JP3661748B2 - INORGANIC COMPOSITION AND METHOD FOR MANUFACTURING THE SAME - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a soil-making material useful for crops that require silicic acid from soil such as rice, an inorganic composition that can be used as a fertilizer, and a method for producing the same.
[0002]
[Prior art]
Conventionally, calcium and potassium silicate fertilizers are used as siliceous fertilizers useful for rice cultivation. Keikal is manufactured from slag as a raw material and is a soil modifier mainly composed of SiO ₂ , CaO, and Al ₂ O ₃ for supplementing mainly alkali components and silicic acid. However, although calcium is soluble in silicic acid in excess of 30% by weight, elution is extremely reduced in the region of 5-7, which is close to the actual pH of the soil, and is very efficient as a source of silicic acid. It is bad material.
[0003]
Therefore, even when actually used, it is necessary to fertilize a large amount of 200 kg per field 10a, and the labor required for this is a heavy burden on the farmers. Because calcium is a material that does not contain any of the three elements of fertilizer, it is common to use it mixed with other fertilizers. For example, 40 kg of Yorin is mixed with 200 kg of calcium and sprayed widely. It is a prescription. Yoryu is known to have high elution in the pH range close to neutrality of the silicic acid contained in it, and it is recognized that it is a phosphate fertilizer and at the same time a source of silicic acid. It has been.
[0004]
Moreover, although it is said that the silicic acid elution property of a potassium silicate fertilizer is high compared with a calcium, it is inferior in pH 5-7 compared with a yorin, and cannot be said to be enough. Potassium silicate fertilizers are often fertilized in a mixed manner with Yorin as in the case of Kyal, and Yorin also plays a role as a source of siliceous material here.
[0005]
Various attempts have been made to improve the low silicic acid dissolution property, which is a disadvantage of the calcium, and based on the method of adding potash components, focusing on the relatively high dissolution property of potassium silicate fertilizer, among others, for example A novel fertilizer composition (Japanese Patent Publication No. 1-24759) and a method for producing slow-release molten potassium silicate bitter fertilizer (Japanese Patent Publication No. 2-3523) are disclosed. .
[0006]
The potassium component generally facilitates vitrification of the composition and improves the elution of silicic acid, but on the other hand, the product obtained is expensive because the potash raw material is expensive. It is uneconomical to increase the potash content to ensure the quality of the material. Since potassium is a strong alkali, the furnace material of the production equipment is eroded. Adding potash increases the viscosity of the melt. It is difficult, and there is a drawback that when the temperature is raised to lower it, potash is volatilized.
[0007]
On the other hand, it is known that the silicic acid content contained in yolin has high elution and high plant absorbability. It is known that SiO ₂ contained in phosphorus is about 20 to 25% by weight as commercially available, but the elution rate decreases when the silicic acid content is increased. That is, a test example in which silicic acid was dissolved in a 2% citric acid aqueous solution by adding silica to a general raw material composition of dissolved phosphorus fertilizer and then heating, melting and quenching (Industrial Chemical Journal Vol. 60, 1109) (1957) describes that the amount of silicic acid eluted in a 2% aqueous citric acid solution (initial pH is about 2) reaches a peak at about 30% by weight.
[0008]
JP-B-2-23514 discloses that the method for evaluating soluble silicic acid using a sodium acetate buffer solution having a pH of 4 has a high correlation with plant absorbability. It is believed that the pH of the solution is more neutral and that the dissolution of the composition used in the test by chance was interpreted as consistent with plant absorption. There is still no official method for silicic acid dissolution test, and various methods have been proposed.
[0009]
[Problems to be solved by the invention]
An object of the present invention is to provide an inorganic composition containing 30% by weight or more of SiO ₂ which is effective with a small amount of fertilization, and particularly has a high dissolution property around pH = 5 to 7 in actual soil. Another object of the present invention is to provide a material mainly containing silicic acid and containing phosphorus and alkali, which does not need to be mixed with phosphorus fertilizer before application by containing phosphorus. Furthermore, the present invention can be easily produced using ordinary phosphorus production equipment, and can be produced at low cost because it does not contain potash. For crops that require silicic acid in soil such as rice. It aims at providing the siliceous fertilizer and soil improvement material which are used.
