JPH05287391A - Treatment of pellet for charging into blast furnace - Google Patents

Abstract

PURPOSE:To provide an effective means, in which an angle of repose in charging pellets can be increased without limiting the grain size of raw material for the pellet and without lowering the production yield and the operational ratio of a blast furnace. CONSTITUTION:By incorporating the green pellet or the burnt pellet of <=80wt.% into the sintering raw material, or using them as bedding ore, the sintered ore 8 and the pellet 6 are fuse-stuck to change the original spherical shape of the pellet. By this method, the pellet having the same angle of repose as the bulky ore and the sintered ore is obtd. and without deviating the distribution of the pellets at the time of charging in the blast furnace, the control can be facilitated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pellet processing method aimed at improving distribution controllability when charging pellets into a blast furnace.

[0002]

2. Description of the Related Art Pellet, sintered ore, and lump ore are available as ore raw materials to be charged into a blast furnace. Among them, pellets have a spherical basic shape and thus have a smaller angle of repose than sintered ore or agglomerated ores and flow into the lower part during blast furnace charging, making it difficult to control the radial distribution of the charge. Become.

Various measures have been proposed as means for increasing the angle of repose of pellets. For example, JP-A-5
No. 1-138513 discloses crushing produced iron ore pellets, and Japanese Laid-Open Patent Publication No. 62-37325 discloses firing raw pellets in an endless moving great type furnace to form agglomerated ore. It is disclosed.

However, in any of the above measures, an extra step is required to adjust the pellet. Further, in the case of a measure for crushing pellets, there is a problem that crushed powder is generated and not only the production yield of pellets is reduced, but also the ventilation in the blast furnace is deteriorated due to the reduction in particle size. In addition, as a countermeasure for pelletizing the pellets by firing agglomeration, the same problem as in the case of crushing described above occurs due to the bursting due to the rapid expansion of the vapor in the raw pellets during drying and firing. In order to avoid the rupture, the fine powder raw material in the pellet raw material ore powder, specifically, the fine powder raw material containing 50 to 80% of the ore having a particle size of 0.044 mm or less, so that the diffusion of vapor in the pellet can be made smooth 30 to 70%
Ore to be used is limited, and
There is a problem that it costs to crush and classify iron ore.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to increase the angle of repose of charged pellets without restricting the grain size of the pellet raw material and without lowering the production yield and operating rate of the blast furnace. The purpose is to provide effective means.

[0006]

According to the present invention, when a sintered ore is manufactured in an endless moving great type firing furnace, raw pellets or fired pellets are mixed in a sintering raw material at a maximum of 80% by weight, and 2 By adding and mixing ~ 5% of powdered granular solid fuel, or by using the combustion pellet as a bed ore with a layer thickness of 10 to 100 mm, the sintered ore is fused to the pellet and the pellet is originally mixed. It is characterized by changing the spherical shape of.

[0007]

When the raw pellets are used to mix the pellets into the sintering raw material, the drying process and the firing process of the pellets can be integrated in an endless moving great type firing furnace. Since there is no restriction on the mixing ratio of the fine powder in the raw material of the raw pellet, naturally,
Easy to cause bursting. However, in the present invention, even if the bursting occurs, the pellet pieces are fused with the sinter to increase the particle size, so that the occurrence of air flow obstruction in the blast furnace due to the particle size reduction can be avoided. Therefore, it is important to sufficiently mix the pellets and the sintering raw material with a mixer so that the pellets are not biased in the sintering raw material. The amount of pellets mixed in is at most 80% by weight in all raw materials. 80% by weight of pellets in sintering material
If it exceeds, it becomes difficult to keep the mixing with the sintering raw material uniform, and pellets without fusion of the sintering raw material come out.

When firing pellets are used to mix the pellets into the sintering raw material, the fuel consumption rate can be improved because the pellets are not fired. When the pellets are mixed in the sintering raw material, the heating and firing of the raw pellets and the heating of the fired pellets result in the addition of 3 to 5% of the weight of the pellets in addition to the powdered solid fuel required for firing the sintering raw material. Appropriate calcination becomes possible by adding powdery solid fuel. If it is less than 3%, unbaked parts and unfused parts are generated, and if it exceeds 5%, the amount of melting of the sintering raw material becomes excessive and there is a problem that air flow is obstructed.

During firing, the mixed pellets bring about the effect of improving ventilation and improve the productivity. The sintering raw material has an average particle size of 2 to
Even when granulated with 3 mm, the air pressure loss is large with about 3 to 5 mm. Further, since the particle size distribution is wide from several tens of μm to several mm, the pressure loss varies due to the segregation of the particle sizes. Since the pellet has a large particle size of about 10 mm and a narrow particle size distribution range, the pressure loss is small and the variation is small, so that ventilation is improved.

