KR101714920B1 - Method for manufacturing nickel containing steel and ferronickel cake for manufacturing nickel containing steel - Google Patents

Abstract

The present invention relates to a method of manufacturing nickel containing steel, and ferronickel cake to manufacture nickel containing steel. According to one aspect of the present invention, the method of manufacturing nickel containing steel comprises: a step of preparing the ferronickel cake containing oxidized ferronickel; a step of placing the ferronickel cake into an AOD refining furnace; and a step of enabling the ferronickel cake to be reduced to recover the nickel and steel to molten steel.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a method for producing a nickel-containing steel, and a ferronickel cake for producing a nickel-

The present invention relates to a method for producing nickel-containing steel and a ferronickel cake for manufacturing nickel-containing steel. More specifically, the present invention relates to a ferronickel cake for nickel- Containing steels and a ferronickel cake which can be suitably used therefor.

Process lines which have been operated so far for the production of nickel-containing steels are made by preparing molten steel in a converter or electric furnace (EAF), then controlling the composition and temperature in the secondary refining process.

As a raw material for adjusting the nickel component in the nickel-containing steel, ferronickel is exemplified. Such ferro-nickel (Fe-Ni) can be obtained from high-grade ores including nickel and iron.

Such ferronickel can be produced, for example, by forming a semi-finished product of nickel from an ore containing nickel and iron by wet smelting, then subjecting the semi-finished nickel product to a reduction and melting process in a dedicated electric furnace called SAF (Submerged Arc Furnace) Followed by an additional desulfurization process. The ferronickel obtained by this process contains, for example, about 18% by weight of Ni and 82% of Fe.

The ferronickel (Fe-Ni) of 18 wt% Ni and 82 wt% Fe is used as a raw material for steel making of nickel-containing steel, and for example, as a raw material for steel making of Fe-Cr- . ≪ / RTI >

However, since the conventional metal ferronickel (Fe-Ni) is manufactured through dissolution, desulfurization and reduction processes in a ferronickel production apparatus called SAF (Submerged Arc Furnace), the processing cost is increased and the process efficiency is decreased there is a problem.

Accordingly, one aspect of the present invention provides a method for producing a nickel-containing steel using an efficient ferronickel as a raw material and a ferronickel cake for manufacturing a nickel-containing steel, wherein the process is simple and the processing cost is reduced.

The object of the present invention is not limited to the above description. It will be apparent to those skilled in the art that the present invention may be practiced without departing from the spirit and scope of the invention.

According to an aspect of the present invention, there is provided a method of preparing a nickel-containing steel, comprising: preparing a ferronickel cake containing ferronickel in an oxide state; Introducing the ferronickel cake into an AOD refining furnace; And recovering nickel and iron into the molten steel by reducing the ferronickel cake.

A ferronickel cake for the production of nickel-containing steel according to still another aspect of the present invention comprises ferronickel in the form of an oxide comprising 9 to 12% by weight of nickel and 35 to 40% by weight of iron, ferronickel containing at least one of a binder and a reducing agent Wherein the binder is added in an amount of 6 to 12% by weight of the organic binder and 2 to 7% by weight of the inorganic binder in the total weight of ferro nickel, and the reducing agent is added to the equivalent amount of oxygen in the oxide type ferronickel Or more.

According to the present invention, the ferro-nickel oxide can be reduced at the time of steel refining by using the reducing function of the AOD refining furnace, and can be directly added to the molten steel, thereby reducing the burden imposed on the SAF (Submerged Arc Furnace) It is possible to obtain the effect of the reduction of the distribution cost due to the transportation.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, the embodiments of the present invention can be modified into various other forms, and the scope of the present invention is not limited to the following embodiments.

According to the present invention, ferronickel in the oxide state obtained by reduction, slurrying, leaching and substitution process from nickel ore is directly subjected to AOD (Argon Oxygen Decarburization) in a cake form (hereinafter simply referred to as a ferronickel cake) So as to produce nickel-containing steel efficiently. AOD refers to a refining apparatus that performs a reaction such as decarburization while blowing argon gas and oxygen gas into a ladle containing molten metal. In addition to the decarburization reaction, the AOD may be subjected to a reduction desulfurization reaction, a reduction reaction of elements such as chromium, and the like, and one or more of the above reactions may be performed in a time series or simultaneously, if necessary. The molten steel is taken into the AOD refining furnace when the ferronickel is charged.

