JP2018197382A - Method for smelting oxide ore - Google Patents

Abstract

To provide a method for smelting an oxide ore where a high-quality metal can be produced with high productivity or efficiency and at a low production cost.SOLUTION: Provided is a method for smelting an oxide ore to produce a metal or an alloy by heating and reducing a mixture containing the oxide ore and a carbonaceous reducing agent, where the carbonaceous reducing agent is composed of reducing agent particles 1. For the reducing agent particles 1, an average volume rate of reducing agent particles is 5-80%, and the average maximum particle length is 5-500 μm. An average volume rate of the reducing agent particles=total of volume rates of 300 reducing agent particles/300, a volume rate of the reducing agent particles=(volume of reducing agent particles/volume of sphere C with maximum particle length D of reducing agent particles as the diameter)×100, an average maximum particle length=total of maximum particle length D of the 300 reducing agent particles/300).SELECTED DRAWING: Figure 2

Description

  The present invention relates to a method for smelting oxide ore, for example, smelting by reducing and heating pellets produced from an oxide ore such as nickel oxide ore and a reducing agent at a high temperature in a reduction furnace. And a smelting method for obtaining a reduced product such as ferronickel.

  As a smelting method of nickel oxide ore called limonite or saprolite which is a kind of oxide ore, dry smelting method to produce nickel matte using smelting furnace, iron and nickel using rotary kiln or moving hearth furnace Known are a dry smelting method for producing ferronickel, an alloy of the above, a hydrometallurgical method for producing mixed sulfide using an autoclave, and the like.

  Among the various methods described above, particularly when nickel oxide ore is reduced and smelted using dry smelting, the raw material nickel oxide ore is crushed to an appropriate size in order to proceed with the reaction. A process of forming a lump is performed as a pretreatment.

  Specifically, when nickel oxide ore is agglomerated, that is, when powdered or finely divided ore is agglomerated, the nickel oxide ore is mixed with other components such as binders and coke reducing agents. Then, after adjusting the moisture, etc., the mixture is charged into a lump manufacturing machine and, for example, indicates a lump (pellet, briquette, etc.) having a side or a diameter of about 10 mm to 30 mm. ).

  In order to “fly” away the moisture contained in the pellets obtained by agglomeration, a certain degree of air permeability is required. Further, if the reduction does not proceed uniformly in the pellet in the subsequent reduction treatment, the resulting reduced product has a non-uniform composition, resulting in inconveniences such as metal dispersion and uneven distribution. Therefore, it is important to uniformly mix the mixture when producing the pellets and to maintain the temperature as uniform as possible when reducing the obtained pellets.

  In addition, it is a very important technique to coarsen the metal (ferronickel) produced by the reduction treatment. When the produced ferronickel has a fine size of, for example, several tens of μm to several hundreds of μm, it becomes difficult to separate from the slag produced at the same time, and the recovery rate (yield) as ferronickel is greatly reduced. End up. Therefore, a process for coarsening the reduced ferronickel is required.

  In addition, how to reduce the smelting cost is an important technical matter, and a continuous process that can be operated with a compact facility is desired.

  For example, in Patent Document 1, an agglomerate containing a metal oxide and a carbonaceous reducing agent is supplied to a hearth of a moving bed type reduction melting furnace and heated to reduce and melt the metal oxide. In the production 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 used as the bed density A method is disclosed in which an agglomerate having an average diameter of 19.5 mm or more and 32 mm or less is supplied onto a hearth so that the bed density is 0.5 or more and 0.8 or less and heated. In this method, it is described in Patent Document 1 that the productivity of granular metallic iron can be enhanced by controlling the bed density and the average diameter of the agglomerates together.

  However, the method disclosed in Patent Document 1 is a technique for controlling a reaction occurring outside the agglomerate, and is a control of the reaction occurring inside the agglomerate, which is the most important factor in the reduction reaction. Is not focused on. On the other hand, by controlling the reaction that takes place inside the agglomerate, it has been demanded to obtain higher quality metals (metals, alloys) by increasing the reaction efficiency and promoting the reduction reaction more uniformly. .

  Moreover, since the method of using what has a specific diameter as an agglomerate like patent document 1 needs to remove what does not have a specific diameter, the yield at the time of producing an agglomerate is high. It was low. Further, in the method disclosed in Patent Document 1, it is necessary to adjust the bed density of the agglomerates to 0.5 or more and 0.8 or less, and the agglomerates cannot be laminated. It was. Thus, the method in Patent Document 1 has a high manufacturing cost.

  Furthermore, as in Patent Document 1, a process using a so-called total melting method in which all raw materials are melted and reduced has a large problem in terms of operation cost. For example, in order to completely melt the raw nickel oxide ore, it is necessary to raise the temperature to 1500 ° C. or higher. However, such a high temperature condition requires a large energy cost and is used at such a high temperature. Repairing furnaces are expensive because they are easily damaged. Furthermore, since the nickel oxide ore of the raw material contains only about 1% of nickel, it is not necessary to recover anything other than iron corresponding to the nickel, but even a large amount of components that are unnecessary to recover are included. Will melt everything, making it extremely inefficient.

  Therefore, reduction methods based on partial melting have been studied, in which only necessary nickel is reduced and iron contained much more than nickel is only partially reduced. However, in such a partial reduction method (or nickel preferential reduction method), the reduction reaction is carried out while maintaining the raw material in a semi-solid state that is not completely melted. It is not easy to control the reaction so that the reduction of iron remains in the range corresponding to nickel. As a result, there is a problem that partial variations occur in the reduction within the raw material, and that efficient operation is difficult such as a decrease in nickel recovery rate.

  In this way, the technology for producing metals and alloys by mixing and reducing oxide ore increases productivity and efficiency, reduces manufacturing costs, and promotes uniform reduction reactions to improve metal quality. There were many issues in that respect.

JP 2011-256414 A

  The present invention has been proposed in view of such circumstances, and in a smelting method for producing metal by reducing a mixture containing an oxide ore such as nickel oxide ore and a carbonaceous reducing agent, productivity is improved. Another object of the present invention is to provide a method capable of manufacturing a high-quality metal at a low manufacturing cost with high efficiency.

