JP2002053910A - Refining agent for molten iron using burnt ash of dust and refining method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a refining agent for molten iron and a refining method using burnt ash of dust with which an expensive flux, such as lime and lime stone, is saved and the problem on the environment of the burnt ash can be solved at the same time by using a burnt ash generated in the case of burning a dust worked into RDF(refuse derived fuel) in an incinerator, for dephosphorization and desulfurization of the molten iron. SOLUTION: The burnt ash generated in the case of burning the dust in the incinerator, is used for refining for removing impurity in the molten iron 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refining agent for molten iron using combustion ash generated when combustible dust generally generated is burned in an incinerator and a method for refining the molten iron.

[0002]

2. Description of the Related Art Conventionally, combustible dust generally generated is solidified.
Fuel, RDF (Refuse Derived F)
uel) and effectively use the dust used as fuel
Being promoted. When this RDF is burned in an incinerator,
Burnt ash forms. Most of this combustion ash contains coagulants, etc.
Add and process into granules, or mix cement etc. to form a lump
After being processed, it is disposed of as waste. Meanwhile, steelmaking
In the industry, phosphorus contained in hot metal smelted in blast furnaces, melting furnaces, etc.
To remove impurities such as (P) and sulfur (S)
Preparatory processing is being performed. This hot metal pretreatment is
(CaO) and limestone (CaCO_Three ), Etc.
To increase the effect of removing S, fluorite (CaF_Two ) Or chloride
Lucium (CaCl _Two ), And auxiliary materials such as iron oxide
The lower main raw material and auxiliary raw material are called flux)
Injecting or injecting pig iron
Or it is added to the hot metal and stirred. But this
Treatment is not necessarily high in reaction efficiency.
P or S concentration in the hot metal of
CaO and CaCO_Three Etc., the use amount increases, and the processing cost
Rises. In addition, the sludge generated during hot metal pretreatment is
The amount of slag has also increased, and slag disposal costs and
There is also a problem with security. As a countermeasure, hot metal pretreatment
Attempts to increase the reaction efficiency and control the amount of slag
Are described in JP-A-57-140808.
As described above, CaO, CaF_Two , Iron oxide, etc.
The so-called pre-cooled, crushed flux after melting the flux
De-P (dephosphorization), De-S (desulfurization) using melt flux
Efficiency and reduce flux usage
Is being done. Also, Japanese Patent Application Laid-Open No. 2-250913 discloses
As described, during the de-P treatment, the basicity (Ca
O / SiO_Two ) Adjusted to 2.5 or less
Mixing 5-20% by weight of manganese oxide to lower the melting point
Reaction between P and lime in hot metal which forms compound and removes P
Calcium silicate (2CaO.Si) that inhibits
O _Two ) A method to suppress the formation of the film and increase the de-P efficiency
is there.

[0003]

However, according to the method described in Japanese Patent Application Laid-Open No. 57-140808,
After melting fluxes such as O, CaF ₂ and iron oxide,
Since the cooled and crushed pre-melt flux is used, equipment for melting treatment is required, and a great deal of cost is required for cooling and crushing. In addition, it is expected that the processing time for de-P and de-S will be shortened and the amount of flux used can be reduced to some extent. However, there is a chemical equilibrium limit to increase the reaction efficiency of de-P and de-S, and the cost is higher. It is difficult to expect the effect.
Furthermore, in the method described in JP-A-2-250913, it is difficult to improve the P removal reaction to a desired level, the amount of expensive fluxes such as CaO and manganese oxide is increased, and the processing cost is reduced. There are problems such as rising and the amount of slag generated. On the other hand, the combustion ash generated when the above-mentioned RDF is burned in an incinerator has very few places to be landfilled or dumped, and is expected to become a major problem in the near future. Research for is being done.

The present invention has been made in view of the above circumstances, and uses combustion ash generated when RDF is burned in an incinerator for de-P and S treatment of hot metal, and uses an expensive flux such as quicklime or limestone. It is an object of the present invention to provide a refining agent and a refining method for hot metal using dust combustion ash that can simultaneously solve the environmental problem of combustion ash.

[0005]

According to the present invention, there is provided a refining agent for hot metal using dust combustion ash according to the present invention, which burns ash generated when dust is burned in an incinerator to remove impurities from the hot metal for refining. Used. As a refining agent for removing impurities from hot metal, combustion ash (RDF ash) generated by burning pre-melt (pre-melted) by burning dust processed into RDF in an incinerator is used. To promote the de-P and S-reactions of the hot metal, and also to make effective use of the combustion ash,
Eliminate environmental problems.

Here, the main component of the combustion ash is Ca
O and 25-77 wt%, a SiO ₂ 12 to 31 wt%,
It is preferred that the al ₂ O ₃ containing 9 to 27 wt%. As a result, since it contains SiO ₂ and Al ₂ O ₃ at a predetermined concentration, it can be quickly dissolved when it comes into contact with hot metal, and can form a slag having a low melting point. More can be promoted. If the amount of CaO contained in the combustion ash is less than 25% by weight, the C
Insufficient aO results in poor P removal. On the other hand, if the content of CaO exceeds 77% by weight, the melting point of the combustion ash becomes high, and the reactivity at the time of contact with hot metal decreases. SiO ₂ contained in combustion ash
If less than 12% by weight, the melting point of the pre-melted combustion ash becomes high, and the reactivity becomes poor. If the SiO ₂ content exceeds 31% by weight, the melting point of the combustion ash decreases, but the effective C
aO is insufficient, and the P removal efficiency is reduced. If the amount of Al ₂ O ₃ contained in the combustion ash is less than 9% by weight, the melting point of the combustion ash increases, and the reactivity when contacting with hot metal decreases.
If l ₂ O ₃ exceeds 27% by weight, the melting point of the combustion ash can be lowered, but the effective CaO is insufficient and the P removal efficiency is reduced.

Further, it is preferable that 5 to 50% by weight of quicklime is mixed with the combustion ash. Combustion ash is further mixed with quick lime and blown into the hot metal to provide effective Ca.
Since an appropriate amount of O can be ensured, it is possible to improve the removal efficiency of P and S and to reduce the total flux. If less than 5% by weight of quick lime (CaO) is added to the combustion ash,
The amount of quicklime that acts on de-P is too small.
The reaction does not improve. On the other hand, if the amount of quicklime (CaO) exceeds 50% by weight, the de-P efficiency is saturated, the unit consumption of quicklime increases, and the processing cost increases.

Further, the method for refining hot metal using dust combustion ash according to the present invention according to the present invention, which is produced when dust is burned in an incinerator, contains 25 to 77% by weight of CaO as a main component,
iO ₂ and 12 to 31 wt%, was added to the combustion ash of the Al ₂ O ₃ containing 9 to 27 wt% in the hot metal is carried out dephosphorization of the solution pig iron, or a desulfurization. By this method, when contacted with hot metal, it is quickly melted to form a slag having a low melting point, promotes the removal of P and S, and effectively removes the combustion ash, which is waste, to remove conventional slag. The same effect as when the S flux is used can be obtained, and environmental problems such as the reclamation of combustion ash can be solved.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the accompanying drawings to provide an understanding of the present invention. The present invention considers that most of the combustion ash (RDF ash) generated after using RDF obtained by processing dust generally generated as a fuel is discarded, and that there is a problem with restrictions on landfill sites and the like, so that it can be effectively used. Was examined. The combustion ash contains C, which is effective for steel refining.
aO, Al ₂ O ₃ , trace amounts of Na ₂ O, etc.
Furthermore, focusing on the fact that it is pre-melted, as a result of intensive research not only to develop inexpensive refining agents but also to contribute to the protection of the social environment, it is effective as a flux for hot metal pretreatment. Thus, the present invention has been achieved. FIG. 1 is an overall view of a hot metal pretreatment apparatus applied to a hot metal refining method using dust combustion ash according to one embodiment of the present invention, and FIG. 2 is a relationship between a time after flux addition and a P removal rate. FIG. 3 is a graph showing the relationship between the time after the addition of the flux and the de-S ratio. As shown in FIG. 1, a hot metal pretreatment device 10 used in a refining method using combustion ash according to one embodiment of the present invention includes a topped car 12 having a tap hole 13 in an upper central portion, and a tapping car 12. The hot metal 11 in the topped car 12 is disposed above the
A lance 15 into which a flux 14 is injected and oxygen is further blown is provided. Reference numeral 16 denotes the flux 14
Is slag that has melted and covered the surface of the hot metal 11.

