JP3035285B1 - Method for producing carburized material for steel making containing electric furnace dust, carburized material for steel making obtained thereby and method for recycling electric furnace dust - Google Patents

Abstract

[PROBLEMS] To effectively utilize electric furnace dust as a new carburizing material for steel making, reduce the amount of treatment, and develop a technology for inexpensively recovering valuable metals such as iron and zinc contained therein. . SOLUTION: Electric furnace dust 30 to 80 wt. % And CD
Q powder and other carbonaceous material powders 20 to 70 wt. %, A binder such as PDA is added, mixed, heated, dehydrated, and molded to produce a carbonized material for steelmaking. Carburized wood contains at least all carbon:
20-65 wt. %, Zinc oxide: 8 to 23 wt. Include%. The carburized material is used in the electric furnace to recycle electric furnace dust. [Effect] The electric furnace reduces slag of dust and reduces the carry-out amount, improves iron yield and lowers costs, and reduces the load on the crude zinc recovery plant, contributing to the improvement of the global environment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for improving the method of treating dust generated in an electric furnace steelmaking plant, thereby reducing the amount of treatment and advantageously recovering valuable metals contained in the dust. In particular, increase the zinc concentration in the dust containing recovered zinc oxide, and effectively utilize the dust as a carburizing material for steelmaking in electric steelmaking furnaces and other steelmaking furnaces that melt and refine steel scrap and pig iron as raw materials. It is about technology.

[0002]

2. Description of the Related Art In electric furnace refining for steelmaking, usually, O ₂ gas is supplied from a lance into molten iron in a furnace while dissolving iron swarf and a slag-making agent as a main raw material, and a carbon material such as coke powder. Into metal and slag. C in the injected carbon material has the following effect.

[0003] The addition of heat to the charge, molten metal and molten slag by combustion into CO gas and CO ₂ gas,
Rapid dissolution is achieved in combination with the use of large amounts of O ₂ gas. Therefore, it also partially replaces the power energy. In this case, a large amount of FeO is generated and enters the slag.

[0004] It acts as a reducing agent for various oxides such as iron oxide, manganese oxide and zinc oxide in molten slag and ash formed on the surface of molten iron.

[0005] Carburizing action in the molten iron.

Conventionally, carbon materials used in electric furnaces include:
Small lump coke, coke powder, CDQ powder (coke fire extinguishing equipment collection powder), briquette of CDQ powder, and iron powder-containing CD
There are briquettes of Q powder. These are oxide reduction,
The reaction contribution rate of various reactions such as combustion to CO gas or CO ₂ gas and carburization to molten steel is high, and can be manufactured with relatively simple equipment. Therefore, it is still widely used today.

On the other hand, in an electric furnace steelmaking plant, so-called electric furnace dust collected by a dust collector is generated. The amount is about
It is as large as about 15 to 23 kg per ton of crude steel production. About 40% of the electric furnace dust is disposed of by landfill. However, electric furnace dust contains valuable metals such as Zn and Fe, and Zn is recovered and processed in the form of zinc oxide to become a raw material for a crude zinc oxide which is a raw material for zinc refining. A common source of electric furnace dust is dust generated from an electric furnace, but is roughly classified into dust directly collected and dust collected in a building by a dust collecting facility for collection. Direct dust is
It is dust contained in the exhaust gas sucked through the exhaust gas hole in the upper part of the electric furnace. Choku引dust is charge to the electric furnace steel scrap and lime and dust generated from the secondary raw material dolomite, dust generated oxidized by O ₂ gas blowing used in melting and refining process, and It consists of heavy oil and kerosene combustion residues used for heating. Tables 1 and 2 show examples of industrial analysis and chemical analysis of direct dust.

[0008]

[Table 1]

[0009]

[Table 2]

The ash content of the directly drawn dust is about 85 wt. % Or more, volatile matter + fixed carbon is 3 to 12 wt. %include. Also, as can be seen from Table 2, Fe, Zn and Pb
Etc. are contained in a large amount, and Zn is 15 to 22 wt. % And many. This is due to the recent demand for steel,
In particular, the amount of galvanized steel sheet used has increased, and the proportion of the scrap in steel scrap has increased. Thus, in a steelmaking electric furnace using iron scrap as a main raw material, a large amount of zinc was contained in the electric furnace dust.

The dust collected from the building includes dust contained in gas leaked from the electric furnace, various kinds of dust generated in the electric furnace steelmaking plant, for example, rust attached to purchased iron scrap, fine powder of earth and sand, and the like. Dust floating in the factory, such as lime particles and coke particles, is captured. Therefore,
The composition of the dust collected in the building varies depending on the type of suspended dust in the building where the dust is collected. Table 3 shows an example of chemical analysis of dust collected from a building of an electric furnace.

[0012]

[Table 3]

The building dust contains the heavy metal elements Fe, Zn and Pb as well as the direct dust, and also contains carbon.

On the other hand, landfill disposal of electric furnace dust requires a large disposal cost. Therefore, research and development of a treatment method for effectively utilizing valuable metals in electric furnace dust have been carried out, and the following techniques are available for recovering Zn.

[0015] As the zinc recovery process currently being carried out, for example, the Welz method and the semi-blast furnace method are known.
All of these have a zinc content of about 50 wt. % Is a process for producing crude zinc oxide in which the percentage is maintained. That is, a carbon material or other reducing agent is supplied to the electric furnace dust to reduce zinc oxide. That is, in the case of the Welz method, a mixture of an electric furnace dust and a carbon material is heated in a rotary kiln and subjected to a reduction treatment to evaporate zinc. In the case of the semi-blast furnace method, electric furnace dust, carbonaceous material, slag-making material and the like are formed and supplied to the semi-blast furnace to melt and evaporate zinc. Thus, in each case, the zinc oxide powder that has been air-oxidized outside the furnace, that is, the crude zinc oxide is recovered (hereinafter referred to as “prior art 1”).

In each of the above processes, large-scale equipment such as a rotary kiln and a semi-smelting furnace is used, and direct production of crude zinc oxide is performed as a method of effectively utilizing electric furnace dust.

On the other hand, in order to use electric furnace dust as a raw material for producing the above crude zinc oxide, a process for concentrating the Zn content in the electric furnace dust has been proposed. This is a method in which molten iron or hot metal is held in a melting furnace or a reaction furnace as a dedicated zinc oxide concentrating apparatus, and this is mainly used as a heat source for reducing zinc oxide. For example,
As shown in JP-A-9-279265,
Dust is added to the furnace together with a carbon material as a reducing material and slag-making material, and an oxygen-containing gas is supplied thereto. At that time, in order to prevent dust from blowing up and scattering, an oxygen-containing gas is blown from a tuyere provided horizontally below the slag surface level on the side of the furnace body. A method of collecting dust containing zinc oxide particles in which zinc reduced and evaporated at a high temperature is oxidized outside a furnace is disclosed (hereinafter, referred to as “prior art 2”). Also, JP-A-9-268332 (hereinafter referred to as “prior art 3”) and JP-A-9-241
No. 718, hereinafter referred to as “prior art 4”), the dust and the carbon material are blended, a binder is added to form a briquette, and the briquette is put into molten iron previously stored in a furnace. This shows a method of recovering dust containing zinc oxide particles, in which zinc reduced and evaporated at a high temperature is oxidized outside the furnace, similarly to the prior art 2. Moreover, in the prior arts 2 and 3, the zinc content that can be supplied as crude zinc oxide from the zinc oxide particles in the collected dust is about 50 wt. % Of the particles must be separated. Here, when the zinc content is 50 wt. % Or more of zinc oxide particles are distributed on the fine particle side of, for example, 10 μm or less, so that the dust is classified with a predetermined particle size as a boundary in order to facilitate handling of the dust collected in the subsequent processing steps. For that purpose, dust collecting devices are provided in two stages in series to classify and collect dust. Then, the processing described above is repeated again for dust having a large particle diameter collected in the first stage. According to Prior Art 2, the ratio of this recirculation treatment is about 30 wt. %.

As described above, in the prior arts 2 to 4, molten metal such as molten iron or hot metal is separately prepared in advance, and the molten metal is used as a heat source to cause a reduction reaction of zinc oxide and iron oxide in the dust. This constitutes a concentration treatment step. In this way, it is necessary to provide a dedicated furnace for melting and holding the molten metal and its accompanying equipment. That is, a lot of equipment costs and operation costs are newly added.

[0019]

The above-described conventional method for treating electric furnace dust has the following problems. First, Zn for utilizing Zn content in electric furnace dust as an effective resource
The fraction enrichment technique has the following problems.