  This inventor repeated earnest examination in order to solve the subject mentioned above. As a result, the carbonaceous reducing agent is composed of particles (reducing agent particles), and the reducing agent particles have an average reducing agent particle volume ratio of 5% to 80% and an average maximum particle length of 5 μm to 500 μm. By using the following, it was found that the contact area between the oxide ore and the carbonaceous reducing agent and the uniformity of the mixture are increased, and thereby a uniform and highly efficient reduction reaction can be realized, leading to the present invention. It was. That is, the present invention provides the following.

(1) The first invention of the present invention is a smelting process in which an oxidized ore and a carbonaceous reducing agent are mixed, the resulting mixture is heated and subjected to a reduction treatment to obtain reduced metal and slag. An average reducing agent particle volume ratio determined by the following formulas (1) and (2) for the reducing agent particles using a method comprising particles (reducing agent particles) as the carbonaceous reducing agent. Is an smelting method of oxide ore in which the average maximum particle length determined by the following formula (3) is 5 μm or more and 500 μm or less.
Average reducing agent particle volume ratio = total of reducing agent particle volume ratio of 300 reducing agent particles / 300 (1)
Reducing agent particle volume ratio = (volume of reducing agent particle / volume of sphere having diameter of maximum particle length of reducing agent particle) × 100
... (2)
Average maximum particle length = the sum of the maximum particle lengths of 300 reducing agent particles / 300 (3)

  (2) The second invention of the present invention is the method for refining oxide ore according to the first invention, wherein the reduction temperature in the reduction treatment is 1200 ° C. or higher and 1450 ° C. or lower.

  (3) The third invention of the present invention is the method for refining oxide ore according to the first or second invention, wherein the oxide ore is nickel oxide ore.

  (4) A fourth invention of the present invention is the method of smelting ore oxide according to any one of the first to third inventions, wherein the metal is ferronickel.

  According to the present invention, in a smelting method for producing a metal by reducing a mixture containing an oxide ore and a carbonaceous reducing agent, a high-quality metal is produced with high productivity and efficiency and at a low production cost. Can be provided.

It is process drawing which shows an example of the flow of the smelting method of an oxide ore. It is a schematic diagram of a sphere having a maximum particle length of irregular particles and a diameter of the maximum particle length. It is a processing flow figure showing an example of the flow of processing in a reduction processing process. It is a figure (plan view) showing an example of composition of a rotary hearth furnace where a hearth rotates.

  Hereinafter, specific embodiments of the present invention will be described in detail. In addition, this invention is not limited to the following embodiment, A various change is possible in the range which does not change the summary of this invention. 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 the present invention >>
The method for smelting oxide ore according to the present invention comprises using an oxide ore as a raw material, mixing the oxide ore and a carbonaceous reducing agent into a mixture, and subjecting the resulting mixture to a reduction treatment at a high temperature to obtain a reduced product. It is the method of manufacturing the metal which is. For example, nickel oxide ore containing nickel oxide, iron oxide, etc. is used as a raw material, and the nickel oxide ore is mixed with a carbonaceous reducing agent, and nickel contained in the mixture is preferentially reduced at high temperatures. In addition, there is a method for producing ferronickel, which is an alloy of iron and nickel, by partially reducing iron.

Specifically, the method for smelting oxidized ore according to the present invention comprises mixing an oxidized ore and a carbonaceous reducing agent, heating the resulting mixture as a raw material, subjecting it to a reduction treatment, In the method for obtaining slag, the average reducing agent is composed of particles (hereinafter also referred to as “reducing agent particles”) as the carbonaceous reducing agent, and is obtained by the following formulas (1) and (2) for the reducing agent particles. A particle volume ratio is 5% or more and 80% or less, and an average maximum particle length obtained by the following formula (3) is 5 μm or more and 500 μm or less.
Average reducing agent particle volume ratio = total of reducing agent particle volume ratio of 300 reducing agent particles / 300 (1)
Reducing agent particle volume ratio = (volume of reducing agent particle / volume of sphere having diameter of maximum particle length of reducing agent particle) × 100
... (2)
Average maximum particle length = the sum of the maximum particle lengths of 300 reducing agent particles / 300 (3)

  According to such a smelting method, the contact area between the oxidized ore and the carbonaceous reducing agent can be increased, and the reduction reaction of the oxidized ore can be facilitated. In addition, since the dispersibility of the carbonaceous reducing agent in the mixture is increased, aggregation and uneven distribution of the carbonaceous reducing agent are suppressed, so that the reduction reaction can be promoted uniformly. As a result, high-quality metal can be manufactured with high productivity and efficiency and at a low manufacturing cost.

Hereinafter, as a specific embodiment of the present invention (hereinafter referred to as “the present embodiment”), a method for smelting nickel oxide ore will be described as an example. As described above, the nickel oxide ore that is a smelting raw material contains at least nickel oxide (NiO) and iron oxide (Fe ₂ O ₃ ), and the nickel oxide ore is reduced using the nickel oxide ore as a smelting raw material. By doing so, an iron-nickel alloy (ferronickel) can be manufactured as a metal.

  The present invention is not limited to nickel oxide ore as an oxide ore, and the smelting method is not limited to a method for producing ferronickel from nickel oxide ore containing nickel oxide or the like.

≪2. Nickel oxide ore smelting method >>
In the smelting method of nickel oxide ore according to the present embodiment, the nickel oxide ore is mixed with a carbonaceous reducing agent to form a mixture, and the mixture is subjected to a reduction treatment, whereby ferronickel that is a metal as a reduced product. And slag. In this smelting method, ferronickel is produced by preferentially reducing nickel (nickel oxide) in the mixture and partially reducing iron (iron oxide). In addition, the ferronickel which is a metal can be collect | recovered by isolate | separating the metal from the mixture containing the metal and slag obtained through the reduction process.

  FIG. 1 is a process diagram showing an example of the flow of a smelting method of nickel oxide ore. As shown in FIG. 1, this smelting method includes a mixing treatment step S1 in which nickel oxide ore and a carbonaceous reducing agent are mixed, and reduction charging in which the obtained mixture is agglomerated or filled into a predetermined container and molded. Pretreatment step S2, reduction treatment step S3 in which the mixture that has been agglomerated or filled in the container is heated at a predetermined temperature (reduction temperature), and a mixture (mixture) containing the metal and slag generated in the reduction treatment step S3 A separation step S4 for separating and recovering the metal from the product.

