JP2959368B2 - Manufacturing method of Ni-Cr containing hot metal - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention uses a carbonaceous material as a fuel and a reducing agent, and melts and reduces Ni ore, Cr ore, semi-reduced chromium pellets, etc. together with hot metal in a converter type smelting furnace.
The present invention relates to a method for producing hot metal containing Ni and Cr.

[0002]

2. Description of the Related Art Conventionally, stainless steel is melted by scrap, alloyed iron such as FeCr or FeNi, or N 2 by an electrolytic method.
This has been done by re-melting raw materials such as i in an electric furnace or a converter. According to this method, Cr and Ni, which are the main components of stainless steel, are made of ferro-alloy reduced in advance in an electric furnace or the like and use expensive electric energy, so that they are not economical. From such a viewpoint, a method has been proposed in which Cr ore is used as a Cr source and melted and reduced in a converter or other melting furnaces as a more economical method for producing stainless steel.

On the other hand, a method of using inexpensive raw materials as a Ni source is to directly use molten FeNi in an electric furnace for the purpose of reducing FeNi melting cost [Iron and Steel, 69 (1983)
7, p. 59], a method of melting and reducing nickel matte in a converter (Japanese Patent Application Laid-Open No. 58-104153) or a method of preliminarily reducing a nickel oxide by mixing and molding a carbon material (Japanese Patent Application Laid-Open No. 60-36613). Gazette).

[0004] However, none of the conventional methods for producing a molten Ni-containing metal melt the Ni ore directly into a smelting furnace for smelting reduction. Since the Ni ore has a low Ni content of 2 to 3% by weight, about 70% of the Ni ore weight becomes slag, so that a large amount of slag is generated in the smelting reduction. Therefore, a large amount of slag is generated when trying to obtain a molten metal having a predetermined Ni concentration. For example, when 8% Ni-containing molten metal is obtained, 2-3 tons of slag are generated per ton of molten metal. Along with this, (1) Slopping (scattering of slag lump including metal particles from the furnace port) is generated by the reactant gas generated by the reducing agent or the oxygen and carbon material charged as a heat source during the smelting reduction process. It is difficult to perform regular operation, and there is a risk that the operation may become unstable. (2) Damage to equipment due to the above-mentioned slopping (3) Reduction of Ni yield due to the above-mentioned slopping is remarkable Become.

[0005] Because of these problems, in the above-mentioned conventional technique, Ni ore as a Ni source is not directly charged into a smelting furnace,
What used the thing which increased the ratio of the contained Ni component by performing some pre-processing is used. For the reasons described above,
Japanese Patent No. 221336 discloses a method for smelting and reducing Ni ore that can stably operate despite the generation of a large amount of slag, and can solve problems such as damage to equipment and equipment caused by slopping and a decrease in Ni yield. providing. In the smelting reduction method of Ni ore by the method, Ni ore is charged into a smelting furnace together with a carbon material and a slag-making agent, and oxygen is blown from a top-blown oxygen lance having nozzles for decarburization and secondary combustion, This is a method in which a stirring gas is blown from a bottom blowing tuyere provided at the furnace bottom of the smelting furnace to melt and reduce Ni ore.
The secondary combustion ratio (H ₂ O + CO ₂ ) / (H ₂ + H ₂ O + CO + CO ₂ ) in the smelting furnace is 0.3 or more.

According to this method, [C] in the molten metal is decarbonized as CO gas by oxygen for decarburization, and this CO gas is converted to CO ₂ gas by oxygen for secondary combustion.
The reaction heat of the decarburization and the secondary combustion is a main heat source of the smelting reduction, and the generated heat increases as the degree of oxidation of the exhaust gas from the smelting furnace represented by the above equation increases. Accordingly, it is possible to reduce the amount of carbon material to be supplied to the smelting furnace, and hence CO and CO ₂ gas, which are factors causing the occurrence of slopping, are reduced. Therefore, the frequency of occurrence of slopping is significantly reduced.

In Japanese Patent Application Laid-Open No. 2-274804,
After obtaining Ni-containing hot metal melted and reduced by the above-described method, the molten Ni-containing molten metal which has been dephosphorized and desulfurized by the process of discharging lime, fluorite, silica stone and carbonaceous material and desulfurizing the molten metal is obtained. After that, the Cr raw material is charged into the smelting furnace together with the carbon material and the slag-making agent into the smelting furnace, and the Cr ore is melted by acid supply from the top blowing oxygen lance and stirring by the stirring gas from the bottom blowing tuyere. A method for producing a Ni / Cr molten metal characterized by reduction is proposed.

