JP2636612B2 - Production method of ultra-fast hardening cement raw material modified from steel slag - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for effectively utilizing CaF ₂ -containing steel slag generated in a hot metal pretreatment or a steelmaking process using fluorite, and more specifically, a method for modifying this steel slag to ultra-fast hardening. The present invention relates to a method for producing a cement raw material (clinker).

[0002]

2. Description of the Related Art In a hot metal pretreatment or steelmaking process,
Fluorite as a part of auxiliary materials such as solvent (flux)
Processing using (CaF ₂ ) may be performed. For example, the dephosphorization of hot metal is preferably performed at a low temperature in terms of dephosphorization efficiency and cost, and fluorite is often used as a low-melting-point solvent for the purpose of promoting slag slagging at the low-temperature treatment.

[0003] The steel slag (slag) generated by the treatment using fluorite contains a considerable amount of unreacted CaF _2, which may cause elution of fluorine ions. There was no other method of use. Take it there
Focusing on the fact that the composition is relatively similar to the cement raw material in order to achieve high value-added use of CaF ₂ -containing steel slag, this steel slag was modified to improve the cement raw material, especially the ultra-rapid hardening cement raw material. Attempts have been made to use it.

[0004] For example, Japanese Patent Publication No. Sho 57-34223, in weight%, CaO = 68~72%, Fe 2 0 3 = 0.2 ~1.0%, SiO 2 =
_{22~26%, P 2 0 5 =} 0.1 ~0.6%, Al 2 0 3 = 1~3%,
TiO ₂ = 0.4-0.9%, MnO = 0.4% or less, CaF ₂
= 0.3-2.0%, MgO = 0.3-3.0%. The mineral structure is mainly 3CaO.Si
A method for producing a steel slag cement modified from a steel slag, characterized in that it is present in the form of O ₂ and is substantially free of 3CaO.Al ₂ O _3, is disclosed.

[0005] This, Al ₂ 0 ₃ is small in the steel slags cement component, mineral tissue ultrafast _{11CaO · 7Al 2 0 3 · CaF} 2 showing the hard is hardly present, those similar to the so-called early strength cement It is. Japanese Patent Application Laid-Open No. 63-206336 discloses a method for producing a rapid-hardening cement using dephosphorized slag, in which an alumina source and a lime source are mixed with a dephosphorized slag powder from which magnetic iron has been removed by magnetic separation, and 850 to 1250. and fired at _{℃, 11CaO · 7Al 2 0 3} ·
A method is disclosed in which a clinker containing CaF ₂ as a main component is produced, pulverized, and then added with gypsum to obtain a quick-setting cement.

[0006] However, the cement produced by this method has a low ultra-rapid hardening property, and the compressive strength after 1 hour in the JIS mortar test is ² to 6 kgf / cm2. This compressive strength is equivalent to 35
~40kg weigh / cm ² problem that much lower and 1/6 or less compared to. In addition, since the dephosphorized slag after the magnetic separation is used as a raw material, the sensible heat of the hot steel slag cannot be used effectively, and the production cost is high.In addition, MnO cannot be removed. There is also the problem of being brown.

Japanese Patent Application Laid-Open No. Hei 2-236214 discloses that lime, limestone, iron oxide, fluorite, aluminum, aluminum dross, and alumina are added to molten steel during refining or hot metal in a hot metal pretreatment process by top charge or injection. By mixing one or more of waste, bauxite, and aluminum hydroxide, the steel slag component is CaO = 35-45% by weight,
And Al ₂ 0 ₃ = 25~35%, the main component of the solidified steel slag component 1
Characterized in that the 2CaO · 7Al ₂ 0 ₃ or _{11CaO · 7Al 2 0 3 · CaF} 2 and so as method for modifying the steel slags are described.

[0008] The modified steel slag obtained by this method is used as an ultra-rapid hardening cement raw material as a quick setting agent. Since this reforming method is performed during refining, the steel slag cannot be reduced before the steel slag reforming process. Therefore, the resulting modified steel slags are FeO, rich in iron, such as Fe ₂ 0 _3, and because rich in MnO, requires that to magnetic separation process in a subsequent step to remove the iron, the operation rather complicated Becomes Further, it is impossible to remove MnO from steel slag, and as described above, the presence of MnO causes a problem that the cement strength is hindered and the color of the cement becomes brownish.

