WO2019004339A1 - Steelmaking slag for use as fertilizer starting material, method for producing steelmaking slag for use as fertilizer starting material, method for producing fertilizer, and fertilization method - Google Patents

Abstract

[Problem] To easily and inexpensively supply multiple types of elements as plant fertilizer while avoiding runoff caused by flowing water, even in acidic soils in regions which receive a lot of rainfall and regions where rivers often flood. [Solution] This steelmaking slag for use as a fertilizer starting material contains, in mass%, P2O5 in the amount or 2-8%, inclusive, MnO in the amount of 3-10%, inclusive, boron in the amount of at least 0.005% and less than 0.05%, total iron in the amount of at least 7% and less than 15%, CaO in the amount of 38-48%, inclusive, SiO2 in the amount of 22-30%, inclusive, sulfur in the amount of 0.1-0.6%, inclusive, MgO in the amount of 1-8%, inclusive, and Al2O3 in the amount of 0.5-3%, inclusive. The proportion of soluble P2O5 in the P2O5 is at least 50%, the proportion of soluble MnO in the MnO is at least 80%, the slag basicity is greater than 1.5 and no greater than 2.2, and the bulk specific gravity is 1.9-2.8, inclusive.

Description

Steelmaking slag for fertilizer raw material, manufacturing method of steelmaking slag for fertilizer raw material, manufacturing method of fertilizer and fertilization method

The present invention relates to a steelmaking slag for fertilizer raw material, a method for producing steelmaking slag for fertilizer raw material, a method for producing fertilizer, and a fertilizing method.

Elements essential for plant growth, nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), oxygen (O), hydrogen (H), carbon (C), magnesium (Mg), sulfur (S), iron (Fe), manganese (Mn), boron (B), zinc (Zn), nickel (Ni), molybdenum (Mo), copper (Cu) and chlorine (Cl) are known.

Among the above elements, nitrogen (N), phosphorus (P) and potassium (K) are called three elements of fertilizer, and are known to be elements required by a large amount of plants. Moreover, calcium (Ca), magnesium (Mg), and sulfur (S) are called secondary elements, and are said to be elements required by plants next to the above three elements. In addition, iron (Fe), manganese (Mn), boron (B), zinc (Zn), molybdenum (Mo), copper (Cu), and chlorine (Cl) are required to be contained in trace amounts by plants. being called.

Furthermore, among the above elements, boron (B) has recently been found to be an element necessary for the formation of cell walls of plant root cells. In addition, the major food crops of the world's population, such as rice, wheat and corn, are silicate crops that require large amounts of silicon (Si) in addition to the above elements.

One of the methods for supplying each element of Ca, P, Si, Mg, Fe, Mn, B and S to plants is foliar application. In foliar application, for example, the following substances are used for each element.
Ca: calcium chloride P: potassium monophosphate Mg: magnesium sulfate Fe: ferrous sulfate Mn: manganese sulfate B: boric acid,
Si: potassium silicate,
S: Calcium sulfate (gypsum), magnesium sulfate, ferrous sulfate, manganese sulfate

However, since foliar application is a labor-intensive method, there is a need for a method capable of absorbing each element as described above from the roots without relying on foliar application.

On the other hand, since steelmaking slag obtained by hot metal pretreatment and decarburization treatment of steelmaking industry contains various minerals as its component, as disclosed in Patent Documents 1 to 9 below, fertilizer and soil improvement are carried out. It is used as a material.

For example, in Patent Document 1 below, a raw material for silicic acid phosphate fertilizer recovered by dephosphorizing treatment during hot metal pretreatment of blast furnace hot metal in a steel making process, and a method for producing such raw material for silicic acid phosphate fertilizer, It has been reported.

Patent Document 2 below reports a method for producing a phosphate phosphate fertilizer using as a raw material steelmaking slag obtained from a hot metal pretreatment process of a steelmaking process.

In Patent Document 3 below, it is reported that the slag grains made of steelmaking slag of the iron making process have a sales increase effect of paddy rice and also have a control effect of greenhouse gas.

Patent Document 4 and Patent Document 5 below report a hot metal pretreatment method in which a silicon removal treatment and a dephosphorization treatment are sequentially performed using one converter-type refining furnace, and in Patent Document 6 below, A method has been reported for producing siliceous fertilizer in the hot metal pretreatment step of the iron making process.

Patent Document 7 below reports a siliceous fertilizer in which the elution of silicic acid is enabled by mixing coal ash containing only unleasable silicic acid with molten stainless steel slag. There is.

Patent Document 8 below reports a method for producing a phosphoric acid-containing slag for fertilizer, and Patent Document 9 below reports a method for producing a phosphate fertilizer raw material obtained from an iron making process.

Patent No. 5105322 Patent No. 6040064 Patent No. 5881286 Patent No. 5983900 JP, 2016-29206, A Patent No. 4246782 Patent No. 4040542 Patent No. 6119361 Patent No. 6011556

Applying various types of substances including elements such as P, Fe, Mn, Zn, Si, Ca, Mg, B, and S at a ratio at which the fertilizer effect of each element can be expected is costly and time-consuming. In addition, when applying a substance containing each element to the soil, the specific gravity is different for each substance, so a substance with a small specific gravity may run away in soil in areas with high rainfall or in areas with high river flooding. is there. As a result, it is feared that the plant will not have to be grown under conditions lacking balance among the elements during the period of planting where the plant is grown.

In acidic soils in particular, elements such as Fe, Mn, and B may run out and run short. In addition, in an acidic soil having a high aluminum content, aluminum is ionized to bind to phosphoric acid, resulting in aluminum phosphate, which may inhibit phosphate absorption by plant roots.

The ability to stably grow silicic plants such as rice, wheat, corn, etc. in acidic soils with high rainfall or in areas with high rainfall in rivers, especially acidic soils with high aluminum content, means stable food It is also very important from the viewpoint of supply.

Therefore, in acidic soils with high rainfall or high river basins, especially in acidic soils with high aluminum content, P is considered to be insufficient among the three elements of fertilizer, and trace elements And Fe, Mn, B, etc. are considered to be insufficient.

Further, among secondary elements, Ca and Mg are elements necessary for root growth and photosynthesis of plants. In addition, such Ca and Mg show alkalinity as lime and magnesia, and are the main constituent elements of the alkali component measured by the fertilizer analysis method etc., and increase the pH of the acidic soil to a pH suitable for plant cultivation. It is also an element that has the effect of improving.

Further, among secondary elements, S is an element essential for biosynthesis of sulfur-containing amino acids, and is an element particularly necessary for cultivating plants of the family Liminaceae or liliaceae such as garlic, onion and green onion. However, S is an element that can be oxidized to sulfuric acid after being added to the soil to acidify the soil, or can be reduced to hydrogen sulfide to be a cause of root rot by the action of sulfate reducing bacteria. It is.

In addition, Si is an element necessary for stably cultivating silicic acid plants such as rice, wheat and corn, and is extremely important also from the viewpoint of stable supply of food.

Thus, even with acidic soils in areas with high rainfall or areas with high river weirs, many types of elements such as P, Fe, Mn, Si, Ca, Mg, S, and B are washed away by water flow. There is a need to develop fertilizers and fertilization methods that can be supplied as plant fertilizers easily and at low cost.

Therefore, the present invention has been made in view of the above problems, and the object of the present invention is to prevent runoff by water flow even in acidic soils in areas with high rainfall or areas with many river ridges. It is an object of the present invention to provide a steelmaking slag for fertilizer material, a method for producing steelmaking slag for fertilizer material, a method for manufacturing fertilizer, and a fertilizing method, which can supply various elements as plant fertilizers easily and at low cost.

As a result of intensive investigations made by the present inventors in view of the above problems, steelmaking specialized for fertilizer raw materials in order to supply many kinds of elements such as P, Fe, Mn, Si, Ca, Mg, B and S The present inventors have completed the present invention by developing a method for producing slag and a method for producing the same, and a method for producing a fertilizer and a method for applying fertilizer capable of supplying each of these elements.
The gist of the present invention is as follows.

[1] by mass%, P ₂ O ₅ : 2% to 8%, MnO: 3% to 10%, boron: 0.005% to 0.05%, total iron: 7% to 15% , CaO: 38% or more and 48% or less, SiO ₂ : 22% or more and 30% or less, sulfur: 0.1% or more and 0.6% or less, MgO: 1% or more and 8% or less, Al ₂ O ₃ : 0.5 % to 3% or less, containing the proportion of soluble _P 2 _{O 5} in the _P 2 _{O 5} is, is 50% or more, the proportion of Ku-soluble MnO in the MnO is at least 80%, ( Steelmaking slag for fertilizer materials whose slag basic degree represented by CaO content / SiO ₂ content is more than 1.5 and 2.2 or less, and bulk specific gravity is 1.9 or more and 2.8 or less.
[2] The steelmaking slag for a fertilizer raw material according to [1], which contains 2CaO · SiO ₂ -3CaO · P ₂ O ₅ solid solution and FeO-MnO-CaO-SiO ₂ solid solution respectively.
[3] The steelmaking slag for a fertilizer material as set forth in [1] or [2], wherein the proportion of hexasoluble boron in the boron is 95% or more.
[4] Any one of [1] to [3], wherein the mass ratio of particles having a particle diameter of less than 5 mm as a whole and having a particle diameter of less than 600 μm is 60% or more with respect to the total mass. Steelmaking slag for fertilizer raw materials described in 1).
It is a manufacturing method of steelmaking slag for fertilizer materials as described in any one of [5] [1]-[4],
For the converter-type pan, the void ratio represented by (the freeboard corresponding to the length from the furnace opening to the melt surface / the height in the furnace corresponding to the length from the furnace opening to the bottom of the furnace) is 0. Blast furnace hot metal is injected so as to be 5 or more and 0.9 or less, and at least one of manganese ore, manganese-containing decarburized slag, and ferromanganese is added to the blast furnace hot metal in the converter-type pan Quicklime and / or calcium carbonate and oxygen having an average particle size of 1 mm or less from the lance inserted into the blast furnace hot metal, and slag at 1300 ° C. or more and 1400 ° C. or less Is subjected to dephosphorization treatment, and the slag basicity represented by (CaO content / SiO ₂ content) is more than 1.5 and 2.2 or less, and the MnO content in the slag is 3 mass % To 10% by mass Manufacturing method for producing steelmaking slag for fertilizer raw materials.
[6] The method for producing steelmaking slag for fertilizer material according to [5], wherein the molten slag after the dephosphorization treatment is poured into a dish-shaped heat-resistant container and solidified by rapid cooling.
[7] The method for producing steelmaking slag for fertilizer material according to [6], wherein the molten slag after the dephosphorization treatment is rapidly cooled by watering.
[8] The molten slag after the dephosphorization treatment is inclined to the slag pot by tilting the converter-type pan, and then the molten slag in the slag pot can be tilted to the first heat-resistant container capable of tilting. The molten slag is rapidly cooled and solidified by sprinkling water in the first heat resistant container, and then the solidified slag is crushed and the first heat resistant container is tilted. The method of producing steelmaking slag for fertilizer material according to any one of [5] to [7], wherein the solidified slag is broken down by sliding it into a second heat resistant container.
[9] According to any one of [5] to [8], the 2CaO · SiO ₂ -3CaO · P ₂ O ₅ solid solution and the FeO-MnO-CaO-SiO ₂ system solid solution are respectively formed by rapid cooling. The manufacturing method of steelmaking slag for fertilizer raw materials as described.
[10] Pulverize the slag so that the mass ratio of particles having a particle diameter of less than 5 mm as a whole and having a particle diameter of less than 600 μm is 60% or more of the total mass, [5] to [5] The manufacturing method of steelmaking slag for fertilizer raw materials as described in any one of 9).
[11] The method for producing steelmaking slag for fertilizer raw material according to any one of [1] to [4] or the production method for steelmaking slag for fertilizer raw material according to any one of [5] to [10] The manufacturing method of a fertilizer which powderizes the manufactured steelmaking slag for fertilizer raw materials.
[12] The method for producing fertilizer according to [11], wherein a predetermined binder is added to the pulverized steelmaking slag for a fertilizer material, and then granulated.
[13] The method for producing fertilizer according to [11] or [12], wherein an organic substance is further mixed with the obtained fertilizer.
[14] The method for producing fertilizer according to [13], wherein the organic matter is at least one of livestock manure, plant residue, and compost obtained from fish and shellfish.
[15] The steelmaking slag for a fertilizer material according to any one of [1] to [4], and the manufacturing method for a steelmaking slag for a fertilizer material according to any one of [5] to [10]. fertilizer feedstock steel slag, or [11] to a fertilizer with fertilizer which is manufactured by the manufacturing method of fertilizer according to any one of [14], pH (H 2 O) is 4 or more and 6 or less Yes, the method of fertilization is applied to soil with a value of (pH (H ₂ O)-pH (KCl)) of 1 or more and effective phosphoric acid of 5 mg / 100 g or less dry soil .
[16] The fertilization method according to [15], wherein the applied amount of the fertilizer is 0.05 t / ha or more and 2 t / ha or less as the steelmaking slag for fertilizer material.
[17] The fertilization method according to [15] or [16], wherein the fertilizer is sown on the surface of the soil layer or mixed with the soil layer before sowing or planting seedlings.
[18] The fertilization method according to [15] or [16], wherein the fertilizer is spread on the surface of the soil layer in the vicinity of the plant to be grown, or mixed into the soil layer.

