JP2006021968A - Granular fertilizer and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a granular fertilizer having excellent disintegration in water at a low temperature and to provide its manufacturing method. <P>SOLUTION: The granular fertilizer contains a polyvinyl alcohol having a polymerization degree of 1,800 or less and a saponification degree of 90 mol% or less in an amount of not less than 1 pts. mass (in terms of a polyvinyl alcohol pure content) based on 100 pts. mass fertilizer powder being a raw material. The granular fertilizer is preferably one of a processed slag phosphate fertilizer, a slag silicate fertilizer, a mixed phosphate fertilizer and a compound fertilizer. The granular fertilizer can be manufactured by adding the polyvinyl alcohol having the polymerization degree of 1,800 or less and the saponification degree of 90 mol% or less in the amount of not less than 1 pts. mass based on 100 pts. mass crushed fertilizer raw material as an aqueous solution or together with water, and further adding and mixing if necessary a waste molasses liquid or a lignin sulfonate solution, and granulating and drying the mixture while spraying the water, the molasses liquid or the lignin sulfonate solution. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  TECHNICAL FIELD The present invention relates to a granular fertilizer and a method for producing the same, and more particularly to a granular fertilizer having good water disintegrability at low temperatures and a method for producing the same. Fertilizer here refers to a substance applied to the land for the purpose of providing nutrients to plants or bringing about chemical changes to the soil in order to contribute to the cultivation of plants, and is typically Article 3 of the Fertilizer Control Law. Among various fertilizers listed in the official fertilizer collection published by the National Fertilizer Quality Conservation Council, processed ore phosphophosphate fertilizer, mineral silicate fertilizer, mixed phosphate Fertilizer or chemical fertilizer. Granular fertilizer means the fine powder that has been granulated and dried to a particle size of 1 to 6 mm by adding a binder with a granulator.

  In the fertilizer field, granular products are generally less susceptible to wind when sprayed, so there is no dust generation, which is favorable for environmental conservation, suitable for machine spraying, and also has the property of collapsing in water or high moisture soils. Moreover, the form of fertilizer is rapidly shifting from the conventional sand form to granulation due to the fact that the fertilizer effect is larger than that of the sandy product. In the production of this granular product, a step of adding a granulation accelerator called a binder to the raw material powder, granulating it using a pelletizer or the like, and drying the resulting granulated raw pellet with a rotary dryer or the like is adopted. . In a conventional granulation method, a lignin sulfonate solution or a molasses solution is used as a binder. In general, the addition rate is about 3 to 8% in terms of the solid content of the binder with respect to the fertilizer powder as a raw material.

  However, when the binder by the above conventional granulation method is used, for example, to produce processed mineral phosphophosphate fertilizer, the processed mineral phosphophosphate fertilizer has a high water absorption capacity, so a very large amount of binder is required for granulation. It is uneconomical. Moreover, even if a considerable amount is used, sufficient grain strength required for handling and handling of granular fertilizer, for example, grain strength of 20 N / grain or more cannot be obtained.

  The reason for this is that, first, the reaction between phosphoric acid added as an elution accelerator and slag produces a soft substance that easily elutes the silicic acid content in the slag. There is to destroy from there. Secondly, the reaction between the slag and the elution promoter makes the entire slag porous, and the impregnation of the binder is approximately twice that of the raw slag, which may impede the function of the binder. . Further, these binders generally have a bad odor, and complaints are often received from private houses around the manufacturing plant, and there is a need for an odorless binder instead.

  In addition, when such a large amount of binder is used for granulation of processed ore phosphophosphate fertilizer, the effect on soil improvement as well as plant nutrition becomes insufficient due to a decrease in water disintegration. In addition, the use of a large amount of binder causes a problem of dilution of fertilizer components. Among these, as a means for improving underwater disintegration, Patent Document 1 discloses that an iron slag granular fertilizer containing steel slag and a binder contains an oxyalkylene ether compound having a specific structure in the fertilizer. ing. By the above means, improvement of the water disintegration property and soil disintegration property of the granular fertilizer can be expected.

  However, when granular fertilizer is sprayed in the snowy areas such as Hokkaido as a snow melting agent in early spring, it is not sufficient to satisfy the above water disintegration property and soil disintegration property, and it will collapse at low temperatures during the snow melting process. However, it is required to exert a snow melting effect.