<1. Mixing process>
The mixing treatment step S1 is a step of obtaining a mixture by mixing raw material powders containing nickel oxide ore. Specifically, in the mixing treatment step S1, a carbonaceous reducing agent is added to and mixed with nickel oxide ore which is a raw material ore, and optional additives such as iron ore, flux components, binders, etc. Powder having a particle size of about 0.1 mm to 0.8 mm is added and mixed to obtain a mixture. The mixing process can be performed using a mixer or the like.

(Nickel oxide ore)
Although it does not specifically limit as a nickel oxide ore which is a raw material ore, Limonite ore, a saprolite ore, etc. can be used. The nickel oxide ore contains at least nickel oxide (NiO) and iron oxide (Fe ₂ O ₃ ).

(Carbonaceous reducing agent)
Although it does not specifically limit as a carbonaceous reducing agent, Coal powder, coke powder, etc. are mentioned.

  In the present embodiment, the carbonaceous reducing agent is composed of particles (reducing agent particles), the average reducing agent particle volume ratio for the reducing agent particles is 5% or more and 80% or less, and the average for the reducing agent particles. The maximum particle length is 5 μm or more and 500 μm or less. That is, this carbonaceous reducing agent has an average maximum particle length within a predetermined range and has a predetermined non-spherical shape. By satisfying such conditions, the carbonaceous reducing agent and the ore in the mixture can be well mixed and contacted. And a uniform reduction reaction is implement | achieved by using such a mixture, As a result, high quality ferronickel can be obtained.

  In particular, in this carbonaceous reducing agent, the average reducing agent particle volume ratio in the reducing agent particles is in the range of 5% to 80%. By using such a carbonaceous reductant, a sufficient contact area with the nickel oxide ore can be secured, and the carbonaceous reductant can be effectively used up to the center of each grain of the carbonaceous reductant. It can contribute to a reduction reaction. Moreover, the adhesiveness and dispersibility with an ore can also be maintained favorable.

Here, the “average reducing agent particle volume ratio” of the reducing agent particles is an average value of volume ratios (reducing agent particle volume ratios) of arbitrary 300 reducing agent particles, and is obtained by the following formula (1). . The “reducing agent particle volume ratio” is a ratio of the reducing agent particle volume when the volume of a sphere having the maximum particle length of the reducing agent particle as a diameter is defined as 100%. Desired.
Average reducing agent particle volume ratio = total of reducing agent particle volume ratio of 300 reducing agent particles / 300 (1)
Reducing agent particle volume ratio = (volume of reducing agent particle / volume of sphere having diameter of maximum particle length of reducing agent particle) × 100
... (2)

  In the above formula (2), the “maximum particle length” is the longest side or diameter of the reducing agent particles. FIG. 2 is a schematic diagram of the maximum particle length D of the reducing agent particle 1 and a sphere C having the maximum particle length D as a diameter. When the reducing agent particles are irregular, the maximum particle length is determined as shown in FIG. More specifically, for example, if the reducing agent particles are elliptical, the maximum particle length is a long diameter, and if the reducing agent particles are a rectangular parallelepiped shape, the maximum particle length is a diagonal line.

  This “maximum particle length” can be measured using a metallographic microscope. Moreover, since the density of the reducing agent particles is known, the volume of the reducing agent particles can be calculated by measuring the mass. Thus, the reducing agent particle volume ratio is obtained from the measured values of the volume and the maximum particle length of 300 randomly selected reducing agent particles, and the average reducing agent particle volume ratio is further calculated by the equation (1). .

  As described above, the average reducing agent particle volume ratio of the reducing agent particles contained in the carbonaceous reducing agent is 5% or more, preferably 15% or more. If the average volume ratio of the reducing agent particles is too small, the proportion of scale-like particles will increase, making it difficult to mix with nickel oxide ore, and reducing the contact area between the nickel oxide ore and the carbonaceous reducing agent. When the scaly carbonaceous reducing agents stick to each other or agglomerate, it becomes difficult to disperse in the mixture. As a result, the reduction reaction tends to be non-uniform.

  The average reducing agent particle volume ratio of the reducing agent particles is 80% or less, preferably 70% or less. If the average volume ratio of the reducing agent particles is too large, the reducing agent particles have a shape close to a sphere, and the contact area with the nickel oxide ore is reduced, so that the reduction reaction tends to be non-uniform.

The “average maximum particle length” is an average value of the maximum particle length D in the number average among 300 randomly selected reducing agent particles, and can be obtained by the following formula (3).
Average maximum particle length = the sum of the maximum particle lengths of 300 reducing agent particles / 300 (3)

  As described above, the average maximum particle length of the reducing agent particles contained in the carbonaceous reducing agent is 5 μm or more, preferably 10 μm or more. If the average maximum particle length is too small, the carbonaceous reducing agent aggregates and the carbonaceous reducing agent is not sufficiently dispersed in the mixture. Moreover, there is a concern that the fine powder will behave as dust during mixing, which may deviate from the set content.

  The average maximum particle length is 500 μm or less, preferably 150 μm or less. If the average maximum particle length value is too large, the proportion of coarse reducing agent particles increases too much, so the dispersibility of the carbonaceous reducing agent in the mixture deteriorates, making it difficult to obtain a uniform mixture, Segregation is likely to occur. As a result, the reduction reaction tends to be non-uniform.

  Thus, the carbonaceous reducing agent added to the raw material ore is composed of particles (reducing agent particles), and the reducing agent particles have an average reducing agent particle volume ratio of 5% to 80%, and an average By using a particle having a maximum particle length of 5 μm or more and 500 μm or less, the contact area between the carbonaceous reducing agent and the nickel oxide ore is increased, thereby improving the adhesion. Further, the dispersibility of the carbonaceous reducing agent in the mixture is increased, and the carbonaceous reducing agent and the nickel oxide ore are uniformly mixed. As a result, in the reduction treatment step S3, which will be described later, uniform reduction can be realized more efficiently, so that the reaction time can be shortened and the manufacturing cost can be reduced, and the resulting ferronickel can be obtained. Can improve the quality.

