JPH01195213A - Method for supplying raw powdery material into iron bath type melting and reducing furnace - Google Patents

Abstract

PURPOSE:To accelerate a reaction by blowing a raw material into the melt in a reaction vessel in a specified direction with the use of a carrier gas, and swirling the molten iron bath. CONSTITUTION:Iron oxide as the raw material and a carbonaceous material are added to the melt consisting of molten iron 2 and molten slag 3 in the reaction vessel 1; oxygen is blown in from the top to reduce the iron oxide to obtain molten iron 2. In this case, a blowing nozzle 5 set at an angle theta of 15-60 deg. to the line connecting the nozzle outlet and the center O of the molten iron bath is provided. The raw material powder is blown in from the nozzle 5 along with a carrier gas to swirl the molten iron bath.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method of operating an iron bath type smelting reduction furnace for reducing iron oxide to molten iron.

[Prior Art] As a method of producing molten iron by reducing iron oxide in a smelting reduction furnace, a reaction vessel capable of upward blowing with oxygen is used.

A method of top-blowing acid is carried out while iron oxide and lump coal are introduced into a molten material consisting of molten iron and molten slag in the reaction vessel from the upper part of the reaction vessel.

However, this method has a problem in that since the specific gravity of coal is low, the coal floats to the surface of the slag in the reaction vessel and is blown near the furnace wall, for example, resulting in low utilization efficiency. JP-A-59-153819 discloses a method using this lumpy carbonaceous material, in which the top-blown oxygen is blown in a direction shifted from the direction toward the center of the slag bath, causing the slag bath to swirl and flow. This method effectively burns the carbonaceous material blown near the wall using top-blown oxygen. Therefore, this method is a method of burning carbonaceous materials, not a method of dissolving carbonaceous materials into molten iron. In addition, in this method, because the direction of the top-blown oxygen is shifted, the position where the blown oxygen flow contacts the bath is shifted from the bath center and is closer to the furnace wall, causing overheating of the furnace wall and causing serious damage to the furnace. Become.

In iron oxide smelting and reduction furnaces, operations are also carried out in which carbonaceous powder or iron oxide powder is supplied to molten iron through a blowing nozzle using a carrier gas. FIG. 2 is a diagram showing a conventional method of supplying carbonaceous powder or iron oxide powder (carbonaceous powder or iron oxide powder is abbreviated as powdered raw material in this specification) to molten iron. (A
), the powdered raw material is blown into the molten iron 2 using a carrier gas from the blowing nozzle 10 provided at the bottom of the reaction vessel, and acid is blown from the top blowing lance 4. The blown raw material powder (particularly because the carbonaceous powder is lighter than the molten iron) floats in the molten iron 2 and reaches the slag 3. However, in this method, the powdered raw material only passes through the molten iron layer, and the residence time of the powdered raw material in the molten iron is short, which is insufficient for it to dissolve or react in the molten iron.
Since it reaches slag 3 in a short time, the reactivity of the powdered raw material is low. In (B), the powdered raw material is blown into the molten iron 2 using a carrier gas from the blowing nozzle 11 provided on the furnace wall of the molten metal sump of the reaction vessel.

At this time, one or more blowing nozzles 11 are provided in the direction toward the center 0 of the molten iron bath. However, even in this method, the powdered raw material only passes through the molten iron, and the residence time of the powdered raw material in the molten iron is insufficient for it to be dissolved in the molten iron or reacted in the molten iron.

[Problems to be Solved by the Invention] The object of the present invention is to promote the dissolution of a powdered raw material injected into molten iron into the molten iron and the reaction in the molten iron. Furthermore, in an iron bath type smelting reduction furnace, it is important to promote the reaction at the interface between the molten slab and molten iron, so the present invention aims to further promote the contact between the molten slag and molten iron.

[Means for Solving the Problems] The present invention involves adding iron oxide and carbonaceous material to a molten material consisting of molten iron and molten slag in a reaction vessel capable of top-blowing oxygen, and then top-blowing acid to reduce the iron oxide. In an iron bath-type smelting reduction furnace that produces molten iron, when blowing powdered raw materials into molten iron, the powdered raw materials are blown into the molten iron using a carrier gas in a direction 15° to 60° away from the direction toward the center of the molten iron bath. This is a method for supplying powdered raw materials to an iron bath type smelting reduction furnace, which is characterized by blowing from one or more blowing nozzles to cause a molten iron bath to swirl and flow.

FIG. 1 is a diagram showing an example of an iron bath type smelting reduction furnace in which the present invention is carried out.The reaction vessel 1 is in the form of a converter lined with a refractory material, and the furnace wall of the pool of molten iron 2 is It has a blowing nozzle 5 for blowing powdered raw material. The powdered raw material is blown from this blowing nozzle 5 in a direction 15'' to 60'' shifted from the direction toward the center 0 of the molten iron bath using a carrier gas.