(1) In all of the above-mentioned electric furnace dust resource utilization technologies, the Zn content in the dust is reduced to 50 wt. It is an object of the present invention to directly concentrate to not less than% and to produce crude zinc oxide as a raw material for zinc smelting. In the prior art 1 such as the Weltz method, it is processed in a rotary kiln of a specialized factory. The prior arts 2 to 4 require a dedicated melting furnace or reaction furnace for accommodating molten iron or hot metal for that purpose, and additionally provide a large-scale recovery facility, for example, a plurality of dust collectors for classification of dust particle size. Therefore, equipment costs and operation costs become enormous. Further, even when the dust processing according to the prior arts 1 to 4 is entrusted, the processing cost and the transportation cost are large. Under such circumstances, many electric furnace dusts have been disposed of by landfill as described above in accordance with laws and regulations. Therefore, development of a technology for recovering and treating valuable metals such as zinc and iron at low cost from electric furnace dust is desired.

[0021] (2) In addition, an oxide of valuable metals in an electric arc furnace dust to a reducing and recovery, as containing substance form of the electric furnace dust, and molded into briquettes by adding a binder to the electric furnace dust PLAIN Or granulated pellets . In this case, since the reduced material such as coke powder is contained only in a small amount in the molded product, the reducing material for zinc oxide and iron oxide in the dust is separately supplied from outside the system of the molded or granulated material. There is a need. In this case, even if the reducing agent is supplied, the dust is fine particles and easily scatters, so that a sufficiently large contact reaction area with the reducing agent cannot be secured. Also, mix coke powder as a reducing agent in electric furnace dust,
There is also disclosed one molded by adding a binder.
In this case, when charged into an electric furnace, if the coke ratio in the molded product is relatively small, the strength of the molded product is small,
Therefore, when the electric furnace is put into an electric furnace, it is pulverized and scattered, and the ratio of the electric furnace dust to the molten slag in the furnace is reduced. as a result,
The reduction and recovery yield of iron decreases, and the rate of concentration of Zn concentration in dust collected by reoxidation of the atmosphere after reduction and evaporation of zinc oxide decreases, which does not contribute to the purpose of recovering Zn.
Therefore, reprocessing of the electric furnace dust is required, and the cost is increased.

Next, there are the following problems in handling and disposing of electric furnace dust.

(3) As described above, in the treatment of electric furnace dust, conventionally, nearly half of the electric dust has been landfilled and disposed of after the pollution-free treatment. However, this decontamination disposal is very costly, and its cost reduction is an urgently important issue. However, such an inexpensive technology has not been developed.

(4) On the other hand, electric furnace dust has a problem that it is extremely difficult to handle in handling because of its fine particle size. The particles of the electric furnace dust are easy to generate because they are fine particles, and are scattered to pollute the surroundings, easily absorb moisture, and when muddy, it is difficult to remove moisture, so that handling is troublesome. Therefore, storage and transportation are also expensive.

Therefore, the present inventors have made an object of the present invention to develop a technique for solving all of the above problems. That is, (a) expensive equipment such as a melting furnace or a reaction furnace, a dust collector for fine powder particle size classification and its accompanying equipment is not required, and there is no need to prepare molten metal in advance, and both equipment and operation costs are reduced. Invented a total process of electric furnace dust treatment and utilization by utilizing inexpensive existing facilities, thereby developing a revolutionary treatment method for electric furnace dust, and (b) electric furnaces that are fine powder particles. Change the dust into a form that is easy to handle, and reduce the volume to reduce transportation costs. (C) In addition, as a method of using electric furnace dust,
Simply concentrate and recover valuable metals contained in electric furnace dust,
In addition to saving metal resources such as Zn and Fe, in the total process (a), electric furnace dust is also used as a raw material for producing carburized steel for steelmaking, thereby reducing the manufacturing cost in the electric furnace steelmaking process. The aim was to develop a new carburizing material for steelmaking in electric furnace steelmaking that could also contribute to steelmaking.

[0026]

Means for Solving the Problems The present inventors have studied the problem solving from the above viewpoint. As a result, as an electric furnace dust treatment / utilization technology, we studied and experimented on the applicable product and the electric furnace dust recycling process including its manufacturing process. The following [1] and [2]
The following two items were examined and basic tests and investigations were conducted.

[1] Targets of Electric Furnace Dust Utilization As a technology for utilizing electric furnace dust as a resource, it was considered desirable to develop a new carburizing material for steelmaking in electric furnace steelmaking. The study process leading to this focus is as follows.

[1] -1. Examination of products to which electric furnace dust is applied First, since electric furnace dust is fine particles, it is scattered by the rising air current in the furnace at the time of charging into the electric furnace and after the charging, and the yield of charging the electric furnace dust Therefore, it is necessary to take measures to suppress this. Further, in order to reduce zinc oxide and iron oxide contained in the electric furnace dust with the carbonaceous material, it is desirable to increase the contact area ratio between the electric furnace dust and the carbonaceous material as much as possible. On the other hand, it is desirable that the specific surface area be large in accordance with the electric furnace dust side condition as the carbon material side condition.
Q powder is suitable. As described above, by avoiding a decrease in the charging yield, increasing the reaction interface area between the reactants and stabilizing the reaction interface, the reduction reaction rate of zinc oxide and iron oxide in the electric furnace dust is increased, and the reaction rate is increased. In order to achieve the reduction rate, it is desirable that the electric furnace dust and the powdery and granular carbon material are well mixed, formed into an appropriate size, and charged into the electric furnace. Since coke breeze and CDQ powder were inexpensive and the supply was stable, it was considered that they were suitable as a granular carbon material in terms of supply and demand of raw materials and cost.

On the other hand, in a conventional electric furnace steelmaking process using scrap iron (steel scrap) as a main raw material, a carbon-containing substance is supplied into a furnace through a melting period, an oxidation refining period, and a reduction refining period. The supply of the carbon-containing substance is to reduce the oxides of metals such as Fe and Mn in the molten slag in the melting period and each refining period, and to adjust the C content of the molten steel at the end point of the oxidizing refining to the target value. It is done for the purpose. This C
The feed rate is about 2 in a normal electric furnace steelmaking operation.
The amount is as much as about 0 kg / t-steel. Also, the supply form of the carbon-containing substance is usually briquette
So-called carburizing material, which is a carbon-containing material molded into pellets or granulated into pellets, blowing a particulate carbon-containing material such as coke breeze with a carrier gas, exhausting the arc electrode and melting molten steel. C is supplied accompanying the addition of ferroalloys for adjusting the composition of C. Of the C-containing substances, the types of the carburized materials and the properties thereof generally differ depending on each electric furnace steelmaking plant. Then, the appropriate supply amount of the carburized material is determined based on the raw materials used in the operation,
It differs depending on the type of slag-making agent, O2 gas and fuel and their mixing ratio, as well as the type of smelting steel and the target component composition. In view of this situation regarding the supply of carburized material in the electric furnace steelmaking operation, in the present invention, not only the operation using the carburized material of the present invention alone, but also the combined use of the above-described wide range of properties with the carburized material It was considered important to produce a carburized material that was also possible. The company also decided to reduce the production cost by using as inexpensive by-products as possible for the procurement of raw materials for carburizing materials.

In consideration of the above study, the following basic experiments were conducted to develop a technique for manufacturing a carburized material for steelmaking in electric furnace steelmaking using electric furnace dust and powdered granular carbon as main raw materials, and the present invention was carried out. I got a lot of knowledge.

[1] -2. Basic experiments and knowledge obtained from them (a) Basic experiments for reduction of carburized material for steelmaking Electric furnace dust generated during normal electric furnace steelmaking operation and CDQ powder generated during normal blast furnace coke oven operation (coke extinguishing equipment ) And a proper amount of a binder, mixed well, heated, and dewatered, and molded the resulting granular semi-finished product into briquettes of a predetermined size , or Pellets were granulated, and two types of carburized materials for steelmaking were manufactured by test. And the reduction experiment of the metal oxide contained in a carburizing material was performed. Table 4 shows the component compositions of the electric furnace dust and CDQ powder used in the production of the carburized material.

[0032]

[Table 4]

One of the two types of carburized materials N
o. BCA-40 is electric furnace dust: 40 wt. % And C
DQ powder: 60 wt. % As a binder, and PDA (propane di asphalting asphalt) as a binder in an amount of 6 wt. %, A weight of about 35 g, a volume of about 18.2 cc / piece, and a porosity of about 11
It was molded to the percent of the briquette. The other carburized material No. PC
B-85 is electric furnace dust: 85 wt. % And CDQ powder:
15 wt. % Of water, and water as a binder. %, About 0.8 g of individual weight,
The pellet was granulated into a pellet having a volume of about 0.4 cc / piece and a porosity of about 27%.

