JPS6246518B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention is characterized in that the phosphoric acid concentration is 50 to 80% by weight as H ₃ PO ₄ (36 to 58% by weight as P ₂ O ₅ ) in a mixture of powder of an alkaline earth metal compound and powder of a substance containing soluble silicic acid. When reacting _a concentrated phosphoric acid solution or a mixed acid solution of phosphoric acid solution and sulfuric acid with the above _{concentration} ,
Hydrochloric acid of 0.05 to 0.6 mol of HCl is added and reacted, and the treated product after the reaction contains a soluble phosphoric acid component or a combination of a soluble phosphorus component and a water-soluble phosphoric acid component, and the treated product after the reaction is particularly This is a method for producing phosphoric acid fertilizer that can be made into granules suitable for fertilization without going through a drying process. The concentrated phosphoric acid solution used in the present invention is a concentrate of the so-called wet method phosphoric acid solution produced by decomposing phosphate ore with mineral acid, and contains sulfuric acid, water, and a small amount of impurities associated with the manufacturing process and raw material ore. a liquid containing
Alternatively, dry process phosphoric acid dissolved in water may be used. In addition, soluble silicic acid, soluble lime, and soluble magnesia indicated in the present invention are defined by the fertilizer analysis method.
Refers to the silicic acid content, lime content, and magnesium content obtained by dissolving a predetermined amount of 0.5M HCl using a predetermined method. Phosphate fertilizers include fast-acting phosphate fertilizers whose main ingredient is mostly water-soluble phosphoric acid, such as superphosphate lime and heavy superphosphate lime, and water-soluble phosphate fertilizers, such as dissolved phosphorus fertilizers. Some crops do not contain phosphoric acid, but contain soluble phosphoric acid, which dissolves in the acid released from the roots during the growth process of crops. Water-soluble phosphoric acid plays a necessary role in the early stages of crop growth, but over time it becomes less soluble and becomes fixed due to the iron and aluminum content in the soil, causing it to lose its fast-acting properties. On the other hand, soluble phosphoric acid is slow-release, so it has the advantage of being effective in soils where phosphoric acid is easily fixed.
It is especially effective in soils with a high phosphate absorption coefficient, such as volcanic ash soil. For this reason, phosphoric acid fertilizers containing highly soluble phosphoric acid are used as fertilizers for soil improvement, and are used in conjunction with water-soluble phosphoric acid fertilizers that are expected to have quick-acting effects. In addition, in recent years, phosphoric acid fertilizers that retain both water-soluble phosphoric acid content and water-soluble phosphoric acid content have appeared, and for example, the following are known. (1) Manufactured from dissolved phosphorus fertilizer, superphosphate lime (or heavy superphosphate lime), and phosphoric acid solution. (2) Manufactured from dissolved phosphorus fertilizer and heavy superphosphate lime or phosphoric acid solution. (3) Manufactured by heating and decomposing magnesium in ferronic acid slag with a mixed solution of phosphoric acid and sulfuric acid, converting the magnesium into magnesium phosphate. As mentioned above, the present invention allows the ratio of the water-soluble phosphoric acid content to the water-soluble phosphoric acid content to be adjusted arbitrarily in the treated product after the reaction, resulting in good granulation properties and the ability to form products without going through a special drying process. This is a method for producing a phosphoric acid fertilizer. The reaction of a powder of an alkaline earth metal compound such as calcium or magnesium with a phosphoric acid solution can produce an alkaline earth metal compound as an oxide, such as MeO.
