Reduction furnace, reduction treatment unit, reduction treatment method, and nickel oxide ore smelting method

Abstract

To provide a box type reduction furnace formed by connecting a heat treatment unit and a storage unit of an object to be treated, in which input and output of the object to be treated can be efficiently performed while suppressing a temperature decrease inside the heat treatment unit.SOLUTION: When a damper 111 is closed, both dampers are arranged so that a region near a right end of a left damper member 112C and a region near a left end of a right damper member 112D overlap when viewed along an insertion direction of the object to be processed, and two or more left damper members 112C and / or right damper members 112D are arranged one on top of the other along a direction perpendicular to an opening / closing surface of the damper 111, and the damper 111 has a through hole 113 through which a handle 31 of the ladle 3 for charging the object to be treated is formed.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a reduction furnace, a reduction treatment method, and a method for smelting nickel oxide ore. More specifically, the present invention relates to a reduction furnace and a reduction treatment method suitable for carrying out a method for smelting nickel oxide ore in which ferronickel is produced by reducing a mixture of nickel oxide ore and a carbonaceous reductant. [Background technology]

[0002] In the smelting of nickel oxide ore to produce ferronickel, which is an alloy mainly composed of iron and nickel and is used as a raw material for stainless steel and special steel, a reduction process is carried out in which the nickel oxide ore is mixed with a carbonaceous reducing agent and the mixture is heat-treated to reduce it (see Patent Document 1).

[0003] One of the heating furnaces that can be used for the reduction treatment is a box-shaped reduction furnace (reduction furnace 1) as shown in Figures 1 and 2. In this reduction furnace 1, a box-shaped storage section 21 for the material to be treated is connected to the side of a box-shaped heat treatment section 11, and a damper (door) 111 is provided between the heat treatment section 11 and the storage section 21 for the material to be treated to block the flow of heat and gas in the furnace.

[0004] For example, in order to reduce a mixture of raw ore and a reducing agent, a ladle (a ladle 3 for introducing materials to be treated) as shown in Fig. 3 may be used to move the mixture from the storage section 21 for materials to be treated to the heat treatment section 11. During the reduction process, it is necessary to prevent a drop in temperature inside the heat treatment section 11. If it were possible to open the damper 111 and move the ladle 3 for introducing materials to be treated, including the raw ore and the reducing agent, into the heat treatment section 11, and then carry out the reduction process while keeping the ladle 3 for introducing materials to be treated inside the heat treatment section 11 and preventing a drop in temperature inside the heat treatment section 11, it would be possible to efficiently add or remove the materials to be treated or add a reducing agent during the reduction process as needed. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2019-39045 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a box-shaped reduction furnace in which a heat treatment section and a storage section for materials to be treated are connected, and to enable efficient loading and unloading of materials to be treated while suppressing a temperature drop inside the heat treatment section during the progress of reduction treatment. [Means for solving the problem]

[0007] The inventors discovered that the above problem could be solved by installing a left-right opening / closing damper between the heat treatment section and the treatment material storage section, which has a through hole that allows the handle of a ladle for adding the material to be treated to be inserted when closed, and by configuring the damper to consist of three or more damper members stacked in a direction perpendicular to the opening / closing surface, and thus completed the present invention.

[0008] (1) A reduction furnace comprising: a box-shaped heat treatment section that heats and reduces materials to be treated; and a box-shaped storage section for materials to be treated that is connected to the side of the heat treatment section via a damper; the damper being a left-right open / close type damper consisting of a plate-shaped left damper member and a plate-shaped right damper member; the left damper member and the right damper member being arranged so that, when the damper is closed, a region near the right end of the left damper member overlaps a region near the left end of the right damper member when viewed along the insertion direction of the materials to be treated; two or more of the left damper member and / or the right damper member being arranged in a stack along a direction perpendicular to the opening and closing surface of the damper; and the damper having a through hole through which the handle of a dipper for inserting materials to be treated can be inserted when the damper is closed.

[0009] According to the reduction furnace (1), in a box-shaped reduction furnace in which the heat treatment section and the storage section for the material to be treated are connected, it is possible to efficiently load and unload the material to be treated while suppressing a temperature drop inside the heat treatment section during the reduction treatment. This also makes it possible to save on the consumption of fuel gas to compensate for the temperature drop inside the furnace that occurs when the material to be treated is loaded and unloaded. In addition, by using the reduction furnace described in (1) or (2), it is possible to suppress the temperature rise inside the storage section for the material to be treated due to the high heat inside the heat treatment section during the reduction treatment compared to conventional products. This shortens the time required to cool the material to be treated in the storage section for the material to be treated, and prevents quality degradation due to reoxidation of the material to be treated.