[0010]
[Means for Solving the Problems]
The present invention is an inorganic composition in which the total amount of MgO, SiO ₂ , CaO, and P ₂ O ₅ as a main component is 87% by weight or more and does not contain potassium, and MgO is contained in the total of the components. It is an amorphous inorganic composition containing 1 to 20% by weight, SiO ₂ to 30 to 50% by weight. _Further, in the inorganic composition characterized by preferably comprising P 2 _{O 5} 1 to 12 wt%, a molar ratio _{(CaO + MgO) / (SiO} 2 + P 2 O 5) is 1.2 to 2.5 is there. Further, an inorganic composition 4 wt% sodium citrate buffer (pH initial value 5.5) dissolution rate of silicic acid to is characterized in that at least ^50%, measured ^NMR-29 Si The inorganic composition is characterized in that the chemical shift value is −80 ppm or more and −72 ppm or less and the half width is 13 ppm or more and 23 ppm or less.
[0011]
The present invention is the above-mentioned method for producing an inorganic composition, wherein a melt obtained by blending raw materials into a desired composition and heating and melting is rapidly cooled.
[0012]
Moreover, this invention is the fertilizer characterized by containing the said inorganic composition, and a soil modifier.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, as a result of the inventors searching for a composition containing SiO ₂ having a high elution property in a high pH range of pH = 5 or higher, the elution property is greatly changed by the crystallinity even in the same composition. And an amorphous composition having a specific composition was found to exhibit silicic acid elution at the high pH range.
The present invention is characterized in that the main component is MgO, SiO ₂ , CaO, P ₂ O ₅ , contains 1 to 20 wt% MgO, 30 to 50 wt% SiO ₂ , and is amorphous. It is an inorganic composition. In the present invention, the main component of the inorganic composition is composed of MgO, SiO ₂ , CaO, P ₂ O ₅ , and the total amount may be 87% by weight or more, preferably 90% by weight or more. Many of the conventionally known silicic acid elution properties include potassium as a main component, such as potassium silicate fertilizer, while the inorganic composition of the present invention does not have this as a main component. There is. As a result, it is possible to eliminate defects such as high product prices, erosion of furnace materials in manufacturing facilities, and difficulty in operation.
[0015]
It is essential that the inorganic composition of the present invention is amorphous in order to enhance the elution of silicic acid. Regarding the degree of amorphousness, according to the results of experimental studies by the present inventors, the chemical shift value of NMR- ²⁹ Si (hereinafter simply referred to as NMR-Si) has a half-value width of 10 ppm or more. If it is enough.
[0016]
The inorganic composition of the present invention has a SiO ₂ content of 30% by weight or more. If it is less than this, a sufficient silicic acid elution amount cannot be secured, and the value as siliceous material or fertilizer decreases. If it exceeds 50% by weight, the elution of silicic acid is greatly lowered, and the elution in a region close to neutrality is deteriorated. 32-45% by weight is a preferred range.
[0017]
MgO has the effect of lowering the melting temperature of the inorganic composition and the effect of increasing the elution rate of silicic acid, and is also effective as a fertilizer component, so it needs to be contained in an appropriate amount. If the amount is less than 1% by weight, these effects are not sufficient, and if it exceeds 20% by weight, the absorbability of the fertilizer component of the applied plant is antagonized, which is inconvenient. From the above balance, 7 to 18% by weight is a preferable range.
