JP2019035127A - Method for smelting oxide ore and reduction furnace - Google Patents

Abstract

To provide a smelting method that produces metal by reducing a mixture containing oxide ore such as nickel oxide ore, where the method makes it possible to efficiently recover metal, the produced metal having high quality with less variation in quality.SOLUTION: The present invention provides an oxide ore smelting method in which, a mixture obtained by mixing oxide ore and a carbonaceous reductant is put on a furnace bed of a reduction furnace, and the mixture is subjected to a reduction treatment in the reduction furnace. A reduction product from the reduction treatment of the mixture is extruded and recovered along the furnace bed 13 of the reduction furnace 1, with a recovery tool 15 provided in the reduction furnace 1.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a method for smelting oxide ore, for example, a smelting method for obtaining a reduced product by reducing nickel oxide ore or the like with a carbonaceous reducing agent as a raw material, and a reduction furnace used for the reduction treatment About.

  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, when producing pellets, it is important to uniformly mix the mixture, or 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.

  For example, Patent Document 1 discloses a technique relating to a method for producing ferronickel, and as a pretreatment when producing ferronickel using a moving hearth furnace, a raw material containing nickel oxide and iron oxide, In the mixing step of mixing with a carbonaceous reducing agent to make a mixture, a technique is disclosed in which pellets are manufactured while adjusting the amount of excess carbon in the mixture, and the pellets are charged into a furnace to perform a reduction step. Yes.

  Here, in Patent Document 1, a mixer is used to mix the raw material and the carbonaceous reducing material, and the obtained mixture may be charged into the moving hearth furnace as it is. It is preferable to agglomerate, and this agglomeration reduces the amount of dust generated from the mobile hearth furnace and melting furnace, and the heat transfer efficiency inside the agglomerate (mixture) in the mobile hearth furnace Is improved and the reduction rate is increased. Further, it is described that the granulated agglomerate (mixture) is charged into a moving hearth furnace and heated and reduced at an ambient temperature of 1000 to 1400 ° C.

  However, although Patent Document 1 has a description that the mixture may be charged into a moving hearth furnace as it is, the melting point of nickel oxide ore slag is generally about 1300 ° C to 1400 ° C, and Since the hearth made of metal is used in the moving hearth furnace, the hearth reacts with the molten slag, and it is considered impossible to smelt nickel oxide ore. That is, in the reduction of the mixture, it is required that the hearth and slag do not react.

  Further, when the reduced mixture is recovered as it is to separate the slag and the metal, if the metal is too small, it is difficult to separate the slag and the metal. Therefore, for example, it is necessary to hold the reduced mixture in a semi-molten state or a molten state to effectively coarsen the metal.

  In such a case, it is necessary to uniformly generate a reduction reaction for the mixture in the reduction furnace. In order to produce a coarse metal and to uniformly separate the slag and the metal, it is important to make the reaction temperature and the furnace atmosphere uniform. However, when taking out the obtained reactant (reduced product) from the reduction furnace after reduction, if it takes time to take out the product, uneven metal generation occurs, resulting in uneven composition and size. It may become a metal.

  When a reduction furnace having a moving hearth such as a rotary furnace is used in order to improve productivity, there is a problem that the time required for equipment clearance and removal is increased, causing a uniform reaction. It is not easy to obtain a metal having a uniform composition and size.

  In this way, in the production of metal by mixing oxide ores such as nickel oxide ore and reducing the mixture, metal that has been effectively coarsened by reduction is efficiently recovered, and high-quality metal is consistent. There were many problems in manufacturing.

JP 2004-156140 A

  The present invention has been proposed in view of such circumstances, and efficiently recovers metal in a smelting method for producing metal by reducing a mixture containing oxidized ore such as nickel oxide ore. It is another object of the present invention to provide a method capable of producing a high-quality metal with little variation in quality.

  As a result of intensive studies, the present inventor performs a reduction process using a reduction furnace equipped with a specific recovery tool, and recovers the reduction product on the hearth obtained by the reduction process by pushing out the recovery tool. Thus, the inventors have found that the above-described problems can be solved, and have completed the present invention.

