JPS61279609A - Apparatus for producing high-chromium alloy by melt reduction - Google Patents

Abstract

PURPOSE:To produce a high-chromium alloy at a high yield with high efficiency by providing a top blowing lance and bottom blowing tuyeres in a refractory vessel contg. a metallic bath and providing side blowing tuyeres for slag to the vessel. CONSTITUTION:The metallic bath 2 is contained in a furnace 1 body and the slag 3 is formed above the bath 2. The top blowing lance 4 for blowing oxygen is sagged atop the slag 3 from an aperture 5 of the furnace body 1. On the other hand, the bottom blowing tuyeres 9, 9' for blowing a gas for stirring the metallic bath 2 are provided to the bottom of the furnace body 1. The side blowing tuyeres 6, 6' for blowing oxygen or the gas enrichedwith oxygen and an inert gas such as N2 or CO2 to the inside of the slag 3 are provided to the wall part of the body 1. The chromium reduction in the slag 3 is efficiently executed if the chromium raw material, carboneous material and fluxing agent are fed out of the banker 8 and the high-chromium alloy steel is produced by the melt reduction.

Description

[Detailed description of the invention] 11yo pmangetsubu! The present invention relates to an apparatus for producing high chromium alloys by smelting reduction using a refining furnace such as an oxygen top-blown furnace.

More particularly, the present invention relates to a smelting furnace equipped with an oxygen top-blowing lance, which is suitable primarily for carrying out chromium reduction in slag, and for producing high chromium alloys, such as stainless steel, by smelting reduction.

BACKGROUND ART Conventionally, high chromium steel such as stainless steel has been produced by reducing chromium ore with coke in an electric furnace to produce high carbon ferrochrome, and using this as a raw material. In other words, in this method, high temperatures are required for the reduction of ores with high Cr% to proceed, so they are treated with an excessive amount of carbonaceous material (
This is a two-step method in which high chromium steel is produced by melting the obtained ferrochrome together with an iron source and decarburizing it again in an electric furnace in the presence of coke.

However, this method called “indirect manufacturing method” has
When viewed as a consistent flow from chrome ore to stainless steel, there are the following problems.

(1) Expensive electricity is used as the large amount of energy required to reduce chromium oxide.

(2) Since ferrochrome manufacturing plants and steelmaking plants are generally located far apart, high-carbon ferrochrome is produced as a molten product, but it is solidified once and then remelted during the steelmaking process, resulting in large energy losses.

(3) Since a large amount of slag is smelted in contact with FEM chrome with high (Cr%), the (Cr%) in the slag
It is difficult to lower the chromium loss, and the loss of chromium is large.

Therefore, in order to reduce the cost of melting high chromium steel, it is necessary to solve these problems, and the following measures have been considered. In other words, (1) use cheap primary energy instead of electricity as energy for reducing chromium ore, (2) minimize energy loss in the integrated process from chromium ore to stainless steel, (3) ) It is necessary to minimize the amount of slag and create a reaction or reaction environment with a high Cr recovery rate.

Based on this technical idea, for example, Japanese Patent Application Laid-Open No. 54-15
No. 8320 proposes a method for producing chromium steel from chromium ore using a bottom-blown converter.
1 However, if chromium ore is directly added to hot metal,
□If MgO is the main component of chromium ore,
It is not easy to reduce poorly soluble chromite such as CrzOa.In order to reduce it efficiently, it is necessary to add SiO, CaO, etc., and
Promotes dissolution of O・Cr2O* into slag
It is necessary to
1 (1984) S, 114).