It is expressed by the following formula. MeO＋ _2H3PO4 →Me（H2PO4） ₂・_nH2O …… _{( 1} ) MeO＋ _H3PO4 → _{MeHPO4 ・ nH2O} ……(2) (In the above formula, Me is an alkali such _as Ca or Mg. In other words, in the reaction of equation (1), phosphoric acid-lime and phosphoric acid-magnetic earth are produced, which are water-soluble phosphates, and in the reaction of equation (2), dicalcium phosphate is produced. , dimagnesium phosphate is produced, and these are soluble phosphates. In the reactions of equations (1) and (2) above, when a large amount of water exists in the reaction system, the reaction rate becomes faster, and the reaction of equation (2) takes priority regardless of the amount of phosphoric acid added. However, if an excess of phosphoric acid remains, the soluble MeHPO ₄ · nH ₂ O to be produced further reacts with the phosphoric acid, resulting in MeHPO ₄ · nH ₂ O + H ₃ PO ₄
The reaction mechanism is →Me(H ₂ PO ₄ ) ₂・nH ₂ O. On the other hand, when the amount of water in the reaction system is small, the reaction of equation (1) takes priority regardless of the amount of phosphoric acid added, and if unreacted MeO remains, a reaction occurs with this remaining MeO. Me(H ₂ PO ₄ ) ₂ ·nH ₂ O gradually reacts to produce MeHPO ₄ ·nH ₂ O. This second
The reaction of the steps varies significantly depending on the type of alkaline earth metal compound used. For example, when carbonate powder such as limestone or dolomite is used, the reaction is weak, and even if the treated product is brought into contact with a large amount of water after the reaction, the reaction rate only increases slightly. When a strongly alkaline compound such as , magnesia or magnesium hydroxide is used, the reaction rate becomes faster. Therefore, even if dolomite powder remains unreacted, it may remain as a small amount of water-soluble phosphoric acid. In general, alkaline earth metal compounds and _{H3PO4 concentrations} are
A water-soluble phosphate compound, Me( _{H2PO4 ) 2.nH2O} , is produced by reacting with a 50-80% by weight concentrated phosphoric acid solution _.
If , the treated product is highly viscous immediately after the reaction, and then tends to solidify with the passage of time, and the viscosity further increases. The present invention makes use of such properties to make the processed product after the reaction into a form suitable for fertilization as it is, and moreover, it is possible to make it into a product without going through a drying process. . Further, among alkaline earth metal compounds, carbonate has a low raw material price, and moreover, it releases carbon dioxide gas during the reaction, so the reactant foams and becomes bulky, making it easier for excess water to evaporate. However, simply reacting alkaline earth metal carbonate with a highly concentrated phosphoric acid solution results in a highly viscous treated product after the reaction, and it will not solidify unless it is aged for a considerable period of time and may be crushed or crushed. Not only is the operation for granulation difficult, but the water-soluble phosphoric acid content (W-
P ₂ O ₅ ) gradually reacts with unreacted alkali and turns into a soluble component, resulting in poor component stability and impractical. On the other hand, as in the method of the present invention, the H ₃ PO ₄ concentration is 50
By adding a small amount of hydrochloric acid to a ~80% by weight concentrated phosphoric acid solution and reacting it, it is possible to significantly reduce the viscosity of the treated product after the reaction. This has been confirmed through experiments, and in this case, by appropriately adjusting the amount of hydrochloric acid added, the crushing and granulating properties of the treated product after the reaction are significantly improved. The stability of the components is also improved. Furthermore, when powder of a substance containing soluble silicic acid is added to powder of an alkaline earth metal compound, a silicic acid gel is formed by the reaction between the silicic acid contained therein and the phosphoric acid solution, resulting in a treatment product after the reaction. It was recognized that the physical properties of the product were further improved, and that the product could be obtained by a nearly continuous process of reaction → crushing → granulation, while shortening the aging period. Moreover, during the continuous process, a part of the water content evaporates due to the heat of reaction or is consumed as water of crystallization of the reaction product, so that the product can be made into a product as it is without any additional drying process. Can be done. In the phosphoric acid fertilizer obtained by the method of the present invention, it is possible to change the guaranteed phosphoric acid content while leaving a certain proportion of water-soluble phosphoric acid in the water-soluble phosphoric acid content, or to add excess water to H ₃ PO ₄ . If a certain amount of MeO is present, further addition of sulfuric acid to remove MeO as sulfate can be carried out in a conventional manner. However, when sulfuric acid is added at this time, the viscosity of the reaction product becomes even higher, which has a negative effect on the subsequent steps of crushing and granulation. It was confirmed that the adjustment was effective. The reaction conditions in the present invention are as follows (1), (2), (3),
