Methods for separating and recovering rare earth and metal components from post-firing waste of multilayer ceramic capacitors

Abstract

This invention provides a method for separating and recovering rare earth and metal components from post-calcination waste. The separation and recovery method of this invention includes the following steps: (A) preparing post-calcination waste of a multilayer ceramic capacitor, wherein the multilayer ceramic capacitor is formed by sintering a ceramic layer, an internal electrode layer containing a magnetic first metal component, and a sintered electrode layer containing a non-magnetic second metal component; (B) a micronization step of the post-calcination waste; (C) using a magnet to separate the waste into a first separate containing ceramic micronization and first metal micronization, and a second separate containing ceramic micronization, rare earth inclusions, and second metal micronization, and recovering the second separate; and (H) recovering the first metal component from the first separate after step (C) by electrolytic refining.

Description

Technical Field

[0001] This invention relates to a method for separating and recovering rare earth and metal components from the waste material after firing of multilayer ceramic capacitors. Prior Technology

[0002] Multilayer ceramic capacitors (MLCCs) are expected to see significant demand as electronic components installed in automobiles, mobile phones, and other applications. A multilayer ceramic capacitor comprises: a multilayer body having an inner electrode layer and a ceramic layer; and an outer electrode. The inner electrode layer contains, for example, a metallic component such as Ni, and the ceramic layer is formed, for example, BaTiO3. Patent documents 1-4 disclose methods for recovering Ni mainly used in the inner electrode layer, and disclose methods for separating BaTiO3 contained in the ceramic layer during the Ni recovery process. [Prior Art Documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2003-253347 [Patent Document 2] Japanese Patent Application Publication No. 2003-268459 [Patent Document 3] Japanese Patent Application Publication No. 2003-277843 [Patent Document 4] Japanese Patent Application Publication No. 2003-277846 Summary of the Invention

[0004] [Problem to be Solved by the Invention] Here, the raw materials used to manufacture multilayer ceramic capacitors contain not only Ni but also rare earth elements. While patent documents 1-4 disclose the recovery of Ni, they do not disclose the recovery of rare earth elements. However, it would be ideal to recover not only metallic components such as Ni but also rare earth elements.

[0005] Therefore, the main objective of this invention is to provide a method for separating and recovering rare earth and metal components from the post-firing waste of multilayer ceramic capacitors. [Technical Means for Solving the Problem]

[0006] The method for separating and recovering rare earth and metal components from the post-firing waste of multilayer ceramic capacitors according to the present invention includes the following steps: (A) the step of preparing the post-firing waste of multilayer ceramic capacitors, wherein the post-firing waste of multilayer ceramic capacitors comprises a multilayer body including a ceramic layer and an inner electrode layer, and a sintered electrode layer disposed on the multilayer body as the outermost layer and connected to the inner electrode layer, the sintered electrode layer being the post-firing waste of the multilayer ceramic capacitor after firing, wherein the ceramic layer has an aggregate of a plurality of ceramic particles, and rare earth inclusions containing rare earth components are contained at the grain boundaries between the plurality of ceramic particles, the inner electrode layer contains a first metal component as a base metal with magnetic properties, the sintered electrode layer contains a second metal component as a noble metal without magnetic properties, and the ceramic layer, the inner electrode layer and the sintered electrode layer are sintered; (B) A step of obtaining ceramic microparticles formed by micronizing the sintered waste, rare earth inclusions, a first metal microparticle formed by micronizing the internal electrode layer, and a second metal microparticle formed by micronizing the sintered electrode layer; (C) A step of separating the sintered waste after step (B) into a first separate containing ceramic microparticles and the first metal microparticles, and a second separate containing ceramic microparticles, rare earth inclusions, and the second metal microparticles, and recovering it, using a magnet; and (H) A step of recovering the first metal component from the first separate after step (C) by electrolytic refining.

[0007] According to the present invention, rare earth components and metallic components can be separated and recovered from post-calcination waste. In particular, the first metallic component contained in the internal electrode layer can be separated and recovered as a metallic component. Furthermore, the second metallic component contained in the external electrode can be separated and recovered as a second separated product.

[0008] The method for separating and recovering rare earth and metal components from the post-firing waste of multilayer ceramic capacitors according to the present invention includes the following steps: (A) a step of preparing the post-firing waste of multilayer ceramic capacitors, wherein the post-firing waste of multilayer ceramic capacitors comprises a multilayer body including a ceramic layer and an inner electrode layer, a sintered electrode layer disposed on the multilayer body and connected to the inner electrode layer, and a sintered electrode layer disposed on the sintered electrode layer as the outermost first-stage plating layer for the multilayer ceramic capacitor after firing, wherein the ceramic layer has an aggregate of a plurality of ceramic particles, and rare earth inclusions containing rare earth components are contained at the grain boundaries between the plurality of ceramic particles, the inner electrode layer contains a first metal component as a base metal with magnetic properties, the sintered electrode layer contains a second metal component as a noble metal without magnetic properties, the first-stage plating layer contains the first metal component, and the ceramic layer, the inner electrode layer and the sintered electrode layer are sintered; (B) A step of obtaining ceramic microparticles formed by micronizing the sintered waste; a first metal microparticle formed by micronizing the rare earth inclusions, the internal electrode layer and the first stage coating layer; and a second metal microparticle formed by micronizing the sintered electrode layer; (C) A step of using a magnet to separate the sintered waste after step (B) into a first separate containing the ceramic microparticles and the first metal microparticles; and a second separate containing the ceramic microparticles, rare earth inclusions and the second metal microparticles and recovering it; and (H) A step of recovering the first metal component from the first separate after step (C) by electrolytic refining.

[0009] According to the present invention, rare earth components and metallic components can be separated and recovered from post-calcination waste. In particular, the first metallic component contained in the internal electrode layer can be separated and recovered as a metallic component. Furthermore, the second metallic component contained in the external electrode can be separated and recovered as a second separated product.

[0010] The method for separating and recovering rare earth and metal components from the post-firing waste of multilayer ceramic capacitors according to the present invention includes the following steps: (A) A step for preparing post-firing waste of multilayer ceramic capacitors, wherein the post-firing waste of multilayer ceramic capacitors comprises a multilayer body including a ceramic layer and an internal electrode layer, a sintered electrode layer disposed on the multilayer body and connected to the internal electrode layer, a first-stage plating layer disposed on the sintered electrode layer, and a second-stage plating layer disposed on the first-stage plating layer as the outermost layer, the post-firing waste of the sintered electrode layer of the multilayer ceramic capacitor, wherein the ceramic layer has an aggregate of a plurality of ceramic particles, and rare earth inclusions containing rare earth elements are contained at the grain boundaries between the plurality of ceramic particles; the internal electrode layer contains a first metal component as a base metal with magnetic properties; the sintered electrode layer contains a second metal component as a noble metal without magnetic properties; the first-stage plating layer contains the first metal component; the second-stage plating layer contains a third metal component; and the ceramic layer, the internal electrode layer, and the sintered electrode layer are sintered; (K) The step of removing at least the second stage coating from the first stage coating and the second stage coating in the post-firing waste; (B) The step of micronizing the post-firing waste from which at least the second stage coating has been removed in step (K) to obtain ceramic micronized material formed by micronizing the ceramic layer; a first metal micronized material formed by micronizing rare earth inclusions, internal electrode layer and the first stage coating; and a second metal micronized material formed by micronizing the fused electrode layer; (C) The step of separating the post-firing waste after step (B) into a first separator containing ceramic micronized material and the first metal micronized material using a magnet; and a second separator containing ceramic micronized material, rare earth inclusions and the second metal micronized material and recovering it; and (H) The step of recovering the first metal component from the first separator after step (C) by electrolytic refining.

[0011] According to the present invention, rare earth elements and metallic components can be separated and recovered from post-calcination waste. In particular, the first metallic component contained in the internal electrode layer can be separated and recovered as a metallic component. Furthermore, the second metallic component contained in the external electrode can be separated and recovered as a second separated product. [Effects of the Invention]

[0012] According to the present invention, a method for separating and recovering rare earth and metal components from the post-firing waste of multilayer ceramic capacitors can be provided.

[0013] The above-mentioned objects, other objects, features and advantages of the present invention will become more apparent from the description of the embodiments for carrying out the following invention with reference to the drawings. Simple Explanation of the Diagram

[0014] Figure 1A is a flowchart illustrating a method for separating and recovering rare earth and metallic components from waste after firing (firing for attaching electrode layers) of a multilayer ceramic capacitor according to an embodiment of the present invention. Figure 1B is a structural diagram of an electrolytic refining system. Figure 2 is a perspective view showing an example of a multilayer ceramic capacitor according to an embodiment of the present invention. Figure 3 is a cross-sectional view along line III-III of Figure 2 when the multilayer ceramic capacitor includes the attached electrode layer as the outermost layer. Figure 4 is a schematic diagram showing the state of the unfired ceramic layer and the unfired inner electrode layer in a cross-section parallel to the plane including the length direction and the stacking direction in the multilayer wafer. Figure 5 is an enlarged view of part α in Figure 3, showing the state of each layer after firing for attaching electrode layers. Figure 6 is a partial enlarged view of the ceramic layer in Figure 5. Figure 7 is a cross-sectional view (1) of a multilayer ceramic capacitor including a plating layer as the outermost layer according to an embodiment of the present invention, parallel to the plane including the length direction and the stacking direction. Figure 8 is a cross-sectional view (2) of a multilayer ceramic capacitor of another state, including a plating layer as the outermost layer, according to an embodiment of the present invention, parallel to the plane including the length direction and the stacking direction. Figure 9 is a flowchart showing a method for separating and recovering rare earth and metal components from waste material after firing (firing for attaching electrode layers) of a multilayer ceramic capacitor having a plating layer as the outermost layer, including a plating removal step. Implementation

[0015] In this embodiment, a method for separating and recovering rare earth and metallic components (first metallic component and second metallic component) from the post-firing waste of the sintered electrode layer of a multilayer ceramic capacitor is described. Furthermore, a method for separating and recovering the post-firing waste into post-firing waste of a multilayer ceramic capacitor containing the sintered electrode layer as the outermost layer, and post-firing waste of a multilayer ceramic capacitor containing a plating layer as the outermost layer on the sintered electrode layer is described. In this embodiment, firstly, a method for separating and recovering the post-firing waste of a multilayer ceramic capacitor containing the sintered electrode layer as the outermost layer is described, and secondly, a method for separating and recovering the post-firing waste of a multilayer ceramic capacitor containing a plating layer as the outermost layer on the sintered electrode layer is described. In this embodiment, the post-firing waste of the sintered electrode layer of the multilayer ceramic capacitor is sometimes referred to as post-firing waste.

[0016] 1. Firing waste of multilayer ceramic capacitors containing a sintered electrode layer as the outermost layer 1.1. Separation and recovery method of firing waste of multilayer ceramic capacitors containing a sintered electrode layer as the outermost layer The method for separating and recovering rare earth components and metal components (first metal component and second metal component) of the firing waste of multilayer ceramic capacitors containing a sintered electrode layer as the outermost layer (firing for sintering electrode layer) from embodiments of the present invention will be described.

[0017] Figure 1A is a flowchart illustrating a method for separating and recovering rare earth and metallic components from waste material after firing (firing for attaching electrode layers) of multilayer ceramic capacitors according to an embodiment of the present invention. Figure 1B is a structural diagram of an electrolytic refining system. In the separation and recovery method according to an embodiment of the present invention, waste material after firing (firing for attaching electrode layers) of multilayer ceramic capacitors is used as the starting point for separation and recovery. Here, the waste material after firing of multilayer ceramic capacitors, including the outermost layer with attached electrode layers, will be described in particular.

[0018] (1) Firing waste of multilayer ceramic capacitor containing sintered electrode layer as outermost layer Before explaining the firing waste of multilayer ceramic capacitor containing sintered electrode layer as outermost layer, the multilayer ceramic capacitor manufactured by the manufacturing steps of multilayer ceramic capacitor and its manufacturing steps will be explained first.

[0019] (1-1) Multilayer Ceramic Capacitor FIG2 is a perspective view showing an example of a multilayer ceramic capacitor according to an embodiment of the present invention. FIG3 is a cross-sectional view along line III-III of FIG2 when the multilayer ceramic capacitor includes a sintered electrode layer as the outermost layer. Here, as an example of a multilayer ceramic capacitor 10, a two-terminal multilayer ceramic capacitor will be described.

[0020] As shown in Figures 2 and 3, the multilayer ceramic capacitor 10 includes, for example, a cuboid multilayer body 12 and external electrodes 30 disposed at both ends of the multilayer body 12.

[0021] The laminate 12 has a plurality of laminated ceramic layers 14 and a plurality of internal electrode layers 16 laminated on the ceramic layers 14. Furthermore, the laminate 12 has a first main surface 12a and a second main surface 12b opposite to the height direction (lamination direction) x; a first side surface 12c and a second side surface 12d opposite to the width direction y, which is orthogonal to the height direction x; and a first end surface 12e and a second end surface 12f opposite to the length direction z, which is orthogonal to both the height direction x and the width direction y. The ceramic layers 14 and the internal electrode layers 16 are laminated along the height direction x.

[0022] The first internal electrode layer 16a and the second internal electrode layer 16b may, for example, contain a conductive material, which may include a magnetic base metal. The magnetic base metal may be an elemental metal or an alloy. Examples of magnetic base metals include Ni and Fe. Furthermore, here, metals with a higher ionization tendency than hydrogen are referred to as base metals.

[0023] The ceramic layer 14 is an aggregate of a plurality of ceramic particles (each BT in Figure 5 below, also referred to as a ceramic sintered body). Each ceramic particle can be formed, for example, by a dielectric material as the ceramic material. Such a dielectric material can be, for example, a dielectric ceramic, which is mainly composed of a perovskite-type compound containing BaTiO3, CaTiO3, SrTiO3, or CaZrO3, and has a perovskite structure. When the above-mentioned dielectric material is used as the main component, rare earth elements are added to the dielectric material as additives according to the desired characteristics of the laminate 12. Examples of the added rare earth elements include, for example, at least one of Dy, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb, and Lu. Furthermore, the above-mentioned dielectric material can also be made by adding secondary components such as Mn compounds, Fe compounds, Cr compounds, Co compounds, and Ni compounds in amounts less than the main component. Alternatively, at least one of Si, Mg, Ba, and Mn can be added as an additive to the main components mentioned above. However, since these by-products and additives may cause a decrease in the grade of rare earth components during the separation and recovery of rare earth components, these by-products and additives can be omitted.

[0024] As shown in Figures 2 and 3, the external electrode 30 is disposed on the first end face 12e side and the second end face 12f side of the laminate 12.

[0025] The external electrode 30 has 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 at least on 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 at least on the surface of the second end face 12f.

[0026] The external electrode 30 includes a sintered electrode layer 32. The first external electrode 30a includes a first sintered electrode layer 32a. The second external electrode 30b includes a second sintered electrode layer 32b. The sintered electrode layer 32 is the outermost layer of the multilayer ceramic capacitor 10. That is, the sintered electrode layer 32 is the outermost layer disposed on the multilayer body 12.

[0027] The sintered electrode layer 32 may be formed from a sintered layer comprising a glass component and a second metal component that is a non-magnetic noble metal. The second metal component of the sintered layer may, for example, comprise at least one element selected from Cu, Ag, etc. The glass component of the sintered layer may, for example, comprise an oxide containing at least one element selected from B, Si, Ba, Mg, Al, Li, etc. Furthermore, here, a metal with a lower ionization tendency than hydrogen is defined as a noble metal.

[0028] (1-2) Manufacturing method of multilayer ceramic capacitor Next, the manufacturing method of multilayer ceramic capacitor 10 will be explained.