That is, the AOD treats molten steel at a high temperature of, for example, 1,600 ° C. or more and 1,700 ° C. or more, for example, so that it is possible not only to smoothly supply the heat required for reduction of ferronickel but also to form a reducing atmosphere at the end of the operation, And the sulfur (S) component contained in the ferronickel can be desulfurized into slag in a reducing atmosphere. Therefore, it is possible to obtain a more advantageous effect than when the nickel-containing steel is added to another process at the time of steel making.

In the prior art, the ferronickel in the oxide state is transferred to the SAF (Submerged Arc Furnace) to perform reduction and melting. In the present invention, however, since the ferroalloy is directly injected into the AOD, So that the transfer route of the material can be simplified and the valuable metal such as nickel and iron can be economically recovered.

That is, one aspect of the present invention includes preparing a ferronickel cake containing ferronickel in the oxide state, and then introducing it into an AOD refining furnace. At this time, the ferronickel cake is preferably introduced before the reducing unit of the AOD refining furnace, and it is more preferable to introduce the ferronickel cake into the decarburizer. That is, when the ferronickel cake is fed during or after the reducing machine, it is difficult to expose the ferronickel cake to the reducing atmosphere for a sufficient time, and the recovered amount of the valuable metal may be insufficient. In addition, it is advantageous for the cake to be decomposed beforehand by the heat of the molten steel and the slag to be reduced to a sufficient surface area in advance, preferably before the reducing unit. In addition, when a ferronickel cake made of an oxide is fed into a decarburizer, it is advantageous to form an oxidizing atmosphere favorable to the decarburization reaction, so that the ferronickel cake is more advantageously introduced before or after the decarburizer, and in one embodiment It is advantageous to introduce it before decarburization.

In the present invention, the nickel-containing steel is preferably stainless steel, particularly preferably Fe-Cr-Ni-based stainless steel. Such Fe-Cr-Ni-based stainless steels are also known as 300 series stainless steels.

The ferronickel in the oxide state includes 8 to 12% by weight of nickel and 35 to 45% by weight of iron, and generally comprises about 9% by weight of nickel and about 45% by weight of iron. Other components of the ferronickel cake may include oxygen and a small amount of impurities. Particularly, the nickel content of the ferronickel in the oxide state should be not less than 8% by weight and can be effectively recovered into molten steel. If the nickel content is lower than that, nickel and molten steel may increase in amount of slag, It is not preferable. In particular, when a nickel ore or the like containing a small amount of nickel is directly introduced into the AOD refining furnace, not only the recovery rate of nickel is lowered but also various impurities contained in the ore may be mixed into the molten steel.

Exemplary components of the ferronickel in the oxide state that can be included in the ferronickel cake of the present invention are shown in Table 1.

Ni Fe Al Cr Cu Mg Mn Ca Co Si Zn O 8.95% 44.66% 2.61% 2.02% 0.01% 2.44% 0.63% 0.40% 0.25% 5.78% 0.02% 32.23%

Unit: wt%

According to one embodiment of the present invention, the ferronickel cake may be added to the AOD refining furnace in the form of a mixture of ferronickel oxide in the form of oxide and at least one of a binder and a reducing agent. However, the present invention is not necessarily limited to this, and according to further embodiments of the present invention, the ferronickel cake may be used in a form obtained by molding ferronickel in the form of oxide at high temperature as it is.

The binder is intended to prevent the pulverized ferrous nickel cake from being sucked and lost by the dust collector due to the weak bonding strength. When the binder contains the binder composition, the binder may contain the weight of the entire composition (that is, By weight based on the total weight of the composition. When the binder is contained in an amount of 11% by weight or more, the amount of the powder that is pulverized when injected into the AOD can be minimized, but when the binder is contained in an amount exceeding 15% by weight, the nickel concentration in the ferronickel cake There is a problem that the manufacturing cost of the final product increases with an increase in the binder content, thereby increasing the manufacturing cost.

