Method for separating and recovering rare earth components and metal components from unsintered waste before manufacturing degreasing or from unsintered waste after manufacturing degreasing

Abstract

Provides is a method for separating and recovering rare earth components and metal components from unsintered waste.　The method for separating and recovering includes: (A) a step for preparing unsintered waste before manufacturing degreasing containing a magnetic metal powder, a ceramic powder, a rare earth powder, and a resin component, the metal powder and the ceramic powder being at least partially adhered to each other; (B) a step for pulverizing the unsintered waste before manufacturing degreasing; (C) a step for using a magnet after step (B) to separate and recover a metal powder-containing substance and a rare earth powder-containing substance; (H) a step for recovering a metal component constituting the metal powder from the metal powder-containing substance through electrolytic refining; and (E) a step for recycle degreasing the resin component from the unsintered waste before manufacturing degreasing between steps (A) and (H) and after step (C).

Description

Method for separating and recovering rare earth and metal components from unburned waste before or after degreasing

[0001] The present invention relates to a method for separating and recovering rare earth elements and metal elements from unfired waste before degreasing in the manufacturing process of a multilayer ceramic capacitor or from unfired waste after degreasing in the manufacturing process.

[0002] Significant demand is expected for multilayer ceramic capacitors (MLCCs) as electronic components for automobiles, mobile phones, and the like. A multilayer ceramic capacitor includes a laminate having internal electrode layers and ceramic layers, and an external electrode. The internal electrode layers contain a metal component such as Ni, and the ceramic layers are formed from BaTiO3, for example. Patent Documents 1 to 4 disclose methods for recovering Ni, which is primarily used in the internal electrode layers, and also disclose that BaTiO3 contained in the ceramic layers is separated during the Ni recovery process.

[0003] Japanese Patent Application Laid-Open No. 2003-253347 Japanese Patent Application Laid-Open No. 2003-268459 Japanese Patent Application Laid-Open No. 2003-277843 Japanese Patent Application Laid-Open No. 2003-277846

[0004] Here, some raw materials used to manufacture multilayer ceramic capacitors contain not only Ni but also rare earth elements. Patent Documents 1 to 4 disclose the recovery of Ni, but do not disclose the recovery of rare earth elements. However, it is desirable to be able to recover not only metal elements such as Ni but also rare earth elements.

[0005] Therefore, a primary object of the present invention is to provide a method for separating and recovering rare earth components and metal components from unfired waste before degreasing or unfired waste after degreasing, which is discharged in the manufacturing process of a multilayer ceramic capacitor.

[0006] The method for separating and recovering rare earth components and metal components from unfired waste before degreasing according to the present invention comprises: (A) a step of preparing unfired waste before degreasing, which is unfired waste before firing of laminated chips discharged in the manufacturing process of a multilayer ceramic capacitor, the unfired waste before degreasing, the unfired waste before degreasing, containing magnetic metal powder, ceramic powder, rare earth powder, and a resin component, with the metal powder and ceramic powder at least partially adhering to each other; (B) a step of micronizing the unfired waste before degreasing; (C) a step of separating and recovering the unfired waste before degreasing after step (B) using a magnet into a metal powder-containing material containing metal powder and ceramic powder, and a rare earth powder-containing material containing rare earth powder and ceramic powder; and (H) a step of recovering metal components constituting the metal powder from the metal powder-containing material after step (C) by electrolytic refining.

[0007] According to this invention, rare earth elements and metal elements can be separated and recovered from unburned waste before production and degreasing.

[0008] The method for separating and recovering rare earth components and metal components from unfired waste after manufacturing and degreasing according to the present invention comprises: (A) a step of preparing unfired waste after manufacturing and degreasing, which is unfired waste before firing of laminated chips discharged in the manufacturing process of a multilayer ceramic capacitor, the unfired waste after manufacturing and degreasing containing magnetic metal powder, ceramic powder, and rare earth powder, with the metal powder and ceramic powder at least partially adhering to each other, and from which resin components have been degreased in the manufacturing process; (B) a step of pulverizing the unfired waste after manufacturing and degreasing; (C) a step of separating and recovering the unfired waste after manufacturing and degreasing after step (B) using a magnet into a metal powder-containing material containing metal powder and ceramic powder, and a rare earth powder-containing material containing rare earth powder and ceramic powder; and (H) a step of recovering the metal components that make up the metal powder from the metal powder-containing material after step (C) by electrolytic refining.

[0009] According to this invention, rare earth elements and metal elements can be separated and recovered from the unburned waste after production and degreasing.

[0010] According to the present invention, it is possible to provide a method for separating and recovering rare earth elements and metal elements from unfired waste before degreasing in the manufacturing process of a multilayer ceramic capacitor or from unfired waste after degreasing in the manufacturing process.

[0011] The above and other objects, features, and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments of the present invention, which proceeds with reference to the accompanying drawings.

[0012] 1 is a flow chart showing a separation and recovery method for separating and recovering rare earth components and metal components from unfired waste before firing (firing of laminated chips) and before production degreasing, which is discharged in a manufacturing process of a multilayer ceramic capacitor, according to an embodiment of the present invention. FIG. 2 is a configuration diagram of an electrolytic refining system. FIG. 3 is an external perspective view showing an example of a multilayer ceramic capacitor according to an embodiment of the present invention. FIG. 4 is a cross-sectional view taken along line III-III in FIG. 2. FIG. 5 is a cross-sectional view parallel to a plane including the length direction and lamination direction of a laminated chip. FIG. 6 is an enlarged view of a portion α in FIG. 4, and is a schematic diagram showing the states of various powders. FIG. 7 is a flow chart showing a separation and recovery method for separating and recovering rare earth components and metal components from unfired waste after production degreasing, before firing (firing of laminated chips), which is discharged in a manufacturing process of a multilayer ceramic capacitor and which has been production degreased in the manufacturing process.

[0013] In this embodiment, a separation and recovery method for separating and recovering rare earth components and metal components from unfired waste before firing of laminated chips discharged in the manufacturing process of multilayer ceramic capacitors will be described. Furthermore, the unfired waste will be divided into unfired waste before firing of laminated chips and before manufacturing degreasing, and unfired waste before firing of laminated chips and after manufacturing degreasing. In this embodiment, first, a separation and recovery method for unfired waste before firing of laminated chips and before manufacturing degreasing will be described, and then a separation and recovery method for unfired waste before firing of laminated chips and after manufacturing degreasing will be described. In this embodiment, unfired waste before firing of laminated chips and before manufacturing degreasing may be referred to as unfired waste before manufacturing degreasing. Furthermore, unfired waste before firing of laminated chips and after manufacturing degreasing may be referred to as unfired waste after manufacturing degreasing.

[0014] 1. Unfired waste before firing of laminated chips and before degreasing during production 1.1. Separation and recovery method for unfired waste before firing of laminated chips and before degreasing during production A method for separating and recovering rare earth components and metal components from unfired waste before firing of laminated chips and before degreasing during production, which is discharged in the manufacturing process of a multilayer ceramic capacitor, according to an embodiment of the present invention, will be described.

[0015] Fig. 1A is a flow diagram showing a separation and recovery method according to an embodiment of the present invention for separating and recovering rare earth components and metal components from unfired waste before firing (firing of laminated chips) and before degreasing, which is discharged in the manufacturing process of a multilayer ceramic capacitor. Fig. 1B is a configuration diagram of an electrolytic refining system. In this separation and recovery method, unfired waste before firing of laminated chips and before degreasing, which is discharged in the manufacturing process of a multilayer ceramic capacitor, is used as the starting point for separation and recovery. The unfired waste before degreasing will now be described.

[0016] (1) Unburned Waste Before Degreasing in Manufacturing Before explaining the unburned waste before degreasing in manufacturing, the multilayer ceramic capacitor manufactured in the manufacturing process for the multilayer ceramic capacitor and the manufacturing process thereof will be described below.

[0017] (1-1) Multilayer Ceramic Capacitor Fig. 2 is an external perspective view showing an example of a multilayer ceramic capacitor according to a first embodiment of the present invention. Fig. 3 is a cross-sectional view taken along line III-III in Fig. 2. Here, a two-terminal multilayer ceramic capacitor will be described as an example of the multilayer ceramic capacitor 10.

[0018] As shown in FIGS. 2 and 3 , the multilayer ceramic capacitor 10 includes, for example, a rectangular parallelepiped laminate 12 and external electrodes 30 disposed on both ends of the laminate 12 .

[0019] The laminate 12 has a plurality of stacked ceramic layers 14 and a plurality of internal electrode layers 16 stacked on the ceramic layers 14. Furthermore, the laminate 12 has a first main surface 12a and a second main surface 12b facing each other in a height direction (stacking direction) x, a first side surface 12c and a second side surface 12d facing each other in a width direction y perpendicular to the height direction x, and a first end surface 12e and a second end surface 12f facing each other in a length direction z perpendicular to the height direction x and the width direction y. The ceramic layers 14 and the internal electrode layers 16 are stacked in the height direction x.

[0020] The first internal electrode layer 16 a and the second internal electrode layer 16 b can be made of a conductive material containing, for example, a magnetic metal, which may be a simple metal or an alloy. Examples of the magnetic metal include Ni and Fe.

[0021] The ceramic layer 14 can be formed, for example, from a dielectric material. Examples of such dielectric materials include perovskite-type compounds containing BaTiO3, CaTiO3, SrTiO3, or CaZrO3 as their main component and dielectric ceramics having a perovskite structure. When the dielectric material is the main component, a rare earth element is added to the dielectric material as an additive depending on the desired characteristics of the laminate 12. Examples of the rare earth element to be added include at least one of Dy, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb, and Lu. The dielectric material may also contain a minor component, such as a Mn compound, an Fe compound, a Cr compound, a Co compound, or a Ni compound, in a smaller amount than the main component. Furthermore, at least one of Si, Mg, Ba, and Mn may be added as an additive to the above-mentioned main components, but these minor components and additives may be omitted because they may cause a decrease in the quality of the rare earth components during separation and recovery of the rare earth components.

[0022] As shown in FIGS. 2 and 3, external electrodes 30 are disposed on the first end face 12e side and the second end face 12f side of the laminate 12.

[0023] The external electrode 30 includes a first external electrode 30a and a second external electrode 30b. The first external electrode 30a is connected to the first internal electrode layer 16a and is disposed on at least the surface of the first end face 12e. The second external electrode 30b is connected to the second internal electrode layer 16b and is disposed on at least the surface of the second end face 12f.

[0024] The external electrode 30 includes a base electrode layer 32 containing a metal component and a plating layer 34 disposed on the base electrode layer 32. The first external electrode 30a includes a first base electrode layer 32a and a first plating layer 34a. The second external electrode 30b includes a second base electrode layer 32b and a second plating layer 34b.

[0025] The base electrode layer 32 may be formed from a baking layer containing a glass component and a metal component. The metal component of the baking layer may include, for example, at least one selected from Cu, Ni, Ag, Pd, an Ag-Pd alloy, Au, etc. The glass component of the baking layer may include, for example, an oxide containing at least one element selected from B, Si, Ba, Mg, Al, Li, etc. Alternatively, the base electrode layer 32 may be formed from a thermosetting resin and a conductive resin layer containing a metal component. Examples of the metal contained in the conductive resin layer include Ag, Cu, Ni, Sn, Bi, or an alloy containing any of these. Examples of the thermosetting resin include various known thermosetting resins such as epoxy resin and phenoxy resin.

[0026] The plating layer 34 contains at least one selected from, for example, Cu, Ni, Sn, Ag, Pd, an Ag—Pd alloy, Au, and the like.

[0027] (1-2) Method for Manufacturing the Multilayer Ceramic Capacitor Next, a method for manufacturing the multilayer ceramic capacitor 10 will be described.

[0028] (Step 1) First, a dielectric sheet for the ceramic layer and a conductive paste for the internal electrode layer are prepared. The dielectric sheet for the ceramic layer is formed from a dielectric slurry containing, but not limited to, BaTiO3 as a main component and Dy as an additive. The conductive paste for the internal electrode layer is formed from, but not limited to, Ni as a main component. The dielectric sheet and the conductive paste for the internal electrode layer include a binder and a solvent. The binder and solvent contain a resin component, and various known thermosetting resins such as epoxy resin, phenoxy resin, phenolic resin, urethane resin, and polyimide resin can be used as the resin component. Note that inorganic elements such as Si are difficult to remove even by degreasing (including degreasing during production degreasing and recycling degreasing). These inorganic elements remain as contaminants in the unfired waste before degreasing, adversely affecting the separation and recovery of rare earth and metal components. Therefore, it is preferable that the resin component does not contain inorganic elements such as Si that are difficult to remove by degreasing (including degreasing during production degreasing and recycling degreasing).

[0029] (Step 2) Then, a conductive paste for the internal electrode layers is printed in a predetermined pattern on the dielectric sheet by, for example, screen printing, gravure printing, etc. In this way, a dielectric sheet on which the pattern of the first internal electrode layer is formed, and a dielectric sheet on which the pattern of the second internal electrode layer is formed are prepared.

[0030] Furthermore, with regard to the dielectric sheets, outer layer dielectric sheets on which no internal electrode layer patterns are printed are also prepared.

[0031] A predetermined number of dielectric sheets for outer layers, on which no pattern of internal electrode layers is printed, are stacked. A dielectric sheet on which a pattern of a first internal electrode layer is printed and a dielectric sheet on which a pattern of a second internal electrode layer is printed are sequentially stacked on top of the dielectric sheets to form a portion that will become an internal layer portion. A predetermined number of dielectric sheets for outer layers, on which no pattern of an internal electrode layer is printed, are stacked on top of the portion that will become an internal layer portion. This forms a laminated sheet having an internal layer portion and an external layer portion. The dielectric sheets may also be referred to as unfired ceramic layers, i.e., ceramic layers before firing of the laminated chip. The pattern of the internal electrode layers may also be referred to as unfired internal electrode layers, i.e., internal electrode layers before firing of the laminated chip.

[0032] (Step 3) Next, the laminated sheet is pressed in the lamination direction by means of a hydrostatic press or the like to produce a laminated block.

[0033] (Step 4) The laminated block is then cut to a predetermined size to produce the laminated chip 12_U. Figure 4 is a cross-sectional view of the laminated chip parallel to a plane including the longitudinal direction and the lamination direction. Figure 5 is an enlarged view of the α portion of Figure 4, showing the state of various powders. Figure 4 also shows a cross-sectional view of the laminated chip 12_U on which the external electrodes 30 have not yet been formed. The laminated chip 12_U in Figures 4 and 5 is in a state prior to the manufacturing degreasing step 5 and the firing step 6 of the laminated chip. However, the resin component contained in the laminated chip 12_U is not shown. As shown in Figures 4 and 5, the laminated chip 12_U is formed by alternately stacking unfired internal electrode layers 16_U and unfired ceramic layers 14_U.

[0034] (Step 5) Next, the resin components in the laminated chip 12_U are removed. Hereinafter, the removal of the resin components in step 5 is degreasing in the manufacturing process, and may be referred to as manufacturing degreasing. The degreasing temperature in manufacturing degreasing is, for example, higher than 800°C and lower than 1000°C.

[0035] (Step 6) Next, the laminated chip 12_U is fired to produce the laminate 12. The firing temperature for the laminated chip 12_U depends on the materials of the ceramic layers and internal electrode layers, which are dielectrics, but is preferably higher than 1000°C and lower than 1400°C, for example. Steps 1 to 6 constitute the laminate formation process. Note that the firing in step 6 may hereinafter be referred to as firing the laminated chip. Furthermore, this firing fires the unfired internal electrode layers 16_U and unfired ceramic layers 14_U, turning them into the internal electrode layers 16 and ceramic layers 14.

