JPS63179013A - Smelt-reduction method for top and bottom blow refining furnace - Google Patents

Abstract

PURPOSE:To make smelt-reduction of ore with high productivity by charging coke and various oxide metal ores onto the molten slag in a top and bottom blown refining furnace, ejecting an oxygen-contg. gas from bottom blowing nozzles in the form of bubbles and ejecting oxygen from plural top blowing lances in the positions deviated therefrom. CONSTITUTION:Solid carbonaceous fuel such as coke is charged to the surface of the molten slag 7 in the top and bottom blown refining furnace 2 provided with the plural oxygen top blowing lances 4a, 4b and bottom blowing nozzles 3a, 3b and the gaseous oxygen is blown from the lances 4a, 4b to burn the coke. The oxygen-contg. gas such as air is ejected from the nozzles 3a, 3b existing in the positions deviated from right under the lances 4a, 4b to stir and heat up molten iron 5 and the molten slag 7. The metal oxide-contg. raw materials such as Fe ore, Mn ore and Cr ore charged into the furnace are simultaneously melted and the Fe2O3, MnO2, Cr2O3, etc., in the ores are reduced to Fe, Mn and Cr which are then added to and incorporated into the molten iron 5. The alloy pig subjected to the component adjustment is thus smelted with high productivity.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention uses a top-bottom blowing type smelting furnace whose contents can be discharged by tilting, and melts the molten material (for example, hot metal and molten slag) in the furnace. Inject carbonaceous solid fuel (e.g. coke) into
The carbonaceous solid fuel is combusted by blowing oxidizing gas from the top blowing lance, and the combustion heat is used to convert the solid raw material (containing the oxide of the metal to be refined) into the furnace.
The present invention relates to an improvement in a smelting reduction method for melting iron ore, manganese ore, chromium ore, etc.) and promoting the reduction reaction of the oxide of the metal to be refined.

[Background of the invention and prior art]

A solid oxide raw material containing the target metal for refining and a carbonaceous solid fuel are introduced from the top of the furnace into the molten slag above the molten metal in a tiltable top-bottom blowing refining furnace (converter type reactor),
The carbonaceous solid fuel is combusted by blowing oxidizing gas from the top blowing lance, and the oxide raw material is dissolved and reduced by the combustion heat. The smelting reduction method using a top-bottom blowing smelting furnace is considered important as a method for smelting iron ore, manganese ore, chromium ore, etc. without relying on electricity.

What is the productivity of the smelting reduction method in this top-bottom blowing smelting furnace?

Dissolution rate of solid oxide raw material containing metal for refining purpose (hereinafter sometimes abbreviated as solid oxide raw material) and solid slag-forming material added as necessary.

It is determined by the reduction rate of the target metal oxide in the oxide. For this, +11. To efficiently burn the carbonaceous solid fuel input into the furnace, +21° to efficiently use this combustion heat for heating and melting the solid oxide raw material, (3+, reduction of the target metal oxide It is important to actively supply unreduced oxide to the so-called reaction site where the reaction proceeds.

Conventionally, in order to efficiently burn the carbonaceous solid fuel described in (1) above, it has been proposed to provide a large number of gas jet ports at the tip of the top blowing lance. In other words, a jet of oxidizing gas is sprayed onto the molten slag from a large number of gas outlets in a jet pattern that spreads outward.

This attempts to form a flash point over a relatively wide area.

Furthermore, since the purpose of (2) and (3) is to stir the contents, the most common method for carrying out this stirring is gas stirring from a bottom-blowing nozzle. Furthermore, a method has also been proposed in which a side blow nozzle is provided on the side wall of the reactor to assist in gas agitation.

JP-A-59-153819 discloses that the gas is not stirred from the bottom blowing nozzle or the side blowing nozzle, but the oxidizing gas is sprayed from the top blowing lance at the periphery of the bath surface, and this top blowing lance is placed in the furnace. Either the upper blowing lance is tilted and fixed in the tangential direction to the periphery of the bath surface, and the oxidizing gas is sprayed onto the carbonaceous solid fuel on the bath surface while swirling.

