JPH0474313B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a granulating agent for fertilizers, and more specifically, to a granulating agent for fertilizers comprising a sizing liquid obtained by gelatinizing starch under specific conditions. [Conventional technology] Most fertilizers are generally in the form of powder or sand (both are referred to as powder), and conventionally, they have been used by spraying them on the soil in powder form. . However, in recent years, as mechanical spreading has become commonplace, it has become necessary to granulate powdered fertilizer from the standpoint of adaptability to spreading machines and prevention of scattering during spreading. This is becoming more and more common. To granulate powdered fertilizer, mix the powdered fertilizer with water or an appropriate granulating agent, and then
It is common to use a pan- or drum-shaped granulator to form granules, which are then dried to form a granular product. Granulated fertilizer needs to be strong enough to withstand destruction so that it will not break or turn into powder when force is applied to the granules during transportation or when mixing fertilizers. Moreover, its strength does not decrease over time,
It is required that the compressive fracture strength of one grain be maintained at 1 to 2 kg, preferably 3 kg or more. Fertilizers granulated using only water have weak bonding strength between powdered fertilizers, resulting in almost no strength of the granules, and it is often necessary to select and use an appropriate granulating agent. Furthermore, while granular fertilizers are required to maintain strength, they are also required to have appropriate disintegrability, that is, the granules must quickly break and disperse after being spread. Normally, fertilizers that have been granulated by adding a granulating agent have higher fracture resistance, but tend to have lower disintegration properties during use. Thus, there is a need to produce granular fertilizers that have the contradictory properties of fracture resistance and appropriate disintegration, but a granulating agent that satisfies both properties has not yet been found. is the current situation. As a specific measure of disintegration, there is an underwater disintegration test in which completed granular fertilizer is thrown into water and the number of disintegrated granules is determined. (Note that in the following description, disintegration in water may be simply abbreviated as disintegration.) In addition to the above characteristics, the granulating agent should be effective when added in as little amount as possible. Therefore, it is desirable that the solid content is 1% by weight or less of the fertilizer. This is because if the amount of granulating agent added increases, the content of a predetermined active ingredient in the fertilizer will decrease relatively, and there is a possibility that the specified amount may not be maintained. In addition, necessary conditions include that the granulating agent is inexpensive and that the granulation cost is economically viable even when the fertilizer is granulated. Currently, granulating agents for fertilizers that are generally used or that can be used can be roughly divided into organic wastes such as alcohol waste liquid, molasses, and pulp waste liquid, and polyvinyl alcohol (hereinafter referred to as polyvinyl alcohol). ), carboxymethyl cellulose (sometimes abbreviated as CMC in the following descriptions),
There are polymeric substances such as sodium alginate. When using the former organic waste, the amount added is 3 to 10% by weight of the solid content of the fertilizer.
The problem is that a relatively large amount is required, which affects the active ingredients of the fertilizer. Furthermore, depending on the type of fertilizer, the grains of some fertilizers absorb moisture and their strength decreases dramatically when left in the atmosphere. In addition, many of these wastes have strong odors, and furthermore, many of them have problems such as not being stably supplied as raw materials. The latter polymeric material is generally expensive, and its unit price is 10 to 100 times higher than the former.
Therefore, when this is used as a granulating agent in an amount necessary to maintain the strength of the granules, the granulation cost becomes extremely high, and in many cases it cannot be put into practical use economically. In addition, there are some materials that show excellent performance in terms of strength but have poor disintegration properties. [Problems to be Solved by the Invention] As mentioned above, conventionally, when granulating fertilizer, granular fertilizer with excellent strength and disintegration properties was given,
At present, it is difficult to find a granulating agent that can produce granules with a small amount of addition. An object of the present invention is to provide a granulating agent that, when used as a granulating agent for fertilizers, imparts strength and appropriate disintegrability, is effective with a small amount added, and is inexpensive. As a result of intensive research, the present inventors discovered that a sizing liquid obtained by gelatinizing starch with an alkali under specific conditions can be used as a high-performance and inexpensive granulating agent for fertilizers, and based on this knowledge, the present invention was developed. It was about to be completed. [Means for Solving the Problem] That is, the gist of the present invention is to gelatinize starch by adding 8 to 60 parts by weight of alkali to 100 parts by weight of solid content of starch in the presence of water. It is a granulating agent for fertilizers made of paste liquid. Further, the present invention provides a granular fertilizer granulated using the above-mentioned granulating agent. Hereinafter, the constituent elements of the present invention will be explained in detail. (Starch and its gelatinization) Various starches can be used in the present invention, including ground starch such as corn starch, rice starch, and wheat starch, and underground starch such as potato starch and tapioca starch. During gelatinization, an alkali is added to an aqueous starch suspension with a starch concentration of 5 to 20% by weight, and the amount of alkali added depends on the solid content of the starch.