As described above, according to the present invention, even in the case of acid soil in a high rainfall area or an area with a high flow of rivers, various types of elements can be easily and cost-effectively without runoff by water flow. It becomes possible to supply as a fertilizer.

Hereinafter, preferred embodiments of the present invention will be described in detail.

(About the examination contents which the present inventors did)
Prior to describing the embodiments of the present invention, the results of the study conducted by the inventors regarding the request for the fertilizer and the fertilizing method as described above will be described in detail.

<Study on technology disclosed in Patent Document 1>
With regard to the requirements as described above, the raw material for silicic acid phosphate fertilizer disclosed in the above-mentioned Patent Document 1 has a basicity of 1.0 or more and 1.4 or more as represented by (CaO content / SiO ₂ content). Because of the lower basicity of the following, it is difficult to produce an effect on acidic soils. Moreover, since the content of soluble CaO is as low as 30 mass% or less and the basicity is weak, the raw material for silicic-acid phosphate fertilizer currently disclosed by the said patent document 1 also has a weak basicity, It is hard to be effective also in acidic soil.

Furthermore, in Patent Document 1, although _Al 2 _{O 3} content is described that 10 mass% or less, referring to Examples, _Al 2 _{O 3} content is 4.84 mass% or more 6 .33 mass% or less, which is a high value exceeding 4 mass%. A lower Al ₂ O ₃ content is desired because Al is a substance that easily binds to phosphate ions and is a cause of interfering with phosphorus absorption in plants.

Moreover, in the said patent document 1, the description regarding content of boron, and the description regarding the fertilizer effect of boron do not exist.

<Study on technology disclosed in Patent Document 2>
Although Patent Document 2 discloses a method of producing mineral phosphate phosphate fertilizer using as a raw material steelmaking slag obtained from the hot metal pretreatment process of iron making process, the method of producing steelmaking slag as a raw material of mineral phosphate phosphate fertilizer is disclosed There is no description about In addition, according to the example of Patent Document 2 above, the content of ultrasoluble phosphoric acid of steelmaking slag as a raw material is 2.56% by mass or more and 2.62% by mass or less, which is a standard of mineral phosphate phosphate fertilizer It can be seen that the condition of “soluble phosphoric acid content of 3% by mass or more” can not be satisfied. Moreover, in the said patent document 2, the description regarding content of boron and manganese, and the description regarding the fertilizer effect of boron and manganese do not exist.

<Study on technology disclosed in Patent Document 3>
Although the patent document 3 describes that the content of phosphoric acid is 1.5% by mass or more and 5% by mass or less, a soluble phosphoric acid (of which any proportion can effectively act on plants) There is no description as to whether it is phosphoric acid (eluting with Petermann ammonium citrate solution).

Patent Document 3 describes that the content of CaO is 20% by mass or more and 50% by mass or less. As the reason for this content, it is shown that, in the iron making process, steelmaking slag having a CaO content of less than 20% by mass or more than 50% by mass is hardly generated.

In Patent Document 3, the slag grains consisting of steelmaking slag, that contains a SiO ₂ 30% by weight or less than 10 wt% are described. In Patent Document 3, as the reason, when the amount of SiO ₂ is less than 10% by mass, the amount of the released silicic acid to be eluted decreases, so that the function of generating oxygen by photosynthesis on the soil surface of the paddy field covered with water It has been shown that the effect of promoting the growth of diatoms having the above can not be expected. Further, Patent Document 3 shows that it is difficult to obtain steelmaking slag which contains more than 30% by mass of SiO ₂ in the iron making process, and therefore hardly obtained.

Since there is no description about the basicity (= CaO / SiO ₂ ) of slag in the Patent Document 3, as described above, the content of CaO is 20% by mass to 50% by mass, and SiO ₂ Content of 10% by mass to 30% by mass or less, and the basicity of the slag is 0.67 (CaO: 20% by mass, SiO ₂ : 30% by mass) to 5 (CaO: 50% by mass) , SiO ₂ : 10% by mass)). Since the basicity of slag is strongly related to the elution of fertilizer active ingredients such as phosphorus, iron and manganese, it is considered necessary to set the basicity suitable for the elution of these fertilizer effective elements.

Furthermore, in patent document 3, it is described that the slag grain which consists of steelmaking slag contains 3.5 mass% or more and 10 mass% or less of MnO. In Patent Document 3, as the reason, when the content of MnO is less than 3.5% by mass, there is a possibility that the elution of polyvalent manganese may not occur sufficiently to raise the redox potential of the paddy soil. It is shown that there is. Here, the application rate described in Patent Document 3 is 0.5 t / ha or more and 5 t / ha, and a polyvalent manganese sufficient to raise the redox potential of the paddy soil at the application rate within this range. It is assumed that the elution of If the application rate is less than the above range, it may be necessary to examine the conditions under which manganese is eluted more efficiently.

As described above, in Patent Document 3, since there is no description regarding the basicity of slag, in the range of the basicity of 0.67 to 5 assumed from the CaO content and the SiO ₂ content of Patent Document 3, phosphorus and No study has been conducted on the basicity suitable for efficient elution of manganese.

Moreover, in patent document 3, there is no description regarding boron, and there is also no description regarding what kind of structure of slag dissolves phosphorus, calcium, silicon, manganese and the like. In addition, the application rate is 0.5 t / ha or more and 5 t / ha, which requires a large amount of application, which is disadvantageous because the cost for fertilizer and the cost for labor to apply it are disadvantageous.

<Study on technologies disclosed in Patent Document 4 and Patent Document 5>
In the hot metal pretreatment method disclosed in Patent Document 4 and Patent Document 5, silicic acid effective for fertilizer is contained by sequentially performing desiliconization treatment and dephosphorization treatment using one converter type refining furnace. And slag containing phosphoric acid are separately collected. However, it is preferable that silicic acid and phosphoric acid be contained together as the fertilizer. Further, separately performing the desiliconization treatment and the dephosphorization treatment requires time and cost from the viewpoint of obtaining a slag which is a raw material of the fertilizer. Moreover, in patent document 4 and patent document 5, it does not disclose at all about the composition of the dephosphorization slag manufactured, and the description regarding a fertilizer does not exist, either. Therefore, it can not be judged whether the slag currently indicated by these patent documents 4 and patent documents 5 is a thing suitable for a fertilizer.

Also, in order to properly control the composition of the slag to be produced, the inventors of the present invention, as described in detail below, the freeboard in the converter-type pan (ie, the length from the furnace opening to the hot metal surface) ) Is considered an important condition. However, Patent Document 4 does not disclose at all a freeboard when performing desiliconization treatment and dephosphorization treatment in order using one converter-type smelting furnace. Moreover, although the ratio of a free board is described only in the desiliconization process in patent document 5, there is no description about a free board about a dephosphorization process.

<Study on technology disclosed in Patent Document 6>
Patent Document 6 discloses a method of producing a siliceous fertilizer in a hot metal pretreatment step of an iron making process, and adding a soluble phosphoric acid to a converter slag produced by the hot metal pretreatment, the phosphoric acid is added in 5 mass It is stated that it makes it more than%. Moreover, in patent document 6, it is described that it is 1 mass% or more and 4 mass% or less about phosphoric acid content of original slag. In addition, Patent Document 6 does not describe at all the content of boron and the fertilizer effect of boron. Moreover, in patent document 6, there is no description regarding the freeboard in the case of slag manufacture, and there is also no description regarding the collection | recovery method and the cooling method by discharge of slag.

<Study on technology disclosed in Patent Document 7>
Patent Document 7 discloses a siliceous fertilizer in which the elution of silicic acid is enabled by mixing coal ash containing only unleasable silicic acid with a molten stainless steel slag. However, such siliceous fertilizer contains a large amount of chromium because it is a stainless steel slag. Therefore, there is a concern that the chromium content of the soil may increase if a large amount of fertilizer based on such slag is applied or applied for a long period of time. In addition, it is necessary to mix coal ash, which causes cost increase due to the increase of operation.

<Study on technology disclosed in Patent Document 8>
Patent Document 8 discloses a method for producing a phosphoric acid-containing slag for fertilizer, and the phosphoric acid content of the phosphoric acid-containing slag for fertilizer is set to 18.32% by mass or more. However, such phosphoric acid content largely deviates from the phosphoric acid content of steelmaking slag which can be produced by hot metal pretreatment and decarburizing treatment of a normal iron making process, and hot metal pretreatment and decarburizing treatment of a normal iron making process In processing, manufacture is impossible. Therefore, a special process is required to produce such slag, which causes cost increase.

<Study on technology disclosed in Patent Document 9>
Patent Document 9 also discloses a method for producing a phosphoric acid fertilizer raw material obtained from the iron making process, and the phosphoric acid content of the slag as the phosphoric acid fertilizer raw material is 15% by mass or more. However, such phosphoric acid content largely deviates from the phosphoric acid content of steelmaking slag which can be produced by hot metal pretreatment and decarburizing treatment of a normal iron making process, and hot metal pretreatment and decarburizing treatment of a normal iron making process In processing, manufacture is impossible. Therefore, a special process is required to produce such slag, which causes cost increase.

As described above in detail, there are various problems to be solved when manufacturing steelmaking slag of iron making process as fertilizer raw material or using steelmaking slag of iron making process as fertilizer raw material capable of supplying various minerals. Exists.

As a result of intensive studies on the above problems, the present inventors have made steelmaking slag specialized for fertilizer raw materials in order to supply various elements such as P, Fe, Mn, Si, Ca, Mg, B and S. And its production method, fertilizer production method and fertilizer application method capable of supplying each of these elements, fertilizer raw materials capable of supplying various elements as plant fertilizers more easily and at low cost It was possible to obtain steelmaking slag for use. Hereinafter, embodiments of the present invention will be described in detail.

(Embodiment)
<About general steelmaking slag>
Prior to describing the steelmaking slag for fertilizer material according to the embodiment of the present invention in detail, a general steelmaking slag will be briefly described for comparison.

As steelmaking slag generally used for a fertilizer, the dephosphorization slag which is 1 type of steelmaking slag byproduced at the hot metal pre-processing process of a steel manufacturing process can be mentioned, for example. Dephosphorization slag is a slag containing phosphorus, which is by-produced by blowing in a gas such as oxygen as lime or iron oxide as a phosphorus removal agent to the molten metal to remove phosphorus contained in the molten metal. , A type of steelmaking slag.

The Iron and Steel Slag Association has published the composition of a representative steelmaking slag (converter slag) (http://www.slg.jp/character.html), and its representative composition is as follows: .
CaO: 45.8, SiO ₂ : 11.0, total iron: 17.4, MgO: 6.5,
Al ₂ O ₃ : 1.9, S: 0.06, P ₂ O ₅ : 1.7, MnO: 5.3 (each% by mass)

The steelmaking slag for fertilizer material according to the embodiment of the present invention, which will be described in detail below, is a kind of dephosphorization slag, but as described in detail below, when compared with the composition of a typical steelmaking slag as described above. It is characterized in that the content of P ₂ O ₅ and SiO ₂ is high and the content of total iron is low. In addition, the steelmaking slag for fertilizer material according to the present embodiment is characterized in that the content of the dissolvable boron is also higher than the composition of a typical steelmaking slag as described above.

<About steelmaking slag for fertilizer raw materials>
Below, steelmaking slag for fertilizer materials concerning this embodiment is explained in detail.
The steelmaking slag for fertilizer raw material according to the present embodiment is a steelmaking slag obtained by subjecting blast furnace hot metal to dephosphorizing treatment, containing Ca, P, Si, Mg, Fe. A predetermined amount of various elements such as Mn, B, S, Al, etc. is contained.