  The underwater disintegration test method and the soil disintegration test method in the granular fertilizer test method are defined in Non-Patent Document 1. According to this, the disintegration property in water is evaluated based on the rate at which 50 granular fertilizers of 2 mm or more disintegrate 80% or more after standing overnight in water. On the other hand, for soil disintegration, 50 samples were embedded for 1 week in the soil (50 g of air-dried equivalent) with the same granular fertilizer used in the water disintegration test and water equivalent to 60% of the maximum water capacity. If 20 samples are taken out and the hardness is measured and the average is 1 N / grain or less, it is assumed that there is soil disintegration. Alternatively, evenly spread the entire amount of soil treated on a 2000 μm sieve, gently pour water at room temperature, and after standing overnight, count the number of undisintegrated remaining on the sieve and determine the remaining ratio. . However, the water temperature in these tests is not specified. Therefore, it is customary to test at room temperature (approximately 20-30 ° C).

Japanese Patent Laid-Open No. 11-157977 Manual for Fertilizer Registration, etc.-Overview of On-site Inspection-(March 1, 2001, edited and published by the Fertilizer Association Newspaper), page 128

  The present invention aims to solve the problems associated with such conventional granular fertilizers, and in particular for processed mineral silicic acid fertilizers, without using a lignin sulfonate solution or waste molasses, etc. An object of the present invention is to propose a granular fertilizer that can be surely granulated and does not cause dilution of fertilizer components and has excellent water disintegrability at low temperatures and a method for producing the same.

  As a result of extensive research and research on granulation binders related to granular fertilizers, especially processed mineral phosphophosphate fertilizers, the present inventors use polyvinyl alcohol having a specific degree of polymerization and saponification as the main granulation binder. As a result, it was found that a granular fertilizer excellent in water disintegration property at a low temperature was obtained, and the present invention was completed.

  The granular fertilizer according to the present invention contains polyvinyl alcohol having a polymerization degree of 1800 or less and a saponification degree of 90 mol% or less with respect to 100 parts by mass of the raw material fertilizer powder (in terms of pure polyvinyl alcohol) at a low temperature. Excellent in water disintegration. It is desirable that the granular fertilizer is any one of a processed mineral phosphophosphate fertilizer, a mineral silicate acid fertilizer, a mixed phosphate fertilizer, and a chemical fertilizer.

  The granular fertilizer is added as an aqueous solution or water together with 1 part by weight or more of polyvinyl alcohol having a polymerization degree of 1800 or less and a saponification degree of 90 mol% or less with respect to 100 parts by weight of the crushed fertilizer raw material. It can be produced by adding a molasses solution or lignin sulfonic acid solution and kneading, granulating while spraying water, waste molasses solution or lignin sulfonate solution, and drying.

  The present invention is widely applicable to granular fertilizers in general, and the composition is not particularly limited. Examples of fertilizer names to which the present invention can be applied include molten phosphate fertilizer, mixed phosphate fertilizer, calcite fertilizer, calcium carbonate fertilizer, mixed lime fertilizer, mineral silicate fertilizer, other siliceous fertilizers, hydroxylated Examples include mafic fertilizers, by-acid bacilli fertilizers, processed mafic fertilizers, slag manganese fertilizers, and soluble trace element fertilizers. In addition to these, it can be applied to processed mineral silicate fertilizers for the purpose of silicic acid supply and pH correction with alkali as well as mineral silicate fertilizers and chemical fertilizers that require immediate effect. The present invention is particularly preferably applied to processed ore silicate fertilizer, mineral silicate fertilizer, mixed phosphate fertilizer, and chemical fertilizer. These granular fertilizers are pulverized to a mean particle size of 0.1 mm or less, mixed with a binder, kneaded, granulated by a granulator, and dried to form granular fertilizers.