A range of 8 to 60 parts by weight per 100 parts by weight is preferable.
After addition of the alkali, gelatinization is carried out at a temperature of about 20°C to about 100°C, with a preferred temperature range of 40°C to 80°C. Examples of the alkali include caustic soda (sodium hydroxide) and caustic potash (potassium hydroxide). The most appropriate amount of alkali to be added is within the above range. If the amount is smaller than this, the strength of the grains can be maintained, but the disintegration property will be lost. on the other hand,
Those containing more alkali than this have good disintegration properties, but the strength of the particles decreases over time. Starch is insoluble in water at room temperature, but when heated, its crystal structure (micelle) is destroyed, gelatinized (ie, gelatinized), and dissolved in water. Gelatinized starch solutions are generally used as adhesives and adhesives, but when conventional starch solutions are used as granulating agents for powdered fertilizers, it takes a long time to obtain sufficient strength as a granulated product. Addition of granulating agents significantly reduces the disintegration properties of granular fertilizers. The present inventors added a certain amount of alkali to an aqueous suspension of starch to gelatinize the starch, and used the resulting sizing liquid as a granulating agent to increase the strength of the resulting granular fertilizer. We succeeded in achieving extremely good disintegration properties while maintaining the same level of disintegration. The starch solution produced under the conditions of the present invention has extremely excellent properties as a granulating agent for fertilizers.
In other words, the strength of granules obtained by adding 0.3% to 0.7% starch as solid content in the solution to the fertilizer to be granulated changes little over time, has an average strength of 1 kg to 3 kg, and does not disintegrate. They are also extremely good at sex. The effect that this starch solution has on the grains is due to the adhesive strength of the gelatinized starch.
It is thought that by binding the fertilizer particles together, the strength of the particles is maintained during drying, and that when the particles are thrown into water, their disintegration is promoted by the action of the added alkali. (Fertilizer) Fertilizers that can be produced into extremely high-quality granules using the granulating agent of the present invention may be any of mineral fertilizers, mineral fertilizers, glass fertilizers, and the like. In particular, fused phosphorus fertilizer, by-product lime, which needs to be disintegrable in water,
Calcium carbonate fertilizer, mixed lime fertilizer, mineral silicic acid fertilizer, other silicic acid fertilizer, hydroxide magnesium fertilizer,
For by-product basic magnesium soil fertilizer, processed magnesium soil fertilizer, slag manganese fertilizer, molten trace element compound fertilizer, etc.
The granulating agent of the present invention can be well applied. EXAMPLES In order to make the present invention easier to understand, examples will be described below, but the following examples do not limit the present invention in any way. Example 1 (1) Production of granulating agent A case will be described in which corn starch, tapioca starch, and potato starch are used as starch. Water for 7.7 parts by weight of each starch
After adding 90.5 parts by weight and stirring to suspend, the temperature was gradually raised to 80°C. Then add 2.0 parts by weight to 2.8 parts by weight of 48% caustic soda solution.
Add within the weight range and continue stirring for 30 minutes while heating. Thereafter, it was cooled and used as a granulating agent. (2) Fertilizer granulation Add a predetermined amount of granulation agent to the molten phosphorus fertilizer adjusted to the predetermined particle size in a solid content ratio, then add an appropriate amount of water, mix well, and then Granulation was performed using a mold granulator. After drying the resulting grains at 105℃ for 12 hours, they were classified using a 4 mm sieve and a 1 mm sieve, and those with a size of 1 mm to 4 mm were subjected to a grain strength test and a water disintegration test. provided. (3) Strength test Five grains of the test product were taken and the strength was measured using a Kiya type hardness tester. The strength was measured immediately after drying, and in order to understand the change in strength over time, the grains of the test product were left in an atmosphere with a temperature of 20°C and a humidity of 65%, and were measured after 5 hours, 24 hours, and 48 hours. It was measured. (4) Underwater disintegration test Fifty grains of the test product were thrown into water, left to stand for 12 hours, and then gently pulled out to count the number of grains that had not disintegrated. If this number is 10 or less, ○,
Items that have not completely collapsed are shown as ×, and items in between are shown as △.

