JP7215092B2 - Method for smelting oxide ore - Google Patents

Description

TECHNICAL FIELD The present invention relates to a smelting method for oxide ore, and for example, to a smelting method for obtaining a reduced product by reducing oxide ore such as nickel oxide ore as a raw material with a carbonaceous reducing agent.

As a smelting method for nickel oxide ore called limonite or saprolite, which is a kind of oxide ore, a pyrometallurgical method that uses a smelting furnace to produce nickel matte, a rotary kiln or a moving hearth furnace that uses iron and nickel A pyrometallurgical refining method to produce an alloy of iron and nickel (an alloy of iron and nickel is hereinafter referred to as "ferronickel"). ) are known.

Among the various methods described above, when the nickel oxide ore is reduced and smelted using the pyrometallurgical method, the raw material nickel oxide ore is crushed to an appropriate size in order to proceed with the reaction. Agglomeration processing is performed as a pretreatment.

Specifically, when the nickel oxide ore is agglomerated, that is, when powdery or fine-grained ore is agglomerated, the nickel oxide ore and other components such as a binder and a reducing agent such as coke are mixed. After adjusting the moisture content, etc., the mixture is charged into a lump manufacturing machine, for example, a molded product (pellets, briquettes, etc.) having a side or a diameter of about 10 mm or more and 30 mm or less. Hereinafter, simply “pellets” It is common to assume that

Pellets obtained by agglomeration require a certain degree of air permeability in order to "fly off" the contained moisture. Furthermore, in the subsequent reduction treatment, if the reduction does not proceed uniformly within the pellet, the composition of the resulting reduced product becomes non-uniform, causing problems such as dispersion or uneven distribution of the metal. Therefore, it is important to uniformly mix the mixture when producing pellets, and to maintain as uniform a temperature as possible when reducing the obtained pellets.

In addition, coarsening the metal (ferronickel) produced by the reduction treatment is also a very important technique. If the generated ferronickel has a fine size of, for example, several tens of micrometers or more and several hundred micrometers or less, it becomes difficult to separate it from the slag that is generated at the same time, and the recovery rate (yield) as ferronickel is greatly reduced. put away. Therefore, a treatment for coarsening ferronickel after reduction is required.

For example, in Patent Document 1, an agglomerate containing a metal oxide and a carbonaceous reducing agent is supplied onto the hearth of a moving bed type reduction melting furnace and heated to reduce and melt the metal oxide. In the manufacturing method, when the relative value of the projected area ratio of the agglomerate to the hearth with respect to the maximum projected area ratio of the agglomerate to the hearth when the distance between the agglomerates is 0 is taken as the laying density , a method of supplying agglomerates having an average diameter of 19.5 mm or more and 32 mm or less onto a hearth so as to have a bed density of 0.5 or more and 0.8 or less and heating them. It is described that in this method, the productivity of granular metallic iron can be increased by controlling both the bed density and the average diameter of the agglomerate.

However, when the diameter of the agglomerate is limited to a predetermined range as in the technique described in Patent Document 1, a decrease in yield when producing the agglomerate is unavoidable, resulting in cost I am worried about going up. When the laying density of the agglomerate is in the range of 0.5 or more and 0.8 or less, it is difficult to laminate the agglomerate in addition to the close packing, resulting in a low efficiency treatment.

As described above, when nickel oxide ore is mixed and reduced to produce a metal containing nickel and iron, it is important to increase productivity, reduce costs, and improve quality. Despite this, there were many problems.

JP 2011-256414 A

The present invention is a smelting method for producing metal by reducing a mixture containing oxide ore such as nickel oxide ore, which can increase the grade of the obtained metal and efficiently produce high-quality metal. An object of the present invention is to provide a method for smelting oxide ore.

The inventors of the present invention have found that the above problems can be solved by deoxidizing the flame of the burner in a method of performing heat reduction treatment using a burner in a reducing furnace, and have completed the present invention. reached.