[0036] (Step 7) Next, the base electrode layer paste is applied to the first and second end faces 12e, 12f of the laminate 12 and fired to form the base electrode layer 32 of the external electrode 30. The firing temperature is preferably 700°C or higher and 900°C or lower.

[0037] (Step 8) Next, the plating layer 34 is formed on the base electrode layer 32. The plating layer 34 is formed, for example, by laminating a Ni plating layer and a Sn plating layer in this order on the base electrode layer 32.

[0038] The multilayer ceramic capacitor 10 is manufactured by the above-described manufacturing process.

[0039] Here, when the multilayer ceramic capacitor 10 is manufactured by the above-described manufacturing method for the multilayer ceramic capacitor 10, the unfired waste before manufacturing degreasing refers to waste that has not yet been degreased in (Step 5) of the manufacturing method for the multilayer ceramic capacitor 10 and waste before the firing of the laminated chips in (Step 6). In other words, the unfired waste before manufacturing degreasing refers to waste before (Step 5) and (Step 6). For example, the unfired waste before manufacturing degreasing refers to excess laminate blocks, such as scraps of laminate blocks, that are discharged after the laminate blocks are cut in (Step 4). Furthermore, the unfired waste before manufacturing degreasing refers to defective laminate chips that have been cut in (Step 4). Furthermore, the unfired waste before manufacturing degreasing refers to dielectric sheets on which patterns of internal electrode layers prepared in (Step 2) are formed. It is preferable that the PET film has been removed from the dielectric sheets. Furthermore, the unfired waste before manufacturing degreasing refers to defective laminate blocks in (Step 3), such as those in which the dielectric sheets are misaligned. The unfired waste before degreasing in production includes unused portions of the dielectric slurry prepared in (Step 1) and the conductive paste for the internal electrode layers. The unfired waste before degreasing in production is a dielectric sheet on which the patterns of the internal electrode layers prepared in (Step 1) and (Step 2) are not printed. It is preferable that the PET film is removed from the dielectric sheet. The unfired waste before degreasing in production includes unused portions of the metal powder, ceramic powder, rare earth powder, resin component, etc. contained in the dielectric slurry in (Step 1) and the conductive paste for the internal electrode layers, or a mixture of at least some of these.

[0040] (2) Flow of Separation and Recovery Method The flow of the separation and recovery method of this invention for unburned waste before burning and before production and degreasing will be described with reference to Figure 1A. The separation and recovery method of Figure 1A includes a common separation and recovery route, a rare earth component separation and recovery route, and a metal component separation and recovery route. The rare earth component separation and recovery route and the metal component separation and recovery route each branch off from the common separation and recovery route.

[0041] The common separation and recovery route includes, for example, the preparation of unburned waste before production degreasing in step (A), recycling degreasing in step (E), pulverization in step (B), and magnetic separation in step (C). After magnetic separation in step (C), the process branches into a separation and recovery route for rare earth components and a separation and recovery route for metal components. The separation and recovery route for rare earth components can include, for example, dissolution of rare earth powder-containing material in step (D), and further include filtration in step (F) and neutralization in step (G). Furthermore, the separation and recovery route for metal components can include, for example, electrolytic refining in step (H), and further include various treatments in step (I).

[0042] (Step (A): Preparation of unfired waste before manufacturing degreasing) In step (A), unfired waste before firing (firing of laminated chips) and before manufacturing degreasing, which is discharged in the manufacturing process of a multilayer ceramic capacitor, is prepared. The unfired waste before manufacturing degreasing is as described above. The unfired waste before manufacturing degreasing contains metal powder, ceramic powder, rare earth powder, and a resin component. The metal powder mainly constitutes the internal electrode layer 16_U when unfired. The ceramic powder mainly constitutes the ceramic layer 14_U when unfired.

[0043] Metal powders are, for example, aggregates of metal atoms. As mentioned above, metal powders can be composed of conductive materials containing magnetic metals, and the magnetic metals can be elemental metals or alloys. Examples of magnetic metals include Ni and Fe. While not limited to these, metal powders can be produced using predetermined raw materials by, for example, chemical vapor deposition (CVD), physical vapor deposition (PVD), atomization, chemical reduction, or other methods. Metal powders with desired particle sizes can be obtained by adjusting the production conditions in various metal powder production methods. Japanese Patent No. 4280184 also discloses a method for producing Ni as metal powder using a CVD method. According to this method, a metal chloride, such as nickel chloride, is heated and evaporated to generate a metal chloride gas, and then the metal chloride gas is brought into contact with a reducing gas to cause a gas-phase chemical reaction, thereby producing fine-particle nickel powder with an average particle size of approximately 5 μm.

[0044] Ceramic powder is an aggregate of dielectric materials. Examples of dielectric materials include, as mentioned above, BaTiO3, CaTiO3, SrTiO3, and CaZrO3. Ceramic powders can be produced by, but are not limited to, solid-phase methods, sol-gel methods, hydrothermal methods, and the like. Ceramic powders having desired particle sizes can be obtained by adjusting the production conditions in various ceramic powder production methods. Furthermore, according to Japanese Patent Laid-Open Publication No. 2023-146779, BaTiO3, an example of ceramic powder, can generally be synthesized by reacting a titanium raw material such as titanium dioxide with a barium raw material such as barium carbonate.

[0045] Rare earth powder is a collection of rare earth atoms. As mentioned above, the rare earth atoms can be at least one of Dy, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb, and Lu. Rare earth powders can be produced by, but are not limited to, spray pyrolysis, CVD, homogeneous precipitation, sol-gel, reverse micelle, and hydrothermal synthesis. Rare earth powders with desired particle sizes can be obtained by adjusting the production conditions in various rare earth powder production methods. Rare earth powders can also be produced by the rare earth production method disclosed in Japanese Patent No. 5,987,778.

[0046] The ceramic powder includes a first ceramic powder and a second ceramic powder. The second ceramic powder has a smaller particle size than the first ceramic powder. The first ceramic powder mainly constitutes the ceramic layer 14_U when unfired. Hereinafter, when simply referring to ceramic powder, it refers to at least one of the first ceramic powder and the second ceramic powder. The first ceramic powder may be, for example, a powder having a specific surface area of ​​1 m or less. 2 / g or more 10m 2 The second ceramic powder may be selected from those having a specific surface area of ​​10 m / g or less. 2 / g or more 100m 2 The metal powder may be selected from those having a specific surface area of ​​1 m 2 / g or more 10m 2 The second ceramic powder can be selected from those having a specific surface area of ​​0.1 / g or less. The second ceramic powder functions as a co-material for the metal powder, and therefore has a smaller particle size than the metal powder. Therefore, the second ceramic powder is selected so that the specific surface area is greater than that of the metal powder.

[0047] In the unfired waste before production and degreasing, the metal powder and the ceramic powder are at least partially adhered to each other. In this embodiment, in the unfired waste before production and degreasing, the metal powder, the first ceramic powder, the second ceramic powder, and the rare earth powder are at least partially adhered to each other. In this embodiment, mainly, the metal powder and the second ceramic powder are at least partially adhered to each other, and the rare earth powder and the first ceramic powder are at least partially adhered to each other.

[0048] The adhesion of the metal powder, ceramic powder, and rare earth powder can be exemplified by the following: For example, when the metal powder and the ceramic powder are at least partially adhered to each other, when the ceramic powder and the rare earth powder are at least partially adhered to each other, when the metal powder and the rare earth powder are at least partially adhered to each other, and when the metal powder, the ceramic powder, and the rare earth powder are at least partially adhered to each other. Here, "adhered" primarily means that the powders, such as the metal powder, the ceramic powder, and the rare earth powder, are not chemically bonded to each other. However, "adhered" may also mean that the powders, such as the metal powder, the ceramic powder, and the rare earth powder, are partially chemically bonded to each other. Note that the chemical bond is a bond in which multiple atoms are attracted to each other by positive and negative charges, such as an ionic bond, a covalent bond, or a metallic bond.

[0049] The reason why the powder particles in the unfired waste before production and degreasing are not basically chemically bonded to each other but are instead stuck together is because the unfired waste before production and degreasing is not degreased at the degreasing temperature in step 5 (higher than 800°C and lower than 1000°C), and the laminated chips are not fired (higher than 1000°C and lower than 1400°C) in step 6. In particular, powder particles can be chemically bonded to each other when fired at the firing temperature in step 6 (higher than 1000°C and lower than 1400°C), but the unfired waste before production and degreasing does not go through step 6, and so the powder particles are not basically chemically bonded to each other but are instead stuck together.

[0050] Furthermore, "at least partially adhered to each other" can be explained as follows, taking the example of adhesion between a metal powder and a ceramic powder. When a metal powder and a ceramic powder are at least partially adhered to each other, it is not necessary for all of the metal powder to be adhered to the ceramic powder, as long as at least a portion of the metal powder is adhered to the ceramic powder. It is also not necessary for all of the ceramic powder to be adhered to the metal powder, as long as at least a portion of the ceramic powder is adhered to the metal powder. The same can be said for other adhesions, such as between ceramic powder and rare earth powder.

[0051] As described above, the unburned waste before degreasing in this embodiment includes a metal powder, a ceramic powder, a rare earth powder, and a resin component. More specifically, the unburned waste before degreasing in this embodiment includes a metal powder-containing material and a rare earth powder-containing material. Here, the metal powder-containing material refers to a material containing a metal powder and a ceramic powder. Furthermore, the rare earth powder-containing material refers to a material containing a rare earth powder and a ceramic powder. In this embodiment, the metal powder-containing material refers to a material containing a metal powder and a second ceramic powder, and the metal powder and the second ceramic powder are at least partially adhered to each other. In this embodiment, the rare earth powder-containing material refers to a material containing a rare earth powder and a first ceramic powder, and the rare earth powder and the first ceramic powder are at least partially adhered to each other.

[0052] The resin components are binders and solvents used to produce conductive pastes for the dielectric sheets and internal electrode layers. The binders and solvents contain resin components, and various known thermosetting resins, such as epoxy resins, phenoxy resins, phenolic resins, urethane resins, and polyimide resins, can be used as the resin components. As mentioned above, inorganic elements such as Si are difficult to remove even by degreasing (including degreasing during manufacturing, recycling, and other processes). These inorganic elements remain in the unburned waste before degreasing as contaminants, adversely affecting the separation and recovery of rare earth and metal components. Therefore, resins that do not contain inorganic elements such as Si that are difficult to remove by degreasing (including degreasing during manufacturing, recycling, and other processes) are preferred.

[0053] The state of powder in laminated chips, which are unfired waste before manufacturing and degreasing, will be described using FIG. 5 . The unfired waste before manufacturing and degreasing shown in FIG. 5 is waste before undergoing manufacturing and degreasing (step 5) and firing of the laminated chips (step 6). The schematic diagram in FIG. 5 shows the state of various powders contained in this unfired waste before manufacturing and degreasing. Note that the resin component is not shown in FIG. 5 . As shown in FIG. 5 , in this embodiment, the unfired ceramic layer 14_U is primarily composed of a first ceramic powder (BT1 in FIG. 5 ). In addition, in the unfired ceramic layer 14_U, the first ceramic powder and the rare earth powder (Dy in FIG. 5 ) are at least partially adhered to each other. As shown in the example in FIG. 5 , the rare earth powder is primarily adhered to the surface of the first ceramic powder, and is not essentially chemically bonded to the first ceramic powder. In this embodiment, the unsintered internal electrode layer 16_U is mainly composed of metal powder (Ni in FIG. 5). In the unsintered internal electrode layer 16_U, the metal powder and the second ceramic powder (BT2 in FIG. 5) are at least partially adhered to each other. As shown in the example of FIG. 5, the second ceramic powder is mainly adhered to the surface of the metal powder, and the second ceramic powder is not basically infiltrated into the metal powder and chemically bonded thereto.

[0054] (Step (E): Recycle Degreasing) In step (E), resin components are removed from the unburned waste before production degreasing. Hereinafter, the removal of resin components here will be referred to as recycle degreasing. Recycle degreasing is performed, for example, by degreasing the unburned waste before production degreasing at a predetermined degreasing temperature. The degreasing temperature in recycle degreasing is, for example, a temperature just before chemical bonding begins in at least one of metal powder, ceramic powder, and rare earth powder contained in the unburned waste before production degreasing. Chemical bonding in firing the unburned waste before production degreasing includes, for example, chemical bonding between metal powder and ceramic powder, chemical bonding between ceramic powder and rare earth powder, chemical bonding between metal powder and rare earth powder, and chemical bonding between metal powder, ceramic powder, and rare earth powder. The degreasing temperature in recycle degreasing is preferably, for example, 600°C or higher and 1000°C or lower. The degreasing time in recycle degreasing is preferably continued until the resin components are completely removed. The degreasing time in the recycling degreasing depends on the amount of unburned waste before the manufacturing degreasing, the degreasing temperature, etc., but is, for example, from about 1 hour to about 24 hours. The recycling degreasing is preferably carried out in a reducing atmosphere such as a nitrogen atmosphere or an atmosphere containing hydrogen and water.

[0055] Unburned waste before degreasing contains resin components, which can hinder the separation of metal powder-containing materials and rare earth powder-containing materials during, for example, magnetic separation in step (C). Therefore, recycling degreasing is performed in step (E) to remove the resin components. Recycling degreasing is performed by degreasing the unburned waste before degreasing, for example, at a predetermined degreasing temperature. However, if the powders contained in the unburned waste before degreasing chemically bond with each other during this firing, it becomes difficult to separate the metal powder-containing materials and the rare earth powder-containing materials, which in turn makes it difficult to separate and recover the metal and rare earth components. Therefore, as described above, the degreasing temperature in recycling degreasing is set to a temperature just before chemical bonding begins between at least one of the metal powder, ceramic powder, and rare earth powder contained in the unburned waste before degreasing. This facilitates the separation of the metal powder-containing materials and the rare earth powder-containing materials. This in turn facilitates the separation and recovery of high-quality metal and rare earth components.

[0056] Furthermore, by setting the degreasing temperature in the recycling degreasing to 600°C or higher and 1000°C or lower as described above, chemical bonding can be suppressed in at least one of the metal powder, ceramic powder, and rare earth powder contained in the unburned waste before manufacturing degreasing. Therefore, metal components and rare earth components can be easily separated from the unburned waste before manufacturing degreasing. Note that the degreasing temperature in the recycling degreasing is set to 600°C or higher and 1000°C or lower in the above description. However, the lower limit of the degreasing temperature in the recycling degreasing can be set taking into account factors such as a temperature higher than the temperature at which the resin components in the unburned waste before manufacturing degreasing remain in an unburned state. Furthermore, the upper limit of the degreasing temperature in the recycling degreasing can be set taking into account factors such as the amount of electricity required to raise the temperature of the unburned waste before manufacturing degreasing to the upper limit of the degreasing temperature in the recycling degreasing, and the discharge standards for rivers for the solution containing the resin components remaining after recycling degreasing.