[0008]

However, Japanese Patent Application Laid-Open Nos. 2-221336 and 2-2748 describe the above.
In the production of a molten Ni / Cr alloy in Japanese Patent Publication No. 04, there are the following problems. That is, as a furnace body refractory used in a smelting furnace generally used for smelting reduction, for example, magnesia bricks such as mag carbon and magcro brick can be considered, but since Ni smelting reduction is a long-term treatment, In high secondary combustion (high slag temperature), (1) elution of MgO into slag (2) elution (oxidation) due to reaction with FeO in slag (3) magcarbon (reduction) of MgO-C at high temperature Furnace body wear cannot be ignored due to reactions and the like. In addition, if bottom blowing is strengthened to increase thermal efficiency and countermeasures against slopping due to secondary combustion, spitting (dispersion of fine metal particles from the furnace opening) will increase, and as a result, the problem of metal loss will be ignored in actual production become unable.

The present invention has been made in view of the above circumstances, and overcomes the problem of furnace body brick wear, has no problem of spitting caused by bottom blown gas, and has a stable Ni ore without slopping. It is an object of the present invention to provide a method for producing a low-phosphorus / low-sulfur containing Ni / Cr hot metal that can perform a smelting reduction operation.

[0010]

Means for Solving the Problems The present inventors have conducted intensive studies on the direct smelting reduction of Ni ore, and have completed the present invention based on the knowledge described below regarding furnace body brick wear and operation stability. is there. That is, a first aspect of the present invention is to provide a converter type smelting furnace provided with a top blowing oxygen lance, a bottom blowing and / or a side blowing tuyere. (1) a. B. A step of injecting oxygen from a top-blown oxygen lance c. A step of blowing and stirring a stirring gas such as N ₂ or Ar, CO from a bottom-blowing and / or side-blowing tuyere. d. A smelting and reducing step of Ni comprising a step of obtaining molten Ni-containing hot metal by discharging the slag, and then (2) a dephosphorized / desulfurized hot metal by adding a solvent, an oxygen source, and / or a carbon material to the molten Ni-containing hot metal. Dephosphorization to get
Desulfurization step, then (3) a. Step of charging Cr ore, semi-reduced chromium pellets, etc. with medium solvent and carbon material to the dephosphorized / desulfurized hot metal b. Step of injecting oxygen from top-blown oxygen lance c. Bottom Step of blowing and / or stirring a stirring gas such as N ₂ or Ar, CO from a blowing and / or side blowing tuyere. D. Cr comprising a step of obtaining molten Ni-Cr hot metal by discharging slag
And the secondary combustion ratio (H ₂ O + CO ₂ ) / (H ₂ + H ₂ O + CO + CO ₂ ) represented by the following equation in the smelting reduction step of Ni: Characterized by maintaining Ni less than 0.3
This is a method for producing hot metal.

A second aspect of the present invention is the first aspect of the present invention.
In the Ni smelting reduction step, after the molten metal is discharged to a ladle to obtain molten iron containing Ni, then the molten iron containing Ni obtained in the ladle or is transferred to another smelting furnace, and the smelting furnace Performs the same dephosphorization and desulfurization step as in the first invention, then returns the dephosphorized and desulfurized hot metal to the smelting furnace in the smelting reduction step of Ni, and performs the same smelting reduction step of Cr as in the first invention to include Ni Ni-Cr containing iron, characterized in that it comprises a step of obtaining molten iron, and in the smelting reduction step of Ni, the secondary combustion ratio represented by the above formula is maintained at less than 0.3 as in the first invention. This is a method for producing hot metal. Further, a third aspect of the present invention is a method for producing hot metal containing Ni and Cr in the first or second aspect of the present invention, characterized by omitting a dephosphorization / desulfurization step.
Sixth, in the above-mentioned smelting reduction process of Ni, (1) adjusting the slag temperature to 1580 ° C. or less (2) T.C. Fe should be kept at 10% by weight or less. (3) The stirring gas flow rate from the bottom and / or side blowing tuyere should be 0.
This is a method for producing molten iron containing Ni / Cr, characterized in that the molten iron content is adjusted to 1 to 1.0 Nm ³ /min.ton.