The conditions for the reduction experiment were set so as to approximate the use of a carburized material in an electric furnace steelmaking operation. That is, the sample was charged into an N ₂ gas atmosphere resistance heating furnace in which the temperature in the furnace was maintained at 1000 ° C., and while keeping the input power at the power at the time of charging the sample, the zinc oxide and the zinc oxide in the carburized material were kept for 30 minutes. A reaction for reducing metal oxides such as iron oxide with carbon in CDQ powder was performed. Then, the inside of the furnace is blown with N ₂ gas and Z
The ZnO fine particles generated by the reoxidation of the metal Zn vapor generated by the reduction and evaporation of nO were prevented from falling and accumulating on the residual sample surface. During the experiment, carburized wood No. BCA-4
In the early stage of the experiment of No. 0, black smoke considered to be a part of the decomposition product of the binder PDA was blown out, and the atmosphere became a strong reducing atmosphere. PCB-85
It was not recognized in.

The appearance of the remaining carburized material samples after the experiment was significantly porous compared to the appearance before the experiment due to the effect of the reduction reaction of the metal oxide in the carburized material. I was However, only a small amount of powdery or granular material that appeared to be pulverized or scattered by the heat shock during the reduction reaction was found around the residual sample.

The weight of the carburized material No. BCA-
No. 40 is 35.33 g for one briquette, carburized material No. 40.
PCB-85 is 36.00 g for 43 pellets. After completion of the reduction reaction experiment, the sample was taken out of the furnace and rapidly cooled to room temperature in water and dried by ventilation with Ar gas. The above-mentioned experimental conditions are the same as those of the above-mentioned No. 1 after the first steel scrap and the slag-making material were charged into the furnace in a normal electric furnace steelmaking operation. It is set for the purpose of estimating the reaction behavior of these carburized materials, assuming a case where the carburized materials are charged. That is, it should be noted here that, similarly to the carburizing material supply timing in the ordinary electric furnace operation, the carburizing material supply timing planned in the present invention is the initial charging time and the charging time after the electric furnace is energized. In general, the material is usually divided into two or three portions and charged at the time of heating and melting of the material, and thus it is desirable to determine the supply time of the carburized material of the present invention. The reason for this is that briquettes and other shaped carburized materials are pulverized by remarkably intense boiling due to the rapid contact of molten slag and molten metal with the high-temperature molten metal, and are scattered, reducing the use of electric furnace dust in carburized materials This is to prevent that. Table 5 shows the carburized material N
o. BCA-40 and no. The component composition of PCB-85 is shown.

[0037]

[Table 5]

For the carburized material sample remaining after the reduction experiment, the residual weight was measured, the component composition was analyzed, and the apparent specific gravity and the porosity were measured, and were compared with the measured values before the reduction experiment. Table 6 shows changes in the sample weight and the component composition before and after the reduction, and Table 7 shows the weights (piece weights) of the samples before and after the reduction experiment.
4 shows changes in apparent specific gravity and porosity. Table 7 shows comparison data of the solid volume contact ratio of dust and CDQ powder inside both samples.

[0039]

[Table 6]

[0040]

[Table 7]

(B) Discussion and knowledge of the experimental results According to the experimental results, the sample weights were all reduced to about two-thirds. If so, scattering and disappearance of the sample during the reduction are considered to be small. It is verified from the experimental results that the amount of scattering and disappearance is small. Total Fe weight in sample, and CaO + S
Table 8 summarizes the weight loss before and after the reduction experiment by regarding the weight of iO ₂ + Al ₂ O ₃ + MgO (referred to as ΔSL) as a tracer. In any of the samples of the carburized materials No. BCA-40 and PCB-85, the reduction amount is 4 to 5% of the initial sample weight when estimated for all Fe, and 6 to 7 of the initial sample weight when estimated for ΔSL. Therefore, in this study, the amount of scattering and disappearance of the sample during the reduction experiment was ignored.

[0042]

[Table 8]

Looking at the weight behavior of the iron oxide in the sample before and after the reduction experiment, both Fe ₂ O ₃ and FeO after the reduction experiment were 0%.
g, and the Fe-oxide is substantially reduced to 100%. On the other hand, when looking at the weight behavior of zinc oxide, a considerable amount remains even after the reduction experiment. Using the experimental data in Table 6, the reduction ratio of ZnO: R (ZnO) was calculated by the formula: R
(ZnO) = (ΔZnO / ZnO (initial)) × 10
0 (however, ΔZnO: reduced weight of ZnO, Z
nO (initial): weight of ZnO before reduction).

The reduction ratio of ZnO is as follows: For sample BCA-40: 73.3% For sample PCB-85: 38.9%

Next, the above experimental results were thermodynamically considered to estimate the amount of C required for reduction. Meanwhile, carburized materials having various mixing ratios of raw materials were separately manufactured by test and used in the electric furnace steelmaking operation. Then, by considering the results, the knowledge for determining a desirable mixing ratio of the electric furnace dust and the carbonaceous material powder, which are the raw materials of the carburized material to be manufactured in the present invention, was obtained. The progress will be described below.

Reduction Reaction of Fe Oxide and Zn Oxide with Carbon: The amount of C required for reduction of Fe oxide and Zn oxide in the reduction experiment was estimated using the experimental results.

The carbon C of Fe ₂ O ₃ , Fe ₃ O ₄ and FeO
(S) by a reduction reaction formula is the following when the iron oxide is generated is reduced CO (a-1) ~ ( a-3) type, as well as the following when the CO ₂ is produced (b-1) ~ (B-3) The reason why the reduction reaction by C (s) is considered in this way is that it is a reduction experiment of a system in which a large amount of carbon C (s) coexists. That is, the reaction when CO is generated is as follows: 3Fe ₂ O ₃ (s) + C (s) = 2Fe ₃ O ₄ (s) + CO (g) ΔG = 32920−54.75 T (a-1) Fe ₃ O ₄ (s) + C (s) = 3FeO (s) + CO (g) ΔG = 47920−50.85T (a-2) FeO (s) + C (s) = Fe (s) + CO (g) ΔG = 35350−35.90T (a-3), and the following equation (A) is derived from the above equations (a-1) to (a-3).

Fe ₂ O ₃ (s) + 3C (s) = 2Fe (s) + 3CO (g) ΔG = 113620-123.89T (A) Accordingly, Fe ₂ O ₃ (s) in the carbonized material is This is the case where CO is generated by reduction with carbon (s), and is summarized by the formula (A).

On the other hand, when the iron oxide is reduced by carbon C (s) to produce CO ₂ , the reaction is as follows: 6Fe ₂ O ₃ (s) + C (s) = 4Fe ₃ O ₄ (s) + CO ₂ ( g) ΔG = 25040−67.44T (b-1) 2Fe ₃ O ₄ (s) + C (s) = 6FeO (s) + CO ₂ (g) ΔG = 55040−60.00T (b-2) 2FeO (s) + C (s) = 2Fe (s) + CO ₂ (g) ΔG = 29900-30.1T (b-3), and from the above equations (b-1) to (b-3) The following (B)
An equation is derived.

2Fe ₂ O ₃ (s) + 3C (s) = 4Fe (s) + 3CO ₂ (g) ΔG = 104840−122.68T (B) Accordingly, Fe ₂ O ₃ (s) in the carburizing material Is reduced by carbon C (s) to produce CO ₂ , wherein (B)
It is summarized in the formula.

From the above, at the experimental temperature of 1000 ° C., Fe ₂ O ₃ in the sample exists in an atmosphere having a reduction potential that can be sufficiently reduced by the carbonaceous material powder in the sample.
Next, the chemical equivalent of C required for the reduction of Fe ₂ O ₃ is
When considering which one of the equations (A) and (B) is to be followed, it may be considered that the equation (A) is substantially followed for the following reason. That is, the reduction reaction of FeO in the carburized material by C is represented by the following formula (a-3): FeO (s) + C (s) = Fe
(S) + CO (g) or 2FeO of the formula (b-3)
It is considered that this is performed by any of (s) + C (s) = 2Fe (s) + CO ₂ (g).

On the other hand, in consideration of the fact that the boiling point of Zn is 906 ° C., the reduction reaction of ZnO in the carburized material with carbon C (s) is as follows, considering the initial setting temperature of this experiment: 1000 ° C. It is presumed that the equation (C) follows.

ZnO (s) + C (s) = Zn (g) + CO (g) ΔG = 88720 + 10.35TlogT−103.33T (C)

In order to prove the above assumption, Fe ₂ O ₃ and FeO, which are the components of Fe oxide, and ZnO, which is the component of Zn oxide, obtained by the analysis of the carburized material sample before and after the reduction experiment. Using the composition analysis values, the reduction rates of Fe ₂ O ₃ , FeO, and ZnO in the electric furnace dust contained in the carbonized material were calculated as follows. As mentioned above, the scattering and disappearance of the sample during the experiment is so small that it can be ignored.
The mass balance of carbon before and after the reduction experiment was considered. That is, the calculated weight P (g) of the sum of the C equivalents required to reduce the reduced amount of Fe ₂ O ₃ , FeO, and ZnO in the sample before and after the reduction experiment, and the measured reduced weight Q ( Comparison with g) is as shown in Table 9.