  (1) In the first invention of the present invention, a mixture obtained by mixing an oxide ore and a carbonaceous reducing agent is placed on the hearth of a reduction furnace, and the oxidation ore subjected to reduction treatment in the reduction furnace A method for smelting oxide ore, wherein a reduction product produced by a reduction treatment on the mixture is recovered by being pushed out along a hearth of the reduction furnace by a recovery tool provided in the reduction furnace. It is.

  (2) According to a second aspect of the present invention, in the first aspect, the recovery tool includes a shaft that slides in a direction toward the discharge port of the reduction furnace in parallel with the surface of the hearth of the reduction furnace. An extruding plate that is provided at the tip of the shaft and that extrudes the reduced product on the hearth of the reduction furnace, and is disposed on the hearth by the extruding plate that moves by sliding the shaft of the recovery tool. This is a method for smelting ore oxide, in which the reduced product is pushed out of the furnace through the outlet and recovered.

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

  (4) The fourth invention of the present invention is the method of smelting ore oxide according to claim 3, wherein the reduced product is recovered at a temperature of 1350 ° C. or lower in the third invention.

  (5) A fifth invention of the present invention is the method of smelting an oxide ore according to any one of the first to fourth inventions, wherein the oxide ore is a nickel oxide ore.

  (6) A sixth invention of the present invention is the method of smelting the oxidized ore according to any one of the first to fifth inventions, wherein the reduced product contains ferronickel.

  (7) A seventh invention of the present invention is a reduction furnace for subjecting a mixture obtained by mixing an oxide ore and a carbonaceous reducing agent to a reduction treatment, wherein the mixture is placed. A floor, a recovery tool for recovering the reduced product generated on the hearth by the reduction treatment, and an outlet for discharging the reduced product to the outside of the furnace, the recovery tool being parallel to the surface of the hearth And a shaft that slides in a direction toward the discharge port, and an extrusion plate that is provided at the tip of the shaft and that extrudes a reduction product on the hearth of the reduction furnace.

  According to the present invention, in a smelting method for producing metal by reducing a mixture containing oxide ore such as nickel oxide ore, the metal can be efficiently recovered, and there is little quality variation and high quality. Metal can be manufactured.

It is process drawing which shows an example of the flow of the smelting method of nickel oxide ore. It is sectional drawing which shows an example of a structure of a reduction furnace.

  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 an oxide ore, and the nickel oxide ore is mixed with a carbonaceous reducing agent to reduce nickel contained in the mixture preferentially 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, in the method for smelting oxidized ore according to the present invention, a mixture obtained by mixing oxide ore and a carbonaceous reducing agent is placed on the hearth of a reduction furnace, and reduction treatment is performed in the reduction furnace. The smelting method of oxidized ore to be applied is characterized in that the reduction product on the hearth generated by the reduction treatment on the mixture is extruded and recovered by a recovery tool provided in the reduction furnace.

  As the recovery tool provided in the reduction furnace, for example, an apparatus provided with a shaft that slides in a direction toward the discharge port of the reduction furnace and an extrusion plate that extrudes the reduction product on the hearth of the reduction furnace can be used. . In this smelting method, the reduced material on the hearth is pushed out of the furnace through the discharge port and collected by an extrusion plate that moves by sliding the shaft of the collecting tool.

  According to such a smelting method, the reduced product obtained by the reduction treatment is recovered by pushing it out of the furnace using a recovery tool, so that all the reduced product can be recovered at once, that is, The time taken out from the reduction furnace can be shortened. Thereby, the dispersion | variation in quality becomes small and a high quality metal can be collect | recovered stably. Moreover, according to such a method, the metal coarsened effectively can be collect | recovered, and according to such a metal, it becomes easy to sort with slag, and a metal can be collect | recovered efficiently.

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. Thus, an iron-nickel alloy (ferronickel) can be produced 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 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 for mixing raw materials containing nickel oxide ore, a mixture forming step S2 for forming the obtained mixture into a predetermined shape, and a formed mixture ( A reduction treatment step S3 for reducing and heating the pellet) at a predetermined reduction temperature, and a separation step S4 for separating the metal and slag generated in the reduction treatment step S3 and recovering the metal.

