JP2009227488A - Method for manufacturing cement raw material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture a slag for a cement raw material from steel making slag at low cost without special treatment such as secondary heat treatment and the like to the slag after cooling. <P>SOLUTION: In a cooling step of the steel making slag generated in a steel making step and having a slag basicity (mass ratio: %CaO/%SiO<SB>2</SB>) of 2 or more, cooling is performed at an average cooling speed from 1,000 to 700°C of 10 °C/min or more. C<SB>3</SB>S existing in high temperature slag can be kept after cooling without being decomposed to C<SB>2</SB>S and CaO by controlling and optimizing cooling speed in a specific high temperature range and then high cement activity as the cement raw material can be obtained due to the C<SB>3</SB>S. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for producing a cement raw material from slag generated in a steel making process.

  In the steel making process of the iron making process, phosphorus, sulfur, carbon, etc. contained in the hot metal are removed, and the content of trace elements is adjusted according to the use of the steel. In the refining process for that purpose, a refining agent such as lime or iron oxide is used, and steel slag is generated as a by-product. This steelmaking slag is broadly classified into hot metal pretreatment slag that is generated in each refining process of desiliconization, dephosphorization, and desulfurization called hot metal pretreatment, and decarburization slag that is generated in decarburization refining process. These steelmaking slags are used mainly for roadbed materials, earthwork materials, marine earth and lumber, etc., and are also being reused in the steelmaking process.

  On the other hand, a cement raw material is considered as one of the uses of steelmaking slag. Regarding such applications, for example, Patent Document 1 proposes a steelmaking slag treatment method suitable for a cement raw material, and Patent Document 2 also proposes a cement production method using steelmaking slag. If steelmaking slag can be used as a cement raw material, CaO contained in a large amount in steelmaking slag can be effectively used for cement, and resource saving can be achieved for natural raw materials such as limestone. However, in the case of blast furnace slag, it can be used as a mixed cement just by mixing with other raw materials at room temperature, whereas in the case of steelmaking slag, it is necessary to mix with other raw materials and then kiln firing, It cannot fully meet social demands such as reduction of carbon dioxide emissions and energy saving.

The reason why firing is necessary when steelmaking slag is used as a cement raw material is that the CaO-containing mineral contained in the steelmaking slag does not have high activity as a hydration reaction product such as cement. When attention is paid to slag basicity [mass ratio:% CaO /% SiO ₂ ] (hereinafter simply referred to as “basicity”), steelmaking slag generally has a basicity of 1 or more, particularly those having a basicity of 2 or more. It is expected that components that cause a cement reaction such as 2CaO.SiO ₂ (C ₂ S) and 3CaO.SiO ₂ (C ₃ S) are included. However, since many steelmaking slags contain phosphorus, C ₂ S in the slag has a stable structure as β-C ₂ S, and such C ₂ S is almost expected to have a reaction activity as a cement. Can not. C ₃ S is decomposed into C ₂ S and CaO in the process of cooling from the molten slag, and is not so much contained in the steelmaking slag at room temperature.

For this reason, even if steelmaking slag is simply pulverized and mixed at room temperature, the function as a cement raw material is not so much manifested. Patent Document 3 discloses a cement composition in which Portland cement, blast furnace slag fine powder, and dephosphorized slag fine powder containing apatite calcium are mixed at room temperature. However, fluorine content is essential, and Since it is desirable to pre-treat the dephosphorization slag, it is necessary to separately process the steel slag that is usually generated, which is not an economical method.
JP 2001-48605 A US Pat. No. 6,491,751 JP 2005-29404 A

  Therefore, the object of the present invention is to solve such problems of the prior art and produce a cement raw material from steelmaking slag at low cost without subjecting the slag after cooling to a special treatment such as secondary heat treatment. It is to provide a method that can.

The present inventors have conducted a detailed study on a method capable of enhancing the cement activity (reaction activity as cement) of steelmaking slag without performing a special treatment. First, it is considered that C ₃ S, 3CaO · P ₂ O ₅ , 3CaO · Al ₂ O _{3 and the} like are precipitated from the molten steelmaking slag, and in this case, in particular, C ₃ S is C ₂ S and CaO. However, it was found that the decomposition condition changes depending on the conditions for cooling the steelmaking slag, and the characteristics as a cement raw material change. And, in the cooling process of the steelmaking slag generated in the steelmaking process, it was found that the cement activity of the steelmaking slag at room temperature can be effectively increased by controlling and optimizing the cooling conditions in a specific temperature range. .

