JPH0885829A - Production of sintered ore - Google Patents

Abstract

PURPOSE: To improve the reducibility and strength of a sintered ore and the fluidity of a blast-furnace slag at the time of producing the sintered ore for a blast furnace by specifying the grain size of the auxiliary material contg. the SiO2 and MgO in the raw material and the loading position of the sintered ore on a sintering pallet. CONSTITUTION: The main material such as an iron ore as the raw material for the sintered ore for a blast furnace, a reducing agent such as coke, a slag making agent such as limestone and further serpentine contg. SiO2 and MgO for improving the sinterability of the sintered ore and adjusting the basicity and fluidity of a blast-furnace slag are used, the grain size is controlled so that the serpentine having 10-50mm grain diameter is adjusted to 1.5-6wt.% of the entire sintering material, and the serpentine is placed on a orehearth on a raw material holding mobile pallet as the lowermost layer below the other materials. A sintered ore good in sinterability, capable of excellently reducing the iron oxide in the sintered ore, which is not powdered in a blast furnace and with the fluidity of the blast-furnace slag improved due to the contained SinO2 and MgO is obtained and contributes to the stabilized operation of the blast furnace.

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 capable of adjusting slag basicity in a blast furnace process and adjusting slag fluidity.

[0002]

2. Description of the Related Art In the operation of a blast furnace, adjusting the basicity of the slag in the blast furnace and ensuring the fluidity of the slag are extremely important for smoothly promoting the reaction in the blast furnace. The sintered ore for slag generation in this blast furnace is composed of a main raw material mainly composed of iron ore raw material, and SiO ₂ , MgO such as serpentine.
It is produced by sintering a sintering raw material obtained by mixing and granulating an auxiliary raw material containing limestone, coke and the like. And the above-mentioned SiO
_2. Serpentine rock containing MgO serves as a slag supply source in the blast furnace, and is added to enhance the fluidity of the slag and adjust the sinterability of the sinter.
_2. Raw materials for sinter containing MgO include serpentine, silica stone, peridotite, nickel slag and the like. Further, a raw material containing SiO ₂ and MgO has conventionally been charged into the blast furnace by the method described below. As a raw material for sinter, a powdery auxiliary raw material (powder serpentine, containing SiO ₂ and MgO crushed to an average particle diameter of 2 to 3 mm)
Powdered silica stone, powdered nickel slag, etc.) is mixed with iron ore and sintered before use. Mg having coarse particles with a particle size of 1 to 10 mm of 50 Wt% or more
A method of mixing an O source auxiliary material with iron ore and sintering. (Japanese Patent Laid-Open No. 63-228216) A method of directly charging a lump-like auxiliary material (lump serpentine, lump silica stone, etc.) into a blast furnace from a blast furnace lump ore tank.

[0003]

However, the above-mentioned SiO
₂ , auxiliary materials such as serpentine containing MgO are indispensable for adjusting the basicity in the blast furnace and ensuring the fluidity of the slag, but when used as the above-mentioned sintered ore raw material, It leads to an increase in the amorphous slag phase (glass phase) in the sinter structure and reduces the mechanical strength (falling strength SI) of the sinter. Furthermore, since the powdery MgO component having a large specific surface area is involved in the sintering reaction with the iron component in the sintering raw material, the auxiliary raw material containing MgO produces magnetite with low reducibility, and the sintered product Deteriorates the reducibility of. Further, JP-A-63-228216 discloses a method of reducing the amount of magnetite produced by coarsening the auxiliary raw material for the MgO source to prevent deterioration of the reducibility. But,
This causes deterioration of the mechanical strength of the sinter. Therefore, Mg
The auxiliary raw material for the O source was mixed within the particle size range of other sintering raw materials (10
mm or less), by adjusting the particle size,
It was extremely difficult to improve both reducibility and mechanical strength at the same time.

Further, when the lump is directly charged into the blast furnace in the form of lumps by the above method, the basicity and fluidity of the slag in the blast furnace can be adjusted without affecting the sintering reaction. However, since the massive auxiliary material is used as it is, the adhering moisture and crystallization water in the material are taken into the blast furnace, which lowers the furnace top temperature during blast furnace operation and reduces the amount of dust emission. There were drawbacks such as deterioration of the furnace condition.