<2-1. 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 as an optional additive, for example, iron ore, a flux component, a binder, 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.

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 ).

  Although it does not specifically limit as a carbonaceous reducing agent, For example, coal powder, coke powder, etc. are mentioned. In addition, it is preferable that the carbonaceous reducing agent has a particle size or particle size distribution equivalent to that of the nickel oxide ore that is the raw material ore because it is easy to mix uniformly and the reduction reaction easily proceeds uniformly.

  The amount of carbonaceous reductant mixed is the chemical equivalent required to reduce the total amount of nickel oxide composing nickel oxide ore to nickel metal and necessary to reduce iron oxide (ferric oxide) to metallic iron. When the total value of both chemical equivalents (also referred to as “total value of chemical equivalents” for convenience) is 100% by mass, the proportion of carbon content is preferably 5% by mass to 60% by mass, more preferably It can adjust so that it may become a ratio of the carbon amount of 10 mass% or more and 40 mass% or less. Thus, by making the mixing amount of the carbonaceous reducing agent 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 advanced and the productivity is improved. improves. 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.

  Moreover, as an iron ore which is an additive of optional components, for example, iron ore having an iron grade of about 50% or more, hematite obtained by wet refining of nickel oxide ore, or the like can be used.

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

  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, kneading may be performed at the same time in order to improve the mixing property, or kneading may be performed after mixing. Specifically, the kneading can be performed using, for example, a 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. is released, and uniform. In addition, the adhesion of each particle can be improved, and the voids can be reduced. As a result, the reduction reaction can easily occur and the reaction can be performed uniformly, and the reaction time of the reduction reaction can be shortened. In addition, quality variations can be suppressed. As a result, highly productive processing can be performed, and high quality ferronickel can be produced.

  Further, after kneading, it may be extruded using an extruder. Thus, by extruding with an extruder, an even higher kneading effect can be obtained.

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

<2-2. Mixture molding process>
The mixture forming step S2 is a step of forming the mixture obtained in the mixing process step S1. Specifically, the mixture obtained by mixing the raw material powders is formed into a lump (agglomerated product, hereinafter also referred to as “pellet”) having a certain size or larger. Therefore, the mixture forming step S2 can also be referred to as a pellet manufacturing step.

  The molding method is not particularly limited, but an amount of water necessary to agglomerate the mixture is added. For example, a mass production apparatus (such as a rolling granulator, a compression molding machine, an extrusion molding machine, or a pelletizer) is used. To form pellets of a predetermined shape.

  As a shape of the pellet obtained by shape | molding a mixture, it can be set as a spherical shape, a rectangular parallelepiped shape, a cube shape, a column shape etc., for example. By setting it as such a shape, it becomes easy to shape | mold a mixture and the cost concerning shaping | molding can be suppressed. Moreover, since the shape mentioned above is a simple shape and is not complicated, generation | occurrence | production of inferior goods can be suppressed and the quality of the obtained pellet can also be made uniform.

  Further, as the shape of the pellets, it is preferable that the pellets can be processed in a stacked state in the subsequent reduction treatment process. Also in this respect, the pellets are spherical, rectangular parallelepiped, cubic, cylindrical, etc. If it exists, it can be easily stacked and placed in the reduction furnace, and the amount of treatment used for the reduction treatment can be increased. In addition, by stacking and subjecting to reduction treatment in this way, the amount of treatment during reduction can be increased without enlarging one pellet, making it easy to handle and falling apart when moving. The occurrence of defects and the like can be suppressed. Furthermore, since the pellet is not enlarged, after the reduction process is completed, the obtained reduced product can be pushed out of the furnace using a recovery tool and discharged, and can be recovered efficiently. The removal of the reduced product will be described later.

  Although it does not specifically limit as a magnitude | size of a pellet, When making it spherical, it can shape | mold so that the diameter may be set to about 10 mm-30 mm. Moreover, when it is set as a rectangular parallelepiped shape, a cube shape, a column shape, etc., it can shape | mold so that a vertical and horizontal internal dimension may be about 500 mm or less in general. By forming the pellets in such a size, the reduction treatment is uniformly performed, and there is little variation and smelting with high productivity can be performed.