[0010] (2) The reducing furnace according to (1), wherein the plate-shaped damper member constituting the left damper member and / or the right damper member is a member formed by connecting two plate-shaped members in a U-shape when viewed from above.

[0011] According to the reducing furnace of (2), when the same number of plate materials are arranged as damper members in the reducing furnace described in (1), multiple plate materials can be stacked using a substantially smaller number of parts. This simplifies the control of the opening and closing operation, which requires the interlocking of the movements of multiple members, making it easier to control the opening and closing operation and allowing the opening and closing operation to be performed more accurately and reliably.

[0012] (3) A reduction treatment unit comprising the reduction furnace described in (1) or (2) and a ladle for feeding the material to be treated, wherein the shape and size of the through hole are such that the handle of the ladle for feeding the material to be treated can be inserted therethrough and can be fitted together without any gaps.

[0013] According to the reduction treatment unit of (3), when the damper is closed in the reduction furnace described in (1) or (2), the shape and size of the inner edge of the through hole are precisely adapted to the shape and size of the outer edge of the handle of the ladle for feeding the material to be treated, which is inserted into the through hole, and these are configured as an integrated unit, thereby minimizing the gap that occurs around the through hole when the damper is closed, and further enhancing the effect of suppressing the temperature drop inside the heat treatment section.

[0014] (4) A reduction treatment method for performing reduction treatment using a reduction furnace described in (1) or (2), wherein raw ore and a reducing agent are inserted into the heat treatment unit while being placed on a treatment object placement section at the tip of a ladle for feeding the treatment object, and then the damper is closed with the handle of the ladle for feeding the treatment object inserted through the through hole, and the treatment object is heated while still placed on the treatment object placement section.

[0015] According to the reduction treatment method (4), by using the reduction furnace described in (1) or (2), it is possible to efficiently load and unload the treatment object while suppressing a temperature drop inside the heat treatment section during the reduction treatment. This also makes it possible to save on the consumption of fuel gas to compensate for the temperature drop inside the furnace that occurs when the treatment object is loaded and unloaded. In addition, by using the reduction furnace described in (1) or (2), it is possible to suppress the temperature rise inside the treatment object storage section due to the high heat inside the heat treatment section during the reduction treatment compared to conventional products. This shortens the time required to cool the treatment object in the treatment object storage section and prevents quality degradation due to reoxidation of the treatment object.

[0016] (5) A method for smelting nickel oxide ore, which produces ferronickel by heating and reducing a mixture containing nickel oxide ore as a raw material ore and the reducing agent while the mixture is placed on the treatment object placement section by the reduction treatment method described in (4).

[0017] According to the method for smelting nickel oxide ore of (5), by applying the reduction treatment method described in (4) to the smelting of nickel oxide ore, it is possible to improve the productivity and stability of the quality of ferronickel. [Effects of the Invention]

[0018] According to the present invention, in a box-shaped reduction furnace in which a heat treatment section and a storage section for a material to be treated are connected, the material to be treated can be efficiently taken in and out while suppressing a temperature drop inside the heat treatment section during the progress of reduction treatment. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a diagram illustrating the configuration of a heat treatment section that serves as a main body of a reducing furnace according to the present invention. [Figure 2] 1 is a diagram illustrating a configuration of a storage section for a material to be treated connected to a heat treatment section of a reducing furnace according to the present invention. [Figure 3] 1 is a diagram showing an example of the configuration of a ladle for feeding material to be treated. [Figure 4A] 1 is a diagram illustrating the configuration (closed state) of a damper of a reducing furnace according to the present invention. [Figure 4B] 1 is a diagram illustrating the configuration of a damper (open state) of a reducing furnace according to the present invention. [Figure 5] 1 is a diagram illustrating the configuration and arrangement of a damper in a reducing furnace according to the present invention. [Figure 6] 1 is a diagram illustrating the configuration and arrangement of a damper in an embodiment of a reducing furnace according to the present invention, in which a U-shaped damper member is used. [Figure 7] 1 is a diagram illustrating the configuration and arrangement of a damper in an embodiment of a reducing furnace according to the present invention, in which a plurality of U-shaped damper members are used. [Figure 8] FIG. 1 is a process diagram showing the flow of a method for smelting nickel oxide ore. DETAILED DESCRIPTION OF THE INVENTION

[0020] The following describes in detail an embodiment in which the reduction furnace, reduction treatment unit, and reduction treatment method of the present invention are applied to a method for smelting nickel oxide ore. However, the application of the present invention is not limited to the method for smelting nickel oxide ore, and the present invention can be used in various metal smelting processes that include the reduction treatment of raw ore, with appropriate modifications within the scope of the object of the present invention.