[0029] (Step 1) First, prepare the dielectric sheet for the ceramic layer and the conductive paste for the internal electrode layer. The dielectric sheet for the ceramic layer may be formed, for example, from a dielectric paste with BaTiO3 as the main component and Dy as an additive, but is not limited to this. The conductive paste for the internal electrode layer may be formed, for example, from a Ni-based component, but is not limited to this. The dielectric sheet and the conductive paste for the internal electrode layer contain an adhesive and a solvent. The adhesive and solvent contain a resin component; for example, various known thermosetting resins such as epoxy resin, phenoxy resin, phenolic resin, polyurethane resin, and polyimide resin can be used as the resin component.

[0030] (Step 2) Then, by means of, screen printing or gravure printing, the conductive paste for the internal electrode layer is printed on the dielectric sheet in a prescribed pattern. In this way, a dielectric sheet with the pattern of the first internal electrode layer and a dielectric sheet with the pattern of the second internal electrode layer are prepared.

[0031] Furthermore, regarding dielectric sheets, dielectric sheets for outer layers without printed patterns on the internal electrode layers are also prepared.

[0032] A predetermined number of dielectric sheets for an outer layer, without the pattern of the internal electrode layer printed, are stacked. Dielectric sheets with the pattern of a first internal electrode layer printed and dielectric sheets with the pattern of a second internal electrode layer printed are sequentially stacked on this outer layer, thereby forming an inner layer portion. A predetermined number of dielectric sheets for an outer layer, without the pattern of the internal electrode layer printed, are stacked on this inner layer portion. This forms a stacked sheet having an inner layer portion and an outer layer portion. Furthermore, the dielectric sheet is sometimes referred to as the unfired ceramic layer, that is, the ceramic layer before firing the stacked wafer. The pattern of the internal electrode layer is sometimes referred to as the unfired internal electrode layer, that is, the internal electrode layer before firing the stacked wafer.

[0033] (Step 3) Next, the laminated sheet is pressed along the lamination direction using methods such as isostatic pressing to produce a laminated block.

[0034] (Step 4) Then, the laminated wafer is cut out by cutting the laminated block to a specified size. Figure 4 is a schematic diagram showing the state of the unfired ceramic layer and the unfired internal electrode layer in a cross-section parallel to the plane including the length direction and the stacking direction of the laminated wafer. Figure 4 shows a cross-sectional view of the laminated wafer before the external electrode 30 is formed. Also, the laminated wafer in Figure 4 is in the state before the degreasing in (Step 5) and the firing in (Step 6) of the laminated wafer. The resin composition contained in the laminated wafer is not shown in the figure. As shown in Figure 4, the unfired internal electrode layer 16_U and the unfired ceramic layer 14_U are alternately laminated to form the laminated wafer.

[0035] The multilayer wafer generally comprises a first metal powder (Ni_P in Figure 4), ceramic powders (BT1_P and BT2_P in Figure 4), rare earth powders (Dy_P in Figure 4), and resin components. The first metal powder mainly constitutes the unfired internal electrode layer 16_U. The ceramic powder mainly constitutes the unfired ceramic layer 14_U.

[0036] The first metal powder is, for example, an aggregate of first metal atoms that constitute the first metal component. As described above, the first metal powder may contain a conductive material, which may include a magnetic base metal. The magnetic base metal may be an elemental metal or an alloy. Examples of magnetic base metals include, for example, Ni and Fe.

[0037] Ceramic powder is an aggregate of dielectric materials. As mentioned above, examples of dielectric materials include BaTiO3, CaTiO3, SrTiO3, and CaZrO3. Furthermore, the ceramic powder comprises a first ceramic powder and a second ceramic powder. The particle size of the second ceramic powder is smaller than that of the first ceramic powder.

[0038] Rare earth powders are aggregates of rare earth atoms. As mentioned above, rare earth atoms can be categorized as at least one of the following: Dy, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb, and Lu.

[0039] The resin component is an adhesive and solvent used to generate the conductive paste for dielectric sheets and internal electrode layers. The adhesive and solvent include the resin component, and various known thermosetting resins such as epoxy resin, phenoxy resin, phenolic resin, polyurethane resin, and polyimide resin can be used as the resin component.

[0040] Figure 4 is used to further illustrate the state of the powder in the laminated wafer. The schematic diagram in Figure 4 shows the state of various powders contained in the laminated wafer before firing (step 5) and (step 6). Furthermore, the resin composition is omitted from Figure 4. As shown in Figure 4, in this embodiment, the unfired ceramic layer 14_U mainly contains the first ceramic powder (BT1_P in Figure 4). Furthermore, in the unfired ceramic layer 14_U, the first ceramic powder and the rare earth powder (Dy_P in Figure 4) are at least partially adhered to each other. As shown in the example in Figure 4, the rare earth powder is mainly adhered to the surface of the first ceramic powder, and there is essentially no chemical bonding between the rare earth powder and the interior of the first ceramic powder. Also, in this embodiment, the unfired internal electrode layer 16_U mainly contains the first metal powder (Ni_P in Figure 4). Furthermore, in the unfired internal electrode layer 16_U, the first metal powder and the second ceramic powder (BT2_P in Figure 4) are at least partially adhered to each other. As shown in the example of Figure 4, the second ceramic powder is mainly adhered to the surface of the first metal powder, and there is essentially no chemical bonding between the second ceramic powder and the interior of the first metal powder. "Adhesion" can also include partial chemical bonding between the first metal powder, ceramic powder, and rare earth powder. Moreover, a chemical bond is a bond formed by the attraction of positive and negative charges between multiple atoms, such as ionic bonds, covalent bonds, and metallic bonds.

[0041] (Step 5) Next, remove the resin components from the stacked wafer. Hereinafter, the removal of resin components in Step 5 is the degreasing process in the manufacturing process. The degreasing temperature in Step 5 is, for example, above 800°C and below 1000°C.

[0042] (Step 6) Next, the stacked body 12 is fabricated by firing the stacked wafer. The firing temperature of the stacked wafer also depends on the material of the ceramic layer or the internal electrode layer, which serves as the dielectric, but is preferably above 1000°C and below 1400°C. Steps 1 to 6 are the stacked body formation steps. Furthermore, the firing in step 6 is sometimes referred to as the firing of the stacked wafer. The stacked wafer before firing becomes the stacked body 12. Also, the internal electrode layer 16_U before firing and the ceramic layer 14_U before firing are fired to form the internal electrode layer 16 and the ceramic layer 14.

[0043] (Step 7) Next, a sintered electrode layer 32, serving as an external electrode 30, is formed by applying a paste containing a plurality of second metal powders (e.g., Cu powder) to the first and second end faces 12e and 12f of the laminate 12 and firing it. The second metal powder is, for example, an aggregate of second metal atoms that constitute a second metal component. Each second metal powder in the sintered electrode layer paste is dispersed individually or dispersed together with other powders containing other second metal powders. That is, in the sintered electrode layer paste, each second metal powder does not form chemical bonds with other second metal powders or other additives. Furthermore, by firing the sintered electrode layer paste, the second metal powders are sintered. The firing temperature of the sintered electrode layer paste is preferably 700°C or higher and 900°C or lower. Furthermore, the firing in step 7 is sometimes referred to as firing for sintered electrode layers.

[0044] Next, the state of each layer of the multilayer ceramic capacitor 10 after firing (step 7) for attaching the electrode layer will be explained. Figure 5 is an enlarged view of part α in Figure 3, and is a schematic diagram showing the state of each layer after firing for attaching the electrode layer. Figure 6 is a partial enlarged view of the ceramic layer in Figure 5. In the multilayer ceramic capacitor 10 after firing for attaching the electrode layer, the ceramic layer 14, the inner electrode layer 16, and the outer electrode 30 are all in a sintered state.

[0045] In ceramic layer 14, ceramic powder (BT1_P and BT2_P in Figure 4) is sintered, as shown in Figure 5, to form sintered ceramic particles BT (BT in Figure 5). Furthermore, ceramic powder (BT1_P and BT2_P in Figure 4) is sintered, for example, by the stacked wafer process in step 6, to form sintered ceramic particles BT. Sometimes, sintered ceramic particles BT are also referred to as sintered ceramic bodies BT. For example, through sintering, the contact between ceramic powders develops from point contact to surface contact. This leads to chemical bonding between the ceramic powders, forming an integrated ceramic particle BT (sintered ceramic body BT). Sometimes, ceramic particles BT are also formed by partial chemical bonding between ceramic powder and rare earth powder. In the example of Figure 5, ceramic layer 14 contains an aggregate of multiple ceramic particles BT. Furthermore, most of the first ceramic powder (BT1_P in Figure 4) is sintered into a ceramic layer 14 by firing, for example, the laminated wafer process (step 6). Also, most of the second ceramic powder (BT2_P in Figure 4) attached to the first metal powder (Ni_P in Figure 4) is sintered into a ceramic layer 14 by firing, for example, the laminated wafer process (step 6). At this time, most of the second ceramic powder (BT2_P in Figure 4) is not substantially bonded to the sintered internal electrode layer 16, but is extruded from the sintered internal electrode layer 16 and sintered together with the first ceramic powder to form the ceramic layer 14.

[0046] Further, the ceramic layer 14 is described, where each ceramic particle BT is formed from the core-shell 40 shown in FIG. 6. The core-shell 40 has: a core portion 42, which includes the central portion of the core-shell 40; and a shell portion 44, which covers the surface of the core portion 42. The core portion 42 is mainly formed of ceramic material. The shell portion 44 is formed by incorporating, for example, rare earth elements as additives into the ceramic material. In addition, byproducts such as Mn compounds may also be incorporated into the shell portion 44. Grain boundaries 50 exist at the boundaries between the ceramic particles BT. Rare earth inclusions are contained in the grain boundaries 50. The rare earth elements are contained in the rare earth inclusions, for example, in the form of oxides. Examples of oxides that are rare earth elements include, for example, dysprosium oxide (Dy2O3). In addition, silicon dioxide (SiO2) and manganese dioxide (MnO2) may also be contained in the rare earth inclusions. Furthermore, the core-shell structure of each ceramic particle BT has been explained above. However, each ceramic particle BT can also form a structure in which rare earth elements are incorporated into the central part of the ceramic particle BT. Moreover, ceramic particles with this structure and ceramic particles with a core-shell structure can also coexist within the ceramic layer 14.

[0047] As shown in Figure 5, the internal electrode layer 16 is formed by sintering the first metal powder (Ni_P in Figure 4) into first metal particles (Ni in Figure 5) in a sintered state. Furthermore, the first metal powder (Ni_P in Figure 4) is sintered, for example, by the multilayer wafer sintering process in (step 6), to form the sintered internal electrode layer 16. In Figure 5, Ni powder, as the first metal powder, is sintered to form Ni particles (first metal particles). Sometimes, the first metal particles in a sintered state are also referred to as a first metal sintered body. For example, the first metal powder is heated during sintering, thereby developing the contact between the first metal powders from point contact to surface contact. This leads to bonding between the first metal powders, forming an integrated first metal particle (first metal sintered body). In the example of Figure 5, the internal electrode layer 16 comprises an aggregate of multiple first metal particles.

[0048] As shown in Figure 5, a second metal powder (e.g., Cu powder) is sintered through a sintered electrode layer 32 (external electrode 30), forming second metal particles (Cu in Figure 5) in a sintered state. In Figure 5, Cu powder, serving as the second metal powder, is sintered to form Cu particles (second metal particles). Sometimes, the second metal particles in a sintered state are also referred to as a second metal sintered body. For example, the second metal powder is heated during sintering through a sintered electrode layer, thereby developing the contact between the second metal powders from point contact to surface contact. This allows bonding between the second metal powders to form an integrated second metal particle (second metal sintered body). In the example of Figure 5, the sintered electrode layer 32 comprises an aggregate of multiple second metal particles.

[0049] Multilayer ceramic capacitor 10 is manufactured through the above manufacturing steps.

[0050] Here, when the multilayer ceramic capacitor 10 is manufactured by the above-described manufacturing method, the waste material after firing in this embodiment is the waste material after firing the electrode layer in step 7.

[0051] (2) Separation and Recycling Method Flowchart Referring to FIG1A, the flowchart of the separation and recycling method for the waste after firing of a multilayer ceramic capacitor comprising a sintered electrode layer as the outermost layer according to the present invention will be described. The separation and recycling method in FIG1A includes: a common separation and recycling route, a separation and recycling route for rare earth components, a separation and recycling route for a first metal component, and a separation and recycling route for a second metal component. The separation and recycling routes for rare earth components and the first metal component branch off from the common separation and recycling route. The separation and recycling route for the second metal component branch off from the separation and recycling route for rare earth components.

[0052] Common separation and recovery routes include, for example, the preparation of post-calcination waste in step (A), the micronization in step (B), and the magnetic separation in step (C). After the magnetic separation in step (C), the route branches into a separation and recovery route for rare earth components and a separation and recovery route for the first metal component. The separation and recovery route for rare earth components may include, for example, the dissolution of the second separated product in step (D), and further includes the filtration in step (F) and the neutralization in step (G). Furthermore, after the filtration in step (F), the separation and recovery route for the second metal component branches off from the separation and recovery route for rare earth components. The separation and recovery route for the second metal component may include, for example, the dissolution of undissolved material in step (E), and further includes the filtration in step (J). The separation and recovery route for the first metal component may include, for example, the electrolytic refining of the first separated product in step (H), and further includes various treatments in step (I).

[0053] (Step (A): Preparation of Post-Firing Waste) In step (A), post-firing waste (for firing the attached electrode layer) of the multilayer ceramic capacitor is prepared. The post-firing waste is as described above. The post-firing waste includes: a multilayer body 12 containing a ceramic layer 14 and an internal electrode layer 16, and an attached electrode layer 32. The ceramic layer 14, the internal electrode layer 16, and the attached electrode layer 32 are in a sintered state.

[0054] (Step (B): Miniaturization) In step (B), the post-firing waste is miniaturized. For example, it can be miniaturized by pulverizing the post-firing waste, but it is not limited to this. Pulverization can be carried out by applying a pulverizing force generated by vibration to the object using a vibratory mill, grinding the object, applying a pulverizing force generated by impact to the object, etc., but it is not limited to these methods. In the magnetic separation in step (C) below, it is preferable to miniaturize the post-firing waste to a degree that makes it easy to separate. By miniaturizing the post-firing waste, ceramic miniaturized material formed by miniaturizing the sintered ceramic layer 14, rare earth inclusions in the sintered state, a first metal miniaturized material formed by miniaturizing the sintered internal electrode layer 16, and a second metal miniaturized material formed by miniaturizing the sintered sintered electrode layer 32. Ceramic micronized materials may include, for example, ceramic materials such as BaTiO3, CaTiO3, SrTiO3, or CaZrO3. Rare earth elements may include, for example, dysprosium oxide (Dy2O3), and may also include, for example, silicon dioxide (SiO2) and manganese dioxide (MnO2). First metal micronized materials may include, for example, first metal components such as Ni and Fe. Second metal micronized materials may include, for example, second metal components such as Cu. The average particle size of the sintered waste after micronization is not limited. The average particle size can be determined, for example, using a sieve.

[0055] (Step (C): Magnetic Separation) In step (C): magnetic separation, a magnet is used to perform magnetic separation on the calcined waste that has been miniaturized in step (B). That is, by magnetic separation, the calcined waste is separated into a first separate and a second separate and recycled.

[0056] The first separated product comprises a first metal micronized material (Ni in Figure 1A) and a ceramic micronized material (BT in Figure 1A). The first metal micronized material contains a first metallic component that is a magnetic base metal. On the other hand, the ceramic micronized material is not magnetic. By magnetic separation, the first separated product is separated into magnetic materials. Specifically, in the first separated product, when the magnetic first metal micronized material is separated into magnetic materials, the non-magnetic ceramic micronized material is entrained within the first metal micronized material.