As shown in (4). (H ₃ PO ₄ )/[(MeO) − {1/2 (HCl) + (H ₂ SO ₄ )}] Molar ratio = 1.0 to 2.0 ………(1) where MeO: soluble alkaline earth metal compound ( MeO is the number of moles of CaO, MgO) Molar ratio of acids used in the reaction (H ₃ PO ₄ ) > (H ₂ SO ₄ ) + (HCl) ...... (2) Amount of hydrochloric acid added (when adding sulfuric acid) (HCl)/(H ₃ PO ₄ ) molar ratio = 0.05 to 0.6
...(3) Amount of hydrochloric acid added when sulfuric acid is not added (HCl)/(H ₃ PO ₄ ) Molar ratio = 0.05 to 0.3
...(4) Theoretically (H ₃ PO ₄ )/[(MeO)-{1/2(HCl)
+ (H ₂ SO ₄ )}] When reacted at a molar ratio of 1.0, all compounds of phosphoric acid and MeO are MeHPO ₄・nH ₂ O
All compounds of phosphoric acid and MeO in the same formula when the molar ratio = 2.0 become Me(H ₂ PO ₄ ) ₂ ·nH ₂ O, and are water-soluble (C-P ₂ O ₅ ). W-
P ₂ O ₅ ). Therefore, the ratio of W-P ₂ O ₅ /C-P ₂ O ₅ can be arbitrarily adjusted within the range of molar ratio = 1.0 to 2.0. On the other hand, if the molar ratio is less than 1.0, MeO remains unreacted, but if carbonate is used as a raw material, some water-soluble phosphoric acid may also remain. The effect of hydrochloric acid added in the method of the present invention is extremely remarkable, and as a result of examining its effect on reducing the viscosity of the treated product after the reaction, the following was confirmed. That is, first, the phosphoric acid concentration is 50 to 80 as H ₃ PO ₄ .
When a high concentration phosphoric acid solution (wt%) reacts with an alkaline earth metal compound, Me
(H ₂ PO ₄ ) ₂ ·nH ₂ O is produced, but the crystals of this produced compound are extremely fine, and although it is water-soluble, it is extremely viscous. On the other hand, MeHPO ₄ .nH ₂ O, which is produced with a time delay, has good crystallinity and a large crystal size, and therefore has poor agglomeration among crystal particles. Furthermore, when the amount of added hydrochloric acid was changed and the product identification was examined using powder X-ray diffraction, it was found that as the amount of added hydrochloric acid increased, the amount of MeHPO ₄ · nH ₂ O produced tended to increase. Admitted. This tendency for the production amount of MeHPO ₄ .nH ₂ O to increase also showed a tendency to increase as the amount of hydrochloric acid added increased when sulfuric acid was used, and no particular change was observed. A process diagram of the method for producing phosphoric acid fertilizer of the present invention is shown in FIG. In the process diagram in Figure 1, A is the raw material alkaline earth metal compound powder, B is the powder of the substance also containing soluble silicic acid, and C is the concentration of 50 to 80% by weight.
Concentrated phosphoric acid solution, D indicates hydrochloric acid, and E indicates sulfuric acid. In Fig. 1, M is a mixture of raw materials A and B, N is the addition of a concentrated phosphoric acid solution C and hydrochloric acid E, or the addition of a mixed acid solution of concentrated phosphoric acid solution C and sulfuric acid E and hydrochloric acid E; 2 is reaction, 2 is aging, 3 is granulation by crushing and rotation, 4 is sieving steps, 5
indicates the product. In the method of the present invention, the mixing ratio of the alkaline earth metal compound powder and the powder of the substance containing soluble silicic acid, which are the raw materials, is 20 to 20% of the former.
A range of 60% by weight is desirable. By the method of the present invention, a concentrated phosphoric acid solution alone or a concentrated phosphoric acid solution and sulfuric acid is added to a mixture of a powder of an alkaline earth metal compound and a powder of a substance containing soluble silicic acid in a predetermined quantitative ratio. Hydrochloric acid is added to the mixed acid solution to cause the reaction, and after the reaction is completed, the reaction product is lightly crushed after ripening, and then granulated by simply applying rotational motion, and can be fertilized simply by sieving without drying. A product consisting of granules of suitable particle size can be obtained. The phosphoric acid fertilizer thus obtained contains both a water-soluble phosphoric acid component and a water-soluble phosphoric acid component. The finer the particle size of the raw material powder used in the present invention, the better the reactivity, but a particle size of about 50 to 100 mesh is usually economical, and the concentration of the concentrated phosphoric acid solution used is H ₃ PO ₄ It was recognized that 50-80% by weight as _P2O5 and 36-58% by weight as _P2O5 is most desirable. In addition, it is desirable that the hydrochloric acid used be of high concentration.