  Furthermore, it has been found that high-temperature oxidation occurs by using water (watering cooling) in the cooling, and a composition suitable for cement is obtained. In addition, by separating finely pulverized slag after cooling under specific particle size conditions, and further optimizing fine pulverization conditions, metal iron that does not contribute to the cement reaction can be appropriately separated and removed. It was found that high-quality cement raw materials can be produced economically and metal iron can be recovered appropriately.

The present invention has been made on the basis of the above-described findings and has the following gist.
[1] steelmaking slag basicity generated by: the mass ratio% CaO /% SiO _2] the cooling process of two or more steel slag, from 1000 ° C. to 700 ° C. at an average cooling rate of 10 ° C. / min or more A method for producing a cement raw material, characterized by cooling.
[2] A method for producing a cement raw material according to the above [1], wherein water is sprayed on steel slag to cool from 1000 ° C. to 700 ° C. at an average cooling rate of 10 ° C./min or more.

[3] In the manufacturing method according to [1], a rotatable horizontal cooling drum through which a refrigerant is passed is provided, and the molten slag is cooled by contact with the outer peripheral drum surface, and the cooled slag is drum A cement raw material characterized in that a steelmaking slag is cooled from 1000 ° C. to 700 ° C. at an average cooling rate of 10 ° C./min or more by using a molten slag cooling treatment apparatus which is separated from the surface and discharged. Manufacturing method.
[4] The method for producing a cement raw material according to any one of the above [1] to [3], wherein the steelmaking slag is decarburized slag.

[5] In the production method according to any one of [1] to [4] above, the steelmaking slag is sprinkled and cooled so that the component ratio (mass ratio) of iron oxide contained in the slag is FeO / Fe ₂ O ₃ ≦ 2. A method for producing a cement raw material, wherein
[6] In the production method according to any one of [1] to [5], the cooled steelmaking slag is finely pulverized and then sieved to obtain a cement raw material having a particle size of 45 μm or less. Production method.
[7] In the production method according to any one of [1] to [5] above, the cooled steelmaking slag is finely pulverized so that 90 mass% or more of the iron oxide contained in the slag has a particle size of 45 μm or less, and then sieved. A method for producing a cement raw material, characterized in that a cement raw material having a particle size of 45 μm or less is recovered and a particle size of more than 45 μm is recovered as ground iron.

According to the present invention, a cement raw material can be stably produced from steelmaking slag at low cost without subjecting the slag after cooling to a special treatment such as secondary heat treatment.
Further, in the present invention, by cooling the steelmaking slag with water, it is possible to rapidly cool a specific temperature range at an appropriate cooling rate, and at the same time, the FeO in the slag is oxidized at high temperature to be changed to Fe ₂ O _3. The slag composition can be particularly suitable as a cement raw material.
Further, in the present invention, by cooling the steelmaking slag using a specific cooling processing device equipped with a horizontal cooling drum, the molten slag is brought into contact with the drum surface in a thin state, thereby appropriately cooling a specific temperature range. Can be rapidly cooled at speed.
Further, in the present invention, by optimizing the component ratio [FeO / Fe ₂ O ₃ ] of iron oxide contained in the slag by sprinkling and cooling the steelmaking slag, a slag composition more suitable as a cement raw material is obtained. Can do.
In the present invention, after the cooled steelmaking slag is finely pulverized, it is sieved to obtain a cement raw material having a predetermined particle size or less, more preferably after the cooled steelmaking slag is finely pulverized under specific conditions. By sieving and using a cement raw material having a predetermined particle size or less as the cement raw material, it is possible to appropriately separate and recover the inert metal iron as the cement raw material, while obtaining a high-quality cement raw material.

