JP3119015B2 - Smelting reduction of Ni ore - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for smelting and reducing Ni ore using a carbonaceous material as a fuel and a reducing agent to melt and reduce Ni ore in a converter type smelting furnace.

[0002]

2. Description of the Related Art Conventionally, melting of stainless steel has been carried out by remelting raw materials such as scrap, alloy iron such as FeCr and FeNi, or Ni by an electrolytic method 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 this point of view, a more economical method for producing stainless steel is Cr.
A method has been proposed in which Cr ore is used as a source and is smelted and reduced in a converter or other melting furnace.

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). However, none of the above-mentioned known examples directly charge Ni ore into a melting furnace and perform smelting reduction. Ni
Since the ore has a low Ni content of 2 to 3% by weight, about 70% of the ore weight of the ore 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, to obtain an 8% Ni-containing molten metal, 2-3 tons per molten ton
Ton slag occurs. Along with this, slopping (scattering of slag lump containing metal particles from the furnace port) occurs due to the reactant gas generated by the reducing material or the oxygen and carbon material charged as a heat source in the smelting reduction process. Easy to do,
There is a possibility that the steady operation becomes difficult and the operation becomes unstable, and further (2) damage to the equipment due to the above-mentioned slopping, and (3) a decrease in the Ni yield due to the above-mentioned slopping becomes remarkable.

[0004] Because of these problems, in the above-mentioned known example, Ni ore as a Ni source was not directly charged into the smelting furnace, but was subjected to some kind of pretreatment to increase the proportion of the contained Ni component. Used. For the above reasons, Japanese Patent Laid-Open No. 2-2
Japanese Patent Application Laid-Open No. 21336 discloses a method for smelting and reducing Ni ore that can perform a stable operation despite the generation of a large amount of slag, and can solve problems such as damage to equipment and a decrease in Ni yield due to slopping. 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.
And it is characterized in that the secondary combustion ratio of the formulation smelting furnace _{[(H 2 O + CO 2} ) / (H 2 + H 2 O + CO + CO 2)] of 0.3 or more. According to this method, [C] in the molten metal is decarbonized as CO gas by decarburizing oxygen, and this CO gas is converted into CO ₂ gas by secondary combustion oxygen. This decarburization and 2
The reaction heat of the next combustion is the main heat source of the smelting reduction, and the generated heat increases as the degree of oxidation shown by the above equation of the exhaust gas from the smelting furnace 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.

[0005]

However, the smelting reduction method disclosed in JP-A-2-221336 in which the secondary combustion ratio is set to 0.3 or more has 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 bricks are considered, but since Ni smelting reduction is a long-term treatment, In high secondary combustion (high slag temperature), b) elution of MgO into slag b) (oxidation) elution due to reaction with FeO in slag c) furnace by high temperature magcarbon (reduction) reaction of MgO-C Body wear cannot be ignored. 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.

[0006] The present invention has been made in view of the above circumstances, and overcomes the problem of furnace body brick wear, does not have the 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 capable of performing a smelting reduction operation.

[0007]

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, the present invention relates to a converter type smelting furnace provided with a top blowing oxygen lance, a bottom blowing and / or a side blowing tuyere, and (1) directly into the smelting furnace together with the carbonaceous material without pre-reducing Ni ore. Step of charging (2) Step of injecting oxygen from the top-blown oxygen lance into the smelting furnace (3) Injecting a stirring gas such as N ₂ or CO into the smelting furnace from the bottom-blowing and / or side-blowing tuyere A slag temperature of 1580 ° C. or lower
Adjusted below, the secondary combustion ratio (H ₂ O + CO ₂ ) / (H ₂ + H ₂ O + CO + CO ₂ ) expressed by the following equation was maintained at less than 0.3 , and T.C. Fe 10 weight
% Or less, and the flow rate of the stirring gas from the bottom-blowing and / or side-blowing tuyere is adjusted to 0.1 to 1.0 Nm ³ /min.ton. Ma
Further, the present invention relates to a top blowing oxygen lance, a bottom blowing and / or a side blowing blade.
In a converter type smelting furnace provided with a port, (1) a step of charging Ni ore into the smelting furnace together with a carbon material; (2) a step of blowing oxygen from the top-blown oxygen lance into the smelting furnace (3) ) N ₂ or smelting furnace from the bottom blowing and / or Yokobuki tuyere
Molten reduction process in the process of injecting stirring gas such as CO.
Secondary combustion represented by the following equation in the process:
The ratio (H ₂ O + CO ₂ ) / (H ₂ + H ₂ O + CO + CO ₂ ) is kept at less than 0.3,
The stirring gas flow rate is 0.1 to 1.0 Nm ³ / min.
Adjust the amount of MgO in the lag to (saturation + 1%) or more
This is a smelting reduction method of Ni ore characterized by the following.