[0018]
The inorganic composition of the present invention, it is preferred that P ₂ O ₅ content is 1-12 wt%. If P ₂ O ₅ is less than 1% by weight, the melting point of the melt will rise and the elution rate of silicic acid will tend to be low. May occur. On the other hand, if the amount exceeds 12% by weight, it may not be preferable because the required application amount of silicic acid may exceed the appropriate application amount of P ₂ O ₅ . The above range is selected because the elution rate of silicic acid is increased, the mixing and application of phosphorus fertilizer is not required, and an appropriate P ₂ O ₅ application rate can be maintained, and the range of 4 to 10% by weight is further increased. preferable.
[0019]
Further, the inorganic composition of the present invention, and molar basis (CaO + MgO) / (SiO 2 + P 2 O 5) ratio is preferably from 1.2 to 2.5. When the ratio is less than 1.2, the silicic acid elution amount decreases. On the other hand, when the ratio exceeds 2.5, the SiO ₂ content may decrease, the melting point may increase, and the silicic acid elution may decrease. 1.3 to 2.0 is a preferable range.
[0020]
In the inorganic composition of the present invention, boron or manganese that is effective as a trace component can be contained in addition to the above-mentioned components constituting the main component. The presence of boron and manganese has the effect of lowering the melting temperature and increasing the fluidity of the melt in the production method described later, promotes amorphousization of the resulting inorganic composition, and promotes the elution of silicic acid. There is also an effect. Also, iron oxides and aluminum oxides inevitably mixed may be included. However, for aluminum, there is no fertilizer effect, reducing the content of active ingredients, and increasing the amount adversely affects the elution of silicic acid, so the amount of Al ₃ O ₃ should be 2% by weight or less. It is preferable to suppress.
[0021]
The inorganic composition of the present invention has an elution rate of silicic acid content of 4% by weight citrate buffer (initial value of pH 5.5) of 50% or more, and an inorganic composition having a preferred composition range of 70% or more. In addition, according to the measurement result of the bonding state of ²⁹ Si by NMR, a chemical shift value is observed at −80 ppm or more and −72 ppm or less, and the half width is 13 ppm or more and 23 ppm or less. Here, the elution rate of the present invention represents the amount of silicic acid eluted in the citrate buffer as a percentage of the total amount of SiO ₂ in the inorganic composition.
[0022]
As described above, as a method for examining the elution property of silicic acid content of inorganic compositions, particularly fertilizers, soil modifiers, etc., a method using a 2% aqueous citric acid solution (pH is about 2), the initial value of pH is Although the method using 4 sodium acetate buffer is known, the pH at the time of elution is low, and it is inappropriate as a method for evaluating the elution of silicic acid near pH = 5-7 near the pH of soil. It is. As a result of various studies, the present inventors have found that a method using a 4% by weight citrate buffer (the initial value of pH is 5.5) is suitable. This method makes it possible to evaluate the elution properties of silicic acid to the soil of fertilizers and soil modifiers.
[0023]
The method for evaluating soluble silicic acid in the present invention is characterized by using a 4 wt% citrate buffer (initial value of pH is 5.5), and may be performed as exemplified below. That is, in the case of a large amount of fertilizer or soil modifier, a sample of about 100 g is collected from the fertilizer or soil modifier by a conventionally known method, the sample is pulverized by a vibration mill, and has an opening of 150 microns. Use a sieve and use it as an evaluation sample of soluble silicic acid. Weigh 1 g of the evaluation sample, add 150 ml of 4 wt% sodium citrate buffer adjusted to pH 5.5 by adding 2N sodium hydroxide aqueous solution to citric acid aqueous solution, and rock in a 30 ° C. water bath for 1 hour. . After the filtrate obtained by filtering the solution with a filter paper is diluted with pure water, the amount of SiO ₂ contained in the filtrate is measured by ICP (inductively coupled plasma emission spectroscopy).