More specifically, the steelmaking slag for fertilizer raw material according to the present embodiment is, in mass%, P ₂ O ₅ : 2% or more and 8% or less, MnO: 3% or more and 10% or less, boron: 0.005% or more 0 .05% or less, total iron: 7% or more and less than 15%, CaO: 38% or more and 48% or less, SiO ₂ : 22% or more and 30% or less, sulfur: 0.1% or more and 0.6% or less, MgO: 1 % Or more and 8% or less, Al ₂ O ₃ : 0.5% or more and 3% or less. Moreover, the steelmaking slag for fertilizer raw materials which concerns on this embodiment may contain various impurities other than the said component.
Hereinafter, each component which steelmaking slag for fertilizer materials concerning this embodiment contains is explained in detail.

[CaO: 38% by mass or more and 48% by mass or less]
First, Ca will be described.
Ca is an essential fertilizer element for plants. In fertilizers and steelmaking slags, when the content of Ca is described, the content is expressed in terms of CaO of oxide, and hence the content of Ca is represented as CaO below.

CaO is a compound showing alkalinity and has an effect on improvement of acidic soil. If the content of CaO in steelmaking slag is less than 38% by mass, the alkalinity becomes weak, and the improvement of the acidic soil becomes insufficient in the acidic soil where iron overload disease is occurring, and it is contained in steelmaking slag. Is concerned that iron may exacerbate iron overload. On the other hand, when the CaO content in the steelmaking slag exceeds 48% by mass, the CaO content is too high, so P ₂ O ₅ is another component contained in the steelmaking slag for fertilizer material according to the present embodiment. And MnO, boron, total iron, sulfur, SiO ₂ , MgO, and Al ₂ O ₃ in order to make the total not more than 100%, any of the contents of these other components from the desired value It is not preferable because it will have to be lowered too. Moreover, it is preferable that the steel-making slag used in this embodiment can be stably supplied in large quantities, and it is preferable that it is what can be produced | generated by a normal iron-making process. From this viewpoint as well, the content of CaO of the steelmaking slag for fertilizer material according to the present embodiment is 38% by mass or more and 48% by mass or less. The content of CaO is preferably 39% by mass or more and 47% by mass or less, and more preferably 40% by mass or more and 46% by mass or less.

The content of CaO can be measured, for example, by fluorescent X-ray analysis.
Specifically, a plurality of measurement samples having known contents of CaO are prepared while changing the contents, and the fluorescence X-ray intensity derived from Ca of the measurement sample prepared by the fluorescent X-ray analyzer is measured. A calibration curve indicating the relationship between the CaO content and the fluorescent X-ray intensity is prepared in advance using the obtained Ca-derived fluorescent X-ray intensity and the content of CaO. Thereafter, for a sample whose content of CaO to be noticed is unknown, the fluorescent X-ray intensity derived from Ca is measured by a fluorescent X-ray analyzer, and the obtained fluorescent X-ray intensity and a calibration curve are used to obtain CaO. The content can be specified.

Here, after taking a sample as follows, the sample to which attention is paid is prepared in the following procedure, and fluorescent X-ray intensity is measured on the measurement conditions shown below.
That is, an analysis sample is set in a vibration mill (T-100 type manufactured by Kawasaki Heavy Industries, Ltd.), and the analysis sample is pulverized into powder (apparatus conditions: grinding time 30 seconds, 1000 rpm). The milled sample is subjected to distribution using a sieve of 212 μm mesh. Subsequently, 6 g of lithium tetraborate (flux), 0.3 g of a sample which has passed the sieve with the opening (212 μm), and about 2 cups of lithium iodide (peeling material) earpicks are put into a platinum dish, Melting is performed at 1,150 ° C. × 10 minutes × 3 to 4 times in a sampler to prepare glass beads. Similarly, the standard substance is processed into a glass bead. A calibration curve is created with a fluorescent X-ray analyzer (ZSX Primus II, manufactured by Rigaku Corporation), and determination of the sample passing through the sieve with the above-mentioned mesh size (212 μm) and confirmation analysis with a standard substance are carried out. This analysis method conforms to the JIS standard "JIS M 8205".

[SiO ₂ : 22 mass% or more and 30 mass% or less]
Subsequently, Si will be described.
Although Si is not an essential element of plants, it is a very important element for gramineaceous silicate plants such as rice, wheat and corn. Silica (SiO ₂ ) accounts for about 5% of the dry mass of rice plants. In fertilizers and steelmaking slags, when the content of Si is described, the content is expressed in terms of SiO ₂ of oxide, and hence the content of Si is hereinafter represented as SiO ₂ .

As mentioned earlier, the steelmaking slag for fertilizer material according to the present embodiment contains a large amount of SiO ₂ as compared with the composition of a typical steelmaking slag. The steelmaking slag for fertilizer raw material according to the present embodiment is effective for supplying Si to grasses and the like because it contains a large amount of available silicic acid effective for plants.

If the content of SiO ₂ of the steelmaking slag for fertilizer material according to the present embodiment is less than 22% by mass, the possibility that Si can not be sufficiently supplied to plants increases, which is not preferable. On the other hand, when the content of SiO ₂ exceeds 30% by mass, the CaO content also increases due to the restriction on the basicity to be described later, so other components contained in the steelmaking slag for fertilizer material according to the present embodiment In order to make the sum of the contents of MnO, boron, total iron, sulfur, SiO ₂ , MgO, and Al ₂ O _{3 not} more than 100%, the content of any of these other components is more than a desired value. It is not preferable because it will have to be lowered too. Thus, the fertilizer feedstock steel slag according to the present embodiment, the content of SiO ₂ is 30 mass% or less than 22 wt%. The content of SiO ₂ is preferably 23% by mass or more and 29% by mass or less, and more preferably 24% by mass or more and 28% by mass or less.

The content of SiO ₂ can be measured by, for example, fluorescent X-ray analysis.
Specifically, a plurality of measurement samples having a known content of SiO ₂ are prepared while changing the content, and Si-derived fluorescence X-ray intensity of the measurement sample prepared by the fluorescent X-ray analyzer is measured. The resulting a fluorescent X-ray intensity from Si was, and the content of SiO _2, using in advance a calibration curve showing the relationship between the content of SiO ₂ and the fluorescent X-ray intensity. Thereafter, for a sample whose content of SiO _{2 to be} noticed is unknown, the fluorescent X-ray intensity derived from Si is measured by a fluorescent X-ray analyzer, and the obtained fluorescent X-ray intensity and the calibration curve are used to determine SiO. The content of ₂ can be specified.

Here, the method of preparing the sample to be focused on and the measurement conditions of the fluorescent X-ray intensity are the same as in the case of CaO.

[Basicity (CaO content / SiO ₂ content): more than 1.5 and less than 2.2]
The steelmaking slag for a fertilizer raw material according to the present embodiment satisfies both the conditions regarding the CaO content and the SiO ₂ content as described above, and the basicity represented by (CaO content / SiO ₂ content) is , 1.5 over 2.2 or less.

In the steelmaking slag for fertilizer raw materials according to the present embodiment, since the content of CaO is 38 mass% or more and 48 mass% or less, the content of SiO ₂ is as follows when the basicity is considered in increments of 0.1: It is defined as
When basicity is 1.8: 21 mass% or more and 27 mass% or less When basicity is 1.7: 22 mass% or more and 28 mass% or less When basicity is 1.6: 24 mass% or more and 30 mass% When the basicity is 1.5 or less: 25% by mass or more and 32% by mass or less When the basicity is 1.4: 27% by mass or more and 34% by mass or less

As described above, the content of SiO ₂ (22% by mass or more and 30% by mass or less) defined in the steelmaking slag for fertilizer raw material according to the present embodiment has a basicity of 1.6 to 1 as described above. In the range of .7.

On the other hand, in the steelmaking slag for fertilizer material according to the present embodiment, the content of SiO ₂ is 22% by mass or more and 30% by mass or less. It becomes as follows.
When the basicity is 2.1: 46% by mass to 63% by mass When the basicity is 2.2: 48% by mass to 66% by mass When the basicity is 2.3: 51% by mass to 69% by mass Less than

In the steelmaking slag for fertilizer material according to the present embodiment, those having the above result within the range of the content of CaO (38 mass% or more and 48 mass% or less) defined have basicities of 2.1 to 2. It is a case where it becomes in the range of 2.

Therefore, it can be said that the basicity of more than 1.5 and 2.2 or less is the basicity which can satisfy the condition regarding the CaO content and the SiO ₂ content in the steelmaking slag for fertilizer raw material according to the present embodiment. .

The reasons for focusing on the basicity of around 1.4 to 1.8 and the basicity of around 2.1 to 2.3 in the above description are as follows.

The characteristics that most characterize the properties of the slag are basic. CaO is a component that is the main cause of the basicity of slag. In addition, in the actual iron making process, most of the basicity of the steelmaking slag obtained by the dephosphorization treatment of the hot metal pretreatment is about 1.5 to 1.8 and is easy to obtain. In addition, the inventors examined and examined that the basicity of slag which can realize elution of fertilizer active ingredients such as silicic acid, phosphoric acid, manganese, boron and the like in a more balanced manner is around 1.5 to 1.8. I found the results. Therefore, in the above description, attention was focused on the basicity of around 1.4 to 1.8.

On the other hand, as described above, in the actual iron making process, most of the basicity of steelmaking slag obtained by dephosphorizing treatment of hot metal pretreatment is about 1.5 to 1.8, and thus the basicity is 2 or more In order to produce a steelmaking slag, the operation for increasing the content of CaO or the operation for reducing the content of SiO ₂ is performed. Here, in the operation for increasing the content of CaO, the addition amount of lime added as a CaO source is increased, which is expensive. Therefore, by performing the operation to relatively low content of SiO _2, it is possible while suppressing an increase in cost to obtain a steel slag as described above. By using steelmaking slag having a basicity of 2 or more as a fertilizer raw material, more CaO can be contained in the steelmaking slag for fertilizer raw material. Since CaO is alkaline and exerts an effect on the improvement of acidic soil having a low pH, it is significant to realize the above basicity even if an operation different from the ordinary iron making process is performed. Therefore, in the above description, attention is focused on the basicities of 2.1 to 2.3.

In the steelmaking slag for fertilizer raw material according to the present embodiment, when the basicity is 1.5 or less, the content of CaO becomes relatively low from the viewpoint of use for fertilizer raw material, so improvement of acidic soil is achieved. It is not preferable because the effect is weak. On the other hand, in the steelmaking slag for fertilizer material according to the present embodiment, when the basicity exceeds 2.2, when considering from the viewpoint of use for fertilizer material, fertilization with more CaO than CaO necessary for improvement of acidic soil is applied. It is not preferable because it causes an increase in the cost of lime added as a CaO source. Therefore, in the steelmaking slag for a fertilizer material according to the present embodiment, the basicity is set to more than 1.5 and not more than 2.2. By setting the basicity to more than 1.5 and not more than 2.2, it is possible to suppress the cost of lime added to increase the appropriate improvement effect of CaO content and CaO content from the viewpoint of fertilizer raw materials. . The basicity is preferably 1.6 or more and 2.1 or less, more preferably 1.6 or more and 2.0 or less.

In addition, 2CaO · SiO ₂ -3CaO · P ₂ O ₅ solid solution and FeO-MnO-CaO-SiO are produced in the steelmaking slag manufactured by adjusting the basicity to be more than 1.5 and not more than 2.2. _{The two-} system solid solution tends to be formed together. In addition, as described in detail below, in the production process of steelmaking slag, by quenching when solidifying the slag, the above-described two types of solid solutions are more easily formed. As described in detail below, these solid solutions have both of these solid solutions as steelmaking slag for fertilizer raw materials in order to promote the elution of phosphoric acid, manganese and boron in addition to silicic acid. preferable.

[P ₂ O ₅ : 2% by mass or more and 8% by mass or less, proportion of soluble P ₂ O ₅ : 50% or more]
Next, P will be described.
P is an essential element of plants together with N and K. P is an element necessary for genes such as DNA and RNA, energy metabolites such as ATP, and constituents of cell membranes. P is an element that acts on the root growth point and has an effect on root growth. When P is insufficient, root growth is suppressed.

In fertilizer and steelmaking slag, when expressing the content of P, the content is expressed in terms of P ₂ O ₅ in the oxide, so in the following, the content of P as P ₂ O ₅ Show.