  The amount of the carbonaceous reducing agent in the mixture, that is, the amount of the carbonaceous reducing agent to be included in the mixture, is the chemical equivalent necessary for nickel metal reduction of the total amount of nickel oxide constituting the nickel oxide ore. When the total value of both the chemical equivalents necessary for reducing iron oxide (ferric oxide) to metallic iron (for convenience, also referred to as “total value of chemical equivalents”) is 100% by mass, Can be adjusted so as to have a carbon content ratio of 5 mass% or more and 60 mass% or less, more preferably a carbon content ratio of 10 mass% or more, or a carbon content ratio of 40 mass% or less. By setting the mixing amount of the carbonaceous reducing agent to a ratio of 5% by mass or more with respect to 100% by mass of the total value of chemical equivalents, the reduction of nickel can be efficiently progressed and productivity is improved. On the other hand, by setting the ratio of 60% by mass or less to 100% by mass of the total value of chemical equivalents, it is possible to suppress the reduction amount of iron, prevent the deterioration of nickel quality, and produce high-quality ferronickel. it can.

  Thus, preferably, the amount of the carbonaceous reducing agent is set to a ratio of 5% by mass or more and 60% by mass or less of the carbon component with respect to the total value of 100% by chemical equivalent, so that the metal component is added to the surface of the mixture. The shell (metal shell) produced by the above can be uniformly produced to improve productivity, and high quality ferronickel with high nickel quality can be obtained, which is preferable.

(Iron ore)
In addition to nickel oxide ore and carbonaceous reducing agent, iron ore can be added as an optional component to adjust the iron-nickel ratio in the mixture. Here, the iron ore is not particularly limited. For example, iron ore having an iron grade of about 50% or more, hematite obtained by wet smelting of nickel oxide ore, or the like can be used.

(Binder, flux component)
Examples of the binder include bentonite, polysaccharides, resins, water glass, and dehydrated cake. Examples of the flux component include calcium oxide, calcium hydroxide, calcium carbonate, silicon dioxide and the like.

  Table 1 below shows an example of the composition (% by weight) of some raw material powders to be mixed in the mixing process step S1. The composition of the raw material powder is not limited to this.

  In the mixing treatment step S1, a mixture is obtained by uniformly mixing the raw material powder containing the nickel oxide ore as described above. In this mixing, the raw material powder may be kneaded. Here, kneading | mixing of raw material powder may be performed simultaneously with mixing, and may be performed after mixing. As a result, shear force is applied to the mixture, and the agglomeration of the raw material powders including the carbon reducing agent is dissolved and mixed more uniformly, thereby increasing the contact area between the raw material powders and reducing the voids contained in the mixture. Thus, the adhesion of each particle is improved. Therefore, the reaction time of the reduction reaction can be shortened, and quality variation can be reduced. Therefore, highly productive processing can be performed, and high quality ferronickel can be manufactured.

  Moreover, after kneading | mixing raw material powder, you may extrude a mixture using an extruder. Thus, by extruding with an extruder, a much higher kneading effect is obtained, so that the contact area between the raw material powders increases and the voids contained in the mixture decrease. Therefore, high quality ferronickel can be manufactured more efficiently.

<2. Reduction input pretreatment process (pretreatment process)>
The reduction pre-treatment process S2 is a process in which the mixture containing the nickel oxide ore and the carbonaceous reducing agent obtained in the mixing process S1 is formed and dried as necessary. That is, in this pre-reduction charging treatment step S2, the mixture obtained by mixing the raw material powders can be easily put into a furnace used in the reduction treatment step S3 described later, and the reduction reaction can be efficiently performed. Mold.

(1) Molding of mixture When molding the obtained mixture, the mixture may be agglomerated (granulated) to form a massive shaped body (pellet, briquette, etc.), and the mixture is filled into a container or the like. A filling container may be used.

(Agglomeration of the mixture)
Among these, when the mixture is agglomerated, a predetermined amount of water necessary for agglomeration is added to the mixture containing nickel oxide ore and a carbonaceous reducing agent, for example, a lump production apparatus (rolling granulation) Or a compression molding machine, an extrusion molding machine or the like, or a pelletizer), and is formed into a massive molded body such as pellets or briquettes (hereinafter sometimes simply referred to as “pellets”).

  The shape for molding the mixture, that is, the shape of the pellet is not particularly limited, and may be a cube, a rectangular parallelepiped, a cylinder, or a sphere. Among these, it is particularly preferable to form a spherical pellet. By using spherical pellets, the reduction reaction can be facilitated relatively uniformly, and the mixture can be easily molded to reduce the cost of molding. Moreover, since the shape of the pellet is simplified, it is possible to reduce the molding defects.

  The size of the pellet obtained by the agglomeration (diameter in the case of a spherical pellet) is not particularly limited. For example, the drying process in the pretreatment process S2 and the drying process in the reduction process S3 (drying process S31), If the reduction treatment (reduction step S33) is performed through the preheat treatment (preheating step S32), the thickness can be about 10 mm to 30 mm. The reduction process step S3 and the like will be described later in detail.

(Filling the mixture into the container)
On the other hand, when the mixture is filled into a container or the like and molded, the mixture containing the nickel oxide ore and the carbonaceous reducing agent is filled into a predetermined container or the like while kneading with an extruder or the like, can do. The obtained mixture-filled container may be used as it is for the subsequent reduction treatment step S3. However, the mixture contained in the container or the like is pressed and hardened for use in the reduction treatment step S3. preferable. In particular, the mixture contained in a container or the like is pressed and molded, and the formed mixture is subjected to the subsequent reduction treatment step S3, thereby reducing voids generated between the mixtures and increasing the density. In addition, since the density becomes uniform, the reduction reaction can be facilitated more uniformly. Therefore, ferronickel with less variation in quality can be produced.

  Although it does not specifically limit as a shape of a mixture filling container, For example, it is preferable that it is shapes, such as a rectangular parallelepiped, a cube, a cylinder. Moreover, although the size is not particularly limited, for example, in the case of a rectangular parallelepiped or a cube, it is generally preferable that the inner dimensions of the vertical, horizontal, and height are each 500 mm or less. By adopting such a shape and size, smelting with small variations in quality and high productivity can be performed.

(2) Drying treatment of the mixture The mixture containing the nickel oxide ore and the carbonaceous reducing agent may be subjected to a drying treatment at least before or after forming the mixture. Here, a mixture containing nickel oxide ore and a carbonaceous reducing agent may contain a lot of moisture, and when such a mixture is rapidly heated to the reduction temperature, the moisture is vaporized and expanded. May destroy the mixture. Moreover, the mixture is often in a state of being sticky due to moisture.