It was found that hydrochloric acid with a concentration of 35% was most suitable. As a guaranteed value of the ingredients that should be contained in the official standards based on Article 3 of the Fertilizer Control Law, soluble phosphoric acid content is
Approximately 35%, of which approximately 10 to 20% is water-soluble phosphoric acid (water-soluble phosphoric acid is the number of soluble phosphoric acid components, and over time it reacts with unreacted alkali components and turns into soluble components) In order to obtain a product containing both phosphoric acid and phosphoric acid, it is necessary to allow a considerable amount of margin as a guaranteed component in the actual manufacturing design. (H ₃ PO ₄ )/[(MeO)-{(H ₂ SO ₄ )+1/2 (HCl)}] molar ratio = 1.0 to 2.0 (however, MeO is soluble in the raw powder mixture) without adding sulfuric acid. (indicates the number of moles of alkaline earth metal oxide), and the molar ratio of concentrated phosphoric acid solution (H ₃ PO ₄ ) to hydrochloric acid (HCl) is 1 of H ₃ PO ₄
Experiments have shown that the addition effect is best when the amount of HCl is 0.05 to 0.30 mol.
When the amount exceeds 0.30 mol, the reaction product loses its caking properties, and a binder (granulating agent) is particularly required for granulation, and when the amount is less than 0.05 mol, the effect of adding hydrochloric acid cannot be obtained. In addition, the guaranteed values for the ingredients that should be contained in the official standards based on Article 3 of the Fertilizer Control Law are approximately 10-25% for soluble phosphoric acid and 5-10% for water-soluble phosphoric acid.
% (in consideration of the change in water-soluble phosphoric acid to water-soluble phosphoric acid, in actual manufacturing design, a considerable amount of component margin is expected). The powder of the substance containing soluble silicic acid in the powder mixture is preferably about 10 to 30% by weight, and (H ₃ PO ₄ )/[(MeO)−{(H ₂ SO ₄ )+1
/2 (HCl)} molar ratio = 1.0 to 2.0, and (H ₃ PO ₄ mol) > (H ₂ SO ₄ mol) + (HCl mol), HCl/
It was found that the granulation properties of the resulting product were better when the molar ratio of H ₃ PO ₄ was 0.5 to 0.6 and the amount of sulfuric acid used was smaller than the amount of hydrochloric acid used. The powder of the alkaline earth metal compound used as a raw material in the present invention includes crushed powder of limestone, dolomite, magnesite, etc., crushed powder of chemically synthesized calcium carbonate, magnesium carbonate, serpentine, peridotite, etc. Quicklime, magnesia, light calcined dolomite powder obtained by calcining
It includes hydrates of slaked lime, magnesium hydroxide, dolomite plaster, etc., dry powders of magnesium-containing substances obtained by treating pulp waste liquid, and sintered products, either singly or in mixtures of two or more. In addition, powders of substances containing soluble silicic acid include
Mineral slag, cement dust, fly ash, pulverized coal combustion ash, pulverized powder of tuff-based natural zeolite rocks, ALC, produced during the production of iron, steel, ferroalloy, nickel, stainless steel, phosphoric acid, etc.
(Lightweight plate-shaped molded article for construction) Contains substances whose main component is calcium silicate, which is produced as a by-product during production, either singly or in a mixture of two or more. Examples of the invention are described below. Example 1 (H ₃ PO ₄ )/[MeO) − {1/2 (HCl) + (H ₂ SO ₄ )}] Molar ratio = 1.16 (HCl)/(H ₃ PO ₄ ) Molar ratio = 0.52 So, magnesia calcium carbonate powder (0.149
mm standard sieve), CaO34.1%, MgO17.5%,
Alkaline content 58.4%, including soluble lime (S-CaO)
34.1%, soluble magnesium (S-MgO) 17.5%) 358Kg
and granulated blast furnace slag powder (98% passing through 0.08mm standard sieve, SiO ₂ 32.9%, Al ₂ O ₃ 18.2%, CaO 39.4%,
MgO5.7%, Fe ₂ O ₃ 0.8%, including soluble silicic acid (S
-SiO ₂ ) 28.9%, soluble lime (S-CaO) 39.3
%, soluble magnesium (S-MgO) 4.5%) was mixed with 120 kg to obtain 478 kg of a raw material powder mixture. Next, 396 kg of phosphoric acid solution with H ₃ PO ₄ concentration of 75% (P ₂ O ₅ concentration of 55%), 180 kg of hydrochloric acid with HCl concentration of 35% and
711 Kg of a mixed acid solution consisting of 135 Kg of sulfuric acid with a H ₂ SO ₄ concentration of 98% was prepared. 711 kg of the above mixed acid solution for 478 kg of raw powder mixture
Kg was adjusted using a powder metering mixer and a metering pump, respectively, and the mixture was continuously charged into a dispersion mixer (trade name: Flowjet Mixer) for reaction. The reaction was violent and rapid. The reaction product was discharged onto a belt conveyor and immediately continuously crushed and granulated to obtain 1000 kg of granular phosphate fertilizer having a particle size of about 1 to 4 mm. One day after the production of this phosphoric acid fertilizer, and at a temperature of 36
After being left in a constant temperature and humidity room at 90% relative humidity for one week, the component analysis values were as follows.