Meanwhile, in one embodiment of the present invention, the binder usable as the binder may be a mixture of an organic binder and an inorganic binder. If only the organic binder is used, the age hardening does not occur, and there is a problem of strength reduction during long-term storage. In the case of using only the inorganic binder, the initial strength is weakened, and there is a risk of damage in processing such as transportation.

More preferably, the binder comprises from 6 to 12% by weight of an organic binder and from 2 to 7% by weight of an inorganic binder, and in this case, an addition composition with a more suitable strength for charging into the AOD refining furnace can be obtained. In one embodiment, the organic binder may be limited to 8 to 9 wt%, and the inorganic binder may be limited to 3 to 4 wt%.

The organic binder which can be used in the present invention is preferably at least one selected from the group consisting of carbon (C) based binders. For example, molasses and the like may be used, and the inorganic binder may be at least one selected from the group consisting of cement, Alumina, and calcium silicate, and most preferably, a mixture of cement and molasses is used. The kind of the cement is not particularly limited, but for example, Portland cement and the like can be used.

The reducing agent that can be used in the present invention is not particularly limited, but one or more of cokes, Fe-Si, and aluminum may be used in combination. Of these, the use of cokes is economically advantageous. More preferable. The amount of the reducing agent is preferably included in an amount proportional to the equivalent amount of oxygen contained in the ferronickel in the oxide state (for example, one time the amount of the minimum reducing agent required to stoichiometrically reduce oxygen contained in the ferronickel The upper limit does not need to be specified, but if it is too large, it is not economically advantageous, so it may be limited to 2 times or less, 1.5 times or less, or 1.3 times or less).

Considering the heat balance of the molten steel, it is preferable that the ferronickel cake be charged at a rate of 5% or less or 2% or less of the weight of the molten steel before charging. In order to achieve a substantial charging effect of ferronickel, Or more. When the amount of the ferronickel cake is too small, the effect of feeding the ferronickel is not sufficient. On the contrary, when the amount of the ferronickel cake is too large, the electric furnace tempering temperature becomes excessively high to compensate the excessive amount, Which is undesirable.

The temperature at which the ferronickel is introduced is not particularly limited, but it is preferable that the temperature of the molten steel during the operation after the charging of ferronickel is maintained at 1650 ° C or more is included so that the loaded ferronickel can be sufficiently melted . The upper limit of the molten steel temperature is not particularly limited, but it may be kept at 1750 占 폚 or less in consideration of problems such as burden of operation and refractory loss.

According to one embodiment of the present invention, the oxide-state ferronickel that can be applied to the present invention includes a slurrying step of slurried reduction light for leaching nickel ore reduced to hydrogen-containing gas, for example; A leaching step of adding hydrochloric acid or sulfuric acid to the slurry to dissolve nickel and iron from the leaching reduction light to produce an immersion liquid; And ferric oxide in an oxide state obtained by adding a reducing light for precipitation of nickel ore reduced with a hydrogen-containing gas to the above-mentioned leaching solution to replace the iron component in the nickel ore and the nickel ion in the leaching solution.

The process for obtaining ferronickel in a more detailed oxide state is as follows.

In one preferred embodiment of the invention, nickel reduction ore (also called reduced nickel iron containing material) is leached into the leach solution to extract nickel ions. At this time, the nickel reduced ore can be used by reducing nickel and iron containing raw materials.

The nickel and iron-containing raw materials that can be used in the present invention are not particularly limited, and nickel ores such as nickel ores such as limonite and saprophite are preferably used.

In recovering the nickel-reduced ore from the nickel-and-iron-containing raw material, a pretreatment step may be optionally performed so that the nickel-iron-containing raw material can be effectively reduced in the reduction process described below. Such pretreatment processes include drying, grinding and calcining steps.

The nickel iron containing feedstock, which is the raw material used for nickel recovery, is preferably an atomized powder for efficient reduction and subsequent smooth leaching processes. Thus, the nickel iron containing feedstock may have a pulverized form.