  Therefore, by subjecting the mixture to a drying treatment, for example, the solid content of the lump is about 70% by weight and the water content is about 30% by weight, so that the mixture collapses in the subsequent reduction treatment step S3. Can be prevented, thereby making it difficult to remove from the reduction furnace. Moreover, since the sticky state of the surface can be eliminated by subjecting the mixture to a drying treatment, handling up to charging into the reduction furnace can be facilitated.

  Specifically, the drying treatment for the mixture is not particularly limited, but for example, hot air of 200 ° C. to 400 ° C. is blown against the mixture to dry. In addition, it is preferable to maintain the temperature of the mixture at the time of a drying process below 100 degreeC from a viewpoint of making a pellet hard to be destroyed.

  The drying process may be performed only once or may be performed a plurality of times including the drying process (drying process S31) in the reduction process S3 described later. In addition, when performing a drying process only once, energy efficiency can be improved more by performing drying process S31 in reduction process process S3 so that it may mention later.

  Table 2 below shows an example of the composition (parts by weight) in the solid content of the pellets after the drying treatment. The composition of the pellet is not limited to this.

<3. Reduction process>
In the reduction treatment step S3, the mixture formed through the reduction addition pretreatment step S2 is charged into a reduction furnace and reduced to a predetermined reduction temperature. Thus, by heat-processing with respect to a mixture, a smelting reaction (reduction reaction) advances and the mixture of a metal and slag produces | generates.

  FIG. 3 is a process diagram showing the process executed in the reduction process S3. As shown in FIG. 3, the reduction treatment step S3 includes a drying step S31 for drying the mixture, a preheating step S32 for preheating the dried mixture, a reduction step S33 for heating and reducing the mixture, and the obtained reduction. And cooling step S35 for cooling the object. Moreover, you may have the temperature holding process S34 which hold | maintains the reduced material obtained through reduction process S33 in a predetermined temperature range.

  Here, the reduction heat treatment in the reduction treatment step S3 is performed using a reduction furnace or the like. The reduction furnace used for the reduction heat treatment is not particularly limited, but a moving hearth furnace is preferably used. By using a moving hearth furnace as the reducing furnace, after placing the mixture on the hearth outside the furnace, it can be charged into the moving hearth furnace, making the reducing furnace more efficient. It can be operated. Also, by using a moving hearth furnace, the reduction reaction proceeds continuously, and the reaction can be completed with one facility, and the processing temperature can be controlled rather than using a separate furnace for each process. Can be performed accurately. Furthermore, since each process is performed with one facility using a moving hearth furnace, heat loss is reduced and the atmosphere in the furnace can be controlled accurately, so that the reaction can proceed more effectively. Therefore, ferronickel with high nickel quality can be obtained more effectively.

  The moving hearth furnace is not particularly limited, and a rotary hearth furnace, a roller hearth kiln, or the like can be used. Among these, as an example using a rotary hearth furnace, for example, as shown in FIG. 4, the rotary hearth furnace (rotary hearth furnace) 20 is circular and is divided into a plurality of processing chambers 23 to 26. A reduction furnace 2 can be mentioned. The rotary hearth furnace 20 includes a hearth that rotates and moves on a plane, and the furnace floor on which the mixture is placed rotates and moves in a predetermined direction, whereby each process is performed in each region. At this time, the processing temperature in each region can be adjusted by controlling the time (movement time, rotation time) at the time of passing through each region. Smelted.

  In the rotary hearth furnace 20, for example, all the processing chambers 23 to 26 may be used as the reduction chambers, and the reduction treatment may be performed in the processing chambers 23 to 26 on the mixture 10 sequentially supplied from the drying chamber 21. On the other hand, the processing chamber 23 is a preheating chamber, the processing chamber 24 is a reduction chamber, the processing chamber 25 is a temperature holding chamber, and the processing chamber 26 is a cooling chamber. Then, preheating is performed, reduction processing is performed in the processing chamber 24, temperature is maintained in the processing chamber 25, cooling is performed in the processing chamber 26, and further cooling processing is performed in the external cooling chamber 27. As described above, when the temperatures are varied among the processing chambers 23 to 26, the processing chambers 23 to 26 are partitioned by a movable partition wall in order to strictly control the reaction temperature and suppress energy loss. A configuration is preferable. In addition, the arrow on the rotary hearth furnace 20 in FIG. 4 shows the moving direction of a processed material (mixture) while showing the rotation direction of a hearth.

  By performing these treatments in a single reduction furnace using the rotary hearth furnace 20, the temperature in the reduction furnace can be maintained at a high temperature. There is no need to raise or lower the energy cost, and the energy cost can be reduced. Therefore, ferronickel with high productivity and good quality can be produced continuously and stably.

  In particular, when the mixture is charged into the reduction furnace, a carbonaceous reducing agent (hereinafter also referred to as “furnace carbonaceous reducing agent”) is preliminarily spread on the hearth of the reducing furnace, and the hearth carbon that has been spread. The mixture may be placed on the quality reducing agent. Further, after the container filled with the mixture is placed on the hearth carbonaceous reducing agent, it can be covered with the carbonaceous reducing agent. As described above, the reduction heat treatment is performed in a state where the mixture is charged into the reduction furnace in which the carbonaceous reducing agent is spread on the hearth or is surrounded by the carbonaceous reducing agent so as to further cover the charged mixture. By applying, the smelting reaction can proceed more rapidly while suppressing the collapse of the mixture. Moreover, even if the reduction reaction proceeds in the processing chambers 23 to 26 and nickel metal or slag is generated by laying down the hearth carbonaceous reducing agent in particular, the reaction with the hearth can be suppressed. Soaking and sticking can be reduced.

(1) Drying process In drying process S31, a drying process is performed with respect to the mixture obtained by mixing raw material powder. The main purpose of this drying step S31 is to blow off water and crystal water in the mixture.

  The mixture obtained in the mixing treatment step S1 contains a large amount of moisture and the like, and when it is rapidly heated to a high temperature such as the reduction temperature during the reduction treatment, the moisture is vaporized and expanded all at once. The resulting mixture is cracked and, in some cases, ruptured into pieces, making it difficult to perform uniform reduction treatment. Therefore, by performing a drying process on the mixture to remove moisture before performing the reduction process, it is possible to reduce such destruction of the mixture and thereby promote a uniform reduction process.