[0009]

Cree INVENTION SUMMARY is] is earlier, Japanese Patent Application No. Hei 2-413805, reduced as Nos. 3-79117, the CaF ₂ content thermal steel slags generated in the hot metal pretreatment or steelmaking process after agent were melted reduced at 1,300-1,800 ° C. in addition, by gravity separation ferroalloys of sediment, FeO + Fe ₂ 0 ₃ content of 0.1 to 5 wt%, MnO + Mn ₂ 0 ₃ content of 2.0 wt% to less The components were adjusted, and then an alumina source and a lime source were added to the hot steel slag, and the composition was adjusted to Al ₂ O ₃ with respect to 1 mole of CaF _2.
A method of firing the hot steel slag at 850 to 1250 ° C. after adjusting to 3 to 10 mol and CaO 5 to 17 mol has been disclosed.

[0010] However, as a result of subsequent studies, this method shows that in this method, an alumina source and limestone are charged into the hot steel slag after the reduction treatment, and calcined in a temperature range of 850 to 1250 ° C. It has been found that the mixing of the sources is not sufficient, and there is a problem that uneven baking occurs in the generated mineral phase during firing.

[0011] When such a baked irregularity occurs, it did not determine the variation of raw materials for cement _{(clinker) 11CaO · 7Al 2 0 3 ·} CaF 2 generation amount in the increases. Thus, an object of the present invention is to provide a method for producing a super-rapid hardened cement raw material which is obtained by modifying steel slag without the above-mentioned problems.

[0012]

Means for Solving the Problems The inventors of the present invention have studied to solve the above problems, and as a result, after the reduction treatment, the steel slag was once cooled, crushed and pulverized to form an alumina source and a limestone source. And mix well, then 850-1250 ° C
The present inventors have found that a super-rapid hardened cement raw material excellent in quality and yield can be produced by the reforming treatment of sintering, and the present invention has been completed. Here, the present invention provides the following steps (i) to
(v) The method for producing a super-rapidly hardened cement raw material by modifying a CaF ₂ -containing hot steel slag.

(I) a step of adding a reducing agent to the CaF ₂ -containing steel slag generated in the hot metal pretreatment or steelmaking process to perform smelting reduction at 1300 to 1800 ° C .; (ii) separating specific gravity of the smelting-reduced and precipitated alloy iron; And FeO
+ Fe ₂ 0 ₃ content of 0.1 to 5 wt%, MnO + Mn ₂ 0 ₃ content of 2.
(Iii) cooling and grinding the recovered hot steel slag, (iv) mixing an alumina source and a lime source with the ground steel slag. Te, Al ₂ 0 ₃ 3~10 moles its composition to CaF ₂ 1 mole, Ca
(5) adjusting the mixture to a ratio of 5 to 17 mol of O and mixing; and (v) calcining the obtained mixture at 850 to 1250 ° C.
· 7Al ₂ 0 ₃ · to obtain a product of CaF ₂ as a main component.

According to the present invention, a CaF ₂ -containing steel slag generated in a pretreatment step or a refining step is charged with a reducing agent such as aluminum ash, preferably in a state of a hot steel slag left in a converter. and injection with N ₂ and the like at blowing or Soko吹or upper base _{吹等, FeO, Fe 2 0 3,} MnO, melted reducing the Mn ₂ 0 _3, to gravity separation as an alloy of iron (Fe-Mn), then cooled and solidified, after pulverization by crushing the steel slags, alumina source and is blended lime source, were allowed to thoroughly mix, the heat source of CaF ₂ containing hot steel slags by firing treatment effect when reduction treatment It can be used, and after the reduction treatment, the steel slag is cooled and solidified, crushed and pulverized, then the alumina source and the lime source are blended, sufficiently mixed, and calcined, and the quality of the cement deteriorates. Contains no Fe and Mn components and produces no firing unevenness High quality of super-fast hard cement raw materials can be produced.

The hot steel slag to be treated in the present invention is not particularly limited as long as it is a CaF ₂ -containing hot slag generated in the hot metal pretreatment or steelmaking process. A typical example is a dephosphorized slag using fluorite as a part of a solvent, but as long as CaF ₂ is contained,
Other steel slag can also be used. The amount of CaF ₂ in the steel slag is also not particularly limited, but the CaF ₂ content is preferably 3% by weight or more in order to effectively produce the desired 11CaO · 7Al ₂ O ₃ · CaF ₂ .