(1) The first aspect of the present invention is a mixing step of obtaining a mixture containing an oxide ore and a carbonaceous reducing agent, charging the obtained mixture into a reducing furnace, and deoxidizing the flame ejected from the burner. and a reduction step of subjecting the mixture to a heat reduction treatment with a flame after the deoxidation treatment.

(2) A second aspect of the present invention is the method for smelting oxide ore according to the first aspect, wherein in the reduction step, deoxidation treatment is performed in the vicinity of the flame ejected from the burner.

(3) A third aspect of the present invention is a method for smelting an oxide ore according to the second aspect, wherein, in the reducing step, a deoxidizing agent is placed near the flame ejected from the burner to perform deoxidizing treatment. .

(4) In the fourth aspect of the present invention, in the second aspect, a dosing facility is installed in a predetermined range from the tip of the flame ejection hole of the burner, and an oxygen scavenger is directed from the dosing facility toward the flame of the burner. It is a smelting method of oxide ore that deoxidizes by throwing in.

(5) A fifth aspect of the present invention is a method for smelting oxide ore, wherein the deoxidizing agent is a carbonaceous reducing agent in any one of the second to fourth aspects.

(6) In a sixth aspect of the present invention, in any one of the first to fifth aspects, in the reduction step, the oxygen concentration in the reduction furnace after the heat reduction treatment is 0.5% by volume or less. It is a method of smelting oxide ore that

(7) A seventh aspect of the present invention is the method for smelting oxide ore according to any one of the first to sixth aspects, wherein the oxide ore is nickel oxide ore.

According to the method for smelting oxide ore according to the present invention, high-quality metal can be efficiently produced.

BRIEF DESCRIPTION OF THE DRAWINGS It is process drawing which shows an example of the flow of the smelting method of a nickel oxide ore. FIG. 2 is a diagram for explaining an embodiment of deoxidizing the flame of a burner in a reducing furnace, and is a cross-sectional view of the reducing furnace including a structure for deoxidizing. FIG. 2 is a diagram for explaining an embodiment of deoxidizing the flame of a burner in a reducing furnace, and is a cross-sectional view of the reducing furnace including a structure for deoxidizing.

Specific embodiments of the present invention will be described in detail below. In addition, the present invention is not limited to the following embodiments, and various modifications are possible without changing the gist of the present invention. Further, in this specification, the notation "X to Y" (X and Y are arbitrary numerical values) means "X or more and Y or less".

≪1. Outline of smelting method for oxide ore≫
In the method for smelting oxide ore according to the present embodiment, oxide ore (oxide), which is a raw material ore, is mixed with a carbonaceous reducing agent, and the mixture (pellets) is placed in a smelting furnace (reducing furnace). Metal and slag are generated by performing a reduction treatment.

For example, as the oxide ore, a nickel oxide ore containing nickel oxide, iron oxide, or the like is used as a raw material, and the nickel oxide ore and a carbonaceous reducing agent are mixed to obtain a mixture, and nickel contained in the mixture is preferentially used. reduction and partial reduction of iron to produce ferronickel, which is an alloy of iron and nickel.

Then, in the method for smelting oxide ore according to the present embodiment, a heat reduction treatment method using a burner in a reduction furnace is adopted, and at that time, the flame of the burner is deoxidized to It is characterized by subjecting a mixture containing nickel oxide ore to a heat reduction treatment with a flame after the treatment.

According to such a method, it is possible to suppress the oxidation of the reduced product by the oxygen contained in the flame of the burner, and improve the quality of the obtained metal.

≪2. Smelting method for producing ferronickel using nickel oxide ore>>
In the following, nickel (nickel oxide) and iron (iron oxide) contained in nickel oxide ore, which is the raw material ore, are reduced to produce iron-nickel alloy metals, and then the metals are separated into ferromagnetic A smelting method for producing nickel will be described as an example.

Specifically, as shown in FIG. 1, the nickel oxide ore smelting method according to the present embodiment includes a mixing step S1 in which a nickel oxide ore and a carbonaceous reducing agent are mixed to obtain a mixture; It includes a reduction step S2 in which the mixture is subjected to reduction treatment, and a separation step S3 in which metal and slag are separated from the reduced product.