The present invention has been made in view of the above circumstances, and SiO ₂ necessary for adjusting the slag component of the blast furnace without deteriorating the reducibility and mechanical strength of the sintered ore.
It is an object of the present invention to provide a method for producing a sinter that can secure a MgO source and / or maintain a blast furnace operation smoothly without lowering the furnace top temperature of the blast furnace.

[0006]

A method according to the above-mentioned object.
The sinter production process described is based on SiO ₂ and / or MgO.
In a method of producing a sintered ore by sintering a sintering raw material containing an auxiliary raw material containing, iron main raw material, limestone and coke,
SiO ₂ and / or Mg having a particle diameter of 10 to 50 mm
The auxiliary raw material containing O is set to 1.5 to 6 Wt% of the sintering raw material and is charged into the lowermost layer portion of the sintering raw material on the sintering pallet. Here, as the auxiliary raw material containing SiO ₂ and / or MgO, raw materials for slag such as silica stone, serpentine, peridotite, and nickel slag can be used. The sintering raw materials other than the auxiliary raw material containing SiO ₂ and / or MgO include iron main raw materials mainly composed of iron ore, returned ore, coke, limestone and quick lime. The lowermost layer portion of the sintering raw material layer on the sintering pallet refers to a lower layer portion of the sintering raw material layer which is immediately above the floor ore laid to hold the sintering raw material layer on the sintering pallet.

[0007]

The method for producing a sintered ore according to claim 1 is
Auxiliary raw material containing O ₂ and / or MgO is 10 to 50 m
It is used by arranging it in the lowermost layer portion of the sintering raw material on the sintering pallet with the composition adjusted to m. That is, the reactivity of the auxiliary raw material itself is lowered by using a massive auxiliary raw material having a particle size of 10 to 50 mm,
Moreover, by arranging the auxiliary raw material in the lowermost layer portion of the sintering pallet, separating it from the other sintering raw materials, and sintering it, the reaction between the two can be suppressed. Therefore, iron ore-
The basic sintering reaction of the limestone system proceeds efficiently, and a large amount of calcium ferrite structure with good reducing properties is generated,
Furthermore, since the amorphous slag phase (glass phase) is reduced, the effect of improving the reducibility, yield, and mechanical strength of the sintered ore is exerted. At this time, SiO ₂ and / or Mg
If the particle size of the auxiliary material containing O is smaller than 10 mm, the particle size is within the same particle size range (10 mm or less) as that of the other sintering materials. It becomes easy to mix with the binder material and easily forms a brittle amorphous slag phase (glass phase) as a binder phase even after the sintering reaction, thereby lowering the mechanical strength of the sintered ore. In order to improve such a decrease in strength, high temperature firing is necessary, and as a result, the amount of magnetite produced increases and the reducibility decreases. Therefore, coarsening the auxiliary raw material within the grain size range of 10 mm or less cannot be a fundamental solution to the strength reduction.

If the particle size of the auxiliary material containing SiO ₂ and / or MgO exceeds 50 mm, the strength, yield, and
The reducibility is further improved, which is preferable, but it is difficult to uniformly disperse the particles in the furnace at the time of charging the blast furnace.
The upper limit is 0 mm. Said SiO ₂ and / or M
If the amount of the auxiliary raw material containing gO is less than 1.5 Wt% of the entire raw material of the sintered ore, the amount of slag produced in the blast furnace is too small and the effect of adjusting the slag amount is small. Further, even if the amount exceeds 6 Wt%, the effect of the increase does not appear, and the raw material cost is relatively high, which is not economical. When the sinter ore obtained by the method for producing a sinter according to claim 1 is used, the adhering water and crystal water in the auxiliary raw material are removed in advance during the sintering process. Even when charged into the blast furnace, the furnace top temperature is not lowered, and stable blast furnace operation can be maintained.

That is, the present invention relates to SiO ₂ and / or Mg
Since the reducibility can be improved and the generation of the amorphous slag phase can be suppressed by efficiently suppressing the reaction between the auxiliary raw material containing O and the other sintering raw material, the above-mentioned JP-A The coarsening of the auxiliary raw material for the MgO source (the ratio of the particles having a particle size of 1 to 10 mm is 50 Wt% or more) as in Japanese Patent Laid-Open No. 63-228216 causes deterioration of the mechanical strength (SI), which is a problem. Never.