[0057] (Step (B): Refining) In step (B), the unburned waste before production degreasing is refined. For example, but not limited to, the unburned waste before production degreasing is refined by pulverizing. The pulverization is carried out by, but not limited to, a method of applying a pulverizing force by vibration to the object using a vibrating mill or the like, a method of grinding the object, a method of applying a pulverizing force by impact to the object, and the like. It is preferable to refine the unburned waste before production degreasing to approximately the particle size of each component, such as metal powder and ceramic powder, contained in the unburned waste before production degreasing, for example, to approximately the particle size of each component when used as raw materials for dielectric slurry and conductive paste for internal electrode layers. This makes it easier to separate and recover each component. The average particle size of the unburned waste before production degreasing after refinement is not limited. The average particle size can be determined, for example, using a sieve.

[0058] (Step (C): Magnetic Separation) In the magnetic separation of step (C), the unburned waste that has been pulverized in step (B) but has not yet been degreased is magnetically separated using a magnet. That is, the waste is separated into a material containing metal powder and a material containing rare earth powder, and then recovered.

[0059] The metal powder inclusion after magnetic separation mainly contains metal powder, such as Ni (Ni in the metal powder inclusion in FIG. 1A ), which is the main component of the internal electrode layer. Ceramic powder, such as BaTiO3, specifically the second ceramic powder (BT2 in the metal powder inclusion in FIG. 1A ), adheres to the surfaces of the metal powder in the metal powder inclusion. Here, the metal powder contains a magnetic metal. Meanwhile, the second ceramic powder is not magnetic. Through magnetic separation, the metal powder inclusion is separated as a magnetic substance. Specifically, in the metal powder inclusion, when the magnetic metal powder is separated as a magnetic substance, the non-magnetic second ceramic powder adheres to and becomes entangled with the metal powder. However, the second ceramic powder may not necessarily adhere to the surfaces of the metal powder in the metal powder inclusion, or other powders may adhere to the surfaces of the metal powder. Examples of other powders include the first ceramic powder, rare earth powder, and powders of additives other than ceramic and rare earth components (e.g., Mg, Mn, V).

[0060] This magnetic separation allows a metal powder-containing material to be separated and recovered as a metal component. For example, a metal powder-containing material containing a metal powder such as Ni with a second ceramic powder, BaTiO3, attached to its surface can be separated and recovered as a metal component. In the present invention, the separation and recovery of a metal component includes not only the separation and recovery of the metal component itself, but also the separation and recovery of a metal powder-containing material as a metal component.

[0061] The metal component includes metal atoms themselves, metal component compounds which are reaction products of metal atoms chemically reacting with other atoms, solutions of metal atoms, solutions of metal component compounds, etc. The state of the metal component may be any of a liquid state, a solid state, or a mixed state of liquid and solid. The metal component may also be any of an amorphous state, a crystalline state, or a mixed state of amorphous and crystalline.

[0062] Furthermore, the rare earth powder-containing material after magnetic separation primarily contains ceramic powder, such as BaTiO3, which is the main component of the unsintered ceramic layer, specifically the first ceramic powder (BT1 of the rare earth powder-containing material in FIG. 1A). Rare earth powder, such as Dy (Dy of the rare earth powder-containing material in FIG. 1A), adheres to the surface of the first ceramic powder in the rare earth powder-containing material. Here, the first ceramic powder and the rare earth powder are non-magnetic. Therefore, the first ceramic powder and the rare earth powder are separated as non-magnetic materials by magnetic separation. However, rare earth powder may not necessarily adhere to the surface of the first ceramic powder in the rare earth powder-containing material, or other powders may adhere to the surface of the first ceramic powder.

[0063] This magnetic separation allows the rare earth powder-containing material to be separated and recovered as rare earth components. For example, a rare earth powder-containing material mainly containing a first ceramic powder such as BaTiO3 with Dy rare earth powder attached to its surface can be separated and recovered as rare earth components. In the present invention, the separation and recovery of rare earth components includes not only the separation and recovery of the rare earth components themselves but also the separation and recovery of the rare earth powder-containing material as rare earth components.

[0064] The rare earth component includes rare earth atoms themselves, rare earth component compounds which are reaction products of rare earth atoms chemically reacting with other atoms, solutions of rare earth atoms, solutions of rare earth component compounds, etc. The rare earth component may be in a liquid state, a solid state, or a mixed state of liquid and solid. The rare earth component may be in an amorphous state, a crystalline state, or a mixed state of amorphous and crystalline.

[0065] In addition, during magnetic separation, it is preferable to mix and disperse the unburned waste before production degreasing after being pulverized in step (B) with water or an organic solvent, and then separate it using a magnet. Examples of organic solvents include alcohol-based organic solvents and hydrocarbon-based organic solvents. For example, methanol, ethanol, propanol, toluene, xylene, cyclohexane, or a mixture thereof can be used as the organic solvent.

[0066] When the unburned waste before degreasing and after pulverization is mixed with water or an organic solvent to form a mixed state, i.e., a slurry state, the metal powder-containing material and the rare earth powder-containing material contained in the unburned waste before degreasing and after pulverization can be dispersed. Therefore, in step (C), the metal powder-containing material and the rare earth powder-containing material can be easily separated using a magnet. When the unburned waste before degreasing and after pulverization is in a dry state, the metal powder-containing material and the rare earth powder-containing material tend to be less dispersed than in a slurry state. Therefore, for example, when the metal powder-containing material is attracted to a magnet, the rare earth powder-containing material is caught in the metal powder-containing material and attracted to the magnet, making it difficult to separate the metal powder-containing material and the rare earth powder-containing material.

[0067] (Step (D): Dissolution of rare earth powder-containing material) In step (D), the rare earth powder-containing material separated and recovered in step (C) is dissolved in a mineral acid. This causes the first ceramic powder contained in the rare earth powder-containing material to precipitate as an undissolved substance, and produces a rare earth component-containing solution in which the rare earth powder contained in the rare earth powder-containing material is dissolved as a rare earth component. The mineral acid is, for example, at least one selected from the group including sulfuric acid, nitric acid, and hydrochloric acid. In this case, the rare earth component is separated and recovered as a rare earth component-containing solution. In the present invention, separation and recovery of the rare earth component includes not only separating and recovering the rare earth component itself, but also separating and recovering the rare earth component from the rare earth component-containing solution as a rare earth component.

[0068] In step (D), it is preferable to adjust the pH of the rare earth component-containing solution to 1.5 or more and 2.5 or less by adding a mineral acid.

[0069] In step (D), the rare earth component-containing solution is adjusted to a pH of 1.5 or higher and 2.5 or lower using a mineral acid, thereby dissolving the rare earth powder in the mineral acid as a rare earth component. Furthermore, adjusting the pH to a stronger acid than the above range may result in the first ceramic powder and other components dissolving in the mineral acid. Therefore, it is preferable to adjust the pH to within the above range. More preferably, the rare earth component-containing solution is adjusted to a pH of 2 by adding a mineral acid.

[0070] In step (C), when the unburned waste before production and degreasing, which is in a slurry state, is subjected to magnetic separation, the separated rare earth powder-containing material is in a slurry state with a pH of about 7. By adding a mineral acid to this slurry, it is also possible to produce a rare earth component-containing solution with an adjusted pH of 1.5 or more and 2.5 or less. However, the rare earth powder-containing material after magnetic separation does not need to be in a slurry state and may be in a dry state.

[0071] When the first ceramic powder contained in the rare earth powder-containing material is, for example, BaTiO3, sulfuric acid is preferably used as the mineral acid. When sulfuric acid is used, insoluble BaSO4 is formed on the surface of the first ceramic powder (BaTiO3), thereby precipitating the first ceramic powder. On the other hand, the rare earth powder can be dissolved in sulfuric acid. Specifically, for example, by dissolving a rare earth powder-containing material mainly containing BaTiO3 with Dy attached to the surface in sulfuric acid, BaTiO3 is precipitated, and a dysprosium sulfate (Dy(SO4)3) solution in which Dy is dissolved in sulfuric acid is produced as a rare earth component-containing solution.

[0072] As mentioned above, the mineral acid may be other than sulfuric acid, such as hydrochloric acid. However, if hydrochloric acid is used as the mineral acid, soluble BaCl is formed on the surface of the first ceramic powder, BaTiO. Therefore, it is preferable to precisely adjust the pH of the hydrochloric acid so as to precipitate the first ceramic powder and dissolve the rare earth powder.

[0073] (Step (F): Filtration) In step (F), the rare earth component-containing solution containing the precipitated first ceramic powder produced in step (D) is filtered to separate the precipitated first ceramic powder and the rare earth component-containing solution into solid-liquid separation. This solid-liquid separation allows the rare earth component-containing solution, from which the precipitated first ceramic powder has been removed, to be separated and recovered as a rare earth component.

[0074] For example, suppose that BaTiO3 is precipitated in step (D) and a dysprosium sulfate (Dy(SO4)3) solution in which Dy is dissolved in sulfuric acid is produced as a rare earth component-containing solution. In this case, the dysprosium sulfate solution from which BaTiO3 has been removed can be separated and recovered as rare earth components by filtration in step (F).

[0075] The filtration can be performed using filter paper (filter cloth). The mesh size of the filter paper (filter cloth) is preferably such that the precipitated first ceramic powder does not pass through the filter paper (filter cloth).

[0076] The method for solid-liquid separation of the rare earth component-containing solution containing the precipitated first ceramic powder produced in step (D) is not limited to filtration, and can be selected appropriately from known methods such as decantation and centrifugation. Filtration is more preferred.

[0077] (Step (G): Neutralization) In step (G), the rare earth component-containing solution obtained in step (F) is neutralized to precipitate and recover the rare earth component. The precipitated rare earth component is separated and recovered, for example, by filtering the neutralized rare earth component-containing solution. At this time, the rare earth component is separated and recovered as a rare earth component compound (e.g., Dy(OH)3, etc.) by neutralization. In the present invention, separation and recovery of the rare earth component includes not only the separation and recovery of the rare earth component itself, but also the separation and recovery of a rare earth component compound, which is a reaction product of a chemical reaction of the rare earth component, as the rare earth component.

[0078] An alkali is used for neutralization. Examples of alkalis include sodium hydroxide and potassium hydroxide. Although the pH range in which rare earth components precipitate can change when the redox potential changes, using these alkalis can stabilize the pH range in which rare earth components precipitate.

[0079] In the neutralization step (G), the rare earth component is recovered by adjusting the pH of the rare earth component-containing solution to a value between 6 and 9. This allows the precipitate resulting from the neutralization reaction to be efficiently separated and recovered as the rare earth component. More preferably, the rare earth component-containing solution is adjusted to a pH of 8 by adding an alkali.

[0080] For example, when a dysprosium sulfate solution from which BaTiO3 has been removed is obtained in the filtration of step (F), dysprosium hydroxide (Dy(OH)3) is obtained as a rare earth component compound by neutralization with sodium hydroxide. That is, since the dysprosium sulfate solution is acidic, neutralization with an alkali allows the rare earth component dysprosium to precipitate as dysprosium hydroxide (Dy(OH)3), which can be separated and recovered. Here, dysprosium hydroxide (Dy(OH)3) can be separated and recovered by filtering the dysprosium sulfate solution neutralized with an alkali. In addition to filtration, known methods such as decantation and centrifugation can also be used.

[0081] Note that some metal components (so-called contaminants) are not separated as metal powder-containing materials in the magnetic separation of step (C) but are entrained in the rare earth powder-containing materials. Therefore, the rare earth component-containing solution produced by the dissolution of step (D) may contain metal components as contaminants. These metal components include, for example, Ti, Mn, and Ni. Then, in step (G), an alkali is added to the rare earth component-containing solution to adjust the pH to, for example, between 3 and 5, preferably about 4, thereby separating and recovering Ti, Mn, and the like. In this case, Ti precipitates as, for example, Ti(OH)4, and Mn precipitates as, for example, Mn(OH)2. Therefore, the rare earth component-containing solution adjusted to about pH 4 is filtered to recover Ti(OH)4, Mn(OH)2, and the like.

[0082] Thereafter, an alkali is further added to the solution containing the rare earth elements from which Ti, Mn, etc. have been separated, and the pH is adjusted to between 6 and 9, preferably about 8, as described above, to separate and recover the rare earth elements.

[0083] Thereafter, Ni and other components can be separated and recovered by adding an alkali to the solution from which Ti, Mn, rare earth components, etc. have been separated, and adjusting the pH to, for example, more than pH 9 but not more than pH 11, preferably about pH 10. In this case, Ni precipitates as, for example, Ni(OH)2. The solution adjusted to about pH 10 is filtered to recover Ni(OH)2 and other components.

[0084] By repeating stepwise neutralization and filtration in this manner, various components (contaminants, rare earth components, etc.) contained in the rare earth component-containing solution can be separated and recovered.

[0085] Furthermore, in the stepwise neutralization of the rare earth component-containing solution as described above, the rare earth component-containing solution is neutralized to a pH of 3 or more and 5 or less, preferably about pH 4, before separating the rare earth component. This allows contaminants such as Ti and Mn to be first removed from the rare earth component-containing solution. Since contaminants such as Ti and Mn have been removed from the rare earth component-containing solution in this manner, it is possible to further facilitate separation of the rare earth component using the rare earth component-containing solution in a state in which these contaminants have been removed.

[0086] (Step (H): Electrolytic Refining) In step (H), the metal powder-containing material separated and recovered in step (C) is introduced into an electrolytic solution 61a ( FIG. 1B ), and metal components constituting the metal powder are recovered from the metal powder-containing material by electrolytic refining. For example, electrolytic refining is performed using an electrolytic refining system 60 shown in FIG. 1B . FIG. 1B is a configuration diagram of the electrolytic refining system. The electrolytic refining system 60 includes an electrolytic cell 61, an anode 62, a cathode 63, a power supply 64, and an anode basket 65. The electrolytic cell 61 is filled with an electrolytic solution 61a, and the anode 62 and cathode 63 are attached to the electrolytic cell 61 so as to be immersed in the electrolytic solution 61a. The anode basket 65 can accommodate the metal powder-containing material, which is the treatment target 65a, and is formed integrally with the anode 62. The anode basket 65 is immersed in the electrolytic solution 61a and is configured to be permeable to ions of the metal components in the metal powder-containing material. The power supply 64 applies electricity between the anode 62 and the cathode 63.

[0087] By applying a predetermined voltage to the power supply 64, the metal components in the metal powder-containing material housed in the anode basket 65 are ionized. The metal components ionized at the anode 62 reach the cathode 63. The ions of the metal components are precipitated on the surface of the cathode 63. This allows the metal components in the metal powder-containing material to be separated and recovered by electrolytic refining. Note that the components other than the metal components in the metal powder-containing material, mainly the ceramic powder, are precipitated.

[0088] For example, if the metal component in the metal powder is Ni (Ni in FIG. 1B), the anode 62 will have Ni+2e - →Ni 2+ On the other hand, at the cathode 63, the reaction 2+ +2e - → A reaction of Ni occurs, and Ni is precipitated on the surface of the cathode 63, whereby it can be separated and recovered. Note that the ceramic powder (BT2 in FIG. 1B) other than the metal component in the metal powder-containing material is mainly precipitated.

[0089] When recovering metal components from a metal powder-containing material using this electrolytic refining method, almost no hydrogen is generated when the metal components in the metal powder-containing material are ionized. Therefore, electrolytic refining can prevent explosions caused by hydrogen combining with oxygen, allowing for safe separation and recovery. Furthermore, electrolytic refining can deposit the target metal components on an electrode, allowing for recovery of relatively high-purity metal components.