FIG. 1 CB) is a YY sectional view of FIG. 1(A). In Fig. 1(B), the powdered raw material is blown in the direction of arrow 6,
The direction of arrow 6 is a direction shifted by 0 degrees from the direction toward the center O of the iron bath, and in the present invention, 200 is 15 to 60 degrees. If θ is less than 15°, it is difficult to generate swirling flow in the molten iron bath, and if θ exceeds 60″, the furnace wall of the reaction vessel will be damaged.
Although the figure shows an example in which there are two blowing nozzles 5, the number of blowing nozzles 5 may be one or two or more. For example, an example in which there are six blowing nozzles 5 is shown in FIG. In the example shown in Fig. 3, when the two reaction vessels 1 are turned over and the hot metal 2 and slag 3 are discharged, the blowing nozzle 5 is exposed on the slag surface and is shifted by 20 degrees from the direction toward the center O. Space the nozzles evenly.

In this iron bath type smelting reduction furnace, iron oxide, such as iron ore, and carbon material, such as coal, are added to a molten material in a reaction vessel consisting of molten iron 2 and molten slag 3, and the mixture is top-blown acid with a lance 8.
Iron oxide is exposed to iron to increase the amount of molten iron 2, and when a predetermined amount of molten iron is reached, the molten iron is tapped, and the tapped molten iron is decarburized and refined, for example, in a separately provided steelmaking furnace. The first molten iron or molten slag can be obtained, for example, by not tapping the entire amount of molten iron or molten slag during the previous tapping, but leaving a portion of the molten iron or molten slag remaining in the reaction vessel.

In the present invention, powdered raw materials are injected into the molten iron, but iron oxide and carbonaceous materials are also supplied in conjunction with the injection of the powdered raw materials into the molten iron.For example, iron ore or coal lumps are reacted from the upper part of the reaction vessel. It may also be added to the melt in the container.

As a powdery raw material, one having a particle size of 1 mar or less can be easily blown into the material, and an inert gas such as N2 gas is suitable as a carrier gas.

[Function] In the present invention, as shown in FIG. 1(B), the powdery raw material has an angle of θ
Since the carrier gas is blown into the molten iron bath in a direction shifted by 0, a swirling flow as shown by the arrow 7 is generated in the molten iron bath. This swirling flow of the molten iron bath is accompanied by the following effects. That is, the powdered raw material is involved in the swirling flow, the residence time in the molten iron becomes longer, and the mixing contact with the molten iron is strengthened, so that dissolution in the molten iron and reaction in the molten iron are promoted.

The molten iron that has been stagnant near the furnace wall of the reaction vessel is drawn into the swirling flow and comes into active contact with the powdered raw material, further promoting the dissolution of the powdered raw material into the molten iron and the reaction in the molten iron.

In FIG. 1(A), upward and downward flows 9 are generated in the molten slag 3 due to the top-blown acid. According to the present invention, a swirling flow 7 is generated in the molten iron that crosses the vertical flow of the molten slag. Therefore, the interface between the molten iron and molten slag is actively stirred by the upper and lower flows 9 and the swirling flow 7, and the reaction between the molten iron and molten slag also proceeds actively. If the oxygen blowing direction is shifted when blowing oxygen into the reaction vessel, the furnace wall will be overheated and the furnace will be easily damaged as described above, but in the present invention, the powdery raw material is blown using an inert gas. Therefore, even if the blowing direction is shifted, the furnace wall will not be overheated.

[Example] In the reaction vessel shown in Fig. 1, 3.5 tons of hot metal (C: 3.5%) and slag (Cab/5in2: 1.2%) were placed.
MgO: 15%.

AQ20. :15%) was charged, top blowing lance: 46ON m3/H, bottom blowing nozzle: 23ON m'/
Acid was blown with H.

At this time, from each of the two nozzles (set at an angle of 20° from the direction toward the center Q) provided on the side of the reaction vessel,
Coal powder of 13.5 kg/min or less and iron ore powder of 1
After blowing at a feed rate of 5.4 kg/min for 1 hour,
Approximately 8.4 tons of hot metal was produced. This was an approximately 10% improvement in productivity compared to normal bottom blowing.

[Effects of the Invention] The present invention promotes the dissolution of powdered raw materials into molten iron and the reaction in molten iron, as well as the reaction at the interface between molten slag and molten iron, which improves the efficiency of iron bath type smelting reduction furnaces. Operational productivity will be greatly improved.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of an iron bath type smelting reduction furnace for implementing the present invention, and FIG. 2 is a diagram showing a conventional method of supplying powdered raw material to molten iron. FIG. 3 is a diagram showing another example of the present invention. Patent applicant Nippon Steel Corporation

Claims (1)

[Claims] In an iron bath type melting reduction furnace, iron oxide and carbonaceous material are added to a molten material consisting of molten iron and molten slag in a reaction vessel in which oxygen can be blown top-blown, and the iron oxide is reduced to molten iron by top-blowing acid. When blowing lumber or iron oxide powder into molten iron, one or more charcoal powders or iron oxide powders are blown into the molten iron bath using a carrier gas in a direction 15° to 60° away from the direction toward the center of the molten iron bath. A method for supplying powdered raw material to an iron bath type smelting reduction furnace, characterized by blowing from a blowing nozzle to make the molten iron bath swirl and flow.