[0021] Furthermore, in recent years, ores with high nickel grade and few impurities have become scarce, and in order to produce high-quality ferronickel in the smelting of the above-mentioned nickel oxide ore, it is necessary to efficiently process various ores and accumulate data. The reducing furnace of the present invention can also be preferably used as a test furnace for conducting test operations to obtain such data. Details of the embodiment as a test furnace will be described separately below.

[0022] Hereinafter, first, an outline of a method for smelting nickel oxide ore, which is a suitable application target of the reduction furnace, reduction treatment unit, and reduction treatment method of the present invention and is one embodiment of the present invention, will be described, and then the reduction furnace, reduction treatment unit, and reduction treatment method of the present invention will be described in detail.

[0023] <Method for smelting nickel oxide ore> As shown in FIG. 8 as an example, nickel oxide ore smelting, which is a suitable process for applying the present invention, is a process that sequentially includes a mixing step S1 in which a raw material containing nickel oxide ore is mixed with a carbonaceous reducing agent, a mixture forming step S2 in which the resulting mixture is formed into a predetermined shape, a reduction step S3 in which the formed mixture (or the raw material ore and the reducing agent) is reduced and heated at a predetermined reduction temperature in a reduction furnace, and a recovery step S4 in which the metal generated in the reduction step S3 is separated from the slag and the metal is recovered.

[0024] The "method for smelting nickel oxide ore" of the present invention is a novel smelting process characterized in that, among the above steps, at least the reduction step S3 is carried out by the reduction furnace, reduction treatment unit, or reduction treatment method of the present invention. The above four steps (S1 to S4) will be described below, but the mixing step S1 and the mixture forming step S2 are not necessarily required steps in the "method for smelting nickel oxide ore" of the present invention. It is also possible to carry out the "method for smelting nickel oxide ore" of the present invention in an embodiment in which the raw ore and the reducing agent are charged into the reduction furnace without carrying out such treatment, and such an embodiment is also within the technical scope of the present invention.

[0025] [Mixing process] The mixing step S1 is a step of mixing raw material powders containing nickel oxide ore to obtain a mixture. The raw material nickel oxide ore may be limonite ore, saprolite ore, or the like. The carbonaceous reducing agent may be coal powder, coke powder, or the like.

[0026] [Mixture forming process] The mixture forming step S2 is a step of forming the mixture obtained in the mixing treatment step S1. Specifically, the mixture obtained by mixing the raw material powders is formed into lumps of a predetermined size or larger so that the mixture can be loaded, for example, in a stacked form, into a reduction furnace during the reduction treatment in the subsequent reduction step S3.

[0027] [Reduction process] The reduction step S3 is a step in which the mixture (molded product) obtained in the mixture molding step S2 is heated in a reduction furnace to cause a reduction reaction, thereby producing metal and slag from the nickel oxide ore. The temperature of the reduction treatment (reduction temperature) is preferably 1200°C or higher and 1500°C or lower, and more preferably 1250°C or higher and 1450°C or lower. By setting the reduction temperature within this range, the reduction reaction can be efficiently and reliably progressed, and ferronickel with the desired properties can be obtained. The reduction treatment method of the present invention, which is suitable for carrying out this reduction step S3, will be described in detail later.

[0028] [Recovery process] The recovery step S4 is a step of separating the metal and slag produced in the reduction step S3 to recover the metal. Specifically, the metal phase, i.e., ferronickel, is separated and recovered from a mixture (mixture) containing a metal phase (metal solid phase) and a slag phase (slag solid phase) obtained by subjecting the mixture filled in a container to a reduction heat treatment. Methods for separating the metal phase and the slag phase from the mixture of the metal phase and slag phase obtained as a solid include, for example, sieving to remove unnecessary substances, as well as methods such as separation by specific gravity and separation by magnetic force.

[0029] <Reduction furnace, reduction treatment unit> 1 and 2 is one example of a preferred embodiment of the reducing furnace of the present invention. The reducing furnace 1 is a box-shaped heating furnace including a box-shaped heat treatment section 11 that heats and reduces a treatment target, and a treatment target storage section 21 that is connected to an opening on the side of the heat treatment section 11 via a damper 111.

[0030] The reduction furnace 1 is mainly characterized in that a left-right opening / closing damper is installed between the heat treatment section and the storage section for the material to be treated, and has a through-hole formed therein through which the handle of a ladle for feeding the material to be treated can be inserted when the furnace is closed, and the damper is composed of three or more damper members stacked and arranged in a direction perpendicular to the opening / closing surface.

