JPH021797B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a new chemical fertilizer containing potassium silicate lime as a main component. In recent years, pollution prevention and resource conservation have become major issues in industry, and there has been widespread interest in the effective use of industrial waste and industrial by-products. For example, coal ash (fly ash) discarded from lime-fired power plants, metal smelting slag, metal silicon,
It is important to effectively utilize silicon dust generated during the production of ferrosilicon and the like. On the other hand, in the field of agriculture, slow-release fertilizers have many advantages such as no concentration disturbance, high utilization rate of fertilizer components, less leaching and runoff, and saving fertilizer resources. -Oxo-4-methyl-6-ureidohexahydropyrimidine, isobutylidene urea, etc. Phosphate fertilizers include heavy calcined phosphorus and dissolved phosphorus fertilizers, and potash fertilizers have recently been developed by one of the inventors of the present invention. The resulting potassium silicate has come to be used as a slow-release potassium fertilizer. This potassium silicate has many advantages as a slow-release fertilizer mentioned above, but it requires high-temperature calcination during production, resulting in high fuel consumption, relatively low fertilizer content, and high alkalinity. Therefore, when mixed with nitrogen fertilizers such as ammonium sulfate, ammonium phosphate, urea, etc., ammonia is volatilized, resulting in limitations in terms of use. The present inventors conducted extensive research to solve these problems, and as a result, they came up with the invention of a new slow-release chemical fertilizer containing phosphoric acid and potassium, and a method for producing the same. The novel chemical fertilizer of the present invention is produced by mixing a silicic acid-containing material made of industrial waste and/or a natural product, or the silicic acid-containing material and phosphate rock with phosphoric acid or a mixed acid of phosphoric acid and sulfuric acid, and then It is characterized by containing potassium silicophosphate as a main component, which is obtained by adding element-containing substances and causing a ripening reaction, and then adding a basic potassium compound and firing. The novel method for producing a chemical fertilizer of the present invention includes mixing a silicic acid-containing material made of industrial waste and/or a natural product, or the silicic acid-containing material and phosphate rock with phosphoric acid or a mixed acid of phosphoric acid and sulfuric acid, It is characterized in that, after adding necessary trace element-containing substances and causing an aging reaction, a basic potassium compound and preferably an exothermic reaction accelerator are added, mixed, and fired. The potassium silicate lime referred to in the present invention is a reaction product of silicic acid, phosphoric acid, calcium phosphate, and basic potassium compound contained in the silicic acid-containing material, phosphate rock, and phosphoric acid solution basic potassium compound used in the present invention. It is a complex salt consisting of silicic acid or/and phosphoric acid and potassium or/and calcium. The raw materials and properties used in the present invention are as follows. 1. Phosphate rock Not only the high-grade phosphate rock normally used in the production of phosphoric acid or phosphate fertilizers, but also low-grade ones can be used. 2 Silicic acid-containing substances 1 Industrial waste (a) Coal ash, etc.; Coal ash (fly ash) discarded from coal-fired power plants contains various types and appropriate amounts of trace elements necessary for plants in addition to silicic acid. Therefore, it is suitable as a raw material for the fertilizer of the present invention.
A similar cement dust can also be used. (b) Slag: Slag obtained as a by-product of metal smelting, and other phosphor slags such as blast furnace slag and electric steel slag can be used. (c) Silicon dust: Silicon dust generated during the production of metal silicon, ferrosilicon, etc. contains a large amount of silicic acid and is suitable as a raw material for the chemical fertilizer of the present invention. 2. Natural silicic acid-containing materials: Serpentine, potassium feldspar, silica, etc. can be crushed and used easily. 3 Phosphoric acid or a mixed acid containing phosphoric acid Phosphoric acid is a normal wet phosphoric acid solution, and when producing fertilizer for soil lacking in sulfur content, a mixture of phosphoric acid and sulfuric acid is suitable. 4 Basic potassium compound One or a mixture of two or more of potassium hydroxide, potassium hydrogen carbonate, etc. Basic salts such as sodium, magnesium, calcium, etc. may be added as accelerators for ripening and baking reactions as necessary. use. 5 Trace element content Manganese sulfate or FTE (fried trace element) is used as a trace element source for manganese, and borax is used as a trace element source for boron. 6. Exothermic reaction accelerator Fuels such as coal, petroleum, wood, etc., organic substances that are easily combusted by external heating, such as alcohol fermentation residues, lignin waste liquid residues, petroleum liquefied gas residues, etc. Mixing the promoter facilitates the calcination reaction and saves fuel for external heating. To explain the manufacturing method of the present invention in detail, phosphate rock is crushed in advance. Pulverize the silicic acid-containing material if necessary, mix phosphate rock powder and silicic acid-containing powder, or add phosphoric acid or a mixed acid of phosphoric acid and sulfuric acid to the silicic acid-containing material and knead. Let the ripening reaction occur. This reaction liberates the easily reactive phosphate from the phosphate rock and the silicic acid from the silicic acid-containing material. Next, a basic potassium compound is added to the aged reaction product in the form of a powder or an aqueous solution,