<2-1. Mixing process>
The mixing step S1 is a step of mixing a nickel oxide ore and a carbonaceous reducing agent as a reducing agent to obtain a mixture. Specifically, in the mixing step S1, first, a carbonaceous reducing agent, which is a first reducing agent, is added to and mixed with a nickel oxide ore, which is a raw material ore. Components, binders, and the like, for example, powders having a particle size of about 0.1 mm to 0.8 mm are added and mixed to obtain a mixture. The mixing treatment can be performed using a mixer or the like.

The nickel oxide ore, which is the raw material ore, is not particularly limited, but limonite ore, saprolite ore, and the like can be used. The nickel oxide ore contains at least nickel oxide (NiO) and iron oxide (Fe ₂ O ₃ ).

Examples of the carbonaceous reducing agent include, but are not particularly limited to, coal powder, coke powder, and the like. It is preferable that the carbonaceous reducing agent has the same particle size and particle size distribution as the nickel oxide ore, which is the raw material ore, because it is easily mixed uniformly and the reduction reaction proceeds uniformly.

The content of the carbonaceous reducing agent (the content of the carbonaceous reducing agent contained in the mixture) includes the chemical equivalent required to reduce the total amount of nickel oxide constituting the nickel oxide ore to nickel metal, and iron oxide ( Ferric oxide) and the chemical equivalent required to reduce to metallic iron (for convenience, also referred to as "total chemical equivalent") is 100% by mass, 50% by mass or less It is preferable to set it as a ratio, and it is more preferable to set it as a ratio of 40% by mass or less. The amount of iron to be reduced can be suppressed, the nickel grade can be improved, and high-quality ferronickel can be produced. The amount of the carbonaceous reducing agent mixed is preferably 10% by mass or more, more preferably 15% by mass or more, when the total chemical equivalent is 100% by mass. Nickel reduction can be efficiently advanced, and productivity is improved.

As iron ore, which is an optional component additive, for example, iron ore having an iron grade of about 50% by mass or more, hematite obtained by hydrometallurgical refining of nickel oxide ore, and the like can be used. Examples of flux components include calcium oxide, calcium hydroxide, calcium carbonate, and silicon dioxide. Examples of binders include bentonite, polysaccharides, resins, water glass, and dehydrated cakes.

In the mixing step S1, a mixture is obtained by uniformly mixing raw material powders containing nickel oxide ore. Table 1 below shows an example of the composition (% by mass) of some of the raw material powders mixed in the mixing step S1, but the composition of the raw material powder is not limited to this.

At the time of mixing, kneading may be carried out at the same time in order to improve mixability, or kneading may be carried out after mixing. Kneading can be performed using a batch type kneader such as Brabender, Banbury mixer, Henschel mixer, helical rotor, roll, single-screw kneader, twin-screw kneader, or the like. By kneading the mixture, a shearing force is applied to the mixture, and the agglomeration of the carbonaceous reducing agent, the raw material powder, etc. can be released and uniformly mixed, and the adhesion of each particle can be improved, and the voids can be reduced. can be done. As a result, the reduction reaction can easily occur in the mixture, and the reaction can be performed uniformly, and the reaction time for the reduction reaction can be shortened. In addition, it is possible to suppress variations in quality.

Alternatively, after mixing, or after mixing and kneading, extrusion may be performed using an extruder. As a result, pressure (shearing force) is applied to the mixture, and the aggregation of the carbonaceous reducing agent, the raw material powder, etc. is released, and the mixture can be mixed more uniformly. Additionally, voids within the mixture can be reduced. For these reasons, the reduction reaction of the mixture is more likely to occur uniformly in the reduction step S2, which will be described later, and the quality of the obtained metal can be improved, so that a high-quality metal can be produced.