[0031] In this specification, the technical means for reduction treatment comprising a combination of the reducing furnace 1 of the present invention and the ladle 3 for introducing the material to be treated, which has a handle 31 shaped to fit snugly into the through-hole 113 formed in the reducing furnace 1, is referred to as a "reduction treatment unit."

[0032] [Reduction furnace] 1 and 2, the heat treatment section 11 of the reducing furnace 1 is provided with a damper 111, which is an openable and closable door that separates the inside and outside of the heat treatment section 11. Furthermore, as shown in Fig. 2, a treatment target storage section 21 is connected to the outside of the heat treatment section 11 via the damper 111. Furthermore, a heating burner 12 and an exhaust port 14 are provided inside the heat treatment section 11, similar to various known heating furnaces.

[0033] Furthermore, it is preferable that a base 13 is provided inside the heat treatment section 11 at a position on the floor adjacent to the installation position of the damper 111. The base 13 is not an essential component of the present invention, but is a platform for stably supporting the treatment object placement section 32, on which the treatment object, such as a mixture of raw ore and a reducing agent, is placed, at a desired position inside the heat treatment section 11.

[0034] 4A and 4B, the damper 111 is a door-like partition member that can be opened and closed and is composed of a combination of multiple plate-like damper members 112C and 112D. The damper 111 has a through-hole 113 formed therein, through which the handle 31 of the treatment-material-introducing dipper 3 (FIG. 3) can be inserted and fitted without any gaps when in the closed state shown in FIG. 4A. The inner diameter of the through-hole 113 satisfies the above-mentioned requirement for the thickness of the handle 31 of the treatment-material-introducing dipper 3. To minimize the transfer of heat through the through-hole 113, the ratio of the area of ​​the through-hole to the area of ​​the opening connecting the heat treatment unit 11 and the treatment-material storage unit 21 is preferably 0.05 or less, and more preferably 0.03 or less. As an example, if the opening surface is a rectangular opening surface of 100 mm×130 mm, the inner diameter of through-hole 113 is preferably 28 mm or less, and more preferably 22 mm or less.

[0035] As shown in Figures 4A and 4B, when the opening surface connecting the heat treatment unit 11 and the treatment object storage unit 21 is divided into two left and right regions, the damper 111 is composed of a left damper member 112C that closes one region (the left region as seen from outside the heat treatment unit 11) and a right damper member 112D that closes the other region (the right region as seen from outside the heat treatment unit 11).When the damper 111 is closed, it is a left-right opening / closing damper (door) that forms a through hole 113 when viewed along the insertion direction of the treatment object.

[0036] 5 to 7, when the damper 111 is closed, the left damper member 112C is positioned so that the right-side near-tip region (the end region near the center of the damper) of the left damper member 112C overlaps the left-side near-tip region (the end region near the center of the damper) of the right damper member 112D when viewed along the insertion direction of the workpiece. The overlap width between the near-tip regions of the two dampers is not particularly limited, but should be 5 mm or more, preferably 10 mm or more, and more preferably 20 mm to 50 mm. By appropriately increasing this overlap width, it is possible to suppress the flow of radiant heat in and out of the gap between the near-tip regions.

[0037] 5 to 7, the damper 111 has two or more left and / or right damper members stacked along a direction perpendicular to the opening and closing surface of the damper 111. FIG. 5 shows an example of such an arrangement of damper members, and in the damper 111A of FIG. 5, two or more right damper members 112a and 112b are stacked along a direction perpendicular to the opening and closing surface of the damper 111. By arranging multiple damper members in this manner, it is possible to significantly suppress the flow of heat in and out due to convection through gaps between the regions near the tips of the dampers, and also to more reliably suppress the flow of radiant heat in and out through these gaps, thereby significantly reducing temperature changes due to the flow of radiant heat in and out.

[0038] In the damper 111 in which three or more damper members 112 are stacked as described above, the left damper member 112C and the right damper member 112D are each formed with slit-shaped cutouts 113C and 113D, each with a semicircular tip, for forming a through hole, as shown in Fig. 4B. This allows the through hole 113 to be formed in the manner described above when the damper 111 is closed.