  After molding the mixture, the mixture may be dried. There is a case where a predetermined amount of moisture is contained in the mixture, and there is a concern that the mixture may be shattered when the internal moisture is vaporized and expanded due to a rapid temperature rise during the reduction treatment. From the viewpoint of preventing such expansion, a step of subjecting the molded mixture to a drying treatment can be provided.

  Specifically, in the drying treatment, for example, the treatment can be performed so that the solid content of the pellets is about 70% by weight and the moisture is about 30% by weight. For example, hot air of 150 ° C. to 400 ° C. is blown onto the pellets and dried.

  In addition, when it is a comparatively big pellet, the mixture before a drying process and after a drying process may have a crack and a crack. When the lump is large, even if the surface area is increased due to cracking or the like, the influence is slight and does not cause a big problem. For this reason, there is no particular problem even if there are cracks or the like in the molded pellets subjected to the reduction treatment.

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

<2-3. Reduction process>
(1) Reduction treatment In the reduction treatment step S3, the mixture formed through the mixture forming step S2 is charged into a reduction furnace and heated at a predetermined reduction temperature to perform a reduction treatment. By the reduction treatment in the reduction treatment step S3, a smelting reaction (reduction reaction) proceeds, and reduced metals and slag are generated.

  Specifically, the reduction treatment in the reduction treatment step S3 is performed using a reduction furnace, and the mixture (pellet) containing nickel oxide ore is reduced and heated by charging it into a reduction furnace heated to a predetermined reduction temperature. . In the reduction process using a reduction furnace, nickel oxide contained in nickel oxide ore, which is the raw ore, is reduced as completely as possible, while iron oxide contained in nickel oxide ore is partially reduced. Thus, a so-called partial reduction is performed to obtain the desired high nickel grade ferronickel.

  In the reduction treatment, for example, the nickel oxide ore and iron oxide in the mixture are first reduced and metalized in the vicinity of the surface of the pellet where the reduction reaction easily proceeds in a short time of about 1 minute, for example. Nickel alloy is also called “ferronickel”) to form a shell. On the other hand, in the shell, with the formation of the shell, the slag component in the container is gradually melted to form liquid phase slag. Thereby, in the mixture, ferronickel metal (hereinafter simply referred to as “metal”) and ferronickel slag (hereinafter simply referred to as “slag”) are separately formed.

  Further, when the mixture is sufficiently mixed and there is substantially no variation in composition, since the raw materials are in close contact with each other, the reduction reaction occurs uniformly. Therefore, it is not necessary to produce a metal shell as it has been said in the past, and to react and take a certain amount of time to homogenize the metal shell. Therefore, the production of the metal shell is not essential. That is, even if a metal shell cannot be formed, the reaction proceeds uniformly and ferronickel can be produced.

  In the reduction treatment step S3, the slag in the mixture is melted to form a liquid phase, but the metal and slag that have already been separated and produced by the reduction treatment do not mix with each other. And a mixed phase as a separate phase of slag solid phase. The volume of this mixture has shrunk to a volume of about 50% to 60% compared to the mixture to be charged.

  Although it does not specifically limit as temperature (reduction temperature) in a reduction process, It is preferable to set it as the range of 1200 to 1450 degreeC, and it is more preferable to set it as the range of 1300 to 1400 degreeC. By reducing in such a temperature range, a reduction reaction can be caused uniformly and ferronickel with suppressed quality variation can be generated. More preferably, by performing reduction at a reduction temperature in the range of 1300 ° C. or higher and 1400 ° C. or lower, a desired reduction reaction can be caused in a relatively short time.

  In the reduction treatment, the internal temperature of the reduction furnace is increased by a burner or the like until the reduction temperature is in the above-described range, and the temperature is maintained after the temperature rise.

(2) Configuration of Reduction Furnace FIG. 2 is a cross-sectional view of a reduction furnace used for the reduction treatment, and shows an example of the configuration. The reduction furnace 1 includes an inlet 11 for charging the pellet P to be reduced into the furnace space S, and an outlet 12 for discharging the reduced product obtained by the reduction process to the outside of the furnace. In addition, it is preferable that the hearth 13 and the furnace wall 14 of the reduction furnace 1 are comprised with the refractory brick.