[0057] The second separated product comprises a second metal micronized compound (Cu in Figure 1A), a rare earth inclusion (Dy₂O₃ in Figure 1A), and a ceramic micronized compound (BT in Figure 1A). The second metal micronized compound contains a second metal component that is a non-magnetic noble metal. Furthermore, the rare earth inclusion and the ceramic micronized compound are non-magnetic. Therefore, by magnetic separation, the second metal micronized compound, the rare earth inclusion, and the ceramic micronized compound are separated into non-magnetic substances.

[0058] Therefore, through this magnetic separation, the second separated material can be removed from the post-firing waste, and the first separated material containing the first metal micronized material can be separated and recovered as the first metal component. For example, the first metal micronized material is formed by micronizing Ni (the first metal component) in a sintered state that constitutes the internal electrode layer 16. Furthermore, in this invention, the separation and recovery of the first metal component includes not only the separation and recovery of the first metal component itself, but also the separation and recovery of the first separated material containing the first metal micronized material as the first metal component.

[0059] Furthermore, the first metallic component includes the first metal atom itself, reactants obtained from the chemical reaction of the first metal atom with other atoms (i.e., compounds of the first metallic component), solutions of the first metal atom, and solutions of compounds of the first metallic component. Also, the state of the first metallic component can be any one of a liquid state, a solid state, or a mixture of liquid and solid. Furthermore, the first metallic component can be any one of an amorphous state, a crystalline state, or a mixture of amorphous and crystalline states.

[0060] In other words, through this magnetic separation, the second metal micro-components and rare earth elements obtained from the removal of the first separator from the post-calcination waste can be separated and recovered.

[0061] Furthermore, in the magnetic separation process, it is preferable to mix and disperse the micronized calcined waste with water or other aqueous solvents in step (B) to form a mixed state, and then use a magnet for separation.

[0062] If the refined post-firing waste is mixed with an aqueous solvent to form a slurry, a state in which the ceramic microparticles, rare earth elements, first metal microparticles, and second metal microparticles contained in the refined post-firing waste are dispersed can be achieved. Therefore, in step (C), the first and second separated components can be easily separated using a magnet. If the refined post-firing waste is in a dry state, the first and second separated components tend to be less dispersed than in the slurry state. Therefore, for example, when the first separated component is attracted by a magnet, the second separated component may be trapped within the first separated component and attracted by the magnet, sometimes making it difficult to separate the first and second separated components.

[0063] (Step (D): Dissolution of the Second Separate) In step (D), the second separate product recovered in step (C) is dissolved in an inorganic acid that does not have oxidizing power. This generates a solution containing rare earth components, specifically the rare earth components contained in the second separate product. Therefore, the solution containing rare earth components can be separated and recovered as the rare earth components. At this time, the ceramic micro-particles and the second metal micro-particles in the second separate product will precipitate. The ceramic micro-particles react with the inorganic acid that does not have oxidizing power, thereby forming undissolved matter and precipitating. Furthermore, the second metal micro-particles, such as Cu, are insoluble in the inorganic acid because their ionization tendency is less than that of the hydrogen ions contained in the inorganic acid that does not have oxidizing power. The inorganic acid that does not have oxidizing power is, for example, selected from at least one group including dilute sulfuric acid and hydrochloric acid.

[0064] Furthermore, as described above, rare earth components are separated and recovered as solutions containing rare earth components. In this 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 solutions containing rare earth components as rare earth components. That is, rare earth components include rare earth atoms themselves, reactants obtained from the chemical reaction of rare earth atoms with other atoms (i.e., rare earth component compounds), solutions of rare earth atoms, and solutions of rare earth component compounds. Moreover, the rare earth components can be in any of the following states: liquid, solid, or a mixture of liquid and solid. Furthermore, the rare earth components can be in any of the following states: amorphous, crystalline, or a mixture of amorphous and crystalline states.

[0065] In step (D), it is preferable to adjust the pH of the solution containing rare earth components to above 1.5 and below 2.5 by adding an inorganic acid that does not have oxidizing power.

[0066] In step (D), the pH of the solution containing rare earth components is adjusted to a value between 1.5 and 2.5 using a non-oxidizing inorganic acid. This primarily dissolves the rare earth components in the rare earth-containing material within the non-oxidizing inorganic acid. Furthermore, if the pH is adjusted to a level stronger than the aforementioned range, ceramic microparticles may sometimes dissolve in the non-oxidizing inorganic acid; therefore, it is preferable to adjust the pH to the aforementioned range. More preferably, the pH of the solution containing rare earth components is adjusted to 2 by adding a non-oxidizing inorganic acid.

[0067] Furthermore, in step (C), when magnetic separation is performed on the post-calcination waste in a slurry state, the separated second precipitate is in a slurry state with a pH of approximately 7. By adding a non-oxidizing inorganic acid to this slurry, a solution containing rare earth elements with a pH adjusted to above 1.5 and below 2.5 can also be generated. The second precipitate after magnetic separation does not need to be in a slurry state; it can also be in a dry state.

[0068] When the ceramic microparticles contained in the second fraction are, for example, BaTiO3, and are non-oxidizing inorganic acids, dilute sulfuric acid is preferable. When dilute sulfuric acid is used, insoluble BaSO4 forms on the surface of the BaTiO3 ceramic microparticles, causing them to precipitate. Furthermore, second metal microparticles such as Cu have a lower ionization tendency than the hydrogen ions contained in non-oxidizing inorganic acids, and are therefore insoluble in them. On the other hand, rare earth powders are soluble in dilute sulfuric acid. Specifically, for example, if the second fraction containing second metal microparticles of Cu, rare earth components such as Dy2O3, and ceramic microparticles mainly composed of BaTiO3 are dissolved in dilute sulfuric acid, BaTiO3 will precipitate, and Cu will not dissolve. Alternatively, a solution of dysprosium sulfate (Dy2(SO4)3) in dilute sulfuric acid, containing Dy from the rare earth components, can be generated as a solution containing rare earth components.

[0069] Furthermore, as mentioned above, hydrochloric acid, other than dilute sulfuric acid, can be used as an inorganic acid that does not have oxidizing power. However, when hydrochloric acid is used as an inorganic acid that does not have oxidizing power, soluble BaCl2 is formed on the surface of BaTiO3, which is a ceramic microstructure. Therefore, it is preferable to adjust the pH value of hydrochloric acid or the like with high precision so that the ceramic microstructure precipitates and the rare earth inclusions dissolve in a state where the second metal microstructure is insoluble.

[0070] (Step (F): Filtration) In step (F), the solution containing rare earth elements generated in step (D), which includes the precipitated ceramic microparticles and undissolved second metal microparticles, is filtered to perform solid-liquid separation between the undissolved ceramic microparticles and second metal microparticles and the solution containing rare earth elements. Through this solid-liquid separation, the solution containing rare earth elements after removing the undissolved ceramic microparticles and second metal microparticles can be separated and recovered as the rare earth elements from the solution containing the undissolved ceramic microparticles and second metal microparticles.

[0071] For example, suppose that in step (D), under the condition that BaTiO3 is precipitated and the second metal micro-alloys such as Cu are not dissolved, a solution of dysprosium sulfate (Dy2(SO4)3) dissolved in dilute sulfuric acid is generated as a solution containing rare earth components. In this case, by means of filtration in step (F), the dysprosium sulfate solution after removing BaTiO3 and Cu can be separated and recovered as a rare earth component.

[0072] Filtration can be performed using filter paper (filter cloth). The mesh size of the filter paper (filter cloth) should ideally be such that undissolved ceramic microparticles and second metal microparticles do not pass through the filter paper (filter cloth).

[0073] Any solution containing rare earth elements, including undissolved ceramic microparticles and second metal microparticles, generated in step (D) can be subjected to solid-liquid separation. It is not limited to solid-liquid separation using filtration; any known method such as self-decantation or centrifugation can be appropriately selected for solid-liquid separation. Furthermore, filtration is preferred.

[0074] (Step (G): Neutralization) In step (G), the rare earth-containing solution obtained in step (F) is neutralized, causing the rare earth components to precipitate and be recovered. The precipitated rare earth components are separated and recovered, for example, by filtering the neutralized solution containing rare earth components. At this time, the rare earth components are separated and recovered as rare earth compound (e.g., Dy(OH)3). In this 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 reactants obtained from the chemical reaction of the rare earth components, i.e., rare earth compound, as rare earth components.

[0075] Neutralization systems use alkalis. Examples of alkalis include sodium hydroxide and potassium hydroxide. If the redox potential changes, the pH range of rare earth component precipitation may change, but by using these as alkalis, the pH range of rare earth component precipitation can be stabilized.

[0076] Furthermore, in step (G), the rare earth components are recovered by adjusting the pH of the solution containing rare earth components to a value above 6 and below 9. This allows for the efficient separation and recovery of the precipitate produced by the neutralization reaction as rare earth components. More preferably, the pH of the solution containing rare earth components is adjusted to 8 by adding an alkali.

[0077] For example, in the filtration process of step (F), when obtaining a dysprosium sulfate solution after the removal of BaTiO3 and Cu, 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 can cause dysprosium, as a rare earth component, to precipitate as dysprosium hydroxide (Dy(OH)3), thereby achieving separation and recovery. Here, dysprosium hydroxide (Dy(OH)3) can be separated and recovered by filtering the solution obtained from neutralizing the dysprosium sulfate solution with an alkali. In addition to filtration, known methods such as decantation and centrifugation can also be used.

[0078] Furthermore, during the magnetic separation in step (C), metallic components (so-called contaminants) are present that are not separated into the first precipitate but are carried over to the second precipitate. Therefore, the solution containing rare earth elements generated during the dissolution of the second precipitate in step (D) sometimes contains metallic components as contaminants. These metallic components are, for example, Ti, Mn, Ni, etc. In step (G), an alkali is added to the solution containing rare earth elements, for example, to adjust the pH to a value between 3 and 5, preferably about 4, thereby separating and recovering Ti and Mn. In this case, Ti precipitates, for example, as Ti(OH)4, and Mn precipitates, for example, as Mn(OH)2. Therefore, the solution containing rare earth elements adjusted to about pH 4 is filtered, and Ti(OH)4 and Mn(OH)2 are recovered.

[0079] Subsequently, an alkali is added to the solution containing rare earth components obtained by separating Ti and Mn, and the pH is adjusted to a value of 6 or higher and 9 or lower, preferably about 8, as described above, so as to separate and recover the rare earth components.

[0080] Subsequently, an alkali is added to the solution obtained by separating Ti, Mn, and rare earth components, for example, to adjust the pH value to a value greater than 9 and less than 11, preferably about 10, thereby separating and recovering Ni, etc. In this case, Ni precipitates, for example, in the form of Ni(OH)2. The solution adjusted to about 1 pH value is filtered, and Ni(OH)2, etc., is recovered.

[0081] By repeatedly performing phased neutralization and filtration, various components (pollutants and rare earth components, etc.) contained in the solution containing rare earth elements can be separated and recovered.

[0082] Furthermore, in the staged neutralization of the solution containing rare earth elements as described above, before separating the rare earth elements, the solution is neutralized to a pH value of 3 or higher and a pH value of 5 or lower, preferably around pH 4. Therefore, contaminants such as Ti and Mn can be removed from the solution containing rare earth elements first. Since Ti and Mn are removed from the solution in this way, using the solution containing rare earth elements after removing these contaminants makes it easier to separate the rare earth elements.

[0083] (Step (E): Dissolution of Undissolved Substances) In step (E), the ceramic microparticles and the second metal microparticles obtained by filtration in step (F) are dissolved in ammonia water. This generates a second metal solution containing the second metal component contained in the second metal microparticles. Therefore, the second metal solution can be separated and recovered as the second metal component. At this time, the ceramic microparticles will precipitate.

[0084] Specifically, a second metal micronized compound containing a second metal component such as Cu and a ceramic micronized compound as BaTiO3 are dissolved in ammonia water. This yields a second metal solution containing, for example, a copper-ammonia complex such as [Cu(NH3)4]2+. BaTiO3 precipitates in the second metal solution.

[0085] Furthermore, as described above, the second metal component is separated and recovered as a second metal solution. In this invention, the separation and recovery of the second metal component includes not only the separation and recovery of the second metal component itself, but also the separation and recovery of the second metal component solution as the second metal component. Here, the second metal component includes the second metal component itself, reactants obtained from the chemical reaction of the second metal component with other atoms, i.e., a second metal component compound, a solution of the second metal component, a solution of the second metal component compound, etc. Furthermore, the state of the second metal component can be any one of a liquid state, a solid state, or a mixture of liquid and solid. Also, the second metal component can be any one of an amorphous state, a crystalline state, or a mixture of amorphous and crystalline states.

[0086] In step (E), it is preferable to adjust the pH of the second metal solution to above 9 and below 10 by adding ammonia. By adjusting the pH of the second metal solution to above 9 and below 10 in step (E), the second metal solution can be efficiently separated and recovered as the second metal component. More preferably, the pH of the second metal solution is adjusted to 9.5 by adding ammonia.

[0087] Furthermore, when dissolving the undissolved ceramic microparticles and second metal microparticles taken out in step (F) in ammonia water, it is preferable to add an ammonium salt, such as ammonium sulfate, to the ammonia water. Here, the ammonia water serves as the ammonia supply source to form copper-ammonia complexes and other ammonia complexes, such as copper-ammonia complexes. The ammonium salt provides counterions for these ammonia complexes. For example, ammonium sulfate provides SO4 2- as a counterion for the copper-ammonia complex [Cu(NH3)4]2+. Even when the ammonia concentration decreases, salts such as CuSO4 are formed, thereby inhibiting the precipitation of Cu ions.

[0088] (Step (J): Filtration) In step (J), the second metal solution containing the precipitated ceramic microparticles generated in step (E) is filtered to separate the precipitated ceramic microparticles from the second metal solution. Through this solid-liquid separation, the second metal solution after removing the precipitated ceramic microparticles from the second metal solution containing the precipitated ceramic microparticles can be separated and recovered as the second metal component.

[0089] For example, in step (E), assuming that a second metal solution is generated in the state of BaTiO3 precipitation, consisting of a second metal component such as Cu dissolved in ammonia water, is used as the second metal solution. The second metal solution contains, for example, copper-ammonia complexes such as [Cu(NH3)4]2+. In this case, by means of filtration in step (J), the second metal solution containing copper-ammonia complexes after the removal of BaTiO3 can be separated and recovered as the second metal component.

[0090] Filtration can be performed using filter paper (filter cloth). The mesh size of the filter paper (filter cloth) is preferably such that the precipitated ceramic microparticles will not pass through the filter paper (filter cloth). Furthermore, solid-liquid separation can be performed on the second metal solution containing the precipitated ceramic microparticles generated in step (E), and it is not limited to solid-liquid separation using filtration. Known methods such as self-decantation and centrifugation can be appropriately selected for solid-liquid separation. Filtration is preferred.

[0091] (Step (H): Electrolytic Refining) In step (H), the first separated product recovered in step (C) is added to electrolyte 61a (Fig. 1B) and electrolytically refined to recover the first metal component from the first separated product. The first separated product includes: a first metal micronization containing the first metal component; and a ceramic micronization containing ceramic material. For example, electrolytic refining is performed using the electrolytic refining system 60 shown in Fig. 1B. Fig. 1B is a structural 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 electrolyte 61a, and the anode 62 and cathode 63 are installed in the electrolytic cell 61 by immersion in the electrolyte 61a. The anode basket 65 is capable of accommodating the first separated product 65a, and is integrally formed with the anode 62. The anode basket 65 is immersed in the electrolyte 61a and is configured to allow ions of the first metal component of the first metal micronization in the first separated product to pass through. The power source 64 applies electricity between the anode 62 and the cathode 63.