In soil that is acidic and in conditions where Al and Fe are ionized and easily eluted, P is insolubilized as aluminum phosphate (AlPO ₄ ) or iron phosphate (FePO ₄ ), and plant roots are P May not be able to absorb phosphate ion (PO ₄ ^3- ) containing The steelmaking slag for fertilizer raw material according to the present embodiment contains CaO and MgO and is alkaline, so the acidic soil is improved to prevent ionization of Al and Fe from the soil to prevent elution. It is possible to elute P gradually as phosphate ion (PO ₄ ^3- ).

In the steelmaking slag for fertilizer material according to the present embodiment, P is mainly present in the composition of Ca ₂ SiO ₄ -Ca ₃ (PO ₄ ) ₂ . In the soil, P is gradually eluted as PO ₄ ^3- , together with Ca and Si, from the fertilizer containing the steelmaking slag for fertilizer material according to the present embodiment. Therefore, it is possible to gradually supply P to a plant without being insolubilized by Al or Fe in a long period of several months equivalent to one crop of rice or the like.

In the fertilizer feedstock steel slag according to the present embodiment, the content of P ₂ O ₅ is in the case is less than 2 mass%, it is impossible to reliably achieve the above effects. Therefore, in the steelmaking slag for a fertilizer material according to the present embodiment, the content of P ₂ O ₅ is 2% by mass or more.

On the other hand, the fertilizer feedstock steel slag according to the present embodiment, when the content of P ₂ O ₅ is more than 8% by weight, in view from the perspective of a fertilizer feedstock, the P ₂ O ₅ in the soil, the other It is not preferable because it may be oversupplied without balance with nitrogen and potassium, which are the three major elements of fertilizer. Therefore, in the steelmaking slag for a fertilizer material according to the present embodiment, the content of P ₂ O ₅ is 8% by mass or less.

In addition, in steelmaking slag for fertilizer materials according to the present embodiment, the content of P ₂ O ₅ is preferably 3% by mass to 8% by mass, and more preferably 3% by mass to 6% by mass is there.

In the fertilizer control method, the content of water-soluble P ₂ O ₅ is specified as 3 mass% or more as mineral phosphate phosphate fertilizer. The steelmaking slag for fertilizer raw material according to the present embodiment does not necessarily meet the specification of mineral phosphate phosphoric acid fertilizer, but from the above reasons, the fertilizer effect of P can be expected. In the steelmaking slag for fertilizer raw material according to the present embodiment, when the content of P ₂ O ₅ is 2% by mass or more, the content of the semisoluble P ₂ O ₅ corresponds to approximately 1.0% by mass or more. .

On the other hand, from the rather soluble P ₂ O _5, eluting with 2% aqueous citric acid solution, towards the soluble P ₂ O ₅ eluting with ammonium citrate aqueous solution of neutral (page ether Man ammonium citrate solution) is actually plant It is known to be a more suitable value for P ₂ O ₅ that can be absorbed from roots. The steelmaking slag for fertilizer raw material according to the present embodiment is one that succeeded in raising the ratio of soluble P ₂ O ₅ to 50% or more of P ₂ O ₅ contained in the slag by controlling the composition and structure of the slag. is there. That is, with reference to the method of manufacturing a fertilizer feedstock steel slag as described in detail below, by the production of fertilizers for steelmaking slag, the mass of the soluble P ₂ O ₅ in P ₂ O ₅ contained in slag The proportion can be 50% or more. The upper limit value of the mass ratio of soluble P ₂ O _{5 in} P ₂ O ₅ contained in the slag is not particularly limited, and the higher the higher, the better, but the results of actually producing and analyzing a large number of steelmaking slag samples In view of the above, it can not be made 100%, and the upper limit is about 85%. The mass ratio of soluble P ₂ O _{5 in} P ₂ O ₅ contained in the slag is preferably 60% or more, more preferably 70% or more.

The content of P ₂ O ₅ can be measured, for example, by fluorescent X-ray analysis.
Specifically, a plurality of measurement samples having known contents of P are prepared while changing the contents, and P-derived fluorescence X-ray intensities of the prepared measurement samples are measured by a fluorescent X-ray analyzer. Using the obtained P-derived fluorescent X-ray intensity and the converted amount of P ₂ O ₅ calculated from the P content, the relationship between the converted amount of P ₂ O ₅ and the fluorescent X-ray intensity is obtained. A calibration curve to be shown is prepared in advance. Thereafter, for a sample whose content of P to be noticed is unknown, the fluorescent X-ray intensity derived from P is measured by a fluorescent X-ray analyzer, and the obtained fluorescent X-ray intensity and a calibration curve are used to determine P ₂ The content of O ₅ can be specified.

Here, the method of preparing the sample to be focused on and the measurement conditions of the fluorescent X-ray intensity are the same as in the case of CaO.

Also, the content of soluble P ₂ O ₅ can be measured by ammonium vanadomolybdate spectrophotometric method using a Petermann ammonium citrate solution. Using content and the content of soluble _P 2 _{O 5} of the measured _P 2 _{O 5,} it can be calculated mass percentage of soluble _P 2 _{O 5} in P 2 _{O 5.}

[MgO: 1% by mass or more and 8% by mass or less]
Subsequently, Mg will be described.
Mg is an element necessary for plants and is considered as a secondary element.

In general, the MgO content of steelmaking slag is considerably lower than the CaO content. Mg contained in steelmaking slag is mainly attributable to Mg added from the sintering process and Mg eluted from refractory bricks of the furnace wall of the converter. In fertilizers and steelmaking slags, when the content of Mg is expressed, the content is expressed in terms of MgO of oxide, and hence the content of Mg as MgO is hereinafter indicated.

MgO is alkaline and has the effect of improving acidic soil with CaO. In the steelmaking slag for a fertilizer raw material according to the present embodiment, when the content of MgO is less than 1% by mass, the above-described improvement effect of the acidic soil can not be exhibited. On the other hand, from the viewpoint of fertilizer raw materials, the ideal lime / magnesia ratio is about 2.5-6. In the steelmaking slag for fertilizer raw material according to the present embodiment, the CaO content is as high as 38% to 48%, so in order to satisfy the above-mentioned lime / bodiment ratio, for example, the lime / bodiment ratio is the largest 6 Even in the case of the above, the content of bitter clay is 6.3% to 8%. However, it is difficult to make the MgO content to exceed 8% by mass unless adding an additional MgO source in an actual iron making process. Therefore, in steelmaking slag for fertilizer materials concerning this embodiment, MgO content shall be 1 mass% or more and 8 mass% or less. The content of MgO is preferably 2% by mass to 8% by mass, and more preferably 3% by mass to 8% by mass.

The content of MgO can be measured, for example, by fluorescent X-ray analysis.
Specifically, a plurality of measurement samples having a known content of Mg are prepared while changing the content, and the fluorescent X-ray intensity derived from Mg of the measurement sample prepared by the fluorescent X-ray analyzer is measured. A calibration curve showing the relationship between the converted amount of MgO and the fluorescent X-ray intensity is created in advance using the obtained Mg-derived fluorescent X-ray intensity and the converted amount of MgO calculated from the content of Mg Keep it. Thereafter, for a sample whose content of Mg to be noticed is unknown, the fluorescent X-ray intensity derived from Mg is measured by a fluorescent X-ray analyzer, and the obtained fluorescent X-ray intensity and a calibration curve are used to The content can be specified.

Here, the method of preparing the sample to be focused on and the measurement conditions of the fluorescent X-ray intensity are the same as in the case of CaO.

[Total iron: 7% by mass or more and less than 15% by mass]
Subsequently, Fe will be described.
Fe is a trace element necessary for plants, and iron-containing substances are used as special fertilizers. However, in acidic soils, Fe is also an element that can be harmful to plants as it can cause iron overload in plants.

The steelmaking slag for fertilizer raw material according to the present embodiment is alkaline because it contains CaO at 38 mass% or more and 48 mass% or less and contains MgO at 1 mass% or more and 8 mass% or less. As described below, since the total iron content is reduced to a relatively low level of 7% by mass to less than 15% by mass, Fe as a trace element is present even in soils that may cause iron overload in acidic soils. Can be supplied to plants.

A feature of the fertilizer containing the steelmaking slag for fertilizer material according to the present embodiment is that it has a large bulk specific gravity and is characterized by being able to elute each element which has a fertilizer effect for a long time without remaining due to rain water. Fe is an important element also in order to raise the bulk specific gravity of the fertilizer containing steelmaking slag for fertilizer materials which concerns on this embodiment.

Fe is an element unavoidably contained in various steelmaking slags. In the steelmaking slag for fertilizer raw material according to the present embodiment, when the content of total iron is less than 7% by mass, the bulk specific gravity decreases, and the fertilizer containing the steelmaking slag for fertilizer raw material according to the present embodiment is washed away by rainwater You are more likely to On the other hand, when the content of total iron is 15% by mass or more, the possibility of causing iron overload in plants in acidic soil is increased, which is not preferable. Therefore, the total iron content of the steelmaking slag for fertilizer material according to the present embodiment is 7% by mass or more and less than 15% by mass. The content of total iron is preferably 8% by mass or more and 14% by mass or less, and more preferably 9% by mass or more and 13% by mass or less.

When the steelmaking slag for fertilizer raw material according to the present embodiment is analyzed by an X-ray diffractometer, a peak of a mineral attributed to the FeO-CaO-SiO ₂ system is observed. On the other hand, when the steelmaking slag for fertilizer material according to the present embodiment is immersed in water for a long period of time and the structure is observed with an electron probe micro analyzer (EPMA), the concentration of Fe and Mn in the overlapping portion exists. There is evidence of a decline. From this, it is considered that the dissolution of Mn into the soil together with Fe is further promoted when the FeO-MnO-CaO-SiO ₂ -based solid solution in which MnO and FeO are solid-solved is formed. Such an oxidation state of Fe is realized by producing steelmaking slag for fertilizer material according to the manufacturing method of steelmaking slag for fertilizer material as described in detail below. In addition, the name of the solid solution in the present embodiment clearly indicates the main chemical components, and may include components that are not explicitly specified. For example, the FeO-MnO-CaO-SiO ₂ -based solid solution includes that in which MgO is a solid solution.

In addition, according to the manufacturing method of steelmaking slag for fertilizer materials as detailed below, the steelmaking slag for fertilizer materials manufactured by manufacturing steelmaking slag for fertilizer materials is a general converter process. As compared with the steelmaking slag to be manufactured, the content of total iron becomes relatively low, and the above-mentioned range of the content is realized, and the above-described oxidation state of Fe is realized.

The total iron content can be measured, for example, by fluorescent X-ray analysis.
Specifically, a plurality of measurement samples having a known content of total iron are prepared while changing the content, and Fe-derived fluorescence X-ray intensity of the prepared measurement sample is measured by a fluorescent X-ray analyzer. A calibration curve indicating the relationship between the total iron content and the fluorescent X-ray intensity is prepared in advance using the obtained Fe-derived fluorescent X-ray intensity and the total iron content. Thereafter, for a sample whose content of total iron to be noticed is unknown, the X-ray fluorescence intensity derived from Fe is measured by a fluorescent X-ray analyzer, and the obtained X-ray fluorescence intensity and a calibration curve are used to total The iron content can be identified.

Here, the method of preparing the sample to be focused on and the measurement conditions of the fluorescent X-ray intensity are the same as in the case of CaO.

[MnO: 3% by mass or more and 10% by mass or less, the proportion of non-soluble manganese: 80% or more]
Subsequently, Mn will be described.
Mn is also an element that has a fertilizer effect on plants as a trace element. In fertilizers and steelmaking slags, when the content of Mn is described, the content is expressed in terms of MnO of oxide, and hence the content of Mn is hereinafter referred to as MnO.

In the steelmaking slag for fertilizer raw material according to the present embodiment, when the content of MnO is less than 3% by mass, since the content of MnO is small, the fertilizer containing the steelmaking slag for fertilizer raw material according to the present embodiment The dissolution of Mn is not sufficient, and the fertilizer effect of Mn can not be exhibited. On the other hand, when the content of MnO exceeds 10% by mass, this is not preferable because it causes plants to generate an excess of manganese disease particularly in an acidic soil. Therefore, in steelmaking slag for fertilizer materials concerning this embodiment, content of MnO shall be 3 mass% or more and 10 mass% or less. The content of MnO is preferably 4% by mass to 9% by mass, and more preferably 5% by mass to 8% by mass.

Further, as described above, the 2CaO · SiO ₂ -3CaO · P ₂ O ₅ solid solution and the FeO-MnO-CaO-SiO ₂ -based solid solution are both formed in the steelmaking slag for fertilizer material according to the present embodiment. In addition, the elution of Mn can be further promoted, and the elution of silicic acid, phosphoric acid and boron can be promoted.