The extruder is preferably one capable of kneading and molding the mixture under high pressure and high shear force, and examples thereof include a single-screw extruder and a twin-screw extruder. In particular, it is preferable to have a twin-screw extruder. By kneading the mixture under high pressure and high shear, the agglomeration of the mixture of raw material powders can be broken off, the mixture can be kneaded effectively, and the strength of the mixture can be increased. Moreover, by using a machine equipped with a twin-screw extruder, a mixture can be obtained continuously while maintaining high productivity.

Alternatively, the mixture may be molded into a molded product (pellet) having a predetermined shape. The shape of the molding can be, for example, a spherical shape, a rectangular parallelepiped shape, a cubic shape, a cylindrical shape, or the like. Since such a shape is simple and not complicated, it is possible to suppress the occurrence of defective products while suppressing the molding cost, and the quality of the obtained molded product is uniform, suppressing the decrease in yield. can do.

The shape of the molding is particularly preferably spherical. Since the spheroidal molding is used, the reduction treatment can be performed uniformly, and smelting can be performed with little variation and high productivity. When the shape of the molded product is spherical, it can be molded to have a diameter of about 10 mm or more and 30 mm or less. In the case of a rectangular parallelepiped, cubic, columnar shape, etc., the shape can be generally formed so that the internal dimensions in length and width are about 500 mm or less.

The size of the molded product is not particularly limited, but the volume of the molded product is preferably 8000 mm ³ or more. Since the volume of the molded product is 8000 mm ³ or more, the molding cost is suppressed, and the ratio of the surface area to the entire molded product is low, so the reduction treatment is uniformly performed, the variation is small, and the productivity is improved. Can perform high smelting.

Also, the obtained mixture may be filled into a predetermined container for reduction. By subjecting the mixture filled in the container to the reduction treatment while the mixture is still filled in the container, the metal reduced in the separation step S3 described later can be easily separated and recovered by a treatment such as magnetic separation, and loss can be reduced. can be suppressed.

In the mixing step S1, the obtained mixture may be subjected to drying treatment. The mixture is mixed with a large amount of water in kneading, molding of moldings, or the like. Although it is not an essential aspect to perform the drying treatment in the present embodiment, by performing the drying treatment on the mixture containing a large amount of water, it is possible to prevent the expansion of the mixture due to the evaporation of water in the reduction treatment described later. .

Furthermore, by subjecting the mixture to a drying treatment, it is possible to suppress contamination of water due to the mixture in the reduction furnace. As a result, the amount of water contained in the atmospheric gas in the reducing furnace can be more effectively reduced, and the oxidation of metals contained in the reduced product can be more effectively suppressed.

The method of drying the mixture is not particularly limited, and includes a method of maintaining the mixture at a predetermined drying temperature (for example, 300° C. or more and 400° C. or less), a method of blowing hot air at a predetermined drying temperature to the mixture, and the like. , conventionally known means can be used. By such drying treatment, for example, the solid content of the mixture is about 70% by mass and the water content is about 30% by mass. The temperature of the mixture itself during this drying treatment is preferably less than 100° C., which can prevent the mixture from bursting due to bumping of moisture or the like.

Moreover, the drying treatment may be continuously performed at once or may be performed in multiple steps. Explosion of the mixture can be more effectively suppressed by performing the drying treatment in multiple steps. In addition, when the drying treatment is performed in a plurality of times, the drying temperature for the second and subsequent times is preferably 150° C. or higher and 400° C. or lower. By drying in this range, it becomes possible to dry without progressing the reduction reaction.

Table 2 below shows an example of the solid content composition (parts by mass) of the mixture after drying. In addition, the composition of the molding is not limited to this.

<2-2. Reduction process>
The reduction step S2 is a step of charging the obtained mixture into a reduction furnace and subjecting the mixture to a reduction treatment to obtain a reduced product containing metal and slag. By the reduction treatment in the reduction step S2, a smelting reaction (reduction reaction) proceeds based on the carbonaceous reducing agent in the mixture, and in the mixture, ferronickel metal (hereinafter simply referred to as “metal”) and ferronickel Slag (hereinafter simply referred to as "slag") is generated separately.

Specifically, in the reduction step S2, a reduction furnace equipped with a burner is used, and the burner heats the material to a predetermined reduction temperature for reduction treatment.