Alternatively, a method of swirling carbonaceous solid fuel with an oxidizing gas is disclosed. This method is said to avoid the phenomenon of carbonaceous solid fuel blowing up. It is also assumed that this method can achieve the objectives of tl+, +21, and (3) to some extent.

[Problem that the invention seeks to solve]

It must be said that the productivity of the smelting reduction method using a top-bottom blowing refining furnace is still very low compared to the normal converter steel manufacturing method.Because of this low productivity, the cost of refractories becomes enormous. Semi-submerged electric arc furnace method and giant AR which consume large amount of electricity
It may be less economical than the blast furnace method, which requires k*.

It must be said that this is true even if the above-mentioned known improvement method is adopted.

For example, in the method of increasing the number of jets at the tip of the top blowing lance and blowing the oxidizing gas in a widening direction, the diameter of each gas jet becomes small, which causes a significant pressure loss, so the spread of the gas jet is There are inherent limits, and it is difficult to expect productivity to far exceed the current level.

In addition, in the method of stirring gas from a bottom-blowing nozzle or a side-blowing nozzle, Ar, Nz+
When LPG+CO□ or the like is used, there is a problem of cooling, in which the temperature of the molten slag bath for carrying out the reduction reaction gradually decreases as the amount of blown gas increases. To avoid this cooling, when mixing oxidizing gases or simultaneously blowing oxidizing gases through a double pipe nozzle,
The problem of erosion of the blowing nozzle may arise, or the problem of blow-through may arise due to an increase in the amount of blown gas, and as a result, there is a limit to the ability to strengthen the stirring force by increasing the amount of blown gas.

The present invention is intended to solve these problems, and aims to provide a method for carrying out melting reduction with good productivity in a top-bottom blowing refining furnace.

[Means to solve problems]

The gist of the present invention, which aims to achieve the above object, is to charge carbonaceous solid fuel to the hot water surface containing melt in a top-bottom blowing type refining furnace whose contents can be discharged by tilting, and to Carbonaceous solid fuel is combusted by blowing oxidizing gas from a blow lance.

In the smelting reduction method, in which the combustion heat is used to melt a solid raw material containing an oxide of a metal to be refined, which is introduced into the furnace, and to proceed with a reduction reaction of the metal oxide to be refined, a plurality of top blowing lances are used. Oxidizing gas is sprayed vertically from each to the contents (molten slag surface on molten metal) to form multiple flash points, and the position of each flash point is deviated from the vertical position of the bottom blowing nozzle. It is characterized by being placed in a position. That is, the present invention is to form a plurality of stationary flash points on the bath surface of molten slag from a plurality of vertical top-blowing lances while performing gas agitation from a bottom-blowing nozzle.

By deviating the position of each fire point from the position of the bottom blowing nozzle, the combustion efficiency is improved while effectively stirring and flowing the molten slag layer.

Figures 1 and 2 show an example of a tiltable top-bottom blowing refining furnace to which the method of the present invention is applied. 3 is provided, and a plurality of lances 4a, 4b are inserted from the upper opening l. Hot metal 5 is charged into the refining vessel 2, and coke as a carbonaceous solid fuel and chromium ore as a raw material for solid oxide are introduced through the opening 1 at the top of the furnace, and slag making material is introduced as appropriate to melt and reduce the chromium ore. The method of the present invention will be specifically explained below, taking as an example a case where the method is implemented.

Hot metal 5 is charged into the container 2 while supplying an oxygen-containing gas such as air from the bottom blowing nozzle 3.

Coke and slag-making material are introduced from the upper opening 1, and oxidizing gas such as oxygen gas is blown onto the molten slag from the top blowing lances 4a + 4b to burn the coke on the bath surface. let When the hot metal temperature has risen sufficiently, open the
Start adding chrome ore.