Plants are known to secrete organic acids from the roots, and it is an index to consider that light-soluble manganese, which is manganese eluted in 2% aqueous citric acid solution, as manganese available to plants. The steelmaking slag for fertilizer raw materials which concerns on this embodiment succeeds in making 80% or more into a water-soluble MnO among MnO contained in steelmaking slag by composition and structure control. That is, according to the method for producing steelmaking slag for fertilizer raw material as described in detail below, by producing steelmaking slag for fertilizer raw material, the mass ratio of fusible MnO in MnO contained in the slag is 80% It can be more than. The upper limit value of the mass ratio of poorly soluble MnO in MnO contained in the slag is not particularly limited, and the higher the higher, the better, but it is 100% in view of the results of analysis of many steelmaking slag samples actually produced The upper limit is about 95%. The mass ratio of the soluble MnO in MnO contained in the slag is preferably 85% or more, more preferably 90% or more.

The content of MnO can be measured, for example, by fluorescent X-ray analysis.
Specifically, a plurality of measurement samples having a known content of Mn are prepared while changing the content, and the fluorescent X-ray intensity derived from Mn of the measurement sample prepared by the fluorescent X-ray analyzer is measured. A calibration curve showing the relationship between the converted amount of MnO and the fluorescent X-ray intensity is prepared in advance using the obtained Mn-derived fluorescent X-ray intensity and the converted amount of MnO calculated from the content of Mn. Keep it. Thereafter, for a sample whose content of Mn to be noticed is unknown, the fluorescent X-ray intensity derived from Mn is measured by a fluorescent X-ray analyzer, and the obtained fluorescent X-ray intensity and a calibration curve are used to obtain MnO The content can be specified.

Here, the method of preparing the sample to be focused on and the measurement conditions of the fluorescent X-ray intensity are the same as in the case of CaO.

In addition, the content of the soluble MnO is defined by the elution with 2% citric acid aqueous solution and the flame atomic absorption method, the fertilizer specified by the independent administrative corporation Food and Agricultural Materials Inspection Center (FAMIC) It can be measured by using the method described in the iso test method (2016). The mass ratio of the semisoluble MnO in MnO can be calculated using the measured content of MnO and the content of the semisoluble MnO.

[Boron: 0.005% by mass or more and less than 0.05% by mass, the proportion of the miscible boron: 95% or more]
Subsequently, boron will be described.
Boron is a trace element necessary for plants, and boron deficiency is known to cause plants to have boron deficiency. Boron is an element necessary for the synthesis of plant cell walls.

On the other hand, it is known that plants may have an excess of boron if the soil's boron content exceeds 5 mg / kg. The boron content of 5 mg / kg is a very low value. Commercially available boron-containing fertilizers include, for example, borate fertilizers (35% or more of fusible boron), boron fertilizers (about 24% of miscible boron), mixed trace element fertilizers (FTE) Although there is soluble boron (5 to 9%), it is feared that excessive use of these fertilizers may cause excess boron, since they all contain a large amount of boron. It is not easy to apply these commercially available fertilizers to the soil to reduce the boron content of the soil to 5 mg / kg or less.

For example, when a fertilizer with a boron content of 5% is applied to 1 kg of soil, assuming that the soil does not contain boron, to make the soil a boron content of 5 mg / kg or less, a small amount of 100 mg or less of fertilizer is uniform It is necessary to mix it with the soil and apply it. Therefore, at general application rates, there is a great concern that boron is excessively applied. In order to uniformly apply a small amount of fertilizer containing a large amount of boron, it is conceivable to apply it by dissolving or dispersing it in water, but it is considered that conventional fertilizers are likely to be washed away by rain water and the like. Therefore, in order to optimally supply boron to the soil, it is considered that a low content of boron and a type of fertilizer that does not run away are preferable.

In steelmaking slag for fertilizer materials concerning this embodiment, when content of boron is less than 0.005 mass% (= 50 mg / kg), fertilizer containing steelmaking slag for fertilizer materials concerning this embodiment to soil with respect to soil Even if it applies, since the supply amount of boron is small, the fertilizer effect of boron to a plant can not be exhibited. On the other hand, steelmaking slags in which the content of boron is 0.05% by mass or more can not be obtained in a normal iron making process, and a boron source such as borax is additionally added to increase the boron content. Is not preferable because it causes cost increase. In addition, the steelmaking slag for fertilizer material according to the present embodiment has a boron content of less than 0.05% by mass because the ratio of hexasoluble boron in the boron content is very high compared to conventional boron-based fertilizers. Also, it has the same boron supply ability as conventional boron-based fertilizers. Therefore, in steelmaking slag for fertilizer materials concerning this embodiment, content of boron is made into 0.005 mass% or more and less than 0.05 mass%. The content of boron is preferably 0.01% by mass or more and 0.05% by mass or less, and more preferably 0.02% by mass or more and 0.05% by mass or less.

As described above, plants are known to secrete organic acids from their roots, and it is considered that copper soluble boron, which is an eluant dissolved in 2% aqueous citric acid solution, is considered as boron usable by plants. It becomes one index. The steelmaking slag for fertilizer raw materials according to the present embodiment has a basicity which is a ratio of the content of CaO to SiO ₂ of more than 1.5 and not more than 2.2, and the temperature at the time of molten slag formation and the cooling method at the time of slag solidification Control the structure to create boron as a compound in which, for example, a portion of SiO _{2 in} the compound of SiO ₂ is replaced by B ₂ O ₃ , etc. Was successfully achieved, and 95% or more of the boron contained in the steelmaking slag could be made soluble in boron. That is, according to the method for producing steelmaking slag for fertilizer raw material as described in detail below, by producing steelmaking slag for fertilizer raw material, 95% of the mass ratio of soluble boron in boron contained in the slag is It can be more than. By increasing the proportion of the soluble boron, a high fertilization effect can be obtained despite the low content of boron contained in the steelmaking slag for fertilizer material.

The boron content can be measured, for example, by ICP emission analysis.
Specifically, 0.5 g of a sample and a reagent (2 g of sodium carbonate, 3 g of sodium peroxide) are put in a Ni crucible and alkali melting (burner heating) is performed. Place the alkali-melted Ni crucible in a beaker, add water and hydrochloric acid (1: 9) to dissolve the Ni crucible contents, take out the Ni crucible and heat the beaker to dissolve the sample. The resulting dissolved sample is introduced into a high frequency inductively coupled plasma (apparatus: Hitachi High-Tech Science SPS 3100), and the emission of boron is measured at a wavelength of 249.753 nm to quantify boron. This analysis method is a method in accordance with JIS A 5011-3 Appendix A.

In addition, the content of the soluble boron was determined by the elution with a 2% aqueous solution of citric acid and the azomethine H method, which was defined by the independent administrative corporation Food and Agricultural Materials Inspection Center (FAMIC), etc. It can be measured by using the method described in the test method (2016). Using the measured content of boron and the content of soluble boron, it is possible to calculate the mass ratio of the soluble boron in boron.

[Sulfur: 0.1% by mass to 0.6% by mass]
Subsequently, sulfur will be described.
Sulfur is an element necessary for biosynthesis of sulfur-containing amino acids such as cysteine and methionine, and further for biosynthesis of protein, and is an element essential for the growth of green onion, onion, garlic and the like.

When the sulfur content of the steelmaking slag for fertilizer raw material according to the present embodiment is less than 0.1 mass%, even if fertilizer using the steelmaking slag for fertilizer raw material according to the present embodiment is applied to the soil, the supply of sulfur Due to the small amount, it may not be possible to exert the fertilizer effect of sulfur on plants. On the other hand, when the sulfur content of the steelmaking slag for fertilizer material according to the present embodiment exceeds 0.6% by mass, the sulfur supplied from the fertilizer causes hydrogen sulfide to be generated in the soil to cause root rot, etc. Problems can occur. Therefore, the sulfur content of the steelmaking slag for a fertilizer material according to the present embodiment is set to 0.1% by mass or more and 0.6% by mass or less. The sulfur content is preferably 0.2% by mass or more and 0.6% by mass or less, and more preferably 0.3% by mass or more and 0.6% by mass or less.

The sulfur content can be measured by, for example, alkali melting and ICP emission analysis.
Specifically, 0.5 g of a sample and a reagent (2 g of sodium carbonate, 3 g of sodium peroxide) are put in a Ni crucible and alkali melting (burner heating) is performed. Place the alkali-melted Ni crucible in a beaker, add water and hydrochloric acid (1: 9) to dissolve the Ni crucible contents, take out the Ni crucible and heat the beaker to dissolve the sample. The resulting dissolved sample is introduced into a high frequency inductively coupled plasma (apparatus Hitachi High-Tech Science SPS 3100), and the emission of sulfur is measured at a wavelength of 182.036 nm to quantify sulfur. This analysis method is a method in accordance with JIS A 5011-3 Appendix A.

[Al ₂ O ₃ : 0.5 to 3% by Mass]
Subsequently, Al will be described.
In fertilizers and steelmaking slag, when expressing the content of Al, the content is expressed in terms of Al ₂ O ₃ in the oxide, so hereinafter, the content of Al is expressed as Al ₂ O ₃ .

Since Al ^forms aluminum ion Al ^{3 +} in acidic soil and binds to phosphate ion PO ₄ ³⁻ , it has an action of suppressing plant roots to absorb P. Therefore, the content of Al ₂ O ₃ in the steelmaking slag for a fertilizer material according to the present embodiment is preferably as low as possible.

When the content of Al ₂ O _{3 in} the steelmaking slag for fertilizer raw material according to the present embodiment exceeds 3% by mass, from the fertilizer containing the steelmaking slag for fertilizer raw material according to the present embodiment for the above reasons. It suppresses the elution of P. On the other hand, when dephosphorizing blast furnace hot metal, Al ₂ O ₃ is unavoidably mixed in the slag, so the content of Al ₂ O ₃ should be 0.5 mass% or less. Have difficulty. Thus, the fertilizer feedstock steel slag according to the present embodiment, the content of _Al 2 _{O 3,} and 3 wt% or less than 0.5 wt%. The content of Al ₂ O ₃ is preferably 0.5% by mass or more and 2.5% by mass or less, and more preferably 0.5% by mass or more and 2% by mass or less.

The content of Al ₂ O ₃ can be measured, for example, by fluorescent X-ray analysis.
Specifically, a plurality of measurement samples having a known content of Al are prepared while changing the content, and the fluorescent X-ray intensity derived from Al of the measurement sample prepared by the fluorescent X-ray analyzer is measured. The relationship between the converted amount of Al ₂ O ₃ and the fluorescent X-ray intensity is calculated using the obtained fluorescent X-ray intensity derived from Al and the converted amount of Al ₂ O ₃ calculated from the content of Al. A calibration curve to be shown is prepared in advance. Thereafter, for a sample whose content of Al to be noticed is unknown, the fluorescent X-ray intensity derived from Al is measured by a fluorescent X-ray analyzer, and the obtained fluorescent X-ray intensity and a calibration curve are used to determine Al ₂ The content of O ₃ can be specified.

Here, the method of preparing the sample to be focused on and the measurement conditions of the fluorescent X-ray intensity are the same as in the case of CaO.

[Bulk specific gravity: 1.9 or more and 2.8 or less]
The steelmaking slag for fertilizer raw materials which concerns on this embodiment becomes 1.9 or more and 2.8 or less in bulk specific gravity (more specifically, loose bulk specific gravity) by having the above composition. If the bulk specific gravity is less than 1.9, it is not preferable because a large amount of rainfall increases the possibility of fertilizer runoff. On the other hand, when the bulk specific gravity exceeds 2.8, the person handling the fertilizer comes to feel heavy, which is not preferable. The bulk specific gravity of the steelmaking slag for a fertilizer material according to the present embodiment is preferably 2.0 or more and 2.7 or less, more preferably 2.1 or more and 2.6 or less.

In addition, it is possible to measure the bulk specific gravity of steelmaking slag for fertilizer raw materials by the following methods, for example. That is, bulk specific gravity (loose bulk specific gravity) can be determined as a value obtained by dividing the mass lightly packed in a fixed volume by the volume. Here, the slag used for the measurement has a particle size corresponding to MS-25 specified in JIS A5015, and the unit volume mass (= bulk specific gravity) is measured according to JIS A1104.