  In the present invention, polyvinyl alcohol, particularly polyvinyl alcohol having a polymerization degree of 1800 or less and a saponification degree of 90 mol% or less is mainly used as the binder. The reason why the degree of polymerization is 1800 or less is that when the polymerization degree is exceeded, the disintegration in water at 0 ° C. decreases, and the net residual rate at 0 ° C. increases (see Example 2). If the degree of polymerization is too low, sufficient grain strength may not be obtained, but in the case of generally commercially available polyvinyl alcohol, the lower limit of the degree of polymerization is about 300, A granular fertilizer with no practical problems can be obtained. On the other hand, the reason why the degree of saponification is 90 mol% or less is that when the degree of saponification exceeds 90 mol%, only those having low grain strength can be obtained (see Example 1). In general, the lower limit of the saponification degree of commercially available polyvinyl alcohol is about 70 mol%, and such a thing can also be used for the present invention.

  Polyvinyl alcohol having these properties is added to the fertilizer raw material pulverized as an aqueous solution or as a powder. When adding as a powder, add the required amount of water to the crushed fertilizer raw material in a wet state in advance, or after adding or mixing powdered polyvinyl alcohol to the pulverized fertilizer raw material or mixing them. While adding water, make it granulated.

  What is necessary is just to let the addition amount of polyvinyl alcohol be 1 mass part or more with respect to 100 mass parts of pulverized fertilizer raw materials. If the addition amount is less than 1 part by mass, the grain strength required as a granular fertilizer cannot be obtained. There is no need to limit the amount of addition. However, the reinforcing effect by polyvinyl alcohol is about 3 parts by mass with respect to 100 parts by mass of the fertilizer raw material, and more than that is only a factor for increasing the cost, so generally 1-3 parts by mass It is good.

  As the binder added before granulation, polyvinyl alcohol alone is sufficient, but a small amount of molasses liquid or lignin sulfonate solution can be used together. Thereby, the further grain strength improvement effect is acquired. In the present invention, it does not prevent the use of the molasses liquid or lignin sulfonate solution as such an auxiliary binder, but the amount used is preferably 3% or less in terms of solids in terms of cost. .

  The powder fertilizer mixed with the binder is then subjected to a granulation step. This granulation step is generally performed using a dish type granulator while spraying water, molasses liquid or lignin sulfonate solution. As a result, the powder raw material particles put into the granulator are associated with the sprayed liquid to form loose agglomerates, which are tightened by the rolling operation of the granulator so that there are few voids between the particles. It becomes. Such a granulation action occurs even when water is used, but the use of a more viscous waste molasses solution or lignin sulfonate solution is more effective, and the grain growth becomes faster. What is necessary is just to determine the quantity of the water sprayed in the case of this granulation by the wet condition of the grain surface. When a relatively large amount of moisture is added, the grains become large, and when the amount of moisture is small, the grains become small and the amount of powder increases. Therefore, the amount of moisture is adjusted according to the granulation situation.

  The granulated fertilizer is dried by a shelf dryer, a fluid dryer, a rotary kiln or the like. For example, when a shelf-type dryer is used, a product is obtained by spreading thinly and uniformly on a drying shelf and drying at 100 ° C. for about 30 minutes.

  2 parts by mass of polyvinyl alcohol (PVA) powder with a polymerization degree of 500 and different saponification degree is added to 100 parts by mass of processed mineral phosphophosphate fertilizer powder. After mixing, 10 parts by mass of water was added, and after mixing, the mixture was transferred to a mini-plate granulator with a diameter of 240 mm and granulated by spraying 2 parts by mass of water. The obtained granulated material was dried with a shelf dryer maintained at 100 ° C., and then the particle strength and disintegration property in water were measured.

The characteristic value of the product was measured as follows.
(Grain strength) The obtained granulated material is sieved with a 3.35 to 4.0 mm standard sieve, and the grains remaining on the 3.35 mm sieve are used as test samples. Place one test sample on a plate of a spring-type table with a maximum weight of 70 N, press the cut end with a hard round bar with a flat end face with a diameter of about 10 mm, and read the indicated value N when the grain breaks The average value of the 10 pieces is taken as the grain strength (N / grain) of the product.
(Residual rate on net at 0 ° C. and disintegration in water at 0 ° C.) The granulated product is sieved with 2 mm and 4 mm standard sieves, and the 2 mm sieve is used as a test sample. Place 30 test samples on a 2 mm mesh and place them in a vat, and gently pour water that has been cooled to 0 ° C. in a refrigerator in advance so that the sample is sufficiently immersed in water. This is allowed to stand overnight in a refrigerator maintained at 0 ° C., and then the ratio of the grains with the grain prototype retained on the sieve is measured to obtain the residual ratio on the net. On the other hand, the 0 ° C water disintegration is the sum of the ones that did not retain the grain shape on the sieve when measuring the 0 ° C net residual rate and the ones that were picked up and collapsed with the tweezers when the 0 ° C net residual rate was measured. Obtained by the ratio (percentage) of the finished grains.