In this case, the nickel-iron-containing raw material, which is usually used as raw material, generally contains about 30 to 40% of the number of the attached water and about 10% of the crystalline water. In order to improve the pulverization efficiency, .

The drying of the nickel ore can be carried out under the condition that the water of adhesion in the nickel ore can evaporate, for example, by heating to a temperature in the range of 100 to 200 ° C. In order to improve the reduction and leaching efficiency, it is preferable to crush the particle size to 1 mm or less. On the other hand, the lower limit of the particle size is not particularly limited, but may be limited to 10 mu m or more for convenience of the pulverization process.

On the other hand, the crystal water contained in the nickel-iron-containing raw material that has not been removed in the drying process is released as water in the reduction process during the reduction reaction of the nickel-iron-containing raw material. , And a step of firing the nickel-iron-containing raw material to remove such crystal number can be further performed.

At this time, among the nickel-iron-containing raw materials, since the limonite ore has a characteristic of emitting crystal water at about 250-350 ° C and the saprophorite at 650-750 ° C, the firing process is performed at 250-850 ° C Lt; / RTI >

Subsequently, a step of reducing nickel and iron of the pretreated nickel-iron-containing raw material as described above is carried out. In one embodiment of the present invention, this reduction step can be carried out in the temperature range of 550-950 DEG C using a reducing gas comprising hydrogen as a reducing agent. When the reduction temperature is less than 550 ° C., the reduction does not occur sufficiently, so that the recovery rate upon leaching into the acid solution in the subsequent step is low, and the precipitation yield is also lowered. On the other hand, the higher the reducing temperature, the higher the leaching yield and the precipitation yield. However, in the case of reduction at a temperature exceeding 950 占 폚, there is no problem in reducing the nickel-iron-containing raw material, however, no further reduction in the reduction efficiency can be obtained and, rather, intergranular sintering may occur, The specific surface area is reduced to 1 m < 2 > / g or less, which may result in a decrease in precipitation yield.

As the reducing gas, a gas containing hydrogen may be used. When a hydrogen-containing gas is used as the reducing gas, a reduction process can be performed at a lower temperature than the carbon reduction, and a nickel metal having a specific surface area of 1-100 m 2 / g can be produced, It can be easily dissolved by the acid, so that the subsequent acid leaching process can be carried out at high speed.

As such a reducing gas, not only hydrogen can be used alone, but also inert gases such as helium, argon, carbon dioxide, and nitrogen can be used together. Further, another example that can be used as the hydrogen-containing reducing gas is a gas generated from a coke oven gas (COG) containing 50% or more of hydrogen generated in the iron ore smelting process or a methane hydrogen reforming reaction, And hydrogen-containing LNG reforming gas containing 65% or more of hydrogen.

The nickel and iron raw materials reduced by the reaction can be obtained. The reduced nickel iron-containing raw material is hereinafter referred to as a reducing raw material.

After the exhaust gas obtained in the reduction step is discharged and separated, the reducing raw material is slurried using water. It is preferable that the slurrying proceeds in an oxygen-free state in which the inflow of external air is blocked in order to prevent the reducing raw material from being reoxidized by oxygen.

And an acid leaching step of ionizing nickel and iron into ions by dissolving and dissolving nickel and iron contained in the reducing raw material in the slurry after adding the slurry to the reducing raw material. The acid leaching step may dissolve the reducing raw material by adding an acid to the slurried reducing raw material in an anaerobic reactor and agitating it. The acid used in the acid leaching step is not particularly limited, but hydrochloric acid or sulfuric acid may be used.

On the other hand, Al ₂ O ₃ , SiO ₂ , and Cr ₂ O ₃ contained in the nickel-iron-containing raw material hardly dissolve by the acid, and are obtained as solid phase residues. Therefore, the ferronickel ion-containing solution obtained by the leaching step and the solid residue can be easily separated by filtration and can be separated by a solid-liquid separator such as a filter press or a decanter to obtain a ferronickel ion-containing solution .

Next, a step of precipitating nickel and iron ions is carried out. The precipitation of nickel and iron ions can be carried out by introducing a reducing raw material. In order to distinguish the reducing raw materials from the reducing raw materials used for the leaching reaction for the precipitation reaction used in the precipitation reaction, they are referred to as precipitation reducing raw materials and leaching reducing raw materials, respectively.

