JP-7854689-B2 - Fertilizer and its manufacturing method

Inventors

• 井上 春美
• 橋本 直也
• 西本 剛
• 森泉 美穂子
• 阿江 教治

Assignees

• 三洋化成工業株式会社
• 学校法人 龍谷大学

Dates

Publication Date

20260507

Application Date

20240828

Priority Date

20230829

Claims (5)

1. A substance containing a poorly soluble phosphate, a polymer compound having a carboxyl group and/or a carboxylic acid base in its molecule , and water . With respect to 100 parts by weight of the substance containing the sparingly soluble phosphate, the amount of the polymer compound having a carboxyl group and/or a carboxylic acid base in its molecule is 0.1 to 100 parts by weight, and the amount of water is 1,000 to 30,000 parts by weight. A fertilizer in which the total amount of carboxyl groups and carboxylic acid bases contained in the polymer compound having a carboxyl group and/or a carboxylic acid base in its molecule is 5 mmol/g or more.
2. The fertilizer according to claim 1, wherein the polymer compound having a carboxyl group and/or a carboxylic acid base in its molecule is a polymer containing constituent units derived from (meth)acrylic acid and/or (meth)acrylate salt.
3. Step 1 involves mixing a substance containing a poorly soluble phosphate, a polymer compound having a carboxyl group and/or a carboxylic acid base in its molecule , and water . In step 1, the amount of the polymer compound having a carboxyl group and/or a carboxylic acid base in its molecule is 0.1 to 100 parts by weight per 100 parts by weight of the substance containing the sparingly soluble phosphate. In step 1, 100 to 30,000 parts by weight of water are mixed with 100 parts by weight of a substance containing a sparingly soluble phosphate. A method for producing fertilizer, wherein the total amount of carboxyl groups and carboxylic acid bases contained in the polymer compound having a carboxyl group and/or a carboxylic acid base in its molecule is 5 mmol/g or more.
4. The method for producing fertilizer according to claim 3, wherein the polymer compound having a carboxyl group and/or a carboxylic acid base in its molecule is a polymer containing constituent units derived from (meth)acrylic acid and/or (meth)acrylate salt.
5. The method for producing fertilizer according to claim 4, further comprising the step of allowing the mixture obtained by mixing with water in step 1 to stand at a temperature of 10°C to 80°C.

Description

This invention relates to fertilizer and a method for producing the same. Phosphorus, along with nitrogen and potassium, is an essential nutrient for plant growth, and its supply is often achieved by applying chemical fertilizers to farmland. In recent years, from the perspective of reducing environmental impact and economically producing phosphorus fertilizer, there has been research into recovering water-soluble phosphorus from waste materials such as sludge incineration ash, sludge, soil (including industrial waste soil and horticultural waste soil), steelmaking slag, livestock manure, and food waste, and using it as fertilizer. Conventional techniques for recovering phosphoric acid sometimes require a step to make the pH of the material being treated acidic or alkaline (see [0003] of Patent Document 1). The equipment used in such a step is prone to corrosion, and methods including such a step raise concerns about the safety of personnel involved in phosphoric acid recovery operations. Furthermore, since treated materials whose pH has become acidic or alkaline cannot be released into the environment in their current state, a process to neutralize the pH of the treated materials is also necessary. Therefore, improvements in simplification are needed in the technology for recovering phosphoric acid, and these are being investigated (see Patent Document 1). Patent No. 5664995 <Fertilizer> The fertilizer of the present invention comprises a substance containing a poorly soluble phosphate and a polymer compound having a carboxyl group and/or a carboxylic acid base in its molecule, wherein the total amount of carboxyl groups and carboxylic acid bases contained in the polymer compound having a carboxyl group and/or a carboxylic acid base in its molecule is 5 mmol/g or more. In this specification, carboxyl groups and/or carboxylic acid bases are also referred to as "carboxylic acid (salt) groups." In this invention, the substance containing sparingly soluble phosphate is not particularly limited as long as it contains sparingly soluble phosphate. Examples of substances containing sparingly soluble phosphate include phosphate compounds such as aluminum phosphate, iron(III) phosphate dihydrate, and tricalcium phosphate; and resources such as soil, rice bran, rice husks, rice husk char, livestock manure (cow manure, pig manure, chicken manure), livestock manure char, sludge, sludge incineration ash, steelmaking slag, and food waste. In this invention, "poorly soluble phosphate" means "all phosphates other than water-soluble phosphates." In this invention, "water-soluble phosphate" means "phosphate dissolved in water at 25°C." In this invention, "dissolved in water at 25°C" means "dissolves 0.1 mg or more in 1000 g of water at 25°C." In the present invention, the polymer compound having a carboxylic acid (salt) group in its molecule has a total amount of carboxyl group and carboxylic acid base of 5 mmol/g or more. The total amount of carboxyl group and carboxylic acid base in the compound is 5 mmol/g or more, which allows for sufficient solubilization of sparingly soluble phosphates in substances containing sparingly soluble phosphates. Even with polymer compounds having a carboxylic acid (salt) group, if a compound with a total amount of carboxyl group and carboxylic acid base of less than 5 mmol/g is used, the solubilization of sparingly soluble phosphates in substances containing sparingly soluble phosphates will not be sufficiently exhibited. From the viewpoint of being excellent in solubilizing sparingly soluble phosphates in substances containing sparingly soluble phosphates, polymer compounds having a carboxylic acid (salt) group in the molecule are preferably those in which the total amount of carboxyl groups and carboxylic acid bases is 9 mmol/g or more, and more preferably those in which it is 10 mmol/g or more. The amount of carboxylic acid (salt) groups in a polymer compound containing a carboxylic acid (salt) within its molecule can be determined by the following method. (1) Place the sample in a beaker, weigh it accurately (1 g), add 50 ml of deionized water and stir to dissolve or swell the sample and obtain the sample solution. (2) Immerse the electrode of the potentiometric titrator in the sample solution and, while stirring, add a mixture of reagent primary hydrochloric acid (35%) and ion-exchanged water (35% hydrochloric acid:ion-exchanged water = 1:1) dropwise until the pH of the sample solution is 3 or less. (3) Add 0.1 mol/L potassium hydroxide methanol standard solution little by little, stirring until the potential difference becomes constant, and record the potential difference and the amount added when the potential difference becomes constant. Repeat this procedure until the endpoint is reached. The endpoint is determined by plotting the volume of standard solution added and the potential difference on graph paper, and marking the inflection point of the titration curve as the endpoint of