[0055]

[Table 9]

For the sample PCB-85, the measured weight Q
Is close to the calculated weight P, the difference QP is 0.118 g,
(Q−P) /Q=4.2%, which is small. Therefore, the measured weight Q of the oxide is close to the calculated weight P, so that the Fe
It can be considered that most of the reduced amounts of ₂ O ₃ , FeO and ZnO are reduced by C.

On the other hand, for sample BCA-40, PDA (decomposition temperature: 24
0 ° C) was added, and according to observations during the experiment, hydrocarbon gas, CO, soot, and hydrogen generated by the decomposition of PDA were generated because black smoke erupted at the beginning of the experiment. it is conceivable that. The weight of C contained in PDA is 1.7
Since the difference between the calculated value and the actually measured value is calculated taking this into account, the difference is 0.171 g, which is (Q−
P) /Q=5.1%. Thus, PDA
Is treated as described above, the measured weight Q of the oxide is close to the calculated weight P also in the case of the sample BCA-40.
It can be considered that most of the reduced amounts of ₂ O ₃ , FeO and ZnO are reduced by C.

In consideration of the above, in both the carburized wood samples BCA-40 and PCB-85, Fe ₂ O ₃ and FeO did not remain in the reduced sample, and the total weight of the Fe component was metal. Considering that it is in the form of Fe, the total amount of both Fe ₂ O ₃ and FeO in each of the carburized wood samples BCA-40 and PCB-85 is Fe ₂ O ₃ (s ) + 3C (s) = 2Fe (s) +3
CO (g) and FeO (s) + C (s) = Fe
(S) + CO (g), and the total weight of the reduced ZnO is reduced by the reaction formula ZnO (s) + C (s).
= Zn (g) + CO (g).

As described above, as a result of examination according to the mass balance of C before and after reduction, it is considered that the reduction reaction of each oxide proceeds according to (a-1) to (a-3) and (C). I found it good.

As described above, the reduction rate of Fe oxide in the carburized material in the reduction experiment was 100%, but the reduction rate of Zn oxide was as described above in the case of sample BCA-40:
73.3%, in the case of sample PCB-85: 38.9%. On the other hand, according to a separate actual operation site test conducted by the present inventors, in the actual operation of electric furnace steelmaking, most of the Zn component mixed into the electric furnace system from steel scrap in the past was mostly contained in electric furnace dust. And it was found that only a small proportion entered the electric furnace slag. That is, when the Zn content transferred to and remaining in the slag was calculated from the analysis results of the molten slag samples in the electric furnace oxidation refining period and the reduction refining period, the amount of the input Zn charged into the electric furnace was 0.3 wt. %. Therefore, even when the shaped carburized material prepared by blending the electric furnace dust and the carbon material powder planned in the present invention is charged from the charging time of the electric furnace operation to the initial melting, Zn inside
It is estimated that the proportion of oxides that would be contained in the molten slag after the refining was very small. However,
The present inventors have ensured that the reduction rate of Zn oxide ZnO (s) in dust with carbon C (s) is about 50% or more by the evaluation method according to the method of the present reduction experiment. It was predicted that the heat using the carburizing material planned in the invention can be operated stably in the same manner as the conventional operation heat. In consideration of the steelmaking required time in the actual operation test, the operation results such as the power consumption unit, and the furnace operability such as the occurrence of energization interruption when the carburized material is charged at the time of charging the raw material and during the melting period, The prediction was found to be valid. The results of the actual operation test will be described in the section of Examples.

Therefore, in a reduction experiment of oxides contained in the electric furnace dust in the carburized material, the reduction rate of ZnO (s) was 5%.
The mixing ratio of the electric furnace dust and the carbonaceous material powder so as to be 0% or more was determined as follows.

The carburized material No. which was the test material in the above reduction experiment was used.
For each of BCA-40 and PCB-85, of the amount of C contained in the carburized material, the amount of C [C] _{Zn, eq} that can be apparently reacted for reducing ZnO is calculated based on the following formula (E). It was calculated using the component composition of each carburized material shown in Table 5.

[C] _{Zn, eq} = T. [C]-[C] _Fe-O ………………… (E) where [C] _{Zn, eq} : apparent C for reduction of ZnO in the carburized material
Amount (wt.%) [C]: Analytical value of total carbon content in carburized material (wt.
%) [C] _Fe-O : Calculated value of C equivalent required for reducing Fe ₂ O ₃ and FeO in the carburized material (wt.%)

Here, [C] _{Zn, eq} includes a portion which generates heat by burning and C for carburizing. The relationship between the apparent C amount [C] _{Zn, eq} for ZnO reduction and the reduction ratio α of ZnO determined above was plotted in FIG. FIG. In addition to the experimental data points P ₅₁ and P ₁₀ of the BCA-40 and PCB-85, ZnO in the case of the C content [C] = 0
The point P ₀ , which was considered to converge to a reduction ratio of 0, was plotted, and the relationship between [C] _{Zn, eq} and α was estimated with a curve A. Then, using the curve A, the reduction rate of ZnO α = 50%
The apparent C amount for the reduction of ZnO [C] _{Zn, eq} : xa _{, c} is obtained, xa _{, c} = 18.0 wt. %. Therefore,
Based on the following formula (F), the raw material mixture of the carburized material satisfying the above conditions was determined based on the electric furnace dust and the CD as the carbon material powder illustrated in Table 4.
Calculated using the component composition with Q powder, electric furnace dust: 80.7 wt. % CDQ powder: 19.3 wt. % (Provided that C% in PDA = 82.5 wt.% And PDA compounding ratio (%) = 9%). Therefore, the mixing ratio of the electric furnace dust and the CDQ powder was such that the electric furnace dust was 80 wt. % Was obtained.

In the above, [C] _{Zn, eq} = {[C] _EFD (X _EFD / 100) + [C] _CDQ (X _CDQ / 100) + [C] _PDA (X _PDA / 100)} − ｛[ C] _Fe2O3 + [C] _FeO ｝ (F) where [C] _Zn.eq : apparent C for reducing ZnO in the _carburized material
Amount (wt.%) [C] _EFD : C content in electric furnace dust (wt.%)
%) [C] _CDQ : C content in CDQ powder (wt.%) X _EFD : _Mixing ratio of electric furnace dust (wt.%) X _CDQ : Mixing ratio of CDQ powder (wt.%) X _PDA : PDA Mixing ratio (wt.%) X _EFD + X _CDQ + X _PDA = 100 [C] Fe ₂ O ₃ : C equivalent for reduction of Fe ₂ O ₃ in _carburized material (w
t. %) [C] _FeO : C equivalent for reduction of FeO in carburized material (w
t. %)

As can be seen from the above formula (F), when a carbonaceous material powder other than CDQ powder is used as the reducing material,
[C] The value of _CDQ changes. Further, the component composition of the electric furnace dust slightly changes depending on the source. Accordingly, the mixing ratio of the electric furnace dust in the raw material mixture of the carburized material described above also changes according to them. However, according to the experience of the present inventors, the content of C in the coke powder and the like and the electric furnace dust which can be supplied cheaply and stably as the carbonaceous powder is almost equal to the component composition shown in Tables 2 and 4. It is thought that it can be represented. In general, when the function of carburized material in electric furnace steelmaking is taken into consideration, the C content (%) in the raw material and the mixing ratio (%) of PDA as a binder change, and the C content is reduced. Even if it fluctuates by about 1%, it does not mean that the purpose cannot be achieved. Therefore, practically, in the present invention, the electric furnace dust is 80 wt.% In the mixing ratio of the electric furnace dust and the CDQ powder. % Is appropriate.

[2] Desirable Recycling Process of Electric Furnace Dust The present inventors have studied a recycling process of electric furnace dust satisfying the following conditions.

(A) The amount of electric furnace dust handled in the entire electric furnace factory is reduced, the amount of electric furnace dust transported to the factory of a company specializing in zinc recovery is reduced, and the total transportation cost is reduced. In order to increase the processing efficiency and reduce the cost in the zinc recovery factory, the electric furnace factory side can inexpensively and stably enrich Zn content in the electric furnace dust, (b) generated in the electric furnace factory As part of the process of treating electric furnace dust, the use of carburizing material for steelmaking produced from the electric furnace dust as a raw material in the electric furnace steelmaking operation allows recycling of electric furnace dust generated from the electric furnace. To be more stable,
(C) We considered a process that satisfies the three points of using existing equipment and minimizing new capital investment.

First, the following steps were conceived by paying attention to the component composition of the electric furnace dust and the fine powder properties thereof shown in Tables 1 to 3.