[0012]

According to the present invention, as described above, in a converter type smelting furnace provided with a top blowing oxygen lance, a bottom blowing and / or a side blowing tuyere, first, hot metal is charged, and Ni ore and carbon material are added thereto. In charging and melting and reducing the smelting furnace, the secondary combustion ratio (H ₂ O + CO ₂ ) / (H ₂ + H ₂ O + CO + CO ₂ ) is maintained at less than 0.3, that is, the degree of oxidation of the exhaust gas is reduced. By lowering the temperature, the reaction heat is reduced and the smelting reduction is carried out, thereby achieving the object of the present invention of reducing the wear of the furnace structure of the smelting furnace. In the present invention, the reason why the secondary combustion ratio is limited to less than 0.3 is that when the secondary combustion ratio is set to 0.3 or more, as shown in FIG.
Even if the gO is controlled to be saturated, the slag temperature is 160
At 0 ° C. or higher, the wear of the furnace brick rapidly progresses.

In order to increase the secondary combustion ratio to 0.3 or more, it is necessary to use a lance having a complicated structure for a secondary combustion nozzle for increasing the degree of oxidation, and it is difficult to maintain the lance. In addition, there is a problem in operability such as difficulty in maintaining and controlling the high secondary combustion ratio at a constant level, and problems such as instability of the secondary combustion ratio during operation. However, when the secondary combustion ratio increases, the wear of the furnace body brick may be accelerated. From the above, the secondary combustion ratio was set to less than 0.3. Increasing the secondary combustion ratio increases the degree of oxidation, thereby increasing the calorific value and ensuring high productivity. At the same time, however, the heat transfer efficiency decreases, and the slag temperature increases. Therefore, in the present invention, the slag temperature in consideration of the heat transfer efficiency is set to 1580 ° C. or less.

On the other hand, when the secondary combustion ratio is lowered, the exhaust gas flow rate tends to increase, and the frequency of slopping tends to increase. However, as a result of intensive experiments, the present inventor has found that even when the secondary combustion ratio is low, the slopping occurs. I found a condition that can be suppressed. As shown in FIGS. 3 to 5 described later, the amount of the bottom blown gas is 0.1 Nm ³ /
If it is more than min.ton, T. Fe is 10% by weight
The following can be done, and the slopping can be suppressed. However, if the amount of bottom blown gas exceeds 1 Nm ³ /min.ton, FeO in the slag decreases, but spitting becomes severe and the yield deteriorates.
By setting it to 1.0 Nm ³ /min.ton, even without a secondary combustion ratio of less than 0.3, an operation without any slopping and spitting could be achieved. Furthermore, T. in slag Making the Fe concentration as low as 10% or less has an advantageous effect also on protection of the MgO-based furnace body.

[0015] Further, the obtained Ni-containing hot metal is drained, and then discharged into hot water remaining in the smelting furnace or discharged into a ladle, and then transferred to another smelting furnace, and then subjected to the smelting process. After adding a solvent medium, an oxygen source, and / or a carbon material to the smelting furnace water to obtain dephosphorized and desulfurized Ni-containing hot metal and sufficiently removing slag, Cr ore, semi-reduced chromium pellets, etc. The molten iron is charged together with a medium solvent and a carbon material, and melted and reduced in the same manner as in the above-described Ni smelting reduction step to obtain a hot Ni / Cr hot metal.
Also, once the hot water is poured into the ladle and dephosphorized in the ladle or another smelting furnace,
In the case of desulfurization, this dephosphorized and desulfurized hot metal is returned to the initial smelting furnace, and Cr ore, semi-reduced pellets, etc.
The Cr source is charged together with the carbonaceous material, and the Cr source is melt-reduced and reduced by stirring using acid gas from the top blowing oxygen lance and stirring gas from the bottom blowing and / or side blowing tuyeres. It becomes possible to produce Cr hot metal. Next, the present invention will be described by way of examples.