[Table] Example 2 (H ₃ PO ₄ )/{(MeO)-1/2(HCl)} Molar ratio = 1.33 (HCl)/(H ₃ PO ₄ ) Example 1 so that the molar ratio = 0.30 5.434 kg of the same magnesian calcium carbonate powder used in , and 6.91 kg of dry pulverized powder that can pass through a 100-mesh sieve, commonly known as Oya stone, which is a type of tuff-based natural zeolite whose main component is clinoptilolite. were mixed in advance to obtain 12.344 kg of powder mixture. The chemical analysis values of the Oya stone used are as follows. CaO 2.29% MgO 0.30% SiO ₂ 66.42% Al ₂ O ₃ 13.12% Fe ₂ O ₂ 1.90% S-SiO ₂ (soluble silicic acid) 1.70% Also, what are the soluble lime content and soluble magnesium content specified in the fertilizer analysis method? It was also 0%. Next, 2.02 kg of hydrochloric acid with an HCl concentration of 35% was mixed with 8.08 kg of a phosphoric acid solution with a H ₃ PO ₄ concentration of 75% (P ₂ O ₅ concentration of 55%) to prepare a 10.10% Kg mixed acid solution. The powder mixture was put into a mixing and dispersing machine with an internal volume of 100, and then a mixed acid solution of phosphoric acid and hydrochloric acid was added thereto, and the stirring blade of the mixing and dispersing machine was slowly rotated to cause a reaction. The contents undergo a vigorous decarboxylation reaction and foam. The bubbling phenomenon subsides after a while. At this stage, the reaction is continued while the stirring blade of the mixing/dispersing machine is continuously rotated for several minutes. The contents gradually become viscous and the load on the mixing/dispersing machine increases. At this point, once the rotation of the stirring blade is stopped and the stirring blade is allowed to stand still for several minutes, the stirring blade of the mixing and dispersing machine is rotated again to crush and granulate at the same time. When the temperature reached the temperature, the stirring blade was stopped and the contents were taken out from the mixer and disperser, and after taking out, 20 kg of product was obtained by simply sieving without further drying. The analytical values of the phosphoric acid fertilizer obtained as described above were as follows, one day after production and one week after being left in a constant temperature and constant humidity room at a temperature of 35° C. and a relative humidity of 90%.

_[ Table] Example _{3 Dolomite} plaster ₍ 90% passing through 0.088mm standard sieve, CaO50.00%, MgO26.00%,
Of these, 3.986 kg of soluble lime (S-CaO 50.00%, soluble magnesium (S-MgO) 26.00%) and 2.112 kg of the same blast furnace water slag powder used in Example 1 were mixed in advance to produce 6.098 kg. A powder mixture was obtained. Next, 12.888 kg of a phosphoric acid solution with a 75% H ₃ PO ₄ concentration (55% P ₂ O ₅ concentration) was mixed with 1.014 kg of hydrochloric acid with a 35% HCl concentration to prepare 13.902 kg of a mixed acid solution. Thereafter, it was treated in the same manner as in Example 2 to obtain 20 kg of product. The analytical values of the phosphoric acid fertilizer obtained as described above were as follows, one day after production and one week after being left in a constant temperature and constant humidity room at a temperature of 35° C. and a relative humidity of 90%.