In the reduction treatment, the nickel oxide ore and iron oxide in the mixture are reduced and metallized in the vicinity of the surface of the mixture where the reduction reaction is likely to proceed, for a short period of time, for example about 1 minute, to form a shell. Form. On the other hand, in the shell, the slag components are gradually melted as the shell is formed to form liquid phase slag. As a result, metal and slag are separated from each other in the mixture.

Then, after about 10 minutes of treatment time, excess carbonaceous reducing agent that does not participate in the reduction reaction is incorporated into the metal, lowering the melting point of the metal and turning the metal into a liquid phase.

The temperature (reduction temperature) in the reduction treatment is not particularly limited, but is preferably in the range of 1200° C. or higher and 1450° C. or lower, and more preferably in the range of 1300° C. or higher and 1400° C. or lower. By performing the reduction within such a temperature range, the reduction reaction can be uniformly induced, and ferronickel with suppressed variations in quality can be produced. Moreover, the desired reduction reaction can be caused in a relatively short period of time by reducing at a reduction temperature in the range of more preferably 1300° C. or higher and 1400° C. or lower.

The time (treatment time) in the reduction treatment is set according to the temperature of the reducing furnace, and is preferably 10 minutes or longer, more preferably 15 minutes or longer.

The amount of heat required for the reduction obtained by multiplying the values of the reduction temperature (°C) and the reduction time (minutes) is preferably in the range of 20000 (°C x minutes) to 40000 (°C x minutes). High quality metal can be efficiently manufactured.

Conventionally, as one method of smelting oxide ore, a method of performing a reduction treatment by heating using a burner in a reduction furnace has been adopted. By heating with a burner, reduction treatment can be performed by heating with less energy, making it possible to perform efficient smelting operations. As fuel for the burner, for example, LPG gas (liquefied petroleum gas), LNG gas (natural gas), coal, coke, pulverized coal, or the like can be used. The cost of these fuels is very low, and equipment costs and maintenance costs can be remarkably reduced compared to electric furnaces and the like.

Now, in the reduction treatment using a burner for heating, in order to avoid incomplete combustion of the burner, the burner is heated by supplying an excessive amount of air together with the fuel. However, in such a case, since unreacted oxygen is included in the flame of the burner, when the mixture is subjected to heat reduction treatment with such a flame, the reduction reaction is inhibited. There is a problem that part of the generated metal is oxidized again by the oxygen.

Therefore, in the nickel oxide ore smelting method according to the present embodiment, in performing the reduction treatment by heating using the burner, the flame of the burner is deoxidized, and the flame after the deoxidization treatment deoxidizes the mixture. Characterized by heating. By deoxygenating the burner flame in this way, it is possible to suppress the inflow of unreacted oxygen into the space where the reduction treatment is to be carried out, thereby oxidizing part of the generated metal. can be prevented.

Here, it is important to perform the deoxidation treatment in the vicinity of the flame of the burner. By performing deoxygenation treatment near the flame, oxygen contained in the flame can be prevented from flowing into the mixture in the reduction furnace. This can prevent the reduction reaction of the mixture from being inhibited and part of the generated metal from being oxidized.

Furthermore, the position of the deoxidation treatment is preferably near the tip of the burner flame. This is because the tip of the flame of the burner is the most heated, and the generated heat can be used to accelerate the deoxidation reaction. As a result, it is possible to more effectively remove unreacted oxygen in the flame of the burner, and to more appropriately suppress the inflow of oxygen into the space where reduction treatment is performed in the reduction furnace.

As a method of deoxidizing the burner flame, a treatment using a deoxidizing agent can be mentioned. In the treatment with an oxygen scavenger, for example, oxygen in the flame is removed by contacting the burner flame with the oxygen scavenger.

