JP4246782B2 - Manufacturing method of siliceous fertilizer - Google Patents

Description

  The present invention relates to a method for producing siliceous fertilizer using mainly converter slag produced by hot metal pretreatment.

Conventionally, granulated slag discharged from the blast furnace in the steel manufacturing process, separated and manufactured by water cooling, and converter slag produced by hot metal pretreatment in the converter, such as rice aggregate in addition to raw materials such as aggregate for concrete, etc. It has also been used effectively as a fertilizer for scallops (for example, Non-Patent Documents 1 and 2 and Patent Document 1).
However, in the fertilizer using blast furnace slag, the slag is simply crushed to 3 mm or less, or the insufficiently soluble (citric acid soluble) phosphoric acid (P ₂ O ₅ ) is added. In addition, the ratio of soluble silicic acid in silicic acid (SiO ₂ ), which is a constituent material of slag, is small, and therefore silicic acid is difficult to elute into the soil. The soluble silicic acid here refers to silicic acid that is leached when a substance containing silicic acid is shaken in a 0.5N hydrochloric acid solution at 30 ° C. for 1 hour, and lime (CaO) that is leached in the same test is It is called soluble lime.

On the other hand, conventional converter slag is not only supplied with oxygen but also lime, iron ore and Mn ore as auxiliary raw materials and is processed at a high temperature of around 1600 ° C., because it adds a lot of lime. It was not a low basicity slag having a basicity of 3 or less, had a low silicic acid content, and had a low content of soluble silicic acid in silicic acid as in the blast furnace slag. In addition, since desulfurization is performed using soda ash, the soda content and sulfur content in the slag are large, making it unsuitable as a fertilizer for plants.
Soluble silicic acid is an important component for growing rice, and if this component is small, it will be prone to lodging by strong winds, and it will be vulnerable to pest and cold damage, and if soluble silicic acid is insufficient, growth and maturity will be poor. End up.
Moreover, it is needless to say that fertilizers are not limited to those with a large amount of active ingredients, but are more preferable than fertilizers, but even if the amount of application is reduced with the recent aging of farmers, There is an urgent need for the development of fertilizers that have the same or better effects, improve work efficiency, and reduce labor load.
Japanese Journal of Soil Fertilizer Vol. 58, No. 2 (1987), pp. 166-171 Japanese Journal of Soil Fertilizer Vol.61 No.4 (1990) 386-389 Japanese Patent Laid-Open No. 11-61118

  The present invention provides a method for producing a siliceous fertilizer having a high content of soluble silicic acid, which effectively utilizes slag produced in hot metal pretreatment in view of the above situation.

The present invention was made to solve the above problems by adding CaO powder to hot metal having a sulfur content of 0.03% or less and a silicon content of 0.8% or less in the hot metal preliminary treatment step. In addition, by blowing oxygen and desiliconizing and dephosphorizing the hot metal, the basicity (CaO / SiO ₂ ) is 3 or less, soluble silicic acid is 15 to 35%, soluble lime is 30 to 45%, soluble bitterness. A slag containing 8% or less of soil and 1-8% of soluble manganese is collected, and soluble phosphoric acid is added to the slag to make soluble phosphoric acid 5% or more.

  INDUSTRIAL APPLICABILITY The present invention can provide a fertilizer having a high content of soluble silicic acid, which is effective for the growth of sericultural plants, mainly utilizing converter slag produced by hot metal pretreatment, and has added soluble phosphoric acid to the fertilizer. By using it as a siliceous fertilizer, it is possible to obtain a yield that is significantly better than before. Moreover, it is possible to achieve an excellent effect even with a small amount of application, and there is a great advantage in improving the farm work efficiency and reducing the labor load, which greatly contributes to the development of industry.