[0024]
In addition, NMR- ²⁹ Si is measured by pulverizing the inorganic composition with a vibration mill to form a sieve having an opening of 150 microns. For example, using GX270 manufactured by JEOL, high power decoupling is performed under magic angle spinning. What is necessary is just to measure about 8000 times at intervals of 10 seconds in the combined mode, and to adjust the chemical shift to -33.8 ppm as polydimethylsilane. Incidentally, the half-value width of the single crystal silicon was adjusted to 0.17 to 0.072 ppm using adamantane so that the half-value width of the ¹³ C high magnetic field resonance peak was 0.147 to 0.072 ppm. It was 7 ppm. When the inorganic composition of the present invention is measured under the above-mentioned conditions, the obtained NMR- ²⁹ Si exhibits a chemical shift value in a range from −80 ppm to −72 ppm, and the half-value width varies between 13 and 23 ppm. Show.
[0025]
Regarding NMR-Si of the inorganic composition of the present invention, the peak shape on the chart is substantially determined by the composition, but is also affected by the production method. In particular, according to the production method of the present invention to be described later, even the same composition can be obtained with a larger peak half-value width.
[0026]
Furthermore, the present inventors have found that the silicic acid elution rate of the inorganic composition correlates with the NMR-Si chemical shift value. Specifically, the chemical shift is from −80 ppm to −72 ppm. The inorganic composition having a value and a half width of 13 ppm or more and 23 ppm or less has a citrate buffer elution rate of 70% or more at pH = 5.5 (initial value) of silicic acid.
[0027]
The elution rate can be easily estimated only by performing solid MNR measurement of a sample using the above correlation, and it is possible to omit the time-consuming evaluation of soluble silicic acid. In the measurement of silicic acid elution using a citric acid solution, there are various analytical problems such as the influence of coexisting ions in the solution, changes in the pH of the solution after elution, and repolymerization of the eluted silicic acid. In the measurement of NMR-Si, there is no such trouble.
[0028]
The method for evaluating soluble silicic acid based on NMR-Si has an effect that it is excellent in accuracy as compared with a conventionally known method. That is, it is considered that the chemical shift value of NMR-Si reflects the state of connection of the tetrahedral structure of SiO ₄ , and the half width represents the randomness of atomic arrangement. As a method of discriminating the randomness of atomic arrangement, that is, the amorphous state, there is generally a method of viewing a diffraction pattern using an X-ray diffractometer. However, even if the sample has the same composition and a broad pattern similar to that obtained by X-ray diffraction, the elution of silicic acid may be different. As another method for discriminating the vitrification state, a method is known in which bromoform is dropped using an optical microscope, the state of each sample particle is examined under transmitted light, and the vitrification state is quantitatively determined from the number. (Industrial Chemical Journal 63, 477, 1960), but this method is very time-consuming.
[0029]
Regarding the method for obtaining the inorganic composition of the present invention, as raw materials, P, such as phosphate rock, serpentine, quartzite, limestone, ferronickel ore, ferromanganese ore, various blast furnace irons, various steelmaking irons, phosphorus slag, fly ash, etc. Usual raw materials containing ₂ O ₅ , CaO, MgO, or SiO ₂ can be used. Some of the raw materials contain alumina (Al ₂ O ₃ ), but the presence of Al ₂ O ₃ deteriorates the elution rate of silicic acid, and when the content of Al ₂ O ₃ increases, Since the content is substantially reduced, an increase in the Al ₂ O ₃ content is not preferable. Al ₂ O ₃ or to use a material that does not contain, or Al ₂ materials O ₃ is included is used is limited to a small amount, the amount of Al ₂ O ₃ that in the inorganic composition obtained 2 It is preferable to set the weight% or less.
[0030]
The raw material, in consideration of such amount of volatiles, such product has a desired composition, i.e., the MgO 1 to 20% by weight, of SiO ₂ so as to contain 30 to 50 wt%, preferably P ₂ More preferably, the molar ratio (CaO + MgO) / (SiO ₂ + P ₂ O ₅ ) is 1.2 to 2.5 so that O ₅ is 1 to 12% by weight and melted at a high temperature. To do.