Next, a refining agent for molten iron using dust combustion ash according to one embodiment of the present invention will be described. Combustion ash (RDF ash) used in the hot metal refining agent of the present embodiment is obtained by crushing raw dust such as residual rice, okara, fish chips, paper, wood chips, waste plastic, resin, and the like. It is ash generated when formed into a size of 2 to 150 mm (RDF) with a commonly used compression molding machine and then burned at a temperature of 600 to 900 ° C. using a combustion furnace. The composition of this combustion ash is as shown in Table 1, and CaO is 25.0 to 7
7.0% by weight, 12.0-31.0% by weight of SiO ₂ ,
The al ₂ O ₃ comprises a 9.0 to 27.0 wt% main component, further, the Na ₂ O from .45 to 7.0 wt%, MgO
1.0 to 5.0% by weight, 0.05 to 2.0% by weight of Cl, and 0.5 to 3.0% by weight of Fe. As other components, FeO, MnO, C, P, S and the like are also contained in a trace amount.

[0011]

[Table 1]

The combustion ash is in the form of fine powder and can be used as it is as a flux for removing P and removing S. However, in order to prevent dust generation during handling and transport, a binder such as water is added to the combustion ash. The granules having a size of 150 mm and dried are used.

Next, in the method for refining molten iron using the combustion ash of dust according to one embodiment of the present invention, the removal and refining of P, which is an example of impurities, that is, the removal of P, is performed by a molten iron pretreatment apparatus 1.
A case in which the process is performed at 0 will be described. P concentration is 0.08-
0.09% by weight, hot metal 1 at 1330-1348 ° C
1 is put into a torpedo car 12, a lance 15 is immersed in the hot metal 11 from a tap hole 13 of the torpedo car 12, and the combustion ash generated from the RDF, which is the flux 14 for removing P, is used alone or further into the combustion ash. 20kg / tonne of hot metal mixed with quick lime of 5-50% by weight
Conveyed by oxygen gas of 6 kg / cm ² , lance 15
Was blown into the hot metal 11 from the tip. The flux 14 is dispersed as a turbulent flow in the hot metal 11 together with the carrier gas composed of the injected oxygen gas as shown by arrows in FIG.
₂ O ₅ ) reacts with CaO in the flux 14 to form 3Ca
By generating the slag 16 containing O.P ₂ O ₅ , the hot metal 11 is de-Ped.

Further, the oxygen gas supplied from the lance 15 was replaced with nitrogen gas, and the other conditions were made the same as the P removal treatment, and the S removal treatment of the hot metal 11 was performed. As a result, the effect of capturing S in the hot metal 11 by CaO in the combustion ash and the mixed quicklime was improved, and the hot metal 11 could be sufficiently removed from the S.