In order to solve such problems, Japanese Patent Application Laid-Open No. 60-981
Publication No. 5 discloses a method of melting and reducing the molten metal by keeping the temperature of the molten metal at 1650° C. or lower, controlling the amount of gas blown in from the bottom of the furnace, and limiting the slag composition and the amount of free carbon materials. However, this method requires strong stirring of the slag in order to reduce chromium, but there is a major difficulty in refining operations in that this stirring force is transmitted to the slag through stirring of the metal. That is, since the amount of metal stirring gas is extremely large, non-0□ type gas tends to cause a drop in metal temperature. If 0□ is included in order to maintain the temperature, there is a dilemma of oxidation of chromium in the metal. Furthermore, when separating the slag and metal after the second stage, it is difficult to reduce the amount of blown gas, resulting in an increase in metal loss as suspended particulate iron in the slag.

Problems to be Solved by the Invention The purpose of the present invention is to solve the problems of the prior art described above, and more specifically, to reduce chromium in a high yield without causing excessive wear and tear on the refractories in the furnace. An object of the present invention is to provide an apparatus for producing high chromium alloys by smelting reduction that can be realized in 1.

Means for Solving the Problems The present inventors achieve the above-mentioned objects of the present invention.
As a result of various experiments and studies, we have obtained the following knowledge and completed the present invention.
□1゜■ JP-A-54-158320 and JP-A-60-9
The method disclosed in Publication No. 815 uses a top-bottom blowing converter.
1 chromium reduction is performed, but when oxygen is blown into the metal bath, which should originally be a reducing atmosphere, the reduced chromium is re-oxidized and the chromium reduction rate is slowed down. In addition, special blowing equipment is required to bottom blow pulverized coal into a metal bath, which increases running costs.

■ On the other hand, in smelting reduction, chromium is reduced in slag, and the metal bath is treated as a medium to recover the chromium that falls due to reduction. Separate management of the slag and metal bath improves reaction efficiency, heat management, and fire resistance in the furnace. It was found that this is extremely preferable from the point of view of improving the basic unit of production.

■ In other words, it is sufficient to optimally adjust the chemical composition, temperature, and reducing atmosphere of the slag in order to improve the efficiency of the chromium reduction reaction and the recovery rate, while stirring the metal bath to the extent that it maintains a uniform temperature is sufficient. be.

■ Based on this technical idea, during periods when a large amount of heat source is required, such as at the chromium ore inlet, oxygen is not top-blown, but oxygen or oxygen-enriched gas is also blown into the slag. Heating and slag stirring will be strengthened. On the other hand, stirring gas is blown from the bottom of the furnace to make the temperature of the metal bath uniform, and the metal bath is heated only by conduction heating through contact with the slag.

In addition, during periods when a heat source is not required, such as after the completion of charging chromium ore, the amount of top-blown oxygen is reduced to maintain a balance between calorific value and heat absorption, and to reduce the oxygen concentration of the gas blown into the slag.

If a sufficient heat balance is achieved, it is more desirable to use an inert gas such as N2, CO2, or CO in order to further strengthen the reducing atmosphere within the slag. At this time, of course, oxygen is not used for stirring inside the metal, and heating is carried out through conduction from the slag.

In order to realize such a ROM reduction method, a special device is required, and in particular, it is necessary to provide a means for efficiently heating only the slag.

The present invention has been completed based on the above knowledge, and according to the present invention, there is provided a fireproof container which houses a metal bath therein, and a fireproof container which is provided under the surface of the metal bath of the fireproof container and which is provided inside the metal bath. a tuyere for blowing stirring gas into the refractory container; a top-blowing lance for blowing oxygen from the upper opening of the refractory container; A smelting reduction characterized by comprising a tuyere provided on the wall of the refractory container located at the slag for blowing oxygen or oxygen-enriched gas and an inert gas such as N2, CO2, CO into the slag. A high chromium alloy manufacturing apparatus is provided.

According to a preferred embodiment of the present invention, the tuyeres (hereinafter referred to as "side-blown tuyeres") for blowing oxygen or oxygen-enriched gas and inert gases such as N2, CO2, CO, etc. into the slag are refractory. Oriented off the vertical axis of the container. Also, when equipped with multiple side-blown tuyeres,
Preferably, they are spaced approximately equally spaced around the refractory vessel and oriented at an angle offset from the vertical axis to provide rotational agitation of the slag.