[0039] As shown in FIGS. 6 and 7, the damper 111 can be configured using a member formed by connecting two plate-like members in a U-shape when viewed from above (hereinafter also referred to as a "U-shaped damper member") as the left and / or right damper members. Each damper shown in FIGS. 6 and 7 is an example of a damper configured using a "U-shaped damper member." In FIG. 6, one "U-shaped damper member" formed by connecting two plate members is arranged as the right damper member, and one damper member made of a single plate member is arranged as the left damper member. In this specification, in this case, two right damper members are arranged stacked along a direction perpendicular to the opening and closing surface of the damper 111. In addition, in FIG. 7, one "U-shaped damper member" is arranged as the right damper member, and one "U-shaped damper member" is also arranged as the left damper member. In this specification, in this case, it is assumed that two or more right-side damper members and two or more left-side damper members are stacked along a direction perpendicular to the opening / closing surface of the damper 111. By configuring the damper 111 using "U-shaped damper members," it is possible to stack multiple plate members using a substantially smaller number of parts when arranging the same number of plate members as the damper members. This simplifies the control of the opening / closing operation, which requires the linked movements of multiple members. Therefore, adding a substantial number of stacked damper members not only increases the effectiveness of suppressing the flow of heat, but also makes it easier to control the opening / closing operation, allowing for more accurate and reliable opening and closing operations.

[0040] Furthermore, various plate-shaped insulating boards having the heat resistance required depending on the conditions of use can be used as materials for the damper members 112 constituting the damper 111. As an example, if the reduction furnace 1 is used in the smelting of nickel oxide ore, it is preferable that the heat resistance temperature of the damper members 112 be 1500°C or higher. However, when reduction treatment is performed at such high temperatures, the temperature difference between the inside and outside of the heat treatment unit 11 becomes extremely large, so SiC dampers and ceramic dampers run the risk of cracking. Furthermore, even if a heat-resistant metal is used for a metal damper, there is a risk that it will quickly deteriorate due to melting, softening, or oxidation to the point where it becomes unusable. A material that is less susceptible to these risks is an alumina fiber insulating board with a density of 250 kg / m. 3 The above-mentioned heat insulating boards can be particularly preferably used as the material for each damper member 112 that constitutes the damper 111. By using such heat insulating boards as the material for the damper members, processing for forming appropriate through holes can be easily performed. Furthermore, by using the above-mentioned heat insulating boards, the weight of the entire damper 111 is reduced, making it easier to open and close.

[0041] In the reduction furnace 1 having the above-described configuration, the material to be treated is charged from the storage section 21 for the material to be treated to the heat treatment section 11 and removed from the heat treatment section 11 to the storage section 21 for the material to be treated by quickly inserting and removing the material to be treated into and from the heat treatment section 11 through the damper 111 with the damper 111 open, as shown in FIG. 4B .

[0042] The reduction treatment of the object to be treated in the reduction furnace 1 is performed with the damper 111 closed, as shown in Fig. 4A. More specifically, as shown in Figs. 5 to 7, this reduction treatment is performed by closing the damper 111 while the object to be treated placement portion 32 of the object to be treated introduction ladle 3 remains inserted inside the heat treatment unit 11, and heating the object to be treated placed on the placement surface 321 of the object to be treated placement portion 32. At this time, the damper 111 is closed with the handle 31 of the object to be treated introduction ladle 3 inserted through the through-hole 113 of the damper 111 and tightly fitted together.

[0043] The treatment object storage section 21 is connected to the thermal treatment section 11 via a damper 111. The treatment object storage section 21 is provided with a loading / unloading port 212 for loading and unloading the "treatment object" at a position opposite the damper 111. The loading / unloading port 212 is a lid and has a door-like structure that can be opened and closed. The loading / unloading port 212 is preferably a double-layered door to minimize air intrusion. When the "treatment object" is loaded into the treatment object storage section 21, the loading / unloading port 212 is opened, and during the reduction treatment in the thermal treatment section 11, the supply of a reducing agent in the treatment object storage section 21, and the cooling in the treatment object storage section 21, each operation is performed with the loading / unloading port 212 closed.

[0044] It is more preferable that the treatment object storage section 21 has a structure capable of replacing the atmospheric gas. The replacing gas is preferably an inert gas. By flowing an inert gas to replace the atmosphere, when the reduced treatment object is cooled in the treatment object storage section 21, the circulating inert gas acts as a cooling gas, further promoting cooling. Using an inert gas as the atmospheric gas inside the treatment object storage section 21 can also suppress oxidation of the reduced treatment object. Nitrogen, argon, etc. can be used as the inert gas because they are relatively inexpensive and readily available. Carbon dioxide can also be used as the inert gas. Furthermore, by flowing an inert gas inside the treatment object storage section 21, the temperature rise inside the treatment object storage section 21 caused by heat convection through the through-holes 113 can be further suppressed.