[0092] By applying a specified voltage to power supply 64, the first metal component of the first metal micronized compound contained in the first separator 65 is ionized. The ionized first metal component in anode 62 reaches cathode 63. Ions of the first metal component are deposited on the surface of cathode 63. Thus, the first metal component of the first metal micronized compound can be separated and recovered from the first separator by electrolytic refining. Furthermore, the components in the first separator other than the first metal component, mainly ceramic micronized compounds, will precipitate.

[0093] For example, when the first metal component of the first metal micronized compound is Ni (Ni in Figure 1B), the reaction Ni + 2e- → Ni2+ occurs in the anode 62. On the other hand, the reaction Ni2++ 2e- → Ni occurs in the cathode 63, allowing Ni to precipitate on the surface of the cathode 63 and be separated and recovered. Furthermore, the components in the first separated product other than the first metal component, mainly ceramic micronized compound (BT2 in Figure 7B), will precipitate.

[0094] When recovering the first metallic component from the first separated product through electrolytic refining, almost no hydrogen is generated when the first metallic component of the first metallic micronized product is ionized. Therefore, according to electrolytic refining, explosions caused by the combination of hydrogen and oxygen can be suppressed, thereby allowing for safe separation and recovery. Furthermore, electrolytic refining allows the first metallic component to be extracted onto the electrode, thus enabling the recovery of a relatively high purity of the first metallic component.

[0095] Furthermore, as long as electrolytic refining can be performed by flowing an electric current through the metal powder containing the object being processed 65a, the design perspective can be either the electrolytic refining system 60 or the first separated product of the object being processed 65a. When designing the electrolytic refining system 60, a configuration is considered where a magnet and electrodes are combined, and the metal powder is in close contact with the electrodes when energized. In this case, the metal powder containing the object being processed 65a does not need to be processed into the block described below.

[0096] In this embodiment, the first separator, which is the object to be processed 65a, includes a first metal microparticle and a ceramic microparticle. If the first metal microparticle is dispersed in the first separator, even if a voltage is applied from the anode 62, current is difficult to flow through the entire first metal microparticle in the anode basket 65, thus making it difficult to ionize the entire first metal microparticle. As described above, by pre-treating the first separator into a block of metal powder in contact with each other to the extent that current flows, the degree of contact between the first metal microparticles in the first separator can be improved. Therefore, it is easier for current to flow through the entire first metal microparticle in the anode basket 65, and easier to ionize the entire first metal microparticle. It is preferable to form the block in which the proportion of the first metal microparticle in the first separator is 60 wt% or more, more preferably 80 wt% or more, and even more preferably 90 wt% or more, thereby making it easier for current to flow through the first metal microparticle.

[0097] When designing the first separated component 65a as the object of processing, it is considered to process it into a block in which metal powder comes into contact with the flow of electric current. Methods for processing the first separated component into a block include, for example, compressing the first separated component to form a tight seal, heat-treating the first separated component by partially melting the metal powder with heat to form a tight seal, and combinations thereof. The heat treatment temperature is, for example, 600°C or higher, preferably 800°C or higher, and more preferably 1200°C or higher. During compression, it is preferable to compress to the degree to which the metal powder undergoes plastic deformation. In other words, it is preferable to compress to the level of the yield stress of the metal powder. Furthermore, a binder can be added to the first separated component during the block forming process. As a binder, there are no limitations as long as it can form the first separated component into a block; for example, PVA can be used. Furthermore, when using adhesives with good pyrolytic properties, they are less likely to dissolve into wastewater because they will burn during heat treatment, which is better from an environmental point of view.

[0098] In the above, by electrolytically refining the first separator contained in the anode basket 65, the metal composition is extracted from the surface of the cathode 63. However, depending on the type of the first metal composition, by electrolytically refining, for example, the first separator contained in a cathode basket not shown, the first metal composition can be extracted from the surface of the anode 62.

[0099] (Step (I): Various Processing Methods) In step (I), by processing the first metal component recovered in step (H), the first metal component can be separated and recovered as a desired first metal component compound. For example, by generating a first metal solution that reacts with the first metal component solution recovered in step (H), the first metal component can be separated and recovered as a desired first metal component compound. For example, when the first metal component is Ni, by reacting with sulfuric acid and hydrochloric acid, the first metal component can be separated and recovered as first metal component compounds such as NiSO4 and NiCl2. In this invention, the separation and recovery of the first metal component includes not only the separation and recovery of the first metal component itself, but also the separation and recovery of the reactants obtained from the chemical reaction of the first metal component, i.e., the first metal component compound, as the first metal component.

[0100] (3) Effects According to the above separation and recovery method, the first metal component constituting the inner electrode layer 16, the second metal component constituting the outer electrode 30, and the rare earth components contained in the ceramic layer 14 can be separated and recovered from the waste after firing of the multilayer ceramic capacitor. The specific explanation is as follows.

[0101] The inventors of this case considered effectively utilizing the various components contained in the waste material after firing (firing for attaching electrode layers) of multilayer ceramic capacitors. In the waste material after firing, various components are in a sintered state. For example, the inner electrode layer is formed by firing and sintering first metal particles (first metal sintered body) containing first metal powder such as Ni. Similarly, the ceramic layer is formed by firing and sintering ceramic particles (ceramic sintered body) containing ceramic powder such as BaTiO3. Furthermore, the outer electrode is formed by firing and sintering second metal particles (second metal sintered body) containing second metal powder such as Cu. It was discovered that even in such a sintered state of the multilayer ceramic capacitor, by designing a separation and recovery method, the various components contained in the multilayer ceramic capacitor can be separated and recovered.

[0102] Furthermore, in step (B), by micronizing the post-firing waste, ceramic microparticles, rare earth inclusions, a first metal microparticle, and a second metal microparticle can be obtained. In step (C), by using a magnet to separate the micronized post-firing waste, it can be separated into a first separate and a second separate. The first separate contains ceramic microparticles and a first metal microparticle. The second separate contains ceramic microparticles, rare earth inclusions, and a second metal microparticle. Therefore, through step (C), by separating and recovering the first separate, the second separate can be removed from the post-firing waste, and the first separate containing the first metal microparticle can be separated and recovered as the first metal component.

[0103] Subsequently, by dissolving the second separated product in a non-oxidizing inorganic acid in step (D), a solution containing rare earth components, specifically rare earth components from the rare earth powder, is generated. This allows for the separation and recovery of the rare earth component solution. At this point, the ceramic micro-alloys and second metal micro-alloys in the second separated product will precipitate. The ceramic micro-alloys react with the non-oxidizing inorganic acid, forming undissolved matter that precipitates. Furthermore, the second metal micro-alloys, such as Cu, are insoluble in the non-oxidizing inorganic acid because their ionization tendency is lower than that of the hydrogen ions contained in the non-oxidizing inorganic acid.

[0104] Subsequently, by dissolving the ceramic microparticles and the second metal microparticles from the second separator obtained in step (D) in ammonia water, a second metal solution containing the second metal component such as Cu dissolved in the second metal microparticles can be generated. This allows the second metal solution to be separated and recovered as the second metal component. At this point, the ceramic microparticles in the second separator are insoluble in ammonia water and precipitate.

[0105] By employing a separation and recovery method comprising steps (C), (D), and (E), rare earth elements can be separated and recovered from the micronized post-calcination waste as a solution containing rare earth elements, and a second metal solution can also be separated and recovered as a second metal component. Furthermore, during each step, the proportion of rare earth elements in the material containing rare earth elements and the proportion of the second metal component in the material containing the second metal component increase. Therefore, it is possible to recover rare earth elements such as Dy and second metal components such as Cu at high grades.

[0106] Furthermore, the separation and recovery method in Figure 1A further includes step (H). In step (H), the first metal component can be separated and recovered from the first separator by electrolytic refining. Moreover, by using electrolytic refining, almost no hydrogen is generated when the first metal component of the first metal micronized material is ionized, allowing for the safe recovery of the first metal component. Furthermore, by using electrolytic refining, a relatively high purity of the first metal component can be recovered. Furthermore, in step (H), the ceramic micronized material contained in the first separator precipitates in the electrolyte 61a, thus separating the ceramic micronized material contained in the first separator from the first metal component.

[0107] Therefore, by employing a separation and recovery method including steps (C) and (H), the first metal component can be separated and recovered from the miniaturized post-calcination waste. Furthermore, the proportion of the first metal component in the material containing the first metal component increases during each step. Thus, it is possible to recover first metal components such as Ni at high grades.

[0108] As described above, by utilizing the waste from the firing of multilayer ceramic capacitors to separate and recover the first metal component, the second metal component, and rare earth components, the waste can be used as a resource instead of being discarded as waste, thereby reducing the environmental impact.

[0109] 1.2. Experimental Examples The following examples illustrate the recovery of metal and rare earth components from waste after self-calcination.

[0110] [Example] 10 g of post-firing waste was prepared. The 10 g of post-firing waste contained 35% by mass (3.5 g) Ni as the first metal component, 7% by mass (0.7 g) Cu as the second metal component, 54% by mass (5.4 g) BaTiO3 ceramic particles (ceramic sintered body), 2% by mass (0.2 g) Dy as a rare earth component, and 2% by mass (0.2 g) contaminants such as Mg, Mn, and SiO2 (step (A)). The post-firing waste was pulverized to make it fine (step (B)). The finely pulverized post-firing waste was mixed with 100 ml of water to make a slurry. The slurry was separated using a magnet. By magnetic separation, 4.5 g of the first separator and 4.6 g of the second separator were separated and recovered (step (C)). Subsequently, 100 ml of water was added to 4.6 g of the second fraction, and the pH was adjusted to 2 by gradually adding 1 mol% sulfuric acid. This precipitated the ceramic micro-components (BaTiO3) and the second metallic micro-components (Cu) in the second fraction, dissolving the Dy contained in the rare earth elements in the sulfuric acid solution (step (D)). The solution containing the precipitated ceramic micro-components (BaTiO3) and the second metallic micro-components (Cu) with Dy dissolved in the sulfuric acid solution was filtered to obtain 90 ml of dysprosium sulfate (Dy2(SO4)3) solution (step (F)). A small amount of 1 mol% sodium hydroxide solution was gradually added to the 90 ml of dysprosium sulfate solution as a base to adjust the pH to 8 (step (G)). The solution was filtered to separate and recover 0.1 g of Dy(OH)3. Therefore, through this step, approximately 40% of the Dy contained in the incineration waste can be recovered.

[0111] Furthermore, 100 ml of water and 2 g of ammonium sulfate were added to 4.1 g of the filtrate containing the ceramic micronization (BaTiO3) and the second metal micronization (Cu) recovered in step (F), and the pH was adjusted to 9.5 by gradually adding small amounts of 1 mol% ammonia. This caused the ceramic micronization (BaTiO3) to precipitate, and the second metal micronization (Cu) to dissolve in the ammonia (step (E)). The solution was then filtered to separate and recover 90 ml of the copper-ammonia complex [Cu(NH3)4]2+. Therefore, through this step, approximately 60% of the Cu contained in the calcined waste was recovered.

[0112] Furthermore, 4.5 g of the metal powder containing mainly BaTiO3 attached to Ni recovered in step (C) was heat-treated to obtain a metal block. This metal block was placed in an anode basket 65, with the cathode positioned on the opposite electrode, and electrolytic refining was performed by applying the current required to deposit 1.0 g of nickel metal onto the cathode (step (H)). The nickel metal deposited on the anode was stripped off, and 0.9 g of metallic nickel was separated and recovered. The 0.9 g of metallic nickel solution was dissolved in 9 ml of sulfuric acid to obtain a nickel sulfate solution (step (I)).

[0113] [Experimental Results] As can be seen from the above experiments, according to the separation and recycling method in Figure 1A, using the waste material after firing of multilayer ceramic capacitors as the starting material, and then through magnetic separation and electrolytic refining steps, high-grade rare earth components such as Dy, Ni and Cu, the first metal component and the second metal component can be easily separated and refined.

[0114] 2. Post-firing waste of multilayer ceramic capacitors with a plating layer as the outermost layer on the sintered electrode layer 2.1. Separation and recycling method of post-firing waste of multilayer ceramic capacitors with a plating layer as the outermost layer on the sintered electrode layer In the multilayer ceramic capacitor 10 with a sintered electrode layer as the outermost layer described above, the outer electrode 30 includes a sintered electrode layer 32. Furthermore, the sintered electrode layer 32 is the outermost layer of the multilayer ceramic capacitor 10 (Fig. 3). However, the form of the outer electrode 30 is not limited to this. The outer electrode 30 may include both the sintered electrode layer 32 and a plating layer. Furthermore, the plating layer is the outermost layer of the multilayer ceramic capacitor. The following describes a method for separating and recycling post-firing waste of such multilayer ceramic capacitors with a plating layer as the outermost layer on the sintered electrode layer. Descriptions identical to those for the method of separating and recycling post-firing waste of multilayer ceramic capacitors with a sintered electrode layer as the outermost layer are omitted or simplified.

[0115] Figure 7 is a cross-sectional view (1) of a multilayer ceramic capacitor including a plating layer as the outermost layer according to an embodiment of the present invention, parallel to the plane including the length direction and the stacking direction. Figure 8 is a cross-sectional view (2) of another type of multilayer ceramic capacitor including a plating layer as the outermost layer according to an embodiment of the present invention, parallel to the plane including the length direction and the stacking direction.

[0116] Multilayer ceramic capacitors 10A (FIG. 7) and 10B (FIG. 8), which include a plating layer as the outermost layer, comprise a multilayer body 12 and, further, an external electrode 30 disposed on the multilayer body 12. The external electrode 30 comprises a sintered electrode layer 32 and a plating layer 34 disposed on the sintered electrode layer 32. The plating layer 34 is the outermost layer of the multilayer ceramic capacitors 10A and 10B. The configuration, except for the plating layer 34, is the same as that of the multilayer ceramic capacitor 10, which includes a sintered electrode layer 32 as the outermost layer. The plating layer 34 is formed, for example, by comprising at least one material selected from Ni, Sn, Cu, Ag, etc. Furthermore, the multilayer ceramic capacitor 10, which includes a sintered electrode layer 32 as the outermost layer, does not contain a plating layer (FIG. 3).

[0117] Multilayer ceramic capacitors 10A and 10B are formed after steps (1) to (7) of the multilayer ceramic capacitor 10, by step (8) of depositing a plating layer 34 onto the sintered electrode layer 32. In step (8), a first plating layer 34a (first lower plating layer 34a1, first upper plating layer 34a2) is formed on the first sintered electrode layer 32a by performing a plating process, and a second plating layer 34b (second lower plating layer 34b1, second upper plating layer 34b2) is formed on the second sintered electrode layer 32b. The plating layer 34 is formed, for example, by barrel plating. During the plating process, either electrolytic plating or electroless plating can be used. However, electroless plating requires pretreatment with a catalyst or the like to increase the plating deposition rate, which has the disadvantage of complicated procedures. Therefore, electroplating is generally preferred.

[0118] Multilayer ceramic capacitors 10A and 10B, with a plating layer 34 as their outermost layer, are also included in the waste after firing (firing for the sintered electrode layer) in the same way as multilayer ceramic capacitor 10, with a sintered electrode layer 32 as its outermost layer (sometimes referred to as multilayer ceramic capacitor 10 without plating layer 34). Furthermore, depending on the material constituting the plating layer 34, multilayer ceramic capacitors 10A and 10B with plating layer 34 may be incorporated into the separation and recycling method shown in FIG. 1A above, or into the separation and recycling method shown in FIG. 9 below. The separation and recycling method in FIG. 1A does not include the step of removing the plating layer 34, while the separation and recycling method in FIG. 9 includes the step of removing the plating layer 34 (step (K)).