[About the structure of steelmaking slag for fertilizer raw material]
The steelmaking slag for fertilizer raw material according to the present embodiment preferably contains, as its structure, both 2CaO · SiO ₂ -3CaO · P ₂ O ₅ solid solution and FeO-MnO-CaO-SiO ₂ -based solid solution. These solid solutions can be formed more efficiently by quenching the slag when solidifying the slag in the molten state at the time of production of the steelmaking slag for fertilizer material, as described below.

In soil, in addition to calcium and silicic acid, phosphoric acid elutes more efficiently from 2CaO · SiO ₂ -3CaO · P ₂ O ₅ solid solution. Further, in the soil, iron and manganese are more efficiently eluted from the FeO-MnO-CaO-SiO ₂ -based solid solution. Therefore, the steelmaking slag for fertilizer materials according to the present embodiment contains these solid solutions together as its structure, thereby more efficiently achieving a fertilizer effect such as calcium, silicic acid, phosphoric acid, iron and manganese in the soil. It becomes possible to elute the element which it has. Further, the fertilizer feedstock steel slag is produced through a production method as described below, although the reason is not clear, since the SiO ₂ of a portion of these in solid solution is easily replaced with B ₂ O _3, these solid solutions It becomes possible to elute also about boron by containing together.

The presence of the 2CaO · SiO ₂ -3CaO · P ₂ O ₅ solid solution and the FeO-MnO-CaO-SiO ₂ -based solid solution can be confirmed by the following method.

For example, after the steelmaking slag for fertilizer material according to the present embodiment is made into powder, the X-ray source is Co-Kα (λ = 1. 1) by a general X-ray diffractometer (eg, Rigaku X-ray diffractometer SmartLab). 7902 Å), X-ray source load power (tube voltage / tube current) is 5.4 kW (40 kV / 135 mA), detector is a scintillation counter, scan rate is 1.5 ° / min, concentration method (θ-2θ) X-ray diffraction is carried out by measurement), and 2CaO · SiO ₂ crystal, FeO · CaO · SiO ₂ crystal, etc. are confirmed. Further, the steelmaking slag for fertilizer raw material according to the present embodiment is embedded in a known resin such as an epoxy resin, and then ground and polished to expose a smooth cross section of the steelmaking slag for fertilizer raw material, and a general EPMA device Each element distribution of the slag structure observed on the cross section at an accelerating voltage of 15 kV is mapped using (for example, JXA-8100 manufactured by JEOL Ltd.). In addition, the slag structure in which Ca, Si, O and P are observed together and the slag structure in which Fe, Mn, Ca, Si and O are observed together in the measurement area with a diameter of 100 μm, and EPMA of each element It is possible to confirm that the 2CaO · SiO ₂ -3CaO · P ₂ O ₅ solid solution or the FeO-MnO-CaO-SiO ₂ -based solid solution is present by analyzing the count by the ZAF method and semi-quantifying it.

[About the particle size of steelmaking slag for fertilizer raw material]
In this embodiment, it is possible to use suitably as a raw material of a fertilizer by adjusting the above-mentioned steelmaking slag for fertilizer materials to an appropriate particle size by grinding etc. For grinding the steelmaking slag for such fertilizer material, known means such as a jaw crusher, a hammer crusher, a rod mill, a ball mill, a roll mill and a roller mill can be used, for example.

The steelmaking slag for fertilizer material preferably has a particle size of less than 5 mm, and more preferably has a particle size of less than 600 μm, by the above-mentioned pulverizing method. In addition, these particle sizes are particle sizes by the sieving method using the sieve prescribed | regulated to JISZ8801. If the particle size of the steelmaking slag for fertilizer material is 5 mm or more, the specific surface area of the steelmaking slag for fertilizer material may be too small, and the elution efficiency of each fertilizer effect element may be low. Further, when the particle diameter of the steelmaking slag for fertilizer material is less than 600 μm, the specific surface area of the steelmaking slag for fertilizer material becomes larger, and it becomes possible to further enhance the elution efficiency of each fertilizer effect element.

Further, in the steelmaking slag for fertilizer material according to the present embodiment, it is preferable that the mass ratio of the particle diameter of less than 600 μm be 60% or more with respect to the total mass. By setting the mass ratio of the particle diameter to less than 600 μm to 60% or more, the elution efficiency of each fertilizer effect element can be further enhanced. More preferably, the mass ratio of the particle diameter of less than 600 μm is 80% or more.

In the above, steelmaking slag for fertilizer materials concerning this embodiment was explained in detail.

<About the manufacturing method of steelmaking slag for fertilizer materials>
Then, the manufacturing method of steelmaking slag for fertilizer materials concerning this embodiment is explained in detail. The steelmaking slag for fertilizer raw materials which concerns on this embodiment is manufactured by performing a specific dephosphorization process which is demonstrated below with respect to a blast furnace hot metal.

As described above, the steelmaking slag for fertilizer material according to the present embodiment is the same as the steelmaking slag for fertilizer material according to the present embodiment, except for (1) a converter type pot (in the furnace from the freeboard / furnace opening corresponding to the length from The blast furnace hot metal is injected so that the void ratio represented by the in-furnace height corresponding to the length to the bottom is 0.5 or more and 0.9 or less, and (2) the blast furnace hot metal in the converter pot is On the other hand, manganese ore, manganese-containing decarburized slag, and / or ferromanganese are added, and (3) lance inserted from the blast furnace hot metal to the blast furnace hot metal, quick lime having an average particle size of 1 mm or less It is manufactured by blowing in calcium carbonate and oxygen, forming slag at 1300 ° C. or more and 1400 ° C. or less, and performing dephosphorization treatment. At this time, the slag basicity represented by (CaO content / SiO ₂ content) is more than 1.5 and 2.2 or less, and the MnO content in the slag is 3% by mass or more and 10% by mass or less Manufactured to be

[1: Blast furnace hot metal injection process]
The blast furnace hot metal injection process shown to said (1) is a process of inject | pouring the produced | generated blast furnace hot metal into a converter-type pan. When the blast furnace hot metal is injected into a converter-type pan, if the void ratio represented by (free board / in-furnace height) is less than 0.5, the free board becomes too small, resulting in the hot metal surface Since the void existing above is too narrow, it is difficult to sufficiently form blast furnace hot metal, which is not preferable because the dephosphorization reaction can not be sufficiently advanced. On the other hand, when the void ratio represented by (free board / in-furnace height) exceeds 0.9, the amount of hot metal to be dephosphorized is not preferable because it becomes inefficient. Since only a small amount of blast furnace hot metal is injected therein, the operation efficiency is lowered and the productivity is lowered. The void ratio represented by (free board / in-furnace height) is preferably 0.5 or more and 0.8 or less, and more preferably 0.6 or more and 0.8 or less.

[2: Additive injection process]
In the additive charging step shown in the above (2), at least any of manganese ore, manganese-containing decarburized slag, and ferromanganese, with respect to the blast furnace hot metal in the converter-type pan, containing MnO in the desired slag It is the process of introducing so that it may become amount (namely, MnO content 3 to 10 mass% in slag). Here, among the above-mentioned additives, it is not particularly limited which additive is added in what amount, and it may be appropriately determined according to the desired content of MnO in the slag.

[3: Dephosphorization process]
In the dephosphorization treatment step shown in the above (3), a calcium source and oxygen are blown into the blast furnace hot metal in which the MnO content is adjusted, and slag is formed at a predetermined temperature, thereby dephosphorizing the blast furnace hot metal Process.

Here, as a calcium source used for the dephosphorization treatment, at least one of quick lime and calcium carbonate having an average particle diameter of 1 mm or less is used. In addition, quick-lime with an average particle diameter of 1 mm or less, and calcium carbonate can be obtained using the industrial sieve prescribed | regulated to JISZ8801. When using quicklime as a calcium source, when the average particle diameter exceeds 1 mm, it is not preferable because unreacted quicklime may remain. Moreover, when the average particle diameter of quick lime and calcium carbonate exceeds 1 mm, the lance may be damaged by the blowing, and the life of the lance may be shortened, which is not preferable. Here, the average particle diameter of quick lime and calcium carbonate means a particle diameter having an integrated mass% value of 50% in the particle size distribution passing through the industrial sieve defined in JIS Z8801. The amount of such calcium source blown is such that the desired basicity (i.e., more than 1.5 and not more than 2.2) is obtained at the end of the dephosphorization step.

Moreover, the temperature of the slag at the time of forming shall be 1300 degreeC or more and 1400 degrees C or less. If the temperature of the slag is less than 1300 ° C., it is not preferable because the dephosphorization reaction does not proceed. On the other hand, when the temperature of the slag exceeds 1400 ° C., it is not preferable because there is a possibility of re-phosphorization in which phosphorus dissolves back into the molten steel. The temperature of the slag at the time of forming is preferably 1310 ° C. or more and 1390 ° C. or less, and more preferably 1320 ° C. or more and 1380 ° C. or less. The temperature of the slag can be measured using a thermocouple or an optical pyrometer.

The above dephosphorization treatment is carried out so that the slag basicity is more than 1.5 and 2.2 or less, and the MnO content in the slag is 3 mass% or more and 10 mass% or less, and the slag base is When the degree and the MnO content fall within the ranges as described above, the dephosphorization treatment ends.

By carrying out the above-described dephosphorization treatment, the components of the manufactured steelmaking slag have the characteristics as described above, and the specific gravity thereof also falls within the above-mentioned range.

It is preferable that (4) slag solidification process and (5) slag crushing process which are demonstrated below are implemented after the dephosphorization process demonstrated above.

[4: slag solidification process]
The slag solidification step shown in the above (4) is a step of solidifying the molten slag after the dephosphorization treatment by a predetermined method.

The slag solidification step may be, for example, a step of pouring the molten slag after the dephosphorization treatment into a dish-shaped heat-resistant container and rapidly cooling to solidify it. At this time, in order to cool the molten slag more effectively, the molten slag is preferably spread thinly in a dish-shaped heat-resistant container, and water is sprayed to the thin spread molten slag. Preferably, the molten slag is rapidly cooled (quenched).

Moreover, it is also possible to employ | adopt the following methods as a slag solidification process besides said method.
That is, (a) The molten slag after dephosphorization treatment is inclined to the slag pot by tilting the converter-type pot, and then the molten slag in the slag pot is put into the first heat-resistant container which can be tilted. (C) The molten slag is rapidly cooled and solidified to, for example, about 600 ° C. by water spraying in the first heat resistant container, and then the solidified slag is crushed, and (c) the first The heat resistant container is tilted, and the solidified slag is crushed by sliding into the second heat resistant container.

In any of the two types of slag solidification steps as described above, it is preferable to rapidly cool the molten slag by performing watering or the like when the molten slag is solidified. By rapidly cooling the molten slag, both 2CaO · SiO ₂ -3CaO · P ₂ O ₅ solid solution and FeO-MnO-CaO-SiO ₂ solid solution can be formed in the slag more reliably. Become.

[5. Slag grinding process]
The slag pulverizing step shown in the above (5) is a step of pulverizing the steelmaking slag solidified as described above so as to have a desired particle diameter.

In the slag crushing step, steelmaking slag in a solid state is crushed / crushed to a desired particle size by using known means such as, for example, a jaw crusher, a hammer crusher, a rod mill, a ball mill, a roll mill and a roller mill. Here, as mentioned earlier, the particle diameter of steelmaking slag is such that the total particle diameter is less than 5 mm, and the mass ratio of the particle diameter less than 600 μm is 60% or more with respect to the total mass. Preferably, crushing / crushing.

Through the steps as described above, the steelmaking slag for a fertilizer raw material according to the present embodiment is manufactured.

<About the manufacturing method of fertilizer>
Then, the manufacturing method of the fertilizer using steelmaking slag for fertilizer materials which concerns on this embodiment is demonstrated easily.
The steelmaking slag for a fertilizer material according to the present embodiment as described above can be used as a fertilizer as it is by adjusting the particle size thereof within a predetermined range (for example, all less than about 600 μm). That is, the method for producing fertilizer according to the present embodiment is to pulverize the steelmaking slag for fertilizer raw material manufactured by the above method for manufacturing steelmaking slag for fertilizer raw material by a known means.

Moreover, although the steelmaking slag for fertilizer raw materials after pulverization can be used as a fertilizer as it is as mentioned above, you may granulate, after adding a predetermined | prescribed binder. Here, the binder used in granulation is not particularly limited, and, for example, molasses, lignin, metal salts of lignin sulfonic acid, starch, polyvinyl alcohol, carboxymethyl cellulose and the like can be used.