[0090] Note that, as long as electrolytic refining is possible by passing a current through the metal powder-containing material, which is the treatment target 65a, the viewpoint of the innovation may be the electrolytic refining system 60 or the metal powder-containing material, which is the treatment target 65a. When the electrolytic refining system 60 is improved, it is conceivable to combine magnets with electrodes so that the metal powder adheres closely to the electrodes during current flow. In this case, it is not necessary to process the metal powder-containing material, which is the treatment target 65a, into a mass as described below.

[0091] In this embodiment, the metal powder-containing material, which is the processing target 65a, contains a metal powder and a second ceramic powder. If the metal powder is dispersed in the metal powder-containing material, even when a voltage is applied from the anode 62, it is difficult for current to flow through the entire metal powder in the anode basket 65, making it difficult to ionize the entire metal powder. As described above, by processing the metal powder-containing material into clumps in which the metal powder particles are in contact with each other to the extent that current can flow, the degree of contact between the metal powder particles in the metal powder-containing material can be increased. Therefore, it is easier to pass current through the entire metal powder in the anode basket 65 and ionize the entire metal powder. Forming clumps so that the proportion of metal powder in the metal powder-containing material is 60 wt % or more, more preferably 80 wt % or more, and even more preferably 90 wt % or more makes it easier to pass current through the entire metal powder, and is therefore preferable.

[0092] When devising the metal powder-containing material to be treated 65a, it is possible to process it into a lump in which the metal powder is in contact with the material to the extent that an electric current can flow. Examples of methods for processing the metal powder-containing material into a lump include compressing the metal powder-containing material to form a tight bond, heat-treating the metal powder-containing material by partially melting the metal powder with heat to form a tight bond, and combinations of these. The temperature for the heat treatment is, for example, 600°C or higher, preferably 800°C or higher, and more preferably 1200°C or higher. It is preferable to compress the metal powder to a degree that causes plastic deformation. In other words, it is preferable to compress the metal powder to a level equal to or higher than the yield stress of the metal powder. Furthermore, a binder may be added to the metal powder-containing material when processing it into a lump. The binder is not limited as long as it can form the metal powder-containing material into a lump, and examples thereof include PVA. Using a binder with good thermal decomposition properties is preferable from an environmental perspective, as it is less likely to be burned during heat treatment and leached into wastewater.

[0093] In the above example, the metal powder-containing material accommodated in the anode basket 65 is electrolytically refined to deposit the metal component on the surface of the cathode 63. However, depending on the type of metal component, the metal component may be deposited on the surface of the anode 62 by, for example, electrolytically refining the metal powder-containing material accommodated in a cathode basket (not shown).

[0094] (Step (I): Various Treatments) In step (I), the metal components recovered in step (H) can be recovered by treating them. For example, the metal components recovered in step (H) are reacted with a solution to produce a metal component-containing solution, and the metal components are separated and recovered as desired metal component compounds. For example, if the metal component is Ni, the metal component can be separated and recovered as metal component compounds such as NiSO4 and NiCl2 by reacting it with sulfuric acid, hydrochloric acid, or the like. In the present invention, separation and recovery of metal components includes not only the separation and recovery of the metal components themselves, but also the separation and recovery of metal component compounds, which are the reaction products of the metal components chemically reacted, as the metal components.

[0095] (3) Effects According to the above separation and recovery method, not only the metal components constituting the internal electrode layers but also the rare earth components added to the ceramic powder constituting the ceramic layers can be separated and recovered from the unfired waste before production and degreasing. The details will be explained below.

[0096] First, the present inventors have newly focused on separating and recovering metal components and rare earth components from unfired waste before firing (firing of laminated chips) and before degreasing, which is discharged during the manufacturing process of multilayer ceramic capacitors. Specifically, the inventors have newly focused on the fact that in unfired waste before firing (firing of laminated chips) and before degreasing, the materials constituting the unfired waste before degreasing, such as metal powder, ceramic powder (first and second ceramic powders), and rare earth powder, are generally not chemically bonded together by sintering, and at least some of the powders of each material remain adhered to each other. Therefore, the unfired waste before degreasing can be easily separated into individual materials by a pulverization process (B) or other such process. Furthermore, because the metal components and rare earth components in the unfired waste before degreasing are materials used in the manufacture of multilayer ceramic capacitors, the purity of the metal components and rare earth components is higher than that of naturally occurring ores. Therefore, by carrying out the above separation and recovery method starting from unburned waste before production and degreasing, it is possible to separate and recover high-purity metal components and high-purity rare earth components.

[0097] Furthermore, the unfired waste before production and degreasing after being pulverized can be separated into a metal powder-containing material and a rare earth powder-containing material by using a magnet in step (C). Then, in step (D), the rare earth powder-containing material is dissolved in a mineral acid to produce a rare earth component-containing solution in which the rare earth powder contained in the rare earth powder-containing material is dissolved as a rare earth component. In step (D), the first ceramic powder contained in the rare earth powder-containing material reacts with the mineral acid and precipitates as an undissolved substance, so the first ceramic powder and the rare earth powder contained in the rare earth powder-containing material are separated. Furthermore, since the unfired waste before production and degreasing has not been fired (fired into a laminated chip), in the rare earth powder-containing material, for example, the rare earth powder is attached to the surface of the first ceramic powder, and the first ceramic powder and the rare earth powder are not sintered. Therefore, the first ceramic powder and the rare earth powder are easily separated by the dissolution in step (D).

[0098] By passing through the separation and recovery method including the steps (C) and (D), rare earth components can be separated and recovered as a rare earth component-containing solution from the unburned waste after pulverization but before production and degreasing. Furthermore, the proportion of rare earth components in the material containing rare earth components increases as each step passes. Therefore, rare earth components such as Dy can be recovered at high quality.

[0099] Furthermore, by treating the metal powder-containing material by electrolytic refining in step (H), the metal components in the metal powder-containing material can be recovered. Furthermore, by using electrolytic refining, almost no hydrogen is generated when the metal components in the metal powder-containing material are ionized, and the metal components can be recovered safely. Furthermore, by using electrolytic refining, the metal components can be recovered with a relatively high purity.

[0100] By going through the separation and recovery method including these steps (C) and (H), it is possible to separate and recover metal components from the unburned waste after pulverization but before production degreasing. Furthermore, the proportion of metal components in the material containing metal components increases as each step goes through. Therefore, it is possible to recover metal components such as Ni at high quality.

[0101] As described above, the unfired waste before degreasing that is discharged in the manufacturing process of a multilayer ceramic capacitor is used to separate and recover metal components, rare earth components, etc., so instead of discarding the unfired waste before degreasing as waste, it can be used as a resource and the environmental load can be reduced.

[0102] 1.2 Experimental Example Hereinafter, an experimental example will be described in which metal components and rare earth components were recovered from unburned waste before production and degreasing.

[0103] [Example] 10 g of unburned waste before degreasing was prepared. The 10 g of unburned waste before degreasing contained 34% by mass (3.4 g) of Ni, a metal powder, 52% by mass (5.2 g) of BaTiO3, a ceramic powder, 2% by mass (0.2 g) of Dy, a rare earth powder, 10% by mass (1.0 g) of resin components, and 2% by mass (0.2 g) of contaminants such as Mg, Mn, and SiO2 (step (A)). This unburned waste before degreasing was fired at a degreasing temperature of 800°C for 2 hours for recycling (step (E)). The unburned waste after recycling degreasing and before degreasing was pulverized and finely divided (step (B)). The pulverized unburned waste before degreasing was mixed with 100 ml of water to prepare a slurry. This slurry was magnetically separated using a magnet. Through this magnetic separation, 3.4 g of metal powder-containing material, primarily consisting of Ni with BaTiO3 attached, was separated and recovered, and 5.0 g of rare earth powder-containing material, primarily consisting of BaTiO3 with Dy attached, was separated and recovered (step (C)). Subsequently, 100 ml of water was added to the 5.0 g of rare earth powder-containing material, and 1 mol% sulfuric acid was gradually added to adjust the pH to 2. This caused the BaTiO3 in the rare earth powder-containing material to precipitate, and the Dy to dissolve in the sulfuric acid solution (step (D)). The solution containing the precipitated BaTiO3 and the dissolved Dy was filtered to obtain 90 ml of dysprosium sulfate (Dy(SO4)3) solution (step (F)). A 1 mol% caustic soda solution was gradually added to the 90 ml of dysprosium sulfate solution as an alkali, adjusting the pH to 8 (step (G)). This solution was filtered to separate and recover 0.2 g of Dy(OH)3. Thus, by going through this process, approximately 60% of the Dy contained in the unburned waste before degreasing was recovered.

[0104] In addition, 3.4 g of the metal powder-containing material recovered in step (C), mainly consisting of Ni with BaTiO3 attached, was heat-treated to obtain a metal lump. This metal lump was placed in an anode basket 65, an anode was installed as the counter electrode, and electrolytic refining was performed by passing electricity necessary to deposit 1.0 g of nickel metal on the cathode (step (H)). The nickel metal deposited on the anode was peeled off, and 0.9 g of metallic nickel was separated and recovered. 0.9 g of the metallic nickel solution was dissolved in 9 ml of sulfuric acid to obtain a nickel sulfate solution (step (I)).

[0105] 1A , high-quality rare earth components and metal components such as Dy and Ni can be easily separated and refined by using unburned waste before degreasing that is discharged in the manufacturing process of a multilayer ceramic capacitor as a starting material and then going through processes such as magnetic separation and electrolytic refining. In other words, by using unburned waste before degreasing as a starting point, high-quality metals such as Dy and Ni can be separated and refined by a simpler process than when refining Dy and Ni from ore.

[0106] 1.3 Modifications Modifications of the separation and recovery method of FIG. 1A for unburned waste before burning and before production and degreasing will be described below.

[0107] (1) Generation of Slurry in Step (B) (1-1) Generation of Slurry Using an Organic Solvent In the above-described embodiment, the unburned waste before production degreasing is pulverized and refined in step (B). However, as long as the unburned waste before production degreasing can be refined, the unburned waste before production degreasing may be refined by, for example, dispersing the unburned waste in an organic solvent to form a slurry, in addition to or instead of the refinement in step (B) (particularly, refinement by pulverization). Here, the refinement in which the unburned waste before production degreasing is mixed with a solvent (such as an organic solvent or an aqueous solvent) to form a slurry is referred to as wet refinement. Furthermore, among the wet refinement methods, the refinement in which the unburned waste before production degreasing is pulverized in a slurry formed by mixing the unburned waste before production degreasing with a solvent is referred to as wet grinding.

[0108] In this case, the separation and recovery method includes, as a common separation and recovery route, the preparation of unburned waste before production and degreasing in step (A), recycling degreasing in step (E), mixing of the unburned waste before production and degreasing with an organic solvent (carried out together with the pulverization (particularly pulverization by grinding) in step (B) or instead of the pulverization (particularly pulverization by grinding) in step (B)), and magnetic separation in step (C), in this order. When the unburned waste before production and degreasing is mixed with an organic solvent in this way, it is preferable to further include a distillation step for removing the organic solvent after the magnetic separation in step (C).

[0109] The separation and recovery method further includes dissolution of a rare earth powder-containing material in step (D) as a route for separating and recovering rare earth components, following the common separation and recovery route. The rare earth component separation and recovery route may additionally include filtration in step (F) and neutralization in step (G). The separation and recovery method further includes electrolytic refining in step (H) as a route for separating and recovering metal components, following the common separation and recovery route. The metal component separation and recovery route may additionally include various treatments in step (I).

[0110] That is, the separation and recovery method preferably includes, as a common separation and recovery route, the steps of preparing unburned waste before production and degreasing in step (A), recycling degreasing in step (E), mixing the unburned waste before production and degreasing with an organic solvent to produce a slurry, pulverizing in step (B) (particularly, pulverizing by grinding), and magnetic separation in step (C), in this order, and further includes a step of distilling off the organic solvent after the magnetic separation in step (C). By changing the order of this common separation and recovery route, the steps of preparing unburned waste before production and degreasing in step (A), recycling degreasing in step (E), pulverizing in step (B) (particularly, pulverizing by grinding), mixing the unburned waste before production and degreasing that has been pulverized with an organic solvent to produce a slurry, and magnetic separation in step (C), are preferably performed in this order, and further includes a step of distilling off the organic solvent after the magnetic separation in step (C). Alternatively, the common separation and recovery route may omit the pulverization (particularly pulverization by grinding) of step (B), and may include, for example, the preparation of unburned waste before production and degreasing in step (A), recycling degreasing in step (E), production of a slurry by mixing the unburned waste before production and degreasing with an organic solvent, and magnetic separation in step (C) in this order, and may further include a distillation step for removing the organic solvent after the magnetic separation in step (C).

[0111] Examples of the organic solvent include alcohol-based organic solvents and hydrocarbon-based organic solvents, such as methanol, ethanol, propanol, toluene, xylene, cyclohexane, and mixtures thereof.

[0112] In the above embodiment, the resin components in the unburned waste before manufacturing degreasing are removed in the recycling degreasing in step (E). However, as described above, when the unburned waste before manufacturing degreasing is made into a slurry state using an organic solvent, the resin components in the unburned waste before manufacturing degreasing may dissolve in the organic solvent. In other words, by mixing and dispersing the unburned waste before manufacturing degreasing in an organic solvent, the resin components in the unburned waste before manufacturing degreasing can be removed, and therefore the recycling degreasing in step (E) can be omitted.

[0113] It is also possible to pulverize the unburned waste before production and degreasing by mixing the unburned waste before production and degreasing with an organic solvent. In this case, the unburned waste before production and degreasing can be pulverized in some cases without pulverization in step (B).

[0114] For these reasons, the separation and recovery method includes, as a common separation and recovery route, step (A) of preparing unburned waste before production and degreasing, mixing the unburned waste before production and degreasing with an organic solvent (performed in conjunction with or instead of the pulverization (particularly pulverization by grinding) in step (B)), and step (C) of magnetic separation. Note that, since the unburned waste before production and degreasing is mixed with an organic solvent, it is preferable to further include a distillation step for removing the organic solvent after the magnetic separation in step (C). Furthermore, the separation and recovery method includes, following the common separation and recovery route, dissolution of the rare earth powder-containing material in step (D) as a separation and recovery route for the rare earth component. Note that, in the separation and recovery route for the rare earth component, filtration in step (F) and neutralization in step (G) may additionally be performed. Furthermore, the separation and recovery method includes, following the common separation and recovery route, electrolytic refining in step (H) as a separation and recovery route for the metal component. In addition, various treatments in step (I) may be carried out as an additional route for separating and recovering metal components.

[0115] That is, the separation and recovery method preferably includes, as a common separation and recovery route, the steps of preparing unburned waste before production and degreasing in step (A), mixing the unburned waste before production and degreasing with an organic solvent to produce a recycled and degreasing slurry, pulverizing (particularly, pulverizing by grinding) in step (B), and magnetic separation in step (C), in this order, and further includes a step of distilling off the organic solvent after the magnetic separation in step (C). By changing the order of this common separation and recovery route, the separation and recovery method preferably includes the steps of preparing unburned waste before production and degreasing in step (A), pulverizing (particularly, pulverizing by grinding) in step (B), mixing the unburned waste before production and degreasing, pulverized by grinding, with an organic solvent to produce a recycled and degreasing slurry, and magnetic separation in step (C), in this order, and further includes a step of distilling off the organic solvent after the magnetic separation in step (C). Alternatively, a common separation and recovery route may omit the pulverization (particularly pulverization by grinding) of step (B), and may include, for example, the steps of preparing unburned waste before production and degreasing in step (A), mixing the unburned waste before production and degreasing with an organic solvent to produce a recycled and degreased slurry, and magnetic separation in step (C), in this order, and may further include a distillation step for removing the organic solvent after the magnetic separation in step (C).

