JPH07331344A - Method for controlling permeable gas in exhaust gas circulated sintering - Google Patents

Abstract

PURPOSE:To improve the gas permeability in a sintering layer and to improve the yield and the productivity of sintered ore by blending difficult-to-melting ore in sintering raw material in an exhaust gas-circulated permeable gas control. CONSTITUTION:In the permeable gas control method in the exhaust gas circulated sintering, by which the exhaust gas exhausted from a sintering machine is again returned back to a sintering bed to reuse this exhaust gas as the heat source for sintering the sintering raw material, the difficult-to-melting ore, such as qualtz series ore, etc., is blended at 20-50% in the sintering raw material. In the combustion part in the ordinary main raw material grain, the surface of the main raw material grain is melted by the combustion heat and becomes the condition of combining the adjacent main raw material grains and the permeability around these grains is lowered. Therefore, as the blended difficult- to-melted ore is difficult to melt by the combustion heat, the combination between the grains is cut off at the part of the difficult-to-melted ore and the gas permeability of the sintering layer is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas circulation sintering aeration control method, and more particularly to a method for improving the air permeability of a sintered layer to reduce the thickness of the lower red tropical zone. The present invention relates to an exhaust gas circulation sintering aeration control method capable of improving the yield and productivity of ore.

[0002]

2. Description of the Related Art For example, as described in Japanese Unexamined Patent Publication (Kokai) No. 54-104403, "Manufacturing Method of Sintered Ore", in a Dwightroid type sintering machine which is a general continuous sintering machine, The coke charged with the sintering raw material on the sintering bed has a grain size of 0.5 to 3 mm. The average particle size is described in JP-A No. 54-129003, “Method for producing small spherical coke” and JP-A No. 53-37.
It is usually 1 to 2 mm as described in "NOx Suppressing Sintering Method" in Japanese Patent Laid-Open No. 103. Further, as another continuous sintering method, the exhaust gas discharged from the sintering machine is again
An exhaust gas circulation sintering method of returning to a sintering bed for reuse is known.

[0003]

In this exhaust gas circulation sintering method, since the exhaust gas at a high temperature of 100 to 300 degrees is returned to the sintering bed, the ventilation resistance in the layer on the sintering bed is large,
The amount of passing air will decrease. In addition, since the exhaust gas is at a high temperature, the cooling of the sintered layer on the sintering bed is delayed,
The thickness of the red tropics, especially in the lower red tropics, which is a fusion zone of 0 degrees or more and whose pressure loss is about twice that of other raw material layers and sintered layers (see the graph in Fig. 4), increases the raw material. There is a problem in that the air permeability of the entire layer on the sintering bed during combustion is reduced, and the yield and productivity are reduced.

Actually, when the sintering work is performed using the powdery coke having the average particle size of 1 to 2 mm, it takes 6 to 7 minutes until one powdery coke completely burns, and it takes about 6 to 7 minutes in the latter stage of combustion. The thickness of the lower red tropics increased to almost 150 mm, compared to an average of 100 mm in the Dwightroid equation, which reduces the air permeability of the entire layer on the sintering bed. Therefore, if the feed rate of the sintering bed is constant, the sintered ore will be discharged incompletely fired and the yield will deteriorate,
Further, if the feed rate of the sintering bed is slowed down to secure the yield of a certain standard, the productivity will decrease. Therefore, the present inventor has focused on difficult-to-melt ores such as Riodoce (trade name), which has been conventionally mixed in the combustion raw material in an amount of only about 10%, and increases the amount of the hard-to-melt ores to perform sintering. It came to develop a method of adjusting the air permeability of a layer.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide an exhaust gas circulation sintering aeration control method capable of improving the air permeability of a sintered layer to improve the yield and productivity of the sintered ore. To aim.

[0006]

A method according to the above-mentioned object.
Exhaust gas circulation sintering ventilation control method described, the exhaust gas discharged from the sintering machine, again, in the ventilation control method of exhaust gas circulation sintering to return to the sintering bed and reuse as a heat source for sintering the sintering raw material , 20 to 5 refractory ore in the sintering raw material
It is configured to be blended with 0%. The refractory ore referred to here is, for example, quartz-based ore such as Riodose, MBR, and Yampy (above, trade name). Further, as the quartz-based ore, SiO ₂ is 0.3 to 5.5%, Al ₂
O ₃ is 2% or less, water of crystallization is 2% or less, and it is dense and hardly melts.

[0007]

In the exhaust gas circulation sintering aeration control method according to the first aspect, when 20 to 50% of the refractory ore is mixed in the sintering raw material and the sintering is performed, in the burning portion of the usual main raw material grains. , The surface of the main raw material grains is melted by the heat of combustion, and the adjacent main raw material grains are bonded to each other, and the air permeability in the periphery is reduced, but the refractory ore to be blended is difficult to melt due to the combustion heat. The grain-to-grain bonds are cut off at the portion of the difficult-to-melt ore, the air permeability of the sintered layer is improved, and the yield or productivity of the sintered ore is improved.