Conventionally, a Zn content of 15 to 20 wt. % Of electric furnace dust is transported from an electric furnace factory to a crude zinc oxide recovery factory for processing. While reducing this transport volume,
The operation efficiency in the crude zinc oxide recovery factory is improved by concentrating the ZnO content in the electric furnace dust. In order to carry out this, the method of utilizing the operation process itself of the electric furnace itself is used.
Concentrate nO.

(A) Dust generated from the electric furnace is collected as direct dust and building dust by an electric dust collector or the like.
This electric furnace dust is mixed with a carbon material powder such as inexpensive coke powder or coke extinguishing equipment collection powder (CDQ powder) as a reducing agent, mixed and mixed with a binder to produce a molded product such as a briquette. The carbon contained in the briquette has a function of reducing zinc oxide and iron oxide contained in the electric furnace dust in the briquette, and is commonly used in conventional electric furnace steelmaking operations. It has the same function as carbon in carburized wood.

At this time, it should be noted that the addition is started when the main material of the electric furnace is a solid charge that does not dissolve, and the carburizing material is added every time the main material is charged. That is, molten iron in the furnace,
Does not require the presence of hot metal. The function of starting reduction of the metal oxide in the electric furnace dust from a solid state stage is provided. Therefore, in addition to the amount of carbon equivalent to C equivalent required for oxide reduction, the amount of carbon for raising the temperature of the carburized material itself by combustion,
In addition, the amount of carbon corresponding to the reduction energy required to advance the reduction reaction is also required. The reason for starting the reduction from the electric furnace dust stage in the solid state is to make the steelmaking time and electric power consumption of the electric furnace within the same level as the conventional level even when the carburized material of the present invention is used. On the other hand, the electric furnace dust portion which has not been reduced in the solid state is made to contain enough carbon to be reduced by the carbon content in the carbonized material after the shift to the electric furnace molten slag. The surplus carbon in the carburized material is also used for reducing FeO, MnO, and the like in the slag, and part of the carbon is dissolved in the molten metal and carburized. By designing a carburized material having such a function, in the conventional electric furnace steelmaking operation, the amount of C supplied into the furnace by means other than the carburized material, for example, coke powder blowing into the furnace, electrode It is not necessary to particularly change the carbon balance at the time of the conventional stable operation, such as the dissolution of carbon from the alloy and the dissolution of carbon from the alloyed iron.

(B) The above carburizing material for steel making is charged into the electric furnace, and the Fe oxide in the electric furnace dust constituting the carburizing material is reduced to produce metallic Fe, and Zn oxide is produced. Is naturally oxidized in a furnace upper atmosphere to generate fine ZnO powder. Metal Fe is transferred to a steel bath later, ZnO powder is captured by a dust collector and transferred to electric furnace dust, and Zn is concentrated in electric furnace dust as compared with non-recycling of electric furnace dust.

(C) CaO and Si in electric furnace dust
O ₂ , Al ₂ O _3, MgO and the like are transferred to the molten slag in the furnace during the melting / oxidizing period. As a result, the amount of dust is reduced.

(D) Electric furnace dust generated during melting and refining of scrap containing zinc and inexpensive and highly reactive coke powder such as CDQ powder are used as main raw materials for the carburizing material. A predetermined binder is added to the raw material powder having the compounding ratio and the mixture is molded.

Thus, zinc is concentrated in the electric furnace dust, and the amount of electric furnace dust to be carried out of the electric furnace is reduced. Therefore, it is not necessary to provide a dedicated zinc oxide concentrating furnace in addition to the electric furnace on the electric furnace factory side, or the amount of electric furnace dust transported from the electric furnace factory to the zinc recovery factory is reduced. On the other hand, on the zinc recovery plant side, the electric furnace dust in which zinc is more concentrated than in the conventional case may be processed, so that the load on the processing operation is reduced and the processing cost is reduced.

FIG. 2 shows an example of an electric furnace dust recycling flow suitable for carrying out the above steps. A considerable portion of the electric furnace dust generated from the electric furnace steelmaking plant is recycled, and the remainder is transported to a specialized crude zinc oxide recovery plant as usual to recover Zn. The recycled electric furnace dust is mixed with CDQ powder, and a binder is added to form a briquette to produce a carburized material. This carburized material is used in the electric furnace steelmaking operation.

If the carburizing material for steelmaking is manufactured by the recycling flow of the electric furnace dust, the electric furnace for steelmaking can be regarded as a facility corresponding to a melting furnace for recovering zinc. Significant reduction in transportation costs for transporting electric furnace dust to the zinc recovery plant, increase in zinc content in electric furnace dust supplied to the crude zinc oxide recovery plant, and improved processing efficiency at the crude zinc oxide recovery plant And
Be streamlined.

Next, the present inventors prototyped carburized materials in which the mixing ratio of electric furnace dust was changed to various levels, measured the crushing strength and the trommel value, and formed the high melting point minerals in the slag. The presence / absence test was performed. As a result, it was found that if the mixing ratio of the electric furnace dust is in the range of 5 to 85, a carburized material having no problem in various characteristic values can be obtained. In Table 10,
The test results are shown.

[0080]

[Table 10]

However, regarding the maximum mixing ratio of the electric furnace dust, as described above, the viewpoint of securing the operation results of the electric furnace by setting the reduction ratio of ZnO in the electric furnace dust in the solid state to 50% or more. Therefore, it is desirable to set the dust mixing ratio to 80% or less.

The minimum mixing ratio of the electric furnace dust is desirably 30% or more as described below in consideration of the actual operation of the electric furnace dust recycling flow. That is, the present inventors have studied the operation of an electric furnace that produces 35,000 t / month of raw steel. Electric furnace dust is about 80
Ot / month occurs. In this case, in order to achieve a predetermined recycling effect by reducing the dust treatment cost and recovering the Fe and Zn contents contained in the dust, about 25% of the electric furnace dust generation amount of 800 t / month, that is, The trial calculation result that it is necessary to recycle 200t was obtained. On the other hand, the amount of carbon supplied by the carburizing material used in the conventional normal operation of the electric furnace is, for example, 10.37 kg / t-billet.
t. % Of CDQ powder, the required amount of CDQ powder Q _CDQ is approximately (10.37 kg / t-BT /
0.89) × (35000t-BT / 0.99t-BT)
/ T-molten steel) ≒ 412t. Therefore, the mixing ratio of electric furnace dust in the raw material mixture of carburizing material is $ 200 /
(200 + 412)｝ × 100 = 32.7 wt. %. From the above calculation results, the mixing ratio of the electric furnace dust was approximately 30 wt. % Was found to be suitable.

The present invention has been made based on the above-mentioned various findings, and the gist thereof is as follows.

In the method for producing a carburized material for steel making according to the first aspect of the present invention, a compounded raw material comprising an electric furnace dust and a carbonaceous material powder is prepared, a binder is added thereto, mixed, heated and dehydrated. And a method for producing a carburized material for steelmaking by molding the obtained granular semi-finished product by a molding machine, wherein the electric furnace dust is 30 to 80 wt. % In the range of 20 to 70 wt. % Of the above-mentioned carbonaceous material powder, and 5 to 10 w
t. % Of a hydrocarbon-based binder in the range of
The addition amount of the hydrocarbon binder is 5 to 10 wt. % Range
In the box, if the mixing ratio of the electric furnace dust is increased,
It is characterized by increasing both .

[0085] The method according to claim 2 steelmaking carburization material according the present invention, in the manufacturing method according to claim 1, wherein the coke quenching equipment collecting dust as the carbonaceous material powder, and the hydrocarbon
It is characterized by using propane di asphalting asphalt (PDA) as the basic binder.

[0086] The carburizing material for steelmaking according to the third aspect is the first aspect.
And at least carbon: 20-65 wt. % And zinc oxide: 8 to 2
3 wt. %.

According to the third aspect of the present invention, the total carbon content of the carburized material is from 20 to 65 as described above.
wt. %, Zinc oxide content from 8 to 23 wt. The reason for limiting to% is as follows.

That is, (1) the component composition is obtained based on the mixing ratio of each raw material and the binder in the production of the carburized material of the present invention, and (2) the composition obtained in this manner. As a result of using the carburized material having the above-mentioned composition in an electric furnace operation test for steelmaking, the function of carbon in the carburized material of the present invention, that is, iron contained in the electric furnace dust in the carburized material and The carbon for reduction of valuable metal oxides such as zinc, the carbon source as a partial substitute for the heat source by electric energy, and the function of the carbon addition source to molten steel are sufficiently exhibited. This is because zinc oxide in the carburized material is reduced and zinc in the electric furnace dust is sufficiently concentrated.