The present invention, slag basicity generated in the steelmaking process [mass _{ratio:% CaO /% SiO 2]} ( hereinafter, simply referred to as "basicity") in the cooling process of two or more steelmaking slag, 700 ° C. from 1000 ° C., Preferably, cooling is performed up to 600 ° C. at an average cooling rate of 10 ° C./min or more, preferably 15 ° C./min or more. Such a cooling rate is a considerably high cooling rate as compared with that of standing to cool, and therefore, in the following description, cooling by the above cooling rate may be referred to as rapid cooling.
The slag temperature (including the cooling rate) defined in the present invention is the center temperature in the slag thickness direction. In order to obtain such a thickness-direction center temperature, for example, the correspondence between the slag surface temperature and the thickness-direction center temperature in consideration of factors such as slag type, slag thickness, cooling conditions, ambient atmosphere, and temperature. The relationship is obtained in advance, and based on this correspondence, the thickness direction center temperature can be obtained from the measured value of the slag surface temperature.

Examples of the steelmaking slag targeted by the present invention include hot metal pretreatment slag such as dephosphorization slag and desulfurization slag, and decarburization slag generated in a decarburization furnace such as a converter. Any type of steelmaking slag having a basicity of 2 or more can be used. Among these, decarburized slag is particularly preferable because it has a high CaO ratio and contains CaO and SiO ₂ as main components, and can be expected to have high performance as a cement raw material.
When the basicity of the steelmaking slag is less than 2, C ₂ S is precipitated from the initial crystallization stage, and high cement activity cannot be ensured. However, if the basicity exceeds 5, a large amount of free CaO called free-CaO is generated from the molten state and it is difficult to ensure volume stability when used as cement. The degree is preferably 5 or less.

Conventionally, the steelmaking slag generated in the steelmaking process is allowed to cool in a cooling yard, and water is sprayed when the temperature drops considerably. When steelmaking slag is cooled by such a general method, since the amount of sensible heat of the slag is large, cooling does not easily proceed. The present inventors considered that the situation where the cooling of the slag does not proceed in this way has an adverse effect on the cement activity, and conducted the following tests and investigations. That is, water cooling is performed from 1450 ° C. to steelmaking slag having a basicity of 4.0 (decarburized slag), rapidly cooled to various temperatures, held at that temperature, and then naturally cooled in an electric furnace. The relationship between the temperature rapidly cooled by watering (slag temperature at the time of quenching by watering) and the characteristics of slag was investigated. The phenomenon that C ₃ S decomposes into C ₂ S and CaO is difficult to grasp by X-ray, etc., so steam aging is applied to the slag after cooling, and the pulverization behavior (slag pulverization rate) is evaluated. It was. This is because when steam aging is applied, a phenomenon is observed in which the volume expansion of CaO becomes Ca (OH) ₂ and the slag is pulverized. FIG. 1 shows the relationship between the slag temperature at the end of quenching by sprinkling cooling (average cooling rate: 15 ° C./min) and the slag powdering rate when steam aging is performed in the above test. According to this, by rapidly cooling to 700 ° C., the slag powdering rate is greatly reduced, and when rapidly cooled to 600 ° C., the powdering phenomenon is not observed.

C ₃ S in the steelmaking slag is stable in a high temperature range exceeding 1000 ° C., but when it is 1000 ° C. or less, it is considered that the decomposition into C ₂ S and CaO becomes more stable. However, as long as it is a decomposition reaction, activation energy and diffusion of components in the particles are involved, and as a result, the progress of the reaction is hindered without a certain amount of temperature energy. That is, if it is rapidly cooled to 1000 ° C. or more and 700 ° C. or less, preferably 600 ° C. or less, the progress of the decomposition reaction can be suppressed, and C ₃ S in the slag can be maintained. Conceivable.
When the temperature at which the rapid cooling is started is less than 1000 ° C., each particle grows before the start of cooling, and the particles of free CaO that cause pulverization become large and pulverization easily proceeds, or the decomposition of C ₃ S Progresses, and the powdering rate becomes high.