[0008]

As described above, the present invention relates to a converter type smelting furnace provided with a top-blowing oxygen lance, a bottom-blowing and / or a side-blowing tuyere.
When charging ore directly into the smelting furnace together with the carbonaceous material without pre-reduction and performing smelting reduction, the secondary combustion ratio (H ₂ O + CO ₂ ) / (H ₂ + H ₂ O + CO + CO ₂ ) is less than 0.3. In other words, the present invention achieves the object of the present invention to reduce the heat of reaction and reduce the smelting by reducing the degree of oxidation of the exhaust gas, thereby reducing the wear of the furnace body structure of the smelting furnace. In the present invention, the secondary combustion ratio is set to 0.1.
The reason for limiting to less than 3 is that when the secondary combustion ratio is 0.3 or more, as shown in FIG.
Slag temperature is 1600 ° C even when controlling to saturation
As described above, the wear of the furnace body brick progresses rapidly. In addition, in order to increase the secondary combustion ratio to 0.3 or more, it is necessary to use a lance of a complicated structure for the secondary combustion nozzle for increasing the degree of oxidation, which makes maintenance of the lance difficult. In addition, there are problems with operability such as difficulty in maintaining and controlling the high secondary combustion ratio at a constant level, and problems such as unstable secondary combustion ratio during operation. When the 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. The higher the secondary combustion ratio, the higher the degree of oxidation
Increases the amount of heat generated, ensuring high productivity, but at the same time
The slag temperature increases because the heat transfer efficiency decreases. Departure
In the light, the slag temperature is 1580 ° C or less in consideration of the heat transfer efficiency
And 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. However, as a result of the inventor's intensive experiment, the conditions under which the occurrence of slopping can be suppressed even at a low secondary combustion ratio are obtained. Was found.

As shown in FIGS. 2 to 4, which will be described later, if the amount of bottom blown gas is 0.1 Nm ^{3 /} min. Fe can be reduced to 10% by weight or less, and slopping can be suppressed. However, the bottom blowing gas amount is 1 Nm ³ / mi
Above n.ton, the amount of FeO in the slag decreases, but spitting becomes severe and the yield deteriorates. Therefore, the secondary combustion is performed by adjusting the bottom blowing gas amount to 0.1 to 1.0 Nm ³ /min.ton. Even with a ratio 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. Next, the effects of the present invention will be described with reference to examples.

[0010]

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 blowing lance, 24 is a bottom blowing tuyere, and 25 is Ni ore as a raw material. A hopper for charging a carbon material or a slag-making material into a smelting furnace; 26, a stirring gas; 27, a slag temperature detector; and 28, a sample port for exhaust gas analysis. 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 the smelting furnace body 10 as described above, various tests were conducted in batches on the direct smelting reduction of Ni ore. First,
First, about 50 tons of hot metal (Fe: 95% by weight) was charged into the smelting furnace body 10, and then coke (FC: 87% by weight) was charged as a carbon material. After blowing the oxygen from the blowing oxygen lance 21 to raise the temperature of the molten metal to about 1500 ° C., the supply of Ni ore having the following composition is started.

[0012]

[Table 1]

On the other hand, from the time when the hot metal is charged,
4 so as not be closed, the bottom吹羽port 24 N ₂ or A
A stirring gas 26 such as r, CO or the like is blown, and the blowing amount is increased as necessary to cause a smelting reduction reaction.
The metal layer 11 and the slag bath 12 are generated in the furnace body as shown in Fig. 7, and the waste is discharged about twice on the way, and the metal is discharged after 4 to 5 hours.

In order to determine the secondary combustion ratio (OD), the exhaust gas is sampled from the exhaust gas analysis sample port 28, the exhaust gas is analyzed, and the H ₂ O and CO ₂ concentrations are determined.
The secondary combustion ratio (OD) is obtained by substituting into the following equation. 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 lance height and the amount of acid supply of the top-blown oxygen lance 21. further,
The slag temperature is adjusted by measuring the temperature with a slag temperature measuring element 27. 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 and the wear index of the MgO-C brick, and also shows the slag temperature. From FIG. 2, it is found that when the secondary combustion ratio is 0.3 or more, the slag temperature becomes 16 even if the MgO in the slag is controlled to be saturated.
It can be seen that the temperature of the furnace reached 00 ° C. or higher, and the wear of the furnace body rapidly progressed, and the secondary combustion ratio was preferably less than 0.3. Further, it is indicated that the slag temperature is preferably maintained at 1580 ° C. or lower. High secondary combustion of 0.3 or more can be obtained by using an upper-blown oxygen lance having a secondary combustion nozzle. 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. As shown in FIG. 5, the operation without slopping and spitting can be achieved even when the secondary combustion ratio is less than 0.3 by setting the bottom blown gas amount to 0.1 to 1.0 Nm ³ /min.ton. I understood.