[0016]

【Example】

[Embodiment 1] FIG. 1 is an explanatory view of a converter type smelting furnace as an embodiment for carrying out the present invention. In FIG. 1, 10 is a converter type smelting furnace made of magnesia-based brick, 11 is a metal layer, 12 is a slag bath, 21 is an upper oxygen lance, 24
Is a bottom blowing tuyere, 25 is a hopper for charging the raw material Ni ore, carbonaceous material or slag material into a smelting furnace, 26 is a stirring gas, 27 is a slag thermometer, and 28 is a sample port for exhaust gas analysis. It is. The smelting furnace body 1 used in this embodiment
Zero capacity is 120 tons and acid supply is 35,000 Nm on average
³ / Hr.

Using such a smelting furnace body 10, various tests were conducted in batches for direct smelting reduction of Ni ore. First,
The operation procedure will be described. (1) Melt reduction step of Ni First, molten iron (Fe: 95% by weight)
0 ton, and then coke (FC: 8
(7% by weight), and oxygen is blown from the upper blowing oxygen lance 21 to raise the temperature of the molten metal to about 1500 ° C., and thereafter, charging of Ni ore is started. On the other hand, a stirring gas 26 such as N ₂ or Ar or CO is blown from the bottom blowing port 24 so as to prevent the bottom blowing port 24 from being blocked from the time when the hot metal is charged, and the blowing amount is increased as necessary. As a result, a smelting reduction reaction occurs, and as shown in FIG.
And the slag bath 12 is generated, and the slag is discharged about twice in the middle, and after 4 to 5 hours, the molten metal is discharged into a ladle to obtain hot metal containing Ni.

(2) Dephosphorization and Desulfurization Step As described above, after the smelting reduction of Ni ore is completed, a medium solvent such as lime and fluorite, a scale, and / or a carbon material are added to the molten iron containing Ni in the ladle. By charging and blowing oxygen from the top-blown oxygen lance 21, dephosphorization and desulfurization is performed outside the furnace, slag is sufficiently removed, and dephosphorized and desulfurized hot metal is obtained. After tapping the waste,
When performing dephosphorization / desulfurization, the above dephosphorization / desulfurization step is performed according to the above (1).
After the slag is discharged in the step, the smelting furnace is subjected to the remaining hot metal, or after discharging the slag, the hot metal is transferred to another smelting furnace, and the lime, fluorite, etc. The medium solvent, scale, and / or carbon material are charged, and dephosphorization and desulfurization is performed outside the furnace by blowing oxygen from an upper-blown oxygen lance to sufficiently remove slag to obtain dephosphorized and desulfurized hot metal. Is also good. (3) Cr smelting reduction step Next, the dephosphorized / desulfurized hot metal treated in this ladle or the dephosphorized / desulfurized hot metal in another smelting furnace is returned to the smelting furnace main body 10, and
Ore, semi-reduced chromium pellets and the like are charged together with a solvent and a carbon material, and are molten and reduced in the same manner as in the above (1) Ni smelting reduction step to obtain molten Ni-Cr hot metal. The dephosphorized and desulfurized hot metal may be successively melt-reduced in the smelting furnace body 10 in the same manner as in the process of smelting and reducing Ni to obtain molten Ni-Cr hot metal.

In order to determine the secondary combustion ratio (OD) in the smelting reduction process of Ni, the sample port 28 for exhaust gas analysis is used.
Exhaust gas is sampled, exhaust gas is analyzed, and H
₂ , H ₂ O, CO, and CO ₂ concentrations were determined and substituted into Find D. O. D = (H ₂ O + CO ₂ ) / (H ₂ + H ₂ O + CO +
CO ₂ ) This secondary combustion ratio can be adjusted by manipulating the height of the top blowing oxygen lance 21 and the amount of acid supply. For example, if the height of the upper oxygen lance 21 is increased, the CO ₂ concentration increases, and if the height of the lance is decreased, the CO ₂ concentration decreases and the secondary combustion ratio decreases. Similarly, the CO ₂ concentration goes up and down due to the increase and decrease in the amount of acid supply, so that the secondary combustion ratio goes up and down. Further, if the amount of the bottom-blown agitated gas is increased, the secondary combustion ratio is reduced, and if the amount of the bottom-blown agitated gas is reduced, the secondary combustion ratio is increased. Further, the slag temperature is adjusted by measuring the temperature by the slag temperature measuring element 27, and if the temperature is high, the ore and the slag-making agent are increased.