  The measurement results are shown in Table 1. From this result, it can be seen that a granulated product having a high grain strength is obtained in the range of 90 mol% or less of the saponification degree, but the grain strength becomes low when the saponification degree is 98 to 99 mol%.

  Processed slag phosphate fertilizer powder pulverized to a particle size suitable for granulation, saponification degree 83-86 mol%, polyvinyl alcohol (PVA) powder with different polymerization degree is 2 parts per 100 parts by weight of processed slag phosphate fertilizer powder. After adding and mixing parts by mass, the mixture was transferred to a mini bread granulator having a diameter of 240 mm and granulated by spraying water. The obtained granulated product was dried with a shelf dryer maintained at 100 ° C., and then the particle strength and disintegration property in water were measured in the same manner as in Example 1. The measurement results are shown in Table 2. From this result, it can be seen that the particle strength increases as the degree of polymerization of polyvinyl alcohol increases, but when the degree of polymerization exceeds 1800, the disintegration in water deteriorates and the residual ratio on the net also increases.

  Polyvinyl alcohol powder having a polymerization degree of 500 and a saponification degree of 83 to 86 mol% is added as a binder to 100 parts by mass of a processed mineral phosphophosphate fertilizer powder pulverized to a particle size suitable for granulation, and water is further added to 10.0 parts. After adding a mass part and mixing, it granulated by the size of 1-6 mm, spraying the waste molasses with a solid content of 20 mass% with the dish type granulator of diameter 600mm. The amount of waste molasses used for granulation was 10-12 parts by mass with respect to the processed mineral phosphophosphate fertilizer powder. The granulated product was dried with a shelf dryer at 100 ° C. to obtain a product, and its characteristic value was measured. The results are shown in Table 3. Grain strength increased as the amount of polyvinyl alcohol added increased. The granulated product was sufficiently satisfied with the net residual rate at 0 ° C. and the disintegration in water of 100% regardless of the addition rate of polyvinyl alcohol.

  Polyvinyl alcohol (PVA) aqueous solution (concentration 20% by mass) with a polymerization degree of 500 and a saponification degree of 83 to 86 mol% is converted into polyvinyl alcohol (PVA) addition amount to the processed mineral phosphophosphate fertilizer powder pulverized to a particle size suitable for granulation Then, after adding and mixing so as to be 2% by mass, the mixture was transferred to a mini dish granulator having a diameter of 240 mm, and granulated by spraying 2 parts by mass of water. The obtained granulated product was dried in the same manner as in Example 1, and then the particle strength and disintegration property in water were measured. The characteristic values of the obtained product were: grain strength: 15 (N / grain), 0 ° C water disintegration 100%, 0 ° C net residual rate 0%.

  Polyvinyl alcohol aqueous solution with a polymerization degree of 500 and a saponification degree of 83-86 mol% (concentration 20 mass%) is converted to 2 mass% in terms of polyvinyl alcohol addition amount to the processed mineral phosphophosphate fertilizer powder ground to a particle size suitable for granulation. After adding and mixing, the mixture was transferred to a mini dish granulator with a diameter of 240 mm, and granulated by spraying a molasses liquid with a solid content of 20% by mass. The amount of molasses liquid added was 2% by mass in terms of solid content. Next, the obtained granulated product was dried in the same manner as in Example 1, and then the particle strength and disintegration property in water were measured. The characteristic values of the obtained product were: grain strength: 17 (N / grain), 0 ° C water disintegration 100%, and 0 ° C net residual rate 0%.