FIG. 2 shows the experimental results of the P and S characteristics of the combustion ash.
Was used as the flux (indicated by a circle in the figure), whereas when the entire amount was made into combustion ash (RDF ash) (indicated by a circle in the figure),
The rise of P removal immediately after the addition of the flux is also good, and the removal rate of P is improved with the elongation of the time, and an effect that is almost the same is obtained. Furthermore, 5% by weight of CaO is added to the combustion ash.
When mixed (■ in the figure) or when 50% by weight of CaO was mixed with the combustion ash (印 in the figure), the P removal rate was higher than that of the combustion ash alone, and it was effective as a P removal agent. You can see that. In the figure, a triangle indicates 10% by weight of fluorite (C
This is a reference example when aF ₂ ) is added. FIG. 3 shows a case where the removal rate of S was compared in the same manner, and CaO conventionally used was used as a flux (indicated by a circle in the figure).
In contrast, in the case where the entire amount was made into combustion ash (indicated by ● in the figure), the S removal ratio was significantly improved. Furthermore, CaO is added to the combustion ash.
5% by weight (indicated by ■ in the figure) and 50% by weight in combustion ash (indicated by ▲ in the figure), a superior de-S rate was obtained in each case than when combustion ash was used alone. , Effective as a de-S agent.

[0016]

Next, an embodiment of a method for refining molten iron using dust combustion ash according to the present invention will be described. Phosphorus (P) concentration is 0.082 to 0.087% by weight, and sulfur (S) concentration is 0.08% by weight.
029-0.031% by weight of hot metal is put in a tope car, a lance is immersed in the hot metal, and a refining agent (flux)
Ash alone or 5 to 50% by weight of ash
20kg / tonne of hot metal using a mixture of quicklime
And carried by the oxygen gas ~6kg / cm ^2, when subjected to de-P treatment blown into the hot metal from the lance tip portion (Example 1-3), changing the oxygen gas to nitrogen gas, de-S process Each case was performed (Examples 4 to 6). The P concentration (% by weight) and the S concentration (% by weight) before and after the treatment, the quality of the treatment cost, and the overall evaluation were examined.
Table 2 shows the results. Example 1 is a case in which P was removed using a mixture of CaO and 5% by weight of combustion ash,
The P removal efficiency was good, the processing cost was low (低 く), and a good overall evaluation (○) was obtained. Example 2 shows a case where de-P was performed using a mixture of CaO and 50% by weight of combustion ash. The de-P was excellent, the processing cost was low (○), and the overall evaluation was excellent (◎). Obtained. Example 3 is a case where de-P is performed using only combustion ash,
The P removal efficiency was good, the processing cost was low (低 く), and a good overall evaluation (○) was obtained. Example 4 is a case in which the removal of sulfur was performed using a mixture of CaO and 5% by weight of the combustion ash. The removal efficiency was good, the processing cost was low (（), and the overall evaluation was good (○). was gotten. Example 5 is a case in which S was removed using a mixture of CaO and 50% by weight of combustion ash. The removal efficiency was excellent, the processing cost was low (コ ス ト), and the overall evaluation was excellent (◎). Obtained. In Example 6, the removal of sulfur was performed using only the combustion ash, the removal efficiency was good, the processing cost was low (低 く), and a good overall evaluation (○) was obtained.

[0017]

[Table 2]

On the other hand, in Conventional Example 1, the de-P treatment was performed using only CaO, and the de-P efficiency was poor.
The processing cost was also high, and the overall evaluation was poor (x). In Conventional Example 2, 10% by weight of CaF ₂ was added to CaO.
And the removal of P was performed, and the removal of P was improved, but the processing cost was increased and the overall evaluation was somewhat poor (△).

The embodiments of the present invention have been described above.
The present invention is not limited to the above-described embodiment, and all changes in conditions that do not depart from the gist are within the scope of the present invention. For example, in addition to using the combustion ash as a flux for removing P and S from molten iron, it can be used as a substitute for CaO for refining molten steel or as a flux for secondary refining such as ladle refining. Further, at the time of the de-P treatment using the combustion ash, the oxygen blown from the lance may be used as iron oxide, or a mixture of oxygen and iron oxide may be used.

