use of mineral acids specified above, and the effect of suppressing water solubility is remarkable compared to the conventional reaction and granulation with mineral acids alone. A reduction of more than 15% is possible compared to that obtained by the conventional method using only mineral acids. When the bulk specific gravity is reduced, for example, when mixing this with other fertilizers, there is an advantage that they can be mixed uniformly. In the present invention, the content of ammonium compounds in mineral acids is 0.1 in terms of ammonium ion (NH ₄ ⁺ ).
~4% by weight is preferred. When the content exceeds 4% by weight, the degree of contact with the raw material yorin, that is, the degree of association, decreases, the volatilization rate of ammonia gas decreases, and therefore the effect does not improve, and on the contrary, unreacted ammonium compounds However, this is not preferable as it results in dilution of the fertilizing ingredients. Moreover, if the content is less than 0.1% by weight, the action is weak and sufficient effects are not exhibited, which is not preferable. Ammonium compounds contained in mineral acids include ammonium salts of inorganic acids such as ammonium sulfate, ammonium chloride, ammonium phosphorus, and ammonium nitrate, or acid salts thereof; ammonium complex salts such as Mohr's salt, iron ammonium alum, ammonium alum, and chromium ammonium alum; It is obtained from urea and can be used alone or in combination. According to the present invention, the type of machine used for reaction and granulation is not particularly limited, and can include a general bread type, drum type,
A kneader type granulator or mixer may be used. In addition, since the granulated material can be used as it is in the form of sand, there is no need to pulverize the fertilizer as in the past, which shortens the process. In addition, the resulting granular fertilizer uses the silicic acid contained in the fertilizer itself as a binder, and since the ammonium compound exhibits the above-mentioned effects, there is extremely little loss of fertilizing components due to granulation. In addition, although the obtained granular fertilizer has a small particle size of 2 m/m or less, it has a bulk specific gravity of 1.1 to 1.2 (g/cm ³ ), which is very light, and it is difficult to handle because it does not have needles. A fertilizer with extremely good workability can be obtained without causing any pain. The present invention will be explained below with reference to Examples and Comparative Examples. Example 1 Sand-like yorin having the following chemical composition and particle size distribution and 1% by weight in terms of ammonium ion
phosphoric acid solution containing ammonium sulfate and having a concentration of 20% by weight calculated as P ₂ O ₅ at a rate of 100 kg/hour and 15 kg/hour, respectively, and rotating at a circumferential speed of the blades of 0.6 m/sec. When the mixture was continuously fed, reacted, granulated and dried, granular yorin with the following properties was obtained at a rate of 103 kg/hour.

【table】

[Table] Obtained granular Yorin at 0.21 m/m and 2 m/m
When the grains were sieved using a sieve, the bulk specific gravity was 1.17 (g/cm ³ ) compared to 1.55 (g/cm ³ ) for sandy yorin.
Also, the number of needle-like items was 2 (pieces/0.1g) in the former, but none in the latter. In addition, when the oversized products generated by sizing were crushed and the undersized products were mixed with raw materials as they were and recycled, no change in the properties of the obtained granular Yorin was observed. Furthermore, the volatilization rate of ammonia gas produced by the reaction between Yorin and ammonium sulfate was 87% (in terms of ammonia) of the added ammonium sulfate. The granular yorin thus obtained has a slight decrease in fertilizing ingredients and a particle size of 2 m/m or less,
In addition, since the expression of water-soluble phosphoric acid is less than 1%,
In addition to fully satisfying the official standards for Yorin, it was lighter than those obtained by conventional methods, and was easy to remove without any flickering sensation. Example 2 Contains the same sandy yorin as in Example 1 and 0.28% by weight of ammonium chloride in terms of ammonium ion, and the respective concentrations are 8.3% by weight in terms of P ₂ O ₅ and 25% by weight in terms of SO ₃ Phosphoric acid and sulfuric acid each at 100Kg/hour and 12
The mixture was continuously fed to a pan-shaped granulator with an inner diameter of 1.5 m at a rate of 104 kg per hour after drying. The properties of the obtained granular yorin were as follows.

【table】

[Table] Next, the obtained granular Yorin was sized in the same manner as in Example 1, and the bulk specific gravity was 1.11 (g/cm ³ ).
A good granule containing no needles was obtained. In addition, the volatilization rate of ammonia gas at this time was 96%.
It was hot. Example 3 Contains the same sandy yorin as in Example 1 and 3.2% by weight of ammonium sulfate in terms of ammonium ion, SO ₃
Example 1 with a sulfuric acid solution having a concentration of 24.0% by weight at a rate of 100Kg/hour and 12.5Kg/hour, respectively.
When treated in the same manner as above, 106 kg of granular yorin with the following properties was obtained per hour.

【table】

[Table] Next, the obtained granular Yorin was sized in the same manner as in Example 1 to obtain a good granular material having a bulk specific gravity of 1.13 (g/cm ³ ) and containing no granules. . or,
When the crushing strength and powdering rate of the obtained granules were measured by a drop test, they were 1.1 to 1.6 kg/grain and
The content was 0.1 to 0.3%, which fully satisfied the requirements for granular products. Note that the volatilization rate of ammonia gas in this example was 35%. Example 4 Sand-like yorin similar to that used in Example 1 and a phosphoric acid solution containing 0.8% by weight of urea and having a concentration of 25% by weight in terms of P ₂ O ₅ were mixed at 100 kg/hour and 12 kg/hour, respectively.
The mixture was continuously fed into a mixer similar to that used in Example 1 at a rate of 103 kg/hour, and granulated and dried to obtain granular yorin having the following composition at a rate of 103 kg/hour.

[Table] Furthermore, the particle size distribution of this product was almost the same as that of Example 1. Furthermore, when the particles were sized using the same sieve as used in Example 1, the bulk specific gravity was 1.09 (g/cm ³ ).
It was hot. Comparative Example The same sandy yorin as in Example 1 and a phosphoric acid solution having a concentration of 20% by weight calculated as P ₂ O ₅ were treated in exactly the same proportions and equipment as in Example 1, and a granular yolk with the following properties was obtained. Phosphorus was obtained at a rate of 103 Kg/hour.

【table】

[Table] As is clear from this example, if ammonium ions are not added to the phosphoric acid solution, water-soluble P ₂ O ₅ and
The increase in MgO was remarkable, and when the water solubilization rate of P ₂ O ₅ was compared with that in Example 1, it was found that it increased by 66%. Next, the granular yorin obtained in this example was used in Example 1.
When the particles were sized in the same manner as in Example 1 and the bulk specific gravity was measured, it was 1.39 (g/cm ³ ), an increase of 18.8% compared to Example 1.
showed that.

Claims (1)

[Claims] 1. In a method for granulating fused phosphorous fertilizer by reacting fused phosphorous fertilizer with mineral acid, a mineral acid containing an ammonium compound is added to the fused phosphorous fertilizer in an acidic manner. A method for granulating fused phosphorus fertilizer, characterized in that it is used in an amount of 0.5 to 5% by weight in terms of anhydride. 2. The method according to claim 1, wherein the mineral acid is one or more acids selected from the group consisting of sulfuric acid, hydrochloric acid, nitric acid, and phosphoric acid. 3. The ammonium compound is one or more compounds selected from the group consisting of ammonium salts of inorganic acids, ammonium complex salts, and urea, and is used in an amount of 0.1 to 4% by weight in terms of ammonium ions (NH ₄ ⁺ ) in the mineral acid. A method according to claim 1 or 2.