[Table] Example 4 (H ₃ PO ₄ )/{(MeO)-1/2(HCl)} Molar ratio = 1.33 (HCl)/(H ₃ PO ₄ ) Example 1 so that the molar ratio = 0.10 3.134Kg of the same magnesian calcium carbonate powder used in the above and 9.822Kg of pulverized coal combustion ash (fly ash) were mixed in advance to produce 12.956Kg.
A powder mixture was obtained. The chemical analysis values of the fly ash are as follows. CaO 7.83% MgO 2.10% SiO ₂ 48.10% Al ₂ O ₃ 28.63% Fe ₂ O ₃ 6.72% Soluble lime (S-CaO) specified by fertilizer analysis method
5.57%, soluble magnesium (S--MgO) 0.97%, and soluble silicic acid (S--SiO ₂ ) 2.70%. Next, 0.640 kg of hydrochloric acid with a HCl concentration of 35% was mixed with 7.814 kg of a phosphoric acid solution with a H ₃ PO ₄ concentration of 75% (P ₂ O ₅ concentration of 55%) to prepare 8.454 kg of a mixed acid solution. Thereafter, it was treated in the same manner as in Example 2 to obtain 20 kg of product. The analytical values of the phosphoric acid fertilizer obtained as described above after one day of production and after being left in a constant temperature and humidity chamber at 35° C. and 90% relative humidity for one week were as follows.

[Table] Example 5 (H ₃ PO ₄ )/{MeO-1/2(HCl) + (H ₂ SO ₄ )} Molar ratio = 1.54 (HCl)/(H ₃ PO ₄ ) Molar ratio = 0.05 As shown, 5 kg of the same magnesian calcium carbonate powder used in Example 1 was mixed with 5 kg of powder obtained by crushing phosphorus-containing steelmaking slag produced in the dephosphorization process of hot metal and passing it through a standard sieve of 0.149 mm. , total 10Kg
I got it. The chemical analysis values of this phosphorus-containing slag are as follows. T-P ₂ O ₅ 7.74% SiO ₂ 17.1% CaO 52.5% MgO 0.83% T-Fe 6.23% C-P ₂ O ₅ 5.15% Soluble silicic acid (S-SiO ₂ ) 15.4% Soluble lime (S-CaO) 51.1 % Soluble magnesium (S-MgO) 0.69% Next, phosphate rock containing 60% H ₃ PO ₄ concentration (44.7% P ₂ O ₅ equivalent) and 5.70% sulfuric acid with H ₂ SO ₄ was decomposed with sulfuric acid and concentrated. HCl concentration 35 in crude phosphoric acid solution 21.8Kg
% hydrochloric acid was mixed to prepare 22.5 kg of mixed acid. The following process was carried out in the same manner as in Example 2, and a product with a size of 1 to 4 mm was obtained.
Obtained 27.6Kg. One day after manufacturing this product and at 35℃ and 90% relative humidity.
The analytical values when the sample was left in a constant humidity room for 7 days were as follows.

[Table] Example 6 (H ₃ PO ₄ )/{(MeO)-1/2(HCl) + (H ₂ SO ₄ )} Molar ratio = 1.60 (HCl)/(H ₃ PO ₄ ) Molar ratio = 0.20 10 kg of a mixture of equal amounts of the magnesium calcium carbonate powder used in Example 1 and the same phosphorus-containing steel slag powder as used in Example 5 was prepared. Next, phosphate rock containing 60% H ₃ PO ₄ concentration (44.7% P ₂ O ₅ equivalent) and 5.70% sulfuric acid with H ₂ SO ₄ was decomposed with sulfuric acid, and the HCl concentration was added to 21.8 kg of concentrated crude phosphoric acid solution.
2.70 kg of 35% hydrochloric acid was mixed to prepare 24.5 kg of mixed acid. Thereafter, the same process as in Example 2 was carried out to obtain 29.5 kg of a product with a diameter of 1 to 4 mm. 1 day and 35 days after the manufacture of this product
When the sample was left in a constant humidity room at 90% relative humidity for 7 days, the analytical values were as follows.

【table】 [Brief explanation of the drawing]

FIG. 1 is a process flow diagram of the method for producing phosphoric acid fertilizer of the present invention.

Claims (1)

[Scope of Claims] 1. A mixture of a powder of an alkaline earth metal compound and a powder of a substance containing soluble silicic acid has a phosphoric acid concentration of 50 to 80% by weight as H ₃ PO ₄ (36 to 80% by weight as P ₂ O ₅₎ .
