JPH01240627A - Method for sintering iron ore fines - Google Patents

Abstract

PURPOSE:To improve the product yield of sintered ore and coke consumption unit by charging the upper layer of a pallet with a sintering material increased in the component content, also charging the lower layer with a sintering material reduced in the component content and other material, and then carrying out sintering. CONSTITUTION:A sintering material of high Al2O3.MgO content and a sintering material of low Al2O3.MgO content are dividedly placed in a hopper 11 and a hopper 14, respectively. The material reduced in the content of the above component from the hopper 14 is mixed with sinter fines from a sinter-fine hopper 15 in which sinter fines produced in a sintering stage are placed. Subsequently, the resulting mixture is charged into the lower layer on a pallet 1. Further, the material increased in the above component content is charged from the above hopper 11 onto the above lower layer, and then, the upper and the lower layers are sintered.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a method for sintering raw materials for blast furnace charging using a two-layer sintering method, and more specifically, the present invention relates to a method for sintering raw materials for blast furnace charging using a two-layer sintering method. This invention relates to a method for sintering fine iron ore for the purpose of improvement.

[Prior Art] Generally, sintered ore has a high temperature property in which it retains its original shape to some extent up to the lower part of the furnace and melts in the lower part of the furnace, and the melting point and viscosity of the slab are appropriate.
Sintered ore containing gO components is required. Recently, 2 to 3% high MgO has been added to adjust the composition of granulated slag.
1 high, sintered ore containing the 6f2203 component is required.

Conventionally, in order to adjust these MgO1AI2203 components, auxiliary raw materials such as dolomite and serpentine were blended for MgO, and iron ore containing a high β203 component was blended for Al2203.

[Problem that the invention seeks to solve]

In the conventional method, since the component percentages of Al2203 and MgO in the mixed raw materials are high, when sintered as is, the melting point of the slag becomes high in the sintering process, resulting in a decrease in the amount of slag produced during the sintering process. There has been a problem in that the bonding force between particles of the ore decreases, leading to a decrease in the strength and yield of the sintered ore, resulting in an increase in coke consumption and a decrease in productivity.

The present invention solves the above problems. (7)' A Q 203
.

Improves sintering reactivity by changing the MgO abundance state without impairing productivity or coke consumption.

The object of the present invention is to provide a method for sintering fine iron ore that can produce high Al2203, MgO sintered ore.

Means for Solving Problems] The inventors of the present invention have obtained the following findings as a result of intensive research in order to solve the problems. That is, the upper layer of the sintered layer has a high
If raw materials of MgO components are supplied and sintered, most of the surface layer becomes return ore. Moreover, this return ore has already been sintered, although it is insufficient, so if it is mixed into the lower layer and sintered, even if the amount of coke for sintering is the same, it will have a high Aβ2
Since it is only necessary to bond between the return ore particles of 03゜MgO,
High AI easily! 203. Sintered ore of MgO can be obtained.

Based on this basic knowledge, the present invention has developed two
It is designed to be charged in layers.

What is the method of charging raw materials for sintering in two layers?

As disclosed in Japanese Patent Application Laid-Open No. 62-130227,
This is a means used to adjust basicity. In order to improve air permeability and maintain strength, such means charge raw materials with low basicity in the upper layer and raw materials with high basicity in the lower layer.
It is a sintered layer, and the technology for obtaining high Al2203 and MgO sintered ore, which is required when producing blast furnace slag and granulated slag, is in an undeveloped state.

The present invention solves the above-mentioned problems, and is a method for sintering powdered iron ore, in which sintering raw materials are charged and sintered in two layers, upper and lower, on a pallet, and the following technical means are adopted. . That is,
The sintering charge raw materials are high AR203, MgO component raw materials and low A
The upper layer contains high Al22 oa.

The raw material for the MgO component is charged, and the lower layer contains low β203, M
It is characterized in that a mixed raw material of the raw material for the gO component and the return ore from this process is charged and sintered.

[Action 1: In order to make the Ag2O3 and MgO components of the finished sintered ore 1.5% by weight or more, a sintering raw material containing 3% by weight or more of Al2203 and MgO components is loaded on the upper layer of the sintered pallet with a layer thickness of 50 mm or less. The high β203, Mg
This can be achieved by preferentially recovering O sintered ore as return ore and using it again as a raw material for the lower layer. A feature of the present invention is to improve the sintering reactivity by changing the presence state of Ag2O3 and MgO in this way.

On the other hand, if the Al2203 and MgO in the finished sintered ore are too high, it will interfere with blast furnace operation and the quality of granulated slag, so it is necessary to control the Al203 and MgO in the finished sintered ore to 2 to 3%. . Therefore, although it depends on the layer thickness, the upper limit of Al2203 and MgO in the raw material charged to the upper layer is 10%.