As described above, the secondary combustion ratio when the molten metal temperature was set to 1520 ° C. and the degree of wear of the MgO—C brick in the smelting furnace body 10 when the smelting reduction of Ni ore was performed were examined. In general, when the secondary combustion ratio is increased, the calorific value increases, and high productivity can be ensured, but at the same time, the slag temperature rises due to a decrease in the heat transfer efficiency. Therefore, the slag temperature was also investigated. FIG. 2 is a graph showing the relationship between the secondary combustion ratio, the slag temperature, and the wear index of the MgO-C brick when the temperature of the molten metal is set to 1520 ° C. during Ni smelting reduction. From FIG. 2, it can be seen that when the secondary combustion ratio is 0.3 or more, even if the MgO in the slag is controlled to be saturated, the slag temperature becomes 1600 ° C. or more, the furnace body wears rapidly, and the secondary combustion ratio increases. Is preferably less than 0.3. Slag temperature is 1580 ℃
The following shows that it is preferable to hold. High secondary combustion of 0.3 or more can be obtained by using an upper-blown oxygen lance of a complicated structure having a secondary combustion nozzle,
T. in the slag at this time Fe was 8% by weight or less in all cases.

On the other hand, when the secondary combustion ratio is lowered, the exhaust gas flow rate increases, and the frequency of slopping tends to increase.
In order to examine the effect of this point, the secondary combustion ratio is set to 0.1 to 0.
As T.3 in slag as A test was conducted to examine the relationship between Fe and the frequency of slopping. FIG.
5 is a graph showing the relationship between Fe (% by weight) and the frequency of slopping (%). As shown in FIG. It can be seen that the frequency of slopping is remarkably reduced by making Fe 10% by weight or less. Next, the effect of bottom-blown gas stirring to achieve this condition was investigated. Fig. 4 shows the amount of bottom blown gas and T.C. It is the graph which showed the relationship with Fe (weight%). As shown in FIG. 4, the amount of bottom blown gas is 0.1 Nm ³ /
T. in slag at min.ton It can be seen that Fe can be controlled to 10% by weight and the amount of bottom blown gas should be more than this. However, at 1 Nm ³ /min.ton or more, FeO in the slag decreases, but spitting becomes severe and the yield deteriorates. Further, the effect of the bottom blowing gas amount on spitting was examined from the results of FIG. FIG. 5 is a graph showing the relationship between the bottom blowing gas amount (Nm ³ /min.ton) and the spitting index. From the above, it can be understood that by setting the bottom blown gas amount to 0.1 to 1.0 Nm ³ /min.ton, even without a secondary combustion ratio of less than 0.3, it is possible to achieve an operation without slopping and no spitting at all. Was.

Example 2 Next, using the above-mentioned converter type smelting furnace, the batch was subjected to smelting reduction for 4 to 5 hours in the same operation procedure. As described above, the secondary combustion ratio at the time of the smelting reduction of Ni is set to a range of less than 0.3 because the furnace body wear becomes severe at a high secondary combustion ratio. On the other hand, if the secondary combustion ratio is less than 0.3, the occurrence of slopping becomes a problem as described above. Fe 5
% By weight or less.

In addition, furnace body wear during Ni smelting reduction can be reduced by controlling the actual slag temperature in addition to the factor of the secondary combustion ratio. Desirably, the temperature is set to 1550 ° C. The slag composition can be further reduced by controlling the slag composition. Fe 5% by weight or less,
The composition of MgO% in the slag is (saturation + 1%) or more. MgO% is added during operation with MgO-C brick debris etc. together with Ni ore and carbonaceous material, and MgO% becomes (saturated + 1%)
Always keep it below. T. in slag Fe5
% By weight or less was obtained with a bottom blown gas amount of 0.5 Nm ³ /min.ton, thereby reducing metal loss in long-term operation.

Under these conditions, the average ore of Ni ore having the following composition was 1200 kg / min, and the average coke was 650 kg / min.
smelting and reducing Ni ore at min.
The operation was repeated to obtain about 70 tons of molten iron containing Ni (9.7% Ni). The slag temperature could be maintained at 1550 ° C ± 20 ° C.

