JPS6360214A - Smelting reduction method for iron ore - Google Patents

Abstract

PURPOSE:To efficiently execute preheating and pre-reduction by using effectively high temp. exhaust gas by blowing iron ores having different grain sizes plural places having different heights and further adjusting the dropping speed of iron ores under controlling the exhaust gas flowing speed by blowing steam and water. CONSTITUTION:The coares grain iron ore is blown into the reaction vessel 11 from the blowing hole 17a fitted to a flue 12 at the high position and the fine grain iron ore is blown from the blowing hole 17b at the low position. Further, the adjusted quantity of steam or water is blown into the reaction vessel 11 and the flue 12,and the exhaust gas flowing quantity is controlled by adjusting the exhaust gas temp., so that the iron ore blown in the reaction vessel 11 drops naturally. In this way, the pre-reduction and preheating of iron ore having large grain size is efficiently executed. Further, as carrier gas is used only for the iron ore having small grain size, this quantity is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention particularly relates to a melt reduction method with an improved preliminary reduction step.

(Prior Art) In a method for pre-reducing iron ore, there is a method of preheating and pre-reducing iron ore by charging iron ore into a fluidized bed in advance. In this method, a fluidized bed is formed using exhaust gas generated from a reaction vessel in which melting and reduction is carried out, but since the temperature of the exhaust gas is 1600 to 1800°C, it cannot be used as is as a gas for a fluidized bed. It is necessary to cool it to about 1000°C. In addition, in order to obtain a flow rate at which a fluidized bed can be formed, it is necessary to increase the flow rate by blowing in another gas. Furthermore, when the particle sizes of iron ores differ, those with small particle sizes have a high reduction rate, but those with large particle sizes have a small reduction rate, resulting in a problem that the reduction rate is non-uniform. In this method of using a fluidized bed, the sensible heat of the high-temperature exhaust gas generated from the reaction vessel is inefficiently utilized, and the reducing ability is not sufficient. Moreover, a separate system for blowing gas was required to cool the exhaust gas and increase the flow velocity, making the equipment complex.

(Technical problem to be solved by the invention) The present invention has been made in view of the above circumstances, and its purpose is to effectively utilize the sensible heat of exhaust gas to inject iron ore with different particle sizes. It is an object of the present invention to provide a method for melting and reducing iron ore, which can efficiently perform preheating and preliminary reduction in each case, and can simplify the equipment.

(Means for Solving Technical Problems) The present invention provides a reaction vessel equipped with a mechanism for side-blowing or bottom-blowing a gas containing carbonaceous material and oxygen, and injecting iron ore which has been pre-reduced into the reaction vessel. In a melt reduction method that reduces and melts iron ore by supplying carbonaceous material and oxygen,
Injecting iron ore with different particle sizes from two or more locations at different heights in the upper part of the flue attached to the upper part of the opening of the reaction vessel, and also blowing steam and/or water into the reaction vessel and/or the flue. Then, the temperature of the exhaust gas is adjusted to control the flow rate of the gas rising through the flue, and the descending speed of the iron ore blown from the upper part of the flue is adjusted to adjust the preheating and preliminary reduction of this iron ore. This is a method for melting and reducing iron ore.

(Detailed description of the invention) The present invention will be explained below with reference to the drawings.

FIG. 1 shows a smelting reduction apparatus for carrying out the method of the present invention, in which a flue 12 is attached to the upper part of the opening of a converter-type reaction vessel 11, and this flue is connected to a dust collector 13. The reaction vessel 11 is equipped with inlets 14, 15, and 16 at the bottom and sides, respectively. Oxygen and carbonaceous material (mainly pulverized coal) are blown into the iron bath in the reaction vessel through the bottom injection port 14, and this injection causes combustion of the carbonaceous material and reduction of iron ore. Oxygen is blown in from the side blowing port 15 to stir the slag, and this stirring transfers the heat of the slag to the iron bath and promotes the reaction between the slag and the iron bath. Oxygen is blown in from another side blow-in port 16 to perform secondary combustion of the CO gas generated from the reaction vessel 11. In the upper part of the flue 12, iron ore inlet ports 17a and 17b are installed at different positions in the height direction. Iron ore with a relatively large particle size is directly charged from the upper iron ore inlet 17a, and iron ore with a relatively small particle size is injected with a carrier gas through the lower iron ore inlet 17b. In the embodiment, two blow-in ports are provided, but it goes without saying that three or more blow-in ports may be provided. The iron ore that naturally falls into the reaction vessel is preheated and pre-reduced by the exhaust gas from the reaction vessel while falling. Furthermore, a gas flow meter 18 and a gas pressure gauge 19 are installed in the flue. Further, a pressure control valve 20 is attached to the outlet side of the dust collector 13, and by adjusting this, the pressure of the exhaust gas in the reaction vessel 11 and the flue 12 can be adjusted as desired. Steam and/or water inlets 21 and 22 are installed at the top of the reaction vessel and at the center of the flue, respectively.