[0119] Furthermore, the plating layer 34 can be formed from a single plating layer (Fig. 7), or it can be formed by stacking multiple plating layers (Fig. 8). The following describes a multilayer ceramic capacitor 10A with a single plating layer 34 and a multilayer ceramic capacitor 10B with multiple plating layers 34. Furthermore, for multilayer ceramic capacitors 10A and 10B, methods for separating and recovering rare earth and metal components from the sintering waste of multilayer ceramic capacitors 10A and 10B, which have a plating layer 34 as the outermost layer, are described respectively.

[0120] 2.1.1. Multilayer Ceramic Capacitor (1) Constructing the Multilayer Ceramic Capacitor 10A shown in FIG7, the external electrode 30 includes a sintered electrode layer 32 and a plating layer 34 disposed on the sintered electrode layer 32. The plating layer 34 is formed by a single plating layer. In the example of FIG7, the plating layer 34 includes a first lower plating layer (first stage plating layer) 34a1 and a second lower plating layer 34b1 (second stage plating layer). Furthermore, the first external electrode 30a includes a first sintered electrode layer 32a and a first lower plating layer 34a1 on the first sintered electrode layer 32a. The second external electrode 30b includes a second sintered electrode layer 32b and a second lower plating layer 34b1 on the second sintered electrode layer 32b. Furthermore, the first and second lower plating layers 34a1 and 34b1 are the outermost layers disposed on the laminate 12. The sintered electrode layer 32 serves as the substrate of the plating layer 34, and is therefore sometimes referred to as the substrate electrode layer.

[0121] (2) Separation and Recycling Method (2-1) Overview of the Separation and Recycling Method The multilayer ceramic capacitor 10A with a plating layer 34 and the multilayer ceramic capacitor 10 with a sintered electrode layer 32 as the outermost layer are similarly included in the waste after firing (firing for the sintered electrode layer). Therefore, the multilayer ceramic capacitor 10A with a plating layer 34 can be incorporated into the separation and recycling method of FIG1A. That is, in the preparation of the waste after firing in step (A), the multilayer ceramic capacitor 10A with a plating layer 34 can be prepared as the waste after firing. Thereafter, by means of the separation and recycling method described in FIG1A, the first metal component, the second metal component, and the rare earth component can be separated and recycled from the multilayer ceramic capacitor 10A with a plating layer 34.

[0122] In this method, after removing the plating layer 34 from the multilayer ceramic capacitor 10A with the plating layer 34, the first metal component, the second metal component, and the rare earth component can be recovered from the multilayer ceramic capacitor 10A. Figure 9 is a flowchart illustrating a method for separating and recovering rare earth and metal components from waste material after firing (firing for attaching electrode layers) of a multilayer ceramic capacitor with the plating layer 34 as the outermost layer, including a plating removal step (K). In the separation and recovery method of Figure 9, compared with the separation and recovery method of Figure 1A, a plating removal step (K) for removing the plating layer 34 is included between the preparation of the waste material after firing in step (A) and the miniaturization in step (B). The separation and recovery method of Figure 9 is the same as the separation and recovery method of Figure 1A except for the inclusion of step (K).

[0123] In the separation and recovery of various components from the multilayer ceramic capacitor 10A having a plating layer 34, for example, it can be divided into two cases as follows: using the separation and recovery method of FIG1A that does not include the plating removal step, or using the separation and recovery method of FIG9 that includes the plating removal step.

[0124] (2-2) In the case of using a separation and recycling method excluding the plating removal step (Fig. 1A) in a multilayer ceramic capacitor 10A having a plating layer 34, the metal components contained in the first and second lower plating layers 34a1 and 34b1 are the same as at least one of the first metal component contained in the internal electrode layer 16 and the second metal component contained in the sintered electrode layer 32. In this case, the multilayer ceramic capacitor 10A having the plating layer 34 is prepared as a post-firing waste from step (A) of Fig. 1A, and is further processed by the separation and recycling method shown in Fig. 1A in subsequent steps (B). For example, when the first and second lower plating layers 34a1 and 34b1 contain the first metal component, the first metal component of the plating layer 34 can be separated and recycled together with the first metal component contained in the internal electrode layer 16. Furthermore, for example, if the first and second lower plating layers 34a1 and 34b1 contain a second metal component, the second metal component of plating layer 34 can be separated and recovered together with the second metal component contained in the sintered electrode layer 32. Moreover, rare earth components can be separated and recovered from the ceramic layer 14.

[0125] Specific examples will be given for illustration. For instance, suppose that the first and second lower plating layers 34a1 and 34b1 are Ni-based plating layers. Also suppose that the internal electrode layer 16 contains Ni as the first metal component. In this case, without removing the first and second lower plating layers 34a1 and 34b1, a multilayer ceramic capacitor 10A is prepared as the waste material after firing in step (A) of FIG. 7A. Subsequently, through the steps following step (B) in the separation and recovery method of FIG. 1A, Ni as the first metal component can be separated and recovered from the first and second lower plating layers 34a1 and 34b1 and the internal electrode layer 16. Furthermore, the second metal component can be separated and recovered from the sintered electrode layer 32, and rare earth components can be separated and recovered from the ceramic layer 14.

[0126] For example, suppose the first and second lower plating layers 34a1 and 34b1 are both plating layers with Cu as the main component. Also suppose the sintered electrode layer 32 contains Cu as the second metal component. In this case, without removing the first and second lower plating layers 34a1 and 34b1, a multilayer ceramic capacitor 10A is prepared as the waste after firing in step (A) of FIG. 7A. Subsequently, through the steps after step (B) in the separation and recovery method of FIG. 1A, Cu as the second metal component can be separated and recovered from the first and second lower plating layers 34a1 and 34b1 and the sintered electrode layer 32. Furthermore, the first metal component can be separated and recovered from the internal electrode layer 16, and rare earth components can be separated and recovered from the ceramic layer 14.

[0127] (2-3) Separation and Recycling Method Including Plating Removal Step (Fig. 9) In the multilayer ceramic capacitor 10A having plating layer 34, it is assumed that the metal composition contained in the first and second lower plating layers 34a1 and 34b1 is different from either the first metal composition contained in the internal electrode layer 16 or the second metal composition contained in the sintered electrode layer 32. That is, the metal composition (third metal composition) contained in the first and second lower plating layers 34a1 and 34b1 is different from either the first or second metal composition. In this case, the multilayer ceramic capacitor 10A having plating layer 34 is prepared as the sintering waste after step (A) of Fig. 3. Furthermore, the first and second lower plating layers 34a1 and 34b1 are removed by plating removal in step (K). Subsequently, the multilayer ceramic capacitor 10A after removing the plating layer 34 is further processed by the steps following step (B) of the separation and recovery method shown in FIG9. In this way, the first metal component constituting the internal electrode layer 16, the second metal component constituting the sintered electrode layer 32, and the rare earth components contained in the ceramic layer 14 can be separated and recovered from the multilayer ceramic capacitor 10A after removing the plating layer 34.

[0128] Specific examples will be given below. For instance, suppose that the first and second lower plating layers 34a1 and 34b1 are plating layers with Sn (an example of a third metal component) as the main component. Also, suppose that the internal electrode layer 16 contains Ni as the first metal component and the sintered electrode layer 32 contains Cu as the second metal component. In this case, a multilayer ceramic capacitor 10A with plating layer 34 is prepared as the waste after firing in step (A) of FIG9. Furthermore, in step (K) of FIG9, the first and second lower plating layers 34a1 and 34b1 with Sn as the main component are removed. The first and second lower plating layers 34a1 and 34b1 with Sn as the main component can be removed by immersing the multilayer ceramic capacitor 10A with plating layer 34 in an alkaline solution other than ammonia, such as sodium hydroxide and potassium hydroxide. In this case, the Cu-based sintered electrode layer 32 is exposed to the alkaline solution by removing the plating layer 34. However, the Cu-based sintered electrode layer 32 is not easily corroded by the alkaline solution. Here, the alkaline solution, other than ammonia, is adjusted to approximately pH 12. Subsequently, through the steps following step (B) of the separation and recovery method in Figure 9, the first metal component constituting the internal electrode layer 16, the second metal component constituting the sintered electrode layer 32, and the rare earth components contained in the ceramic layer 14 can be separated and recovered.

[0129] The above describes the removal of the Sn-based plating layer 34 using an alkaline solution other than ammonia. However, acidic solutions such as hydrochloric acid and dilute sulfuric acid, which lack oxidizing power, can also be used to remove the Sn-based plating layer 34. In this case, the Cu-based sintered electrode layer 32 is exposed to the acidic solution by removing the plating layer 34. However, the Cu-based sintered electrode layer 32 is not easily corroded by the acidic solution. Here, the acidic solution is adjusted, for example, to approximately pH 2.

[0130] Furthermore, if the metal components contained in the first and second lower plating layers 34a1 and 34b1 are the same as at least one of the first metal component contained in the internal electrode layer 16 and the second metal component contained in the sintered electrode layer 32, a multilayer ceramic capacitor 10A with plating layer 34 can also be prepared as a post-firing waste of step (A) in FIG9. Moreover, the first and second lower plating layers 34a1 and 34b1 can also be removed by plating removal in step (K).

[0131] For example, suppose that the first and second lower plating layers 34a1 and 34b1 are Ni-based. Also suppose that the internal electrode layer 16 contains Ni as the first metal component, and the sintered electrode layer 32 contains Cu as the second metal component. In this case, a multilayer ceramic capacitor 10A with plating layers 34 is prepared as the sintering waste from step (A) of FIG9. Furthermore, in step (K) of FIG9, the first and second lower plating layers 34a1 and 34b1, which are Ni-based, are removed. The first and second lower plating layers 34a1 and 34b1, which are Ni-based, can be removed by immersing the multilayer ceramic capacitor 10A with plating layers 34 in an acidic solution that does not have oxidizing power, such as hydrochloric acid or dilute sulfuric acid. In this case, the sintered electrode layer 32, which is Cu-based, is exposed to the acidic solution by removing the plating layers 34. However, the Cu-based sintered electrode layer 32 is not easily corroded by the acidic solution. Here, the acidic solution is adjusted to approximately pH 2. Subsequently, through the steps following step (B) of the separation and recovery method shown in Figure 9, the first metal component constituting the internal electrode layer 16, the second metal component constituting the sintered electrode layer 32, and the rare earth components contained in the ceramic layer 14 can be separated and recovered.

[0132] 2.1.2. Multilayer Ceramic Capacitor with Multiple Plating Layers (1) In the multilayer ceramic capacitor 10B shown in FIG8, the external electrode 30 includes a sintered electrode layer 32 and a plating layer 34 disposed on the sintered electrode layer 32. The plating layer 34 is formed by multiple plating layers. In the example of FIG8, the plating layer 34 is formed by two plating layers. Specifically, the plating layer 34 includes: a first lower plating layer (first stage plating layer) 34a1 and a second lower plating layer (second stage plating layer) 34b1, a first upper plating layer (first stage plating layer) 34a2 and a second upper plating layer (second stage plating layer) 34b2. Furthermore, the first external electrode 30a includes: a first sintered electrode layer 32a, a first lower plating layer 34a1 on the first sintered electrode layer 32a, and a first upper plating layer 34a2 on the first lower plating layer 34a1. The second external electrode 30b includes: a second sintered electrode layer 32b, a second lower plating layer 34b1 on the second sintered electrode layer 32b, and a second upper plating layer 34b2 on the second lower plating layer 34b1. Furthermore, the first upper plating layer 34a2 and the second upper plating layer 34b2 are the outermost layers disposed on the laminate 12.

[0133] The multilayer ceramic capacitor 10B having a plating layer 34 as its outermost layer is formed after steps (1) to (7) of the multilayer ceramic capacitor 10 having a sintered electrode layer as its outermost layer, by step (8) of placing the plating layer 34 on the sintered electrode layer 32. In step (8), a first lower plating layer 34a1 and a first upper plating layer 34a2 are sequentially formed on the first sintered electrode layer 32a by performing a plating process, and a second upper plating layer 34b2 is sequentially formed on the second lower plating layer 34b1 on the second sintered electrode layer 32b.

[0134] (2) Separation and Recycling Method (2-1) Overview of the Separation and Recycling Method The multilayer ceramic capacitor 10B with a plating layer 34 and the multilayer ceramic capacitor 10 with a sintered electrode layer 32 as the outermost layer are similarly included in the waste after firing (firing for the sintered electrode layer). Therefore, the multilayer ceramic capacitor 10B with a plating layer 34 can be incorporated into the separation and recycling method of FIG. 1A. That is, in the preparation of the waste after firing in step (A), the multilayer ceramic capacitor 10B with a plating layer 34 can be prepared as the waste after firing. Subsequently, by means of the separation and recycling method described in FIG. 1A, the first metal component, the second metal component, and the rare earth component can be separated and recycled from the multilayer ceramic capacitor 10B with a plating layer 34.

[0135] Alternatively, after removing the plating layer 34 of the multilayer ceramic capacitor 10B, the first metal component, the second metal component, and the rare earth component can be recovered from the multilayer ceramic capacitor 10B.

[0136] In the separation and recovery of various components from the multilayer ceramic capacitor 10B having a plating layer 34, for example, it can be divided into two cases as follows: using the separation and recovery method of FIG1A that does not include the plating removal step, or using the separation and recovery method of FIG9 that includes the plating removal step.

[0137] (2-2) In the case of using a separation and recycling method excluding the plating removal step (Fig. 1A) in a multilayer ceramic capacitor 10B having plating layer 34, the metal components contained in the first and second lower plating layers 34a1, 34b1 and the first and second upper plating layers 34a2, 34b2 are the same as at least one of the first metal component contained in the internal electrode layer 16 and the second metal component contained in the sintered electrode layer 32. In this case, the multilayer ceramic capacitor 10B having plating layer 34 is prepared as a post-firing waste from step (A) of Fig. 7A and processed by the separation and recycling method shown in Fig. 1A. For example, the metal components of the first and second lower plating layers 34a1, 34b1 may be the same as the first metal component contained in the internal electrode layer 16. Furthermore, the metal composition of the first and second upper plating layers 34a2 and 34b2 can be the same as the second metal composition contained in the sintered electrode layer 32. Alternatively, for example, the metal composition of the first and second lower plating layers 34a1 and 34b1 can be the same as the second metal composition contained in the sintered electrode layer 32. Furthermore, the metal composition of the first and second upper plating layers 34a2 and 34b2 can be the same as the first metal composition contained in the inner electrode layer 16. In this case, the first and second metal compositions of the plating layer 34 can be separated and recovered together with the first metal composition contained in the inner electrode layer 16 and the second metal composition contained in the sintered electrode layer 32. Moreover, rare earth components can be separated and recovered from the ceramic layer 14.

[0138] Specific examples will be given below. For instance, suppose the first and second lower plating layers 34a1 and 34b1 are plating layers with Ni (or Cu) as the main component. Also, suppose the first and second upper plating layers 34a2 and 34b2 are plating layers with Cu (or Ni) as the main component. Also, suppose the internal electrode layer 16 contains Ni as the first metal component. Also, suppose the sintered electrode layer 32 contains Cu as the second metal component. In this case, without removing the first and second lower plating layers 34a1 and 34b1 and the first and second upper plating layers 34a2 and 34b2, a multilayer ceramic capacitor 10B is prepared as a post-firing waste from step (A) of FIG. 1A. Subsequently, through the steps following step (B) of the separation and recovery method shown in Figure 1A, Ni as the first metal component and Cu as the second metal component can be separated and recovered from the first and second lower plating layers 34a1 and 34b1, the first and second upper plating layers 34a2 and 34b2, the internal electrode layer 16, and the sintered electrode layer 32. Furthermore, rare earth components can be separated and recovered from the ceramic layer 14.