Further, when the average cooling rate is less than 10 ° C./min, the cement activity of the slag cannot be sufficiently increased. FIG. 2 shows a cooling process of steelmaking slag (decarburization slag) having a basicity of 3.7 from 1000 ° C. to 600 ° C. at various average cooling rates (average cooling rates of 10 ° C./min and 15 ° C./min are Sprinkling cooling, average cooling rate of 5 ° C / min is controlled by controlling the temperature in the furnace, and then cooling is performed, the average cooling rate and slag powdering rate (slag when steam aging similar to Fig. 1 is applied) This shows the relationship with the pulverization rate. According to this, when the average cooling rate is 10 ° C./min or more, the slag powdering rate is remarkably reduced, and especially when the average cooling rate is 15 ° C./min or more, the pulverization phenomenon is hardly observed.
For the above reasons, in the present invention, the steelmaking slag is cooled from 1000 ° C. to 700 ° C., preferably 600 ° C., at an average cooling rate of 10 ° C./min or more, preferably 15 ° C./min or more.

The method of cooling the steelmaking slag generated in the steelmaking process at an average cooling rate of 10 ° C./min or more (preferably 15 ° C./min or more) in the cooling process is not particularly limited. (B) A rotatable horizontal cooling drum through which a refrigerant is passed is provided, and the slag is cooled by contacting the molten slag with the outer drum surface, and the cooled slag is removed from the drum surface. A method for cooling steelmaking slag using a molten slag cooling apparatus that is peeled and discharged can be applied.
In the method (a), a large cooling rate is obtained by the latent heat of vaporization of the sprinkled water, and in the method (b), the slag is cooled by contacting the drum surface in a relatively thin state. Even in this case, a large cooling rate can be obtained.
In addition, the (b) cooling method includes, for example, a cooling mode using a cooling processing apparatus as described below.

(A) A cooling processing apparatus including a single horizontal cooling drum and a gutter that supplies molten slag to the horizontal cooling drum.
(B) Cooling provided with a pair of horizontal cooling drums arranged in parallel, each of which has a rotating direction in which opposing outer peripheral portions rotate upward, and molten slag is supplied from above between the upper outer peripheral surfaces of the pair of horizontal cooling drums Processing equipment.
(C) A pair of horizontal cooling drums having a rotation direction in which the opposing outer peripheral portions rotate downward with a gap therebetween are provided, and molten slag is formed between the upper outer peripheral surfaces of the pair of cooling drums from above. Cooling processing device supplied.
The details of the cooling processing apparatuses (a) to (c) and the cooling mode by this will be described later.

  Even in the case of water spray cooling, if the thickness of the slag to be cooled is reduced, the cooling rate can be increased accordingly. From this point of view, it is particularly effective to perform the water spray cooling with a slag thickness of 300 mm or less. About steelmaking slag (decarburized slag) with a basicity of 3.5, the slag thickness was changed and sprinkled cooling was performed under the conditions of the present invention. 30 mass% was replaced with slag), and the compressive strength of the mortar with this mixed cement was examined. FIG. 3 shows the relationship between the slag thickness and the compressive strength of the mortar when sprayed and cooled, and it can be seen that a high mortar strength can be obtained particularly when the slag thickness is 300 mm or less.

Moreover, when high-temperature steelmaking slag is sprinkled and cooled, it can be expected that the oxidation ability of water will be expressed, and it is also effective to sprinkle water to promote it. That is, among the components in the slag, there is iron oxide as a property expected to be changed by oxidation. Iron oxide is usually present as FeO in steelmaking slag, and a part thereof is present as Fe ₂ O ₃ . Even if water is sprinkled on steelmaking slag at room temperature or near room temperature, FeO in the slag is hardly oxidized, but by sprinkling water on the slag with heat energy to promote oxidation, FeO is changed to Fe ₂ O ₃ Can be made. Fe ₂ O ₃ is an advantageous component for fixing free CaO, and is also known as a mineral constituting a hydration reaction product of cement. Therefore, the performance as a cement raw material can be improved by oxidizing FeO by water-cooling high-temperature steelmaking slag and changing it to Fe ₂ O ₃ .