[0116] Furthermore, in the above embodiment, during the magnetic separation in step (C), the unburned waste before production degreasing, which has been pulverized in step (B), is mixed with water or an organic solvent and dispersed to form a slurry. However, as described above, when the unburned waste before production degreasing is pulverized using an organic solvent in addition to or instead of pulverization in step (B), this slurried unburned waste before production degreasing may be magnetically separated in step (C). In other words, the effort of generating a slurry in the magnetic separation in step (C) can be omitted.

[0117] (1-2) Generation of Slurry Using an Aqueous Solvent Although the slurry is generated using an organic solvent in the above example, the slurry may also be generated using an aqueous solvent. In this case, the separation and recovery method includes, as a common separation and recovery route, the preparation of unburned waste before production and degreasing in step (A), recycling degreasing in step (E), mixing of the unburned waste before production and degreasing with an aqueous solvent (performed in conjunction with or instead of the pulverization (particularly pulverization) in step (B)), and magnetic separation in step (C), in this order. The separation and recovery method also includes, following the common separation and recovery route, dissolution of a rare earth powder-containing material in step (D) as a separation and recovery route for a rare earth component. The separation and recovery route for a rare earth component may additionally include filtration in step (F) and neutralization in step (G). The separation and recovery method also includes electrolytic refining in step (H) as a separation and recovery route for a metal component, following the common separation and recovery route. In addition, various treatments in step (I) may be carried out as an additional route for separating and recovering metal components.

[0118] That is, the separation and recovery method includes, as a common separation and recovery route, for example, the preparation of unburned waste before production and degreasing in step (A), recycling degreasing in step (E), production of a slurry by mixing the unburned waste before production and degreasing with an aqueous solvent, pulverization (particularly, pulverization by grinding) in step (B), and magnetic separation in step (C), in this order. By changing the order of this common separation and recovery route, the preparation of unburned waste before production and degreasing in step (A), recycling degreasing in step (E), pulverization (particularly, pulverization by grinding) in step (B), production of a slurry by mixing the unburned waste before production and degreasing that has been pulverized by grinding with an aqueous solvent, and magnetic separation in step (C) can also be carried out in this order. Alternatively, a common separation and recovery route can omit the pulverization (particularly pulverization by grinding) of step (B), and include, for example, the following steps in this order: preparation of unburned waste before production degreasing in step (A), recycling degreasing in step (E), generation of a slurry by mixing the unburned waste before production degreasing with an aqueous solvent, and magnetic separation in step (C). Note that water, for example, can be used as the aqueous solvent.

[0119] Furthermore, in the first embodiment described above, during the magnetic separation in step (C), the unburned waste before production degreasing, which has been pulverized in step (B), is mixed with and dispersed in water or an organic solvent to form a slurry. However, as described above, when the unburned waste before production degreasing is made into a slurry state using an aqueous solvent in addition to or instead of the pulverization in step (B), the unburned waste before production degreasing in this slurry state may be magnetically separated in step (C). In other words, the effort of generating a slurry state in the magnetic separation in step (C) can be omitted.

[0120] (2) Micronization in step (B) Micronization in step (B) may be dry micronization, which is micronization of the target material, such as unburned waste before production degreasing, in a dry state. Dry micronization differs from wet micronization, which mixes the target material with a solvent (such as an organic solvent or an aqueous solvent) to form a slurry. Among dry micronization, grinding the target material in a dry state is sometimes called dry grinding.

[0121] (3) Location of the recycle degreasing in step (E) in the separation and recovery method In the above embodiment, in the separation and recovery method shown in Fig. 1A, the recycle degreasing in step (E) is performed between steps (A) and (B). That is, in Fig. 1A, the unburned waste before production degreasing prepared in step (A) is recycled and degreased (step (E)), and then the unburned waste before production degreasing (recycled and degreased unburned waste before production degreasing) is pulverized in step (B). However, the recycle degreasing in step (E) only needs to be performed before the rare earth powder-containing material and metal powder-containing material separated by magnetic separation in step (C) are input into steps (D) and (H), and is not limited to being performed between steps (A) and (B).

[0122] For example, the recycle degreasing in step (E) may be performed between steps (B) and (C). That is, the unburned waste before production degreasing, which is prepared in step (A), can be pulverized in step (B) and then recycled and degreased. In this case, a common separation and recovery route among the separation and recovery methods includes, in this order, the preparation of the unburned waste before production degreasing in step (A), the pulverization in step (B), the recycle degreasing in step (E), and the magnetic separation in step (C).

[0123] Furthermore, for example, the recycling degreasing in step (E) may be performed between step (C), step (D), and step (H). Thus, after magnetic separation in step (C), the rare earth powder-containing material can be recycled and degreased before step (D). Furthermore, the metal powder-containing material can be recycled and degreased before step (H). In this case, a common separation and recovery route among the separation and recovery methods includes, in this order, the preparation of unburned waste before production and degreasing in step (A), the pulverization in step (B), the magnetic separation in step (C), and the recycling and degreasing in step (E). Furthermore, in the recycling and degreasing in step (E), the rare earth powder-containing material recovered by magnetic separation in step (C) is recycled and degreased, while the metal powder-containing material recovered by magnetic separation in step (C) is recycled and degreased.

[0124] Furthermore, the recycling degreasing in step (E) may be carried out during the pulverization in step (B). That is, during the pulverization process in step (B), the resin component can be recycled and degreased from the unburned waste before the manufacturing degreasing. For example, in step (B), the unburned waste before the manufacturing degreasing can be mixed with an organic solvent to be recycled, degreased, and pulverized. In this case, a common separation and recovery route among the separation and recovery methods includes, in this order, the preparation of the unburned waste before the manufacturing degreasing in step (A), the pulverization by mixing with an organic solvent in step (B), and the magnetic separation in step (C).

[0125] (4) Another embodiment of manufacturing and degreasing In the separation and recovery method shown in FIG. 1A, manufacturing and degreasing are performed in step 5, and the laminated chips are fired in step 6. However, both steps 5 and 6 may be combined into one step. For example, by firing the laminated chips after step 4 at a temperature higher than 1000°C and lower than 1400°C, the resin components in the laminated chips are manufactured and degreased, and the laminated chips are fired and sintered. In this case, the unfired waste before manufacturing and degreasing is waste before the process including both steps 5 and 6.

[0126] (5) Unfired Waste Before Degreasing: In the above-described embodiment, the manufacturing method for the multilayer ceramic capacitor 10 includes the steps of forming a laminate block (step 3), cutting into laminate chips (step 4), degreasing (step 5), firing the laminate chips (step 6), and applying and firing a base electrode layer paste (step 7). However, the manufacturing method for the multilayer ceramic capacitor 10 is not limited to this. For example, the manufacturing method may involve applying a base electrode layer paste to an unfired laminate chip before degreasing (step 5) and before firing (firing the laminate chips) (step 6), followed by degreasing and firing. That is, first, a base electrode layer paste containing Ni, glass components, resin components, etc. is applied to the laminate chip before degreasing (step 5). Next, the laminate chip coated with the base electrode layer paste is degreased and then fired. The temperature during degreasing is preferably, for example, higher than 800°C and lower than 1000°C. The firing temperature is preferably, for example, higher than 1000°C and not higher than 1400°C. These steps are performed after cutting into laminated chips in step 4 of the above-mentioned manufacturing method and before the plating step in step 8. In these steps, the firing of the laminated chips in step 6 and the firing of the base electrode layer paste in step 7 are performed in a single firing. Considering this manufacturing method, the unfired waste before manufacturing degreasing includes, in addition to those listed in the above embodiment, waste of laminated chips before manufacturing degreasing (before manufacturing degreasing in step 5), which is unfired after the base electrode layer paste has been applied (before the firing in step 6 and step 7 is performed simultaneously). In this case, Ni powder in the base electrode layer paste is included in the separation and recovery target. The base electrode layer paste may further contain a co-material made of ceramic powder.

[0127] 2. Unfired Waste Before Firing of Multilayer Chips and After Manufacturing Degreasing 2.1. Separation and Recovery Method for Unfired Waste Before Firing of Multilayer Chips and After Manufacturing Degreasing This section describes a separation and recovery method for separating and recovering rare earth components and metal components from unfired waste after manufacturing degreasing that is discharged during the manufacturing process of a multilayer ceramic capacitor and that is degreased before firing (firing of the multilayer chips) during the manufacturing process, according to an embodiment of the present invention. The separation and recovery method for unfired waste before firing and after manufacturing degreasing has a different treatment target than the separation and recovery method for unfired waste before firing and before manufacturing degreasing. In other words, the treatment target of the former separation and recovery method is unfired waste before manufacturing degreasing, while the treatment target of the latter separation and recovery method is unfired waste after manufacturing degreasing. Descriptions similar to those of the separation and recovery method for unfired waste before firing and before manufacturing degreasing will be simplified or omitted.

[0128] 6 is a flow chart showing a separation and recovery method according to an embodiment of the present invention for separating and recovering rare earth components and metal components from unfired waste after degreasing that is discharged in the manufacturing process of a multilayer ceramic capacitor and that is degreased in the manufacturing process and before firing (firing of laminated chips). In this separation and recovery method, the unfired waste after degreasing that is discharged in the manufacturing process of a multilayer ceramic capacitor and that is degreased in the manufacturing process and before firing (firing of laminated chips) is used as the starting point for separation and recovery. The unfired waste after degreasing will now be described.

[0129] (1) Unfired waste after manufacturing degreasing The structure and manufacturing method of the multilayer ceramic capacitor 10 are the same as those described in the separation and recovery method for unfired waste before firing and before manufacturing degreasing. Here, the unfired waste after manufacturing degreasing is waste after manufacturing degreasing in the manufacturing process (step 5) of the multilayer ceramic capacitor 10 manufacturing method, and is waste before firing of the laminated chips in (step 6). For example, the unfired waste after manufacturing degreasing is defective laminated chips in which the lamination of each dielectric sheet is misaligned after manufacturing degreasing in (step 5), or unnecessary excess laminated chips.

[0130] (2) Flow of Separation and Recovery Method The flow of the separation and recovery method for unburned waste before calcination and after production and degreasing of this invention will be described with reference to Figure 6. Unlike the separation and recovery method for unburned waste before calcination and before production and degreasing (Figure 1A), the separation and recovery method for unburned waste before calcination and after production and degreasing (Figure 6) omits the recycle degreasing step (E). This is because the separation and recovery method of Figure 6 targets unburned waste after production and degreasing that has undergone production and degreasing (step 5). Other points in the separation and recovery method of Figure 6 are generally the same as those in the separation and recovery method for unburned waste before calcination and before production and degreasing of Figure 1A, but will be briefly described below.

[0131] The separation and recovery method of Fig. 6 includes a common separation and recovery route, a rare earth component separation and recovery route, and a metal component separation and recovery route. The rare earth component separation and recovery route and the metal component separation and recovery route each branch off from the common separation and recovery route.

[0132] The common separation and recovery route includes, for example, the preparation of unburned waste after manufacturing and degreasing in step (A), pulverization in step (B), and magnetic separation in step (C). After magnetic separation in step (C), the process branches into a separation and recovery route for rare earth components and a separation and recovery route for metal components. The separation and recovery route for rare earth components can include, for example, dissolution of a rare earth powder-containing material in step (D), and further include filtration in step (F) and neutralization in step (G). Furthermore, the separation and recovery route for metal components can include, for example, electrolytic refining in step (H), and further include various treatments in step (I).

[0133] (Step (A): Preparation of Unfired Waste After Manufacturing Degreasing) In step (A), unfired waste after manufacturing degreasing, which is discharged in the manufacturing process of a multilayer ceramic capacitor, is prepared. The unfired waste after manufacturing degreasing includes metal powder, ceramic powder (first ceramic powder, second ceramic powder), and rare earth powder. The metal powder, ceramic powder, and rare earth powder are each as described above in the unfired waste before manufacturing degreasing. Unlike the unfired waste before manufacturing degreasing, the unfired waste after manufacturing degreasing is waste after the laminated chips have been manufactured and degreased in step 5, and therefore the resin components have been largely or completely degreased (removed). The resin components contained in the laminated chips, etc. before manufacturing degreasing are the same as those in the unfired waste before manufacturing degreasing.

[0134] In the unburned waste after manufacturing and degreasing, the metal powder, ceramic powder, and rare earth powder are at least partially adhered to one another, similar to the unburned waste before manufacturing and degreasing described above. In the unburned waste after manufacturing and degreasing, the resin component is not involved in the adhesion between the metal powder, ceramic powder, and rare earth powder. However, the adhesion between the metal powder, ceramic powder, and rare earth powder in the unburned waste after manufacturing and degreasing is generally the same as the adhesion between the metal powder, ceramic powder, and rare earth powder in the unburned waste before manufacturing and degreasing.

[0135] In the unburned waste after manufacturing and degreasing, the powder particles are in a state of adhering to each other and are not basically chemically bonded to each other because, although the unburned waste after manufacturing and degreasing is degreased at the degreasing temperature in step 5 (higher than 800°C and lower than 1000°C), the firing at the degreasing temperature in step 5 is not at a temperature that would allow chemical bonding between the powder particles. Furthermore, although firing at the firing temperature in step 6 (higher than 1000°C and lower than 1400°C) would allow chemical bonding between the powder particles, the unburned waste after manufacturing and degreasing has not been subjected to step 6, and therefore the powder particles are basically not chemically bonded to each other but are in a state of adhering to each other.

[0136] As described above, the unfired waste after manufacturing and degreasing in this embodiment contains a metal powder, a ceramic powder, and a rare earth powder. More specifically, the unfired waste after manufacturing and degreasing in this embodiment contains a metal powder-containing material and a rare earth powder-containing material. The configurations of the metal powder-containing material and the rare earth powder-containing material are the same as those of the unfired waste before manufacturing and degreasing described above. In other words, the metal powder-containing material refers to a material containing a metal powder and a ceramic powder. Furthermore, the rare earth powder-containing material refers to a material containing a rare earth powder and a ceramic powder. In this embodiment, the metal powder-containing material refers to a material containing a metal powder and a second ceramic powder, and the metal powder and the second ceramic powder are at least partially adhered to each other. In this embodiment, the rare earth powder-containing material refers to a material containing a rare earth powder and a first ceramic powder, and the rare earth powder and the first ceramic powder are at least partially adhered to each other. The state of the powder of unburned waste after such manufacturing and degreasing is generally similar to the state of the powder of unburned waste before manufacturing and degreasing described in FIG. 5 of the first embodiment, except that it does not contain any resin components.

[0137] The separation and recovery method for unburned waste before manufacturing and degreasing and the separation and recovery method for unburned waste after manufacturing and degreasing differ in that the object of treatment is either unburned waste before manufacturing and degreasing or unburned waste after manufacturing and degreasing. Broadly speaking, the separation and recovery method for unburned waste after manufacturing and degreasing does not include the recycling degreasing of step (E) in the common separation and recovery route. The separation and recovery routes for rare earth components and metal components are steps that occur after the resin components have been degreased, so they are the same in the separation and recovery method for unburned waste before manufacturing and degreasing and the separation and recovery method for unburned waste after manufacturing and degreasing.

[0138] (3) Effects According to the above separation and recovery method, it is possible to separate and recover not only the metal components constituting the internal electrode layers but also the rare earth components added to the ceramic powder constituting the ceramic layers from the unfired waste after production and degreasing. This will be specifically described below.