Furthermore, an organic matter may be further mixed with the fertilizer obtained by the method as described above. As such an organic substance, for example, at least one of livestock manure such as cow dung, pig dung and chicken dung, plant residue, and compost obtained from fish and shellfish can be mentioned. By further mixing such an organic substance, it becomes possible to further improve the fertilizer effect of the fertilizer containing the steelmaking slag for a fertilizer material according to the present embodiment.

Phosphorus (P), iron (Fe), manganese (Mn), silicon (Si), calcium (Ca), magnesium (Mg), boron (B), sulfur, and the like according to the fertilizer according to the present embodiment as described above It becomes possible to more effectively supply each type of various elements of (S).

<About fertilization method>
Then, the fertilization method of the fertilizer containing the steelmaking slag for fertilizer materials which concerns on this embodiment is demonstrated.
As described above, fertilizers containing steelmaking slag for fertilizer raw materials can be used easily and at low cost without causing runoff due to water flow, even if it is acidic soil in areas with high rainfall or areas with high amounts of river flooding. Elements can be supplied as plant fertilizers. More specifically, by fertilizing a specific acidic soil in a manner as described below, alkalinization of the acidic soil can be achieved, and various types of plants can be more effectively applied to the plants desired to grow. Elements can be supplied as fertilizer.

That is, in the fertilization method according to the present embodiment, the fertilizer containing steelmaking slag for fertilizer raw material as described above or the fertilizer containing (i) pH (H ₂ O) is 4 or more and 6 or less, (ii) (pH Fertilization is applied to the soil in which the value represented by H ₂ O) -pH (KCl)) is 1 or more and (iii) effective state phosphoric acid is 5 mg / 100 g or less dry soil.

Here, pH (H ₂ O) means the pH of the suspension obtained by adding water to the soil at a predetermined ratio, and pH (KCl) means a predetermined ratio to the soil Means the pH of the suspension obtained by addition of potassium chloride solution. There are two types of hydrogen ions H ⁺ present in the soil: those dissolved in soil moisture and those that are electrically adsorbed on the surface of soil colloid particles (eg, clay, humus etc.) Do. pH _(H 2 O) represents the concentration of ^{H +} dissolved in the soil moisture, pH (KCl) has a ^{H +} dissolved in the soil moisture, and ^{H +} adsorbed on the soil colloidal particles Represents the total concentration of. While pH (H ₂ O) shows the strength of the soil acidity (active acidity) directly related to the growth of plant roots, pH (KCl) shows the potential acidity (latent acidity) of the soil It is said.

The value shown in the above (ii) can be used as an index of how much Al is present in the soil. In addition, the effective phosphoric acid shown in (iii) indicates the amount of phosphoric acid that can be absorbed by plants, and is measured by a known test method such as a fertilizer using a sulfuric acid solution having a pH of about 3 such as a truog method. be able to. Soil status of effective phosphoric acid: 5 mg / 100 g or less Dry soil indicates that the soil has a very low supply of phosphoric acid. For example, in Japan, the recommended value of effective phosphoric acid of farmland soil by the Ministry of Agriculture, Forestry and Fisheries is 10 to 75 mg / 100 g dry soil. In an acidic soil with a large value of pH (H ₂ O) -pH (KCl) and a large amount of Al, phosphate ions combine with Al ions to insolubilize as AlPO ₄ and phosphates that plants can absorb can be absorbed. There is a concern that The fertilizer which concerns on this embodiment can supply phosphoric acid with respect to the soil which lacks such an effective form phosphoric acid, and exhibits a fertilizer effect.

The above pH (H ₂ O) and pH (KCl) are as follows: 20 g of air-dried earth is put in a 100 ml shaking jar, 50 ml of distilled water or 50 ml of 1 N KCl aqueous solution is added and shaken for 30 minutes, and then the pH of the aqueous solution is adjusted to pH It can measure by measuring with a glass electrode. Further, the effective phosphoric acid content can be measured by the truog method.

The fertilizer which concerns on this embodiment exhibits the outstanding fertilizer effect with respect to the above specific acidic soils in the area which each fertilizer effect element tends to run out and runs short by heavy rain.

Here, it is preferable that the application amount of the fertilizer which concerns on this embodiment is 0.05 t / ha or more and 2 t / ha or less as steelmaking slag for fertilizer raw materials. When the application rate is less than 0.05 t / ha, the application rate is too low, and there is a possibility that the effects of the fertilizer according to the present embodiment containing a plurality of fertilizer effect elements can not be exhibited clearly. On the other hand, when the application rate exceeds 2 t / ha, the cost is increased by using a large amount of the fertilizer according to the present embodiment. A more preferable application rate is 0.1 t / ha or more and 1 t / ha or less.

In the fertilization method according to the present embodiment, the fertilizer according to the present embodiment as described above may be spread on the surface of the soil layer or mixed with the soil layer before sowing or planting seedlings. In addition, the fertilizer according to the present embodiment as described above may be spread on the surface of the soil layer in the vicinity of the plant to be grown, or may be mixed in the soil layer.

The target crops of the fertilizer according to the present embodiment as described above include, for example, gramineous plants, cypress plants, cucurbitaceous plants, leguminous plants, rhizophorbiaceous plants, liliaceous plants, solanaceous plants, cruciferous plants, Rosaceae plants, plants of the family Acaridaceae, plants of the family of the family Acaceae, plants of the family Vines, plants of the family Araceae, plants of the family Araceae, plants of the family Araceae, plants of the family Asteraceae, plants of the family Goma A plant, a pepper plant, a plant of the family Racaceae, a plant belonging to any of the family Nemetaceae, and the like can be mentioned. The steelmaking slag for fertilizer raw materials according to the present embodiment is apt to release three elements, secondary elements and trace elements of fertilizer, and the fertilizer using such steelmaking slag for fertilizer raw materials is as shown in the following examples. Since the effect is demonstrated in rice, which is a representative gramineous plant, it is expected that the effect can be obtained also for the above-mentioned plants other than the gramineous family. Moreover, it is needless to say that the fertilizer which concerns on this embodiment is applicable also to plants other than the above.

Heretofore, the fertilization method according to the present embodiment has been briefly described.

Below, the steelmaking slag for fertilizer raw materials which concerns on this invention, and the fertilizer and fertilization method using this steelmaking slag which concern on this invention are concretely demonstrated, showing an Example and a comparative example. The examples shown below are merely examples, and the present invention is not limited to the examples shown below.

Example 1
Steelmaking slag for fertilizer materials was manufactured by the method shown below.
That is, after additionally charging a manganese-containing decarburized slag to a general blast furnace hot metal in a converter having a void ratio represented by (free board / height in furnace) of 0.7, quick lime having an average particle diameter of 1 mm or less And oxygen were blown from a lance inserted into a hot metal and dephosphorization treatment was performed while forming at 1350 ° C. After steel removal, two cooling processes were performed on the produced slag. One was to tilt the converter, put it in a plate-shaped heat-resistant container, spread thinly, and then sprinkle water to quench it. The other was to tilt the converter and put it in a slag pot, and after 30 minutes, remove the slag by tilting the slag pot at an exhausting site, leave it for a while, and slowly cooled it to normal temperature.

The quenched steelmaking slag and the slowly cooled steelmaking slag obtained as described above were respectively crushed so that the total particle diameter was less than 5 mm, and the mass ratio of particles having a particle diameter of less than 600 μm was 60% or more. Analysis of the obtained steelmaking slag was performed according to the method described above, and the analysis results of the quenched steelmaking slag are shown in Table 1 below. The fluorescent X-ray analyzer used for the analysis is ZSX Primus II manufactured by Rigaku Denki Co., Ltd., and the ICP emission spectral analyzer used for the analysis is ICPS-8100 manufactured by Shimadzu Corporation.

The chemical compositions of the rapidly quenched steelmaking slag and the gradually cooled steelmaking slag were identical to each other. Moreover, the mass ratio of soluble P ₂ O ₅ , the mass ratio of hexasoluble MnO, and the mass ratio of hexasoluble boron of the gradually cooled steelmaking slag were 60%, 65%, and 75%, respectively.

Here, in Table 1 below, units of items other than basicity and specific gravity are% by mass, and values of soluble P ₂ O ₅ , water-soluble MnO and water-soluble boron are contents converted. Also, in Table 1 below, the alkali content refers to the ability of the fertilizer to neutralize the acidity of the soil, and is used by the National Institute of Agriculture and Forestry Consumption Safety Technology Center (Food and Agricultural Materials Inspection Center: It shows the value measured by the ethylenediaminetetraacetate method described in the test method for fertilizers etc. (2016) specified by FAMIC).

From Table 1 below, the quenched steelmaking slag has a weight percentage of soluble P ₂ O ₅ of 80%, a weight percentage of water-soluble MnO is 83%, and a weight ratio of water-soluble boron is 100%. In addition, the total content of CaO, P ₂ O ₅ , SiO ₂ , MgO, Al ₂ O ₃ , total iron, MnO, boron, and sulfur of the obtained steelmaking slag is 97.761 mass%, The remainder was an impurity.

In addition, X-ray diffraction (X-ray diffractometer SmartLab made by RIGAKU) and EPMA (JXA made by JEOL Ltd.) according to the method described above in accordance with the method described earlier, the materials constituting the crystal phase of each of the rapidly solidified steel slag The results obtained are shown in Table 2 below. In Table 2 shown below, "(circle)" has shown that the solid solution to which its attention was paid was confirmed, and "x" has shown that the solid solution which it focused on was not confirmed. As apparent from Table 2 below, in the quenched steelmaking slag, the presence of both 2CaO · SiO ₂ -3CaO · P ₂ O ₅ solid solution and FeO-MnO-CaO-SiO ₂ solid solution was confirmed. In the slowly cooled steelmaking slag, the presence of 2CaO · SiO ₂ -3CaO · P ₂ O ₅ solid solution could be confirmed, but the presence of FeO-MnO-CaO-SiO ₂ solid solution could not be confirmed.

 

 

(Example 2)
A cultivation test of rice was carried out in the soil whose analysis results are described in Table 3 below using the above-mentioned fertilizer. In this soil, pH (H ₂ O), pH (KCl), and effective phosphoric acid content were measured by the method described above, and the pH (H ₂ O) was in the range of 4 or more and 6 or less. The value of pH (H ₂ O) -pH (KCl) was 1 or more, and the effective phosphoric acid content was also 5 mg / 100 g or less dry soil.

 

 

More specifically, in the case of applying a fertilizer that uses the above-described quenched steelmaking slag and slowly cooled steelmaking slag as a raw material, and a void ratio represented by (free board / in-furnace height) is 0.4 in the converter The fertilizer effect test for rice was conducted in the case of applying a commercial fertilizer that uses the steelmaking slag generated in the above as a raw material and in the case where the fertilizer that uses a steelmaking slag as a raw material is not applied.

The analysis result of the commercially available fertilizer which uses as a raw material steelmaking slag which generate | occur | produced in the converter of which the void ratio represented by (free board / furnace height) is 0.4 is shown in the following Table 4. The analysis method of the commercially available fertilizer was performed in the same manner as in Example 1. In Table 4 below, units of items other than basicity and specific gravity are% by mass, and values of soluble P ₂ O ₅ , water-soluble MnO and water-soluble boron are contents converted. The alkali content was measured in the same manner as in Table 1 above.

From Table 4 below, in the steelmaking slag generated in the converter with a void ratio of 0.4, the mass fraction of soluble P ₂ O ₅ is 44%, and the mass fraction of non-soluble MnO is 53%, The mass fraction of soluble boron is 80%. In addition, the total content of CaO, P ₂ O ₅ , SiO ₂ , MgO, Al ₂ O ₃ , total iron, MnO, boron, and sulfur for steelmaking slag generated in a converter having a void ratio of 0.4 Was 84.105% by mass, and the balance was impurities.

In addition, it was confirmed that the commercially available fertilizer had an overall particle size of less than 5 mm, and that the mass ratio of particles having a particle size of less than 600 μm was 60% or more.

The fertilizer which uses steelmaking slag whose analysis results are shown in Table 4 as a raw material has a high basicity because the content ratio of SiO _{2 to} CaO is small compared to the fertilizer which uses steelmaking slag according to the present invention as a raw material. The content of ₂ O ₅ and soluble P ₂ O ₅ is low. Moreover, compared with the fertilizer which uses two types of slag which showed the composition in the said Table 1 as a raw material, although content of total iron is large, content of incompatible | soluble MnO is somewhat low.