[0045] Furthermore, an "auxiliary damper (not shown)" can be provided at the opening of the treatment object storage section 21 on the thermal treatment section 11 side, separate from the damper 111, to completely close the opening without forming the through-hole 113 described above. When this "auxiliary damper" is provided in the reduction furnace 1, the "auxiliary damper" is opened when the treatment object placement section 32 of the treatment object introduction ladle 3 is inserted inside the thermal treatment section 11, and closed when the treatment object introduction ladle 3 is removed outside the thermal treatment section 11. This achieves the basic effect of the present invention, namely, efficient introduction and removal of treatment objects while suppressing a temperature drop inside the thermal treatment section during the reduction treatment, while further suppressing a temperature rise inside the treatment object storage section 21, including when the treatment object introduction ladle 3 is removed outside the thermal treatment section 11.

[0046] [Reduction Processing Unit] The reduction treatment unit of the present invention is, for example, a technical means for implementing reduction treatment, which is a combination of a reduction furnace 1 according to the present invention shown in FIGS. 1 and 2 and a ladle 3 for introducing materials to be treated shown in FIG. 3. In this reduction treatment unit, the shape and size of the inner edge of a through hole 113 formed in a damper 111 of the reduction furnace 1 are optimized so that they are equal to the shape and size of a cross section of the handle 31 of the ladle 3 for introducing materials to be treated that is perpendicular to the central axis (i.e., the outer edge of the shaft). As a result, in the reduction treatment unit, as shown in FIGS. 5 to 7, the handle 31 of the ladle 3 for introducing materials to be treated can be inserted into the through hole 113 when the damper 111 is closed, and in this state, the through hole 113 and the handle 31 of the ladle 3 for introducing materials to be treated can be fitted together without any gaps. This allows efficient introduction and removal of materials to be introduced while suppressing a temperature drop inside the heat treatment unit during the reduction treatment.

[0047] (Ladle for adding materials to be treated) FIG. 3 is a diagram showing the configuration of a treatment object feeding ladle 3 constituting a reduction treatment unit of the present invention. The treatment object feeding ladle 3 includes a handle 31 and a treatment object placement portion 32 connected to the tip of the handle 31. The handle 31 is a rod-shaped part that is held by an operator's hand or by a machine. The treatment object placement portion 32 is connected to the tip of the handle 31, and the treatment object is placed on its upper surface (placement surface 321). Note that FIG. 3 shows an example of an embodiment in which the treatment object placement portion 32 is rectangular parallelepiped-shaped. However, the shape of the treatment object placement portion is not limited to this. The placement surface may be recessed, with walls on all four sides, and may be configured like a container with an open top. The treatment object feeding ladle 3 can be made of various ceramics having a certain level of heat resistance depending on the conditions of use. However, alumina ceramics or magnesia ceramics are particularly preferred. <Reduction treatment method> The "reduction treatment method" of the present invention (hereinafter simply referred to as the "reduction treatment method") is a method for performing a reduction treatment on a treatment object using the reduction furnace 1 or the above-mentioned "reduction treatment unit" configured to include the reduction furnace 1. An example of a specific procedure for this "reduction treatment method" will be described below.

[0048] In the "reduction treatment method," first, the loading / unloading port 212 of the treatment object storage section 21 is opened and the material is loaded into the treatment object storage section 21, and then the damper 111 is opened and the material is loaded into the heat treatment section 11 connected to the treatment object storage section 21 and placed on the base 13.

[0049] At this time, the treatment object feeding ladle 3 placed in the heat treatment unit 11 is moved to near the center of the base 13, and then the treatment object feeding ladle 3 itself is placed on the base 13, and the reduction treatment is started in this state (with the treatment object feeding ladle 3 containing the treatment object (hereinafter simply referred to as "treatment object"), such as raw ore and reducing agent, still placed on it). That is, during the reduction treatment, heating is started while the treatment object feeding ladle 3 remains in the heat treatment unit 11. According to this method, the reduction treatment can be performed simply by placing the treatment object on the treatment object feeding ladle 3 and then moving the treatment object feeding ladle 3 into and out of the heat treatment unit 11 via the treatment object storage unit 21. This shortens the opening time of the damper 111 when the treatment object is taken into and out of the heat treatment unit 11, thereby suppressing a temperature drop inside the heat treatment unit 11 while the damper 111 is open. Furthermore, it is possible to prevent erroneous operations such as the "object to be treated" falling off the base 13 when transferring the "object to be treated" from the ladle 3 for feeding the object to be treated onto the base 13, and to prevent problems such as uneven heating by the burner 12. In this embodiment, ash, a carbonaceous reducing agent, or the like may be laid on the object to be treated placing portion 32 of the ladle 3 for feeding the object to be treated. This makes it possible to prevent the "object to be treated" from fusing to the placing surface of the object to be treated placing portion 32.