[0025]

[Table 1]

Further, lime (CaO: 2.9 ton) is added to the 70 ton Ni-containing hot metal obtained in the smelting furnace main body 10 by discharging the slag.
), Fluorite (CaF: 0.8 ton), silica stone (0.8 ton)
), A scale (1.0 ton), and coke (0.8 ton) were charged and dephosphorized and desulfurized by acid supply from the top blown oxygen lance 21 to be dephosphorized and desulfurized. Including N
i hot metal was obtained and slag was sufficiently removed. Thereby, N-containing
[P] in hot metal from 0.09% to 0.005%
[S] decreased from 0.15% to 0.01%. Then, the dephosphorized and desulfurized Ni-containing hot metal was mixed with C having the composition shown in Table 1.
r ore (500 kg / min) and coke (600 kg / min)
min) and charged together, and acid is fed from the top blowing oxygen lance 21 (amount:
25000Nm ³ / Hr), N ₂ gas from the bottom tuyere was blown and stirred at 2,500 Nm ³ / Hr from five tuyeres,
The r-source is melt-reduced and contains Ni and Cr as shown in Table 2 below.
About 95 tons of hot metal was obtained. The Ni concentration was finely adjusted by adding electrolytic Ni. At this time, the slag temperature was 1600 ± 20.
It was kept at ° C.

[0027]

[Table 2]

In the Ni smelting reduction operation of this embodiment,
In particular, no dust or fume was generated without slopping, and the measurement result of the rate of wear of the furnace body brick after 10 charge melting was 0.1 mm / hour, which was 1 to 2 m when the present invention was not carried out.
m / h, the wear rate was able to be suppressed significantly lower. Further, in the present embodiment, the dephosphorization and
Although the desulfurization step was performed, in the Ni reduction step, the same effects as in the present embodiment are obtained even if the dephosphorization and desulfurization steps are performed in the ladle or another smelting furnace after the waste is discharged to the ladle and discharged to the ladle. Things.

In the smelting furnace of this embodiment, the stirring gas was blown into the smelting furnace through the bottom tuyere to stir the smelting furnace. Stirring gas may be blown from both the tuyere and the bottom tuyere of the smelting furnace provided with both. If it is not necessary due to the concentrations of [S] and [P] in the hot metal, the desulfurization and dephosphorization steps are omitted, and the (1) smelting reduction step of Ni and (3) the smelting reduction step of Cr are performed. At N
The method for producing i.Cr hot metal is also included in the scope of the present invention. Further, the solvent, oxygen source, and carbon material charged in the desulfurization / dephosphorization step and the smelting reduction step of Cr in the present invention are not limited to those of the present embodiment, but may be any commonly used ones. It is.

[0030]

According to the present invention, acid is supplied from a top blowing lance to a converter type smelting furnace charged with raw materials such as hot metal, Ni ore, carbonaceous material, and slag-making material, and agitated gas is blown from the furnace bottom. By
The secondary combustion ratio was set to less than 0.3, and the T.C.
By controlling Fe, controlling the slag temperature, and optimizing the bottom blowing gas, the furnace body brick wear can be reduced, and the smelting and reduction of Ni ore with less slopping and spitting can be performed. By adding a medium solvent, an oxygen source, and / or a carbon material to the hot metal to obtain a dephosphorized and desulfurized Ni-containing molten metal, sufficiently removing slag, and then adding Cr ore, Charge half-reduced chromium pellets with a solvent and carbon
In the same manner as in the smelting reduction of
Cr hot metal is obtained, and it is possible to stably produce Ni-Cr hot metal having a low phosphorus and low sulfur concentration.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a converter type smelting furnace used in an embodiment of the present invention.

FIG. 2 is a graph showing a relationship between a secondary combustion ratio and a wear index of MgO—C brick in Examples.

FIG. 3 is a graph showing T.V. Fe (% by weight)
6 is a graph showing the relationship between the frequency and the dropping frequency (%).

FIG. 4 shows the amount of bottom blown gas (Nm ³ /min.to
n) and T. in slag. It is the graph which showed the relationship with Fe (weight%).

