JPS62130229A - Sintering operation method - Google Patents

Abstract

PURPOSE:To prevent the overmelting of a lower layer and to improve the gas permeability by feeding easily meltable and hardly meltable ores onto the pallet of a DL type sintering apparatus to form upper and lower layers, respectively, and by carrying out sintering. CONSTITUTION:In an on-strand cooling or semi-strand cooling system in a DL type sintering apparatus, easily meltable ore having a high degree of melting is fed onto the pallet of the sintering apparatus to form an upper layer, hardly meltable ore having a low degree of melting is fed onto the pallet to form an lower layer. Thus, even when the internal temp. of the upper layer is low, the upper layer is melted and bonded, the overmelting of the lower layer is prevented and the gas permeability is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a sintering operation method for improving air permeability in on-strand cooling or semi-strand cooling systems of DL type sintering machines.

Prior art and its problems In the DL type sintering machine, a method is used in which fine-grain raw materials are charged in the upper layer and coarse-grain raw materials are charged in the lower layer in order to ensure intra-layer air permeability. That is, in normal operation, the above-mentioned particle size segregation ensures intra-layer air permeability and maintains productivity and quality.

However, in on-strand cooling or semi-strand cooling, there is a problem in that excessive heat is generated in the lower layer, which tends to lead to overmelting and deterioration of air permeability, which significantly impedes productivity. This often occurs when there is no large difference in coke distribution between the upper and lower layers. As a countermeasure against this problem, the so-called two-stage charging method has traditionally been adopted, in which raw materials with a high coke blending ratio are distributed in the upper layer, but this increases the density of the raw materials, which worsens air permeability, and increases the coke combustion time, resulting in a decrease in production rate. There was the problem of inviting people.

Purpose of the Invention The present invention was made to solve the above-mentioned conventional problems, and by charging ores with different melting degrees in parts in the height direction of the pallet, over-melting can be avoided in on-strand cooling or semi-strand cooling. The purpose of this study is to propose a sintering operation method that can prevent this and ensure air permeability.

Structure of the Invention The sintering operation method according to the present invention is based on the on-strand cooling or semi-strand cooling method, in which a high-melt ore with a high melting degree is placed in the upper layer of the raw material layer on the sintering machine pallet, and a highly meltable ore is placed in the lower layer. This method is characterized by charging each ore separately.

Here, highly fusible ores and hardly fusible ores are generally CaO
, 5LO2, M2O3, etc., particle size, reaction interfacial area, etc. In other words, brands with a high (easily soluble) melting index calculated by the following formulas (1) to (1-6) are referred to as high-melting ores, and brands with a low (hard-to-melt) melting index are referred to as low-melting ores. It is called.

Q1゛: Meltability index wi for a certain particle size component: Particle size distribution ratio Qi-1 (1-v Δt/ri)' - (1-1
) Δt: Melting retention time (minutes) (time of 7 or more) T: Melting limit temperature, (°C) V: Melting rate (true 7 minutes) ri: Representative diameter of each particle size (tomo) T = 1106 3.19CaO3, 355102+2
1.22 A#203...(1-2)v = 0.0
147 t2-0.09 However, V2O, 05...
(1-3) ε2: High temperature particle porosity (%) et= 100 (IV-d/P) −(
14) V: Volume change ratio d: Apparent density (f; l/d) ρ: True density (ykA) V = 1-0.62ρ (1-m) ... (1
-5) m: Weight change ratio m = 1-r/Zoo -(1-6
)X: Water of crystallization (wt%) (blank below) Table 1 shows representative highly meltable ores and poorly meltable ores classified by meltability index.

If the above-mentioned highly meltable ore is charged into the upper layer of the first sintering machine pallet and the refractory ore is charged into the lower layer, the firing of the upper layer will inevitably be faster and the lower layer will be slower, resulting in overheating. It does not melt and has good air permeability.