Next, the effects obtained by using the method of the present invention will be described. Using the converter type smelting furnace described above, smelting reduction of the batch was performed for 4 to 5 hours in the same operation procedure. As described above, the secondary combustion ratio at the time of smelting reduction 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 was set to 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, and is desirably set to 1550 ° C. as such. Furthermore, the slag composition can be reduced by controlling the slag composition. The composition is such that Fe is 5% by weight or less and MgO% in the slag is (saturation + 1%) or more. MgO% is added during operation by adding MgO-C brick debris and the like together with Ni ore and carbonaceous material.
%) Always keep below. T. in slag F
e5% 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 Ni ore is 1200
kg / min, coke average 650 kg / min
The ore was melt-reduced, and the waste was carried out twice to obtain about 70 tons of molten Ni (Ni: 9.7% by weight). The slag temperature could be maintained at 1550 ° C ± 20 ° C. In this operation, no dust and fume were generated without slopping, and the measurement result of the furnace brick wear rate after 10 charge melting was 0.1 mm / Hr.
The wear rate was significantly reduced as compared with 低 く 2 mm / Hr. The smelting furnace in this embodiment was stirred by blowing the stirring gas through the bottom tuyere, but was provided with the horizontal tuyere or both the bottom tuyere and the horizontal tuyere of the smelting furnace provided with the horizontal tuyere. The stirring gas may be blown from both the tuyere and the bottom tuyere of the smelting furnace.

[0020]

According to the present invention, acid supply from a top blowing lance to a converter type smelting furnace into which raw materials such as hot metal, Ni ore, carbonaceous materials, and slag-making materials are directly charged without preliminary reduction. By injecting stirring gas from the bottom, the secondary combustion ratio was set to less than 0.3. By controlling the Fe, controlling the slag temperature, and optimizing the bottom blowing gas , it is possible to reduce the wear of the furnace body brick, and it is possible to directly melt and reduce Ni ore with little slopping and spitting. Ma
If the secondary combustion ratio is less than 0.3, Mg in the slag
By adjusting the amount of O to (saturation + 1%) or more, the furnace body
Gas wear can be extremely effectively suppressed.

[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 Stirring gas 27 Slag temperature detector 28 Sample port for exhaust gas analysis

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hideaki Mizukami 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nippon Kokan Co., Ltd. (72) Inventor Hideo Nakamura 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nippon Kokan (56) References JP-A-60-36613 (JP, A) JP-A-1-162712 (JP, A) JP-A-2-221336 (JP, A) JP-A-2-274824 (JP, A A) (58) Field surveyed (Int. Cl. ⁷ , DB name) C22B 23/02

Claims (2)

(57) [Claims] In a converter type smelting furnace equipped with a top blowing oxygen lance, a bottom blowing and / or a side blowing tuyere, (1) Ni ore is directly loaded into the smelting furnace together with carbonaceous material without pre-reduction. (2) Injecting oxygen from the top-blown oxygen lance into the smelting furnace (3) Injecting a stirring gas such as N ₂ or CO into the smelting furnace from the bottom-blowing and / or side-blowing tuyere A slag temperature of 1580 ° C. or lower in this step.
Adjusted below, the secondary combustion ratio (H ₂ O + CO ₂ ) / (H ₂ + H ₂ O + CO + CO ₂ ) expressed by the following equation was maintained at less than 0.3 , and T.C. Fe 10 weight
% Or less, and the flow rate of the stirring gas from the bottom-blowing and / or side-blowing tuyere is adjusted to 0.1 to 1.0 Nm ³ /min.ton. 2. A blown oxygen lance, a bottom blow and / or a side blow blade.
In a converter type smelting furnace provided with a port, (1) a step of charging Ni ore into the smelting furnace together with a carbon material; (2) a step of blowing oxygen from the top-blown oxygen lance into the smelting furnace (3) ) N ₂ or smelting furnace from the bottom blowing and / or Yokobuki tuyere
Molten reduction process in the process of injecting stirring gas such as CO.
Secondary combustion represented by the following equation in the process:
The ratio (H ₂ O + CO ₂ ) / (H ₂ + H ₂ O + CO + CO ₂ ) is kept at less than 0.3,
The stirring gas flow rate is 0.1 to 1.0 Nm ³ / min.
Adjust the amount of MgO in the lag to (saturation + 1%) or more
A smelting reduction method of Ni ore characterized by the following.