[0139] (2-3) Separation and Recycling Method Including Plating Removal Step (Fig. 9) As an example, suppose that in the multilayer ceramic capacitor 10B having plating layer 34, the metal component (third metal component) contained in the first and second lower plating layers 34a1, 34b1 and the first and second upper plating layers 34a2, 34b2 is different from either the first metal component contained in the internal electrode layer 16 or the second metal component contained in the sintered electrode layer 32. In this case, the multilayer ceramic capacitor 10B having plating layer 34 is prepared as the sintering waste in step (A) of Fig. 9. Furthermore, the first and second lower plating layers 34a1, 34b1 and the first and second upper plating layers 34a2, 34b2 are removed by plating removal in step (K). Subsequently, the multilayer ceramic capacitor 10B after removing the plating layer 34 is further processed by the steps following step (B) of the separation and recovery method shown in FIG9. In this way, the first metal component constituting the internal electrode layer 16, the second metal component constituting the sintered electrode layer 32, and the rare earth components contained in the ceramic layer 14 can be separated and recovered from the multilayer ceramic capacitor 10B after removing the plating layer 34.

[0140] Furthermore, as another example, suppose that in the multilayer ceramic capacitor 10B having plating layer 34, the third metal component contained in the first and second upper plating layers 34a2 and 34b2 is different from either the first metal component contained in the inner electrode layer 16 or the second metal component contained in the sintered electrode layer 32. On the other hand, suppose that the metal component contained in the first and second lower plating layers 34a1 and 34b1 is the same as either the first metal component contained in the inner electrode layer 16 or the second metal component contained in the sintered electrode layer 32. In this case, the multilayer ceramic capacitor 10B having plating layer 34 is prepared as a post-firing waste in step (A) of FIG. 9. Furthermore, the first and second upper plating layers 34a2 and 34b2 are removed by plating removal in step (K). Subsequently, the multilayer ceramic capacitor 10B after removing the first and second upper plating layers 34a2 and 34b2 is further processed by the steps following step (B) of the separation and recovery method shown in FIG9. In this way, the metal components (first metal component or second metal component) contained in the first and second lower plating layers 34a1 and 34b1, the first metal component constituting the internal electrode layer 16, the second metal component constituting the sintered electrode layer 32, and the rare earth components contained in the ceramic layer 14 can be separated and recovered from the multilayer ceramic capacitor 10B after removing the first and second upper plating layers 34a2 and 34b2.

[0141] Furthermore, a specific example will be given to illustrate another example mentioned above. For instance, suppose that the metal components contained in the first and second upper plating layers 34a2 and 34b2 are plating layers with Sn (an example of a third metal component) as the main component. Also, suppose that the metal components contained in the first and second lower plating layers 34a1 and 34b1 are plating layers with Ni (or Cu) as the main component. Also, suppose that the internal electrode layer 16 contains Ni as the first metal component, and the sintered electrode layer 32 contains Cu as the second metal component. In this case, a multilayer ceramic capacitor 10B with plating layers 34 is prepared as the waste after firing in step (A) of FIG9. And, in step (K) of FIG9, the first and second upper plating layers 34a2 and 34b2 with Sn as the main component are removed. The first and second upper plating layers 34a2 and 34b2, which are mainly composed of Sn, can be removed by immersing the multilayer ceramic capacitor 10B with the plating layers 34 in an alkaline solution other than ammonia, such as sodium hydroxide or potassium hydroxide. In this case, the first and second lower plating layers 34a1 and 34b1, which are mainly composed of Ni (or Cu), are exposed to the alkaline solution by removing the first and second upper plating layers 34a2 and 34b2. However, the first and second lower plating layers 34a1 and 34b1, which are mainly composed of Ni (or Cu), are not easily corroded by the alkaline solution. Furthermore, the sintered electrode layer 32, which is mainly composed of Cu, is also not easily corroded by the alkaline solution. Here, the alkaline solution other than ammonia is adjusted to approximately pH 12. Subsequently, through the steps following step (B) of the separation and recovery method shown in Figure 9, Ni as the first metal component and Cu as the second metal component can be separated and recovered from the first and second lower plating layers 34a1 and 34b1, the internal electrode layer 16, and the sintered electrode layer 32. Furthermore, rare earth components can be separated and recovered from the ceramic layer 14.

[0142] In another specific example described above, only the first and second upper plating layers 34a2 and 34b2 are removed in step (K). However, both the first and second upper plating layers 34a2 and 34b2 and the first and second lower plating layers 34a1 and 34b1 can be removed. For example, suppose that the metal composition contained in the first and second upper plating layers 34a2 and 34b2 is Sn (an example of a third metal composition). Also, suppose that the metal composition contained in the first and second lower plating layers 34a1 and 34b1 is Ni and not Cu. Also, suppose that the internal electrode layer 16 contains Ni as the first metal composition and the sintered electrode layer 32 contains Cu as the second metal composition. In this case, a multilayer ceramic capacitor 10B with plating layers 34 is prepared as a post-firing waste from step (A) of FIG9. Furthermore, in step (K) of Figure 9, the first and second upper plating layers 34a2 and 34b2, which are mainly composed of Sn, and the first and second lower plating layers 34a1 and 34b1, which are mainly composed of Ni, are removed. The first and second upper plating layers 34a2 and 34b2, which are mainly composed of Sn, and the first and second lower plating layers 34a1 and 34b1, which are mainly composed of Ni, can be removed by immersing the multilayer ceramic capacitor 10B with plating layers 34 in an acidic solution that does not have oxidizing power, such as hydrochloric acid or dilute sulfuric acid. In this case, the sintered electrode layer 32, which is mainly composed of Cu, is exposed to the acidic solution by removing the plating layer 34. However, the sintered electrode layer 32, which is mainly composed of Cu, is not easily corroded by the acidic solution. Here, the acidic solution is adjusted to approximately pH 2, for example. Subsequently, through the steps following step (B) of the separation and recovery method shown in Figure 9, Ni as the first metal component and Cu as the second metal component can be separated and recovered from the internal electrode layer 16 and the sintered electrode layer 32. Furthermore, rare earth components can be separated and recovered from the ceramic layer 14.

[0143] In the above, the first and second upper plating layers 34a2 and 34b2, which are mainly composed of Sn, and the first and second lower plating layers 34a1 and 34b1, which are mainly composed of Ni, are removed in one step using an acidic solution that does not have oxidizing power. However, they can also be removed sequentially. First, the first and second upper plating layers 34a2 and 34b2, which are mainly composed of Sn, are removed by immersing the multilayer ceramic capacitor 10B in an alkaline solution (e.g., about pH 12) other than ammonia, such as sodium hydroxide and potassium hydroxide. Then, the first and second lower plating layers 34a1 and 34b1, which are mainly composed of Ni, are removed by immersing the multilayer ceramic capacitor 10B in an acidic solution (e.g., about pH 2) that does not have oxidizing power, such as hydrochloric acid and dilute sulfuric acid. Subsequently, through the steps following step (B) of the separation and recovery method shown in Figure 9, Ni as the first metal component and Cu as the second metal component can be separated and recovered from the internal electrode layer 16 and the sintered electrode layer 32. Furthermore, rare earth components can be separated and recovered from the ceramic layer 14.

[0144] 2.2. The effect can also be achieved by separating and recovering the first metal component constituting the inner electrode layer 16, the second metal component constituting the outer electrode 30, and the rare earth components contained in the ceramic layer 14 from the multilayer ceramic capacitors 10A and 10B with the plating layer 34 as the outermost layer, in the same manner as the multilayer ceramic capacitor 10 with the sintered electrode layer 32 as the outermost layer, using the separation and recovery method shown in FIG1A or FIG9. Furthermore, by employing a separation and recovery method suitable for separating and recovering the metal components from the plating layer 34, the first metal component and the second metal component can sometimes also be recovered from the plating layer 34.

[0145] Furthermore, as described above, the embodiments of the present invention have been disclosed in the foregoing description, but the present invention is not limited thereto. That is, various changes can be made to the mechanism, shape, material, quantity, position or arrangement of the embodiments described above without departing from the technical concept and purpose of the present invention, and such changes are included in the present invention.

[0146] 3. Other variations

[0147] The following describes variations of two methods applicable to the separation and recycling of post-firing waste from multilayer ceramic capacitors 10 with sintered electrode layer 32 as the outermost layer, and the separation and recycling of post-firing waste from multilayer ceramic capacitors 10A and 10B with plating layer 34 as the outermost layer. (1) In step (B), a slurry is generated using an aqueous solvent. In the above embodiment, the post-firing waste is pulverized in step (B) to make it fine. However, as long as the post-firing waste can be fined, it can be done simultaneously with or instead of the fineness in step (B) (especially fineness by pulverization) by using a solvent (such as an aqueous solvent) to disperse the post-firing waste into a slurry state, thereby performing fineness. Here, fineness by mixing the post-firing waste and the solvent to form a slurry is called wet fineness. Furthermore, in wet micronization, the micronization of a slurry formed by mixing calcined waste with solvent is called wet micronization. Moreover, water can be used as a water-based solvent.

[0148] Furthermore, in the above embodiments, during the magnetic separation in step (C), the micronized post-calcination waste can be dispersed by mixing it with an aqueous solvent such as water in step (B) to form a slurry. However, as mentioned above, when the post-calcination waste is made into a slurry using an aqueous solvent simultaneously with or instead of the micronization in step (B), the magnetic separation of the post-calcination waste in the slurry state can be performed in step (C). That is, the time spent generating the slurry state in the magnetic separation in step (C) can be omitted.

[0149] Furthermore, the use of organic solvents to slurry-like transform the calcination waste is also considered. However, when using organic solvents to slurry-like transform the calcination waste, a step to remove the organic solvent is required in the separation and recovery method. Therefore, it is preferable to use aqueous solvents such as water to slurry-like transform the calcination waste.

[0150] (2) Other Examples Included in the Firing Waste In the above embodiments, the firing waste refers to the waste from the firing of the electrode layer in step 7. However, the firing waste is not limited to this. The firing waste may also include waste that was fired before the firing of the electrode layer and has been fired before being fed into the separation and recycling methods of Figures 1A and 9. In this case, the firing is preferably carried out at the firing temperature for firing the electrode layer.

[0151] Waste materials before firing for applying electrode layers can be exemplified by the waste materials discharged in steps (1) to (6). Furthermore, waste materials before firing for applying electrode layers can include the waste materials from step (7) after the electrode layer paste is applied to the laminate 12, but before firing for applying electrode layers. Specifically, waste materials before firing for applying electrode layers can be exemplified by: (1) dielectric paste waste, conductive paste waste for internal electrode layers, (2) dielectric sheet waste with internal electrode layer patterns formed, dielectric sheet without internal electrode layer patterns printed, (4) excess laminate blocks such as scraps from laminate blocks discharged after cutting, defective laminated wafers after cutting, (5) waste after degreasing, and (6) waste materials after firing the laminated wafers.

[0152] (3) Other multilayer ceramic capacitors that discharge post-firing waste: In the above embodiments, as the manufactured multilayer ceramic capacitors, a two-terminal multilayer ceramic capacitor is described below, which has two terminals, a first external electrode 30a and a second external electrode 30b. However, the application scope of the present invention is not limited to the post-firing waste of two-terminal multilayer ceramic capacitors. The present invention is applied to the post-firing waste of multilayer ceramic capacitors, which have: an inner electrode layer containing a first metal component such as Ni; an outer electrode containing a second metal component such as Cu; and a ceramic layer containing a dielectric material such as BaTiO3 and rare earth components such as Dy as additives. Therefore, the present invention can also be applied, for example, to the post-firing waste of three-terminal multilayer ceramic capacitors.

[0153] For example, a 3-terminal multilayer ceramic capacitor has a multilayer body 12 and first to fourth external electrodes, similar to those in the embodiment described above. The internal electrode layer 16 has a first internal electrode layer led to a first end face 12e and a second end face 12f, and a second internal electrode layer led to a first side face 12c and a second side face 12d. A first external electrode is disposed on the first end face 12e of the multilayer body 12. The first external electrode is electrically connected to the first internal electrode layer exposed on the first end face 12e of the multilayer body 12. A second external electrode is disposed on the second end face 12f of the multilayer body 12. The second external electrode is electrically connected to the first internal electrode layer exposed on the second end face 12f of the multilayer body 12. A third external electrode is disposed on the first side face 12c of the multilayer body 12. The third external electrode is electrically connected to the second internal electrode layer exposed on the first side face 12c of the multilayer body 12. The fourth external electrode is disposed on the second side 12d of the laminate 12. The fourth external electrode is electrically connected to the second internal electrode layer exposed on the second side 12d of the laminate 12. The first to fourth external electrodes may consist only of a sintered electrode layer, or may consist of a sintered electrode layer and a plating layer.

[0154] (4) Regarding the filtration in step (F) in step (D), if the second separated product is dissolved in an inorganic acid without oxidizing power, the ceramic microparticles contained in the second separated product will react with the inorganic acid without oxidizing power, thereby forming undissolved matter and precipitating. Furthermore, the second metal microparticles, such as Cu, have a lower ionization tendency than the hydrogen ions contained in the inorganic acid without oxidizing power, and therefore are insoluble in the inorganic acid without oxidizing power. On the other hand, the rare earth components in the rare earth-containing product dissolve to form a solution containing rare earth components. The solution containing the undissolved matter and rare earth components can also be recovered as the rare earth components. In this case, the solid-liquid separation step (F), such as filtration, can be omitted.

[0155] (5) Omitting step (G) In the above embodiment, during the dissolution of the second isolate in step (D), rare earth components can be separated and recovered as a solution containing rare earth components. Therefore, the neutralization step (G) can be omitted.

[0156] (6) Omission of various processes in step (I) In the above embodiment, the first metal component can be separated and recovered in the electrolytic refining of step (H). Therefore, various processes in step (I) can be omitted.

[0157] (7) Other methods for separating and recovering rare earth components In the above embodiments, in step (G) and , rare earth components such as Dy(OH)3 are separated and recovered as rare earth components. However, the separation and recovery of rare earth components is not limited to this. For example, as an example, rare earth components can be recovered in the following manner.

[0158] (a) The rare earth compound obtained by neutralization in step (G) is subjected to heat treatment to generate an oxide, thereby recovering the oxide as a rare earth component. For example, if the rare earth compound obtained after neutralization in step (G) is Dy(OH)3, dysprosium oxide (Dy2O3) can be recovered as a rare earth component by heat treatment of Dy(OH)3.

[0159] (b) The rare earth compound obtained by neutralization in step (G) is dissolved in hydrochloric acid to generate chloride, which can then be recovered as a rare earth component. For example, if the rare earth compound obtained after neutralization in step (G) is Dy(OH)3, Dy(OH)3 is dissolved in hydrochloric acid to generate a dysprosium chloride (DyCl3) solution. By distilling to remove the dysprosium chloride solution and evaporating the solvent, dysprosium chloride hexahydrate (DyCl3·6H2O) can be recovered as a rare earth component.

[0160] (c) Similarly to (b) above, by dissolving the rare earth compound Dy(OH)3 obtained after neutralization in step (G) in hydrochloric acid, a dysprosium chloride solution is generated. Subsequently, by further refining, high-purity rare earth components can be recovered. For example, by refining the dysprosium chloride solution generated as described above using solvent extraction, a high-purity dysprosium chloride solution as a rare earth component can be recovered. Solvent extraction is a separation and refining method that transfers a solute dissolved in one of the immiscible liquid phases (oil or aqueous) to the other, utilizing the solute's distribution. Other methods besides solvent extraction include, for example, ion exchange resin methods.