[0031]
As the furnace (melting furnace) used for melting, an electric furnace such as an external heating electric furnace, an arc furnace, a high-frequency heating furnace, or various combustion gas furnaces including a flat furnace can be used. Although it depends on the composition, the melting temperature is preferably 1350 ° C. or higher. When the raw material having the target composition is melted at a temperature higher by about 150 ° C. or more than the temperature at which it completely melts, a sufficient cooling rate can be obtained between the melting temperature and a temperature at which crystallization does not proceed. Among the melting furnaces, as will be described later, an electric furnace and a flat furnace are selected because the melt can be rapidly cooled and an amorphous inorganic composition can be easily obtained.
[0032]
The rapid cooling of the melt is essential for achieving an amorphous state of the resulting inorganic composition and enhancing the elution of silicic acid. The rapid cooling is generally performed by applying a method of spraying water having a weight 20 to 40 times that of the melt to the melt extracted from the furnace, a method of immersing in a large amount of water, or the like. As a cooling method for obtaining the inorganic composition of the present invention, the time required from the melting temperature to 100 ° C. is preferably 20 seconds or less, preferably 10 seconds or less. Since it is desirable that the time between 200 ° C. is within 5 seconds, a method of cooling by applying a jet water flow is preferable. Further, the cooling method using a jet water stream can also obtain an effect that a sand-like material can be obtained directly from the melt and pulverization as a post-process can be omitted.
[0033]
The obtained sandy substance can be used as it is as a fertilizer and soil modifier, but can also be supplied in a form that is easy to handle during fertilization by further grinding and granulating as necessary. . Further, if necessary, other fertilizers such as nitrogen and potash can be mixed to obtain a composite fertilizer having a desired composition.
[0034]
【Example】
Hereinafter, the present invention will be described in more detail based on examples and comparative examples.
[0035]
[Example 1]
1.57 g, 3.65 g, 0.34 g, 1.95 g, 5.17 g, respectively, mixed with ore (from China), serpentine, ferronickel ore, silica, and calcium carbonate (manufactured by Wako Pure Chemical Industries, Ltd.) It put in the platinum crucible, and it put in the electric furnace and heat-melted at 1500 degreeC. The melt taken out from the electric furnace was quickly poured into water to obtain a composition.
[0036]
The _{composition, P 2 O 5, SiO 2} , MgO, CaO , respectively 5.6 wt%, 36.5 wt%, 16.0 wt%, contained 37.4 wt%. Therefore, the molar ratio (CaO + MgO) / (SiO ₂ + P ₂ O ₅ ) is 1.64.
[0037]
The composition was pulverized and classified, and used as the powder below 150 microns for the following evaluation. The elution silicic acid amount (hereinafter referred to as C-SiO ₂ amount) in 4% sodium citrate buffer (initial value of pH is 5.5) is 30.9%, and the dissolution rate (hereinafter referred to as the dissolution rate). ) Was 85%. When NMR-Si was measured, the peak position was -73.3 ppm, and the half width was 16.0 ppm.
[0038]
[Example 2]
Phosphorous ore, serpentine, ferronickel ore, silica, and limestone were mixed at 25.0 kg, 31.9 kg, 3.4 kg, 21.5 kg, and 39.3 kg, respectively, and charged into a 100 kVA DC arc electric furnace. And heated and melted. Water flow was sprayed on the melt flowing out from the tap opening of the electric furnace, and it was rapidly cooled and granulated.
[0039]
This pulverized product contained 7.7% by weight, 38.7% by weight, 14.3% by weight and 34.9% by weight of P ₂ O ₅ , SiO ₂ , MgO and CaO, respectively. Therefore, the molar ratio (CaO + MgO) / (SiO ₂ + P ₂ O ₅ ) is 1.40.
[0040]
This composition was pulverized and classified, and powder under 150 microns was used for evaluation. The amount of C—SiO _{2 in} 4% sodium citrate buffer (the initial pH value was 5.5) was 35.9%, and the dissolution rate was 93%. When NMR-Si was measured, the peak position was -76.5 ppm and the half width was 18.6 ppm.