FIG. 2 is a diagram for explaining a specific embodiment (an example of deoxidizing treatment using a deoxidizing agent) in which the flame of a burner is deoxidized in a reducing furnace. 1 is a cross-sectional view of a reducing furnace including the configuration of . As shown in FIG. 2 , in the reduction furnace 1 , the oxygen scavenger 11 is arranged on the mounting table 12 within a predetermined range from the flame ejection holes 10 s of the burner 10 . In such a reducing furnace 1, the flame 10f ejected from the burner 10 comes into contact with the oxygen scavenger 11 arranged in a predetermined range from the flame ejection hole 10s, and reacts with unreacted oxygen in the flame 10f. This removes (deoxygenates) unreacted oxygen in the flame 10f. By heating the mixture P placed on the hearth 13 in the reducing furnace 1 using the burner flame after such deoxidizing treatment, unreacted oxygen is reduced in the reducing furnace 1. Inflow into the space 1r can be suppressed, and the mixture P can be appropriately reduced.

Further, FIG. 3 is a diagram for explaining another example of the manner in which the flame of the burner is deoxidized in the reducing furnace. In the example shown in FIG. 3, in the reducing furnace 2, the powdery deoxidizing agent 21 is ejected toward the flame 20f of the burner 20 to perform the deoxidizing treatment. More specifically, the reducing furnace 2 is provided with a dosing facility 22 above the ejection space of the flame 20f from the burner 20, and the powdery desorption from this dosing facility 22 toward the flame 20f of the burner 20. It is configured such that an oxygen agent 21 is injected. In such a reducing furnace 2, the flame 20f ejected from the burner 20 comes into contact with the oxygen scavenger 21 thrown toward the flame 20f and reacts with unreacted oxygen in the flame 20f. As a result, unreacted oxygen in the flame 20f is removed (deoxygenated). By heating the mixture P placed on the hearth 23 in the reducing furnace 2 using the burner flame after such deoxidizing treatment, unreacted oxygen is reduced in the reducing furnace 2. Inflow into the space 2r can be suppressed, and the mixture P can be appropriately reduced.

In the deoxidizing treatment using a deoxidizing agent, the deoxidizing agent is not particularly limited as long as it can remove (deoxidize) unreacted oxygen in the flame. For example, a carbonaceous reducing agent can be used. can. When a carbonaceous reducing agent is used as the oxygen scavenger, unreacted oxygen in the flame reacts with carbon contained in the carbonaceous reducing agent, and the oxygen is replaced with carbon monoxide or carbon dioxide, resulting in a flame. It becomes possible to effectively remove the unreacted oxygen inside.

Examples of carbonaceous reducing agents as oxygen scavengers include coal powder and coke powder. The same carbonaceous reducing agent as that contained in the mixture to be reduced may be used, or a different one may be used.

The oxygen scavenger is not limited to the carbonaceous reducing agent, and may be, for example, sulfite, hydrogen sulfite, thiosulfate, iron powder, or the like.

2 and 3, an example of the deoxidizing process using a deoxidizing agent was shown and explained, but the deoxidizing treatment is not limited to using the deoxidizing agent. For example, by installing a filter that adsorbs oxygen at a predetermined position in the flame ejection space in the reduction furnace, even if the burner flame is deoxygenated when passing through the filter. good.

In this way, the flame of the burner is deoxidized, and the mixture is heated by the flame after the deoxidation treatment to be reduced, so that unreacted oxygen flows into the reduction treatment space. In addition, naturally, the amount of oxygen remaining in the reduction furnace after the reduction treatment can be effectively reduced, and the quality of the obtained metal can be improved. Specifically, the reduction treatment can be performed so that the oxygen concentration in the reduction furnace after the reduction treatment is 0.5% by volume or less. Moreover, it is more preferable to carry out the reduction treatment so that the oxygen concentration in the reduction furnace is 0.3% by volume or less. Here, since the oxygen concentration in the reduction furnace after the reduction treatment depends on the degree of deoxidation treatment for the burner flame, it can be adjusted by the amount of air and deoxidizer supplied to the burner.

<2-3. Separation process>
The separation step S3 is a step of separating metal and slag from the reduced product obtained in the reduction step S2. Specifically, the metal phase is separated and recovered from the mixture (mixture) containing the metal phase and the slag phase obtained by the reduction heat treatment of the mixture filled in the container.