When this chromium ore is added batchwise or continuously, coke is also added batchwise or continuously to replenish the carbon source necessary for temperature raising and reduction. During the treatment, the supply of gas from the bottom blowing nozzle 3 and the supply of oxidizing gas from each top blowing lance 4a, 4b are continued.
Each of the top blowing lances 4a, 4b is vertically fixed and blows oxidizing gas vertically onto the bath surface to form a plurality of stationary flash points 6a, 6b. At that time, each top blow lance 4
The positions of a and 4b are offset from the positions of the bottom blowing nozzles 3a and 3b, as seen in FIG. 2 showing the planar arrangement. In the illustrated example, two bottom blowing nozzles 3
a.

3b is provided at a certain distance from the reactor core on a straight line passing through the reactor core, and a top blowing lance is provided at a certain distance from the reactor core on a straight line orthogonal to the straight line where the bottom blowing nozzles 3a and 3b are present. An example is shown in which the positions of 4a and 4b are determined. More specifically, the bottom blowing nozzle and the top blowing lance are arranged in such a relationship that they are alternately located within an annular ring having a radius of .

A plurality of such fixed hot points 6a, 6b are formed, and these fixed hot points 6a, 6b are a plurality of fixed hot points each maintaining a high temperature by bottom-blowing gas from offset positions. The coke and chromium ore in the slag layer 7 are continuously supplied to 6a and 6b, and the dissolution and reduction reaction of the chromium ore proceed effectively. this is.

It is thought that the reduction reaction proceeds on or near the surface of high-temperature coke.2 According to the method of the present invention, a plurality of reaction sites are formed on or near the surface of high-temperature coke, and each reaction site has unreduced This is thought to be due to the continuous supply of chromium ore. In particular, when the target metal oxide is smelted and reduced as in the method of the present invention, an extremely large amount of slag layer 7 is constantly present during the process, unlike the normal converter steel manufacturing method. The thermal conductivity of such a slag layer 7 is significantly lower than that of hot metal, and therefore it is difficult to raise the temperature of the entire layer in a short time. When a plurality of points 6a and 6b are formed and unreduced substances are continuously supplied to each high-temperature fixed boiling point 6a and 6b by stirring with bottom-blown gas, the dissolution and reduction of the target metal oxide are It is thought that this will be actively promoted in some areas.

Further, by forming a plurality of stationary flash points as in the method of the present invention, the total area of the inner surface of the recessed portion of the molten slag bath increases. Therefore, even if the same amount of oxidizing gas as +i lance is distributed and supplied from multiple lances as in the present invention (even if the amount of gas supplied is the same as that of a single lance), in the case of a single lance, It is thought that the uniform mixing time is shortened in comparison. For these reasons, according to the method of the present invention, the workability of melting reduction treatment in a top-bottom blowing refining furnace is significantly improved. In addition, in the method of the present invention, metal does not adhere to each lance, and the life of the lance is not shortened.

EXAMPLES The effects of the present invention will be specifically illustrated by examples below.

Embodiment As shown in FIGS. 1 and 2, a 30-ton refining vessel 2 has two bottom blowing nozzles 3a and 3b at the bottom of the furnace.
20ONm' from each bottom blowing nozzle 3a, 3b.
C: 3.4%, Si: 0.3% + M while blowing 30% oxygen and 70% nitrogen gas at a flow rate of /hr nozzle.
n: 0.4%, P: 0.020%, S: o
, o2i%, Cr: 10.5% temperature is 141
First, 21.6 tons of chromium-containing hot metal at 0°C was charged.
2.0 tons of coke with the chemical composition values shown in Table 1 and
A total of 2.5 tons of quicklime and silica stone having the chemical composition values shown in the table are distributed so that the basicity of the molten slag produced is 1.0, and a total of 2.5 tons is charged into the container from the opening L at the top of the furnace. ~2 As shown in Figure 2, each bottom blowing nozzle 3a, 3b consists of two top blowing lances 4a fixed vertically at eccentric positions.
Oxygen gas was blown onto the bath surface from each of 4b with a lance of 255 ON+i'/hr, and the temperature of the chromium-containing hot metal was raised to 1600°C to form slag.