[Table] According to this table, regardless of the type of starch, the fused phosphorus fertilizer granulated using the granulating agent according to the method of the present invention shows a strength of 3 kg or more even after 48 hours, and It also has excellent disintegration properties. Example 2 (1) Production of granulating agent 90.5 parts by weight of water is added to 7.7 parts by weight of corn starch, stirred to suspend, and then gradually heated to 80°C. Then, add 1.2 parts by weight of 48% caustic soda solution, and keep heating for 30 minutes.
Continue stirring. Thereafter, the mixture was cooled and used as a granulating agent. Furthermore, for comparison, blackstrap molasses, alcohol waste liquid, KP lignin, SP lignin, PVA A;
Partially saponified PVA, PVA Otsu; Completely saponified PVA,
Sodium alginate, CMC, etc. were also used as granulating agents in the following tests. (2) Fertilizer granulation The granulation was carried out in the same manner as in Example 1 using each of the granulating agents in (1) above for fused phosphorus fertilizer prepared to a predetermined particle size. (3) Strength test and underwater disintegration test In the same manner as in Example 1, a grain strength test and an underwater disintegration test were conducted. The results of the test are shown in Table 2.

【table】

[Table] As shown in Table 2, even if starch (corn starch) is used, a granulating agent with a lower amount of alkali than the method of the present invention has inferior disintegration properties. For materials other than starch, 3 kg even after 48 hours.
Sodium alginate is the only material that exhibits the strength above, has excellent disintegration properties, and has an added amount of 1% or less. Alcohol waste liquid and SP waste liquid have high strength when the amount added is 3%, but when the amount added is lowered to 1%, the strength can no longer be maintained. Furthermore, since sodium alginate is approximately 20 times more expensive than starch, it can be said that the superiority of the granulating agent of the present invention is clear from a comprehensive evaluation including economic efficiency. Example 3 (1) Production of granulating agent 87 parts by weight of water was added to 7.7 parts by weight of cornstarch, stirred to suspend, and then gradually heated to 70°C. Then, 48% caustic soda is added in a range of 5.5 parts by weight to 7.0 parts by weight,
Stirring was continued for 30 minutes while heating. Thereafter, this was cooled to obtain a granulating agent. (2) Fertilizer granulation Calcium silicate is ground to a specified particle size, and the
Granulation was carried out in the same manner as in Example 1 using the granulating agent obtained by method (1). (3) Strength test and underwater disintegration test In the same manner as in Example 1, a grain strength test and an underwater disintegration test were conducted. However, the strength of the grains was measured only immediately after drying and after 24 hours. For comparison purposes, similar tests were conducted using KP waste liquid and blackstrap molasses. The test results are shown in Table 3.

[Table] As is clear from Table 3, all of the samples had good disintegration properties in water, but when comparing the strength after 24 hours, it is clear that the granulating agent of the present invention is superior. Example 4 (1) Production of granulating agent Add 87 parts by weight of water to 7.7 parts by weight of cornstarch and stir to make a suspension. While keeping this at 40°C, add 9.0 parts by weight of 48% caustic soda, and then stir for 2 hours. After continued stirring, the mixture was cooled and used as a granulating agent. (2) Fertilizer granulation Lightly calcined magnesium and magnesium calcium carbonate pulverized to a predetermined particle size were mixed at a ratio of 4:6 by weight, and granulated in the same manner as in Example 1. (3) Strength test and underwater disintegration test A grain strength test and an underwater disintegration test were conducted in the same manner as in Example 3. In addition, for comparison purposes, a similar test was conducted using KP waste liquid. The results are shown in Table 4.

[Table] Here again, the starch granulating agent of the present invention obtained higher strength with a smaller amount added than the KP waste liquid, and its superiority is clear. Example 5 (1) Production of granulating agent A starch granulating agent was produced in the same manner as in Example 1. (2) Fertilizer granulation Granulation was performed in the same manner as in Example 1 using calcium carbonate powder pulverized to a predetermined particle size. (3) Strength test and underwater disintegration test A grain strength test and an underwater disintegration test were conducted in the same manner as in Example 3. In this test as well, KP waste liquid was used for comparison. The results are shown in Table 5.

[Table] As is clear from Table 5, the granulating agent of the present invention exhibits excellent properties even when used for calcium carbonate. Comparative Example Manufacturing method of granulating agent 92.3 parts by weight of water was added to 7.7 parts by weight of corn starch, and gelatinized at 60°C for 30 minutes while stirring. The results are shown in Table 6.

[Table] Example 6 (1) Production of granulating agent Starch-1 Add 90.5 parts by weight of water to 7.7 parts by weight of cornstarch, stir to suspend, and then gradually heat while stirring to raise the temperature to 80°C. do. Then, 2.5 parts by weight of a 34% concentration caustic potash solution was added,
Continue stirring for 30 minutes while heating. Thereafter, it is cooled and used as a granulating agent. Starch-2: Made using the same method as Starch-1, with the amount of caustic potash added to 3.5 parts by weight. Starch-3: Made using the same method as Starch-1, with the amount of caustic potassium being 8.75 parts by weight. (2) Granulation of Fertilizer Molten phosphorus fertilizer was granulated in the same manner as in Example 1 using the three types of granulation agents described in (1). (3) Strength test and underwater disintegration test In the same manner as in Example 3, a grain strength test and an underwater disintegration test were conducted. The results are shown in Table 7.

[Table] [Effects of the Invention] The granulating agent of the present invention made it possible to economically produce granular fertilizer with excellent properties with a small amount added. Fertilizer particles granulated using the granulating agent of the present invention are excellent in both strength and disintegration, and the amount of granulating agent added is extremely small at 1% or less.
It also has little effect on fertilizer components. Moreover, by changing the manufacturing conditions, it is possible to adapt to all kinds of fertilizers. The fact that such a granulating agent can be produced at an extremely low cost is truly revolutionary and will have a major impact on fertilizer granulation technology.

Claims (1)

[Scope of Claims] 1. A granulating agent for fertilizers consisting of a gelatinizing solution in which starch is gelatinized by adding 8 to 60 parts by weight of alkali to 100 parts by weight of solid starch in the presence of water. 2. Granular fertilizer granulated using the granulating agent for fertilizer according to claim 1. 3. The granular fertilizer according to claim 2, wherein the granulated fertilizer is a powdered mineral fertilizer, slag fertilizer, or glassy fertilizer.