[0139] First, the inventors of the present application have newly focused on the separation and recovery of metal components and rare earth components from unfired waste discharged from the manufacturing process of multilayer ceramic capacitors before firing (firing of laminated chips) and after degreasing. Specifically, the inventors have newly focused on the fact that in unfired waste discharged from the manufacturing process of degreasing before firing (firing of laminated chips), the materials constituting the unfired waste after degreasing, such as metal powder, ceramic powder (first and second ceramic powders), and rare earth powder, are generally not chemically bonded to each other by sintering, and at least some of the powders of each material remain adhered to each other. Therefore, the unfired waste after degreasing can be easily separated into individual materials by a pulverization process (B) or other such process. Furthermore, because the metal components and rare earth components in the unfired waste after degreasing are materials used in the manufacturing of multilayer ceramic capacitors, the purity of the metal components and rare earth components is higher than that of naturally occurring ores. Therefore, by carrying out the above separation and recovery method starting from unburned waste after production and degreasing, it is possible to separate and recover high-purity metal components and high-purity rare earth components.

[0140] In addition, the unfired waste after production and degreasing, after being pulverized, can be separated into a metal powder-containing material and a rare earth powder-containing material by using a magnet in step (C). Then, in step (D), the rare earth powder-containing material is dissolved in a mineral acid to produce a rare earth component-containing solution in which the rare earth powder contained in the rare earth powder-containing material is dissolved as a rare earth component. In step (D), the first ceramic powder contained in the rare earth powder-containing material reacts with the mineral acid and precipitates as an undissolved substance, so the first ceramic powder and the rare earth powder contained in the rare earth powder-containing material are separated. Furthermore, since the unfired waste after production and degreasing has not been fired (fired into a laminated chip), in the rare earth powder-containing material, for example, the rare earth powder is attached to the surface of the first ceramic powder, and the first ceramic powder and the rare earth powder are not sintered. Therefore, the first ceramic powder and the rare earth powder are easily separated by the dissolution in step (D).

[0141] By carrying out the separation and recovery method including the steps (C) and (D), it is possible to separate and recover rare earth components from the unburned waste after pulverization and degreasing. Furthermore, the proportion of rare earth components in the material containing rare earth components increases as each step is carried out. Therefore, it is possible to recover rare earth components such as Dy at high quality.

[0142] Furthermore, by treating the metal powder-containing material by electrolytic refining in step (H), the metal components in the metal powder-containing material can be recovered. Furthermore, by using electrolytic refining, hydrogen is not generated when the metal components in the metal powder-containing material are ionized, and the metal components can be recovered safely. Furthermore, by using electrolytic refining, the metal components can be recovered with relatively high purity.

[0143] By carrying out the separation and recovery method including the steps (C) and (H), it is possible to separate and recover metal components from the unburned waste after pulverization and degreasing. Furthermore, the proportion of metal components in the material containing metal components increases as each step is carried out. Therefore, it is possible to recover metal components such as Ni at high quality.

[0144] As described above, the unfired waste after degreasing in the manufacturing process of a multilayer ceramic capacitor is used to separate and recover metal components, rare earth components, etc., so instead of discarding the unfired waste after degreasing in the manufacturing process, it can be used as a resource and the environmental load can be reduced.

[0145] 2.2 Modifications Modifications of the separation and recovery method for unburned waste before burning and after production and degreasing will be described below.

[0146] (1) Generation of Slurry in Step (B) (1-1) Generation of Slurry Using an Organic Solvent In the above-described embodiment, the unburned waste after manufacturing and degreasing is pulverized and refined in step (B). However, as long as the unburned waste after manufacturing and degreasing can be refined, the unburned waste after manufacturing and degreasing may be refined by, for example, dispersing it in an organic solvent to form a slurry, in addition to or instead of the refinement in step (B) (particularly, refinement by pulverization). Here, the refinement in which the unburned waste after manufacturing and degreasing is mixed with a solvent (such as an organic solvent or an aqueous solvent) to form a slurry is referred to as wet refinement. Furthermore, among the wet refinement methods, the refinement in which the unburned waste after manufacturing and degreasing is pulverized in a slurry formed by mixing the unburned waste after manufacturing and degreasing with a solvent is referred to as wet grinding.

[0147] In this case, the separation and recovery method includes, as a common separation and recovery route, the following steps in this order: preparation of unburned waste after production and degreasing in step (A); mixing of the unburned waste after production and degreasing with an organic solvent (carried out together with or instead of the pulverization (particularly pulverization by grinding) in step (B)); and magnetic separation in step (C). When the unburned waste after production and degreasing is mixed with an organic solvent in this way, it is preferable to further include a distillation step for removing the organic solvent after the magnetic separation in step (C).

[0148] The separation and recovery method further includes dissolution of a rare earth powder-containing material in step (D) as a route for separating and recovering rare earth components, following the common separation and recovery route. The rare earth component separation and recovery route may additionally include filtration in step (F) and neutralization in step (G). The separation and recovery method further includes electrolytic refining in step (H) as a route for separating and recovering metal components, following the common separation and recovery route. The metal component separation and recovery route may additionally include various treatments in step (I).

[0149] That is, the separation and recovery method preferably includes, as a common separation and recovery route, the steps of preparing unburned waste after manufacturing and degreasing in step (A), mixing the unburned waste after manufacturing and degreasing with an organic solvent to produce a slurry, pulverizing the waste (particularly, pulverizing by grinding) in step (B), and magnetic separation in step (C) in this order, and further includes a step of distilling off the organic solvent after the magnetic separation in step (C). By changing the order of this common separation and recovery route, the steps of preparing unburned waste after manufacturing and degreasing in step (A), pulverizing the waste (particularly, pulverizing by grinding) in step (B), mixing the unburned waste after manufacturing and degreasing that has been pulverized by grinding with an organic solvent to produce a slurry, and magnetic separation in step (C) are preferably performed in this order, and further includes a step of distilling off the organic solvent after the magnetic separation in step (C). Alternatively, a common separation and recovery route may omit the pulverization (particularly pulverization by grinding) of step (B), and may include, for example, the steps of preparing unburned waste after production and degreasing in step (A), mixing the unburned waste after production and degreasing with an organic solvent to produce a slurry, and magnetic separation in step (C), in this order, and may further include a distillation step to remove the organic solvent after the magnetic separation in step (C).

[0150] Examples of the organic solvent include alcohol-based organic solvents and hydrocarbon-based organic solvents, such as methanol, ethanol, propanol, toluene, xylene, cyclohexane, and mixtures thereof.

[0151] Furthermore, in the above embodiment, during the magnetic separation in step (C), the unburned waste after manufacturing and degreasing that has been pulverized in step (B) is mixed with and dispersed in water or an organic solvent to form a slurry. However, as described above, if the unburned waste after manufacturing and degreasing is pulverized using an organic solvent in addition to or instead of pulverization in step (B), this slurried unburned waste after manufacturing and degreasing may be magnetically separated in step (C). In other words, the effort of generating a slurry in the magnetic separation in step (C) can be omitted.

[0152] (1-2) Generation of Slurry Using an Aqueous Solvent Although the slurry is generated using an organic solvent in the above, the slurry may also be generated using an aqueous solvent. The separation and recovery method includes, as a common separation and recovery route, the preparation of unburned waste after production and degreasing in step (A), mixing the unburned waste after production and degreasing with an aqueous solvent (performed in conjunction with or instead of the pulverization (particularly pulverization by grinding) in step (B)), and magnetic separation in step (C), in this order. The separation and recovery method also includes, following the common separation and recovery route, dissolution of a rare earth powder-containing material in step (D) as a separation and recovery route for a rare earth component. The separation and recovery route for a rare earth component may additionally include filtration in step (F) and neutralization in step (G). The separation and recovery method also includes electrolytic refining in step (H) as a separation and recovery route for a metal component, following the common separation and recovery route. In addition, various treatments in step (I) may be carried out as an additional route for separating and recovering metal components.

[0153] That is, the separation and recovery method includes, as a common separation and recovery route, for example, step (A) of preparing unburned waste after manufacturing and degreasing, mixing the unburned waste after manufacturing and degreasing with an aqueous solvent to produce a slurry, step (B) of pulverization (particularly, pulverization by grinding), and step (C) of magnetic separation, in this order. By changing the order of this common separation and recovery route, step (A) of preparing unburned waste after manufacturing and degreasing, step (B) of pulverization (particularly, pulverization by grinding), mixing the unburned waste after manufacturing and degreasing pulverized by grinding with an aqueous solvent to produce a slurry, and step (C) of magnetic separation can also be performed in this order. Alternatively, by omitting step (B) of pulverization (particularly, pulverization by grinding), the common separation and recovery route can include, for example, step (A) of preparing unburned waste after manufacturing and degreasing, mixing the unburned waste after manufacturing and degreasing with an aqueous solvent to produce a slurry, and step (C) of magnetic separation, in this order. As the aqueous solvent, for example, water can be used.

[0154] Furthermore, in the above-described embodiment, during the magnetic separation in step (C), the unburned waste after manufacturing and degreasing that has been pulverized in step (B) is mixed with and dispersed in water or an organic solvent to form a slurry. However, as described above, when the unburned waste after manufacturing and degreasing is formed into a slurry state using an aqueous solvent in step (B), the unburned waste after manufacturing and degreasing that has become a slurry state may be magnetically separated in step (C). In other words, the effort of forming a slurry state in the magnetic separation in step (C) can be omitted.

[0155] (2) Unfired Waste After Degreasing: The manufacturing method for the multilayer ceramic capacitor 10 that can generate the unfired waste after degreasing includes, in order, forming a laminate block (step 3), cutting into laminate chips (step 4), degreasing (step 5), firing the laminate chips (step 6), and applying and firing a base electrode layer paste (step 7). However, the manufacturing method for the multilayer ceramic capacitor 10 is not limited thereto. For example, the unfired laminate chips may be subjected to degreasing (step 5) and firing (step 6) after applying a base electrode layer paste to the unfired laminate chips. Specifically, the laminate chips before degreasing (step 5) are first coated with a base electrode layer paste containing Ni, glass components, resin components, etc. Next, the laminate chips coated with the base electrode layer paste are degreased and then fired. The temperature during degreasing is preferably, for example, higher than 800°C and lower than 1000°C. The firing temperature is preferably, for example, higher than 1000°C and not higher than 1400°C. These steps are performed after cutting into laminated chips in step 4 of the above-mentioned manufacturing method and before the plating step in step 8. In these steps, the firing of the laminated chips in step 6 and the firing of the base electrode layer paste in step 7 are performed in a single firing. Considering this manufacturing method, the unfired waste after manufacturing and degreasing includes, in addition to the waste listed above, unfired laminated chip waste after the application of the base electrode layer paste (before the firing in step 6 and step 7 is performed simultaneously). In this case, the Ni powder in the base electrode layer paste is included in the target for separation and recovery. The base electrode layer paste may further contain a co-material made of ceramic powder.

[0156] As described above, although the embodiments of the present invention have been disclosed in the above description, the present invention is not limited thereto. In other words, various modifications can be made to the above-described embodiments in terms of mechanism, shape, material, quantity, position, arrangement, etc., without departing from the scope of the technical idea and purpose of the present invention, and such modifications are included in the present invention.

[0157] <Other Modifications> Modifications applicable to both the separation and recovery method for unfired waste before firing and before degreasing, and the separation and recovery method for unfired waste before firing and after degreasing, are described below. (1) Other Multilayer Ceramic Capacitors Discharged with Unfired Waste Before Degreasing or Unfired Waste After Degreasing In the above embodiment, a two-terminal multilayer ceramic capacitor having two terminals, a first external electrode 30a and a second external electrode 30b, was described as the multilayer ceramic capacitor to be manufactured. However, the scope of application of the present invention is not limited to unfired waste before degreasing or unfired waste after degreasing, which are discharged during the manufacturing process of a two-terminal multilayer ceramic capacitor. The present invention is applicable to unfired waste before degreasing or unfired waste after degreasing, which are discharged during the manufacturing process of a multilayer ceramic capacitor having internal electrode layers containing metal powder such as Ni and ceramic layers containing a dielectric material such as BaTiO3 and a rare earth powder additive such as Dy. Therefore, the present invention may be applied to, for example, unsintered waste before degreasing during production or unsintered waste after degreasing during production, which is discharged in the manufacturing process of a three-terminal multilayer ceramic capacitor.

[0158] For example, a three-terminal multilayer ceramic capacitor may include a laminate 12 similar to that of the above-described embodiment and first to fourth external electrodes. The internal electrode layers 16 include a first internal electrode layer extending to the first end face 12e and the second end face 12f, and a second internal electrode layer extending to the first side face 12c and the second side face 12d. A first external electrode is disposed on the first end face 12e of the laminate 12. The first external electrode is electrically connected to the first internal electrode layer exposed at the first end face 12e of the laminate 12. A second external electrode is disposed on the second end face 12f of the laminate 12. The second external electrode is electrically connected to the first internal electrode layer exposed at the second end face 12f of the laminate 12. A third external electrode is disposed on the first side face 12c of the laminate 12. The third external electrode is electrically connected to the second internal electrode layer exposed at the first side face 12c of the laminate 12. A fourth external electrode is disposed on the second side surface 12d of the laminate 12. The fourth external electrode is electrically connected to the second internal electrode layer exposed at the second side surface 12d of the laminate 12.

[0159] (2) Regarding the filtration step (F), when the rare earth powder-containing material is dissolved in a mineral acid in step (D), the first ceramic powder contained in the rare earth powder-containing material reacts with the mineral acid to form an undissolved substance and precipitate. Meanwhile, the rare earth powder dissolves to produce a rare earth component-containing solution. This rare earth component-containing solution containing the undissolved substance can also be recovered as the rare earth component. In this case, the solid-liquid separation step (F), such as filtration, can be omitted.

[0160] (3) Omission of Neutralization in Step (G) In the above embodiment, in the dissolution of the rare earth powder-containing material in Step (D), the rare earth component can be separated and recovered as a rare earth component-containing solution. Therefore, the neutralization in Step (G) can be omitted.

[0161] (4) Omission of Various Treatments in Step (I) In the above embodiment, metal components can be separated and recovered in the electrolytic refining in Step (H), so that various treatments in Step (I) can be omitted.

[0162] (5) Other methods for separating and recovering rare earth components In the above-described embodiment, rare earth component compounds such as Dy(OH) are separated and recovered as rare earth components in the neutralization step (G). However, the method for separating and recovering rare earth components is not limited to this. For example, the rare earth components can be recovered as follows.

[0163] (a) The rare earth component compound obtained by the neutralization in step (G) is heat-treated to produce an oxide, which can be recovered as a rare earth component. For example, if the rare earth component compound obtained after the neutralization in step (G) is Dy(OH), dysprosium oxide (DyO) can be recovered as a rare earth component by heat-treating Dy(OH).

[0164] (b) The rare earth component compound obtained by the neutralization in step (G) is dissolved in hydrochloric acid to produce a chloride, which can be recovered as a rare earth component. For example, if the rare earth component compound obtained after the neutralization in step (G) is Dy(OH), a dysprosium chloride (DyCl) solution is produced by dissolving Dy(OH) in hydrochloric acid. The dysprosium chloride solution is distilled off to evaporate the solvent, and dysprosium chloride hexahydrate (DyCl.6H0) can be recovered as a rare earth component.

