JPS6360212A - Smelting reduction method for iron ore - Google Patents

Abstract

PURPOSE:To efficiently execute preheating and pre-reduction by using effectively the high temp. by blowing steam and water into a reaction vessel and flue and adjusting descending speed of iron ore blown under controlling the gas flowing speed ascending the flue. CONSTITUTION:At the time of smelting-reducing the iron ore by using the reaction vessel 11, the steam and water quantities blown into the reaction vessel 11 or the flue 12 from blowing holes 21, 22 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. In this way, the exhaust flowing speed is controlled by adjusting the exhaust gas temp. By this control of exhaust gas flowing speed, the iron ore does not become fluid and falls naturally in the reaction vessel 11. In this way, the utilizing efficiency of exhaust gas is improved and the pre-reduction rate for the iron ore is improved.

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. 1000'C
It needs to be cooled to a certain degree. In addition, in order to form a fluidized bed and obtain a stable flow rate, 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. In order to cool the flue gas and increase the flow rate, a separate gas injection system was required, making the equipment complex. In addition, there was a problem that the upper part of the reaction vessel was overheated due to the flow of high-temperature exhaust gas.

(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 pre-reduce iron ore by effectively utilizing the sensible heat of exhaust gas. It is an object of the present invention to provide a method for melting and reducing iron ore, which can be carried out with simple equipment, and at the same time can prevent overheating of the upper part of a reaction vessel.

(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 upper part of the opening of the reaction vessel, and steam and/or water is blown into the reaction vessel and/or the flue to adjust the temperature of the exhaust gas and rise up the flue. This is a method for melting and reducing iron ore in which preheating and preliminary reduction of the iron ore are controlled by controlling the flow rate of the gas and adjusting the rate of descent 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 coal H 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. 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 by the exhaust gas rising from the reaction vessel during the fall. Furthermore, a gas flow meter 18 and a gas pressure gauge 19 are installed in the flue. Furthermore, a pressure control valve 20 is installed on the outlet side of the dust collector 13.
is attached, and by adjusting this, the pressure of the exhaust gas in the reaction vessel and the flue 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.

Therefore, in the present invention, the exhaust gas temperature is adjusted by adjusting the amount of steam and water blown into the reaction vessel 11 or the flue 12 according to the particle size and specific gravity of the iron ore injected from the iron ore inlet 17. However, by this, the flow rate of the exhaust gas is controlled so that the iron ore naturally falls into the reaction vessel 11 without being in a fluidized state. 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 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 the fluidized region or when fine powdered iron ore is injected, the injection port 21°22
The temperature of the exhaust gas is lowered by increasing the amount of steam and water blown into the exhaust gas, for example, to about 1100° C., and the flow rate of the exhaust gas is lowered. 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 atm in order to increase the utilization efficiency of exhaust gas sensible heat.

(Effects of the Invention) According to the present invention, exhaust gas as high as 1,600 to 1,800° C. can be directly utilized, and heat utilization efficiency can be improved. Moreover, by lowering the flow rate of exhaust gas, fine powdered iron ore can also be used, increasing the types of usable iron ore. Also, since a fluidized bed and exhaust gas cooling system are not required,
Equipment is simplified. Furthermore, if steam or water is blown into the reaction vessel from the top, overheating of this area can be prevented.

(Example) A comparative example will be shown in which preliminary reduction using a conventional fluidized bed and preliminary reduction according to the present invention were performed.

Table 1 Note that 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 increased. It is also found that the preliminary reduction rate of iron ore can be increased, fine iron ore can be used, and the falling yield can be further improved.

[Brief explanation of the drawing]

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. 11... Reaction vessel, 12... Flue, 13... Dust collector, 14... Bottom inlet, 15.16... Side inlet, 17... Iron ore inlet, 18...Gas flow meter,
19... Gas pressure gauge, 20... Pressure control valve, 21.
22... Steam and water inlet Applicant's representative Patent attorney Takehiko Suzue○2. Charcoal material Figure 1 Flow velocity (m7 seconds) Figure 3

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, iron ore is injected from the upper part of the flue installed at the top of the opening of the reaction vessel, and steam and/or water is blown into the reaction vessel and/or the flue to adjust the exhaust gas temperature. A method for melting and reducing iron ore in which preheating and preliminary reduction of iron ore are controlled by controlling the flow rate of exhaust gas and adjusting the natural falling speed of iron ore injected from the upper part of the flue.