JPS6360213A - 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 adjusting oxygen blowing quantity into a reaction vessel and pressure in the reaction vessel and adjusting descending speed of iron ore blown under controlling the gas flowing speed ascending a flue. CONSTITUTION:At the time of smelting-reducing iron ore by using the reaction vessel 11, oxygen and carbonic material quantities blown into the reaction vessel 11 from bottom blowing holes 14 are adjusted in accordance with grain size and specific gravity of the iron ore blown from the iron ore blowing hole 17 installed at the upper part of flue 12. By this adjustment, the exhaust gas flowing speed or exhaust gas pressure is controlled, so that the iron ore drops naturally into the reaction vessel 11. In this way, the high temp. exhaust gas is directly utilized and the utilizing efficiency of heat improved. Further, by decreasing the flowing speed by pressurizing, fine powdery iron ore can be used.

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. In this method of using a fluidized bed, the sensible heat of the high-temperature exhaust gas generated from the reaction vessel is not utilized very effectively. 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 efficiently preheat and preglucose iron ore by effectively utilizing the sensible heat of exhaust gas. An object of the present invention is to provide a method for melting and reducing iron ore, which can be carried out easily and requires simple equipment.

(Means for Solving Technical Problems) The present invention provides a reaction vessel equipped with a mechanism capable of side-blowing or bottom-blowing a gas containing carbonaceous material and oxygen, and storing iron ore pre-reduced in the reaction vessel. In a melt reduction method that reduces and melts iron ore by supplying carbonaceous material and oxygen,
Iron ore is injected from the upper part of the flue attached to the open row L part of the reaction vessel, and the gas rises through the flue by controlling the amount of oxygen blown into the reaction vessel and/or the pressure inside the reaction vessel. This is an iron ore melting and reduction method in which preheating and pre-reduction of the iron ore is adjusted by controlling the flow rate of the iron ore and adjusting the descending speed of the iron ore injected from the upper part of the flue.

(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 inlet 16 to perform secondary combustion of the CO gas generated from the reaction field '511. An iron ore inlet 17 is attached to the upper part of the flue 12, from which the iron ore is allowed to fall naturally into the reaction vessel, and is preheated and prereduced with exhaust gas from the reaction vessel during the fall. 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 and the flue can be adjusted as desired.

However, in the present invention, the exhaust gas flow rate or exhaust gas pressure is adjusted by adjusting the amount of oxygen and carbon material blown into the reaction vessel according to the particle size and specific gravity of the iron ore blown in from the iron ore inlet 17. The iron ore is controlled to naturally fall into the reaction vessel 11. That is, Figure 2 shows the flow rate at the opening of the reaction vessel when the exhaust gas flow velocity is set to 5 m/sec, 4.3 m/sec, and 3 m/sec, and the specific gravity and particle size of iron ore are varied. It shows the change between the falling region and the fluidized region. 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 and gas pressure are detected by the gas flow rate meter 18 and the gas pressure gauge 19, and these detection signals are compared with the relationships shown in these figures. For example, when iron ore is in a fluidized region, the amount of oxygen and carbon material blown may be adjusted to reduce the exhaust gas flow rate, or the pressure control valve 20 may be
to increase the pressure inside the reaction vessel, preferably 3 to 1
0 atm. This allows the iron ore to fall naturally.

(Effects of the Invention) According to the present invention, exhaust gas as high as 1,600 to 1,800° C. can be used directly without being cooled, and heat utilization efficiency can be improved. Moreover, if the flow velocity of the exhaust gas is reduced by pressurization, fine powdered iron ore can also be used, increasing the types of usable iron ore and making more effective use of the sensible heat of the exhaust gas. Furthermore, since a fluidized bed and an exhaust gas cooling system are not required, the equipment is simplified.

(Example) Data obtained by performing preliminary reduction using a conventional fluidized bed and preliminary reduction according to the present invention will be compared and shown below.

Table 1 The method of the present invention has a lower preliminary reduction rate than the conventional method, but this is because the method of the present invention aims to improve heat utilization efficiency, and the reduction is mainly carried out inside the reduction reaction vessel. This is because the system is operated by

Furthermore, the gas flow rate in the conventional method indicates the gas flow rate within the fluidized bed. Based on this data, in the present invention, the gas pressure can be increased for operation, and the gas utilization efficiency can be improved.

[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. DESCRIPTION OF SYMBOLS 11... Reaction container, 12... Flue, 13... Dust collector, ]4... Bottom inlet, 15.16... Side inlet, 17... Iron ore inlet , 18... gas flow meter,
19...Gas pressure gauge, 20...Pressure control valve Patent attorney Takehiko Suzue 02, Charcoal material Fig. 1 Speed (m7 seconds) Fig. 3

Claims (2)

[Claims] (1) Prepare a reaction vessel equipped with a mechanism capable of side-blowing or bottom-blowing gas containing carbonaceous material and oxygen, and supply pre-reduced iron ore, carbonaceous material, and oxygen to this reaction vessel to produce iron ore. In the smelting reduction method for reducing and melting stone, iron ore is blown into the flue installed above the opening of the reaction vessel, and the amount of oxygen blown into the reaction vessel and/or the pressure inside the reaction vessel is controlled. A method for melting and reducing iron ore, in which preheating and preliminary reduction of the iron ore is controlled by controlling the flow rate of the gas rising through the flue and adjusting the natural falling speed of the iron ore injected from the upper part of the flue. . (2) The method for melting and reducing iron ore according to claim 1, wherein the pressure of the exhaust gas is 3 to 10 atm.