If necessary, a substance containing trace elements is added, and more preferably an exothermic reaction accelerator is added and kneaded. The kneaded material can also be granulated and molded if necessary. Next, the kneaded product or its granulated product is fired at 200 to 500°C, and then cooled. Easily reactive phosphates and free silicic acid react with basic potassium compounds at low temperatures, resulting in a new chemical compound that contains silicic acid, phosphoric acid, potassium, and lime, which are sparingly soluble in water but soluble in potassium. Fertilizer can be obtained. As a reaction condition, the mixing ratio of each raw material is 50 to 150 parts by weight of silicic acid-containing material to 100 parts of phosphate rock.
Suitably, 50 to 200 parts of phosphoric acid (as H ₃ PO ₄ ) and 50 to 200 parts of a basic potassium compound are added.
There is no need to apply temperature to the aging reaction, and the reaction time is 1 to 10 hours, the firing temperature is 200 to 500°C, and the firing time is 1 to 10 hours. The reaction method can be either a continuous method or a batch method. To summarize the characteristics of the new chemical fertilizer of the present invention, it does not contain chlorine roots or sulfate roots (which can be included if necessary) that acidify the soil, and it is poorly soluble in water as an effective fertilizer ingredient. Contains large amounts of slow-release phosphoric acid, potash, and silicic acid, as well as a wide variety of trace ingredients in appropriate amounts, so it is suitable for compounding raw materials and does not cause concentration problems in plants even if large amounts are applied at once. Since there is little amount of fertilizer, it is possible to apply only the base fertilizer so that plants can absorb the required amount of fertilizer components when they need it, which saves labor. In addition, it is poorly soluble in water, so there is little leaching or runoff from the soil, saving fertilizer and helping to prevent fertilizer pollution of rivers and seawater. In addition, the fertilizer of the present invention can have appropriate alkalinity and is useful for correcting soil acidity, and the silicic acid that remains after the fertilizer components are absorbed by plants aggregates the soil by gelation. is brought about goodwill. Since this silicic acid gel has the property of adsorbing fertilizer components, it prevents the leaching of fertilizer components from the soil and allows the plants to gradually absorb and utilize the fertilizer components, and therefore has the characteristic of being a slow-release fertilizer. The novel chemical fertilizer of the present invention and its manufacturing method will be shown below in Examples. Example 1 250 g of phosphate rock powder and 330 g of coal ash were mixed, and this mixture was poured into 310 g of phosphoric acid solution (P ₂ O ₅ = 40%), mixed, stirred, and aged to undergo a reaction to decompose the phosphate rock and from the coal ash. Measure the release of silicic acid. 360 g of a 50% potassium hydroxide aqueous solution was added to this mixture, mixed uniformly, baked at 300 to 600°C for 5 hours, and then cooled to obtain 1000 g of a new gray chemical fertilizer. The ingredients of the obtained fertilizer are soluble phosphoric acid content 25.6
(%), soluble potassium content 15.2 (%), soluble silicic acid content
16.2 (%), was poorly soluble in water, and had a pH of 5.0. This fertilizer was used to cultivate paddy rice and conduct a fertilizer efficacy test. The results are shown in the table. In the standard area and the heavily fertilized area, concentration problems were observed from the early stage of growth, with 2 out of 3 pots dying and 1 pot not recovering until harvest time. The example plots followed a normal growth process from the time of planting.

[Table] Example 2 250 g of coal ash powder, 100 g of serpentine powder, and 110 g of potassium feldspar powder were mixed, and 620 g of a mixed solution of phosphoric acid and sulfuric acid (P ₂ O ₅ 25%, SO ₄ 5%) was kneaded for 8 hours. After the ripening reaction, a solution of 40 g of magnesium hydroxide and 220 g of potassium carbonate dissolved in 200 g of water was added and further kneaded, then calcined at 300-500°C for 5 hours and cooled to obtain 1000 g of a new chemical fertilizer. . The resulting fertilizer has a soluble phosphoric acid content of 15.8
(%), soluble potassium content 16.1 (%), soluble silicic acid content
At 21.0 (%), the pH was 8.0, which was weakly alkaline and poorly soluble in water.

Claims (1)

[Claims] 1. A silicic acid-containing material made of industrial waste and/or a natural product, or the silicic acid-containing material and phosphate rock are mixed with phosphoric acid or phosphoric acid and sulfuric acid, and the necessary trace element content is added and the mixture is aged and reacted. A new chemical fertilizer whose main ingredient is potassium silicate lime, which is made by adding a basic potassium compound and calcining it.