Generally, the thickness of the entire sintered layer is about 650 mm, of which 60-70% of the 50 mm below the surface of the upper layer becomes return ore and is recovered because the temperature during firing does not rise sufficiently due to cold air suction. . Furthermore, in this upper layer /1203, M
If a raw material containing 5 to 7% by weight of gO is fired, the strength will decrease and 70 to 90% will be recovered as return ore.

If the thickness exceeds 50 mm, it becomes return ore and is less likely to be recovered, so the thickness should be 50 mm or less.

According to the present invention, high AR203, MgO without thermal loss
Raw materials can be manufactured. This high Aβ203, Mg
By mixing O return ore into the lower layer, Ag2 in the main raw material is
O3 and MgO can be lowered by that much lower than the target components. This means that the lower layer has low Aβ203, MgO
It is only necessary to melt the part and sinter the return ore particles, and the sinterability will be significantly improved.

In advance/'Ml! 203. Sintered ore containing 5% by weight of MgO was experimentally prepared using return ore crushed to 15 mm as raw material, and the other was prepared using only iron ore and auxiliary materials as before, and pot tests were conducted on both. The results are shown in Table 1. As can be seen from Table 1, Aff203. Even though the MgO product components are the same, the coke consumption rate and yield are significantly improved.

Table 1 [Example 1] FIG. 1 shows a flow sheet of a sintering apparatus for fine iron ore in which the present invention can be carried out suitably.

In FIG. 1, bedding ore is charged onto a pallet l from a bedding hopper 2, and on top of it, a lower layer raw material is charged from a lower layer raw material hopper 3 via a drum feeder 4 and a chute 5. The upper layer raw material is charged thereon from the upper layer raw material hopper 6 via the drum feeder 7 and the chute 8.

Coke hopper 9, limestone hopper lO1 and high ε2
03, Each raw material from MgO iron ore hopper 11 is transferred to mixer 1
7 and charged into the upper layer raw material hopper 6. Also,
Coke hopper 12. Limestone hopper 13 and low Aβ2
03, each raw material and return ore 15 from the MgO iron ore hopper 14 are mixed in a mixer 18 and charged into the lower layer raw material hopper 3. The return ore 15 is made by crushing sintered ore with a crusher 19, classifying it with a finished product sieve 16, and charging it into the return ore hopper 15. At this time, the upper layer high AJ2203 after sintering,
Most of the MgO part is recovered in the return ore 15.

The upper layer is charged at an optimal height within a range of 50 mm or less in thickness. Generally, 60 to 70% of the 50 mm portion of the upper layer is recovered as return ore even with the normal sintering method.

Therefore, the key point is how to recover the high Al2O3 and MgO sintered ore in the upper layer as return ore with a high yield, and AR2
03. As a result of investigating the amount of Mg0% and the amount of coke added, it was found that if the amount of coke added was reduced by 20% from the normal amount, 90% of the amount could be recovered as return ore.

Next, an example applied to an actual sintering operation will be explained. Production amount 6
000 ton/day, suction wind i7000Nrn”
/min DL sintering machine using a two-layer charging device as shown in Figure 1, the layer thickness of the upper layer was 45 mm and the layer thickness of the lower layer was 60 mm.
mm, and the operation was carried out with the blended raw material components and coke blending ratio of the upper and lower layers shown in Table 2.

As a result, Table 3 shows a comparison of operation between the method of the present invention and the conventional method. In the method of the present invention, the product components Ag2O3, MgO
It can be seen that even though the values are almost the same, the yield (productivity) and coke consumption rate have been significantly revised.

Table 2 Table 3 [Effect of the invention 1 According to the invention, the yield and the coke consumption rate are significantly improved, resulting in an excellent effect of improving productivity.

[Brief explanation of the drawing]

FIG. 1 is a flow sheet of a fine iron ore sintering apparatus in which the present invention can be suitably implemented. 1... Pallet, 2... Bedding hopper, 3... Hopper for lower layer raw material, 4... Drum feeder, 5... Chute, 6-... Hopper for upper layer raw material, 7... Drum Feeder, 8... Chute, 9... Coke hopper, I
O... Limestone hopper, 11... High Aβ203, M
g O hopper, 12...Coke hopper, 13...
Limestone hopper, 14...low Aβ 20g, MgO hopper, 15...-return hopper, I6... finished product sieve. 17.18-...Mixer, 19...Crusher.

Claims (1)

[Claims] 1. A method for sintering powdered iron ore in which sintering raw materials are charged separately into upper and lower layers on a pallet, in which the raw materials are high Al_2O_3, raw materials with MgO components, and low Al_
Separated into 2O_3 and MgO component raw materials, the upper layer contains high Al
_2O_3, MgO component raw materials are charged, and the lower layer is a low-A
A method for sintering powdered iron ore, which comprises charging and sintering a mixed raw material of l_2O_3 and MgO component raw materials and return ore from the sintering process.