  It is preferable that the drying process in drying process S31 is performed in the form connected to a reduction furnace. On the other hand, it is conceivable to provide an area (drying area) for performing a drying process in the reduction furnace, but in this case, since the drying process in the drying area becomes rate limiting, the efficiency of the process in the reduction step S33 is There is a possibility that the efficiency of the process in the temperature holding step S34 is lowered.

  Therefore, it is preferable that the drying process in drying process S31 is performed in the drying chamber provided outside the furnace which performs a reduction reaction, and connected directly or indirectly to the furnace. For example, in the reduction furnace 2 of FIG. 4, by providing a drying chamber 21 outside the rotary hearth furnace 20, a drying chamber can be designed completely separate from the steps such as preheating, reduction, and cooling described later, The pre-heat treatment, the reduction treatment, and the cooling treatment can be easily performed. For example, when a lot of moisture remains in the mixture depending on the raw material, the drying process takes time. Therefore, the drying chamber 21 is designed to have a longer overall length, or inside the drying chamber 21. What is necessary is just to design so that the conveyance speed of this mixture 10 may become slow.

  Although the method of the drying process in drying process S31 is not specifically limited, It can carry out by spraying a hot air with respect to the mixture 10 conveyed in the drying chamber 21. FIG. Further, the drying temperature of the drying chamber 21 is not particularly limited, but is preferably set to 500 ° C. or lower from the viewpoint of preventing the reduction reaction from starting, and the entire mixture 10 is uniformly dried at a temperature of 500 ° C. or lower. More preferably.

(2) Preheating process In preheating process S32, the mixture after water | moisture content was removed by the drying process in drying process S31 is preheated (preheating). The main purpose of the preheating step S32 is to allow the temperature to rise smoothly to the reduction temperature during reduction.

  When the mixture is charged from the outside to the inside of the furnace where the reduction reaction is performed, the mixture may be rapidly heated to the reduction temperature, and the mixture may be broken or become powdery due to thermal stress. In addition, since the temperature of the mixture does not rise uniformly, the reduction reaction may vary, and the quality of the metal produced may vary. Therefore, after performing drying process S31 with respect to a mixture, it is preferable to preheat even to predetermined temperature, and thereby, destruction of a mixture and the dispersion | variation in a reductive reaction can be suppressed.

  The preheating process in the preheating step S32 may be performed in a preheating chamber provided in the rotary hearth furnace, provided outside the rotary hearth furnace, and continuously from the drying chamber to the rotary hearth furnace through the preheating chamber. You may carry out in the preheating chamber provided. For example, in the reduction furnace 2 shown in FIG. 4, the inside of the rotary hearth furnace 20 is formed by setting a processing chamber 23 provided continuously from the drying chamber 21 in the rotary hearth furnace 20 as a preheating chamber. Therefore, the energy required for reheating the rotary hearth furnace 20 supplied with the mixture 10 in the reduction step S33 can be greatly reduced.

  Although it does not specifically limit as preheating temperature in preheating process S32, It is preferable that it is 600 degreeC or more, and it is more preferable that it is 700 degreeC or more. On the other hand, the upper limit of the preheating temperature in the preheating step S32 may be 1280 ° C. In particular, by performing the treatment at a high preheating temperature, it is possible to significantly reduce the energy required for reheating to the reduction temperature in the reduction step S33.

(3) Reduction step In the reduction step S33, the mixture preheated in the preheating step S32 is subjected to reduction treatment at a predetermined reduction temperature. The main purpose of the reduction step S33 is to reduce the mixture preheated in the preheating step S32.

  In the reduction treatment using a reduction furnace, nickel oxide, which is a metal oxide contained in nickel oxide ore, is reduced as completely as possible, while it is derived from iron ore mixed as raw material powder together with nickel oxide ore. It is preferable that iron oxide is partially reduced so that the desired nickel-grade ferronickel is obtained.

  Although it does not specifically limit as reduction temperature in reduction process S33, It is preferable to set it as the range of 1200 to 1450 degreeC. Here, the reduction temperature in the reduction step S33 is preferably 1200 ° C, more preferably 1300 ° C. The reduction temperature in the reduction step S33 is preferably 1450 ° C., more preferably 1400 ° C. By reducing in such a temperature range, the reduction reaction easily proceeds uniformly, so that a metal (ferronickel) with suppressed variation in quality can be generated. Moreover, a desired reduction reaction can be advanced in a relatively short time by reducing in this temperature range.

  The time for performing the reduction heat treatment in the reduction step S33 is set according to the temperature of the reduction furnace, but is preferably 10 minutes or more, and more preferably 15 minutes or more. On the other hand, the upper limit of the time during which the reduction heat treatment is performed in the reduction step S33 may be 50 minutes or less or 40 minutes or less from the viewpoint of suppressing an increase in manufacturing cost.

  In the reduction heat treatment in the reduction step S33, nickel oxide and iron oxide are first reduced and metallized in the vicinity of the surface of the mixture where the reduction reaction easily proceeds in a short time of about 1 minute, for example, and an iron-nickel alloy (ferronickel) ) To form a shell (hereinafter also referred to as “shell”). On the other hand, in the shell, with the formation of the shell, the slag component in the mixture gradually melts to form liquid phase slag. As a result, in one mixture, a metal made of an alloy such as ferronickel or a metal (hereinafter simply referred to as “metal”) and a slag made of an oxide (hereinafter simply referred to as “slag”) are separated. Generate.

  And when the processing time of the reduction heat treatment in the reduction step S33 has passed about 10 minutes, the excess carbon component of the carbonaceous reducing agent not involved in the reduction reaction is taken into the iron-nickel alloy to lower the melting point. As a result, the iron-nickel alloy containing carbon melts and becomes a liquid phase.

  As described above, the slag formed by the reduction heat treatment is melted into a liquid phase, but the metal and slag that have already been separated and produced do not mix with each other. As a separate phase with slag solid phase, it becomes a mixed material. The volume of the mixture is contracted to a volume of about 50% to 60% as compared with the mixture to be charged.

  The reduction process in the reduction step S33 is performed using a reduction furnace or the like as described above. For example, when performing reduction process S33 in the processing chamber 24 of the reduction furnace 2 of FIG. 4, after preheating a mixture in the processing chamber 23 which is a preheating chamber, it is preferable to move to the processing chamber 24 by rotation of a hearth.