[0050] Furthermore, when the ladle 3 for introducing the material to be treated is left in the heat treatment section 11, the main part of the handle 31 of the ladle 3 for introducing the material to be treated is located in the storage section 21 for the material to be treated (see FIG. 2). By starting the reduction treatment with the handle 31 of the ladle 3 for introducing the material to be treated located in the storage section 21 for the material to be treated, it is possible to prevent the handle 31 of the ladle 3 for introducing the material to be treated from being thermally deformed by the heat of the reduction treatment.

[0051] Furthermore, in the "reduction treatment method," the "object to be treated" can also be moved from the thermal treatment section 11 to the object to be treated storage section 21 during the reduction treatment. In this case, after opening the damper 111, the handle 31 of the object to be treated feeding ladle 3 is grasped and the object to be treated feeding ladle 3 is pulled out from the object to be treated storage section 21 side, thereby moving the portion of the object to be treated mounting section 32 on which the "object to be treated" is placed into the object to be treated storage section 21, and the damper 111 is quickly closed. Then, necessary additional work, such as adding more carbonaceous reducing agent to the "object to be treated" placed on the object to be treated mounting section 32, can be appropriately performed inside the object to be treated storage section 21. In this way, the "object to be treated" can be moved smoothly and reliably between the thermal treatment section 11 and the object to be treated storage section 21 by moving the object to be treated feeding ladle 3.

[0052] After the reduction treatment is completed, the damper 111 is opened from inside the treatment object storage section 21, and the reduced material obtained by the reduction treatment is removed from the heat treatment section 11 via the treatment object storage section 21. When removing the reduced material, the reduced material is cooled in the treatment object storage section 21. The cooling of the reduced material in the treatment object storage section 21 is performed with the damper 111 closed from inside the treatment object storage section 21. This prevents high-temperature heat from the heat treatment section 11 from entering the treatment object storage section 21, allowing for efficient cooling.

[0053] Furthermore, since the storage section 21 for the material to be treated is connected continuously to the heat treatment section 11, the reduced material obtained by the reduction treatment in the heat treatment section 11 can be cooled without being taken out into the atmosphere. If the reduced material heated to a high temperature is taken out into the atmosphere as is, oxidation of the generated metal will proceed rapidly, resulting in a deterioration in the metal properties and a significant decrease in the metal recovery rate. In this regard, by performing the reduction treatment using a reduction furnace 1 in which the storage section 21 for the material to be treated is connected to the heat treatment section 11, the cooling operation for the high-temperature reduced material can be efficiently performed in the storage section 21 for the material to be treated, and oxidation of the metal can be effectively prevented. <Example of trial operation>

[0054] The "reduction furnace," "reduction treatment unit," and "reduction treatment method" of the present invention can all be preferably used as technical means for conducting trial operations of reduction treatment with the aim of obtaining various data to be reflected in the packaging industry, including reduction treatment. For example, a small amount of pellets can be charged into the reduction furnace 1, reduction treatment is performed, and the generated reduced product is removed to obtain the various data described above.

[0055] Not only reducing furnaces, but furnaces in general require an opening for the introduction and removal of processed products such as samples. The size of the opening is preferably small to prevent oxygen entrainment, heat diffusion, the influence of external air, and the like. However, particularly when a relatively small-scale furnace is used for test operations, the size of the opening becomes relatively large, which can cause errors in the data obtained from the test. To address this issue, the present invention can be applied to use the reducing furnace 1 as a test furnace, ensuring a sufficient opening size while suppressing sudden temperature changes. This allows accurate data on the reduction status in the furnace to be obtained and reflected in operations. [Example]

[0056] The present invention will be explained in more detail below by showing examples, but the present invention is not limited to the following examples in any way.

[0057] [Example] A test operation of reduction treatment was carried out in accordance with the procedure of the above-described "reduction treatment method" of the present invention, using a "reduction treatment unit" including a reduction furnace and a ladle for feeding a material to be treated, each having a shape and configuration similar to that of reduction furnace 1 having the configuration shown in FIGS. 1 and 2 and ladle 3 for feeding a material to be treated shown in FIG. 3, with a mixture of nickel oxide ore and a carbonaceous reducing agent as the material to be treated.

[0058] (Reduction furnace and ladle for feeding materials to be treated (reduction treatment unit)) The shape and arrangement of the dampers in the reducing furnace 1 used in the examples were as shown in Fig. 7 for Example 1, Fig. 6 for Example 2, and Fig. 5 for Example 3. In the above-mentioned reducing furnace, the size of the opening of the heat treatment section closed by the damper was 130 mm × 100 mm, and the outer diameter of the ladle for introducing the material to be treated and the inner diameter of the through-hole formed when the damper was closed were both 20 mm.