[0161] (d) Furthermore, high-purity dysprosium oxide (Dy₂O₃) can be recovered from the high-purity dysprosium chloride solution obtained by solvent extraction as 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. By filtering the precipitate, high-purity dysprosium oxalate hexahydrate (Dy₂(C₂O₄)₃·6H₂O) is recovered. By heat treatment of the high-purity dysprosium oxalate hexahydrate, high-purity dysprosium oxide (Dy₂O₃) can be recovered as a rare earth component.

[0162] (e) Furthermore, high-purity dysprosium chloride hexahydrate can be recovered from a high-purity dysprosium chloride solution obtained using the solvent described in (c) above. In this case, for example, the high-purity dysprosium chloride hexahydrate can be recovered by distilling away the high-purity dysprosium chloride solution to evaporate the solvent.

[0163] (f) In the above embodiment, the solution containing rare earth components separated and recovered in the filtration of step (F) is added to step (G) for further processing. However, the solution containing rare earth components separated and recovered in the filtration of step (F) may also be processed in the rare earth component concentration step before being added to step (G) for further processing. That is, the rare earth component concentration step is performed after the filtration of step (F) and before the processing of step (G).

[0164] As a rare earth component concentration step, there is no limitation as long as it is a method that can increase the recovery of rare earth components in a solution containing rare earth components. Examples of rare earth component concentration steps include (f1) ion exchange, (f2) solvent extraction, and (f3) distillation to remove solvent from solution, but these are not limited to. Hereinafter, (f1) to (f3) will be described as representative examples.

[0165] (f1) Ion Exchange Method The ion exchange method is a method in which dissolved ions in a solvent are adsorbed onto ion exchangers such as ion exchange resins and chelating resins. For example, by passing a solution containing rare earth elements through an ion exchanger, the rare earth elements in the solution are adsorbed onto the ion exchanger. The ion exchange method is not particularly limited; for example, it can be implemented by passing a solution containing rare earth elements through a column filled with ion exchangers. For example, the column is formed by a cylindrical body open at both the top and bottom. A solution containing rare earth elements is introduced into the column from the top side, and the rare earth elements are adsorbed onto the ion exchanger during the passage. The remaining solution containing rare earth elements after passing through the ion exchanger is discharged from the bottom side of the column.

[0166] Secondly, the rare earth components adsorbed on the ion exchanger are dissolved from the ion exchanger using a solvent. For example, the solvent passes through the lower end of the column filled with the ion exchanger containing the adsorbed rare earth components. As a result, the rare earth components are dissolved from the ion exchanger into the solvent. The solvent after the rare earth components have dissolved is recovered from the upper end of the column. The rare earth components can be recovered by filtering the solvent containing the dissolved rare earth components, for example, using a filter. Depending on the throughput of the solution containing rare earth components, the ease with which the rare earth components are adsorbed on the ion exchanger, and the amount of solvent, the concentration of rare earth components in the solvent can be higher than the concentration of rare earth components in the solution containing rare earth components.

[0167] In the above process, the solution containing rare earth elements flows from the upper end of the column to the lower end, and then the precipitant flows from the lower end of the column to the upper end. However, as long as the rare earth elements are adsorbed onto the ion exchanger and then dissolved in the precipitant, the direction of flow of the solution containing rare earth elements and the precipitant in the column is not limited.

[0168] Furthermore, the series of steps (1), including steps (A) to (F) and the concentration step of rare earth components using ion exchange, can be performed only once. For example, by passing the solution containing rare earth components after steps (A) to (F) through an ion exchanger once, the series of steps (1) can be performed only once.

[0169] Alternatively, a series of steps (1), including steps (A) to (F) and the concentration step of rare earth components using ion exchange, can be performed multiple times. For example, a series of steps (1) can be performed, in which a solution containing rare earth components after multiple passes through steps (A) to (F) is passed through an ion exchanger. In this case, the same ion exchanger can be used in each series of steps (1). By passing the solution containing rare earth components recovered from multiple passes through the same ion exchanger, more rare earth components than those recovered from a single pass through steps (A) to (F) are adsorbed onto the ion exchanger. Therefore, the concentration of rare earth components in the solvent can be increased, and the recovery rate of rare earth components can be increased.

[0170] Alternatively, after performing a series of steps (2) including steps (A) to (F) multiple times, the solutions containing rare earth elements obtained in each series of steps (2) are temporarily stored. Subsequently, the stored solutions containing rare earth elements can be processed in one step using a rare earth element concentration step via ion exchange. The amount of rare earth element-containing solution stored through a series of steps (2) is greater than the amount obtained through a single series of steps (2). Therefore, by passing the stored solution containing rare earth elements through an ion exchanger, more rare earth elements can be adsorbed onto the ion exchanger, thus increasing the recovery rate of rare earth elements.

[0171] Furthermore, when the concentration of rare earth components in the solution is low after a series of steps (2) from (A) to (F), even if the solution is filtered, the amount of rare earth components deposited on the filter is also small. Therefore, the recovery rate of rare earth components is sometimes low. However, by performing the rare earth component concentration step as described above, the recovery rate of rare earth components can be increased.

[0172] There are no particular limitations on the ion exchange resins used as ion exchangers; examples include cation exchange resins and chelating resins. There are also no particular limitations on cation exchange resins; examples include gel-type cation exchange resins, strongly acidic cation exchange resins, and weakly acidic cation exchange resins. Furthermore, specifically, there are no particular limitations on cation exchange resins; examples include Amberlite IR-120B (manufactured by Organo Corporation), Duolite C20J (manufactured by Sumika Chemtex Corporation), DIAION SK-110 (manufactured by Mitsubishi Chemical Corporation), and Purolite C100 (manufactured by Purolite Corporation).

[0173] There are no particular limitations on chelating resins used as ion exchangers. Examples include resins with chelating groups or chelating abilities such as thiourea, thiourea-onium, phosphonic acid, aminophosphate, aminocarboxylic acid, alkylamine, pyridine ring, cyclic anthocyanin, and cyclic ether. Furthermore, specifically, there are no particular limitations on chelating resins; examples include Sumichelate MC700 (manufactured by Sumika Chemtex) and Purolite MTS9300 (manufactured by Purolite).

[0174] (f2) Solvent Extraction Method The solvent extraction method, for example, consists of a solvent extraction step and a back-extraction step. The solvent extraction step involves contacting and mixing a water-insoluble organic phase containing a metal extractant with the water-containing solution to separate the rare earth components from the rare earth components. After the solvent extraction step, a phase separation step is performed to separate the water-insoluble organic phase containing rare earth components from the aqueous phase. The phase separation step utilizes the specific gravity difference between the water-insoluble organic phase containing rare earth components and the aqueous phase after the solvent extraction step to separate the phases.

[0175] In the back-extraction step, the rare earth-containing insoluble organic phase obtained through the above phase separation step is contacted and mixed with an acidic aqueous solution, thereby back-extracting the rare earth components in the insoluble organic phase into the acidic aqueous solution.

[0176] Alternatively, a series of steps (1) including steps (A) to (F) and the concentration step of rare earth components using solvent extraction can be performed only once.

[0177] Alternatively, a series of steps (1) including steps (A) to (F) and a rare earth component concentration step using solvent extraction can be performed multiple times. For example, a series of steps (1) can be performed to mix the solution containing rare earth components after steps (A) to (F) with an organic solvent multiple times. For example, by repeatedly mixing the solution containing rare earth components recovered from multiple steps (A) to (F) with the same organic solvent, more rare earth components than those recovered from a single step (A) to (F) can be transferred to the organic solvent. Therefore, the recovery rate of rare earth components can be increased.

[0178] Alternatively, after performing a series of steps (2) including steps (A) to (F) multiple times, the solutions containing rare earth components obtained in each series of steps (2) are temporarily stored. Subsequently, the stored solutions containing rare earth components can be processed in one step by using a rare earth component concentration step of solvent extraction.

[0179] (f3) Removal of solvent from solution by distillation: This involves removing the solvent from a solution in which ions are dissolved. Solvent removal by distillation can be performed using, for example, an evaporator, but is not limited to this. An evaporator is a device that evaporates the solvent by heating and depressurizing, for example, an evaporating tank containing a solution. Examples of evaporators include rotary evaporators and flash evaporators. The operating conditions of the evaporator are appropriately adjusted according to the amount of unburned waste processed before or after degreasing, and the various components added to such unburned waste.

[0180] Alternatively, a series of steps (1) including steps (A) to (F) and the rare earth component concentration step by removing the solvent from the solution by distillation can be performed only once, or multiple times.

[0181] Alternatively, after performing a series of steps (2) including steps (A) to (F) multiple times, the solutions containing rare earth elements obtained in each series of steps (2) are temporarily stored. Subsequently, the solvent can be removed by distillation through a single treatment of the stored solutions containing rare earth elements.

[0182] (g) The state of the rare earth components: The recovered rare earth components may be in any of the following states: liquid, solid, or a mixture of liquid and solid. Furthermore, the crystal lattice of the rare earth components may be in any of the following states: amorphous, crystalline, or a mixture of amorphous and crystalline.

[0183] (8) Other methods for separating and recovering the first metal component In the above embodiments, the first metal component is separated and recovered as a first metal component compound in various processes of step (I). However, the separation and recovery of the first metal component is not limited to this. For example, the first metal component can be recovered in the following manner.

[0184] (a) In the various processes of step (I), the first metal component can be recovered as the first metal component compound by crystallizing the first metal solution obtained by reacting the first metal component with the solution. For example, if the first metal solution obtained after the various processes of step (I) is a nickel sulfate (NiSO4) solution, nickel sulfate hexahydrate (NiSO4·6H2O) can be recovered as the first metal component by crystallizing the nickel sulfate solution and filtering it.

[0185] (b) In the various processes of step (I), a high-purity first metal component can be recovered by refining the first metal solution formed by reacting the first metal component with the solution. For example, a high-purity nickel sulfate solution can be recovered as the first metal component by refining the nickel sulfate (NiSO4) solution used as the first metal solution using ion exchange resin method, solvent extraction method, etc.

[0186] (c) By crystallizing the high-purity nickel sulfate solution recovered in (b) above and filtering it, nickel sulfate hexahydrate (NiSO4·6H2O) can be recovered as the first metal component.

[0187] (d) By processing the high-purity Ni recovered in the electrolytic refining step (H), nickel chloride hexahydrate (NiCl2·6H2O) can be recovered as the first metal component. For example, by dissolving the high-purity Ni recovered in the electrolytic refining step (H) in hydrochloric acid, a high-purity nickel chloride (NiCl2) solution is generated. By spray drying the nickel chloride solution, high-purity nickel chloride hexahydrate is generated. Furthermore, by hot air drying the high-purity nickel chloride hexahydrate, an even higher purity nickel chloride hexahydrate can be recovered as the first metal component.

[0188] (e) In the various processes of step (I), the first metal solution, formed by reacting the metal component with the solution, is neutralized to generate chloride, thereby recovering the chloride as the first metal component. For example, the nickel sulfate solution, which is the first metal solution, is neutralized by adjusting the pH to, for example, about 10 (pH above 9 and below 11) using an alkali such as sodium hydroxide or potassium hydroxide, causing nickel hydroxide (Ni(OH)2) to precipitate. The precipitated nickel hydroxide (Ni(OH)2) is separated and recovered, for example, by filtration. Furthermore, nickel hydroxide is dissolved in hydrochloric acid to generate a nickel chloride (NiCl2) solution. Next, the nickel chloride solution is removed by distillation to evaporate the solvent, and nickel chloride hexahydrate (NiCl2·6H2O) can be recovered as the first metal component.

[0189] (f) The state of the first metallic component: The recovered metallic component may be in any of the following states: liquid, solid, or a mixture of liquid and solid. Furthermore, the crystal lattice of the metallic component may be in any of the following states: amorphous, crystalline, or a mixture of amorphous and crystalline.

[0190] (9) Other manufacturing steps of the multilayer ceramic capacitor In the above embodiment, the manufacturing method of the multilayer ceramic capacitor 10 sequentially includes: (step 3) forming a multilayer block, (step 4) cutting into multilayer wafers, (step 5) degreasing, (step 6) firing the multilayer wafers, and (step 7) applying and firing the electrode layer paste. However, the manufacturing method of the multilayer ceramic capacitor 10 is not limited to this. For example, sometimes the electrode layer paste is applied to the unfired multilayer wafer before degreasing in step 5 and before firing (firing of the multilayer wafer) in step 6, and then degreasing and firing of the electrode layer are performed. That is, firstly, the electrode layer paste containing Ni, glass components, resin components, etc., is applied to the multilayer wafer before degreasing in step 5. Secondly, the multilayer wafer coated with the electrode layer paste is degreased, and then firing for electrode layer application is performed. The degreasing temperature is, for example, above 800°C, but preferably below 1000°C. The firing temperature for applying the electrode layer is, for example, above 1000°C, but preferably below 1400°C. These steps are performed after cutting into multilayer wafers in step 4 of the above manufacturing method and before the plating step in step 8. Furthermore, in these steps, the firing of the multilayer wafers in step 6 and the firing of the electrode layer paste in step 7 are performed in a single firing process.

[0191] <1> A method for separating and recovering rare earth and metal components from sintering waste of multilayer ceramic capacitors includes the following steps: (A) preparing sintering waste of multilayer ceramic capacitors, wherein the sintering waste of multilayer ceramic capacitors comprises a multilayer body including a ceramic layer and an internal electrode layer, and a sintered electrode layer disposed on the multilayer body as the outermost layer and connected to the internal electrode layer. The sintered electrode layer is the sintering waste of the multilayer ceramic capacitor after sintering, wherein the ceramic layer has an aggregate of a plurality of ceramic particles, and rare earth inclusions containing rare earth components are contained at the grain boundaries between the plurality of ceramic particles; the internal electrode layer contains a first metal component as a base metal with magnetic properties; the sintered electrode layer contains a second metal component as a noble metal without magnetic properties; and the ceramic layer, the internal electrode layer, and the sintered electrode layer are sintered. (B) A step of obtaining ceramic microparticles formed by micronizing the above-mentioned calcined waste, the above-mentioned rare earth inclusions, the above-mentioned first metal microparticles formed by micronizing the above-mentioned internal electrode layer, and the above-mentioned second metal microparticles formed by micronizing the above-mentioned calcined electrode layer by micronizing the above-mentioned calcined waste; (C) A step of separating the above-mentioned calcined waste after step (B) into a first separator containing the above-mentioned ceramic microparticles and the above-mentioned first metal microparticles using a magnet; and a step of recovering a second separator containing the above-mentioned ceramic microparticles, the above-mentioned rare earth inclusions, and the above-mentioned second metal microparticles; and (H) A step of recovering the above-mentioned first metal component from the above-mentioned first separator after step (C) by electrolytic refining.

[0192] <2> like <1> The method for separating and recovering rare earth and metal components from the sintering waste of multilayer ceramic capacitors described herein, wherein in step (H) above, the metal powder contained therein is added in a processed block state, and the metal powders are in contact with each other to the extent that the current flows during the above electrolytic refining.

[0193] <3> like <1> or <2> The method for separating and recovering rare earth and metal components from the sintering waste of multilayer ceramic capacitors described herein includes step (C) above, in step (B) above, mixing the micronized sintering waste with an aqueous solvent to generate a slurry, and then using the magnet described above to recover the first and second separated components respectively.

[0194] <4> like <1> to <3> The method for separating and recovering rare earth and metal components from the sintering waste of multilayer ceramic capacitors as described in any one of the following methods further includes the following steps: (D) dissolving the second separated product after step (C) in at least one inorganic acid selected from the group containing dilute sulfuric acid and hydrochloric acid that does not have oxidizing power, thereby precipitating the ceramic microparticles and the second metal microparticles in the second separated product, and generating a solution containing rare earth components dissolved in the rare earth components.