As the reducing agent to be added to the hot steel slag,
Metallic aluminum, metallic aluminum-containing materials (aluminum cans, aluminum ash, etc.), carbon or carbon sources (coke breeze, coal, pitch, electrode scraps, etc.), carbon monoxide, etc. can be used. Good metallic aluminum or metallic aluminum inclusions are most preferred.

[0017] As the alumina source, anything can be used as long as the material containing Al ₂ 0 _3. Examples of suitable alumina sources are aluminum ash, aluminum dross, bauxite, aluminum hydroxide. As the lime source, any material containing CaO can be used. Preferred lime sources include quicklime, limestone, slaked lime.

For cooling and pulverizing the hot steel slag from which the ferromagnetic iron has been separated, the hot steel slag is once discharged from a metallurgical processing furnace such as a converter,
It may be cooled in the air as it is, or may be forced air-cooled air crushing. Furthermore, rapid cooling water granulation by water cooling may be used. The pulverization after cooling may be performed by a conventional pulverizing means such as a ball mill. Preferably, the specific surface area is 1000 to 20,000 cm ² /
and g range, but most preferably milled to about 3000~ 7000 cm ² / g.

[0019]

Next, the operation of each processing step in the present invention will be specifically described. (i) Smelting reduction step: According to the method of the present invention, first, a steel slag containing CaF ₂ generated in a hot metal pretreatment or steelmaking process.
(For example, some steel may be included.) For example, the CaF ₂ -containing hot steel slag generated by the dephosphorization treatment in the converter is left in the converter, and a reducing agent is immediately added in a molten state to reduce the temperature at 1300 to 1800 ° C. I do.

In a preferred embodiment, after adding the reducing agent,
Injection using inert gas (N ₂ , Ar gas, etc.) in top blowing or bottom blowing or top and bottom blowing to reduce and homogenize the reduction reaction at 1300 to 1800 ° C while homogenizing the reduction reaction.
By reduction of _{Fe 2 0 3 · MnO · Mn} 2 0 3 and alloy iron (Fe-Mn).

The type of reducing agent to be used may be selected in view of the heat of oxidation, the temperature of the steel slag before the reduction treatment and the reactivity in order to keep the temperature of the steel slag during the reduction treatment at 1300 to 1800 ° C. However, particularly suitable reducing agents include metallic aluminum or metallic aluminum containing materials. The reason for performing the reduction process is as follows.

[0022] [Fe ₂ 0 ₃ in the cement] Fe ₂ 0 ₃ has an important role to act as a medium solvent in cement production, to impart other cement unique color scheme makes it easy firing and compounds of cement material . But Fe ₂ 0 ₃
From that acts to suppress the hydration of such _{11CaO · 7Al 2 0 3 · CaF} 2 and 3CaO · SiO _2, in the ultrarapid hardening cement it is important to the oxidation iron to low. Therefore, in the ultrarapid cement, the Fe ₂ 0 ₃ content of 0.1 to
2.0% by weight.

[0023] [MnO in the cement, Mn ₂ 0 _3] MnO (Mn ₂ 0 ₃₎
In cement production, cement strength is impaired by reducing the amount of 3CaO · SiO ₂ generated during firing. There is also the color of the cement problem of browning, MnO (Mn ₂ 0 ₃₎ content in the cement is a better low. According to the Cement Association issue of the literature (Japan cement press release of the 35th cement technology tournament), reduction of the cement strength is as seen when more than 0.2% as Mn ₂ 0 _3.

[0024] For the above reasons, FeO in the steel slag, Fe ₂ 0 _3,
MnO, to remove Mn ₂ 0 _3, FeO in the produced clinker, Fe ₂ 0
_3, MnO, it is preferable to reduce the Mn ₂ 0 _3. The smelting reduction method is employed as a method for this purpose because iron and manganese can be separated by a simple method of specific gravity separation, and when using hot steel slag, the sensible heat can be used as it is. .