(4) Temperature holding process You may perform the temperature holding process S34 hold | maintained on predetermined temperature conditions within a rotary hearth furnace with respect to the reduced material obtained through reduction process S33. Specifically, in this temperature holding step S34, the reduction product in the reduction step S33 is held at an equivalent temperature, so that the metal components in the reduction product are further settled and gathered to coarsen the metal. Thereby, metal can be easily collected.

  When the metal component in the reduced product is small in the state obtained by the reduction treatment, for example, when a bulk metal of about 200 μm or less is obtained, the metal and slag are separated in the subsequent separation step S4. Becomes difficult. At this time, if necessary, the reduced product is kept at a high temperature, so that the metal having a specific gravity larger than that of the slag in the reduced product can be settled and aggregated to coarsen the metal.

  The holding temperature of the reduced product in the temperature holding step S34 can be appropriately set according to the reduction temperature in the reducing step S33, and is preferably in the range of 1300 ° C. or higher and 1500 ° C. or lower. By maintaining the reduced product at a high temperature within this temperature range, the metal component in the reduced product can be efficiently precipitated to obtain a coarse metal. Here, when the holding temperature is less than 1300 ° C., a large part of the reduced product becomes a solid phase, so that it takes time to obtain a coarse metal even if the metal component does not settle or settles. . In addition, if the holding temperature exceeds 1500 ° C., the reduction product may not be recovered due to the reaction between the obtained reduction product and the hearth or hearth carbonaceous reducing agent, and the furnace may be damaged. I might let you.

  The time for holding the temperature in the temperature holding step S34 is set according to the temperature of the reduction furnace, but is preferably 10 minutes or more, and more preferably 15 minutes or more. On the other hand, the upper limit of the time for holding the temperature in the temperature holding step S34 may be 50 minutes or less or 40 minutes or less from the viewpoint of suppressing an increase in manufacturing cost.

  The treatment in the temperature holding step S34 is preferably performed continuously following the reduction step S33 in a furnace that performs a reduction reaction. For example, when the temperature holding step S34 is performed in the processing chamber 25 of the reduction furnace 2 in FIG. 4, it is preferable to reduce the mixture in the processing chamber 24 and then move the mixture to the processing chamber 25 by rotating the hearth.

  As described above, by continuously performing the reduction step S33 and the temperature holding step S34, the metal component in the reduction product is efficiently settled, so that the obtained metal can be coarsened. Moreover, since heat loss between each process reduces by this, efficient operation can be performed.

  In addition, when the metal is coarsened to the level which does not have a manufacturing problem by the reduction process in the reduction process S33, it is not particularly necessary to provide the temperature holding process S34.

(5) Cooling step The cooling step S35 is cooled down to a temperature at which the reduced product after maintaining the temperature in the temperature maintaining step S34 can be separated and recovered in the subsequent separation step S4 after passing through the reduction step S33. It is a process to do.

  Cooling of the reduced product in the cooling step S35 can be performed in at least one of a processing chamber inside the furnace in which the reduction reaction is performed and a processing chamber connected to the outside of the furnace. For example, in the reduction furnace 2 of FIG. 4, the temperature drop inside the rotary hearth furnace 20 is reduced by using the processing chamber 26 of the rotary hearth furnace 20 as a cooling chamber and providing the external cooling chamber 27 outside the furnace. Therefore, the energy loss in the reduction furnace 2 can be reduced. In particular, since it becomes difficult for heat to be transferred from the rotary hearth furnace 20 to the external cooling chamber 27, the reduced product can be cooled more smoothly.

  In the cooling step S35, the temperature at which the reduced product that has passed through the reducing step S33 is transferred to the cooling chamber (hereinafter also referred to as “recovery temperature”) may be any temperature that allows the reduced product to be handled substantially as a solid. In particular, when the reduction step S33 is performed using a rotary hearth furnace, the recovery temperature is preferably as high as possible. At this time, by raising the temperature at the time of recovery as much as possible, the temperature drop of the hearth of the rotary hearth furnace 20 until it is transferred to the cooling chamber is reduced. Therefore, energy loss due to cooling to the rotary hearth and the atmosphere in the furnace and preheating can be reduced, and energy required for reheating can be further saved.

  Here, the recovery temperature in the cooling step S35 is preferably 600 ° C. or higher. By setting the temperature at the time of recovery to such a high temperature, the energy required for reheating is significantly reduced, so that an efficient smelting process can be performed at a lower cost. Further, since the temperature difference in the hearth of the rotary hearth furnace 20 is reduced, the thermal stress applied to the hearth and the furnace wall is also reduced, so that the life of the rotary hearth furnace 20 can be greatly extended. Problems during operation of the rotary hearth furnace 20 can be greatly reduced.

  In the present embodiment, when the reaction in the reduction treatment step S3 progresses ideally, the mixture after the reduction treatment step S3 is a mixture of metal and slag. At this time, by forming a large lump of metal, it is possible to reduce the time and effort required for recovery from the reduction furnace, and it is possible to suppress a decrease in the metal recovery rate.

<4. Separation process>
In the separation step S4, metal (ferronickel metal) is separated and recovered from the reduced product generated in the reduction treatment step S3. Specifically, the metal phase is separated and recovered from a mixture (reduced product) containing a metal phase (metal solid phase) and a slag phase (slag solid phase) obtained by reducing and heating the mixture. To do.

  As a method for separating the metal phase and the slag phase from the mixture of the metal phase and the slag phase obtained as a solid, for example, in addition to removing unnecessary materials by sieving, separation by specific gravity, separation by magnetic force, etc. Can be used. In addition, the obtained metal phase and slag phase can be easily separated because of poor wettability. For example, the above-mentioned large mixture can be dropped with a predetermined drop or screened. At this time, by applying an impact such as applying a predetermined vibration, the metal phase and the slag phase can be easily separated from the mixture.

  In this way, by separating the metal phase and the slag phase, the metal phase can be recovered and made into a ferronickel product.

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

[Mixing process]
About each sample of Examples 1-12 and Comparative Examples 1-3, nickel oxide ore as raw material ore, iron ore, silica sand and limestone as flux components, binder, and carbonaceous reducing agent (coal powder) Mixing was performed using a mixer while adding an appropriate amount of water.

Here, the carbonaceous reducing agent is composed of particles (reducing agent particles), and the value of the average reducing agent particle volume fraction and the value of the average maximum particle length are those shown in Table 4. Was used. In addition, the content of the carbonaceous reducing agent is 100 mass of the amount necessary for reducing nickel oxide (NiO) and iron oxide (Fe ₂ O ₃ ) contained in the nickel oxide ore that is the raw material ore without excess or deficiency. %, It was set to 34% by mass.