[0089] The carburizing material for steel making according to claim 4 is an electric furnace furnace.
A blending raw material consisting of a carbon fiber powder and
Add, mix, heat and dehydrate,
Carburizing for steelmaking in which powdered and granular semi-finished products are molded by a molding machine
Material, the electric furnace dust as the compounding raw material
30 to 80 wt. % In the range of 20 to 70 wt. %
Within the range of the above-mentioned carbonaceous material powder,
To 5 to 10 wt. % Charcoal in the range
The hydrocarbon is produced by adding a hydride binder.
The amount of the binder added is 5 to 10 wt. % Range
Therefore, the mixing ratio of the electric furnace dust was increased and
And at least total carbon (TC): 2
0 to 65 wt. % And zinc oxide: 8 to 23 wt. %
Is characterized by including the following . And claims
The carburizing material for steel making according to claim 5, is the carburizing material according to claim 3 or 4.
In the invention of the present invention, as the carbonaceous material powder,
Flour collecting, and propane di
Use asphalt asphalt (PDA)
In particular, it has features.

The method for recycling electric furnace dust according to claim 6 collects dust generated from the electric furnace for steelmaking, reduces oxides of valuable metal elements contained in the collected electric furnace dust, An electric furnace dust recycling method utilizing valuable metals as metal resources, having the following characteristics. That is, as a raw material, at least a part of the electric furnace dust is used, a raw material containing the same and a reducing material made of a carbon-containing material is prepared, and the prepared mixed raw material is molded into a lump, Manufactures carburizing materials for steel making for use in the steel making process. By using the carburizing material for steelmaking produced in this way in the operation of the electric furnace for steelmaking, the electric furnace for steelmaking is utilized as a device for reducing oxides of the valuable metals. Thus, an apparatus for reducing the oxide of the valuable metal is not separately provided.

[0091]

Next, an embodiment of the present invention will be described with reference to a schematic recycling flow of electric furnace dust shown in FIG.

Of the electric furnace dust W _d (t / month) generated from the electric furnace 1 having the raw steel production capacity W _M (t / month), α (%)
Is recycled as a raw material for carburizing, and the remaining 100-α
(%) To the specialized crude zinc oxide recovery plant 2.
Blended carbonaceous material powders such as CDQ powder or coke powder an electric arc furnace dust was recycled W _C and (t / month) at a predetermined ratio, and charged into the powder kneading apparatus 3, a binder W _b (t / month, such as a PDA )
Is added, mixed, heated and dehydrated, and the powdery semi-finished product thus prepared is molded into briquettes and pellets by a predetermined powder molding machine 4 to produce _a carburized material Wa for steelmaking.

[0093] electric furnace dust which approximately of its occurrence amount W _d 25
Recycle over 100% to ensure its economic effect. 30 to 80 wt. % In the range of carbon material such as CDQ powder. This was charged into the powder kneading device 3 and 5 to 10 wt. % Of the binder is added. Water, PD as binder
A, pitch, tar, starch, PVA, CMC, cement and the like are suitable. If a kneader with a high-speed rotary blade is used as the powder kneading device 3, mixing, heating and dehydration can be performed in a single container in a short time, which is efficient. The physical properties of the carburized material manufactured by the kneading machine and the molding machine are as follows: crushing strength: 35 kg / piece or more, trommel value: 85
% Or more, and high-melting-point mineral components are adjusted with the ash in electric furnace dust and CDQ powder already remelted and slag-ized so that high-melting-point minerals are not generated in slag.

In the raw material mixture ratio of the carburized material, the ratio of the electric furnace dust was 30 wt. The reason for limiting the percentage to at least% is from the viewpoint of ensuring the effect of recycling the electric furnace dust.
On the other hand, the ratio is 80 wt. %
In the solid state of reducing Fe oxides and Zn oxides in the carburized material, the reduction rate of the Fe oxide was adjusted to 100% and the reduction rate of the Zn oxide was adjusted to 50% or more. As in the case of the carburizing material of the above, the condition is that it can be used stably in the operation of the electric furnace. The details are as described above. The amount of binder to be added is 5-10
wt. The reason for limiting to the range of% is that the crushing strength and the trommel value of the carburized material satisfy the above range conditions, and the optimum value is determined depending on the type of the binder. The optimum value is determined by a physical test.

In the raw material of the carburized material, it is desirable that the carbon material powder has a high fixed carbon content, a low content of harmful elements to steel and slag, is inexpensive and can be supplied stably.
From this viewpoint, CDQ powder, coke powder, coke breeze, petroleum coke and the like are preferred. The reason why PDA is particularly desirable as a binder is that PDA has a carbonaceous material of 8%.
It is 2.5%, easy to use with a softening point of about 63 ° C., is solid at normal temperature, has water repellency, has high compressive strength after molding, and is hardly powdered. Further, when heated in a furnace, a reducing gas is released, but the molded briquette is not powdered, but maintains its shape up to a high temperature.

The composition of the carburized material thus produced slightly varies depending on the composition of the electric furnace dust and the carbon material powder used as the raw material. % And zinc oxide is 8 to 23 wt. %including. If these two components are within the above ranges, the economic effects of recycling the electric furnace dust can be secured.

[0097]

Next, the present invention will be described in more detail with reference to examples.

[1] Production test of carburized material and its use test (1) Test method From an electric furnace steelmaking plant that produces 35,000 t / month of raw steel and casts 74.9 t / heat of average good lump Using electric furnace dust generated and CDQ powder generated from a blast furnace coke plant as raw materials, adding an appropriate amount of PDA as a binder to compounding raw materials in various ratios, and using the production flow shown in FIG. Was manufactured on a trial basis. The mixing ratio of the raw materials is 30:70 to 85:15 by weight ratio of electric furnace dust and CDQ powder.
PDA was added at 6 to 9 wt. %. Using a kneader with a high-speed rotating blade as a powder kneading device, mixing, heating and
After dehydration, the mixture was molded by a briquette molding machine or granulated by a pelletizer. However, the pelletizer was used only when the raw material mixing ratio was 85:15. The component composition of the raw materials is the same as that shown in Table 4.

Table 11 shows the raw material blending ratio of the carburized material, the amount of the binder added, and the calculated composition of the carburized material. As a typical carburizing material, the mixing ratio of electric furnace dust and CDQ powder is 4
For the carbonized material at 0:60 (No. BCA-40), the component composition analysis value is shown. Table 12 also shows the carburized material No. used in the test. BCA-40, a carburized material No. out of the scope of the present invention. PCB-85 and conventional carburized N
o. The individual weight, volume, porosity, crushing strength, and trommel value of BC are also shown. In addition, No. BC is obtained by adding a binder to only CDQ powder, and its composition is as follows:
85 wt. %, Ash content: 10 wt. %, Volatile content: 4 wt.
%.

[0100]

[Table 11]

[0101]

[Table 12]

Each of the carburized materials shown in Tables 11 and 12 was used as a carburized material in electric furnace steelmaking. The method of using the test carburized material is as follows. It was used in combination with BC, and was added in a total of three times at the time of charging the raw material into the electric furnace and at the beginning of the subsequent dissolution in a total of three times. The molten steel type has a C concentration of 0.2 wt. %, The test operation using the carburized material was performed in accordance with the conventional standard smelting standard for the steel type. According to the mass balance sheet of the amount of C during the operation of the electric furnace according to the standard smelting standard, the amount of C supplied into the furnace during the oxidizing and refining period (including the melting period) is the main raw material consisting of scrap iron and pig iron, Material (carburized material No. BC), carbon powder blown into the furnace and a total of 19.62 kg / t- billet (hereinafter referred to as “t”) supplied from the electrode.
-BT "), of which the amount of C supplied from the carburized material is 10.37 kg / t-BT. The amount of C in the molten metal (molten steel) at the end of the oxidation refining period is 0.1%.
It is 75 kg / t-BT.

The criterion for determining the amount of the test carburized material is based on the mass balance of the above-mentioned C amount, and is based on the conventional carburized material (No. B).
The test carburized material substituted for C) is (a) Fe oxide (Fe ₂ O ₃ and F ₂ ) in the electric furnace dust contained in the carburized material.
eO) and the reduction rate α of ZnO estimated from the curve A shown in FIG. 1 among Zn oxides (ZnO).
(%) The amount of C required to reduce the component in a solid state,
(B) C amount for reaction energy (ΔH) required for progress of the reduction reaction of each oxide, (c) C amount for heat amount (Q _T ) required for heating the carburized material to a predetermined temperature T ,
(D) C content for carburizing to molten steel component, and (e) above (b)
Except for (c) and (c), the total amount of C that partially substitutes for electric energy was secured.

Here, the reduction reaction of each oxide in the above item (a) is carried out by the above-mentioned (A), (a-3) and (C), respectively.
Equation (2), the reaction energy of the term (b) (ΔH)
Are the following (G-1), (G-2) and (G-3), respectively.
Using the equation, the required heat quantity Q _{T of the} term (c) is expressed by
It was calculated based on the equation.