[0059] (Reduction treatment method) The specific procedure for the example was as follows. First, the object to be treated, placed on the ladle for feeding the object to be treated, was inserted into the heat treatment unit by moving the ladle while it was still placed on the support surface. With the object to be treated still on the support surface and the handle of the ladle for feeding the object to be treated inserted through the through-hole formed when the damper was closed, the damper was closed and reduction treatment was performed under heating conditions of 1400°C x 30 minutes. The damper was then opened, and the object to be treated that had undergone reduction treatment, still placed on the ladle for feeding the object to be treated and still on the support surface, was moved to the storage unit for the object to be treated by moving the ladle for the object to be treated. The reduced object to be treated was cooled in the same chamber for 15 minutes with the damper closed before being removed into the atmosphere. Nitrogen was constantly flowing through the storage unit for the object to be treated.

[0060] The reduction-treated material obtained in the test operation of the example was subjected to composition analysis, and the nickel metallization rate, defined by the following formula (1), was calculated using an ICP optical emission spectrometer (SHIMAZU S-8100). The results are shown in Table 1. (Equation 1) Nickel metallization rate = amount of metallized Ni in the mixture ÷ (total amount of Ni in the mixture) × 100 (%)

[0061] [Table 1]

[0062] Here, the "Ni metallization rate" required in a typical nickel oxide ore smelting process, including reduction treatment of nickel oxide ore, is usually about 97 to 99%. In the test operation of the example, a sufficient "Ni metallization rate" was maintained, and all of the "treatment object" between the heat treatment section and the treatment object storage section was easily carried out by simply moving the treatment object input ladle approximately parallel, so that no treatment object fell off the loading surface and each movement could be completed quickly.

[0063] From the above, it has been confirmed that, according to the present invention, in a box-shaped reduction furnace in which a heat treatment section and a storage section for the material to be treated are connected, it is possible to efficiently take in and out the material to be treated while suppressing a temperature drop inside the heat treatment section during the progress of reduction treatment. [Explanation of symbols]

[0064] 1. Reduction furnace 11 Heat treatment section 111 Damper 112 (112A~D) Damper member 113 Through hole 113C, 113D Notch for forming through hole 12 burners 13 Foundation 14 Exhaust port 21 Storage section for material to be treated 212 Loading / unloading port 3. Ladle for feeding materials to be treated 31 patterns 32 Processing object placement section 321 Placement surface S1 Mixing process S2 Mixture formation process S3 Reduction step S4 Recovery process

Claims

1. a box-shaped heat treatment section for heating and reducing the treatment object; a box-shaped storage unit for the material to be treated connected to a side surface of the heat treatment unit via a damper; Equipped with the damper is a left-right open / close type damper composed of a plate-shaped left damper member and a plate-shaped right damper member, and when the damper is closed, the left damper member and the right damper member are arranged so that a right-side front end vicinity region of the left damper member overlaps with a left-side front end vicinity region of the right damper member when viewed along the insertion direction of the workpiece, Two or more of the left damper member and / or the right damper member are stacked and arranged along a direction perpendicular to the opening and closing surface of the damper, The damper has a through hole formed therein through which the handle of a ladle for inserting the material to be treated can be inserted when the damper is closed. Reduction furnace.

2. The plate-shaped damper member constituting the left damper member and / or the right damper member is a member formed by connecting two plate-shaped members in a U-shape when viewed from above. The reduction furnace according to claim 1 .

3. A reduction treatment unit comprising the reduction furnace according to claim 1 or 2 and a ladle for introducing a material to be treated, The shape and size of the through hole are such that the handle of the ladle for inserting the material to be treated can be inserted therethrough and can be fitted together without any gaps. Reduction processing unit.

4. A reduction treatment method using the reduction furnace according to claim 1 or 2, comprising: The raw ore and the reducing agent are placed as the material to be treated on a treatment object placing portion at the tip of a ladle for feeding the material to be treated, and the material is then inserted into the heat treatment unit, and the damper is closed with the handle of the ladle for feeding the material to be treated inserted through the through-hole, and the material to be treated is heated while still placed on the treatment object placing portion. Reduction treatment method.

5. 5. The reduction treatment method according to claim 4, wherein a mixture containing nickel oxide ore as a raw material ore and the reducing agent is heated and reduced while being placed on the treatment object placement section, thereby producing ferronickel. A method for smelting nickel oxide ore.

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