  The reduction furnace 1 is heated to a temperature of about 1200 ° C. to 1450 ° C. (reduction temperature), for example, and the pellets P are charged into the heated furnace space S through the charging port 11. In the reduction furnace 1, the pellet P placed on the hearth 13 is subjected to a reduction process for a predetermined reduction time, and then the reduction product obtained by the reduction process is discharged from the furnace through the discharge port 12. Discharged.

  The reduction furnace 1 is provided with a collection tool 15. The recovery tool 15 is parallel to the surface of the hearth 13 of the reduction furnace 1 and has a shaft 15a that slides in a direction toward the discharge port 12 of the reduction furnace 1, and a hearth of the reduction furnace 1 provided at the tip of the shaft 15a. 13 and an extruding plate 15b for extruding the reduced product on 13. The shaft 15 a of the recovery tool 15 is configured to be inserted from the furnace wall 14 of the reduction furnace 1.

  The shaft 15a constituting the recovery tool 15 slides in the horizontal direction (direction of arrow F in FIG. 2) along the surface of the hearth 13 of the reduction furnace 1. The sliding movement of the shaft 15a may be performed manually or mechanically by a piston mechanism.

  The extrusion plate 15b that constitutes the recovery tool 15 is provided at the tip of the shaft 15a described above, and the surface of the plate-like body faces the reduction product present on the hearth 13, and the sliding of the shaft 15a is performed. To move horizontally along the surface of the hearth 13.

  The collection tool 15 is preferably made of a material that is durable for reduction treatment at high temperatures. Moreover, it is preferable that the collection | recovery tool 15 is installed in the reduction furnace 1 so that the atmosphere in the reduction furnace 1 may not change. For example, it is preferable that the gap is not generated between the shaft 15a of the recovery tool 15 and the main body (for example, the side wall) of the reduction furnace 1.

  The reduction furnace 1 may be one in which a hearth such as a moving hearth furnace rotates, but is preferably a reduction furnace in which the hearth is fixed. Thus, when using a fixed furnace, it is preferable to comprise the hearth 13 with the material excellent in heat resistance, and it is preferable that it is the hearth 13 comprised with the refractory brick. If the hearth 13 is at least a reduction furnace 1 composed of refractory bricks, it can withstand temperature conditions of 1500 ° C. or higher, and the reduction temperature (temperature at which the mixture is melted) can be raised to, for example, about 1450 ° C. it can. By performing the reduction treatment under such a reduction temperature condition, the reduction reaction time can be shortened. Also. The generated metal settles and is easily coarsened. This makes it easy to separate the slag and the metal, and the metal can be recovered more efficiently.

  Moreover, in the reduction furnace 1, since the hearth 13 is comprised with a refractory brick, it can prevent that the pellet P mounted on the hearth 13 reacts with the hearth 13, and a pellet. P welding or the like can be suppressed. Thereby, when the obtained reduced product is pushed out by the collection tool 15 and taken out, it is possible to prevent the work from becoming difficult, and to collect coarse metal efficiently, and to further stabilize the operation. .

  In addition, it is preferable that the furnace wall 14 of the reduction furnace 1 is also composed of refractory bricks.

(3) Recovery of reduced product In the present embodiment, the reduced product generated by the reduction process on the mixture in the reduction furnace 1 is extruded along the hearth 13 by the recovery tool 15 provided in the reduction furnace 1. It is characterized by being collected.

  As described above, in the recovery tool 15, the shaft 15a slides in the horizontal direction (in the direction of arrow F in FIG. 2) along the surface of the hearth 13 of the reduction furnace 1, and the shaft An extrusion plate 15b is provided at the tip of 15a. Therefore, when the extruded plate 15b moves parallel to the surface of the hearth 13 by the sliding of the shaft 15a, the reduced product located on the hearth 13 can be pushed out so as to face the plate surface of the extruded plate 15b. . In the present embodiment, the reduced product is pushed out of the furnace by moving the shaft 15a in the direction of the discharge port 12 and pushing the reduced product against the plate surface by the extrusion plate 15b.