[0195] <5> like <4> The method for separating and recovering rare earth and metal components from the sintering waste of multilayer ceramic capacitors described herein, wherein in step (D) above, the solution containing rare earth components is adjusted to a pH value of 1.5 or higher and a pH value of 2.5 or lower by adding the aforementioned inorganic acid which does not have oxidizing power.

[0196] <6> like <4> or <5> The method for separating and recovering rare earth and metal components from the sintering waste of multilayer ceramic capacitors described herein further includes the following steps: (E) dissolving the ceramic microparticles and the second metal microparticles precipitated in the second separator in the above step (D) in ammonia water, thereby precipitating the ceramic microparticles in the second separator and generating a second metal solution containing the second metal component contained in the second metal microparticles.

[0197] <7> like <6> The method for separating and recovering rare earth and metal components from the sintering waste of multilayer ceramic capacitors described herein, wherein in step (E) above, the pH of the second metal solution is adjusted to be above 9 and below 10 by adding the aforementioned ammonia water.

[0198] <8> like <4> to <7> The method for separating and recovering rare earth and metal components from the sintering waste of multilayer ceramic capacitors as described in any one of the methods further includes the following step: (F) performing solid-liquid separation on the solution containing the rare earth components, which includes the precipitated ceramic microparticles and the undissolved second metal microparticles.

[0199] <9> like <8> The method for separating and recovering rare earth and metal components from the sintering waste of multilayer ceramic capacitors described herein further includes, after step (F) above, a rare earth component concentration step for concentrating the rare earth components in the solution containing rare earth components.

[0200] <10> like <1> to <9> The method for separating and recovering rare earth and metal components from the sintering waste of multilayer ceramic capacitors as described in any one of the following, wherein the first metal component is Ni.

[0201] <11> like <1> to <10> The method for separating and recovering rare earth and metal components from the sintering waste of multilayer ceramic capacitors as described in any one of the following, wherein the second metal component is Cu.

[0202] <12> like <1> or <2> The method described herein is for separating and recovering rare earth and metal components from the waste material after firing of multilayer ceramic capacitors, wherein the ceramic particles are BaTiO3.

[0203] <13> like <1> to <12> The method for separating and recovering rare earth and metallic components from the sintering waste of multilayer ceramic capacitors as described in any one of the following: wherein the rare earth components are at least one of Dy, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb, and Lu.

[0204] <14> A method for separating and recovering rare earth and metal components from sintering waste of multilayer ceramic capacitors includes the following steps: (A) preparing sintering waste of multilayer ceramic capacitors, wherein the sintering waste of multilayer ceramic capacitors comprises a multilayer body including a ceramic layer and an internal electrode layer, a sintered electrode layer disposed on the multilayer body and connected to the internal electrode layer, and the sintered electrode layer disposed on the sintered electrode layer as the outermost first-stage plating layer of the multilayer ceramic capacitor after sintering, wherein the ceramic layer has an aggregate of a plurality of ceramic particles, and rare earth inclusions containing rare earth components are contained at the grain boundaries between the plurality of ceramic particles, the internal electrode layer contains a first metal component as a magnetic base metal, the sintered electrode layer contains a second metal component as a non-magnetic noble metal, the first-stage plating layer contains the first metal component, and the ceramic layer, the internal electrode layer and the sintered electrode layer are sintered; (B) A step of obtaining ceramic microparticles formed by micronizing the above-mentioned sintered waste, the above-mentioned rare earth inclusions, the above-mentioned internal electrode layer and the above-mentioned first stage plating layer formed by micronizing the first metal microparticles and the above-mentioned sintered electrode layer formed by micronizing the ceramic layer; (C) A step of separating the above-mentioned sintered waste after step (B) into a first separator containing the above-mentioned ceramic microparticles and the above-mentioned first metal microparticles using a magnet; and a step of recovering a second separator containing the above-mentioned ceramic microparticles, the above-mentioned rare earth inclusions and the above-mentioned second metal microparticles; and (H) A step of recovering the above-mentioned first metal component from the above-mentioned first separator after step (C) by electrolytic refining.

[0205] <15> A method for separating and recovering rare earth and metal components from post-firing waste of multilayer ceramic capacitors, comprising the following steps: (A) preparing post-firing waste of multilayer ceramic capacitors, wherein the post-firing waste of multilayer ceramic capacitors comprises a multilayer body including a ceramic layer and an internal electrode layer, a sintered electrode layer disposed on the multilayer body and connected to the internal electrode layer, a first-stage plating layer disposed on the sintered electrode layer, and a second-stage plating layer disposed on the first-stage plating layer as the outermost layer of the multilayer ceramic capacitor. The electrode layer is used as a post-firing waste, wherein the ceramic layer has an aggregate of multiple ceramic particles, and rare earth inclusions containing rare earth elements are contained at the grain boundaries between the multiple ceramic particles; the inner electrode layer contains a first metal component as a magnetic base metal; the sintered electrode layer contains a second metal component as a non-magnetic noble metal; the first-stage plating layer contains the first metal component; the second-stage plating layer contains a third metal component; and the ceramic layer, the inner electrode layer, and the sintered electrode layer are sintered. (K) The step of removing at least the second stage coating from the first stage coating and the second stage coating in the above-mentioned post-firing waste; (B) The step of obtaining ceramic micro-materials formed by micro-removing the ceramic layer, the rare earth inclusions, the first metal micro-materials formed by micro-removing the internal electrode layer and the first stage coating, and the second metal micro-materials formed by micro-removing the sintered electrode layer by micro-removing the above-mentioned post-firing waste by micro-removing waste through step (K); (C) Using a magnet, separating the above-mentioned calcined waste after step (B) into a first separate containing the above-mentioned ceramic microparticles and the above-mentioned first metal microparticles; and a second separate containing the above-mentioned ceramic microparticles, the above-mentioned rare earth inclusions and the above-mentioned second metal microparticles and recovering them; and (H) Recovering the above-mentioned first metal component from the above-mentioned first separate after step (C) by electrolytic refining.

[0206] 10, 10A, 10B: Multilayer ceramic capacitors 12: Laminated body 12a: 1st main side 12b: 2nd main side 12c: First side 12d: Second side view 12e: First end face 12f: Second end face 14: Ceramic layer 14_U: Ceramic layer before firing 16: Internal electrode layer 16_U: Internal electrode layer before firing 16a: First inner electrode layer 16b: Second inner electrode layer 30: External electrode 30a: First external electrode 30b: Second external electrode 32: Burn-in electrode layer 32a: First substrate electrode layer, first sintered electrode layer 32b: Second base electrode layer, second sintered electrode layer 34: Coating 34a: First plating layer 34b: Second plating layer 34a1: First lower plating layer 34a2: First upper coating layer 34b1: Second lower plating layer 34b2: Second upper coating layer 40: Core and Shell 42: Core 44: Shell 50: Grain boundary 60: Electrolytic Refining System 61: Electrolytic cell 61a: Electrolyte 62: Anode 63: Cathode 64: Power Supply 65: Anode Basket 65a: Processing objects BT: Ceramic particles BT1_P: First ceramic powder BT2: Ceramic micro-fine compounds BT2_P: Second ceramic powder Dy_P: Rare earth powder Ni_P: First metal powder x: Height direction y: width direction z: Length direction

Claims

1. A method for separating and recovering rare earth and metal components from sintering waste of multilayer ceramic capacitors, comprising the following steps: (A) preparing sintering waste of multilayer ceramic capacitors, wherein the sintering waste of multilayer ceramic capacitors comprises a multilayer body including a ceramic layer and an internal electrode layer, and a sintered electrode layer disposed on the multilayer body as the outermost layer and connected to the internal electrode layer, wherein the ceramic layer has an aggregate of a plurality of ceramic particles, and rare earth inclusions containing rare earth components are contained at the grain boundaries between the plurality of ceramic particles, the internal electrode layer contains a first metal component as a base metal with magnetic properties, the sintered electrode layer contains a second metal component as a noble metal without magnetic properties, and the ceramic layer, the internal electrode layer and the sintered electrode layer are sintered. (B) A step of obtaining ceramic microparticles formed by micronizing the above-mentioned calcined waste, the above-mentioned rare earth inclusions, the above-mentioned first metal microparticles formed by micronizing the above-mentioned internal electrode layer, and the above-mentioned second metal microparticles formed by micronizing the above-mentioned calcined electrode layer by micronizing the above-mentioned calcined waste; (C) A step of using a magnet to separate the above-mentioned calcined waste after step (B) into a first separate containing the above-mentioned ceramic microparticles and the above-mentioned first metal microparticles, and a second separate containing the above-mentioned ceramic microparticles, the above-mentioned rare earth inclusions, and the above-mentioned second metal microparticles, and recovering them; and (H) A step of recovering the above-mentioned first metal component from the above-mentioned first separate after step (C) by electrolytic refining.

2. The method for separating and recovering rare earth and metal components from the sintering waste of multilayer ceramic capacitors as claimed in claim 1, wherein in step (H) above, the metal powder contents are added in a processed block state, wherein the metal powders are in contact with each other to the extent that current flows during the above electrolytic refining.

3. The method for separating and recovering rare earth and metal components from the sintering waste of multilayer ceramic capacitors as claimed in claim 1, wherein in step (C) above, the micronized sintering waste and an aqueous solvent are mixed in step (B) above to generate a slurry, and then the magnet above is used to recover the first separated product and the second separated product respectively.

4. The method for separating and recovering rare earth and metal components from the sintering waste of multilayer ceramic capacitors as claimed in claim 1, further comprising the following steps: (D) dissolving the second separated product after step (C) in at least one inorganic acid without oxidizing power selected from the group including dilute sulfuric acid and hydrochloric acid, thereby precipitating the ceramic microparticles and the second metal microparticles in the second separated product, and generating a solution containing rare earth components in which the rare earth components in the rare earth contained product are dissolved.

5. The method for separating and recovering rare earth and metal components from the sintering waste of multilayer ceramic capacitors as claimed in claim 4, wherein in step (D) above, the solution containing rare earth components is adjusted to a pH value of 1.5 or higher and a pH value of 2.5 or lower by adding the aforementioned inorganic acid that does not have oxidizing power.

6. The method for separating and recovering rare earth and metal components from the post-firing waste of multilayer ceramic capacitors as claimed in claim 4 or 5, further comprising the following steps: (E) dissolving the ceramic microparticles and the second metal microparticles precipitated in the second separator in ammonia water, thereby precipitating the ceramic microparticles in the second separator and generating a second metal solution containing the second metal component contained in the second metal microparticles.

7. The method for separating and recovering rare earth and metal components from the sintering waste of multilayer ceramic capacitors as claimed in claim 6, wherein in step (E) above, the second metal solution is adjusted to a pH value of 9 or higher and a pH value of 10 or lower by adding the aforementioned ammonia water.

8. The method for separating and recovering rare earth and metal components from the post-firing waste of multilayer ceramic capacitors as claimed in claim 4 or 5, further comprising the following steps: (F) performing solid-liquid separation on the solution containing the rare earth components, which includes the precipitated ceramic microparticles and the undissolved second metal microparticles.

9. The method for separating and recovering rare earth and metal components from the sintering waste of multilayer ceramic capacitors as described in claim 8, further includes, after step (F) above, a rare earth component concentration step for concentrating the rare earth components in the solution containing rare earth components.

10. A method for separating and recovering rare earth and metal components from the sintering waste of multilayer ceramic capacitors, as described in claim 1 or 2, wherein the first metal component is Ni.

11. A method for separating and recovering rare earth and metal components from the sintering waste of multilayer ceramic capacitors, as described in claim 1 or 2, wherein the second metal component is Cu.

12. A method for separating and recovering rare earth and metal components from the sintering waste of multilayer ceramic capacitors, as described in claim 1 or 2, wherein the ceramic particles are BaTiO3.

13. A method for separating and recovering rare earth and metallic components from the sintering waste of multilayer ceramic capacitors as claimed in claim 1 or 2, wherein the rare earth components are at least one of Dy, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb, and Lu.

14. A method for separating and recovering rare earth and metal components from sintering waste of multilayer ceramic capacitors, comprising the following steps: (A) preparing sintering waste of multilayer ceramic capacitors, wherein the sintering waste of multilayer ceramic capacitors comprises a multilayer body including a ceramic layer and an internal electrode layer, a sintered electrode layer disposed on the multilayer body and connected to the internal electrode layer, and a sintered electrode layer disposed on the sintered electrode layer as the outermost first-stage plating layer, wherein the ceramic layer has an aggregate of a plurality of ceramic particles, and rare earth inclusions containing rare earth components are contained at the grain boundaries between the plurality of ceramic particles, the internal electrode layer contains a first metal component as a magnetic base metal, the sintered electrode layer contains a second metal component as a non-magnetic noble metal, the first-stage plating layer contains the first metal component, and the ceramic layer, the internal electrode layer and the sintered electrode layer are sintered. (B) A step of obtaining ceramic microparticles formed by micronizing the above-mentioned post-firing waste, the above-mentioned rare earth inclusions, the above-mentioned internal electrode layer and the above-mentioned first-stage plating layer formed by micronizing the first metal microparticles and the above-mentioned sintered electrode layer formed by micronizing the ceramic layer; (C) A step of using a magnet to separate the above-mentioned post-firing waste after step (B) into a first separate containing the above-mentioned ceramic microparticles and the above-mentioned first metal microparticles, and a second separate containing the above-mentioned ceramic microparticles, the above-mentioned rare earth inclusions and the above-mentioned second metal microparticles, and recovering them; and (H) A step of recovering the above-mentioned first metal component from the above-mentioned first separate after step (C) by electrolytic refining.

15. A method for separating and recovering rare earth and metal components from post-firing waste of multilayer ceramic capacitors, comprising the following steps: (A) preparing post-firing waste of multilayer ceramic capacitors, wherein the post-firing waste of multilayer ceramic capacitors comprises a multilayer body including a ceramic layer and an internal electrode layer, a sintered electrode layer disposed on the multilayer body and connected to the internal electrode layer, a first-stage plating layer disposed on the sintered electrode layer, and a second-stage plating layer disposed on the first-stage plating layer as the outermost layer of the multilayer ceramic capacitor. The sintered electrode layer is used as a post-firing waste after firing, wherein the ceramic layer has an aggregate of a plurality of ceramic particles, and rare earth inclusions containing rare earth elements are contained at the grain boundaries between the plurality of ceramic particles; the inner electrode layer contains a first metal component as a magnetic base metal; the sintered electrode layer contains a second metal component as a non-magnetic noble metal; the first stage plating layer contains the first metal component; the second stage plating layer contains a third metal component; and the ceramic layer, the inner electrode layer, and the sintered electrode layer are sintered. (K) The step of removing at least the second stage coating from the first stage coating and the second stage coating in the above-mentioned post-firing waste; (B) The step of obtaining ceramic micro-materials formed by micro-removing the ceramic layer, the rare earth inclusions, the first metal micro-materials formed by micro-removing the internal electrode layer and the first stage coating, and the second metal micro-materials formed by micro-removing the sintered electrode layer by micro-removing the above-mentioned post-firing waste by micro-removing waste through step (K); (C) Using a magnet, separating the above-mentioned calcined waste after step (B) into a first separate containing the above-mentioned ceramic microparticles and the above-mentioned first metal microparticles, and a second separate containing the above-mentioned ceramic microparticles, the above-mentioned rare earth inclusions and the above-mentioned second metal microparticles, and recovering them; and (H) Recovering the above-mentioned first metal component from the above-mentioned first separate after step (C) by electrolytic refining.

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