  After adding 2.0 parts by mass of polyvinyl alcohol powder as a binder to 10 parts by mass of processed mineral phosphophosphate fertilizer powder ground to a particle size suitable for granulation, add 10 parts by mass of water, mix, 1-6mm size while spraying Sun Extract M solution (solid content 20% by mass), which is a lignin sulfonic acid solution, to 2.6 parts by mass in terms of solid content on processed mineral silica phosphate fertilizer powder with a granulator Granulated and dried. The obtained product had an average grain strength of 24 N / grain, a net residual rate at 0 ° C. of 0%, and an underwater disintegration of 100%.

  100 parts by weight of powdered fertilizer having a composition of 12.4% by weight of urea, 61.1% by weight of ammonium sulfate, 5.7% by weight of ammonium phosphate, 11.4% by weight of lime perphosphate, and 9.4% by weight of potassium chloride. After adding 2 parts by mass of polyvinyl alcohol powder having a degree of conversion of 83 to 86 mol% and further mixing 8 parts by mass of water, the molasses liquid becomes 2.5 parts by mass in terms of solid content with respect to 100 parts by mass of powdered chemical fertilizer. While spraying, the mixture was granulated to a size of 1 to 6 mm with a dish type granulator having a diameter of 240 mm. The obtained granulated product was dried with a box dryer at 100 ° C., and then product characteristics were measured in the same manner as in Example 1. The resulting product had a grain strength of 30 N / grain, a net residual rate at 0 ° C. of 0%, and a water disintegration of 100%.

  2 parts by mass of polyvinyl alcohol powder having a polymerization degree of 500 and a saponification degree of 83 to 86 mol% as a binder is added to 100 parts by mass of mineral silicate acid fertilizer powder ground to a particle size suitable for granulation, and further 8 parts by mass of water. In addition, after mixing, it was granulated to a size of 1 to 6 mm while spraying water with a dish type granulator having a diameter of 240 mm to 8% with respect to 100 parts by mass of the mineral fertilizer powder. The obtained granulated product was dried with a box dryer at 100 ° C., and then product characteristics were measured in the same manner as in Example 1. The obtained product had a grain strength of 28 N / grain, a net residual rate at 0 ° C. of 0%, and a water disintegration of 100%.

  As a binder, 100 parts by weight of raw material for mixed phosphate fertilizer (mixture of 63% by weight of mineral fertilizer, 21% by weight of molten fertilizer, 16% by weight of iron ore) is pulverized to a particle size suitable for granulation. Add 2 parts by weight of polyvinyl alcohol powder with a polymerization degree of 500 and a saponification degree of 83-86 mol%, add 10 parts by weight of water, mix, and then add waste molasses (solid content 20% by weight) to 100% phosphate fertilizer It was granulated to a size of 1 to 6 mm with a dish type granulator having a diameter of 240 mm while spraying to 2 parts by mass in terms of solid content with respect to mass parts. The obtained granulated product was dried with a box dryer at 100 ° C., and then product characteristics were measured in the same manner as in Example 1. The obtained product had a grain strength of 60 N / grain, a net residual rate at 0 ° C. of 0%, and a water disintegrability of 100%.

As can be understood from each of the above examples, the granular fertilizer granulated using polyvinyl alcohol having a polymerization degree of 1800 or less and a saponification degree of 90 mol% or less as in the present invention has a high product grain strength and is on a net at 0 ° C. It has a low residual rate and a high level of underwater disintegration, and is extremely excellent as a granular fertilizer that is sprayed as a snow melting agent in early spring in snowy areas. In addition, this invention is not limited to the said Example, unless it deviates from the technical idea of this invention, Of course, it can implement with a various form.

Claims (3)

  A granular fertilizer containing 1 part by mass or more (in terms of pure polyvinyl alcohol) of polyvinyl alcohol having a polymerization degree of 1800 or less and a saponification degree of 90 mol% or less with respect to 100 parts by mass of the raw material fertilizer powder.   The granular fertilizer according to claim 1, wherein the granular fertilizer is any one of a processed ore phosphosilicate fertilizer, a mineral silicate fertilizer, a mixed phosphate fertilizer, and a chemical fertilizer. One part or more of polyvinyl alcohol having a polymerization degree of 1800 or less and a saponification degree of 90 mol% or less is added as an aqueous solution or with water to 100 parts by mass of the crushed fertilizer raw material. A method for producing a granular fertilizer, characterized by adding a solution, kneading, granulating water and waste molasses while spraying a lignin sulfonate solution, and drying.