For steelmaking slag with basicity 3.5 (decarburized slag), when water spray cooling was performed under the conditions of the present invention, the progress of oxidation of FeO to Fe ₂ O ₃ was changed, and cooling was completed (slag slag) Was mixed in cement with 30 mass% (30 mass% of Portland cement was replaced with slag), and the compressive strength of the mortar with this mixed cement was examined. FIG. 4 shows the relationship between the component ratio [FeO / Fe ₂ O ₃ ] (mass ratio) of iron oxide in the slag after cooling and the compressive strength of the mortar, and the mortar strength increases as the proportion of Fe ₂ O ₃ increases. In particular, a high mortar strength is obtained when FeO / Fe ₂ O ₃ ≦ 2, and the highest mortar strength is obtained when FeO / Fe ₂ O ₃ ≦ 1.6.
For this reason, in this invention, the steel oxide slag is sprinkled and cooled so that the component ratio (mass ratio) of iron oxide contained in the slag is FeO / Fe ₂ O ₃ ≦ 2, preferably FeO / Fe ₂ O ₃ ≦ 1. 6 is desirable.

  The particle size of the cement raw material slag produced according to the present invention is not particularly limited, but when considering use as a part of the mixed cement, general cement raw materials (ordinary Portland cement, granulated blast furnace slag, etc.) ) Is preferred for quality stability. From this viewpoint, it is preferable that the cooled steelmaking slag is finely pulverized and then sieved to obtain a particle size of 45 μm or less as a cement raw material. Here, the particle size of 45 μm or less is the particle size of the slag under the sieve when sieved using a sieve having a nominal size of 45 μm among the sieves defined in JIS R 8801.

  Steelmaking slag usually contains about 1 to 15 mass% of metallic iron. Even in the current process, large bullion (bullion: separated from slag for the purpose of recovering metallic iron and mainly containing metallic iron) is removed by magnetic separation and recovered bullion. Is reused in the steelmaking process. However, the bullion taken into the slag is directly used as part of the slag. In the production method of the present invention, when the slag after cooling is finely pulverized, the metallic iron is not crushed by ordinary mechanical pulverization and remains as granular iron. When the present inventors investigated how metal iron is separated when the slag after pulverization is sieved with a sieve having a nominal size of 45 μm, 90 mass% or more of the slag remains on the sieve. confirmed. Therefore, after sufficiently cooling the slag after cooling, and sieving with a sieve having a nominal size of 45 μm, the metal iron can be efficiently recovered as slag on the sieve.

In order to effectively use the metal in the steelmaking slag in the iron making process, it is desirable to reduce the iron oxide content contained in the recovered metal as low as possible. For this reason, after pulverizing the cooled steelmaking slag so that 90 mass% or more of the iron oxide contained in the slag has a particle size of 45 μm or less, it is preferable to sieve and use the particle size of 45 μm or less as a cement raw material, As a result, a particle size of more than 45 μm can be recovered as a high-quality metal.
Steelmaking slag with a basicity of 3.5 (decarburized slag) is cooled under the conditions of the present invention, the slag after cooling is pulverized with various pulverization times, and then sieved with a sieve having a nominal size of 45 μm. The relationship between the metal iron content of slag and the iron oxide transfer rate to the slag (the ratio of the amount of iron oxide in the slag to the total amount of iron oxide in the slag) and the grinding time were investigated. The result is shown in FIG. According to this, when the slag is finely pulverized with sufficient pulverization time, the amount of iron oxide transferred to the under-sieving slag increases, while the metallic iron content of the above-sieving slag increases.
When the amount of iron oxide transferred to the sieving slag becomes 90 mass% or more, the content of metallic iron in the slag on the sieve becomes approximately 65 mass%, and this can be recovered as high-grade metal.

Next, an outline of each type of the cooling processing apparatus (a) to (c) described above and the cooling mode by this will be described with reference to the embodiment of FIGS.
FIG. 6 is an explanatory view showing an embodiment of the cooling processing apparatus of the type (a). This cooling processing apparatus is a single rotatable horizontal cooling drum 1e (hereinafter, simply referred to as “cooling drum”, the same applies to other embodiments) that cools by adhering molten slag to the outer drum surface 100. The cooling drum 1e is provided with a gutter 2 for supplying molten slag.

The flange 2 is disposed on one side in the radial direction of the cooling drum and is provided so that its tip end is in contact with or close to the drum surface 100 of the cooling drum 1e. Thus, the slag liquid reservoir A is formed, and the molten slag S in the slag liquid reservoir A adheres to the drum surface 100 and is taken out as the cooling drum 1e rotates.
The cooling drum 1e is rotationally driven by a driving device (not shown) so that the upper drum surface rotates in a rubbing direction.