[0010]

Embodiments of the present invention will now be described with reference to the accompanying drawings to provide an understanding of the present invention.
Table 1 is a table showing the particle size distribution of serpentine to which the manufacturing method of the example of the present invention and the conventional example (sintered ore using powder serpentine and silica powder) is applied. Further, FIG. 1 is a diagram showing the relationship between the furnace top temperature and the amount of increase in water content brought into the blast furnace. As shown in Table 1, the average particle size of the powder serpentine is 1.87 mm.
And the ratio of particles of 10 mm or less to the whole is 10
Although it is 0 Wt%, in this embodiment, the particle size is 10 to 50.
A lump serpentine with an average particle size of 17.0 mm in which the proportion of mm particles is adjusted to 90 Wt% or more of all serpentine is used. The silica stones have almost the same grain size composition, and the powder silica stones have an average particle diameter of 1.91 mm and the agglomerate silica stones have an average particle diameter of 17.5 mm. Table 2 shows the mixing ratio and basicity (C / S) of the auxiliary raw material containing SiO ₂ and MgO in the sintering raw material.

[0011]

[Table 1]

[0012]

[Table 2]

In the present example and the conventional example, a fine quartz powder having a fine grain size shown in Table 1 and a massive serpentine having a grain size of 10 to 50 mm, and a silica powder having a similar grain size composition were used. By changing the mixing ratio of the agglomerated silica as shown in Table 2, the reduction rate (RI), yield, mechanical strength (S) of the sintered ore
I) and the reduction dusting rate (RDI) were measured. Table 2 below
Will be described in detail. The raw material composition of the entire sintering raw material on the sintering pallet is shown in A, and SiO ₂ and / or MgO having a particle diameter of 10 to 50 mm arranged in layers on the upper surface of the sintering pallet.
B is the average particle size and blending ratio of the auxiliary raw material containing C, and C is the composition of the residual raw material charged in the upper layer of the residual auxiliary raw material.
Is shown in. Here, the blending ratio of each raw material in B and C is a value expressed as 100 Wt% of the whole sintering raw material A on the sintering pallet. In Example 1, on the sintering pallet on which the bed ore for holding the sintering raw material is arranged,
The agglomerate serpentinite having the particle size distribution shown in Table 1 was laid with a belt feeder or the like so as to be 1.88 Wt% of the total sintering raw material to be charged, and as a lowermost layer (B), further on top of that, Table 2
The sintering raw material (C), which is the uppermost layer than the lowermost layer of the raw material composition shown in Example 1 above, is placed, and the sintering raw material is loaded using a DL type sintering machine having an effective machine length of 120 m and a sintering pallet width of 5 m. 2. Layer thickness 500 mm, firing temperature about 1360 ° C, pallet speed 3.
The sintering raw material (A) was processed under a sintering condition of 4 to 3.6 m / min. The reducibility of the sinter thus obtained is 7
5.9%, reduction powderability 35.0%, mechanical strength 8
The yield was 7.0% and the yield was 82.93%. Here, the mechanical strength (SI) is expressed as a ratio of particles that remain without being broken when a sinter having a predetermined particle size is dropped freely from a predetermined height onto an iron plate. ) Indicates the ratio of the sinter reduced by heating the obtained sinter in a predetermined reducing atmosphere. In addition, reduction powderability (RD
In I), the obtained sinter is subjected to reduction treatment under predetermined conditions, and the sinter ore is pulverized.

