JPH01180920A - Treatment of secondary dry dust of blast furnace - Google Patents

Abstract

PURPOSE:To utilize the effective components in the secondary dust of a blast furnace raw material at a high recovery rate by classifying the secondary dry dust exhausted from the blast furnace into a primary coarse grain component and primary fine grain component, secondarily classifying the primary grain component further by a dry process and reutilizing the dust except the secondary fine grain component as a raw material for iron making. CONSTITUTION:The waste gas emitted from the blast furnace is passed through a gravity dust remover 2, a dry dust collector 3, by which the dust in the blast furnace gas is separated and recovered as the secondary dry dust. This recovered blast furnace secondary dry dust is classified by primary classification 4 to the primary coarse grains 5 and the primary fine grains 6. The content of Zn in the primary coarse grains 5 is low and the content of Fe and coke powder therein is high; therefore, said grains are used straightly as the raw material for steel making. The primary fine grains 6 are dried 8 and are then disintegrated 9 if necessary, by which the grains are secondarily classified to the secondary coarse grains 11 and the secondary fine grains 12. The secondary coarse grains 11 contain the Fe and C at a high ratio and the Zn at a less ratio and are, therefore, reutilized as the raw material for iron making. The Zn is thickened in the secondary fine grains 12 and the Fe and C are less contained therein. Said grains are consequently utilized as the raw material 13 for Zn.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention uses a dry dust catcher to collect secondary dry dust from a blast furnace, that is, dust discharged together with blast furnace gas.
The present invention relates to a method for processing dust collected by a dry dust collector.

[Conventional technology]

Since the blast furnace secondary dry dust contains a large amount of Fe and 0% (for example, Fe: 30-35%, C: 25-35%), a method of reusing it as a raw material for iron manufacturing has been conventionally performed. However, since it also contains about 2 to 7% of Zn, if it is used as a raw material for iron production, the Zn content will be concentrated, leading to instability in blast furnace operation such as poor ventilation of the blast furnace and poor unloading.

Therefore, (1) Japanese Patent Publication No. 56-14131 proposes to wet-classify secondary blast furnace dust to obtain high-Fe-containing dust and high-Zn-containing dust, and to use the high-Fe-containing dust as a raw material for iron manufacturing. , (2) JP-A-60-159132 discloses that secondary dry blast furnace dust is classified using a variable classifier, and high Fe-containing dust is used as a raw material for iron manufacturing.

[Problem that the invention seeks to solve]

However, in the method (1) above, blast furnace dust is obtained as wet secondary blast furnace dust using a venturi scrubber or the like, and then high Fe-containing dust is obtained using a classification device such as a wet cyclone. It requires equipment such as a dehydrator, which increases the equipment cost, (b) the running cost increases due to processing the collected dust water, and (c) it is a wet type, so it is difficult to handle after classification. be.

On the other hand, method (2) obtains secondary blast furnace dust using a dry method, so it does not have the above-mentioned problems (a) to (c). However, in this method, the high Zn-containing dust after the primary classification, which is not used as a raw material for steelmaking, contains, for example, Zn as shown in Table 1, as well as a large amount of Fe and Zn. Their recovery rates were low.

Table 1 Therefore, the main object of the present invention is to provide a treatment method that significantly improves the recovery rate of Fe and 0.

[Means for solving problems].

The present invention for solving the above-mentioned problems involves firstly classifying the blast furnace 2 finished product into a primary coarse grain fraction and a primary coarse grain fraction in a dry method, and using the primary coarse grain fraction as a raw material for iron making. , the primary coarse particles are dry classified into secondary phase particles and secondary coarse particles, and the secondary phase particles are also used as a raw material for iron manufacturing.

[For production]

In view of the above-mentioned problems with the method (1), the present inventors further pursued the process of adopting the method (2) and found that the Zn content rate for each particle size of high Zn-containing dust When we investigated, we obtained the results shown in Figure 3.

According to the results, it was found that Zn was concentrated in fine particles, and Fe and C were concentrated in coarse particles.

This is the same way of thinking when performing primary classification. As described above, the following are the reasons why effective components such as Fe and C in the primary assembled grains (high Zn-containing dust) are not sufficiently recovered in the primary classification. In other words, in general, the narrower the particle size range of the dust to be classified, the better the classification efficiency. The particle size range of Blast Furnace 2 Completion Task is as wide as 0 to 149 μm, so the classification efficiency is extremely poor. ■ Blast Furnace Secondary Dry Dust I
- contains hygroscopic components such as Na, K, Cβ, and Ca, although in small amounts, during classification, by absorbing moisture in the air, fine particles containing a large amount of Zn may adhere to each other or Large diameter pseudo particles are formed by adhering to the surface of coarse particles with low content, and as a result of classification,
It mixes with the coarse particles and is collected.

For these reasons, the present inventors noticed that the recovery rate of Fe and 0 fractions could not be sufficiently increased by primary classification alone.

Therefore, the present inventors made the following improvements.

(1) The particle size range of the primary assembled grains generated by the primary classification is 0 to 44 μm, and that of the primary classification (0 to 149 μm).
(μm), so if the primary aggregate has a moisture content of 1% or less, direct secondary classification will result in Z
Secondary aggregates with a low n content can be obtained.

(2) As mentioned above, -0.5 to 3% contained in the second set of grains
A certain degree of moisture causes pseudo-particle formation.

Therefore, the moisture content of the primary aggregate after primary classification is 1%.
In the above case, secondary assembled particles with a low Zn content can be obtained by increasing the dispersibility of the pseudoparticles by drying and then performing secondary classification.

(3) Even if the moisture content of the primary aggregate is 1% or less, the dispersibility of the pseudo particles is poor due to fluctuations in dust components, or the moisture content is high and the dispersibility of the pseudo particles is insufficient with drying alone. In order to avoid destroying the coarse particles of the primary aggregate as much as possible, a crushing process is performed to remove only the fine particles attached to the coarse particles, and the pseudo particles are dispersed. After increasing the Zn content, by performing secondary classification,
Next, agglomerated grains can be obtained.

As described above, in the present invention, the primary aggregated grains after the primary classification are directly classified through drying and crushing, or after drying and crushing, and then subjected to secondary classification, and the secondary aggregated grains and secondary assembled grains are Separated into grains, Zn
Since the secondary aggregate grains containing a small amount of <, Fe, and a large amount of
and the recovery rate at 0 minutes is further increased.

[Specific structure of the invention]

The present invention will be explained in more detail below.

FIG. 1 shows the processing flow of the method of the present invention. After passing through the gravity dust remover 2 consisting of a dust catcher, the blast furnace gas from the blast furnace reaches a dry dust collector 3, such as a high filter. Here, the tast included in it is blast furnace 2
It is collected as a fulfillment task.

This collected blast furnace 2 completion dust is first classified 4,
It is divided into a primary assembled grain 5 and a primary assembled grain 6, and the primary assembled grain 5 is used as a raw material 7 for iron making.

In the present invention, the primary aggregated grains 6 are directly dried 8 and then crushed 9, or after dried 8 and crushed 9, and then the secondary phase grains 1) and the secondary aggregated grains 12 are formed into secondary phase grains 1) and secondary aggregated grains 12. After classification, the secondary phase grains 1) are used as a raw material for iron manufacturing 7, and the secondary assembled grains 12 are sold 13 to external parties such as zinc manufacturers.

Here, in the stage of primary classification, it is desirable to set the large diameter side as the classification point compared to the case where the method of the present invention is not adopted, and the classification point is preferably 23 to 40 μm. The classification point in the secondary classification is preferably 5 to 12 μm.

It is desirable to perform both the primary classification and the secondary classification using a dry method.The model is not limited as long as it is a dry method and can perform classification at the above-mentioned classification points, but for example, a micron separator manufactured by Hosokawa Micron■ "MS series" or "Accucut" made by Donaldson Japan can be used. Both classifiers can be used for both primary and secondary separation, since the classification ability can be changed mainly by the rotor rotational speed and air volume.

Since the drying and crushing operations affect the Zn removal rate as shown in FIGS. 4 and 5, it is desirable to appropriately determine them based on the type of equipment, its operating conditions, and cost. In addition, the Zn removal rate at the time of secondary classification referred to here is (
1).

A: Dust weight before classification (kg) B: Dust Zn content before classification (%) C: Coarse dust weight after classification (kg) D 2 Coarse dust Zn content after classification (%) [Example] 1st When the method of the present invention was applied according to the process flow shown in the figure, the change in Zn content shown in FIG. 2 was observed.

The figure in parentheses is the dust weight distribution ratio when the weight of the blast furnace 2 finished dust is set as 100.

As a result, the conventional blast furnace 2 achieved dust weight of 55 to 7
Although only 0% of the raw material was used as a raw material for iron production, when the method of the present invention is adopted, the utilization rate increases to 85 to 90%. In addition, Zn is 14 to 25 in the secondary aggregated dust.
%, making it possible to fully utilize it as a Zn raw material.

On the other hand, an example of recovery of T, Fe and 0 minutes from the primary aggregated grains is as follows:
As shown in Table 2, high Fe and C recovery rates were observed.

Table 2 (Note) The unit of numerical value is % [Effects of the invention] As described above, according to the present invention, raw materials for steel manufacturing can be recovered with a high recovery rate, which is sufficient compared to the capital investment cost. .

[Brief explanation of the drawing]

Fig. 1 is a processing flow diagram of the method of the present invention, Fig. 2 is a diagram showing the Zn content and weight distribution proportion for each processing stage, and Fig. 3 is a diagram showing the particle size and Zn content of the primary aggregate after primary classification. Correlation diagram, Figure 4 is 1
Figure 5 is a relationship diagram between dust moisture and Zn removal rate of the next aggregated grain.
It is a correlation diagram of the secondary assembly grain recovery rate and the secondary assembly grain removal rate. Patent applicant Sumitomo Metal Industries Co., Ltd. Representative Patent attorney Yoshihisa Nagai: ′−゛−・
−′: So (so fence edict)

Claims (1)

[Claims] (1) The secondary dry blast furnace dust is first classified into primary coarse particles and primary fine particles using a dry method, and the primary coarse particles are used as raw material for steelmaking, and the primary fine particles are classified using a dry method A method for treating secondary dry blast furnace dust, characterized in that it is secondarily classified into a secondary coarse particle fraction and a secondary fine particle fraction, and the secondary coarse particle fraction is also used as a raw material for iron manufacturing.