JPS6328811A - Smelting and reducing method - Google Patents

Abstract

PURPOSE:To improve the thermal efficiency of a smelting and reducing furnace by blowing gas, powder, etc., into a molten slag layer and swiveling the same to cause secondary combustion at the time of using iron ore, reducing agent and auxiliary materials and producing a molten iron in a smelting and reducing reaction furnace. CONSTITUTION:The iron ore, carbonaceous material, slag forming agent, etc., are charged into the reaction furnace of an air furnace type and gases such as oxygen and propane are blown from bottom tuyeres 5 into the furnace and are burned to melt and reduce the iron ore by the heat thereof. The molten iron 2 and molten salt 3 are thereby formed in the furnace. Gases such as O2, N2, CO, CO2 and Ar or powders of CaO, MgO, iron ore, etc., having <=1mm grain size are simultaneously blown into the molten slag layer 3 from nozzles 4 provided at 10-45 deg. angle at the plane cut perpendicularly to the central longitudinal axis of the reaction furnace to swivel the molten slag 3. Oxygen is blown from upper nozzles 6 into the furnace to cause the secondary combustion and the heat thereof is applied to the molten iron, by which the thermal efficiency of the reaction furnace 1 is remarkably improved.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention is directed to the use of secondary combustion heat in a furnace for melting and reduction.
It is about making profits efficiently.

[Conventional technology]

The smelting reduction method using carbonaceous materials is a technology that is already being implemented in various places, and among these technologies, carbon monoxide is secondary combusted into carbon dioxide gas, and the heat generated at that time is transferred to an iron bath. It is known that there are attempts to reduce the amount of carbonaceous materials used.

Furthermore, it is already known to use slag droplets generated by blowing a gas such as nitrogen, carbon dioxide, or argon into the slag layer as a heat medium at this time.

[Problem that the invention seeks to solve]

However, in such conventional methods, as the OD ratio in the system increases, the heat transfer effect to the iron bath after secondary combustion tends to decrease significantly (see behavior by black dots in Figure 3). It is acceptable and not desirable.

Various factors can be cited as causes of this behavior, but the biggest one is that the normal gas blowing method generates a large amount of slag droplets when dealing with extremely viscous slag. One example is that it is difficult.

The OD ratio is the following formula: OD = (CO + H20) / (GO + CO, +
) [, +H, 0).

[Means for solving problems]

The present invention has been developed as a result of various studies to address the conventional problems that require improvements, and has developed a smelting reduction method in which ore is directly reduced using ore, carbonaceous material, and other auxiliary materials. In the smelting reduction method, which directly reduces ore using ore, carbonaceous materials, and other auxiliary materials, gas or gas and powder are blown at high speed into the slag layer generated in the smelting reduction reactor to reduce the slag layer. They have arrived at a smelting reduction method that is characterized by rotating the molten metal around the central vertical axis of the smelting reduction reactor, where secondary combustion occurs and the generated heat is transferred to the molten metal.

[For production]

The present invention was completed after studying the idea of swirling highly viscous slag in a smelting reduction furnace, and the slag is swirled by applying the jetting force of gas directly to the slag. Furthermore, more effectively, instead of relying only on the gas jetting force, gas and powder can be jetted together against the slag, and the slag can be swirled by the powder driven by the gas.

To achieve this purpose, a powder having a particle size of approximately 1 ffIIl or less may be used.

When blowing gas or gas and powder into the slag layer at high speed, in a plane cut perpendicularly to the central vertical axis of the smelting-reduction reactor, blow out the jet nozzles at an angle of 10 to 45 degrees with respect to the central vertical axis. Do this from the nozzle placed in a shifted position.

The idea of the present invention as described above can be embodied in a smelting reduction reactor having the configuration shown in FIGS. 1 and 2.

For example, a smelting-reduction reaction of ore is carried out in a smelting-reduction reactor (hereinafter simply referred to as a reactor) 1, which is basically the same as in a normal case, but in this case, the slag layer existing on the molten iron 2 3, two or more nozzles 4 for blowing gas or gas and powder from the furnace wall of the reactor 1 are provided so that the slag in the furnace swirls.