  Thus, by pushing out the obtained reduction product from the hearth 13 using the recovery tool 15, the reduction product can be taken out at a stretch, and the time required for taking out the reduction product can be shortened. If it takes a long time to take out the reduced product, the residence time of the reduced product in the reduction furnace 1 varies, resulting in uneven generation of the reduced product metal, and ferronickel having a uniform metal quality. It may not be recovered. On the other hand, by using the recovery tool 15 to remove the obtained reductant at once, all the reductant can be discharged out of the furnace in a short time, and the residence time in the reduction furnace 1 varies. And ferronickel having uniform metal quality can be efficiently recovered.

  Moreover, according to such a method, the coarsened metal can be efficiently recovered, and as a result, it can be easily separated from slag and the metal recovery rate can be increased.

  Although it does not specifically limit as temperature at the time of collection | recovery of a reduced material, It is preferable to set it as 1350 degrees C or less, and it is more preferable to set it as 1250 degrees C or less. Thus, by setting the temperature at the time of recovery to 1350 ° C. or less, it is possible to reduce the cost and efficiently recover the reduced product. In particular, by setting the temperature at the time of recovery to 1350 ° C. or less, it is possible to more efficiently suppress the welding to the hearth 13 due to the melting of the reduced product while maximizing the reduction reaction, An efficient recovery operation can be performed. In addition, it is preferable that the minimum of the temperature at the time of collection shall be 1200 degreeC or more.

<2-4. Separation process>
In the separation step S4, the metal and slag generated in the reduction treatment step S3 are separated to recover the metal. Specifically, the metal phase is separated and recovered from a mixture (mixture) containing a metal phase (metal solid phase) and a slag phase (slag solid phase) obtained by reduction heat treatment on the mixture.

  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.

  Further, the obtained metal phase and slag phase can be easily separated because of poor wettability, and for example, a predetermined mixture with respect to the large mixture obtained by the treatment in the reduction treatment step S3 described above, The metal phase and the slag phase can be easily separated from the mixture by dropping with a drop or applying an impact such as applying a predetermined vibration during sieving.

  In this way, the metal phase is recovered by separating the metal phase and the slag phase.

  EXAMPLES Hereinafter, although the Example and comparative example of this invention are shown and demonstrated more concretely, this invention is not limited to the following Examples at all.

<< Examples 1-6, Comparative Examples 1-2 >>
[Mixing process]
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 weight, average particle size: about 200 μm), appropriate amount The mixture was mixed using a mixer while adding water. The carbonaceous reducing agent is 100% by mass of the total amount necessary for reducing nickel oxide (NiO) and iron oxide (Fe ₂ O ₃ ) contained in nickel oxide ore as raw material ore without excess or deficiency. In such a case, the content was 20%.

[Mixture molding process]
Next, the obtained mixture was granulated into a sphere using a bread granulator and sieved to a size of φ15.5 ± 1.5 mm.

[Reduction treatment process]
Next, the prepared mixture samples (10 in each test) were charged into a reduction furnace, and subjected to reduction treatment at respective reduction temperatures and reduction times shown in Table 4 below. As the reducing furnace, a furnace having a structure as shown in FIG. 2 in which the hearth and the furnace wall are made of refractory bricks was used.

  Each mixture sample to be subjected to the reduction treatment was dried by blowing hot air at 300 ° C. to 400 ° C. so that the solid content was about 70% by weight and the water content was about 30% by weight prior to the reduction treatment. Table 3 below shows the solid content composition (excluding carbon) of the sample after the drying treatment.

  Specifically, in Examples 1 to 6, a reduction furnace including a recovery tool as shown in FIG. 2 was used as the reduction furnace. The hearth of the reduction furnace was made of refractory bricks. In addition, after the reduction treatment, by sliding the shaft of the recovery tool provided from the side wall of the reduction furnace, by pushing out the reduced product obtained on the hearth by the extrusion plate connected to the tip of the shaft, It was discharged outside the furnace through a discharge port and collected.