Moreover, in this embodiment, it has the rolling roll 3 for rolling the molten slag adhering to the drum surface 100 of the cooling drum 1e, and extending it in a drum width direction. The cooling processing apparatus provided with such a rolling roll 3 is suitable for cooling processing of molten slag having a particularly high basicity of 2 or more. That is, molten slag having a relatively high basicity, such as converter decarburization slag, has a high viscosity, and when such a highly molten slag is cooled by a cooling drum type slag cooling processing apparatus, For this reason, it is difficult for the molten slag to adhere uniformly to the cooling drum surface, and the cooling process using the entire drum surface effectively cannot be performed. For this reason, the cooling efficiency of molten slag is low and high productivity cannot be obtained. Also, slag with high basicity (especially basicity ≧ 3) is easily pulverized, and such slag can be made difficult to pulverize by quenching from a molten state, but it is cooled by a conventional slag cooling treatment device. When processed, the thickness cannot be reduced due to high viscosity, and a sufficient cooling rate cannot be obtained, so that powdering after cooling cannot be appropriately suppressed. In order to deal with such a problem, in the present embodiment, a rolling roll 3 is provided for rolling the molten slag adhering to the drum surface 100 of the cooling drum 1e and extending it in the drum width direction.
The rolling roll 3 is arranged on the upper part of the cooling drum 1e so as to be parallel to the cooling drum 1e and to form a predetermined interval with the drum surface 100 of the cooling drum 1e, and is rotatably supported.

  In the cooling treatment of the molten slag using the cooling treatment apparatus as described above, the molten slag S supplied to the trough 2 flows into the slag liquid reservoir A, where it is cooled by staying for an appropriate time, The cooling drum 1e is taken out by adhering to the drum surface 100, and is cooled to an appropriate solidified state (for example, a semi-solid state or a state where only one or both surface layers are solidified) while adhering to the drum surface 100. At that time, the molten slag S adhering to the drum surface 100 is rolled in the drum width direction by being rolled by the rolling roll 3. The cooled slag naturally peels from the cooling drum surface by its own weight at a predetermined drum rotation position.

FIG. 7 is an explanatory view showing an embodiment of the cooling processing apparatus of the type (b).
This cooling processing apparatus includes a pair of cooling drums 1a and 1b arranged in parallel, each of which has a rotation direction in which opposing outer peripheral portions rotate upward, and from above between the upper outer peripheral surfaces of the pair of cooling drums 1a and 1b. Molten slag S is supplied.
The cooling drums 1a and 1b are rotationally driven in the rotational direction by a driving device (not shown). Further, on the upper part of the cooling drums 1a and 1b, rolling rolls 3a and 3b similar to those in the embodiment of FIG. 1 are provided in parallel with the cooling drum.

  In the cooling processing apparatus of the present embodiment, the molten slag S is supplied from the slag gutter 4 between the upper outer peripheral surfaces of the cooling drums 1a and 1b (the concave portions having a V-shaped cross section) whose opposing outer peripheral portions rotate upward. A liquid reservoir Sa is formed. The molten slag S is cooled by staying in the slag liquid reservoir Sa for an appropriate time, and then taken out of the slag liquid reservoir Sa by adhering to the surfaces of the rotating cooling drums 1a and 1b. The molten slag S is rolled by the rolling roll 3 and cooled to an appropriate solidified state (for example, a semi-solid state or a state in which only the surface layer is solidified) while adhering to the cooling drum surface, and then at a predetermined drum rotation position. It peels naturally from the cooling drum surface by its own weight.

FIG. 8 is an explanatory view showing an embodiment of the cooling processing apparatus of the type (c).
This cooling processing apparatus is provided with a pair of cooling drums 1x and 1y that are arranged in parallel with a gap and whose outer peripheral portions rotate in a downward direction, and the upper outer periphery of the pair of cooling drums 1x and 1y. Molten slag S is supplied between the surfaces from above. The cooling drums 1x and 1y are rotationally driven in the rotational direction by a driving device (not shown).
In the cooling processing apparatus of the present embodiment, the molten slag S is supplied from the slag gutter 4 between the upper outer peripheral surfaces of the cooling drums 1x and 1y whose opposing outer peripheral portions rotate downward (a concave portion having a V-shaped cross section). A liquid reservoir Sa is formed. The molten slag S is cooled by staying in the slag liquid reservoir Sa for an appropriate time, then flows into the gap g and is rolled while being cooled by the pair of cooling drums 1x and 1y, and then from the cooling drum surface. It peels and is discharged downward.

