JPH04224147A - Manufacture of raw material for ultra high-speed-hardening cement reforming slag - Google Patents

Abstract

PURPOSE:To obtain a raw material for ultra high-speed hardening cement by melting and reducing a thermal slag incorporating CaF2 with the addition of reducing agent and sintering it by adjusting the composition after separating settled ferro-alloy. CONSTITUTION:The CaF2 incorporated thermal slag (e.g. dephosphorized slag) produced in the preliminary treatment of molten steel or steel refining stage is transferred into an electric furnace as shown in a figure and after melting and reducing it at 1300-1800 deg.C with the addition of reducing agent (e.g. powdery coke), settled ferro-alloy (Fe-Mn) is separated by gravity and removed from take-out port and adjusted to 0.1-5wt.% FeO+Fe2O3 content, 2.0wt.% MnO+Mn2 O3 content. Then, by adding alumina source (e.g. alumina ash) and lime source (e.g. quick lime) into the thermal slag from a hopper and after adjusting composition to 3-10mol Al2O3 and 0.5-17mol CaO per 1mol of CaF2, sintering is carried out at 850-1250 deg.C to obtain the raw material of ultra high-speed hardening cement (clinker) consisting essentially of 11 CaO, 7 Al2O3, CaF2.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a method for effectively utilizing CaF2-containing steel slag generated during pretreatment of hot metal using fluorite or steel manufacturing process, and specifically, a method for effectively utilizing steel slag containing CaF2 generated during hot metal pretreatment using fluorite or in the steel manufacturing process. This invention relates to a method for producing raw materials (clinker).

0002

[Prior Art] In hot metal pretreatment or steel making process,
Fluorite (
Treatment using CaF2) may be performed. For example, in the dephosphorization treatment of hot metal, low-temperature treatment is preferable in terms of dephosphorization efficiency and cost, and fluorite is often used as a low-melting point solvent in order to promote formation of slag slag during low-temperature treatment. The steel slag (slag) generated in the treatment using fluorite contains a considerable amount of unreacted CaF2, and there is a concern that fluorine ions will be leached from this, so it cannot be used for purposes other than landfilling. There was no way. Therefore, such CaF
In order to utilize steel slag containing 2 with high added value, we focused on the fact that the composition is relatively similar to that of cement raw materials, and modified this steel slag to use it as a cement raw material, especially as a super-fast hardening cement raw material. Attempts have been made to use it.

For example, in Japanese Patent Publication No. 57-34223, CaO = 68-72%, Fe203
=0.2~1.0%, SiO2=22~26%,
P205=0.1~0.6%, Al203=1~
3%, TiO2=0.4-0.9%, MnO=0
．． 4% or less, CaF2=0.3-2.0%, Mg
It has a composition consisting of O = 0.3 to 3.0%, and its mineral structure mainly exists in the form of 3CaO・SiO2.
A method for producing steel slag cement, which is obtained by modifying steel slag, is disclosed, which is characterized in that almost no 3CaO.Al203 is present. This is Al203 in the steel slag cement component.
11CaO・7Al20
It is similar to so-called early-strength cement, which has almost no mineral structure of 3.CaF2.

[0004] Japanese Patent Application Laid-open No. 63-206336 describes a method for producing quick-hardening cement using dephosphorized slag, in which an alumina source and a lime source are blended with dephosphorized slag powder, which has been magnetically separated to remove metallic iron. Baked at 850-1250℃, 11
A method is described in which a clinker containing CaO.7Al203.CaF2 as a main component is produced, the clinker is pulverized, and then gypsum is added to form a quick-hardening cement. The cement produced by this method has low ultra-rapid hardening, and the 1 hour compressive strength in the JIS mortar test is 2 to 6 kg/cm2. This compressive strength is 1/6 or less, which is much lower than that of jet cement, which is a commercially available ultra-fast hardening cement, at 35 to 40 kg/cm2. In addition, since dephosphorization slag after magnetic separation is used as a raw material, the sensible heat of hot slag cannot be used effectively, resulting in high manufacturing costs.
Since it cannot be removed, there are also problems in that the strength of the cement decreases and the color of the cement becomes brownish.