When reacting a phosphoric acid solution (58% by weight) or a mixed acid solution of a phosphoric acid solution and sulfuric acid with the above concentration,
A method for producing a phosphoric acid fertilizer, which comprises adding 0.05 to 0.6 mol of hydrochloric acid to 1 mol of H ₃ PO ₄ for reaction. 2. Alkaline earth metal compounds include crushed limestone, dolomite, and magnesite, chemically synthesized calcium carbonate, magnesium carbonate, serpentine, and peridotite, quicklime obtained by firing, magnesia, and light calcined Dolomite powder, slaked lime, magnesium hydroxide, hydrate powder such as dolomite plaster, dried magnesium-containing substance obtained by treating pulp waste liquid, or alkaline earth metal compound powder such as calcined product alone or in combination 2. The method for producing a phosphoric acid fertilizer according to claim 1, which comprises a mixture of more than one species. 3 Substances containing soluble silicic acid include iron, steel, ferroalloy, nickel, stainless steel, manganese,
Mineral slag during the production of magnesium, phosphoric acid, etc.
Cement dust, fly ash (pulverized coal combustion ash), natural zeolite-containing substances such as Oya stone, ALC
(Lightweight plate-shaped molded product for construction) It is characterized by being made of a powder of a substance containing soluble silicic acid, such as a substance mainly composed of calcium silicate, which is a by-product during manufacturing, or a mixture of two or more of them. A method for producing a phosphoric acid fertilizer according to claim 1. 4 A mixture of a powder of an alkaline earth metal compound and a powder of a substance containing soluble silicic acid has a phosphoric acid concentration of 50 to 80% by weight as H ₃ PO ₄ (36 to 80% as P ₂ O ₅₎ .
When reacting a phosphoric acid solution (58% by weight) or a mixed acid solution of a phosphoric acid solution and sulfuric acid with the above concentration,
In the method of reacting by adding 0.05 to 0.6 mol of hydrochloric acid to 1 mol of H ₃ PO ₄ , a soluble alkaline earth metal oxide (MeO) (Me is Ca or Mg) in the raw material and a mixed acid solution (phosphoric acid , a mixed acid of sulfuric acid and hydrochloric acid), the molar ratio of (H ₃ PO ₄ )/[(MeO− {1/2(HCl)×(H ₂ SO ₄ )}] is 1.0 to 2.0. 1) Number of moles of (H ₃ PO ₄ ) > Number of moles of H ₂ SO ₄ + Number of moles of (HCl) ……(2) Molar ratio of (HCl)/(H ₃ PO ₄ ) = 0.05 to 0.6 …… (3) When reacting a phosphoric acid solution with hydrochloric acid without adding sulfuric acid, the molar ratio of (H ₃ PO ₄ )/[(MeO− {1/2(HCl) + (H ₂ SO ₄ )}] = 1.0 ~ 2.0 ... (4) Molar ratio of (HCl) / (H ₃ PO ₄ ) = 0.05 ~ 0.3 ... (5) Above (1), (2), (3), (4), (5) ) A method for producing a phosphoric acid fertilizer, characterized in that the reaction is carried out at a molar ratio that satisfies the conditions of 5. The alkaline earth metal compound is a crushed product of limestone, dolomite, magnesite, chemically synthesized calcium carbonate, Magnesium, serpentine, peridotite crushed products, quicklime obtained by firing, magnesia, lightly calcined dolomite powder, hydrated powder such as slaked lime, magnesium hydroxide, dolomite plaster, etc., obtained by processing pulp waste liquid. The method for producing a phosphoric acid fertilizer according to claim 4, characterized in that it consists of a powder of an alkaline earth metal compound such as a dried magnesium-containing substance or a calcined substance alone or in a mixture of two or more. 6. If the substance containing soluble silicic acid is iron, steel, ferroalloy, nickel, stainless steel, manganese,
Mineral slag during the production of magnesium, phosphoric acid, etc.
Cement dust, fly ash (pulverized coal combustion ash), natural zeolite-containing substances such as Oya stone, ALC
(Lightweight plate-shaped molded product for construction) It is characterized by being made of a powder of a substance containing soluble silicic acid, such as a substance mainly composed of calcium silicate, which is a by-product during manufacturing, or a mixture of two or more of them. A method for producing a phosphoric acid fertilizer according to claim 4.