The siliceous fertilizer of the present invention utilizes slag having a high content of soluble silicic acid of 15 to 35%, and the slag having such a high content of soluble silicic acid has a low content of sulfur and silicon. Or, lime enters between the networks of silicic acid constituting the slag by adding lime and oxygen to the hot metal whose sulfur and silicon content has been reduced by pretreatment of desulfurization and desiliconization beforehand, and desiliconizing and dephosphorizing. This is presumably because the structure has weakened the bonds between silicic acids. The main treatment of the siliceous fertilizer of the present invention is to remove the basicity of the slag to 3 or less, preferably 1.5 to 2.5 by blowing CaO powder into the hot metal together with oxygen through a lance. Silica and dephosphorization are performed. By doing so, a siliceous fertilizer having a high content of soluble silicic acid can be obtained. Incidentally, the hot metal pretreatment temperature in a normal converter requires a treatment at a high temperature of around 1600 ° C. because there are a large amount of auxiliary materials to be added as described above, but in the present invention, the amount of additive is Therefore, it is possible to process between 1250 and 1400 ° C., and preferably between 1300 and 1350 ° C. to produce a siliceous fertilizer containing desired basicity and soluble silicic acid. it can. Also, slag basicity (CaO / SiO ₂₎ is the not more than 3, it is impossible to increasingly lime in the slag and a soluble silica content to 15% or more. Moreover, it can be set as 20% or more soluble silicic acid content by setting it as 2.5 or less basicity. In acidic aqueous solution or neutral aqueous solution, Ca ²⁺ and OH ⁻ increase with the increase in slag basicity, as shown in Equation 1, so that silicate ions (SiO ₄ ⁴⁻ ) hardly exist. On the other hand, when the basicity of slag is less than 1.5, it is estimated that the network of silicic acid becomes strong, and the content of soluble silicic acid in the slag decreases. From the above, the basicity of slag is desirably between 1.5 and 2.5.

The siliceous fertilizer is required to have a stable quality, and before performing the main treatment in the production method of the present invention, a sample is taken in front of the converter to analyze the chemical composition of the hot metal, The main treatment is performed when the sulfur content (0.03%) and the silicon content (0.8%) are below the predetermined values.
However, when the content of sulfur and silicon in the hot metal is high, it is necessary to perform the above-described preliminary treatment. That is, when the sulfur content in the hot metal is higher than 0.03%, it becomes slag with a high sulfur content and becomes unsuitable as a fertilizer, and desulfurization must be performed in order to prevent deterioration of fertilizer quality. Normally, desulfurization is performed by blowing CaO or carbide through a lance when hot metal is in a kneading vehicle. At this time, for example, iron oxide or aluminum ash may be used as the oxidizing agent. The produced slag is separated and removed from the hot metal. Moreover, when the silicon content rate in hot metal is higher than 0.8%, it is necessary to perform preliminary desiliconization treatment in order to adjust the basicity of the slag. This preliminary desiliconization treatment is usually performed by transferring the desulfurized hot metal to a converter and blowing oxygen through a lance. Then, the hot metal has a sulfur content of 0.03% or less and a silicon content of 0.8% or less, and the produced slag is removed so as not to deteriorate the quality as a fertilizer raw material. The hot metal subjected to the above treatment can then be desiliconized and dephosphorized to obtain the desired siliceous fertilizer.

  In the present invention, the reason for limiting the content of soluble silicic acid in the siliceous fertilizer to 15 to 35% is that if it is less than 15%, the soluble silicic acid is insufficient as a fertilizer for scallops. Desirably, it is 20% or more. On the other hand, even if it exceeds 35%, the effect is not only saturated, but also the amount of added CaO for dephosphorization decreases and dephosphorization becomes insufficient. The reason why the content of soluble lime is limited to 30 to 45% is that soluble lime is an effective component for neutralizing soil and promoting the growth of scallops, and therefore requires 30% or more. However, if it exceeds 45%, the content of soluble silicic acid is low. Further, the content of highly soluble mould (MgO) is limited to 8% or less. Although bitter earth is used for correction of soil acidity together with lime, it is an important component as a phytonutrient and contained in chlorophyll in the plant body. In particular, this plant is effective in improving the taste of rice in the genus Molyceae, but the effect is saturated even when the content of the bitter soil exceeds 8%. The content of soluble manganese is limited to 1 to 8%. MnO is also an effective component for plant growth, and if it is less than 1%, it is not suitable as a fertilizer. However, the effect is saturated even if the content exceeds 8%.