Furthermore, according to a preferred embodiment of the invention, the side-blown tuyere is constructed from a double pipe, the inner pipe being connected to an oxygen source,
Meanwhile, the outer tube is connected to a cooling gas source.

The cooling gas may be an inert gas such as nitrogen or argon, as well as Co or CO2.

In the high chromium alloy manufacturing apparatus of the present invention, the slag is blown with oxygen by the top blowing lance and the side blowing lance, while only the stirring gas is blown into the metal bath from the bottom blowing tuyere. Therefore, the carbonaceous material in the slag is burned by oxygen, heating the slag and reducing the chromium raw material in the slag.
On the other hand, the metal bath is heated only by contact with the slag and is uniformly heated by stirring.

In this way, the slag temperature and reducing atmosphere can be adjusted separately from the metal bath so that the chromium reduction in the slag is optimized, while the chromium reduction in the metal bath is not blown into the metal bath. It is possible to prevent reoxidation, achieve high efficiency and high yield chromium reduction, and reduce the unit consumption of refractories.

EXAMPLES Hereinafter, the present invention will be explained by examples with reference to the accompanying drawings, but these examples are merely illustrative of the vehicles of the present invention, and do not limit the technical scope of the present invention. .

FIG. 1 is a schematic cross-sectional view of one embodiment of the high chromium alloy manufacturing apparatus according to the present invention, and FIG. 2 is a schematic diagram showing the area where slag and blown oxygen come into contact in the apparatus shown in FIG. It is.

The equipment shown in Figure 1 is a smelter that is a modified upper-bottom blowing converter.
Although it is a furnace, the apparatus of the present invention does not have to be a converter type, and may be a modified electric furnace, for example.
1.! - In FIG. 1, a furnace body 1 is lined with, for example, magnesia-chromate bricks, and a metal bath 2, for example hot metal or molten steel, is accommodated inside the furnace body 1. A slag 3 is formed above the metal bath 2 , and a top blowing lance 4 for blowing oxygen into the top surface of the slag 3 is provided hanging down from above the opening 5 of the furnace body 1 . Oxygen or oxygen-enriched gas and N2, CO□,
c.

A horizontal blowing tuyere of 6.6° for blowing inert gas such as the like is provided on the furnace wall of the furnace body 1. Further, an exhaust gas recovery hood 7 is removably attached to the opening 5 of the furnace body 1, and a bunker 8 is provided for adding chromium raw materials such as chromium ore and reduced pellets, carbon materials such as coke, and solvents into the furnace. It is provided.

On the other hand, a tuyere 9.9° is provided at the bottom of the furnace body 1 to blow gas into the metal bath 2 in order to stir it.

To produce high chromium alloy steel by smelting reduction using the apparatus of the present invention, chromium raw materials, carbonaceous materials, and solvent materials are cut out from the bunker 8 and placed onto the metal bath 2 made of molten steel.
The slag 3 is formed by blowing oxygen through the top blowing lance 4 and blowing oxygen or oxygen-enriched gas through the side blowing tuyere 6.6''.

Figure 2 shows the portion of the slag that comes into contact with oxygen blown from the top blow lance 4 and the side blow tuyere 6.6''. The portion a and the contact portion a2 between the slag and the oxygen blown from the side blowing tuyere 6.6'' occupy a considerable portion of the horizontal cross section of the slag 3. In addition, the blowing direction of the horizontal blowing tuyere 6.6° is set to be offset from the radial direction of the horizontal cross section of the furnace body 1, so that the slag is effectively stirred, while the top blowing lance 4 is placed at a height position. It is preferable to adjust the area of the contact portion al of oxygen with the slag to be large by changing the horizontal position.