However, in the present invention, the injection position is changed depending on the particle size of the iron ore injected from the iron ore injection port 17. Iron ore with a relatively large particle size is difficult to reduce and preheat, but since it is charged from the top, it has a long residence time in the flue.
The reduction rate can be improved and the preheating temperature can be increased. In this case, the iron ore is supplied from a conventional feeder and no carrier gas is required. On the other hand, iron ore with a relatively small diameter is easily reduced and preheated, so it is injected from a relatively lower part. In this case, the small diameter iron ore is air,
Transported using carrier gas such as recovered exhaust gas. According to this method, iron ore having a large particle size can be efficiently preheated and prereduced. Further, since only fine iron ore is used as carrier gas, the amount of carrier gas used can be reduced. If a steam and/or water inlet is provided between the iron ore inlets 17a and 17b, the flow rate of the exhaust gas can be controlled separately at the upper and lower part of the flue, which also makes it possible to reduce various types of iron ore. This is an effective means of adjusting rates. In addition, in order to adjust the flow rate of the exhaust gas, that is, to allow the iron ore to fall naturally without fluidizing it, the temperature of the exhaust gas is adjusted by adjusting the steam and water blown into the reaction vessel 11 or the flue 12. The exhaust gas flow rate is controlled, and the iron ore flows into the reaction vessel 1.
Let it fall naturally within 1. That is, in Fig. 2, the exhaust gas flow velocity is taken as a parameter, and this is set as 5 m/sec, 4.3 m/7 sec,
3 m/sec, and shows changes in the falling area and fluidized area at the opening of the reaction vessel when the specific gravity and particle size of iron ore are varied. FIG. 3 shows the relationship between the flow rate of exhaust gas and the particle size of iron ore using the specific gravity of iron ore as a parameter. Utilizing such relationships, in the present invention, the gas flow rate is detected by the gas flow meter 18, and this detection signal is compared with the relationships shown in these figures. For example, when iron ore is in a fluidized region or when fine iron ore is injected, the amount of steam and water injected from the inlet 21 and 22 is increased to lower the temperature of the exhaust gas, for example to about 1100°C. As a result, the exhaust gas flow rate is reduced.

This allows the iron ore to fall naturally.

In the present invention, the pressure inside the reaction vessel is preferably increased to 3 to 10 aLm in order to increase the utilization efficiency of exhaust gas sensible heat.

In the present invention, a charging port (23) for lump ore may be provided in the flue, and lump ore, flux, etc. may be separately charged from there.

(Effects of the Invention) According to the present invention, preliminary reduction and preheating can be carried out efficiently for large-grain iron ore, and furthermore, since the carrier gas is used only for small-grain iron ore, the amount used is can be reduced. And 1600℃~1800℃
The extremely high temperature exhaust gas can be used directly, improving heat utilization efficiency. Moreover, by lowering the flow rate of exhaust gas, fine powdered iron ore can also be used, increasing the types of usable iron ore. Furthermore, since a fluidized bed is not required, the equipment is simplified.

(Example) Data will be compared between a comparative example in which iron ore was injected in one stage and the method of the present invention in which iron ore was injected in two stages.

Table 1 From this table, it can be seen that in the present invention, the preliminary reduction rate and preliminary heating are performed well even with large particle sizes, and the amount of carrier gas used is small.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram showing an example of the melting reduction method according to the present invention, and Figure 2 shows changes in the falling area and fluidization area when the particle size and specific gravity of iron ore are changed using the flow rate of exhaust gas as a parameter. FIG. 3 is a diagram showing the relationship between the particle size of iron ore and the flow rate of exhaust gas using the specific gravity of iron ore as a parameter.

Claims (1)

[Claims] Equipped with a reaction vessel equipped with a mechanism that can blow horizontally or vertically a gas containing carbonaceous material and oxygen, and supplying pre-reduced iron ore, carbonaceous material, and oxygen to this reaction vessel to reduce the iron ore. In the smelting reduction method, two pipes of different heights are used in the upper part of the flue attached to the upper part of the opening of the reaction vessel.
In addition to injecting iron ore with different particle sizes from multiple locations, steam and/or water is injected into the reaction vessel and/or flue to adjust the exhaust gas temperature and control the exhaust gas flow rate, and then inject from the upper part of the flue. An iron ore melting and reduction method that adjusts the natural falling speed of the iron ore to adjust the preheating and preliminary reduction of the iron ore.