ΔH _Fe2O3 = 670 kcal / kg-Fe ₂ O ₃ (G-1) ΔH _FeO = 370 kcal / kg-FeO (G-2) ΔH _ZnO = −345 kcal / kg-ZnO …… (G-3) Q _T = 0.41 kcal / kg-Carbonized material ……… (H)

Considering the in-furnace reaction characteristics in the electric furnace steelmaking operation, the behavior of C in the carburized material during the refining and refining period of the operation test using the test carburized material is based on the conventional carburized material under the standard operating conditions. The behavior of C may be regarded as the same. Therefore, in the test operation, the reaction behavior until the end of the oxidation refining period is important.

Tables 13 and 14 show the use conditions of the test carburized material and the conventional carburized material (carburized material No. BC), and the main electric furnace operating conditions and operation results. However, carburizing material N
o. The operation test using PCB-85 showed that the content of C was 1
6.2 wt. %, And C = 10.3 required for steelmaking operation
To secure 7 kg / t, the carburized material No. PCB-85
A simple addition requires a high addition amount of 64 kg / t. Not performed because it is similar to BCA-80.

[0108]

[Table 13]

[0109]

[Table 14]

(2) Test Results The results of each of the above operation tests will be described below.

[Comparative Example 1 Carburized material No. BC] This is a case where a conventional carburized material is used under conventional standard operating conditions. The total amount of the carburized material was added by the time of the oxidizing refining period, and the amount used was 12.2 kg / t-BT. The fixed C amount supplied from the carburized material was 10.37 kg / t-B as described above.
T. In standard operation, the amount of slag is 58.7 kg /
t-BT, slag basicity CaO / S during oxidative refining
iO ₂ is 1.59. The steelmaking time is 61 minutes, and the power consumption in the oxidation refining period (including the melting period; the same applies hereinafter) is 320.
kW / t-BT.

In the following operation using the test carburized material,
The slag basicity and basic operating conditions are adjusted to the standard operating conditions described above. As described above, the operability of the test carburized material is focused on by the end of the oxidizing and refining period, and the operation performance is evaluated in units of heat as appropriate.
It was compared with the case of using BC.

Example 1 Carburized material No. BCA-80
Part 1] Carbide No. 14 kg / t-B of BCA-80
T, no. 9.17 kg / t-BT BC
Was added in total of 23.17 kg / t-BT. There was no problem with the operability due to the addition of carburized material. Basic unit of slag during standard operation: Basic unit of lime at 1.59 is 17.4 kg /
t-BT. On the other hand, in consideration of the ash content of the electric furnace dust in the carburized material and the mixing of SiO ₂ contained therein,
In order to adjust the slag basicity to the standard value of 1.59, 1.3 kg / t-BT of lime was additionally added. The amount of slag generated increased by 6.25 kg / t-BT. On the other hand, the steelmaking time was 62 minutes, which was almost the same as the standard value of 61 minutes, but the power consumption during the oxidation refining period was 325 kWh / t-BT, which was slightly increased from the standard value of 320 kWh / t-BT. In addition, molten steel yield ((f / e) × 100% (where, f: amount of molten steel tapped, e: charged amount = (main raw material + alloy iron + carburized material No. B)
Fe content in CA-80. The same applies to standard operation)
From f = 75,950kg and e = 80,290kg,
(F / e) × 100 = + 0.2% higher than 94.6%. This is because Fe contained in the electric furnace dust in the carburized material
It is considered that this is because the metal Fe generated by the reduction of the oxide was transferred to the molten steel through the oxidation refining period and the reduction refining period.

[Example 2 Carburized material No. BCA-80
Part 2] Carburized material No. 7 kg / t-B of BCA-80
T, no. BC is 10.5kg / t-BT
Of 17.5 kg / t-BT was added. There was no problem with the operability due to the addition of carburized material. In order to adjust the slag basicity to the standard value of 1.59, the amount of lime added was 17.4 kg / t-BT of standard lime in consideration of the mixing of SiO _{2 in} the ash of the electric furnace dust in the carburized material. 1.16kg
/ T-BT was added. The amount of slag generated is 3.64kg
/ T-BT. Steelmaking time and power consumption during the oxidizing and refining period were not different from the standard operation. In addition, the molten steel yield was + 0.1% higher than in the standard operation. This is considered to be because metal Fe generated by reduction of Fe oxide contained in the electric furnace dust in the carburized material was transferred to molten steel. In all of Examples 4 to 10, the molten steel yield was high. The reason is the same as above.

[Example 3 Carburized material No. BCA-80
Part 3] No. Using only BCA-80, 62 kg / t-BT was added. Since the amount of the carburizing agent added was large, the amount was added in three equal portions in order to suppress the amount added per operation. Nevertheless, as an operability problem associated with the addition of the carburizing agent, after the addition of the carburizing agent, the carburizing material was deposited between the electrode, the carburizing material, and the scrap iron, and the current interruption phenomenon often occurred. Violent boiling occurred during the later stage of melting, and a large amount of iron-containing slag flowed out. This resulted in iron loss. Steelmaking time took 71 minutes, a significant extension from the standard 61 minutes. In addition, the basic unit of electric power during the oxidizing and refining period is 338 kWh / t-BT, which is 1 unit less than the standard operation.
It increased by 8 kWh / t-BT. In order to adjust the slag basicity to the standard value of 1.59, the amount of lime added was 2.22 kg / t to the standard lime basic unit of 17.4 kg / t-BT.
t-BT was added. In addition, the amount of slag generated increased by 24.2 kg / t-BT from the time of the standard operation to 82.9 kg / t-.
It was BT and increased significantly. From these results, carburized material No. It is inappropriate to use BCA-80 alone, and the conventional carburized material No. It is necessary to reduce the total amount of addition by using together with BC. The molten steel yield was -0.6%, which was not higher than that in the standard operation.

Example 4 Carburized material No. BCA-65
Part 1] Carbide No. 17 kg / t-B of BCA-65
T, no. BC was added at a total of 23 kg / t-BT, 6 kg / t-BT. There was no problem with the operability due to the addition of carburized material. In order to adjust the slag basicity to the standard value of 1.59, the lime addition amount is 17.4 kg / l at the standard time of lime in consideration of the ash content of the electric furnace dust in the carbonized material and the SiO ₂ content contained therein. 1.3 for t-BT
kg / t-BT was added. The amount of slag generated was 6.27.
kg / t-BT. The steelmaking time is 62 minutes, which is almost the same as the standard operation, but the power consumption during the oxidation refining period is 3
320 kWh / t in standard operation at 25 kWh / t-BT
-Slightly higher than BT. In addition, the molten steel yield was + 0.2% higher than in the standard operation.

Example 5 Carburized material No. BCA-65
Part 2] No. Using only BCA-65, 34 kg / t-BT was added. There was no problem with the operability due to the addition of carburized material. Standard value of slag is 1.59
In consideration of the ash content of the electric furnace dust in the carburized material and the mixing of SiO ₂ contained therein, the amount of lime added is set to 17.4 kg / t-BT per unit lime at the standard time.
5 kg / t-BT was added. The amount of slag generated was 11.
It increased by 51 kg / t-BT. The steel making time was 64 minutes, slightly longer than the standard operation. The basic unit of electric power during the oxidizing and refining period is 329 kWh / t-BT and 320 kWh /
It increased from t-BT. Test carburized material No. BCA-6
If the test conditions are sufficient to cover the entire amount of carburized wood in 5, the continuity of actual operation is sufficient. In addition, the molten steel yield was + 0.4% higher than in the standard operation.

Example 6 Carburized material No. BCA-50]
No. as carburizing material. Using only BCA-50, 24k
g / t-BT was added. There was no problem with the operability due to the addition of carburized material. In order to adjust the slag basicity to the standard value of 1.59, the lime addition amount is 17.4 kg / l at the standard time of lime in consideration of the ash content of the electric furnace dust in the carbonized material and the SiO ₂ content contained therein. 1.2kg / t for t-BT
-Added BT. The amount of slag generated is 6.96 kg / t.
-Increased by BT. The steelmaking time is 63 minutes, slightly longer than the standard operation, and the unit electricity consumption during the oxidation refining period is 325 kWh /
At t-BT, it was slightly increased from 320 kWh / t-BT in the standard operation. The molten steel yield is +0.
4% higher.

Example 7 Carburized material No. BCA-40
Part 1] No. Using only BCA-40, 20 kg / t-BT was added. There was no problem with the operability due to the addition of carburized material. Standard value of slag is 1.59
In consideration of the ash content of the electric furnace dust in the carburized material and the mixing of SiO ₂ contained therein, the amount of lime added is set to 17.4 kg / t-BT per unit lime at the standard time.
2 kg / t-BT was added. The amount of slag generated was 5.2.
It increased by 6 kg / t-BT. The steelmaking time was 62 minutes, which was almost the same as in the standard operation, but the power consumption in the oxidation refining period was 324 kWh / t-BT, which was slightly increased from that in the standard operation. The molten steel yield is + 0.4% compared to the standard operation.
Got higher.