Methods for separating the metal phase and the slag phase from the mixture of the metal phase and the slag phase obtained as a solid include, for example, in addition to removing unnecessary substances by sieving, separation by specific gravity, separation by magnetic force, etc. method can be used.

In addition, the obtained metal phase and slag phase can be easily separated from each other due to their poor wettability. Alternatively, the metal phase and the slag phase can be easily separated from the mixture by applying an impact such as giving a predetermined vibration during sieving.

By separating the metal phase and the slag phase in this way, the metal is recovered.

EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

<Example 1, Comparative Example 1>
Nickel oxide ore as raw material ore, iron ore, silica sand and limestone as flux components, binder, and carbonaceous reducing agent (coal powder, carbon content: 85% by mass, average particle size: about 75 μm) are mixed in appropriate amounts. of water was added and mixed using a mixer to obtain a mixture. The amount of the carbonaceous reducing agent (coal powder) is 100% by mass, which is the amount necessary to reduce nickel oxide and iron oxide (Fe ₂ O ₃ ) contained in the nickel oxide ore, which is the raw material ore, in just the right amount. was contained in an amount that would be a proportion of 28% by mass. The resulting mixture was then equally divided into 14 samples.

Next, with a pan-type granulator, 14 mixtures (samples) with a diameter of 15.0 ± 0.5 mm were formed into spheres by adding water as appropriate to the mixture obtained (Examples 1-1 to 1- 12, Comparative Examples 1-1 and 1-2) were obtained.

Next, the mixtures (samples) of Examples 1-1 to 1-12 were charged into a reducing furnace, and oxygen scavenger (coal powder) was supplied in the amount shown in Table 3 near the tip of the flame ejected from the burner. deoxygenated the burner flame by arranging the Then, the mixture (sample) was heat-reduced by the flame after the deoxidizing treatment (in Table 3, "deoxidizing treatment" is indicated as "yes"). In addition, the "supply amount (% by mass) of oxygen scavenger" in Table 3 means that the chemical equivalent of the oxygen scavenger required to react all the surplus oxygen supplied to the burner is 100% by mass. means the value of

On the other hand, the samples of Comparative Examples 1-1 and 1-2 were charged into a reducing furnace, and the mixture (sample) was heated and reduced without deoxidizing the burner flame. (In Table 3, "deoxygenation treatment" is indicated as "none").

In the reduction treatment, the hearth of the reduction furnace is preliminarily covered with a hearth protective agent (mainly composed of _{SiO2 ,} and containing a small amount of oxides such as _Al2O3 and MgO as other components). A sample was placed thereon and subjected to a reduction treatment.

After such a reduction treatment, the samples of Examples 1-1 to 1-12 and Comparative Examples 1-1 and 1-2 after the cooling of the resulting reduced material were pulverized, and then the metal was recovered by magnetic separation.

For each sample after the reduction heat treatment, the nickel metallization rate, the nickel content rate in the metal, and the metal recovery rate were analyzed and calculated using an ICP emission spectrometer (SHIMAZU S-8100 type).

The nickel metallization rate, nickel content rate in metal, and nickel metal recovery rate were calculated by the following equations (1), (2), and (3).
Nickel metallization rate = mass of nickel in metal/(mass of all nickel in reduced product) x 100 (%) (1) formula Nickel content in metal = mass of nickel in metal/(metal Total mass of nickel and iron in the inside) × 100 (%) (2) formula Nickel metal recovery rate = amount of nickel recovered / (amount of ore charged × content of nickel in ore) × 100・・(3) formula

Table 3 below shows the oxygen concentration in the reducing furnace after the heat reduction treatment, the nickel metallization rate, the nickel content in the metal, and the nickel metal recovery rate for each sample.

As can be seen from the results in Table 3, the burner flame was deoxidized by placing a deoxidizing agent (coal powder) near the tip of the flame ejected from the burner. In Examples 1-1 to 1-12 in which heat reduction treatment was performed, the nickel metallization ratio, the nickel content in the metal, and the nickel recovery ratio were all higher than those in Comparative Examples 1-1 and 1-2. .