The materials constituting the crystal phase of steelmaking slag, which is a raw material of the above-mentioned commercial fertilizer, were examined by X-ray diffraction and EPMA according to the method described above, and the obtained results are shown in Table 5 below. . The notation in Table 5 below is the same as in Table 2. As shown in Table 5 below, neither the presence of the 2CaO · SiO ₂ -3CaO · P ₂ O ₅ solid solution nor the presence of the FeO-MnO-CaO-SiO ₂ -based solid solution could be confirmed.

 

 

Nitrogen and potassium as basic fertilizer and 60 kg / ha each as urea and potassium chloride were added to the soil of the paddy field before rice planting. In this paddy field, 9 frames of 0.6 x 0.5 m were installed, and the fertilizer and sludge from which the quenched steelmaking slag is used as the raw material whose analysis results are shown in Table 1 and 2 are shown in 3 of them. Fertilizers that use cold steelmaking slag as a raw material, and commercially available fertilizers that use steelmaking slag made in a converter with a void ratio of 0.4 whose analysis results are shown in Table 4 and Table 5 (each of which 15 g of each was added (corresponding to an application rate of 0.5 t / ha), in which the particle size was less than 5 mm, and the mass ratio of particles less than 600 μm was confirmed to be 60% or more.

After thoroughly mixing with the soil of 10 cm in depth, four seedlings of rice (variety: Koshihikari) were planted as six ones in each frame and cultivated until the harvest period. In addition, as a control, tests were conducted under the same conditions for three frames to which no material was added. Therefore, the test was performed in triplicate.

The yield survey was conducted 4 months after planting the rice. All six stocks in each frame were harvested and refined rice weight and thousand grain weight were examined. The obtained results are shown in Table 6 below.

 

 

As apparent from Table 6 above, the application of fertilizers using the quenched steelmaking slag as a raw material increased the yield (fresh rice weight) by about 31% as compared with the control. In addition, when slowly cooling steelmaking slag was applied, the yield (fine rice weight) increased by about 26% as compared with the control. On the other hand, when the same amount of commercial fertilizer made from existing steelmaking slag was applied, the yield (fresh rice weight) increased by about 10% compared to the control.

In addition, with regard to the one thousand-grain weight, the highest value is obtained when applying the fertilizer using the quenched steelmaking slag as the raw material, and the second highest value is obtained when applying the fertilizer using the gradually cooled steelmaking slag as the raw material. The case where the raw material fertilizer was applied became the third highest value, and the case where the raw material fertilizer was not applied became the lowest value.

From this result, even if it is steelmaking slag for fertilizer raw materials of the same chemical composition, quenched steelmaking containing both 2CaO · SiO ₂ -3CaO · P ₂ O ₅ solid solution and FeO-MnO-CaO-SiO ₂ solid solution It is clear that the slag has higher fertilizer effect than the slowly cooled steelmaking slag containing 2CaO · SiO ₂ -3CaO · P ₂ O ₅ solid solution but not FeO-MnO-CaO-SiO ₂ solid solution. became.

As explained above, it became clear that it is possible to increase the yield of rice by using the fertilizer which uses steelmaking slag for fertilizer materials concerning the present invention as a raw material.

(Example 3)
Analysis results shown in Table 7 below using the fertilizer using the quenched steelmaking slag as a raw material, the fertilizer using slowly cooled steelmaking slag, and the commercially available fertilizer using a steelmaking slag as described in Example 2 above The cultivation test of paddy rice was carried out in the soil where The soil analysis method is the same as in Example 2.

 

 

Nitrogen and potassium as basic fertilizer and 60 kg / ha each as urea and potassium chloride were added to the soil of the paddy field before rice planting. In this paddy field, 9 frames of 0.6 x 0.5 m were installed, and the fertilizer and sludge from which the quenched steelmaking slag is used as the raw material whose analysis results are shown in Table 1 and 2 are shown in 3 of them. Fertilizers that use chilled steelmaking slag as a raw material, and commercially available fertilizers that use steelmaking slag as a raw material whose analysis results are shown in Table 4 and Table 5 (each with a total particle size of less than 5 mm, and a particle size 15 g each were added (corresponding to an application rate of 0.5 t / ha).

After thoroughly mixing with the soil of 10 cm in depth, four seedlings of rice (variety: Koshihikari) were planted as six ones in each frame and cultivated until the harvest period. In addition, as a control, tests were conducted under the same conditions for three frames to which no material was added. Therefore, the test was performed in triplicate.

The yield survey was conducted 4 months after planting the rice. All six stocks in each frame were harvested and refined rice weight and thousand grain weight were examined. The obtained results are shown in Table 8 below.

 

 

As is apparent from Table 8 above, the application of fertilizers using the quenched steelmaking slag as a raw material increased the yield (fresh rice weight) by about 12% as compared with the control. In addition, when slowly cooling steelmaking slag was applied, the yield (fine rice weight) increased by about 8% as compared with the control. On the other hand, when the same amount of commercial fertilizers made from existing steelmaking slag was applied, the yield (fine rice weight) increased by about 3% compared to the control.

In addition, with regard to the one thousand-grain weight, the highest value is obtained when applying the fertilizer using the quenched steelmaking slag as the raw material, and the second highest value is obtained when applying the fertilizer using the gradually cooled steelmaking slag as the raw material. The case where the raw material fertilizer was applied became the third highest value, and the case where the raw material fertilizer was not applied became the lowest value.

As explained above, it is possible to increase the yield of rice even with soil of pH (H ₂ O) 6.5 by using the fertilizer which uses the steelmaking slag for fertilizer material according to the present invention as the raw material It became clear that.

However, in comparison with the results of Example 2, in the soil where the analysis results are shown in Table 3, the yield when applying the fertilizer using the steelmaking slag for fertilizer material according to the present invention is the control without applying the steelmaking slag fertilizer. In the soil where the analysis results are shown in Table 7, the yield when applying the fertilizer using the steelmaking slag for a fertilizer material according to the present invention is about 30% higher than the yield of the ward. The increase was reduced by about 12% compared to the yield of the control without application of steelmaking slag fertilizer. The reason for this is that the yield of the control section where no steelmaking slag fertilizer is applied is higher than that of Example 2. The pH (H ₂ O) of the soil, the analytical results of which are shown in Table 7, is in the range of pH 5.5 to 6.5 suitable for the growth of rice, and the effective phosphate is also 15 mg / 100 g dry soil. Since it is within the recommended value (10 to 75 mg / 100 g dry soil) of effective phosphoric acid of farmland soil by the Ministry of Agriculture, Forestry and Fisheries, phosphoric acid can be supplied from the soil without using fertilizer made from steelmaking slag as a raw material Can be considered as the reason.

Therefore, it was revealed that the fertilizer using the steelmaking slag for fertilizer material according to the present invention as the raw material has the more remarkable effect in the soil of Table 3 although it is effective even in the soil of Table 7.

Although the preferred embodiments of the present invention have been described above in detail, the present invention is not limited to such examples. It is obvious that those skilled in the art to which the present invention belongs can conceive of various changes or modifications within the scope of the technical idea described in the claims. Of course, it is understood that these also fall within the technical scope of the present invention.

Claims (18)

In mass%,
P ₂ O ₅ : 2% or more and 8% or less,
MnO: 3% or more and 10% or less,
Boron: 0.005% or more and less than 0.05%,
Total iron: 7% or more and less than 15%,
CaO: 38% or more and 48% or less,
SiO ₂ : 22% or more and 30% or less,
Sulfur: 0.1% to 0.6%,
MgO: 1% to 8%,
Al ₂ O ₃ : 0.5% or more and 3% or less,
Contains
The proportion of soluble _P 2 _{O 5} in the _P 2 _{O 5} is, is 50% or more,
The proportion of soluble MnO in the above MnO is 80% or more,
The slag basicity represented by (CaO content / SiO ₂ content) is more than 1.5 and not more than 2.2,
Steelmaking slag for fertilizer raw material whose bulk specific gravity is 1.9 or more and 2.8 or less. _{2CaO · SiO 2 -3CaO · P 2} O 5 solid solution, and contains FeO-MnO-CaO-SiO ₂ solid solution, respectively, fertilizer feedstock steel slag according to claim 1. The steelmaking slag for fertilizer raw materials of Claim 1 or 2 whose ratio of the soluble boron in the said boron is 95% or more. The fertilizer according to any one of claims 1 to 3, wherein a mass ratio of particles having a particle size of less than 5 mm as a whole and having a particle size of less than 600 μm is 60% or more with respect to the total mass. Steelmaking slag for raw materials. It is a manufacturing method of steelmaking slag for fertilizer materials according to any one of claims 1 to 4,
For the converter-type pan, the void ratio represented by (the freeboard corresponding to the length from the furnace opening to the melt surface / the height in the furnace corresponding to the length from the furnace opening to the bottom of the furnace) is 0. Inject blast furnace hot metal so as to be 5 or more and 0.9 or less,
Manganese ore, manganese-containing decarburized slag, and / or ferromanganese are added to the blast furnace hot metal in the converter-type pan,
From the lance inserted in the blast furnace hot metal, quick lime and / or calcium carbonate having an average particle size of 1 mm or less and oxygen are blown into the blast furnace hot metal,
Dephosphorization treatment is performed by forming slag at 1300 ° C or more and 1400 ° C or less,
Slag basicity represented by (CaO content / SiO ₂ content) is more than 1.5 and 2.2 or less, and MnO content in the slag is 3 mass% or more and 10 mass% or less The manufacturing method of steelmaking slag for fertilizer raw materials to manufacture. The manufacturing method of steelmaking slag for fertilizer raw materials of Claim 5 which inject | pours the molten slag after the said dephosphorization process in a dish-shaped heat resistant container, and it solidifies by rapid-cooling. The method for producing steelmaking slag for fertilizer material according to claim 6, wherein the molten slag after the dephosphorization treatment is rapidly cooled by performing watering. After the molten slag after the dephosphorization treatment is inclined to the slag pot by tilting the converter-type pan, the molten slag in the slag pot is inclined to the first heat-resistant container which can be tilted. ,
The molten slag is rapidly cooled and solidified by watering in the first heat resistant container, and then the solidified slag is crushed;
The steel material for fertilizer material according to any one of claims 5 to 7, wherein the first heat-resistant container is tilted and crushed to be crushed by sliding the solidified slag into a second heat-resistant container. Production method of slag. The fertilizer raw material according to any one of claims 5 to 8, wherein 2CaO · SiO ₂ -3CaO · P ₂ O ₅ solid solution and FeO-MnO-CaO-SiO ₂ solid solution are respectively formed by rapid cooling. Production method of steelmaking slag. 10. The slag is pulverized so that the mass ratio of particles having a particle diameter of less than 5 mm as a whole and having a particle diameter of less than 600 μm is 60% or more with respect to the total mass. The manufacturing method of steelmaking slag for fertilizer raw materials of 1st term. A steelmaking slag for a fertilizer raw material according to any one of claims 1 to 4, or a fertilizer raw material manufactured by the method for producing a steelmaking slag for a fertilizer raw material according to any one of claims 5 to 10. Method of producing fertilizer for pulverizing steelmaking slag for use. The manufacturing method of the fertilizer according to claim 11 which granulates, after adding a predetermined binder to the steelmaking slag for fertilizer materials after pulverization. The manufacturing method of the fertilizer of Claim 11 or 12 which further mixes organic substance with the obtained fertilizer. The method for producing fertilizer according to claim 13, wherein the organic matter is at least one of livestock manure, plant residue, and compost obtained from fish and shellfish. The steelmaking slag for fertilizer raw materials according to any one of claims 1 to 4, the steelmaking slag for fertilizer raw materials manufactured by the method for manufacturing steelmaking slag for fertilizer raw materials according to any one of claims 5 to 10, Alternatively, a fertilizer comprising a fertilizer produced by the method for producing a fertilizer according to any one of claims 11 to 14,
The pH (H ₂ O) is 4 or more and 6 or less, the value represented by (pH (H ₂ O) -pH (KCl)) is 1 or more, and the effective phosphoric acid is 5 mg / 100 g dry earth Fertilization method to fertilize the soil which is the following. The fertilization method according to claim 15, wherein the application amount of the fertilizer is 0.05 t / ha or more and 2 t / ha or less as the steelmaking slag for the fertilizer raw material. The fertilization method according to claim 15 or 16, wherein the fertilizer is spread on the soil layer surface or mixed with the soil layer before sowing or planting. The fertilization method of Claim 15 or 16 which spreads the said fertilizer on the soil layer surface of the vicinity of the plant body to grow, or mixes it in the said soil layer.