[0005] Japanese Patent Application Laid-Open No. 2-236214 discloses that lime, limestone,
By mixing one or more of iron oxide, fluorite, aluminum, aluminum dross, alumina waste, bauxite, and aluminum hydroxide, the slag component is expressed in weight percent: CaO=
35-45%, Al203 = 25-35%, and the main component of the solidified slag component is 12CaO・7Al203
Alternatively, a method for modifying steel slag is described, which is characterized in that it is made into 11CaO.7Al203.CaF2. The obtained modified slag is used as a quick-setting agent and a raw material for ultra-fast hardening cement. Since this reforming method is carried out during refining, it is not possible to reduce the slag before the slag reforming process. Therefore, the obtained modified slag is F
Contains a large amount of iron such as eO and Fe203, and also contains Mn.
Since it contains a large amount of O 2 , it is necessary to remove iron by magnetic separation treatment in the post-process, which makes the operation even more complicated. Furthermore, it is impossible to remove MnO from the slag, and as mentioned above, the presence of MnO causes problems such as inhibition of cement strength and brownish color of the cement.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a raw material for ultra-rapid hardening cement by modifying steel slag, which does not have the above-mentioned problems. More specifically, it is an object of the present invention to provide a method that can produce an ultra-fast hardening cement raw material of excellent quality without performing magnetic separation through a reforming process that effectively utilizes the sensible heat of heated steel slag.

[0007]

[Means for Solving the Problems] The present inventors have developed a method for producing steel slag by directly transferring CaF2-containing hot steel slag generated in the pretreatment process or refining process to a container such as a pot, immediately adjusting the composition, and firing it. 11Ca by effectively utilizing the sensible heat of the slag
It is possible to produce an ultra-fast hardening cement raw material (clinker) whose main component is O・7Al203・CaF2, and if a reducing agent such as carbon is added to hot steel slag before reduction treatment, FeO, Fe203, MnO, Mn2O3 can be produced.
can be separated by specific gravity as ferroalloy (Fe-Mn).
It has been found that it is possible to produce a high quality ultra-fast hardening cement raw material that does not contain e and manganese components.

The gist of the present invention is to mix an alumina source and a lime source with CaF2-containing hot steel slag generated during hot metal pretreatment or steelmaking process, and change the composition of the hot steel slag to CaF2.
3 to 10 moles of Al203 and 5 to 10 moles of CaO per 1 mole
After adjusting to 17 mol, this hot steel slag is 850 to 125
Calcinate at 0℃ to produce 11CaO・7Al203・CaF
The present invention provides a method for producing a raw material for ultra-rapid hardening cement by modifying steel slag, which is characterized by obtaining a product containing 2 as a main component. Preferably, a reducing agent is first added to the CaF2-containing hot steel slag, and 1
After melting and reducing at 300 to 1800°C, the precipitated ferroalloy is separated by specific gravity to obtain FeO+Fe203 content of 0.1 to 5% by weight and MnO+Mn203 content of 2.
．． After adjusting the components to 0% by weight or less, the above treatment is performed. In addition, the ferroalloy recovered by gravity separation can be used as an auxiliary raw material for steelmaking.

The steel slag to be treated in the present invention is not particularly limited as long as it is CaF2-containing slag generated during hot metal pretreatment or steel manufacturing process. A typical example is the dephosphorization slag produced in the dephosphorization process using fluorite as part of the solvent.
Other steel slags can also be used as long as they contain aF2. The amount of CaF2 in the steel slag is also not particularly limited, but in order to effectively generate the desired 11CaO 2 .7Al203.CaF 2 , it is preferable that the CaF 2 content is 3% by weight or more. As an alumina source, Al203
Any material that contains can be used. Examples of suitable alumina sources are aluminum ash, aluminum dross, aluminum, bauxite, aluminum hydroxide. Any material containing CaO 2 can be used as a source of lime. Preferred lime sources include quicklime, limestone, and slaked lime. Reducing agents include carbon or carbon sources (e.g. coke breeze, coal, pitch, electrode scraps), carbon monoxide (C
O), aluminum, hydrogen, etc. can be used.