As described above, only the carbonaceous material is introduced from the bunker 8 and oxygen is blown into the slag 3 to oxidize the carbonaceous material and heat the slag, and at the same time, chromium reduction in the slag is carried out. On the other hand, stirring gas is blown into the furnace bottom tuyere 9.9°, and the metal bath 2 is stirred at the same time.
Contact with the lug 3 causes conductive heating. -Therefore,
) The metal bath 2 is held in a reducing cloud without contacting oxygen, receives chromium reduced in the slag, and is heated by the slag as described above, so that fluidity can be maintained.

When this slag formation is completed, the injection of the chromium raw material and solvent from the bunker 8 is stopped, and only the carbonaceous agent is introduced.
Inert gas such as N2, CO2, CO, etc. is blown from the side blowing tuyere at 6.6°, and stirring gas such as nitrogen is blown from the bottom blowing tuyere at 9.9°.

FIG. 3 is a schematic cross-sectional view of a horizontal blowing tuyere made of double pipes. This side-blown tuyere consists of an inner pipe 11 and an outer pipe 12,
Inner tube 11 is connected to an oxygen source (not shown) to supply slug 3
The outer tube 12 is connected to a cooling gas source (not shown) to cool the inner tube 11 while cooling the inner tube 11.
Inject gas into the slag.

After cooling the inner tube 11, this cooling gas is blown into the slag to agitate the slag.

As described in detail above, the apparatus for producing high chromium alloy by smelting reduction according to the present invention differs from conventional apparatus in that the slag contains oxygen or oxygen-enriched gas and N2, CO□, GO, etc. Equipped with a dedicated blade for blowing inert gas, it efficiently reduces chromium in the slag.
[<Extremely suitable for implementation.]
Furthermore, since the metal bath is simply stirred and no oxygen is blown into it, re-oxidation of chromium does not occur within the metal bath, and the stirred metal bath is kept at a uniform temperature. Maintains the molten state of perilla.
[Therefore, when manufacturing high chromium alloys by smelting reduction, the temperature and reducing atmosphere of the slag must be adjusted separately from the metal bath so that the rim reduction takes place within the slag [1. can be carried out with high efficiency and high yield.
[Ideal for manufacturing aluminum alloys.]
l・11'

[Brief explanation of drawings]

Figure 1 1 This invention 1. High, follow. 4 alloy manufacturing equipment.
111 is a schematic cross-sectional view of Example 111,
Blind. lI' Figure 2 shows the slag and blowing in the equipment shown in Figure 1.
It is a schematic diagram showing a region in contact with oxygen.
, ), , Figure 3 is a schematic cross-sectional view of a horizontal blowing tuyere consisting of double pipes [:9i':' Figure 1A6.
Ill b: (Main reference numbers) 1...furnace body, 2...metal bath, 3...slag, 4...top blowing lance, 6.6°
...Side blowing tuyere, 7...Exhaust gas recovery hood, 8...Bunker, 9.9°...Bottom blowing tuyere,

Claims (3)

[Claims] (1) A fireproof container that houses a metal bath inside, a tuyere that is provided below the metal bath surface of the fireproof container to blow stirring gas into the metal bath, and an upper opening of the fireproof container. A top-blowing lance is provided on the wall of the refractory container located below the surface of the slag formed on the metal bath and above the metal bath surface, and is provided in the wall of the refractory container to blow oxygen into the slag. An apparatus for producing a high chromium alloy by smelting reduction, characterized by comprising a tuyere for blowing oxygen or oxygen-enriched gas and an inert gas such as N_2, CO_2, CO, etc. (2) The tuyere for blowing oxygen or oxygen-enriched gas and inert gas such as N_2, CO_2, CO into the slag is oriented offset from the vertical axis of the refractory container. An apparatus for producing a high chromium alloy by melt reduction according to claim 1. (3) The tuyeres for blowing oxygen or oxygen-enriched gas and inert gases such as N_2, CO_2, and CO into the slag described above are composed of double pipes, and oxygen or oxygen-enriched gas is injected from the inner pipe. 3. The apparatus for producing high chromium alloy by melt reduction according to claim 1 or 2, wherein cooling gas is blown into the outer tube.