JPH09272925A - Production of sintered ore excellent in property at high temperature and cold strength - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing sintered ore by which cold strength, low temp. reduction powdering property, and property to be reduced are simultaneously improved and for which a means has not yet established. SOLUTION: Lime stone D is adjusted or pelletized so that the content of the particles having 3 to 5mm grain size is <=15wt.% and a material to be sintered is compounded with the lime stone D. Then, auxiliary raw material A containing MgO such as serpentine, nickel slag or the like is adjusted or pelletized so that the content of the particles having 0 to 0.5mm grain size is >=30wt.% and that of the particles having 1 to 5mm grain size <=50wt.% and the material to be sintered is compounded with the auxiliary raw material A. Then, whole the compounded materials are blended, pelletized and calcined in a sintering machine 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a sinter having excellent high temperature properties and cold drop strength.

[0002]

2. Description of the Related Art Conventionally, sinter ore has been used as a raw material for sintering, and in addition to iron ore, auxiliary raw materials such as limestone and serpentine are mixed and mixed, and the mixed raw material is granulated by a granulator and then sintered. It is manufactured by firing with a machine. At this time, limestone is blended as a CaO source to melt with iron ore and generate a low melting point melt to form a binder phase. Serpentine, nickel slag,
Junite is blended for the purpose of improving the high-temperature properties of the sinter by modifying the slag composition in the blast furnace as a MgO source while strengthening its binder phase as a SiO ₂ source.

Many attempts have been made to increase or decrease the specific particle size of these auxiliary materials in order to improve the productivity and quality of the sintered ore.

For example, Japanese Unexamined Patent Publication (Kokai) No. 63-228216 discloses a method for producing a sinter having a high reducibility by adjusting the serpentine to 50 wt% to 1 to 10 mm. However, this method causes reductive pulverization of the sintered ore in the blast furnace, and no countermeasure is described for it.

On the other hand, in Japanese Unexamined Patent Publication (Kokai) No. 57-188626, Ni slag is treated with a Blaine index of 500 to 1000 cm ² / g.
A method for producing a sinter having a low low-temperature reduction powderability is disclosed by pulverizing to a particle size (which is considered to be equivalent to 0.05 to 0.5 mm when converted to a particle size). However, this method causes deterioration of cold strength and reducibility, and measures against it are not described.

In Japanese Patent Laid-Open No. 60-248826, limestone is added to 0.5 to 2 mm, silica stone, serpentine, and SiO ₂ are added to 4
There is disclosed a method for producing a sintered ore which is excellent in JIS reduction rate and low-temperature reduction pulverization property, in which powder iron ore of at least 1% is adjusted to be 1 to 2 mm. However, it does not describe cold strength.

[0007]

DISCLOSURE OF THE INVENTION The present invention provides a method for producing a sinter that simultaneously improves cold strength, low-temperature reductive pulverization property and reducibility, which means have not been established until now. To aim.

[0008]

The summary of the present invention is as follows.

In producing a sintered ore containing iron ore,
The particle size of limestone is adjusted or granulated so that 3 to 5 mm is 15 wt% or more and blended in the sintering raw material, and the particle size of the MgO-containing auxiliary material is 0 to 0.5 mm is 30 wt% or less, 1 to 5
mm is adjusted to 50 wt% or more or granulated and blended in the sintering raw material, and then the entire blended raw material is mixed and granulated, and then fired by a sintering machine. A method for producing a sintered ore having excellent cold strength.

A sinter having excellent high-temperature properties and cold strength is characterized in that -1 mm of the MgO-containing auxiliary raw material is granulated to form a granulated product having a size of 1 mm or more and blended in the sintering raw material. Production method.

The method for producing a sinter having excellent high-temperature properties and cold strength, characterized in that one or two of serpentine, nickel slag, and dunite is used as a MgO-containing auxiliary material.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION In order to solve the above-mentioned problems, the present invention has a high cold strength by adjusting the particle size distribution of limestone, serpentine, nickel slag, and dunite mixed in a sintering raw material before firing. , Sinter that has low low-temperature reduction powderability and excellent high-temperature reducibility is manufactured. In addition, each chemical component is illustrated in Table 1.

[0013]

[Table 1]

According to the present invention, first, the fine powder portion of limestone is greatly reduced to improve the air permeability in the sintering raw material layer. As a result, the sintering productivity is improved, and since the heat pattern for firing is sharpened, secondary hematite, which is one of the factors of low-temperature reduced powder, is reduced, and low-temperature reduced powder is improved. However, in this case, the fine powder of limestone, which is the starting point of the generation of the initial melt in the sintering process, is reduced, so that the yield and the cold strength are reduced. Therefore, in order to suppress the reactivity of MgO, which has the effect of raising the melting point of the melt, the fine powder portion of serpentine, nickel slag, and dunite, which are MgO sources, is greatly reduced. As a result, the yield and cold strength are suppressed from being lowered, and the stabilizing effect of magnetite by MgO is also suppressed, so that the magnetite with poor reducibility is reduced and the reducibility is improved.

According to the method of the present invention, the particle size of limestone is 3 to 5 mm is 1
The reason for setting the content to 5% or more is that when the grain size of limestone is made coarser than this in the pot test, limestone is not assimilated and remains in the sintered ore, resulting in a decrease in yield and cold strength.

The grain size of the MgO source such as serpentine, nickel slag, and Junite is 0 to 0.5 mm and 30 wt% or less,
The reason why 1 to 5 mm is set to 50 wt% or more is that, based on the results of basic experiments, serpentine with a diameter of 0.125 mm or less significantly suppresses assimilation of limestone and may cause a decrease in yield and cold strength. This is because it became clear. Therefore, it should be 0.
It is desirable to remove serpentinite below 125 mm,
Considering application to an actual machine, 0 to 0.5 mm was set to 30 wt% or less. Moreover, the upper limit of the particle size of the MgO source is 1 to 5 mm.
The reason for this is that coarse grains larger than this cause a large amount of segregation in the lower layer of the actual machine, which may adversely affect the formation of uniform macropores in the layer height direction.

[0017]

[Example] The effect of serpentine grain size on the assimilation behavior of limestone was measured by a tablet test. Table 2 shows the blending ratio of the blended raw materials used in the tablet test.

[0018]

[Table 2]

In FIG. 2, limestone-serpentine-reagent Fe ₂ O ₃
The measurement results of the effect of serpentine grain size on the assimilation of limestone in the system are shown. The assimilation of limestone is remarkably suppressed when a serpentine of 0.125 mm or less is used. Therefore, it is found that it is desirable to remove the fine-grained serpentinite in order to develop the strength of the fired body.

Table 3 shows the blending ratio of the raw materials used for the pot test of φ70 mm, and Table 4 shows the limestone used for the pot test.
The particle size distribution of serpentine is shown.

[0021]

[Table 3]

[0022]

[Table 4]

FIG. 3 shows the product yield, the TI (cold strength, measured by JISM8712), the RDI (reducing powdering property, the pig iron section method), and the JI of the test results of the grain size adjusting pot for limestone and serpentine.
S-RI (JIS reduction rate, JIS M8713) is shown.

In the example, the product yield and TI were improved because the amount of melt generated during the firing process was increased. Further, the firing heat pattern became sharp and the secondary hematite was reduced, so that the RDI was improved. Further, JIS-RI was also improved because the amount of magnetite, which has a poor reducing property, was reduced.

Since it is difficult to remove fine-grained serpentinite in an actual machine, as shown in FIG.
The MgO-containing auxiliary raw material A such as nickel slag and junito is granulated to -1 mm to make a granule having a size of 1 mm or more, and the granulated material is mixed into the sintering raw material and then charged into the sintering machine 4.

[0026]

EFFECTS OF THE INVENTION According to the present invention, the cold strength, reduction powderability and JIS reduction rate of sinter are simultaneously improved.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of an apparatus for carrying out the present invention.

FIG. 2 is a diagram showing the results of measuring the effect of serpentine grain size on the assimilation rate of limestone.

FIG. 3 is a diagram showing a pot test result in which particle sizes of limestone and serpentine are adjusted.

[Explanation of symbols]

 1 Classifier 2 Granulator 3 Granulator 4 Sintering machine A MgO containing raw material B Iron ore C Solid carbon powder D Limestone E Other auxiliary raw material F Return mining

Claims (3)

[Claims] 1. When manufacturing a sinter containing iron ore, the particle size of limestone is adjusted or granulated so that 3 to 5 mm is 15 wt% or more, and the limestone is compounded in a sintering raw material. The particle size of the raw material is 0 to 0.5 mm, 30 wt% or less, 1 to 5 m
It is characterized by adjusting or granulating so that m is 50 wt% or more and blending it into a sintering raw material, then mixing and granulating the entire blended raw material and then firing it with a sintering machine. A method for producing a sintered ore having excellent cold strength. 2. Granulating 1 mm of the MgO-containing auxiliary raw material to 1
The method for producing a sintered ore according to claim 1, wherein the granulated material having a size of at least mm is added to the raw material for sintering, and the high temperature property and the cold strength are excellent. 3. The production of sinter having excellent high-temperature properties and cold strength according to claim 1, wherein one or two of serpentine, nickel slag and dunite is used as the MgO-containing auxiliary material. Method.