When the precipitation reducing raw material is charged into the nickel and iron ion-containing solution, the dissolved nickel is replaced with Fe of the precipitation reducing raw material. As a result, nickel is precipitated as ferronickel from the nickel and iron containing solution. In the present invention, the ferronickel-containing ferronickel cake may be introduced into an AOD refining furnace to be used as nickel and iron source.

Hereinafter, the present invention will be described more specifically by way of specific examples. The following examples are provided to aid understanding of the present invention, and the scope of the present invention is not limited thereto.

(Example)

Example 1

The ferronickel in the oxide state having the composition shown in Table 1 was molded at a high temperature to prepare a ferronickel cake, which was then charged into stainless steel (SUS 304 molten steel) at a temperature of 1550 ° C maintained in the AOD refining furnace.

The AOD refining furnace contained 100 tons of molten steel, and the amount of ferronickel cake was 2 tons, corresponding to 2% of the weight of molten steel. The loading time of the ferronickel cake was adjusted immediately after the molten metal was charged into the refining furnace, and the time point at which decarburization could be performed thereafter. Further, the reducing unit was started after 40 minutes from charging, and the molten steel was reduced in the ferrous metal such as Ni and Fe in the reducing unit. At this time, the reduction degree of slag was controlled by controlling the basicity of the slag, and as a result, the rapid increase of S component into the molten steel was not confirmed. The molten steel temperature at the time of charging was maintained at 1700 캜.

A sample of molten steel was collected before and after charging the ferronickel cake, and the change in Ni content in the molten steel was measured. As a result, it was confirmed that the Ni content after charging was 6.67% (when only ferronickel cake was charged), the Ni content was increased by about 0.17% by weight, compared with 6.5% by weight before charging. The recovery rate of Ni in the nickel cake was 95% or more, and it was confirmed that when the ferronickel cake was put into the AOD, it could sufficiently perform its role as a Ni source.

In this way, when the ferronickel cake is directly introduced into the AOD (entering the plant), not only the energy cost for the SAF treatment but also the feed cost for the raw material can be reduced.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It will be obvious to those of ordinary skill in the art.

Claims (12)

Preparing a ferronickel cake containing ferronickel in an oxide state;
Introducing a ferronickel cake containing ferronickel in the oxide state into an AOD refining furnace; And
And recovering nickel and iron into molten steel by reducing the ferronickel cake.
The method of producing a nickel-containing steel according to claim 1, wherein the ferronickel cake is formed by mixing ferronickel oxide in the form of a mixture of at least one of a binder and a reducing agent or ferronickel in the form of oxide at a high temperature.
3. The method of claim 2, wherein the binder is a mixture of an organic binder and an inorganic binder.
3. The method according to claim 2, wherein the reducing agent is one or a mixture of two or more selected from cokes, Fe-Si and aluminum.
The process according to claim 1, wherein the ferronickel in the oxide state comprises 9 to 12% by weight of nickel and 35 to 40% by weight of iron.
The method according to claim 1, wherein the oxide state ferronickel
A slurrying step of slurring the reduced light for leaching of the reduced nickel ore;
A leaching step of adding hydrochloric acid or sulfuric acid to the slurry to dissolve nickel and iron from the leaching reduction light to produce an immersion liquid; And
Adding a reducing light for precipitation of nickel ore reduced with a hydrogen-containing gas to the leaching solution in an amount of 10 to 40% by weight based on the total weight of the leaching reduction light and the precipitation reducing light to form nickel of the leaching solution Wherein the ferronickel cake is in the form of an oxide obtained by a step of replacing the ion.
The method of producing a nickel-containing steel according to claim 1, wherein the ferronickel cake is charged at 5% or less based on the weight of the molten steel before charging.
The method according to claim 1, wherein the step of introducing the ferronickel cake into the AOD refining furnace is performed prior to the reducing unit.
The method of manufacturing a nickel-containing steel according to claim 1, wherein the step of introducing the ferronickel cake into the AOD refining furnace is performed in a decarburizer.
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