  In addition, the average maximum particle length described in Table 4 was obtained from the average value of the maximum particle lengths of 300 reducing agent particles randomly selected and measured using a metal microscope. Further, the volume of the reducing agent particles was determined by measuring the mass because the density of the reducing agent particles is known.

  And after mixing a raw material using a mixer, the mixture was obtained by kneading | mixing a raw material using a biaxial kneader.

[Pretreatment process]
The mixture obtained by the mixing process is agglomerated by forming into a spherical pellet of φ18 ± 1.5 mm using a pan-type granulator, and then the solid content is about 70% by weight and the water content is 30%. A drying treatment was performed by blowing hot air of 200 ° C. to 250 ° C. so that it would be about%. Table 3 below shows the solid content composition (excluding carbon) of the mixture (pellet) after the drying treatment.

[Reduction treatment process]
The pellets after the pretreatment were respectively charged into a reduction furnace having a rotary hearth furnace in a nitrogen atmosphere substantially free of oxygen. As the reduction furnace, as shown in FIG. 4, a reduction furnace having a rotary hearth furnace 20 provided with four processing chambers 23 to 26 so as to divide the region in which the hearth rotationally moves into four parts was used. In the reduction furnace 2, the drying chamber 21 is connected to the processing chamber 23 of the rotary hearth furnace 20, and the external cooling chamber 27 is connected to the processing chamber 26 of the rotary hearth furnace 20.

  And after charging the drying chamber 21 connected to the outside of the rotary hearth furnace 20 and performing the drying treatment, the drying chamber 21 was continuously provided in the rotary hearth furnace 20. The pellets were transferred to the processing chamber 23, which is a preheating chamber, and the temperature in the preheating chamber was maintained in the range of 700 ° C. or higher and 1280 ° C. or lower, and the pellet was pre-heat-treated.

  Subsequently, the preheat-treated pellets were transferred to the treatment chamber 24 in the rotary hearth furnace 20 and subjected to reduction treatment at the temperatures and times shown in Table 4.

  The reduced product of the pellets obtained through the reduction treatment is transferred in the order of the treatment chamber 25 which is a temperature holding chamber maintained at the same temperature as the reduction temperature shown in Table 4, and the treatment chamber 26 which is a cooling chamber, and then Then, it was transferred to the external cooling chamber 27 connected to the rotary hearth furnace 20, and quickly cooled to room temperature while flowing nitrogen and taken out into the atmosphere. The reductant was collected from the rotary hearth furnace 20 when the reductant was transferred to the external cooling chamber 27, and was collected by placing the reductant along a guide installed in the external cooling chamber 27.

  Moreover, about each sample after reduction heat processing, the nickel metalization rate and the nickel content rate in a metal were analyzed and calculated by the ICP emission-spectral-analyzer (SHIMAZU S-8100 type | mold).

The nickel metal conversion rate and the nickel content rate in the metal were calculated by the following equations.
Nickel metal conversion rate =
Amount of Ni metalized in pellets / (total amount of Ni in pellets) × 100 (%)
Nickel content in metal =
Amount of metallized Ni in pellet ÷ (total amount of metallized Ni and Fe in pellet) x 100 (%)

  Table 4 below shows the nickel metal conversion rate of metals obtained from the samples of Examples 1 to 12 and Comparative Examples 1 to 4, and the nickel content in the metal.

  As shown in the results of Table 4, the carbonaceous reducing agent is constituted by particles (reducing agent particles), the average reducing agent particle volume ratio of the reducing agent particles is 5% or more and 80% or less, and the reducing agent. By using particles having an average maximum particle length of 5 μm or more and 500 μm or less, the nickel metal conversion rate is as high as 98.4% or more, and the nickel content in the metal is also high as 18.2% or more. It was found that ferronickel can be produced (Examples 1 to 12).

  As described above, the reason why the high-quality ferronickel could be produced is that the nickel oxide ore and the carbonaceous reducing agent are brought into contact with each other by containing a carbonaceous reducing agent having a specific size and a predetermined shape. It is conceivable that the uniformity of the area and the mixture has been increased, thereby enabling uniform and efficient smelting treatment.

  On the other hand, as shown in the results of Comparative Example 1, when the average reducing agent particle volume ratio is more than 80%, the nickel metallization ratio is 91.2%, and the nickel content in the metal is 15.2. It was 1% and was a low value compared with the Example.

  Further, as shown in the results of Comparative Examples 2 to 3, when the average maximum particle length of the reducing agent particles is less than 5 μm (Comparative Example 2), or exceeds 500 μm (Comparative Example 3), nickel metallization is performed. The rate was 86.8% at the highest, and the nickel content in the metal was 14.3% at the highest, which was a low value compared to the examples.

DESCRIPTION OF SYMBOLS 1 Reducing agent particle 10 Mixture 2 Reduction furnace 20 Rotary hearth furnace 21 Drying chamber 23-26 Processing chamber 27 External cooling chamber

Claims (4)

A smelting method in which an oxidized ore and a carbonaceous reducing agent are mixed, and the resulting mixture is heated and subjected to a reduction treatment to obtain a reduced metal and slag.
Using the carbonaceous reducing agent composed of particles (reducing agent particles),
About the reducing agent particles, the average reducing agent particle volume ratio obtained by the following formulas (1) and (2) is 5% or more and 80% or less,
A method for smelting an oxidized ore having an average maximum particle length of 5 μm or more and 500 μm or less determined by the following formula (3)
Average reducing agent particle volume ratio = total of reducing agent particle volume ratio of 300 reducing agent particles / 300 (1)
Reducing agent particle volume ratio = (volume of reducing agent particle / volume of sphere having diameter of maximum particle length of reducing agent particle) × 100
... (2)
Average maximum particle length = the sum of the maximum particle lengths of 300 reducing agent particles / 300 (3) The method for smelting an oxidized ore according to claim 1, wherein a reduction temperature in the reduction treatment is 1200 ° C or higher and 1450 ° C or lower. The method for smelting an oxide ore according to claim 1, wherein the oxide ore is a nickel oxide ore. The method for refining oxide ore according to any one of claims 1 to 3, wherein the metal is ferronickel.

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