[0025] Since in order to increase the production amount of _{11CaO · 7Al 2 0 3 · CaF} 2 is the main product in the produced clinker was reformed, the firing temperature there is a need to 1250 ° C. or less, reduction process must be before the _{11CaO · 7Al 2 0 3 · CaF} 2 of the firing process. Further, as the reduction treatment temperature,
For the reasons described above, the temperature is above the melting temperature of steel slag, and CaO and
Since the Al ₂ 0 ₃ needs to be less than a temperature which is not reduced, the range of from 1,300 to 1800 ° C.. A preferred reduction treatment temperature is 1400 to 1700 ° C. As a container for the reduction process,
A converter is preferred from the viewpoint of minimizing the heat loss of the hot slag, but the hot slag may be transferred to a ladle or the like.

(Ii) Separation / recovery step: After the reduction treatment, the ferroalloy produced has a higher specific gravity than the steel slag and sinks to the furnace bottom, so that it can be separated from the steel slag by specific gravity separation. Composition of the steel slag recovered after the ferroalloy separation by the above reduction process, FeO + Fe ₂ 0 ₃ content and MnO + Mn ₂ 0 ₃ content in the steel slags are component adjustment, FeO + Fe ₂ 0 ₃ Content 0.1 〜
5 wt%, and MnO + Mn ₂ 0 ₃ content of 2.0 wt% or less.
If by reducing the content of iron oxide and manganese oxide in steel slag within this range, the ultra-fast cement clinker that has been modified by the method of the present invention obtained by blending the gypsum and Portland cement Fe ₂ 0 ₃ content and MnO (Mn ₂ 0 ₃₎ it is possible the content is adjusted to within the range described above, as a super-rapid setting cements with excellent quality.

(Iii) Cooling / Pulverizing Step: Prior to mixing the alumina source and the lime source, according to the present invention, the molten hot steel slag is cooled and solidified and then pulverized. After the hot steel slag is cooled and solidified, it is crushed and pulverized by sufficiently mixing the alumina source and the lime source and, during firing, uniformly reacting the alumina source and the lime source with the steel slag. _{, 11CaO · 7Al 2 0 3 ·} Ca
It is performed for homogenizing the product of F _2. Therefore, it is preferable that the alumina source and the lime source are similarly pulverized.

The crushing particle size of the steel slag, the alumina source and the lime source is set to a specific surface area in a range of 1000 to 20,000 cm ² / g.
~ 7000 cm ² / g is most preferred. Large variations in the production mineral phase after firing is less than 1000 cm ² / g, not only it is difficult mixing operation liable up winding becomes Konakemuri when mixed with exceeding 20,000 cm ² / g, crushed cost becomes enormous milling The effect of conversion is lost.

(Iv) Adjustment / mixing step: Before sintering, the steel slag, the alumina source and the lime source are sufficiently mixed. Therefore, the alumina source and the lime source are also used in powder form,
Before sintering, the slag is sufficiently mixed with the alumina source and the lime source before firing. The mixing means is not particularly limited,
It is sufficient to mix and pulverize with a ball mill for both pulverization and mixing.

The components in the steel slag after mixing are Al ₂ 0 ₃ 3 to 10 mol, preferably 5 to 8 mol, and CaO 5 to 1 mol of CaF _2.
17 mol, preferably 7 to 13 mol. 11CaO ・ 7Al ₂ 0 ₃
- the amount of CaF ₂ and to the maximum, Al ₂ 0 ₃ to about 7 moles, CaO about 11 moles being most preferred.

(V) Firing step: As the firing furnace, a rotary kiln is most preferable in order to make the fired product uniform, but any furnace capable of uniformly heating and firing can be used. The firing temperature is 850 to 1250 ° C. Outside this range lowers the production efficiency of _{11CaO · 7Al 2 0 3 · CaF} 2. The preferred firing temperature is 900-1200 ° C. This baked product mainly composed of _{11CaO · 7Al 2 0 3 · CaF} 2 that has been modified is recovered from the furnace gives ultrafast cement raw material (clinker).

Gypsum or Portland cement is blended with this clinker and used as an ultra-rapid hardening cement. The amount of gypsum or Portland cement is adjusted in consideration of quick-setting properties and cement strength, but usually 20 to 40% of clinker obtained by the method of the present invention, 10 to 25% of gypsum, 35 to 70 of Portland cement are obtained by weight%. %. Next, the present invention will be further described with reference to examples. In Examples, "%" is "% by weight" unless otherwise specified.