Example 8 Carburized material No. BCA-40
Part 2] No. Only BCA-40 was used and 27 kg / t-BT was added. There was no problem with the operability due to the addition of carburized material. Standard value of slag is 1.59
In consideration of the ash content of the electric furnace dust in the carburized material and the mixing of SiO ₂ contained therein, the amount of lime added is set to 17.4 kg / t-BT per unit lime at the standard time.
6 kg / t-BT was added. The amount of slag generated is 7.0
It increased by 9 kg / t-BT. The surplus carbon content due to the addition of the carburizing material was large, the leaching [C]% was high, and time was required for decarburization. In addition, the power consumption rate during the oxidation refining period is 326 kWh /
t-BT and increased by 6 kWh / t-BT from the time of the standard operation. The molten steel yield is + 0.2% compared to the standard operation.
Got higher.

Example 9 Carburized material No. BCA-30
Part 1] No. Only BCA-30 was used, and 16.5 kg / t-BT was added. There was no problem with the operability due to the addition of carburized material. Standard value of slag basicity
In order to adjust to 59, in consideration of the ash content of the electric furnace dust in the carburized material and the SiO ₂ content contained therein, the amount of lime added was reduced to a standard lime basic unit of 17.4 kg / t-BT,
1.0 kg / t-BT was added. In addition, the increase in the amount of slag produced was due to the electric furnace dust compounding ratio of the carbonized material being 30 wt. %, The increase was only 3.93 kg / t-BT. As a result, the heat load is small, the steelmaking time is 61 minutes as in the standard operation, and the power consumption during the oxidation refining period is 320 k.
Wh / t-BT. Moreover, the molten steel yield was + 0.1% higher than in the standard operation.

Example 10 Carburized material No. BCA-30
Part 2] No. Using only BCA-30, 20 kg / t-BT was added. In order to adjust the slag basicity to the standard value of 1.59, in consideration of the ash content of the electric furnace dust in the carbonized material and the contamination of the SiO ₂ contained therein,
The amount of lime added is 17.4 kg / t-B of lime intensity at standard time.
1.3 kg / t-BT was added to T. In addition, the amount of slag produced increased by 4.75 kg / t-BT. Excessive carbon content due to the addition of carburizing material required too much time for decarburization of molten steel after meltdown, and the steelmaking time was extended by 2 minutes from the standard operation to 63 minutes. Power consumption is also 32
4 kWh / t-BT, 4 kWh / t-BT from standard operation
t-BT increased. In addition, the molten steel yield was + 0.1% higher than in the standard operation.

In any of the tests of Examples 1 to 10, the ash contained in the dust in the test carburized material that was not reduced by the end of the refining and refining period was absorbed by the molten slag in the furnace. Accordingly, the electric furnace dust was reduced in volume from powder to slag by this amount.

(3) Overall Effect of Electric Furnace Dust Recycling From the above results, when the carburized material according to the present invention is used in the electric furnace steelmaking operation, it depends on the amount added and whether or not it is used in combination with the conventional carburized material. Quantitative data on changes in operability and power consumption were obtained. Therefore, the total effect of recycling electric furnace dust is estimated. The evaluation of the overall effect was based on the conventional carburized material No. under standard operating conditions. The operation result of Comparative Example 1 using BC was used as a reference.

Table 15 shows the calculation results of the total effect.

[0126]

[Table 15]

[0127]

As described above, according to the present invention, the following effects are exhibited.

The amount of dust carried out of the electric furnace factory is reduced. The iron yield in the electric furnace is improved (+ 0.1-0.
About 4%). Zn in the electric furnace dust can be concentrated in normal operation in the electric furnace without using a special melting furnace or the like (Zn = concentrated from 20% to 31%). A dedicated concentrating furnace for concentrating Zn in electric furnace dust is unnecessary. The electric furnace dust in the form of powder can be made into slag to reduce the volume and make it easy to handle. The product of the present invention can be manufactured only by utilizing the conventional carburizing material manufacturing equipment for steelmaking, which is commonly used, and the operation rate of the equipment is also improved. As the concentration of Zn in electric furnace dust increases, existing Z
n The load on the recovery plant is reduced. The amount of recovery of Zn resources in electric furnace dust increases, and the amount of electric furnace dust disposed of decreases, contributing to environmental improvement. The present invention provides a carburizing material for steelmaking and a method for producing the same, which exhibit the above-mentioned effects, and also provides an effective method for recycling electric furnace dust, which has industrially useful effects.

[Brief description of the drawings]

FIG. 1 is a graph for estimating a relationship between an apparent carbon content that can be used to reduce ZnO contained in a carburized material and a reduction rate of ZnO.

FIG. 2 is a view showing a schematic recycling flow of electric furnace dust suitable for producing the carburized material for steelmaking of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electric furnace 2 Crude zinc oxide recovery factory 3 Powder kneading apparatus 4 Powder molding machine 5 Electric furnace dust 6 Carbon material powder 7 Binder 8 Carburizing material for steel making

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-10-158718 (JP, A) JP-A-60-169512 (JP, A) JP-A-10-158714 (JP, A) JP-A 10-158 195514 (JP, A) JP-A-6-330132 (JP, A) JP-B-60-56407 (JP, B2) JP-B-1-35885 (JP, B2) (58) Fields investigated (Int. ⁷ , DB name) C21C 7/00 101 C21C 5/52

Claims (6)

(57) [Claims] 1. A blended raw material comprising electric furnace dust and carbonaceous material powder is prepared, a binder is added thereto, mixed, heated, and dewatered, and the resulting powdery and granular semi-finished product is molded by a molding machine. A method for producing a carburized material for steelmaking, wherein the electric furnace dust contains 30 to 80 wt. % In the range of 20 to 70 wt. % Within the range of the carbon material powder, and 5 to 10 wt. % Of the hydrocarbon-based binder is added, and the amount of the hydrocarbon-based binder added is 5 to 10%.
wt. %, And increasing and increasing the mixing ratio of the electric furnace dust within the range of%. 2. A powder collected from a coke extinguishing system as the carbonaceous material powder, and propane di asphalting asphalt (PDA) as the hydrocarbon-based binder.
The method for producing a carbonized material for steelmaking containing electric furnace dust according to claim 1, wherein: 3. A mixed raw material comprising electric furnace dust and carbonaceous material powder is prepared, a binder is added thereto, mixed, heated, and dewatered, and the obtained granular semi-finished product is molded by a molding machine. A carburizing material for steelmaking, wherein the electric furnace dust is 30 to 80 wt. % In the range of 20 to 70 wt. % Within the range of the carbonaceous material powder, and 5 to 1 of the compounding raw material with respect to the compounding raw material.
0 wt. % Of the binder and at least total carbon (TC): 20-65 w
t. % And zinc oxide: 8 to 23 wt. % Carbonized steel for electric steelmaking containing electric furnace dust. 4. A blended raw material comprising electric furnace dust and carbonaceous powder is prepared, a binder is added thereto, mixed, heated, and dewatered, and the obtained granular semi-finished product is molded by a molding machine. A carburizing material for steelmaking, wherein the electric furnace dust is 30 to 80 wt. % In the range of 20 to 70 wt. % Within the range of the carbonaceous material powder, and 5 to 1 of the compounding raw material with respect to the compounding raw material.
0 wt. % Of a hydrocarbon-based binder is added, and the amount of the hydrocarbon-based binder added is 5 to 1%.
0 wt. %, The electric furnace dust is produced with increasing and increasing proportions of the electric furnace dust, and at least total carbon (TC): 20 to 65 wt. % And zinc oxide: 8 to 23 wt. % Carbonized steel for electric steelmaking containing electric furnace dust. 5. A powder collected from a coke extinguishing system as the carbonaceous material powder, and propane di asphalting asphalt (PDA) as the hydrocarbon binder.
The carbonized material for steelmaking containing electric furnace dust according to claim 3 or 4, characterized by using: 6. An electric furnace dust that collects dust generated from an electric furnace for steelmaking, reduces oxides of valuable metal elements contained in the collected electric furnace dust, and utilizes the valuable metal as a metal resource. In the recycling method, a raw material containing at least a part of the electric furnace dust and a reducing agent made of a carbon-containing substance is prepared, and the prepared compounded raw material is molded into a lump and used in the electric furnace steelmaking process. By manufacturing the steelmaking carburized material, by using the steelmaking carburized material thus manufactured in the operation of the steelmaking electric furnace, the steelmaking electric furnace is used as a device for reducing oxides of the valuable metal. An electric furnace dust recycling method characterized by utilizing.