Steelmaking slag having the basicity, cooling conditions, and iron oxide component ratio after cooling as shown in Table 1 was finely pulverized, and sieved to select a particle size of 45 μm or less as a cement raw material. This was mixed with ordinary Portland cement at a ratio of 30 mass%, and the mixed cement was subjected to a mortar strength test defined by JIS R 5201 to examine the compressive strength after 7 days and 28 days. The results are shown in Table 1. In addition, the strength important for actually using concrete is the strength when 28 days or more have passed after construction.
According to Table 1, the mortar using the cement raw material of the example of the present invention has an excellent compressive strength with respect to the strength after 28 days. On the other hand, in the comparative example, although the strength after 7 days is expressed, the elongation of the strength thereafter is small and sufficient strength is not expressed.

A graph showing the relationship between the slag temperature quenched by watering (slag temperature at the end of quenching by watering) and the slag powdering rate when steam aging is performed in the steelmaking slag cooling process The graph which shows the relationship between the average cooling rate from 1000 degreeC to 600 degreeC in the cooling process of steelmaking slag, and the slag powdering rate at the time of performing steam aging A graph showing the relationship between the slag thickness when water spray is cooled and the compressive strength of mortar with mixed cement containing pulverized slag after cooling Graph showing component ratios of the iron oxide in the slag after watering cooling [FeO / Fe 2 O _3] and _(mass ratio), the relationship between the compressive strength of mortar by mixing cement formulated with pulverized slag after cooling When steelmaking slag is cooled under the conditions of the present invention, the slag after cooling is finely pulverized by changing the pulverization time, and when sieving, the iron content of the slag on the screen and the iron oxide transfer to the slag under the screen Graph showing the relationship between rate and grinding time Explanatory drawing which shows one Embodiment of the cooling processing apparatus which can be used by this invention Explanatory drawing which shows other embodiment of the cooling processing apparatus which can be used by this invention. Explanatory drawing which shows other embodiment of the cooling processing apparatus which can be used by this invention.

Explanation of symbols

1, 1e, 1a, 1b, 1x, 1y Horizontal cooling drum 2 樋 3, 3a, 3b Rolling roll 4 Slag 樋 A Slag liquid reservoir

Claims (7)

Slag basicity has occurred in the steelmaking process: in mass ratio% CaO /% SiO _2] the cooling process of two or more steel slag, cooling from 1000 ° C. to 700 ° C. at an average cooling rate of 10 ° C. / min or more A method for producing a cement raw material characterized by the above.   The method for producing a cement raw material according to claim 1, wherein water is sprayed on the steelmaking slag to cool from 1000 ° C to 700 ° C at an average cooling rate of 10 ° C / min or more.   A melt that is equipped with a rotatable horizontal cooling drum through which refrigerant is passed, and is cooled by the molten slag coming into contact with the outer drum surface so that the cooled slag is separated from the drum surface and discharged. The method for producing a cement raw material according to claim 1, wherein a steelmaking slag is cooled from at least 1000 ° C to 700 ° C at an average cooling rate of 10 ° C / min or more using a slag cooling treatment device.   The method for producing a cement raw material according to any one of claims 1 to 3, wherein the steelmaking slag is decarburized slag. 5. The component ratio (mass ratio) of iron oxide contained in the slag is set to FeO / Fe ₂ O ₃ ≦ 2 by water-cooling the steelmaking slag, according to claim 1. Cement raw material manufacturing method.   The method for producing a cement raw material according to any one of claims 1 to 5, wherein the cooled steelmaking slag is finely pulverized and then sieved to obtain a cement raw material having a particle size of 45 µm or less.   The cooled steelmaking slag is finely pulverized so that 90 mass% or more of the iron oxide contained in the slag has a particle size of 45 μm or less, and then sieved to use a particle size of 45 μm or less as a cement raw material. The method for producing a cement raw material according to claim 1, wherein:

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