[0165] (c) As in (b) above, a dysprosium chloride solution is produced by dissolving Dy(OH)3, the rare earth component compound obtained after neutralization in step (G), in hydrochloric acid. This can then be further purified to recover a high-purity rare earth component. For example, the dysprosium chloride solution produced as described above can be purified by solvent extraction, and a high-purity dysprosium chloride solution can be recovered as a rare earth component. Solvent extraction is a separation and purification method that utilizes solute partitioning, in which a solute dissolved in one of the immiscible liquids, an oil phase and an aqueous phase, is transferred to the other. Methods other than solvent extraction, such as an ion exchange resin method, can also be used.

[0166] (d) High-purity dysprosium oxide (DyO) can also be recovered from the high-purity dysprosium chloride solution obtained by the solvent extraction described in (c) above. In this case, for example, oxalic acid is first added to the high-purity dysprosium chloride solution to precipitate dysprosium oxalate. This is then filtered to recover high-purity dysprosium oxalate hexahydrate (Dy(C0)6H0). By heat-treating this high-purity dysprosium oxalate hexahydrate, high-purity dysprosium oxide (DyO) can be recovered as a rare earth component.

[0167] (e) High-purity dysprosium chloride hexahydrate can also be recovered from the high-purity dysprosium chloride solution obtained by the solvent extraction described in (c) above. In this case, for example, high-purity dysprosium chloride hexahydrate is recovered by distilling off the high-purity dysprosium chloride solution and evaporating the solvent.

[0168] (f) In the above embodiment, the rare earth component-containing solution separated and recovered in the filtration of step (F) is introduced into the neutralization of step (G). However, the rare earth component-containing solution separated and recovered in the filtration of step (F) may be treated in a rare earth component concentration step and then introduced into the neutralization of step (G). In other words, the rare earth component concentration step is performed after the filtration of step (F) and before the neutralization of step (G).

[0169] The rare earth component concentration step is not limited as long as it can improve the recovery amount of the rare earth component in the rare earth component-containing solution. Examples of the rare earth component concentration step include, but are not limited to, (f1) ion exchange method, (f2) solvent extraction method, and (f3) distillation of the solvent from the solution. Each of (f1) to (f3) will be described below as a representative example.

[0170] (f1) Ion Exchange Method: The ion exchange method is a method in which dissolved ions in a solvent are adsorbed onto an ion exchanger such as an ion exchange resin or a chelating resin. For example, by passing a solution containing rare earth components through an ion exchanger, the rare earth components in the solution are adsorbed onto the ion exchanger. The ion exchange method is not limited, but may be carried out, for example, by passing the solution containing rare earth components through a column packed with an ion exchanger. For example, the column is formed of a cylindrical body with open top and bottom ends, and the solution containing rare earth components is introduced into the column from the top side of the column, and the rare earth components are adsorbed onto the ion exchanger during the process of passing through the ion exchanger. The remaining solution containing rare earth components after passing through the ion exchanger is discharged from the bottom side of the column.

[0171] Next, the rare earth components adsorbed on the ion exchanger are eluted from the ion exchanger using an eluent. For example, the eluent is passed through the lower end of a column packed with the ion exchanger on which the rare earth components are adsorbed. As a result, the rare earth components are eluted from the ion exchanger by the eluent. The eluent containing the eluted rare earth components is recovered from the upper end of the column. The rare earth components can be recovered by filtering the eluent containing the dissolved rare earth components, for example, using a filter. Depending on the processing volume of the rare earth component-containing solution, the ease of adsorption of the rare earth components to the ion exchanger, the amount of eluent, and other factors, the concentration of the rare earth components contained in the eluent can be made higher than the concentration of the rare earth components contained in the rare earth component-containing solution.

[0172] In the above example, the rare earth component-containing solution is passed through the column from the top to the bottom, and then the eluent is passed through the column from the bottom to the top. However, the direction in which the rare earth component-containing solution and the eluent are passed through the column is not limited as long as the rare earth components can be dissolved in the eluent after being adsorbed onto the ion exchanger.

[0173] Alternatively, the series of steps (1) including steps (A) to (F) and the rare earth component concentration step by ion exchange may be carried out only once. For example, the series of steps (1) is carried out only once by passing the rare earth component-containing solution after steps (A) to (F) through an ion exchanger once.

[0174] Alternatively, a series of steps (1) including steps (A) to (F) and a rare earth component concentration step by ion exchange may be performed multiple times. For example, the series of steps (1) in which the rare earth component-containing solution after steps (A) to (F) is passed through an ion exchanger may be performed multiple times. In this case, the same ion exchanger may be used in each series of steps (1). By passing the rare earth component-containing solution recovered from steps (A) to (F) multiple times through the same ion exchanger, more rare earth components are adsorbed onto the ion exchanger than in the rare earth component-containing solution recovered from a single run of steps (A) to (F). This increases the concentration of the rare earth components in the eluent and increases the amount of rare earth components recovered.

[0175] Alternatively, a series of steps (2) including steps (A) to (F) may be performed multiple times, and the rare earth component-containing solution obtained in each series of steps (2) may then be temporarily stored. The stored rare earth component-containing solution may then be processed all at once in a rare earth component concentration step using ion exchange. The amount of rare earth component-containing solution stored after multiple series of steps (2) is greater than the amount of rare earth component-containing solution obtained from a single series of steps (2). Therefore, by passing the stored rare earth component-containing solution through an ion exchanger, a larger amount of rare earth component can be adsorbed onto the ion exchanger, thereby increasing the amount of rare earth component recovered.

[0176] In addition, if the concentration of rare earth components in the rare earth component-containing solution after one cycle of the series of steps (A) to (F) in step (2) is low, the amount of rare earth components deposited on the filter will be small even if the rare earth component-containing solution is filtered using a filter. Therefore, the recovery amount of the rare earth components may not be high. However, the recovery amount of the rare earth components can be increased by performing the rare earth component concentration step as described above.

[0177] Examples of ion exchange resins that serve as ion exchangers include, but are not limited to, cation exchange resins and chelating resins. Examples of cation exchange resins include, but are not limited to, gel-type cation exchange resins, strong acid cation exchange resins, and weak acid cation exchange resins. Specific examples of cation exchange resins include, but are not limited to, Amberlite IR-120B (manufactured by Organo Corporation), Duolite C20J (manufactured by Sumika Chemtex Co., Ltd.), DIAION SK-110 (manufactured by Mitsubishi Chemical Corporation), and Purolite C100 (manufactured by Purolite Co., Ltd.).

[0178] Examples of chelating resins that are ion exchangers include, but are not limited to, resins having chelating groups or chelating capabilities such as thiourea groups, thiouronium groups, phosphonic acid, aminophosphoric acid, aminocarboxylic acid, alkylamino groups, pyridine rings, cyclic cyanines, and cyclic ethers. Specific examples of chelating resins include, but are not limited to, Sumichelate MC700 (manufactured by Sumika Chemtex Co., Ltd.) and Purolite MTS9300 (manufactured by Purolite Co., Ltd.).

[0179] (f2) Solvent Extraction Method The solvent extraction method comprises, for example, a solvent extraction step and a stripping step. The solvent extraction step is a step of contacting and mixing a water-insoluble organic phase containing a metal extractant with a rare earth-containing solution to separate rare earth components from the rare earth-containing solution. After the solvent extraction step, a phase separation step is performed to separate the rare earth-containing water-insoluble organic phase from the aqueous phase. The phase separation step utilizes the difference in specific gravity between the rare earth-containing water-insoluble organic phase and the aqueous phase that have undergone the solvent extraction step.

[0180] In the back-extraction step, the rare earth-containing water-insoluble organic phase obtained through the phase separation step is brought into contact with and mixed with an acidic aqueous solution, thereby allowing the rare earth components in the water-insoluble organic phase to be back-extracted into the acidic aqueous solution.

[0181] Alternatively, the series of steps (1) including steps (A) to (F) and the step of concentrating the rare earth components by solvent extraction may be carried out only once.

[0182] Alternatively, a series of steps (1) including steps (A) to (F) and a rare earth component concentration step by solvent extraction may be performed multiple times. For example, a series of steps (1) in which the rare earth component-containing solution after steps (A) to (F) is mixed with an organic solvent may be performed multiple times. For example, by repeatedly mixing the rare earth component-containing solution recovered from steps (A) to (F) multiple times with the same organic solvent, more rare earth components are transferred to the organic solvent than when the rare earth component-containing solution recovered from steps (A) to (F) is mixed with an organic solvent once. Therefore, the amount of rare earth components recovered can be increased.

[0183] Alternatively, a series of steps (2) including steps (A) to (F) may be carried out multiple times, and the rare earth component-containing solution obtained in each series of steps (2) may be temporarily stored. Thereafter, the stored rare earth component-containing solution may be treated all at once in a rare earth component concentration step using a solvent extraction method.

[0184] (f3) Removal of solvent from solution Removal of solvent from solution involves removing the solvent from a solution containing dissolved ions. Removal of the solvent can be performed using, for example, but not limited to, an evaporator. An evaporator is a device that evaporates the solvent by, for example, heating and reducing the pressure inside an evaporator into which the solution has been introduced. Examples of evaporators include rotary evaporators and flash evaporators. The operating conditions of the evaporator are appropriately adjusted depending on the amount of unburned waste to be processed before or after the production and degreasing, the various components added to the unburned waste, and the like.

[0185] Furthermore, the series of steps (1) including steps (A) to (F) and the step of concentrating the rare earth component by distilling off the solvent from the solution may be carried out only once or may be carried out multiple times.

[0186] Alternatively, a series of steps (2) including steps (A) to (F) may be carried out multiple times, and the rare earth component-containing solution obtained in each series of steps (2) may be temporarily stored. Thereafter, the stored rare earth component-containing solution may be treated all at once to distill off the solvent.

[0187] (g) State of rare earth component The recovered rare earth component may be in a liquid state, a solid state, or a mixture of liquid and solid. The crystal lattice of the rare earth component may be in an amorphous state, a crystalline state, or a mixture of amorphous and crystalline states.

[0188] (6) Other methods for separating and recovering metal components In the above-described embodiment, the metal components are separated and recovered as metal component compounds in the various treatments of step (I). However, the separation and recovery of the metal components is not limited to this. For example, the metal components can be recovered as follows.

[0189] (a) A metal component compound can be recovered as a metal component by crystallizing the metal component-containing solution. For example, if the metal component-containing solution obtained after the various treatments in step (I) is a nickel sulfate (NiSO4) solution, nickel sulfate hexahydrate (NiSO4.6H2O) can be recovered as a metal component by crystallizing and filtering the nickel sulfate solution.

[0190] (b) High-purity metal components can be recovered by purifying the metal component-containing solution obtained by reacting the metal components with the solution in the various treatments of step (I). For example, a nickel sulfate (NiSO4) solution, which is a metal component-containing solution, can be purified by an ion exchange resin method, a solvent extraction method, or the like, and a high-purity nickel sulfate solution can be recovered as the metal components.

[0191] (c) The high-purity nickel sulfate solution recovered in (b) above is crystallized and filtered to recover nickel sulfate hexahydrate (NiSO4.6H2O) as the metal component.

[0192] (d) By treating the high-purity Ni recovered by the electrolytic refining in step (H), nickel chloride hexahydrate (NiCl.6H0) can be recovered as a metal component. For example, by dissolving the high-purity Ni recovered by the electrolytic refining in step (H) in hydrochloric acid, a high-purity nickel chloride (NiCl) solution is produced. By spray-drying the nickel chloride solution, high-purity nickel chloride hexahydrate is produced. By further drying the high-purity nickel chloride hexahydrate with hot air, even higher-purity nickel chloride hexahydrate can be recovered as a metal component.

[0193] (e) The metal component-containing solution resulting from the reaction between the metal component and the solution in the various treatments of step (I) can be neutralized to produce chlorides, and the chlorides can be recovered as the metal component. For example, a nickel sulfate solution, which is the metal component-containing solution, is neutralized by adjusting the solution to, for example, approximately pH 10 (pH 9 or higher and pH 11 or lower) with an alkali such as sodium hydroxide or potassium hydroxide, thereby precipitating nickel hydroxide (Ni(OH)). The precipitated nickel hydroxide (Ni(OH)) is separated and recovered, for example, by filtration. Furthermore, nickel hydroxide is dissolved in hydrochloric acid to produce a nickel chloride (NiCl) solution. Next, nickel chloride hexahydrate (NiCl.6H0) can be recovered as the metal component by distilling off the nickel chloride solution and evaporating the solvent.

[0194] (g) State of Metal Component The recovered metal component may be in a liquid state, a solid state, or a mixture of liquid and solid. The crystal lattice of the metal component may be in an amorphous state, a crystalline state, or a mixture of amorphous and crystalline states.

[0195] <1> A method for separating and recovering rare earth components and metal components from unsintered waste before degreasing, comprising: (A) a step of preparing unsintered waste before degreasing and before firing of laminated chips discharged in a manufacturing process of a multilayer ceramic capacitor, the unsintered waste before degreasing and before production, the unsintered waste before degreasing and before production, comprising a magnetic metal powder, a ceramic powder, a rare earth powder, and a resin component, wherein the metal powder and the ceramic powder are at least partially adhered to each other; (B) a step of micronizing the unsintered waste before degreasing and before production, (C) a step of separating and recovering the unsintered waste before degreasing and before production after undergoing step (B) into a metal powder-containing material containing the metal powder and the ceramic powder, and a rare earth powder-containing material containing the rare earth powder and the ceramic powder, using a magnet; and (H) a step of recovering metal components constituting the metal powder from the metal powder-containing material after undergoing step (C) by electrolytic refining.

[0196] <2> The method for separating and recovering rare earth elements and metal elements from unburned waste before production and degreasing according to <1>, wherein the metal powder-containing material is introduced into the step (H) in a state where the metal powder is processed into a mass in which the metal powders are in contact with each other to an extent that current can flow in the electrolytic refining.

[0197] <3> The method for separating and recovering rare earth components and metal components from unburned waste before production and degreasing according to <1> or <2>, wherein in the step (B), the unburned waste before production and degreasing is pulverized in a slurry produced by mixing the unburned waste before production and degreasing with a solvent, the pulverized unburned waste before production and degreasing is mixed with a solvent to produce a slurry, or the unburned waste before production and degreasing is pulverized by pulverization.

[0198] <4> (E) A process for recycling and degreasing the resin component from the unburned waste before production and degreasing described in <1> or <2> is included between the process (A) and the process (H).

[0199] <5> The method for separating and recovering rare earth components and metal components from unburned waste before production and degreasing according to <1> or <2>, wherein the step (E) is a step of recycling and degreasing the resin component from the unburned waste before production and degreasing between the step (A) and the step (B), or recycling and degreasing the resin component from the unburned waste before production and degreasing between the step (B) and the step (C), or a step of recycling and degreasing the resin component from the metal powder-containing material after the step (C) and the rare earth powder-containing material after the step (C), respectively, after the step (C).

[0200] <6> The method for separating and recovering rare earth components and metal components from unburned waste before production degreasing according to <4> or <5>, wherein the degreasing temperature during recycling degreasing in the step (E) is 600°C or higher and 1000°C or lower.

[0201] <7> The method for separating and recovering rare earth components and metal components from unburned waste before production and degreasing according to any one of <1> to <6>, wherein the ceramic powder includes a first ceramic powder and a second ceramic powder having a particle size smaller than that of the first ceramic powder, the metal powder and the second ceramic powder are at least partially adhered to each other in the metal powder-containing material, and the rare earth powder and the first ceramic powder are at least partially adhered to each other in the rare earth powder-containing material.