After that, semi-reduced chromium ore pellets with chemical composition values shown in Table 1) (Cr content reduction rate = 47%, Fe content reduction rate 28%)
4%), the basicity of coke and molten slag is always 0.
MgO+A in the range of 90-1.05 and in the slag
l, 0. While the temperature is low, the hot metal temperature is constantly maintained in the range of 1580 to 1640 °C while adding slag material so that the temperature is maintained in the range of 40 to 42%. The total 21.0 ton pellets were divided into 1/15 portions and charging was continued intermittently by withholding charging until the temperature was reached. It took 101 minutes from the start of charging the semi-reduced chromium ore pellets to the end of charging the entire amount. After all charging is completed, each top blow lance 4a +
After blowing for 7 minutes with the oxygen content of 4 B reduced to 1/2, top blowing was stopped, the furnace was tilted to discharge the slag and hot metal, and c near, 0%, Si: 0.2%.

Mn: 0.5%, P: 0.027%, S
:o, o36%, Cr:24.9% chromium-containing hot metal 31
．． Obtained 1 ton.

Comparative Example The same refining vessel as in the previous example was used, but with a single top blowing lance located in the center of the vessel, and C:3.
5%, Si: 0.4%, Mn: 0.3%.

P: 0.024%, S: 0.020%, C
r: 10.7% chromium-containing hot metal 21 with a temperature of 1420°C
．． 2) The same operation as in Example 1 was performed except that a tube was used. The amount of oxygen gas supplied from the top-blowing single lance is the total of the two lances in the above example. k (5100Nm3/hr).

In this example, a total of 5
1 (21,0)) It took 133 minutes to complete charging.

In addition, for 8 minutes after the completion of full charging, the amount of top-blown oxygen was increased to 172
The slag and hot metal were discharged in the same manner as in the previous example, and C: 6.8% + Si: 0.3% + Mn: O
-5%, P: 0.029%, S: o, o3
A chromium-containing hot metal of 31.5% and Cr: 24.5% was obtained.

As described above, the productivity of smelting reduction of chromium ore was improved by about 20% in the method of the present invention in the example, compared to the comparative example, even if the amount of gas in top and bottom blowing was the same. Recognize. In addition, the same top blowing lance 4 was used in the same operation as in the above embodiment.
The test was carried out 15 times using lances a and 4b, and then both lances were inspected for the presence or absence of adhered metal, but there was no adhered metal.

[Brief explanation of the drawing]

Figure 1 is a schematic sectional view showing an example of a top-bottom blowing refining furnace suitable for carrying out the method of the present invention, and Figure 2 shows the installation relationship between the bottom-blowing nozzle and top-blowing lance of the refining furnace shown in Figure 1. FIG. 2 is a schematic plan view for explanation. 1. Top opening, 2. Refining vessel, 3. Bottom blowing nozzle, 4. Top blowing lance, 5. Hot metal, 6. Fire point, 7. Molten slag layer.

Claims (1)

[Claims] Carbonaceous solid fuel is poured into the hot water surface containing melt in a top-bottom blowing type refining furnace whose contents can be discharged by tilting, and the carbonaceous solid fuel is blown by blowing oxidizing gas from a top-blowing lance. In the smelting reduction method, which uses the combustion heat to melt a solid raw material containing an oxide of a metal to be refined, which is put into a furnace, and to proceed with a reduction reaction of the metal oxide to be refined, a plurality of top-blowing lances are used. oxidizing gas is sprayed vertically onto the contents from each to form a plurality of flash points, and the position of each flash point is deviated from the position on the vertical line of the bottom blowing nozzle. Smelting reduction method in a top-bottom blowing refining furnace.