[0041]
Example 3
2.19 g, 3.28 g, 0.34 g, 1.70 g, and 5.34 g of phosphate rock, serpentine, ferronickel ore, silica, and calcium carbonate (manufactured by Wako Pure Chemical Industries, Ltd.) were mixed. The composition was obtained by the same operation.
[0042]
The _{composition, P 2 O 5, SiO 2} , MgO, CaO , respectively 7.7 wt%, 32.9 wt%, 14.3 wt%, contained 40.9 wt%. Therefore, the molar ratio (CaO + MgO) / (SiO ₂ + P ₂ O ₅ ) is 1.80.
[0043]
This composition was pulverized and classified, and powder under 150 microns was used for the following analysis. The amount of C—SiO _{2 in} 4% sodium citrate buffer (pH = 5.5) was 30.1%, and the dissolution rate was 91%. When NMR-Si was measured, the peak position was -73.1 ppm and the half width was 13.8 ppm.
[0044]
Example 4
1.10 g, 2.14 g, 0.34 g, 2.76 g, and 7.13 g of phosphate rock, serpentinite, ferronickel ore, silica, and calcium carbonate were mixed, respectively, and the composition was prepared in the same manner as in Example 1. Obtained.
[0045]
This composition contained 4.0% by weight, 37.5% by weight, 9.6% by weight and 45.3% by weight of P ₂ O ₅ , SiO ₂ , MgO and CaO, respectively. Therefore, the molar ratio (CaO + MgO) / (SiO ₂ + P ₂ O ₅ ) is 1.60.
[0046]
This composition was pulverized and classified, and powder under 150 microns was used for the following analysis. The amount of C—SiO _{2 in} 4% sodium citrate buffer (pH = 5.5) was 32.0%, and the dissolution rate was 85%. When NMR-Si was measured, the peak position was -74.6 ppm, and the half width was 14.0 ppm.
[0050]
【The invention's effect】
The inorganic composition of the present invention has an elution rate of 50% or more in 4 wt% citrate buffer (the initial value of pH is 5.5) in the total SiO ₂ , and a large amount of soluble silicic acid in the soil. In addition, the composition does not contain an alkali metal element such as potassium, so that it is easy to manufacture, so that the silicic acid content in the soil has a useful function, especially rice Useful as soil-making material or fertilizer.
[0051]
Both the fertilizer and soil modifier of the present invention have a feature that a lot of soluble silicic acid is contained in the soil and a feature that the composition contains a phosphoric acid component, so that the amount of fertilization can be reduced, and the phosphate quality Mixing of fertilizer and siliceous fertilizer is not necessary, enabling labor saving in the farmer, good silicic acid absorption, which can prevent crop pest damage, and better absorb various fertilizer components. It has many advantages such as increased yield, slow-acting, no fertilization, and poor solubility in water, so it has many advantages such as reducing the number of fertilizer application without running away in rainwater. .

Claims (4)

The total amount of MgO, SiO ₂ , CaO, and P ₂ O ₅ as main components is 87% by weight or more, and is an inorganic composition that does not contain potassium, and contains 1 to 20% by weight of MgO and 30% of SiO ₂ . 50 _wt%, the P 2 _{O 5} contained 12% by weight, the ratio of _{(CaO + MgO) / (SiO} 2 + P 2 O 5) when the molar basis is 1.2 to 2.5, NMR- The chemical shift value at the time of ²⁹ Si measurement is −80 ppm or more and −72 ppm or less, the half width is 13 ppm or more and 23 ppm or less, and 4 wt% citrate buffer in the total SiO ₂ (the initial value of pH is 5. An inorganic composition characterized in that the elution rate to 5) is 50% or more . Raw materials were blended to a desired composition, a manufacturing method of claim 1, wherein the inorganic composition characterized by rapidly cooling the melt obtained by heating and melting. Fertilizer, characterized in that it contains claim 1, wherein the inorganic composition. Soil amendment, characterized in that it contains claim 1, wherein the inorganic composition.