FIG. 5 shows the amount of bottom blown gas (Nm ³ /min.ton) in the embodiment.
7) is a graph showing the relationship between a spitting index and a spitting index.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Smelting furnace body 11 Metal layer 12 Slag bath 21 Top blowing lance 24 Bottom blowing tuyere 25 Raw material hopper 26 Stirred gas 27 Slag thermometer 28 Sample port for exhaust gas analysis

────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Tomohiko Uchino 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nippon Kokan Co., Ltd. (72) Inventor Hideo Nakamura 1-1-2, Marunouchi, Chiyoda-ku, Tokyo Nippon Kokan (56) References JP-A-2-221336 (JP, A) JP-A-2-285017 (JP, A) JP-A-2-274804 (JP, A) JP-A-58-104153 (JP, A A) (58) Field surveyed (Int. Cl. ⁶ , DB name) C21B 11/02 C21C 5/28 C22C 33/04

Claims (6)

(57) [Claims] In a converter type smelting furnace provided with a top blowing oxygen lance, a bottom blowing and / or a side blowing tuyere, (1) a. Hot metal is charged and Ni ore and carbon material are added to the hot metal. A step of charging oxygen into the smelting furnace b. A step of injecting oxygen from the top-blown oxygen lance c. N ₂ or Ar, C from the bottom-blow and / or side-blow tuyere
A step of blowing and stirring a stirring gas such as O. d. A smelting reduction step of Ni consisting of a step of obtaining molten iron containing iron by discharging, and (2) a medium solvent, an oxygen source, and / or Dephosphorization and de-sulfurization hot metal obtained by adding
Desulfurization step, and then (3) a. Step of charging Cr ore, semi-reduced chromium pellets, etc. with the medium solvent and carbon material to the dephosphorized / desulfurized hot metal b. Step of injecting oxygen from the top-blown oxygen lance c. N ₂ or Ar, C from the bottom and / or side blowing tuyere
Step of blowing and stirring a stirring gas such as O. d. Cr comprising a step of obtaining molten Ni-Cr hot metal by discharging slag.
(1) to (3) of the smelting reduction step of
The secondary combustion ratio (H ₂ O + CO ₂ ) / (H ₂ + H ₂ O + CO + CO ₂ ) represented by the following equation is maintained at less than 0.3 in the smelting reduction step i.
Hot metal manufacturing method. (1) In a converter type smelting furnace provided with a top blowing oxygen lance, a bottom blowing and / or a side blowing tuyere, a. Hot metal is charged, and Ni ore and carbon material are added to the hot metal. A step of charging oxygen into the smelting furnace b. A step of injecting oxygen from the top-blown oxygen lance c. N ₂ or Ar, C from the bottom-blow and / or side-blow tuyere
A step of blowing and stirring a stirring gas such as O. d. A smelting and reducing step of Ni which comprises a step of obtaining molten Ni-containing hot metal after draining and tapping into a ladle; Transferring to another smelting furnace, a dephosphorization / desulfurization step of obtaining a dephosphorized / desulfurized hot metal by adding a medium solvent, an oxygen source, and / or a carbon material to the smelting furnace,
Then, (3) a. A step of returning the dephosphorized and desulfurized hot metal to the smelting furnace of (1) and charging Cr ore, semi-reduced chromium pellets, etc. together with a solvent and a carbon material; b. C. N ₂ or Ar, C from the bottom and / or side blowing tuyere
Step of blowing and stirring a stirring gas such as O. d. Cr comprising a step of obtaining molten Ni-Cr hot metal by discharging slag.
And the secondary combustion ratio (H ₂ O + CO ₂ ) / (H ₂ + H ₂ O + CO + CO ₂ ) represented by the following equation in the smelting reduction step of Ni: Characterized by maintaining Ni less than 0.3
Hot metal manufacturing method. 3. The method for producing molten Ni-Cr hot metal according to claim 1, wherein the dephosphorization / desulfurization step is omitted. 4. The method for producing molten iron containing Ni and Cr according to claim 1, wherein the slag temperature is adjusted to 1580 ° C. or less in the smelting reduction step of Ni. 5. The method according to claim 1, wherein in the smelting reduction step of Ni, T.C. 5. The method for producing hot metal containing Ni and Cr according to claim 1, wherein Fe is kept at 10% by weight or less. 6. In the step of melting and reducing Ni, the flow rate of the stirring gas from the bottom-blowing and / or side-blowing tuyere is set to 0.1 to 1.
The method for producing Ni-Cr-containing hot metal according to claim 1, wherein the molten iron is adjusted to 0 Nm ³ /min.ton.