By the pellet treatment of the present invention, in which the pellets are mixed in the sintering raw material and fired, the angle of repose of the pellets can be made to be at the same level as other blast furnace raw materials such as raw ore lumps and sintered ores. The distribution of pellets after charging the blast furnace is not biased, and control can be facilitated.

When the pellets are used as a bed ore, it is preferable to use the fired pellets from the viewpoint of avoiding seizure on the grate. Raw pellets should be avoided if they are bursted, as they will clog the grate and deteriorate ventilation.

Since the pellets laid on the pallet as the floor covering are heated by the exhaust gas, in order to heat the pellets, apart from the granular solid fuel required for firing the sintering raw material,
It is not necessary to add the powdered solid fuel. The amount of bedding varies depending on the generation state of the melt of the sintering raw material, but is determined by the depth at which the sintering melt flows into the bedding layer, and the thickness is about 20.
It is preferably from mm to 100 mm. If it is less than 20 mm, the sintered ore will be fused to the grate and it will not be used as a bedding. This is because if it exceeds 100 mm, the melt of the sintering raw material is too thick with respect to the depth at which it flows into the bedding layer.

When the pellets are used as a bed ore, the sintered ore that has been conventionally recirculated as a bed ore can be transported and charged into the blast furnace as it is, so that the productivity is improved accordingly.

By the pelletizing process of the present invention in which the pellets are used as a bed ore and the sinter is fused to the pellets, the angle of repose of the pellets is at the same level as other blast furnace raw materials such as raw ore lumps and sinters. Therefore, the distribution of pellets after charging the blast furnace is not biased, and the control can be facilitated.

The above-mentioned two inventions, a pellet treatment method in which pellets are mixed in a sintering raw material and fired to be fused with a calcined ore, and a pellet treatment method in which the pellets are used as a bedding ore and fused with a combustion ore. Can be performed at the same time and both effects are expressed without offset.

[0016]

EXAMPLE An example in which pellets are mixed with a sintering raw material will be described. As shown in FIG. 1, sinter ore cut out from the floor hopper 1 is laid on a sinter pallet 2, and raw pellets with an average particle size of 10 mm from the raw material hopper 3 are mixed on the weight of 60% by weight. A binder material was charged, and air and gas were introduced in the ignition furnace 4 to ignite and fire. The baked cake was crushed with a crusher 5 to obtain deformed pellets in which sinter ore was fused to spherical pellets.

An example of using the pellets for bedding will be described.
As shown in FIG. 1, bedding floor hopper 1 to sintered pellets 2
Sintered pellets having an average particle size of 10 mm were charged on the top at a ratio of 5% with respect to the sintering raw material to form a bedding with a thickness of 50 mm. Further, a sintering raw material containing 4% of coke was charged from the raw material hopper 3, and air and gas were introduced in the ignition furnace 4 to ignite and fire. The baked cake was crushed with a crusher 5 to obtain deformed pellets in which sinter ore was fused to spherical pellets.

2 (a) and 2 (b) show the sectional shape of the obtained pellets. The sinter 8 was irregularly fused around the pellets 6 or the ruptured pellets 7, and the surface had a roughness similar to that of a normal sinter.

The angle of repose of the treated pellets thus obtained was measured by filling a sample in a 700 × 700 × 700 mm cubic box and discharging the sample from one side of the box.

The experimental results are shown in Table 1.

[0021]

[Table 1] As shown in the table, the angle of repose of the ordinary pellet is 27 °, whereas the angle of repose of the fusion pellet obtained by the method of the present invention increases by 11 °, and It was comparable to that.

[0022]

The present invention has the following effects.

(1) Since pellets can be used as they are, the angle of repose can be increased without lowering the yield of pellet utilization.

(2) When pellets are used as the bedding, the sinter that was conventionally recirculated as the bedding can be transported to the blast furnace as it is, so that the productivity is increased accordingly.

(3) When pellets are used as the bedding, since the packing density in the lower part of the raw material packed bed is smaller than that of the sinter bedding, ventilation is improved and productivity is increased.

(4) When the fired pellets are used, the fuel consumption rate required for firing is reduced.

(5) When raw pellets are used, the drying process and firing process of the pellets can be integrated in an endless moving great type firing furnace.

[Brief description of drawings]

FIG. 1 shows an example of a sintering machine embodying the present invention.

FIG. 2 shows an example of a cross-sectional morphology of a fusion-bonded pellet obtained by the present invention.

[Explanation of symbols]

 1 Bed hopper 2 Sintering pallet 3 Raw material hopper 4 Ignition furnace 5 Crusher 6 Pellets 7 Bursting pellets 8 Fused sinter

Claims (2)

[Claims] 1. A method for treating a pellet for charging a blast furnace, wherein pellets once fired or raw pellets are sintered together with a sintering raw material to fuse the pellets with the sinter and change the pellet shape. 2. A method for treating pellets for blast furnace charging, wherein pellets once fired or green pellets are used as a bedding for sintering to fuse the pellets with the sinter and change the pellet shape.