0010

[Operation] The method of the present invention uses hot steel slag (molten steel slag) containing CaF2 generated during hot metal pretreatment or steelmaking process.
For example, hot steel slag containing CaF2 generated during dephosphorization treatment in a converter can be immediately transferred to an appropriate heating furnace.
This is preferable from the viewpoint of effective use of sensible heat. As the heating furnace, anything that can be heated by any method such as electricity, high frequency, gas, liquid or solid fuel can be used. For example, an electric furnace, a converter, a pot such as a ladle, etc. can be used.

In a preferred embodiment, first, the above-mentioned reducing agent is added to CaF2-containing hot steel slag to give a temperature of 1300 to 18
Heating to 00℃ to melt and reduce FeO and Fe in the steel slag
203, MnO, and Mn203 are reduced to produce ferroalloy (
Fe-Mn). The produced ferroalloy has a higher specific gravity than the steel slag, so it sinks to the bottom of the furnace, so it can be separated from the steel slag and recovered by gravity separation. As a result, FeO+F in the steel slag
e203 content is 0.1-5% by weight, MnO+Mn
203 Adjust the ingredients so that the content is 2.0% by weight or less. The reason for performing this reduction process is as follows.

[Fe203 in cement] Fe203
Acts as a solvent in cement production, facilitating the firing and combination of cement raw materials, and plays an important role in imparting the unique color of cement. However, Fe203 is 11CaO・7Al203・C
Since it has the function of suppressing the hydration of aF2 and 3CaO/SiO2, it is important to keep the iron oxide content low in ultra-fast hardening cement. Therefore, in ultra-fast hardening cement, the Fe203 content should be set to 0.1~
It is set at 2.0% by weight.

[MnO, Mn203 in cement]
In cement production, MnO (Mn203) inhibits cement strength by reducing the amount of 3CaO.SiO2 produced during firing. There is also the problem of browning the color of cement, and MnO (Mn203) in cement
) It is said that the lower the content, the better. According to a document published by the Japan Cement Association (Japan Cement Presentation Materials at the 35th Cement Technology Conference), if Mn203 exceeds 0.2%, a decrease in cement strength is observed.

[0014] For the above reasons, FeO, Fe in steel slag
203, MnO, Mn203 are removed, and FeO, Fe203, MnO, Mn2 in the produced clinker is
It is preferable to reduce 03. The reason why the smelting reduction method is adopted as a method for this purpose is that iron and manganese can be separated by a simple method called specific gravity separation, and the sensible heat of hot steel slag can be used as is. 11CaO・7Al2 is the main product in the modified clinker
In order to increase the amount of 03.CaF2 produced, it is necessary to set the calcination temperature to 1250° C. or lower, so the reduction treatment step must be performed before the calcination step of 11CaO.7Al203.CaF2. In addition, the reduction treatment temperature should be higher than the melting temperature of steel slag and C
Since it is necessary to keep the temperature below which aO and Al203 are not reduced, the temperature is set in the range of 1300 to 1800°C. The preferable reduction treatment temperature is 1400 to 1700°C.
It is. This reduction treatment results in FeO+Fe203 content of 0.1 to 5% by weight and MnO+Mn203 content of 2
．． Adjust the ingredients to 0% by weight or less. If the content of iron oxide and manganese oxide in the steel slag is reduced within this range, Fe203 content of ultra-fast hardening cement obtained by blending gypsum and Portland cement with clinker modified by the method of the present invention can be reduced. It becomes possible to adjust the amount and MnO (Mn203) content within the above range, resulting in an ultra-fast hardening cement with excellent quality.

[0015] Ferroalloy (Fe-Mn) separated and recovered from steel slag by specific gravity separation is useful as ferromanganese for various uses. For example, it can be effectively used as an auxiliary raw material for steel manufacturing and the like for deoxidation and other purposes. Thereby, substantially all of the components of the steel slag can be effectively reused without producing waste, contributing to both environmental protection and resource conservation.

Preferably, after adjusting the content of iron oxide and manganese oxide by reduction treatment as described above, 11C
In order to produce an ultra-fast hardening product whose main components are aO.7Al203.CaF2, an alumina source and a lime source are added to the hot steel slag after reduction to adjust the composition, and then fired. It is convenient to carry out this calcination using the same furnace used in the reduction step. That is, after the reduction treatment in a suitable heating furnace, an alumina source and a lime source are immediately added to the hot steel slag in the heating furnace from which the ferroalloy has been separated by specific gravity separation.
Firing is performed at 850-1250°C. In this case, the heating furnace is equipped with hoppers for supplying reducing agent, alumina source, and lime source, as shown in Figure 1, and clinker (reformed steel slag) is installed on the side of the heating furnace from above. It is convenient to provide an outlet and a ferroalloy outlet to perform specific gravity separation of the ferroalloy. Of course, the calcination can also be carried out in a separate container from the reduction step.

The components in the steel slag after blending are 3 to 10 moles of Al203, preferably 5 to 8 moles of Al203 per 1 mole of CaF2.
mol, CaO 5 to 17 mol, preferably 7 to 13 mol. In order to maximize the production amount of 11CaO・7Al203・CaF2, about 7 mol of Al203, Ca
About 11 moles of O is most preferred. The firing temperature is 850
~1250°C. Outside this range, 11CaO・7
The production efficiency of Al203/CaF2 decreases. The preferred firing temperature is 900-1200°C.

[0018] 11CaO modified by this calcination
The product whose main components are 7Al203 and CaF2 is recovered from the heating furnace to obtain an ultra-fast hardening cement raw material (clinker). This clinker is mixed with gypsum and Portland cement and used as an ultra-fast hardening cement. The blending amounts of gypsum and Portland cement are adjusted taking into account quick hardening and cement strength, but usually the clinker obtained by the method of the present invention is 20 to 40%, gypsum is 10 to 25%, and Portland cement is 35 to 70% by weight. Within the range of %.

Next, the present invention will be further explained with reference to Examples. In the examples, % is by weight unless otherwise specified.

[Example] As shown in Fig. 1, an electric furnace was used, which was equipped with hoppers and quantitative cutting devices for reducing agent, alumina source, and lime source, and with outlet ports for clinker and ferroalloy on the side. , dephosphorization slag generated in a converter was modified by the method of the present invention. Table 1 shows the compositions of the dephosphorization slag, reducing agent (coke powder), alumina source (aluminum ash), and lime source (quicklime) used.

After the dephosphorization process is completed in the converter, in order to effectively utilize the heat source of the slag, the dephosphorization slag is immediately transferred to an electric furnace, and coke breeze is added as a reducing agent to the total amount of slag and coke breeze. The mixture was added in an amount of 10%, heated to the reduction temperature shown in Table 2, and kept heated for 1 hour for reduction treatment. At the end of this heat retention, the ferroalloy that had settled to the bottom of the furnace was discharged from the ferroalloy outlet at the lower part of the side of the furnace and separated from the molten slag by specific gravity. Next, aluminum ash and quicklime were added to the molten slag in the amounts shown in Table 3 from each hopper, and the slag was fired at the firing temperature shown in Table 3 for 3 hours to obtain clinker, which is a raw material for ultra-fast hardening cement.

Table 2 shows the reduction treatment conditions and reduction results (FeO+Fe203 and Mn in the molten slag after specific gravity separation).
O+Mn203 content and melting state) are shown. As the reduction temperature increases, FeO+Fe2 in the slag after reduction treatment
03 and MnO+Mn203 are both decreasing. However, the higher the reduction temperature, the higher the production cost, so the reduction temperature may be determined based on the components of the slag used and the target composition of the final clinker after reformation. However, as shown in the comparative example, melt specific gravity separation is not possible at a treatment temperature of less than 1300°C, and when it exceeds 1800°C, CaO
and Al203, ultimately 11
Since the amount of CaO.7Al203.CaF2 produced is extremely reduced, the object of the present invention cannot be achieved.

Table 3 shows the firing treatment conditions and results (content of 11CaO.7Al203.CaF2 in the fired clinker). The firing temperature was preferably 850 to 1250°C, with the best results being around 1200°C. Outside this range, 11CaO 2 .7Al203 .CaF 2 will not be efficiently produced. Regarding the blending amount of CaO and Al203, it is 3-1% of Al203 per 1 mole of CaF2.
0 mol, CaO within the range of 5 to 17 mol, 11CaO
・A clinker whose main component is 7Al203・CaF2 is obtained, and outside this range, 11CaO・7Al
The amount of 203.CaF2 produced becomes extremely small. CaO
The best results were obtained with approximately 11 mol of Al203 and approximately 7 mol of Al203, but the blended amount of the alumina source and lime source was 11 Ca.
It may be determined based on the relationship between the target production amount of O.7Al203.CaF2 and manufacturing cost.

[Mortar compressive strength test] The above fired clinker was milled with a specific surface area of 4000 cm2 in a ball mill.
/g powder was blended with the conditions and combinations shown in Table 4 (the ultra-fast hardening raw material was 4000
cm2/g powder, anhydrite (CaSO4) is a commercially available product, Portland cement is a commercially available ordinary Portland cement), FeO+Fe2 in the cement composition after blending.
03 and MnO+Mn203 contents were investigated. The results are shown in Table 4. Next, mortar specimens specified in JIS R 5201 were prepared, and the compressive strength was examined. The results are shown in the same table. In addition, the comparative examples in the table include an example using a super-fast hardening raw material that has been calcined without reduction, and the compressive strengths of ordinary Portland cement (commercial product) and jet cement (commercially available super-fast hardening cement). The ultra-fast hardening cement using the raw material modified by the method of the present invention showed performance equivalent to that of commercially available products.

[0024]

[Table 1]

[0025]

[Table 2]

[0026]

[Table 3]

[0027]

[Table 4]

[0028]

Effects of the Invention According to the present invention, the sensible heat of molten steel slag containing CaF2, which was conventionally disposed of as landfill, can be effectively used to economically produce high value-added ultra-fast hardening cement. (clinker) is manufactured. Moreover,
By combining reduction treatment, Fe content in steel slag, M
The n component can be removed and recovered as ferroalloy (Fe-Mn), and clinker with excellent quality such as strength and color can be obtained. At the same time, the recovered ferroalloy can be effectively used as an auxiliary raw material for steelmaking, etc. Therefore, all components of steel slag can be effectively utilized. Therefore, the method of the present invention not only makes effective use of resources, but also provides an extremely excellent industrial effect in that ultra-fast hardening cement, which has conventionally been relatively expensive, can be supplied at a lower cost. .

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a heating furnace that can be used in the method of the present invention.

Claims (3)

[Claims] Claim 1: Adding an alumina source and a lime source to CaF2-containing hot steel slag generated during hot metal pretreatment or steelmaking process, the composition of the hot steel slag is adjusted to 1 mole of CaF2 to 1 mole of Al20.
3 to 10 moles and CaO to 5 to 17 moles, this hot steel slag was calcined at 850 to 1250°C to obtain 11
A method for producing a raw material for ultra-fast hardening cement by modifying steel slag, characterized by obtaining a product containing CaO.7Al203.CaF2 as a main component. [Claim 2] A reducing agent is added to CaF2-containing hot steel slag generated during hot metal pretreatment or steelmaking process to give a temperature of 1300 to 18
After melting and reducing at 00°C, the precipitated ferroalloy is separated by specific gravity to obtain FeO+Fe203 content of 0.1
~5% by weight, MnO + Mn203 content 2.0% by weight or less, and then an alumina source and a lime source are added to this hot steel slag, and the composition is adjusted to 1 mole of CaF2, 3 to 10 moles of Al203, CaO After adjusting the amount to 5 to 17 moles, this heated steel slag is fired at 850 to 1250°C to obtain a product whose main components are 11CaO, 7Al203, and CaF2. A method for producing hard cement raw materials. 3. The method according to claim 2, wherein the ferroalloy recovered by gravity separation is used as an auxiliary raw material for steelmaking.