The content of soluble phosphoric acid in the fertilizer varies depending on the purpose of use. The hot metal contains 0.1-0.2% phosphorus, but since the amount of slag produced by desiliconization and dephosphorization is large, the phosphoric acid contained in the siliceous fertilizer raw material is 5 %, Usually about 1 to 4%. Therefore, the content of soluble phosphoric acid in siliceous fertilizers for applications that do not particularly require phosphoric acid may be less than 5%. However, the content of soluble phosphoric acid in siliceous fertilizers for applications requiring a phosphoric acid content needs to be 5% or more. This is because if it is less than 5%, the effect of phosphoric acid cannot be exhibited sufficiently. Therefore, in the present invention, soluble phosphoric acid is added to the above slag to make the soluble phosphoric acid 5% or more. In addition, even if it contains exceeding 25%, since an effect is saturated, it is desirable to make an upper limit into 25%.
It goes without saying that the siliceous fertilizer according to the present invention is used for granulating a powder obtained by pulverizing the form of slag from the use of the fertilizer.

Hereinafter, specific examples will be described.
Desulfurization and dephosphorization of hot metal by directly blowing CaO powder with oxygen through a lance without desulfurization and desiliconization pretreatment to the hot metal in the converter with 0.024% S and 0.65% Si Then, slag having a basicity of 2.1 was collected, and this was pulverized and granulated to obtain siliceous fertilizer A shown in Table 1. Further, the amount of CaO powder added was changed in the same manner to fractionate slags having basicity of 2.6 and 1.6 to obtain siliceous fertilizers B and C shown in Table 1.
These siliceous fertilizers A, B, and C are reference examples in which the content of the soluble phosphoric acid is less than 5%.

In addition, CaO and aluminum ash were added to hot metal containing 0.036% S and 0.88% Si contained in a kneading vehicle to desulfurize, and the generated slag was removed. Next, oxygen was blown into the molten iron that had been desulfurized and injected into the converter to remove slag produced by preliminary desiliconization. The hot metal containing 0.007% S and 0.15% Si thus obtained was blown together with oxygen through CaO powder to desiliconize and dephosphorize the hot metal to separate slag with a basicity of 2.0. This was pulverized, granulated after adding soluble phosphoric acid, and made into siliceous fertilizer D shown in Table 1.
And the amount of CaO added in the same process was changed, and the slag which made basicity 1.6 and 2.7 was fractionated, and it was set as siliceous manure E and F shown in Table 1.
These siliceous fertilizers D, E, and F are examples of the present invention.
The fertilizer G in Table 1 is a fertilizer having conventional blast furnace granulated slag, and the fertilizer H is a fertilizer having conventional converter slag.
These fertilizers G and H are conventional examples.

Table 2 shows the results obtained by sprinkling various fertilizers shown in Table 1 on adjacent 10-R paddy fields having similar weather conditions and soil conditions to grow rice.
In the conventional fertilizer G, 200 kg per 10 ares was sprayed, and the result was a refined brown rice weight of 597 kg, a waste rice weight of 7.9 kg, and a ripening rate of 88.0%.
In addition, in the conventional fertilizer H, fertilizer was sprayed as 120 kg per 10 ares, but the yield was as low as the brown rice weight 552 kg, the waste rice weight was as large as 19.3 kg, and the ripening rate was as low as 83.7% Only the result was obtained.
On the other hand, in fertilizers D to F, which are the examples of the present invention, by spraying 60% of the conventional fertilizer G of 120 kg per 10 ares, the polished rice weight is 592-602 kg, and the waste rice weight is 6.8- 7.5 kg, the ripening ratio can all achieve excellent results of 90% or more, and this result can be confirmed to be much better than the result of the conventional fertilizer H sprayed with the same amount. . These excellent results are mainly due to the high content of soluble silicic acid.

Claims (1)

In the hot metal pretreatment process, CaO powder is added to hot metal with a sulfur content of 0.03% or less and a silicon content of 0.8% or less, and oxygen is blown into the hot metal to desiliconize and dephosphorize the hot metal. By doing so, the basicity (CaO / SiO ₂ ) is 3 or less, soluble silicic acid is 15 to 35%, soluble lime is 30 to 45%, soluble soluble clay is 8% or less, and soluble manganese is 1 to 8%. A method for producing a siliceous fertilizer, comprising separating slag contained therein and adding soluble phosphoric acid to the slag so that the soluble phosphoric acid is 5% or more.