On the other hand, in Comparative Examples 1 and 2, a furnace without a recovery tool is used as the reduction furnace, and when the reduced product after the reduction process is recovered, it is taken out along the guide provided in the furnace. It was. Note that the hearth of the reduction furnace is made of metal, and in Comparative Examples 1 and 2, there is a high possibility that the hearth of the reduction furnace and the mixture sample are welded by reaction and cannot be separated from the hearth and cannot be recovered. As a result, ash (the main component is SiO ₂ and ash containing a small amount of oxides such as Al ₂ O ₃ and MgO as other components) is spread over the metal hearth, and substantially contains oxidation. The mixture sample was charged under no nitrogen atmosphere.

  In all the test examples, after recovering the reduced product, it was quickly cooled to room temperature while flowing nitrogen and taken out into the atmosphere.

≪Evaluation≫
About the sample taken out after reduction heat processing, the nickel metal rate and the nickel content rate in a metal were analyzed and calculated with the ICP emission-spectral-analyzer (SHIMAZU S-8100 type | mold). Table 4 below also shows values calculated from the analysis results. In addition, the nickel metal rate was calculated | required by (1) type | formula, the nickel content rate in a metal was calculated | required by (2) type | formula, and calculated the average of a total of 10 reduction materials obtained for every test.
Nickel metal ratio = amount of Ni metalized in the mixture / (amount of all Ni in the pellet) × 100 (%) (1) Formula Nickel content in metal = amount of Ni metalized in the mixture ÷ (total amount of metalized Ni and Fe in the pellet) x 100 (%) (2) formula

  As shown in the results of Table 4, in Examples 1 to 6, since the reductant was pushed out and discharged out of the furnace using the collection tool provided in the reduction furnace, the reductant can be efficiently recovered. It was possible to produce metal with high productivity. Moreover, the nickel metal conversion rate and the nickel content in the metal were both high and good, and a high-quality metal could be produced.

  On the other hand, in Comparative Example 1, both the nickel metal conversion rate and the nickel content in the metal were lower than in the examples. This is thought to be due to the fact that it took time to take out the reduced product, resulting in uneven generation of metal and variations. Moreover, in Comparative Example 2, although the ash was spread over the hearth, the metal hearth reacted with the mixture sample, and the reduced product could not be recovered effectively.

DESCRIPTION OF SYMBOLS 1 Reduction furnace 11 Loading inlet 12 Outlet 13 Furnace floor 14 Furnace wall 15 Recovery tool 15a Shaft 15b Extrusion board

Claims (7)

A method of smelting oxide ore in which a mixture obtained by mixing an oxide ore and a carbonaceous reducing agent is placed on the hearth of a reduction furnace and subjected to reduction treatment in the reduction furnace,
A method for smelting oxide ore in which a reduction product produced by a reduction treatment on the mixture is recovered by being extruded along a hearth of the reduction furnace with a recovery tool provided in the reduction furnace. The collection tool is
A shaft that slides in a direction toward the discharge port of the reduction furnace in parallel with the surface of the hearth of the reduction furnace;
An extrusion plate that is provided at the tip of the shaft and extrudes a reduction product on the hearth of the reduction furnace;
With
The method for smelting ore oxide according to claim 1, wherein the reduced product on the hearth is pushed out of the furnace through the discharge port and recovered by the extrusion plate moved by sliding of the shaft of the recovery tool. . The smelting method of oxidized ore according to claim 1 or 2, wherein a reduction temperature in the reduction treatment is set to 1200 ° C or higher and 1450 ° C or lower. The method for refining oxide ore according to claim 3, wherein the reduced product is recovered at a temperature of 1350 ° C. or lower. The method for refining oxide ore according to any one of claims 1 to 4, wherein the oxide ore is nickel oxide ore. The method for refining oxide ore according to claim 1, wherein the reduced product contains ferronickel. A reduction furnace for performing a reduction treatment on a mixture obtained by mixing an oxide ore and a carbonaceous reducing agent,
A hearth on which the mixture is placed;
A recovery tool for recovering the reduced product generated on the hearth by the reduction treatment;
A discharge port for discharging the reduced product out of the furnace,
The collection tool is
An axis that slides in a direction toward the discharge port in parallel with the surface of the hearth;
An extrusion plate that is provided at the tip of the shaft and extrudes a reduction product on the hearth of the reduction furnace;
Having a reduction furnace.

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