[0020]

The refining agent for molten iron using dust combustion ash according to any one of claims 1 to 3 uses the combustion ash generated when the dust is burned in an incinerator for removing impurities from the molten iron for refining. When combusted in combustion, the pre-melted combustion ash can be effectively used as a de-P and S-removing agent for hot metal to save expensive fluxes such as quicklime and limestone, and simultaneously reduce the environmental problems of combustion ash. Can be solved.

In particular, the refining agent for hot metal using dust combustion ash according to claim 2 contains 25% CaO as a main component of the combustion ash.
To 77 wt%, a SiO ₂ 12 to 31 wt%, Al ₂ O
₃ to 9 to 27% by weight, so that the dissolution is good,
A slag having a low melting point can be formed to further promote the removal of P and S.

The refining agent for hot metal using the combustion ash of dust according to the third aspect of the present invention mixes the combustion ash with 5 to 50% by weight of quicklime in an internal part. The removal efficiency of P and S can be more stably improved.

The refining method of molten iron using the combustion ash dust according to claim 4 is generated upon burning the dust incinerators, 25-77 wt% of CaO as a main component, a SiO ₂ 12 to 31
By adding to the hot metal, combustion ash containing ₉ to 27% by weight of Al ₂ O ₃ is added to the hot metal to dephosphorize or desulfurize the hot metal. To stably promote the de-P and de-S reactions and effectively utilize the waste ash to obtain the same effect as when using the conventional flux for de-P and de-S. In addition, environmental problems such as the reclamation of combustion ash can be solved.

[Brief description of the drawings]

FIG. 1 is an overall view of a hot metal pretreatment device applied to a hot metal refining method using dust combustion ash according to one embodiment of the present invention.

FIG. 2 is a graph showing the relationship between the time after addition of flux and the P removal ratio.

FIG. 3 is a graph showing the relationship between the time after the addition of flux and the S removal rate.

[Explanation of symbols]

10: Hot metal pretreatment device, 11: Hot metal, 12: Topped car, 13: Tap hole, 14: Flux, 15: Lance, 16: Slag

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Ryoichi Sakomura 1-1-1, Hibata-cho, Tobata-ku, Kitakyushu-shi, Fukuoka Prefecture Inside Nippon Steel Corporation Yawata Works (72) Inventor Kazuo Wakabayashi Kamifusa-gun Kita, Okayama Prefecture 2252 Nakayama Lime Industry Co., Ltd. (72) Inventor Mitsuru Ueda 2-1 Yamadaoka, Suita-shi, Osaka F-term (reference) 4D004 AA36 BA10 CA15 CA50 CB47 CC11 DA03 DA10 4K014 AA02 AA03 AB02 AB03 AB04 AC03 AC08 AC14 AC16 AD01 AD27

Claims (4)

[Claims] 1. A refining agent for hot metal using dust combustion ash, wherein combustion ash generated when the dust is burned in an incinerator is used for refining and removing impurities from the hot metal. 2. The refining agent for hot metal using dust combustion ash according to claim 1, wherein CaO is used as a main component of the combustion ash.
The 25-77 wt%, a SiO ₂ 12 to 31 wt%, A
refining agent of molten iron with combustion ash dust, characterized in that it contains l ₂ O ₃ 9 to 27 wt%. 3. The refining agent for hot metal using dust combustion ash according to claim 1 or 2, wherein the combustion ash has an internal content of 5 to 50 parts.
A refining agent for hot metal using dust combustion ash, characterized by mixing with quick weight of quick lime. 4. It is produced when dust is burned in an incinerator and contains 25 to 77% by weight of CaO and 12% of SiO ₂ as main components.
To 31 wt%, it was added to the combustion ash of the Al ₂ O ₃ containing 9 to 27 wt% in the hot metal, the solution pig iron dephosphorization, or hot metal using the combustion ash dust and performing desulfurization Refining method.