[0008]

Embodiments of the present invention will now be described with reference to the accompanying drawings to provide an understanding of the present invention. Here, FIG. 1 is an explanatory view showing the progress of sintering by an exhaust gas circulation sintering aeration control method according to an embodiment of the present invention,
FIG. 2 is a graph showing the relationship between the amount of Riodoce mixed with the thickness of the lower red tropical zone, and FIG. 3 is a graph showing the relationship between sintering time and product yield with respect to the compounded amount of Riodoce.

The exhaust gas circulation sintering ventilation control method according to an embodiment of the present invention is an exhaust gas circulation sintering method in which exhaust gas discharged from a sintering machine through a main duct is returned to a sintering bed by a blower and reused. This is a ventilation control method. On the sintering bed, the sintering raw material mixed with coke is charged from the charging hopper and ignited at the upper part of the raw material layer in the ignition furnace of the sintering machine. Gradually descends to the lower layer (see FIG. 1), and the combustion ends by the time it is discharged from the sintering machine. After that, the produced sinter is crushed by the primary crusher and cooled in the cooler.

The characteristic feature of the exhaust gas circulation sintering aeration control method of the present invention is that the gas permeability of the sintered layer is improved by adding a refractory ore to the sintering raw material, and as a result, a sintered ore product is obtained. It is the point that the yield and productivity have been improved. As the refractory ore, it is possible to use, for example, quartz-based ores with a melting temperature of 1250 to 1330 degrees, such as Riodose, MBR, and Yampy. The ratio of the refractory ore mixed in the sintering raw material is
20 to 50%, especially 30 to 45% is preferable. If the blending ratio of the refractory ore is less than 20%, the air permeability of the sintered layer becomes poor and the lower red tropical zone becomes thicker (see FIG. 2), which results in longer sintering time and lower productivity. Also, 5
If it exceeds 0%, the sintering time does not change, but the ratio of the refractory ore that is not desired to be contained in the sintered ore increases, so the product yield decreases (see FIG. 3).

As shown in the graph of FIG. 3, when the refractory ore is mixed in the sintering raw material in an amount of 20 to 50%, a high product yield of about 83 to 84% is maintained during combustion.
The sintering time can be shortened to about 35 to 36 minutes, and as a result, as shown in FIG.
0 mm (10% of the amount of riodose) was 100
It becomes thin to about mm.

The main raw material grains of the sintering raw material are melted on the surface of the grains due to the combustion heat in the red tropical zone at a high temperature of 1100 degrees
The adjacent main raw material grains are bonded together. Therefore, the gaps between the grains are closed, and the air permeability in the periphery is reduced.
On the other hand, since the refractory ore is difficult to melt due to combustion heat, the bonds between the grains are cut off at the refractory ore portion, and the air permeability of the sintered layer is improved at this portion. As a result, the lower red tropical zone becomes thin, the sintering time of the raw material layer is shortened, and in the past, since the lower red tropical zone was thick, the sintered ore was discharged as incompletely fired, resulting in poor yield. In the present invention, since the sintering raw material is completely fired during the predetermined feeding time of the sintering bed, the yield is improved. Further, in the past, since there is a high possibility that the sintered ore will be discharged as it is incompletely fired, it was difficult to increase the feed rate of the sintering bed, but in the present invention, the burning rate of the raw material layer is increased. Therefore, even if the feeding speed of the sintering bed is increased, it is possible to sufficiently cope with it, and thus the productivity of the sintered ore can be improved.

Hereinafter, referring to Table 1, a specific comparison will be made between a sintering example by the exhaust gas circulation sintering and ventilation control method of the present invention and a sintering example by the conventional exhaust gas circulation sintering and ventilation control method. To do.

[0014]

[Table 1]

As is clear from Table 1, when 20% or 45% of refractory ore is mixed in the sintering raw material, the thickness of the lower red tropical zone is reduced to almost two-thirds that of the conventional method.
The productivity by the conventional method was 31.0T / D · m ² is Example 1, 34T / D · m ^2, in Example 2 35
Approximately 10% improvement in T / D · m ² and product yield
It was 84.0% in the conventional method, but was 8 in Example 1.
It was improved to 4.5% and to 84.3% in Example 2.

[0016]

According to the exhaust gas circulation sintering ventilation control method of the first aspect of the present invention, 20 to 5 refractory ores are contained in the sintering raw material.
Since the content of 0% is mixed, the air permeability of the sintered layer is improved, which reduces the thickness of the lower red tropical zone, shortens the sintering time, and improves the yield and productivity of the sintered ore. .

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing the progress of sintering by an exhaust gas circulation sintering aeration control method according to an embodiment of the present invention.

FIG. 2 is a graph showing the relationship between the amount of Riodoce and the thickness of the lower red tropical zone.

FIG. 3 is a graph showing the relationship between the sintering time and the product yield with respect to the blending amount of riodose.

FIG. 4 is a graph showing the pressure loss of each layer on the sintering bed during raw material combustion.

Claims (1)

[Claims] 1. The exhaust gas discharged from the sintering machine,
In the ventilation control method of exhaust gas circulation sintering, which is returned to the sintering bed and reused as a heat source for sintering the sintering raw material, 20 to 50% of refractory ore is mixed in the sintering raw material. Exhaust gas circulation sintering ventilation control method.