In the following Example 2, sinter pallets in which the bed ore is also placed are charged with the agglomerate serpentine having the particle size distribution shown in Table 1 and the agglomerate silica having an average particle size of 19.4 mm. 2.60 Wt% and 0.34 Wt% for all sintering materials
As a result, a sintering raw material (C), which is a lowermost layer portion (B) laid by a belt feeder or the like, is formed on the uppermost portion of the raw material constitution shown in Example 2 of Table 2 above.
And the sintering raw material (A) under the same sintering conditions as in Example 1.
Was processed. The sinter obtained in this manner had a reducibility of 78.2%, a reduction pulverizability of 34.6%, a mechanical strength of 88.20%, and a yield of 84.10%. It was In Example 3, a belt feeder was also used so that lump serpentine with an average particle diameter of 23.0 mm was 4.8 wt% with respect to all the sintering raw materials to be charged on the sintering pallet on which the bedding ore was placed. As a result, the sintering raw material (C), which is the uppermost layer than the lowermost layer portion of the raw material composition shown in Example 3 of Table 2, is arranged as the bottommost layer portion (B) of the flooring, and the same firing as in Example 1 is performed. The sintering raw material (A) was processed under the binding conditions. The sinter thus obtained had a reducibility of 78.6%, a reduction pulverization property of 34.7%, a mechanical strength of 88.3% and a yield of 8%.
It was 4.3%. In the conventional example shown in Table 2, the raw material having no lump serpentine and lump silica was used and treated under the same sintering conditions as in Examples 1 to 3. With respect to the obtained sinter, the reducibility is 71.9%, the reduction pulverization property is 35.7%, the mechanical strength is 85.58%, and the yield is 79.
It is 89%, and it can be understood that Examples 1 to 3 are superior in any numerical value. In the present embodiment, a reducible rate of 74 Wt% or more can be achieved, and the reduction powderability (RD
It can be seen that I) does not cause any problems. In addition, in the above-mentioned Example and the prior art example, the result of performing the processing with the basicity (C / S) being constant at 1.75 is shown.

FIG. 1 is a diagram showing the relationship between the furnace top temperature and the amount of increase in water content brought into the blast furnace. Here, the furnace top temperature on the vertical axis is displayed with the base temperature appropriately determined in normal operation or the like as the base point, and the horizontal axis shows the increase in water content brought into the furnace. The figure shows that the furnace top temperature decreases by about 11.8 ° C. each time the amount of water per charge increases by 1 ton. As shown in the chemical formula (3MgO · 2SiO ₂ · 2H ₂ O), serpentine contains 13 Wt% of water of crystallization, and when the attached water content of the lumpy material is about 2 Wt%, the total water content is About 15 Wt%, 2 ton / ch of such serpentine
Assuming that the water content is used at a rate of 0.3 ton / ch, the temperature drop at the top of the furnace is about 3.5 ° C. from FIG. Due to this temperature decrease, the amount of dust (gas ash) discharged from the blast furnace is reduced and the dust is accumulated in the blast furnace, which hinders the operation of the blast furnace. However, by releasing the water of crystallization and the attached water on the sinter pallet in advance, the water content in the blast furnace is reduced and the furnace top temperature is increased to prevent aeration of air due to dust accumulation in the blast furnace. Blast furnace operating conditions can be greatly improved by eliminating trouble factors. Further, in the above embodiment, SiO
₂ , examples of serpentine and silica stone were shown as auxiliary raw materials containing MgO, but other raw materials such as peridotite and nickel slag are also made into a lump of 10 to 50 mm and 1.5 to 6 Wt in the sintered ore.
The above-mentioned effect can be exhibited by blending at least%.

[0016]

According to the method for producing a sintered ore according to claim 1, SiO ₂ and / or M having a particle diameter of 10 to 50 mm.
The auxiliary raw material containing gO is mixed in the sintering raw material as 1.5 to 6 Wt%, and it is placed in the lowermost layer portion on the sintering pallet and sintered, so that it is different from other sintering raw materials. By suppressing the reaction, the reducibility of the sinter can be improved and the yield and strength are improved.
In addition, the amount of SiO ₂ necessary for adjusting the slag component of the blast furnace,
It is possible to secure MgO and to smoothly maintain the operation of the blast furnace without lowering the furnace top temperature of the blast furnace. further,
In order to suppress the reaction with other sintering raw materials, the excellent effect that the basic sintering reaction of the iron ore-limestone system is efficiently realized can be achieved.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between a furnace top temperature and an increase amount of water introduced into a blast furnace.

Claims (1)

[Claims] 1. A method for producing a sintered ore by sintering a sintering raw material containing an auxiliary raw material containing SiO ₂ and / or MgO, a main iron raw material, limestone and coke, and having a particle diameter of 1
The auxiliary raw material containing 0 to 50 mm of SiO ₂ and / or MgO is charged to the lowermost layer portion of the sintering raw material on the sintering pallet as 1.5 to 6 wt% of the sintering raw material. Method for producing sintered ore.