<Example 2>
As in Example 1 and Comparative Example 1, nickel oxide ore, iron ore, silica sand and limestone as flux components, binder, and carbonaceous reducing agent (coal powder, carbon content: 85% by mass, average particle diameter: about 75 μm) were mixed using a mixer while adding an appropriate amount of water to obtain a mixture. The amount of the carbonaceous reducing agent (coal powder) is 100% by mass, which is the amount necessary to reduce nickel oxide and iron oxide (Fe ₂ O ₃ ) contained in the nickel oxide ore, which is the raw material ore, in just the right amount. was contained in an amount that would be a proportion of 28% by mass.

Next, 12 spherically shaped mixtures (samples) with a diameter of 15.0 ± 0.5 mm were prepared by adding water as appropriate to the resulting mixture and using a pan-type granulator (Example 2- 1-2-12) obtained.

Next, the mixtures (samples) of Examples 2-1 to 2-12 were charged into a reducing furnace, and powdered oxygen scavengers (carbonaceous reductants) were supplied in amounts shown in Table 4 from the dosing equipment. was thrown near the tip of the flame ejected from the burner to deoxidize the flame of the burner. Then, the mixture (sample) was heat-reduced by the flame after the deoxidizing treatment (in Table 3, "deoxidizing treatment" is indicated as "yes"). The "supply amount (% by mass) of oxygen scavenger" in Table 4 is the value when the chemical equivalent of the oxygen scavenger required to react all the surplus oxygen supplied to the burner is 100% by mass. means The dosing equipment is installed above the burner 20 in the reducing furnace, as shown in FIG. was thrown near the tip of the

In the reduction treatment, the hearth of the reduction furnace is preliminarily covered with a hearth protective agent (mainly composed of _{SiO2 ,} and containing a small amount of oxides such as _Al2O3 and MgO as other components). A sample was placed thereon and subjected to a reduction treatment.

After such a reduction treatment, the samples of Examples 2-1 to 2-12 obtained after cooling the reduced product were pulverized, and then the metal was recovered by magnetic separation.

As can be seen from the results in Table 4, the burner flame was deoxygenated by throwing a powdery decarbonizing agent from the dosing equipment, and the flame after the deoxygenation treatment was subjected to heat reduction treatment. In Examples 2-1 to 2-12, compared with Comparative Examples 1-1 and 1-2 in Table 3, the nickel metallization rate, the nickel content rate in the metal, and the nickel recovery rate were all higher.

Reference Signs List 1, 2 reducing furnace 10, 20 burner 10s, 20s flame vent 10f, 20f flame 11, 21 oxygen absorber 12 installation table 22 dosing equipment 13, 23 hearth P mixture 1r, 2r space for reduction treatment

Claims (4)

a mixing step of obtaining a mixture containing a nickel oxide ore and a carbonaceous reducing agent;
The obtained mixture is charged into a reducing furnace equipped with a burner, the flame ejected from the burner is subjected to deoxidizing treatment, and the mixture is subjected to heat reduction treatment by the flame after the deoxidizing treatment. A reduction step of obtaining a reduced product such that the oxygen concentration in the reduction furnace after the heat reduction treatment is 0.5% by volume or less ;
a separation step of cooling the obtained reduced product and separating nickel metal and slag from the cooled reduced product;
including
A method for smelting nickel oxide ore. 2. The nickel oxidation according to claim 1 , wherein, in the reducing step, the deoxidizing agent is arranged so that the flame ejected from the burner and the deoxidizing agent are in contact with each other, so that the flame is deoxidized. A method of smelting ore. 2. The method for smelting nickel oxide ore according to claim 1 , wherein, in the reduction step, a deoxidizing treatment is performed by throwing a deoxidizing agent from a dosing facility toward the flame of the burner. The method for smelting nickel oxide ore according to claim 2 or 3 , wherein the oxygen scavenger is a carbonaceous reducing agent.

Images