In addition, in order to contribute to the combustion in the molten iron region 2, a blowing nozzle 5 for introducing oxygen or propane gas is provided at the lower part of the reactor 1, as in the normal case. An oxygen introduction nozzle 6 for performing secondary combustion is provided from the upper furnace wall of No. 1 into the furnace.

In the reactor 1 having such a configuration, ore, carbonaceous material, etc. introduced from the open upper part are fed and combusted by the combustible gas blowing up from the lower part of the reactor 1 in the same way as in normal melting and reduction operations. The molten metal 2 and slag 3 collected at the bottom of the reactor 1 are slag 3. At this time, when gas or ore powder is blown into the carrier gas from the nozzle 4 provided on the furnace wall, the slag 3 is caused by the effect of the jet stream. While the reactor 1
Secondary combustion is caused by oxygen sprayed toward the surface of the slag layer from a nozzle 6 provided on the upper wall of the slag, and the heat generated at this time is used to melt and reduce the newly supplied ore. - Powders used to generate slag turning power include calcium oxide, magnesium oxide, ore, etc.

Further, carrier gases for blowing the powder include oxygen, nitrogen, carbon monoxide, carbon dioxide, and argon.

In this way, by causing secondary combustion while swirling the slag in the reactor 1, combustion heat is effectively transferred and the heat generation effect does not decrease even if the OD ratio increases. Can be done.

〔Example〕

Using a smelting and reducing furnace having a size of 50 mm as shown in FIGS. 1 and 2, ore was smelted and reduced under the conditions shown below.

Amount of carbon material input from the upper part of reactor 1: 25t/hr/,
Iron ore input amount: 52t/hr Oxygen introduction amount from lower blowing port 5: 560ONrrI''harll
Amount of propane introduced: 220 Nrn'/hr Amount of oxygen introduced from nozzle 4: 120ONm/hr/1
Amount of calcium oxide introduced: 2t/hr / Amount of oxygen introduced from one nozzle 6: 520ONm/hr/1
In this case, the behavior was as shown in the graph drawn by the white circles in FIG. 3, and even when the OD ratio was 0.55, the heat storage efficiency increased by about 75%.

Note that the behavior represented by the black circle in FIG. 3 is a typical behavior according to the conventional method.

In addition, in the explanation of this example, the reactor 1 is
Although the introduction of raw materials from above has been described, the method is not limited to this method, and raw materials may be introduced by injection.

〔Effect of the invention〕

By carrying out the method of the present invention, even if the OD ratio increases, unlike the conventional method, the heat storage effect does not decrease, and the effect of secondary combustion can be fully enjoyed.

[Brief explanation of the drawing]

Figure 1 is a side view of the smelting reduction reactor constructed according to the present invention, Figure 2 is a cross-sectional view of the reactor shown in Figure 1, and Figure 3 is a graph showing the heat storage effect↓1. Reactor, 2. Molten iron, 3. Slag, 4. Nozzle for swirling flow, 5. Fuel nozzle for main reaction, 6. Nozzle for introducing oxygen.

Claims (5)

[Claims] (1) In the smelting reduction method in which ore is directly reduced using carbonaceous materials and other auxiliary materials, gas or gas and powder is injected at high speed into the slag layer that is generated in the smelting reduction reactor. A smelting reduction method characterized by rotating the layer around the central vertical axis of a smelting reduction reactor to cause secondary combustion and transmitting the generated heat to the molten metal. (2) High-speed injection of gas or gas and powder into the slag layer from the walls of the smelting-reduction reactor at an angle of 10 to 45° on a plane cut perpendicular to the central vertical axis of the smelting-reduction reactor. The melt reduction method according to claim 1, which is carried out using a nozzle provided. (3) The smelting reduction method according to claim 1 or 2, in which gas or gas and powder are injected at high speed into the slag layer using a plurality of nozzles equidistantly provided. (4) The smelting reduction method according to claim 1, which uses powder selected from calcium oxide, magnesium oxide, and ore. (5) The melt reduction method according to any one of claims 1 to 4, wherein powder having a particle size of about 1 mm or less is used. (5) The smelting reduction method according to claim 1, which uses a gas selected from oxygen, nitrogen, carbon dioxide, carbon monoxide, and argon.