[0033]

[Example] After the dephosphorization treatment was completed in the converter, the hot steel slag was left in the converter, and aluminum ash was used as a reducing agent from the upper part to the steel slag amount to 20%.
%, And a reduction treatment was carried out for 15 minutes while injecting N ₂ gas by using a lance of the converter and blowing in N ₂ gas. The temperature of the hot steel slag at this time was 1600 to 1650 ° C. After the reduction treatment, the hot steel slag was discharged from the converter and solidified by cooling. The ferroalloy settled at the furnace bottom was separated and discharged after discharging the hot steel slag.

Next, the cooled and solidified steel slag, aluminum ash as an alumina source, and quick lime as a lime source were mixed and ground to a specific surface area of 5000 cm ² / g by a ball mill. Thereafter, firing was performed in a rotary kiln. Dephosphorized slag used, reducing agent
(Aluminum ash), alumina source (aluminum ash) and lime source
Table 1 summarizes the composition of (quick lime).

The firing conditions and results are shown in Table 2, it can be seen the variation of _{11CaO · 7Al 2 0 3 · CaF} 2 generation amount according to the method of the present invention is small. On the other hand, according to the method of JP Gantaira 2-413805 as a comparative example, as shown in the same table, that variation in the _{11CaO · 7Al 2 0 3 · CaF} 2 production amount is large was found.

(Mortar Compressive Strength Test) Powder obtained by pulverizing the clinker fired in this example to a specific surface area of 5300 cm ² / g by a ball mill was combined under the conditions shown in Table 3. In the table, ultra fast curing material is a powder of 5300cm ² / g obtained in the present example, gypsum (CaSO ₄ · 2H ₂ O) is commercially available, Portland cement was a commercial ordinary Portland cement.

[0037] FeO + Fe ₂ 0 ₃ of the cement composition after compounding
And to investigate the content of MnO + Mn ₂ 0 _3. Table 3 shows the results. Next, a mortar specimen specified in JIS R5201 was prepared and its compressive strength was examined. The results are shown in the same table.
In addition, the compressive strength of the comparative example and the jet cement which is a commercially available ultra-fast-setting cement is also described in the comparative examples in the table. In the comparative example, the variation in the compressive strength is large,
In the examples of the present invention, the dispersion was small, and the performance was equivalent to that of a commercially available jet cement.

[0038]

[Table 1]

[0039]

[Table 2]

[0040]

[Table 3]

[0041]

According to the present invention, a molten steel slag containing CaF ₂ which has been conventionally discarded for landfills can be used effectively by utilizing its sensible heat and simultaneously using a reduction treatment. The Fe and Mn components in the slag can be removed and recovered as ferrous alloys (Fe-Mn), and the calcined clinker has extremely stable ultra-rapid hardening performance. Since the recovered ferromagnetic iron can be effectively used as an auxiliary material for steelmaking or the like, the entire amount of steel slag can be effectively used. Accordingly, the present onset Ming method is not only effective use of resources, conventionally being able to supply the ultra-fast cement was relatively expensive and more cheaply, as it exhibits an extremely excellent effect on industrial is there.

Claims (1)

(57) [Claims] (1) a step of adding a reducing agent to CaF ₂ -containing steel slag generated in a hot metal pretreatment or a steelmaking process and reducing the molten iron at 1300 to 1800 ° C .; (ii) a specific gravity of the molten reduced and precipitated iron alloy Separated, FeO +
Fe ₂ 0 ₃ content of 0.1 to 5 wt%, MnO + Mn ₂ 0 ₃ content of 2.0
(Iii) cooling and grinding the recovered hot steel slag, (iv) blending the crushed steel slag with an alumina source and a lime source. , The composition of which is _{3 to} 10 mol of Al ₂ O ₃ per 1 mol of CaF ₂ ,
(5) adjusting the mixture to a ratio of 5 to 17 mol of O and mixing; and (v) calcining the obtained mixture at 850 to 1250 ° C.
· 7Al ₂ 0 ₃ · a CaF _2, characterized in that comprising the step of obtaining a product consisting mainly method of ultra-rapid-cement material which was modified steel slags.