[0202] <8> The method for separating and recovering rare earth components and metal components from unburned waste before production and degreasing according to any one of <1> to <7>, wherein the metal component is Ni and the ceramic powder is BaTiO3.

[0203] <9> The method for separating and recovering rare earth components and metal components from unburned waste before production and degreasing according to any one of <1> to <8>, further comprising the step of (D) dissolving the rare earth powder-containing material after the step (C) in at least one mineral acid selected from the group consisting of sulfuric acid, nitric acid, and hydrochloric acid, thereby precipitating the ceramic powder in the rare earth powder-containing material and producing a rare earth component-containing solution in which the rare earth powder in the rare earth powder-containing material is dissolved as a rare earth component.

[0204] <10> (F) The method for separating and recovering rare earth components and metal components from unburned waste before production degreasing according to <9>, further comprising a step of solid-liquid separating the rare earth component-containing solution containing the precipitated ceramic powder.

[0205] <11> The method for separating and recovering rare earth components and metal components from unburned waste before production and degreasing according to <10>, further comprising a rare earth component concentration step of concentrating the rare earth components in the rare earth component-containing solution after the step (F).

[0206] <12> (G) The method for separating and recovering rare earth components and metal components from unburned waste before production and degreasing according to any one of <9> to <11>, further comprising a step of neutralizing the rare earth component-containing solution to precipitate and recover the rare earth components.

[0207] <13> The method for separating and recovering rare earth components and metal components from unburned waste before production and degreasing according to <12>, wherein in the step (G), the rare earth components are recovered by adjusting the pH of the rare earth component-containing solution to a value of 6 or more and 9 or less.

[0208] <14> The method for separating and recovering rare earth components and metal components from unburned waste before production and degreasing according to any one of <8> to <12>, wherein in the step (D), the rare earth component-containing solution is adjusted to a pH of 1.5 or more and 2.5 or less by adding the mineral acid.

[0209] <15> The method for separating and recovering rare earth components and metal components from unburned waste before production and degreasing according to any one of <9> to <14>, wherein the rare earth component is at least one of Dy, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb, and Lu.

[0210] <16> A method for separating and recovering rare earth components and metal components from unsintered waste after degreasing, comprising: (A) a step of preparing unsintered waste after degreasing and before firing of laminated chips discharged in a manufacturing process of a multilayer ceramic capacitor, the unsintered waste after degreasing and before production, the unsintered waste containing a magnetic metal powder, a ceramic powder, and a rare earth powder, the metal powder and the ceramic powder at least partially adhering to each other, and the resin component being degreased in the manufacturing process; (B) a step of micronizing the unsintered waste after degreasing and before production; (C) a step of separating and recovering the unsintered waste after degreasing and before production after production after degreasing after step (B) into a metal powder-containing material containing the metal powder and the ceramic powder, and a rare earth powder-containing material containing the rare earth powder and the ceramic powder, using a magnet; and (H) a step of recovering metal components constituting the metal powder from the metal powder-containing material after step (C) by electrolytic refining.

[0211] <17> The method for separating and recovering rare earth elements and metal elements from unburned waste before production and degreasing according to <16>, wherein the metal powder-containing material is introduced into the step (H) in a state where the metal powder is processed into a mass in which the metal powders are in contact with each other to an extent that current can flow in the electrolytic refining.

[0212] <18> The method for separating and recovering rare earth components and metal components from unburned waste before production and degreasing according to <16> or <17>, wherein in the step (B), the unburned waste before production and degreasing is pulverized in a slurry produced by mixing the unburned waste before production and degreasing with a solvent, the pulverized unburned waste before production and degreasing is mixed with a solvent to produce a slurry, or the unburned waste before production and degreasing is pulverized by grinding.

[0213] <19> The method for separating and recovering rare earth components and metal components from unburned waste before production and degreasing according to any one of <16> to <18>, wherein the ceramic powder includes a first ceramic powder and a second ceramic powder having a particle size smaller than that of the first ceramic powder, the metal powder and the second ceramic powder are at least partially adhered to each other in the metal powder-containing material, and the rare earth powder and the first ceramic powder are at least partially adhered to each other in the rare earth powder-containing material.

[0214] <20> The method for separating and recovering rare earth components and metal components from unburned waste before production and degreasing according to any one of <16> to <19>, wherein the metal component is Ni and the ceramic powder is BaTiO3.

[0215] <21> The method for separating and recovering rare earth components and metal components from unburned waste before production and degreasing according to any one of <16> to <20>, further comprising the step of: (D) dissolving the rare earth powder-containing material after the step (C) in at least one mineral acid selected from the group consisting of sulfuric acid, nitric acid, and hydrochloric acid, thereby precipitating the ceramic powder in the rare earth powder-containing material and producing a rare earth component-containing solution in which the rare earth powder in the rare earth powder-containing material is dissolved as a rare earth component.

[0216] <22> (F) The method for separating and recovering rare earth components and metal components from unburned waste before production and degreasing according to <21>, further comprising a step of solid-liquid separating the rare earth component-containing solution containing the precipitated ceramic powder.

[0217] <23> The method for separating and recovering rare earth components and metal components from unburned waste before production and degreasing according to <22>, further comprising a rare earth component concentration step of concentrating the rare earth components in the rare earth component-containing solution after the step (F).

[0218] <24> (G) The method for separating and recovering rare earth components and metal components from unburned waste before production and degreasing according to any one of <21> to <23>, further comprising a step of neutralizing the rare earth component-containing solution to precipitate and recover the rare earth components.

[0219] <25> The method for separating and recovering rare earth components and metal components from unburned waste before production and degreasing according to <24>, wherein in the step (G), the rare earth components are recovered by adjusting the pH of the rare earth component-containing solution to a value of 6 or more and 9 or less.

[0220] <26> The method for separating and recovering rare earth components and metal components from unburned waste before production and degreasing according to any one of <20> to <24>, wherein in the step (D), the rare earth component-containing solution is adjusted to a pH of 1.5 or more and 2.5 or less by adding the mineral acid.

[0221] <27> The method for separating and recovering rare earth components and metal components from unburned waste before production and degreasing according to any one of <21> to <26>, wherein the rare earth component is at least one of Dy, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb, and Lu.

[0222] 10: Multilayer ceramic capacitor 12: Laminate 12a: First main surface 12b: Second main surface 12c: First side surface 12d: Second side surface 12e: First end surface 12f: Second end surface 14: Ceramic layer 14_U: Unsintered ceramic layer 16: Internal electrode layer 16_U: Unsintered internal electrode layer 16a: First internal electrode layer 16b: Second internal electrode layer 30: External electrode 30a: First external electrode 30b: Second external electrode 32: Base electrode layer 32a: First base electrode layer 32b: Second base electrode layer 34: Plating layer 34a: First plating layer 34b: Second plating layer x: Height direction y: Width direction z : Length direction

Claims

1. A method for separating and recovering rare earth components and metal components from unsintered waste before degreasing, comprising: (A) a step of preparing unsintered waste before degreasing and before firing of laminated chips discharged in the manufacturing process of multilayer ceramic capacitors, the unsintered waste before degreasing and before production, comprising a magnetic metal powder, a ceramic powder, a rare earth powder, and a resin component, with the metal powder and the ceramic powder at least partially adhering to each other; (B) a step of micronizing the unsintered waste before degreasing and before production; (C) a step of using a magnet to separate and recover the unsintered waste before degreasing and before production after step (B) into a metal powder-containing material containing the metal powder and the ceramic powder, and a rare earth powder-containing material containing the rare earth powder and the ceramic powder; and (H) a step of recovering the metal components that make up the metal powder from the metal powder-containing material after step (C) by electrolytic refining.

2. A method for separating and recovering rare earth elements and metal elements from unburned waste before production and degreasing as described in claim 1, wherein the metal powder-containing material is introduced into step (H) in a state where it has been processed into a mass in which the metal powders are in contact with each other to the extent that current can flow in the electrolytic refining.

3. A method for separating and recovering rare earth components and metal components from unburned waste before production and degreasing as set forth in claim 1 or claim 2, wherein in step (B), the unburned waste before production and degreasing is pulverized in a slurry produced by mixing the unburned waste before production and degreasing with a solvent, the pulverized unburned waste before production and degreasing is mixed with a solvent to produce a slurry, or the unburned waste before production and degreasing is pulverized by grinding.

4. A method for separating and recovering rare earth components and metal components from unburned waste before production and degreasing as described in claim 1 or claim 2, which includes a step of recycling and degreasing the resin components from the unburned waste before production and degreasing between steps (A) and (H).

5. The method for separating and recovering rare earth components and metal components from unburned waste before production and degreasing as set forth in claim 1 or 2, wherein step (E) is a step of recycling and degreasing the resin components from unburned waste before production and degreasing between step (A) and step (B), or recycling and degreasing the resin components from unburned waste before production and degreasing between step (B) and step (C), or a step of recycling and degreasing the resin components from the metal powder-containing material after step (C) and the rare earth powder-containing material after step (C), respectively, after step (C).

6. A method for separating and recovering rare earth elements and metal elements from unburned waste before production degreasing as set forth in claim 4 or claim 5, wherein the degreasing temperature during recycling degreasing in step (E) is 600°C or higher and 1000°C or lower.

7. A method for separating and recovering rare earth components and metal components from unburned waste before production and degreasing as set forth in any one of claims 1 to 6, wherein the ceramic powder comprises a first ceramic powder and a second ceramic powder having a particle size smaller than that of the first ceramic powder, and in the metal powder-containing material, the metal powder and the second ceramic powder are at least partially adhered to each other, and in the rare earth powder-containing material, the rare earth powder and the first ceramic powder are at least partially adhered to each other.

8. A method for separating and recovering rare earth and metal components from unburned waste before production and degreasing as set forth in any one of claims 1 to 7, wherein the metal component is Ni and the ceramic powder is BaTiO3.

9. A method for separating and recovering rare earth components and metal components from unburned waste before production and degreasing as set forth in any one of claims 1 to 8, further comprising the step of (D) dissolving the rare earth powder-containing material after step (C) in at least one mineral acid selected from the group consisting of sulfuric acid, nitric acid, and hydrochloric acid, thereby precipitating the ceramic powder in the rare earth powder-containing material and producing a rare earth component-containing solution in which the rare earth powder in the rare earth powder-containing material is dissolved as a rare earth component.

10. A method for separating and recovering rare earth components and metal components from unburned waste before production degreasing as described in claim 9, further comprising (F) a step of solid-liquid separating the rare earth component-containing solution containing the precipitated ceramic powder.

11. The method for separating and recovering rare earth components and metal components from unburned waste before production and degreasing as set forth in claim 10, further comprising a rare earth component concentration step of concentrating the rare earth components in the rare earth component-containing solution after step (F).

12. (G) A method for separating and recovering rare earth components and metal components from unburned waste before production and degreasing as described in any one of claims 9 to 11, further comprising a step of precipitating and recovering the rare earth components by neutralizing the rare earth component-containing solution.

13. A method for separating and recovering rare earth components and metal components from unburned waste before production and degreasing as described in claim 12, wherein in step (G), the rare earth components are recovered by adjusting the pH of the rare earth component-containing solution to a value between 6 and 9.

14. A method for separating and recovering rare earth components and metal components from unburned waste before production and degreasing, as described in claims 8 to 12, wherein in step (D), the rare earth component-containing solution is adjusted to a pH of 1.5 or higher and 2.5 or lower by adding the mineral acid.

15. A method for separating and recovering rare earth components and metal components from unburned waste before production and degreasing according to any one of claims 9 to 14, wherein the rare earth component is at least one of Dy, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb, and Lu.

16. A method for separating and recovering rare earth components and metal components from unsintered waste after degreasing, comprising: (A) a step of preparing unsintered waste after degreasing that is produced before the firing of laminated chips discharged in the manufacturing process of multilayer ceramic capacitors, the unsintered waste after degreasing, comprising magnetic metal powder, ceramic powder, and rare earth powder, the metal powder and the ceramic powder at least partially adhering to each other, and the resin components being degreased in the manufacturing process; (B) a step of micronizing the unsintered waste after degreasing; (C) a step of using a magnet to separate and recover the unsintered waste after degreasing after process (B) into a metal powder-containing material containing the metal powder and the ceramic powder, and a rare earth powder-containing material containing the rare earth powder and the ceramic powder; and (H) a step of recovering the metal components that make up the metal powder from the metal powder-containing material after process (C) by electrolytic refining.

17. A method for separating and recovering rare earth elements and metal elements from unburned waste before production and degreasing as set forth in claim 16, wherein the metal powder-containing material is introduced into step (H) in a state where it has been processed into a mass in which the metal powder particles are in contact with each other to the extent that current can flow in the electrolytic refining.

18. A method for separating and recovering rare earth components and metal components from unburned waste before production and degreasing as set forth in claim 16 or 17, wherein in step (B), the unburned waste before production and degreasing is pulverized in a slurry produced by mixing the unburned waste before production and degreasing with a solvent, the pulverized unburned waste before production and degreasing is mixed with a solvent to produce a slurry, or the unburned waste before production and degreasing is pulverized by grinding.

19. A method for separating and recovering rare earth components and metal components from unburned waste before production and degreasing as set forth in any one of claims 16 to 18, wherein the ceramic powder comprises a first ceramic powder and a second ceramic powder having a particle size smaller than that of the first ceramic powder, and in the metal powder-containing material, the metal powder and the second ceramic powder are at least partially adhered to each other, and in the rare earth powder-containing material, the rare earth powder and the first ceramic powder are at least partially adhered to each other.

20. A method for separating and recovering rare earth components and metal components from unburned waste before production and degreasing as set forth in any one of claims 16 to 19, wherein the metal component is Ni and the ceramic powder is BaTiO3.

21. A method for separating and recovering rare earth components and metal components from unburned waste before production and degreasing as set forth in any one of claims 16 to 20, further comprising the step of (D) dissolving the rare earth powder-containing material after step (C) in at least one mineral acid selected from the group consisting of sulfuric acid, nitric acid, and hydrochloric acid, thereby precipitating the ceramic powder in the rare earth powder-containing material and producing a rare earth component-containing solution in which the rare earth powder in the rare earth powder-containing material is dissolved as a rare earth component.

22. A method for separating and recovering rare earth components and metal components from unburned waste before production degreasing as described in claim 21, further comprising a step of (F) performing solid-liquid separation of the rare earth component-containing solution containing the precipitated ceramic powder.

23. A method for separating and recovering rare earth components and metal components from unburned waste before production and degreasing as set forth in claim 22, further comprising a rare earth component concentration step of concentrating the rare earth components in the rare earth component-containing solution after step (F).

24. (G) A method for separating and recovering rare earth components and metal components from unburned waste before production and degreasing as described in any one of claims 21 to 23, further comprising a step of neutralizing the rare earth component-containing solution to precipitate and recover the rare earth components.

25. A method for separating and recovering rare earth components and metal components from unburned waste before production and degreasing as described in claim 24, wherein in step (G), the rare earth components are recovered by adjusting the pH of the rare earth component-containing solution to a value between 6 and 9.

26. A method for separating and recovering rare earth components and metal components from unburned waste before production and degreasing, as described in any one of claims 20 to 24, wherein in step (D), the rare earth component-containing solution is adjusted to a pH of 1.5 or higher and 2.5 or lower by adding the mineral acid.

27. A method for separating and recovering rare earth and metal components from unburned waste before production and degreasing as set forth in any one of claims 21 to 26, wherein the rare earth component is at least one of Dy, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb, and Lu.

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