FIG. 1 is a schematic diagram showing an example of sintering equipment for carrying out the method of this invention, in which (1) is a refractory ore raw material tank, (2)
is an easily meltable ore raw material tank, (3) (4) is a mixer, (
5) (9) is a surge hopper, (10) is a sintering machine pallet, and (11) is an ignition furnace. That is, when carrying out the method of this invention, 1/3 to 1/2 of the sintering raw material tanks, which are usually around 10 to 15 tanks, are separated into separate systems, one for difficult-to-fusible ores and one for easily-to-fusible ores. It is configured so that it is supplied with

The N meltable ore (11) in the raw material layer (1) is transferred to the mixer (3
), it is cut out from the surge hopper (5) by a roll feeder, transferred and dropped on the deflector plate,
It is classified and loaded onto the sintering machine pallet (10). Similarly, the highly meltable ore (12) in the raw material tank (2) is cut out by a roll feeder from a surge hopper (9) via a mixer (4), and is fed to the NFB on a sintering machine pallet (10).
It is charged on top of the fusible ore (11).

Therefore, in the raw material layer on the pallet, the lower layer is occupied by refractory ore, the upper layer is occupied by highly fusible ore, and furthermore, due to the classification action of the deflector plate, the middle layer is occupied by coarse grains of easily fusible ore and hard to melt ore. It is dominated by a mixture of fine grains of ore.

In this way, when easily soluble heavy ore raw materials are charged into the upper layer and hard to melt ore raw materials are charged into the lower layer, the temperature inside the layer in the upper layer is relatively low due to the cold air sucked after passing through the ignition furnace. The upper layer is sufficiently fused and bonded, and the lower layer does not over-melt and has good air permeability, resulting in faster firing and cooling, and a significant increase in production rate. On the other hand, with crystalline materials, the rotational strength and reduction powdering index hardly change, but the reducibility is significantly improved. This is presumed to be due to the increase in the total number of pores and the large increase in porosity, especially in the lower layer. Note that an increase in pores generally tends to lead to a decrease in rotational strength, but with on-strand and semi-strand cooling methods, the cooling rate is slow and there is no such concern.

Example When a DL type sintering vessel using an on-strand cooling method is charged with the refractory ore and easily fusible ore shown in Table 1 above, the gas temperature pattern in the wind box that is opened during the sintering operation is normally installed. Fig. 2 shows a comparison with the conventional type (conventional example).

Table 2 also shows a comparison of the air permeability index of the firing zone and the cooling zone provided in this example. Roughly speaking, the production rate and quality are shown in Figure 3, and the porosity of the samples according to the pallet height direction is shown in Figure 4.

As is clear from Figure 2 and Table 2, during normal charging, air permeability deteriorates due to overmelting due to excess heat in the lower layer, the firing completion point is delayed, and cooling is delayed due to enlargement of the red tropics. It is clear that the split charging of the present invention speeds up both firing and cooling.

Furthermore, as is clear from FIG. 3, the production rate was significantly improved, and although there was no difference in rotational strength and reduction powdering index, the reducibility was greatly improved. As is clear from Figure 4, during normal charging, the porosity is poor overall, and the air permeability is noticeably deteriorated due to overmelting in the middle and lower layers.
This is presumed to be due to the fact that in the split charging of the present invention, the porosity increases particularly in the lower layer as well as the overall pores increase.

As explained in detail, this invention uses a method of sintering the pallet raw material layer by segregating the easily melting ore in the upper layer and the less melting ore in the lower layer, so it is possible to change the coke ratio etc. Excessive heat (overmelting) in the lower layer in on-strand cooling and semi-strand cooling methods can be prevented without resorting to the above measures, and intra-layer air permeability is greatly improved.

Therefore, according to the method of the present invention, productivity can be greatly improved and products with excellent reducibility can be obtained in terms of quality.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing an example of sintering equipment for implementing the method of this invention, Fig. 2 is a diagram showing a gas temperature pattern in a wind box in an embodiment of the invention, and Fig. 3 is an example of the same as above. FIG. 4 is a diagram showing the porosity of each pallet in the same example in the height direction. DESCRIPTION OF SYMBOLS 1... Difficult to melt ore raw material tank, 2... Easily meltable ore raw material tank, 3, 4... Mixer, 5, 9... Surge hopper, 11... Difficult to melt ore, 12. ...Easily meltable ore. Applicant: Sumitomo Metal Industries, Ltd. Figure 1 Figure 2 Figure 3 Figure 4 Porosity (chi)

Claims (1)

[Claims] In the operating method of a DL type sintering machine, easily melting ore with a high melting degree is charged in the upper layer of the raw material layer on the sintering machine pallet, and refractory ore with a low melting degree is charged separately in the lower layer. A sintering operation method characterized by: