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

Abstract

Provided is a method for separating and recovering a rare earth component and a metal component from a post-firing waste. The separation and recovery method includes: a step (A) of preparing a post-firing waste of a laminated ceramic capacitor in which a ceramic layer, an internal electrode layer containing a first metal component having magnetism, and a sintered sintering electrode layer containing a second metal component having no magnetism are sintered; a step (B) of finely pulverizing the post-firing waste; a step (C) of separating and recovering using a magnet into a first separated material containing ceramic fine particles and first metal fine particles and a second separated material containing ceramic fine particles, a rare earth-containing substance, and second metal fine particles; a step (D) of dissolving the second separated material in an inorganic acid having no oxidizing power, precipitating the ceramic fine particles and the second metal fine particles, and generating a rare earth component-containing solution in which a rare earth component in the rare earth-containing substance is dissolved; and a step (E) of dissolving the precipitate in the second separated material in ammonia water, and generating a second metal solution in which the second metal component in the second metal fine particles is dissolved.

Description

Technical Field

[0001] This invention relates to a method for separating and recovering rare earth and metallic components from the post-firing waste of multilayer ceramic capacitors. Background Technology

[0002] As electronic components used in automobiles, mobile phones, and other electronic devices, a large demand for multilayer ceramic capacitors (MLCCs) is foreseeable. A multilayer ceramic capacitor comprises a stack 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, primarily used in the inner electrode layer, and disclose the separation of BaTiO3 contained in the ceramic layer during the Ni recovery process.

[0003] Prior art literature

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2003-253347

[0006] Patent Document 2: Japanese Patent Application Publication No. 2003-268459

[0007] Patent Document 3: Japanese Patent Application Publication No. 2003-277843

[0008] Patent Document 4: Japanese Patent Application Publication No. 2003-277846 Summary of the Invention

[0009] The problem the invention aims to solve

[0010] Here, among the raw materials used in the manufacture of multilayer ceramic capacitors, there are materials that contain not only Ni but also rare earth elements. While patent documents 1-4 disclose the recovery of Ni, the recovery of rare earth elements has not been disclosed. However, it is desirable to be able to recover not only metallic components such as Ni but also rare earth elements.

[0011] Therefore, the main objective of this invention is to provide a method for separating and recovering rare earth and metal components from the waste materials after firing of multilayer ceramic capacitors.

[0012] Technical solutions for solving the problem

[0013] The method for separating and recovering rare earth and metallic components from the post-firing waste of multilayer ceramic capacitors, as disclosed in this invention, comprises:

[0014] Step (A) prepares the post-firing waste of the multilayer ceramic capacitor. The post-firing waste of the multilayer ceramic capacitor has a multilayer comprising a ceramic layer and an inner electrode layer and a sintered electrode layer disposed on the multilayer as the outermost layer and connected to the inner electrode layer. The ceramic layer has an aggregate of multiple ceramic particles and contains rare earth components at the grain boundaries between the multiple ceramic particles. The inner electrode layer contains a first metal component as a magnetic base metal and the sintered electrode layer contains a second metal component as a non-magnetic noble metal. The ceramic layer, the inner electrode layer and the sintered electrode layer are sintered.

[0015] Process (B) involves miniaturizing the waste material after firing to obtain ceramic micro-materials with miniaturized ceramic layers, rare earth inclusions, a first metal micro-material with miniaturized internal electrode layers, and a second metal micro-material with miniaturized sintered electrode layers.

[0016] In process (C), a magnet is used to separate the sintered waste after process (B) into a first separate containing ceramic microparticles and a first metal microparticle, and a second separate containing ceramic microparticles, rare earth inclusions and a second metal microparticle for recycling.

[0017] Step (D) involves dissolving the second isolate following step (C) in at least one non-oxidizing inorganic acid selected from the group consisting of dilute sulfuric acid and hydrochloric acid, thereby precipitating the ceramic microparticles and the second metal microparticles in the second isolate, and generating a rare earth component-containing solution containing the rare earth components dissolved in the rare earth components; and

[0018] In step (E), the ceramic microparticles and the second metal microparticles precipitated in step (D) are dissolved in ammonia water, thereby precipitating the ceramic microparticles in the second separator and generating a second metal solution in which the second metal component contained in the second metal microparticles is dissolved.

[0019] According to the present invention, rare earth components and metallic components can be separated and recovered from post-calcination waste. In particular, as metallic components, a first metallic component contained in the inner electrode layer and a second metallic component contained in the outer electrode can be separated and recovered.

[0020] The method for separating and recovering rare earth and metallic components from the post-firing waste of multilayer ceramic capacitors, as disclosed in this invention, comprises:

[0021] Step (A) prepares the post-firing waste of the multilayer ceramic capacitor. The post-firing waste of the multilayer ceramic capacitor has a multilayer comprising a ceramic layer and an inner electrode layer, a sintered electrode layer disposed on the multilayer and connected to the inner electrode layer, and a first-level plating layer disposed on the sintered electrode layer as the outermost layer. The ceramic layer has an aggregate of multiple ceramic particles, and the grain boundaries between the multiple ceramic particles contain rare earth components containing rare earth elements. 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-level plating layer contains the first metal component. The ceramic layer, the inner electrode layer and the sintered electrode layer are sintered.

[0022] Process (B) involves miniaturizing the waste material after firing to obtain ceramic micro-materials that have been miniaturized into ceramic layers, rare earth inclusions, first metal micro-materials that have been miniaturized into internal electrode layers and first-level plating layers, and second metal micro-materials that have been miniaturized into sintered electrode layers.

[0023] In process (C), a magnet is used to separate the sintered waste after process (B) into a first separate containing ceramic microparticles and a first metal microparticle, and a second separate containing ceramic microparticles, rare earth inclusions and a second metal microparticle for recycling.

[0024] Step (D) involves dissolving the second isolate following step (C) in at least one non-oxidizing inorganic acid selected from the group consisting of dilute sulfuric acid and hydrochloric acid, thereby precipitating the ceramic microparticles and the second metal microparticles in the second isolate, and generating a rare earth component-containing solution containing the rare earth components dissolved in the rare earth components; and

[0025] In step (E), the ceramic microparticles and the second metal microparticles precipitated in step (D) are dissolved in ammonia water, thereby precipitating the ceramic microparticles in the second separator and generating a second metal solution in which the second metal component contained in the second metal microparticles is dissolved.

[0026] According to the present invention, rare earth components and metallic components can be separated and recovered from post-calcination waste. In particular, as metallic components, a first metallic component contained in the inner electrode layer and a second metallic component contained in the outer electrode can be separated and recovered.

[0027] The method for separating and recovering rare earth and metallic components from the post-firing waste of multilayer ceramic capacitors, as disclosed in this invention, comprises:

[0028] Step (A) prepares the post-firing waste of the multilayer ceramic capacitor. The post-firing waste of the multilayer ceramic capacitor has a multilayer comprising a ceramic layer and an inner electrode layer, a sintered electrode layer disposed on the multilayer and connected to the inner electrode layer, a first-level plating layer disposed on the sintered electrode layer, and a second-level plating layer disposed on the first-level plating layer as the outermost layer. 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-level plating layer contains the first metal component. The second-level plating layer contains a third metal component. The ceramic layer, the inner electrode layer, and the sintered electrode layer are sintered.

[0029] Process (K) involves removing at least the second-level plating layer from the first-level plating layer and the second-level plating layer in the post-firing waste.

[0030] In process (B), the calcined waste that has had at least the second-level plating layer removed by process (K) is miniaturized to obtain ceramic miniaturized material with miniaturized ceramic layer, rare earth inclusions, first metal miniaturized material with miniaturized internal electrode layer and first-level plating layer, and second metal miniaturized material with miniaturized calcined electrode layer.

[0031] In process (C), a magnet is used to separate the sintered waste after process (B) into a first separate containing ceramic microparticles and a first metal microparticle, and a second separate containing ceramic microparticles, rare earth inclusions and a second metal microparticle for recycling.

[0032] Step (D) involves dissolving the second isolate following step (C) in at least one non-oxidizing inorganic acid selected from the group consisting of dilute sulfuric acid and hydrochloric acid, thereby precipitating the ceramic microparticles and the second metal microparticles in the second isolate, and generating a rare earth component-containing solution containing the rare earth components dissolved in the rare earth components; and

[0033] In step (E), the ceramic microparticles and the second metal microparticles precipitated in step (D) are dissolved in ammonia water, thereby precipitating the ceramic microparticles in the second separator and generating a second metal solution in which the second metal component contained in the second metal microparticles is dissolved.

[0034] According to the present invention, rare earth components and metallic components can be separated and recovered from post-calcination waste. In particular, as metallic components, a first metallic component contained in the inner electrode layer and a second metallic component contained in the outer electrode can be separated and recovered.

[0035] Invention Effects

[0036] According to the present invention, a method for separating and recovering rare earth components and metal components from the post-firing waste of multilayer ceramic capacitors can be provided.

[0037] The above-described objects, other objects, features, and advantages of the present invention will become clearer from the following detailed description of specific embodiments with reference to the accompanying drawings. Attached Figure Description

[0038] Figure 1 This is a flowchart illustrating a method for separating and recovering rare earth components and metal components from waste materials after firing (firing for attaching electrode layers) of a multilayer ceramic capacitor, according to the first embodiment of the present invention.

[0039] Figure 2 This is a perspective view showing an example of a multilayer ceramic capacitor according to the first embodiment of the present invention.

[0040] Figure 3 yes Figure 2 A cross-sectional view at line III-III.

[0041] Figure 4 This 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 containing the length direction and the stacking direction in a stacked piece.

[0042] Figure 5 yes Figure 3 An enlarged view of the α portion, and a schematic diagram showing the state of each layer after firing for attaching the electrode layer.

[0043] Figure 6 yes Figure 5 A magnified view of part of the ceramic layer.

[0044] Figure 7 This is a cross-sectional view (1) of a multilayer ceramic capacitor according to the second embodiment of the present invention, parallel to a plane including the length direction and the stacking direction.

[0045] Figure 8 This is a cross-sectional view (2) of a multilayer ceramic capacitor according to another embodiment of the present invention, parallel to a plane including the length direction and the stacking direction.

[0046] Figure 9 This is a flowchart illustrating a method for separating and recovering rare earth and metallic components from waste materials after the firing (firing for attaching electrode layers) of multilayer ceramic capacitors, including a coating removal process. Detailed Implementation

[0047] <First Embodiment>

[0048] 1. Separation and recovery methods

[0049] The method for separating and recovering rare earth components and metal components (first metal component and second metal component) from waste after firing (firing for attaching electrode layers) of multilayer ceramic capacitors according to the first embodiment of the present invention will be described.

[0050] Figure 1 This 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 a multilayer ceramic capacitor, according to the first embodiment of the present invention. In the separation and recovery method according to the first embodiment of the present invention, waste material after firing (firing for attaching electrode layers) of the multilayer ceramic capacitor is used as the starting point for separation and recovery. The waste material after firing will be described.

[0051] (1) Waste after firing

[0052] Before explaining the waste after firing, we will first explain the multilayer ceramic capacitor manufactured through the manufacturing process of multilayer ceramic capacitors and the manufacturing process itself.

[0053] (1-1) Multilayer ceramic capacitor

[0054] Figure 2 This is a perspective view showing an example of a multilayer ceramic capacitor according to the first embodiment of the present invention. Figure 3 yes Figure 2 The cross-sectional view at line III-III. Here, as an example of the multilayer ceramic capacitor 10, a two-terminal multilayer ceramic capacitor will be used for illustration.

[0055] like Figure 2 , Figure 3 As shown, the multilayer ceramic capacitor 10 includes, for example, a cuboid multilayer 12 and external electrodes 30 disposed at both ends of the multilayer 12.

[0056] The laminate 12 has a plurality of stacked ceramic layers 14 and a plurality of internal electrode layers 16 stacked on the ceramic layers 14. Furthermore, the laminate 12 has a first main surface 12a and a second main surface 12b opposite each other in the height direction (stacking direction) x, a first side surface 12c and a second side surface 12d opposite each other in the width direction y orthogonal to the height direction x, and a first end surface 12e and a second end surface 12f opposite each other in the length direction z orthogonal to both the height direction x and the width direction y. The ceramic layers 14 and the internal electrode layers 16 are stacked in the height direction x.

[0057] The first internal electrode layer 16a and the second internal electrode layer 16b can, for example, be made of a conductive material containing a magnetic base metal. The magnetic base metal can be an elemental metal or an alloy. Examples of magnetic base metals include Ni and Fe. Furthermore, metals with a higher tendency to ionize than hydrogen are referred to as base metals.

[0058] Ceramic layer 14 has multiple ceramic particles (described later). Figure 5 The BT (also known as ceramic sintered body) is an aggregate of various BTs. Regarding each ceramic particle, for example, it can be formed from a dielectric material as a ceramic material. As such a dielectric material, for example, a dielectric ceramic having a perovskite structure with a perovskite-type compound containing BaTiO3, CaTiO3, SrTiO3, or CaZrO3 as the main component can be used. When the above-mentioned dielectric material is used as the main component, rare earth components are added as additives to the dielectric material according to the desired characteristics of the laminate 12. Examples of added rare earth components 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, for the above-mentioned dielectric material, for example, a dielectric material with a content of less than the main component, such as Mn compound, Fe compound, Cr compound, Co compound, or Ni compound, can also be used. In addition, at least one of Si, Mg, Ba, and Mn can be added to the main components as further additives. However, these by-products and additives may cause a decline in the quality of rare earth components during the separation and recovery of rare earth components, so these by-products and additives can be omitted.

[0059] like Figure 2 , Figure 3 As shown, external electrodes 30 are disposed on the first end face 12e side and the second end face 12f side of the laminate 12.

[0060] 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.

[0061] 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. In this embodiment, 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 among the layers disposed on the multilayer 12.

[0062] The sintered electrode layer 32 may also be formed of 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 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, metals with a lower ionization tendency compared to the hydrogen phase are referred to as noble metals.

[0063] (1-2) Manufacturing method of multilayer ceramic capacitors

[0064] Next, the manufacturing method of the multilayer ceramic capacitor 10 will be described.

[0065] (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 is formed, for example, from a dielectric slurry with BaTiO3 as the main component and Dy as an additive, but is not limited thereto. The conductive paste for the internal electrode layer is formed, for example, with Ni as the main component, but is not limited thereto. The dielectric sheet and the conductive paste for the internal electrode layer contain an adhesive and a solvent. The adhesive and solvent are composed of a resin component, and as the resin component, various known thermosetting resins such as epoxy resin, phenoxy resin, phenolic resin, polyurethane resin, and polyimide resin can be used.

[0066] (Step 2) Then, for example, conductive paste for the inner electrode layer is printed on the dielectric sheet in a given pattern by screen printing, gravure printing, etc. Thus, a dielectric sheet with a pattern of the first inner electrode layer and a dielectric sheet with a pattern of the second inner electrode layer are prepared.

[0067] In addition, regarding the dielectric sheet, a dielectric sheet for the outer layer without the pattern of the internal electrode layer is also prepared.

[0068] An outer layer dielectric sheet with a given number of unprinted internal electrode layer patterns is stacked. A dielectric sheet with a first internal electrode layer pattern and a dielectric sheet with a second internal electrode layer pattern printed are sequentially stacked on top of this outer layer, thereby forming an inner layer portion. A given number of outer layer dielectric sheets with unprinted internal electrode layer patterns are then stacked on this inner layer portion. This forms a laminated sheet having an inner layer and an outer layer. The dielectric sheet is sometimes referred to as an unfired ceramic layer, that is, a ceramic layer before firing the stacked sheets. The pattern of the internal electrode layer is sometimes referred to as an unfired internal electrode layer, that is, an internal electrode layer before firing the stacked sheets.

[0069] (Step 3) Next, the laminated sheets are pressed in the stacking direction by means of isostatic pressing, thereby producing a laminated block.

[0070] (Step 4) Then, the stacked blocks are cut to the given size to cut out stacked pieces. Figure 4 This 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 containing the length direction and the stacking direction of a stacked wafer. Figure 4 The image shows a cross-sectional view of the stacked pieces before the external electrode 30 is formed. Furthermore, Figure 4 The laminated sheets are in their state before degreasing (step 5) and firing (step 6). However, the resin composition of the laminated sheets is not illustrated. Figure 4 As shown, stacked sheets are formed by alternately stacking the unfired internal electrode layer 16_U and the unfired ceramic layer 14_U.

[0071] The stacked small pieces contain the first metal powder as a whole. Figure 4 Ni_P in ceramic powder ( Figure 4 BT1_P, BT2_P, and rare earth powders (in the context of BT1_P, BT2_P) Figure 4 The components include Dy_P, and resin. The first metal powder mainly constitutes the unfired internal electrode layer 16_U. The ceramic powder mainly constitutes the unfired ceramic layer 14_U.

[0072] The first metal powder is, for example, an aggregate of first metal atoms that constitute the first metal component. As mentioned above, the first metal powder can be composed of a conductive material containing a magnetic base metal, which can be an elemental metal or an alloy. Examples of magnetic base metals include, for example, Ni and Fe.

[0073] Ceramic powder is an aggregate of dielectric materials. Examples of dielectric materials, as mentioned earlier, include BaTiO3, CaTiO3, SrTiO3, and CaZrO3. Furthermore, 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.

[0074] Rare earth powders are aggregates of rare earth atoms that constitute rare earth components. Regarding rare earth atoms, as mentioned earlier, at least one of the following can be listed: Dy, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb, and Lu.

[0075] The resin component is an adhesive and solvent used to generate conductive paste for dielectric sheets and internal electrode layers. The adhesive and solvent are composed of 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.

[0076] use Figure 4 The state of the powder in the stacked flakes will be further explained. Figure 4 The schematic diagram shows the state of the various powders contained in the stacked sheets before degreasing (step 5) and firing (step 6). Additionally, in Figure 4 The diagram of the resin components has been omitted. (For example...) Figure 4 As shown, in this embodiment, the unfired ceramic layer 14_U mainly contains the first ceramic powder ( Figure 4 It is composed of BT1_P in the middle. Moreover, in the unfired ceramic layer 14_U, the first ceramic powder and rare earth powder ( Figure 4 The Dy_P in the model are at least partially attached to each other. For example... Figure 4 As shown in the example, the state is such that rare earth powder is mainly attached to the surface of the first ceramic powder, rather than the rare earth powder entering the interior of the first ceramic powder and chemically bonding with it. Furthermore, in this embodiment, the internal electrode layer 16_U before firing mainly contains the first metal powder (…). Figure 4 It is composed of Ni_P. Moreover, in the unfired internal electrode layer 16_U, the first metal powder and the second ceramic powder ( Figure 4 The BT2_P in the model are at least partially attached to each other. For example... Figure 4 As shown in the example, the state is one where the second ceramic powder is mainly attached to the surface of the first metal powder, rather than a state where the second ceramic powder penetrates into the interior of the first metal powder and undergoes chemical bonding. The term "attachment" can also include situations where the first metal powder, ceramic powder, and rare earth powders are partially chemically bonded to each other. Furthermore, chemical bonding refers to a combination where multiple atoms are united through the attraction of positive and negative charges, such as ionic bonding, covalent bonding, or metallic bonding.

[0077] (Step 5)

[0078] Next, the resin component in the stacked small pieces is removed. The removal of the resin component in step 5 is degreasing, a process performed during manufacturing. The degreasing temperature in step 5 is, for example, higher than 800°C but lower than 1000°C.

[0079] (Step 6) Next, the stacked sheets are fired to form the laminate 12. The firing temperature of the stacked sheets depends on the materials of the ceramic layer (which serves as the dielectric) and the internal electrode layer, but is preferably higher than 1000°C and lower than 1400°C. Steps 1 to 6 are the laminate formation steps. The firing in step 6 is sometimes referred to as the firing of the stacked sheets. Through this firing, the unfired stacked sheets become the laminate 12. Furthermore, the unfired internal electrode layer 16_U and the unfired ceramic layer 14_U are fired to form the internal electrode layer 16 and the ceramic layer 14.

[0080] (Step 7) Next, a paste containing multiple second metal powders (e.g., Cu powder) is applied to the first end face 12e and the second end face 12f of the laminate 12 and fired to form a sintered electrode layer 32 serving as the external electrode 30. The second metal powder is, for example, an aggregate of second metal atoms that are the second metal component. Each second metal powder in the sintered electrode layer paste is dispersed individually in the sintered electrode layer paste, or it is dispersed by adhering to other powders containing other second metal powders. That is, in the sintered electrode layer paste, each second metal powder does not chemically bond with other second metal powders or other additives. Moreover, by firing the sintered electrode layer paste, the second metal powders, etc., are brought into a sintered state. The firing temperature of the sintered electrode layer paste is preferably 700°C or higher and 900°C or lower. In addition, the firing in step 7 is sometimes referred to as firing for sintering electrode layers.

[0081] Next, the state of each layer of the stacked ceramic capacitor 10 after firing (step 7) for firing the electrode layer will be described. Figure 5 yes Figure 3 An enlarged view of the α portion, and a schematic diagram showing the state of each layer after firing for attaching the electrode layer. Figure 6 yes Figure 5 A partially enlarged view of the ceramic layer. After the firing of the electrode layer, the multilayer ceramic capacitor 10 is in a sintered state, consisting of the ceramic layer 14, the inner electrode layer 16, and the outer electrode 30.

[0082] In ceramic layer 14, ceramic powder ( Figure 4 BT1_P and BT2_P in the middle are fired, thus as follows Figure 5 The image shows ceramic particles BT in a sintered state. Figure 5 BT in (the text is incomplete and requires further context). Additionally, ceramic powder (the text is incomplete and requires further context). Figure 4For example, BT1_P and BT2_P in step 6 are fired in layers to form fired ceramic particles BT. Sometimes, ceramic particles BT in a sintered state are referred to as sintered ceramic bodies BT. For example, through firing, the contact between ceramic powders evolves from point contact to surface contact. This results in chemical bonding between the ceramic powders, forming integrated ceramic particles BT (sintered ceramic bodies BT). Ceramic particles BT are also sometimes formed by partially chemically bonding ceramic powder with rare earth powders. Figure 5 In the example, ceramic layer 14 comprises an aggregate of multiple ceramic particles BT. Additionally, the first ceramic powder ( Figure 4 Most of the BT1_P in the middle, for example, undergoes firing of stacked small pieces in step 6, thereby forming ceramic layer 14. Furthermore, the first metal powder ( Figure 4 The second ceramic powder of Ni_P (in Figure 4 Most of the BT1_P in the middle, for example, undergoes firing of stacked small pieces in step 6, thereby forming ceramic layer 14. At this time, the second ceramic powder ( Figure 4 Most of the BT1_P in the middle is not substantially bonded to the fired internal electrode layer 16 and is extruded from the fired internal electrode layer 16, and is fired together with the first ceramic powder to form the ceramic layer 14.

[0083] If we further explain the ceramic layer 14, then each ceramic particle BT is composed of Figure 6 The core-shell 40 shown is formed. The core-shell 40 has a core portion 42 containing a central portion of the core-shell 40 and a shell portion 44 covering the surface of the core portion 42. The core portion 42 is mainly formed of ceramic material. The shell portion 44 is formed by introducing rare earth components, such as additives, into the ceramic material. In addition, by-products such as Mn compounds may also be introduced into the shell portion 44. Grain boundaries 50 exist at the boundaries between ceramic particles BT. The grain boundaries 50 contain rare earth components. In the rare earth components, the rare earth components are contained, for example, in the form of oxides. Oxides that are rare earth components can be listed as, for example, dysprosium oxide (Dy2O3). In addition, the rare earth components may also contain, for example, silicon dioxide (SiO2), manganese dioxide (MnO2), etc. Furthermore, the fact that each ceramic particle BT has a core-shell structure has been explained above. However, each ceramic particle BT may also have a structure in which rare earth components, etc., are introduced into the central portion of the ceramic particle BT. Alternatively, ceramic particles BT with this structure and ceramic particles BT with a core-shell structure can be mixed together within the ceramic layer 14.

[0084] In the inner electrode layer 16, the first metal powder ( Figure 4 Ni (P) in the middle is sintered, thus as Figure 5The first metal particle shown is in a sintered state. Figure 5 Ni in it). Additionally, the first metal powder ( Figure 4 The Ni_P in the middle, for example, is formed by firing the stacked small pieces in step (6), thereby forming the fired internal electrode layer 16. Figure 5 In this process, Ni powder, serving as the first metal powder, is sintered to form Ni particles (first metal particles). Sometimes, the first metal particles in a sintered state are referred to as a first metal sintered body. For example, the first metal powder is heated during sintering, thereby transforming the contact between the first metal powders from point contact to surface contact. This results in the bonding between the first metal powders to form an integrated first metal particle (first metal sintered body). Figure 5 In the example, the inner electrode layer 16 contains an aggregate of multiple first metal particles.

[0085] In the sintered electrode layer 32 (outer electrode 30), the second metal powder (e.g., Cu powder) is sintered for the sintered electrode layer, thereby... Figure 5 The second metal particle shown is in a sintered state. Figure 5 Cu in. Figure 5 In this process, 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 referred to as a second metal sintered body. For example, the second metal powder is heated through a sintering process for attaching an electrode layer, thereby transforming the contact between the second metal powders from point contact to surface contact. This results in the bonding between the second metal powders to form an integrated second metal particle (second metal sintered body). Figure 5 In the example, the sintered electrode layer 32 contains an aggregate of multiple second metal particles.

[0086] The multilayer ceramic capacitor 10 is manufactured through the above-described manufacturing process.

[0087] 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.

[0088] (2) Flowchart of the separation and recovery method

[0089] Reference Figure 1 The process of the separation and recovery method according to the first embodiment of the present invention will be described. Figure 1The separation and recovery method includes a common separation and recovery pathway, a rare earth component separation and recovery pathway, a first metal component separation and recovery pathway, and a second metal component separation and recovery pathway. The rare earth component separation and recovery pathway and the first metal component separation and recovery pathway branch off from the common separation and recovery pathway. The second metal component separation and recovery pathway branch off from the rare earth component separation and recovery pathway.

[0090] A common separation and recovery path includes, 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), it branches into a separation and recovery path for rare earth components and a separation and recovery path for the first metal component. The separation and recovery path for rare earth components includes, for example, the dissolution of the second precipitate in step (D), and may also include filtration in step (F) and neutralization in step (G). Furthermore, after filtration in step (F), the separation and recovery path for the second metal component branches off from the separation and recovery path for rare earth components. The separation and recovery path for the second metal component includes, for example, the dissolution of undissolved material in step (E), and may also include filtration in step (H). The separation and recovery path for the first metal component includes, for example, the dissolution of the first precipitate in step (I), and may also include filtration in step (J).

[0091] (Process (A): Preparation of waste after firing)

[0092] In process (A), the waste material after firing (firing for the attached electrode layer) of the multilayer ceramic capacitor is prepared. The waste material after firing is as described above. The waste material after firing includes: a multilayer 12, comprising 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.

[0093] (Process (B): Miniaturization)

[0094] In step (B), the post-firing waste is miniaturized. For example, miniaturization can be achieved by pulverizing the post-firing waste, but this is not a limitation. Pulverization can be performed, for example, by applying a pulverizing force to the object using a vibratory mill, crushing the object, or applying a pulverizing force to the object by impact, but this is not a limitation. Preferably, the post-firing waste is miniaturized to a degree that facilitates separation during the magnetic separation in step (C) described later. By miniaturizing the post-firing waste, it is possible to obtain ceramic micro-materials that have miniaturized the sintered ceramic layer 14, rare earth inclusions in the sintered state, a first metal micro-material that has miniaturized the sintered internal electrode layer 16, and a second metal micro-material that has miniaturized the sintered sintered electrode layer 32. The ceramic micro-materials may contain ceramic materials such as BaTiO3, CaTiO3, SrTiO3, or CaZrO3. Rare earth elements may include, for example, dysprosium oxide (Dy₂O₃), as well as silicon dioxide (SiO₂), manganese dioxide (MnO₂), etc. For example, the first metal micronizer may contain, for example, Ni and Fe as first metal components. For example, the second metal micronizer may contain, for example, Cu as a second metal component. The average particle size of the calcined waste after micronization is not limited. The average particle size can be determined, for example, by using a sieve.

[0095] (Process (C): Magnetic Separation)

[0096] In the magnetic separation process (C), magnets are used to magnetically separate the calcined waste that has been micronized in process (B). In other words, the calcined waste is separated into a first separate and a second separate for recycling through magnetic separation.

[0097] The first isolate contains a first metal micronization ( Figure 1 Ni) and ceramic microstructures ( Figure 1 (BT in the text). The first metal micronized material contains a first metal component that is a magnetic base metal. On the other hand, the ceramic micronized material is not magnetic. Through magnetic separation, the first separated material is separated into magnetic adhering materials. Specifically, in the first separated material, when the magnetic first metal micronized material is separated into magnetic adhering materials, it becomes a state in which non-magnetic ceramic micronized materials are mixed in with the first metal micronized material.

[0098] The second isolate contains a second metal refinement ( Figure 1 Cu in rare earth elements (Cu) Figure 1 Dy2O3 in and ceramic micronization ( Figure 1(BT in the text). The second metal micro-element contains a second metal component that is a non-magnetic noble metal. In addition, the rare earth inclusions and ceramic micro-element are non-magnetic. Therefore, through magnetic separation, the second metal micro-element, rare earth inclusions, and ceramic micro-element are separated into non-magnetic deposits.

[0099] Therefore, through this magnetic separation, the second separated product is removed from the post-calcination waste, and the first separated product containing the first metal micronized material can be separated and recycled as the first metal component. For example, the first metal micronized material is obtained by micronizing Ni (the first metal component) in a sintered state constituting the internal electrode layer 16. Furthermore, in this invention, the separation and recycling of the first metal component includes not only separating and recycling the first metal component itself, but also separating and recycling the first separated product containing the first metal micronized material as the first metal component.

[0100] Furthermore, the first metallic component includes the first metal atom itself, a first metallic component compound that is a reactant of the first metal atom and other atoms, a solution of the first metal atom, and a solution of the first metallic component compound. Moreover, the state of the first metallic component can be any of a liquid state, a solid state, or a mixture of liquid and solid. Furthermore, the first metallic component can be any of an amorphous state, a crystalline state, or a mixture of amorphous and crystalline substances.

[0101] In other words, through this magnetic separation, it is possible to separate and recover the second metal micro-fines and rare earth inclusions from the post-calcination waste after the removal of the first separator.

[0102] In addition, when performing magnetic separation, it is preferable to mix the calcined waste that has been micronized in step (B) with an aqueous solvent such as water to disperse it, thereby setting it to a mixed state, and then use a magnet to separate it.

[0103] If the refined post-firing waste is mixed with an aqueous solvent to form a slurry, it is possible to disperse the ceramic micro-particles, rare earth inclusions, first metal micro-particles, and second metal micro-particles contained in the refined post-firing waste. Therefore, in process (C), it is easy to separate the first and second separated components using a magnet. If the refined post-firing waste is in a dry state, the first and second separated components tend to have a lower dispersion compared to the slurry state. Therefore, for example, when the first separated component is attracted by a magnet, the second separated component may mix into the first separated component and be attracted by the magnet, sometimes making it difficult to separate the first and second separated components.

[0104] (Process (D): Dissolution of the second separated product)

[0105] In step (D), the second precipitate, which was separated and recovered in step (C), is dissolved in a non-oxidizing inorganic acid. This generates a solution containing the rare earth components dissolved in the rare earth components contained in the second precipitate. Therefore, the solution containing the rare earth components can be separated and recovered as a rare earth component. At this time, ceramic microparticles and second metal microparticles in the second precipitate precipitate. The ceramic microparticles react with the non-oxidizing inorganic acid, thus becoming undissolved and precipitating. Furthermore, the second metal microparticles, such as Cu, have a lower ionization tendency compared to the hydrogen ions contained in the non-oxidizing inorganic acid, and therefore do not dissolve in the non-oxidizing inorganic acid. The non-oxidizing inorganic acid is, for example, at least one selected from the group consisting of dilute sulfuric acid and hydrochloric acid.

[0106] Furthermore, as mentioned above, rare earth components are separated and recovered as a solution containing rare earth components. In this invention, the separation and recovery of rare earth components includes not only separating and recovering the rare earth components themselves, but also separating and recovering the solution containing rare earth components as rare earth components. That is, the rare earth components include rare earth atoms themselves, rare earth compound products that have undergone chemical reactions with other atoms, solutions of rare earth atoms, and solutions of rare earth compound products. Furthermore, the rare earth components can be in a liquid state, a solid state, or a mixture of liquid and solid states. Additionally, the rare earth components can be in an amorphous state, a crystalline state, or a mixture of amorphous and crystalline states.

[0107] In step (D), it is preferable to adjust the solution containing rare earth components to a pH of 1.5 or higher and a pH of 2.5 or lower by adding an inorganic acid that does not have oxidizing power.

[0108] By adjusting the pH of the solution containing rare earth components to a level between 1.5 and 2.5 using a non-oxidizing inorganic acid in step (D), the rare earth components in the rare earth contents can be primarily dissolved in the non-oxidizing inorganic acid. Furthermore, if the pH is adjusted to a strong acid compared to the above range, ceramic microparticles may sometimes dissolve in the non-oxidizing inorganic acid; therefore, it is preferable to adjust the pH to the above range. More preferably, the pH of the solution containing rare earth components is adjusted to 2 by adding a non-oxidizing inorganic acid.

[0109] Furthermore, in process (C), when the post-calcination waste in slurry form is magnetically separated, the second separated product 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 components, adjusted to a pH above 1.5 and below 2.5, can also be generated. However, the second separated product after magnetic separation does not need to be in a slurry state; it can also be in a dry state.

[0110] When the ceramic microparticles contained in the second isolate are, for example, BaTiO3, dilute sulfuric acid is preferably used as a non-oxidizing inorganic acid. When dilute sulfuric acid is used, insoluble BaSO4 forms on the surface of the BaTiO3 ceramic microparticles, thus allowing the ceramic microparticles to precipitate. Furthermore, the second metal microparticles, such as Cu, have a lower ionization tendency compared to the hydrogen ions contained in the non-oxidizing inorganic acid, and therefore are insoluble in the non-oxidizing inorganic acid. On the other hand, rare earth powders can be dissolved in dilute sulfuric acid. Specifically, for example, if a second isolate mainly containing Cu, rare earth components such as Dy2O3, and BaTiO3 ceramic microparticles are dissolved in dilute sulfuric acid, BaTiO3 precipitates, and Cu does not dissolve. On the other hand, a solution of dysprosium sulfate (Dy2(SO4)3) is generated as a solution containing rare earth components, in which Dy in the rare earth components dissolves in dilute sulfuric acid.

[0111] Furthermore, as mentioned above, hydrochloric acid, other than dilute sulfuric acid, can be used as a non-oxidizing inorganic acid. However, for example, when hydrochloric acid is used as a non-oxidizing inorganic acid, BaCl2, which is soluble, forms on the surface of BaTiO3, which is a ceramic microstructure. Therefore, it is preferable to precisely adjust the pH of the hydrochloric acid or the like so that the rare earth inclusions dissolve while the ceramic microstructure precipitates and the second metal microstructure remains undissolved.

[0112] (Process (F): Filtration)

[0113] In step (F), the solution containing the precipitated ceramic microparticles and undissolved second metal microparticles, which is generated in step (D), is filtered, thereby performing solid-liquid separation of the undissolved ceramic microparticles, second metal microparticles, and the solution containing rare earth components. Through this solid-liquid separation, the solution containing the undissolved ceramic microparticles and second metal microparticles, which contains rare earth components, can be separated and recovered as rare earth components.

[0114] For example, in step (D), assuming that BaTiO3 is precipitated and the second metal micronized compounds such as Cu are not dissolved, a solution of dysprosium sulfate (Dy2(SO4)3) dissolved in dilute sulfuric acid is generated as a rare earth component. In this case, by filtration in step (F), the dysprosium sulfate solution after removing BaTiO3 and Cu can be separated and recovered as a rare earth component.

[0115] Regarding filtration, filter paper (filter cloth) can be used. The mesh size of the filter paper (filter cloth) is preferably such that undissolved ceramic microparticles and second metal microparticles do not pass through the filter paper (filter cloth).

[0116] Solid-liquid separation can be performed on the solution containing rare earth components, including undissolved ceramic micro-fines and second metal micro-fines, generated in process (D). It is not limited to solid-liquid separation by filtration, and solid-liquid separation can also be performed by appropriately selecting known methods such as decantation and centrifugation. Filtration is preferred.

[0117] (Process (G): Neutralization)

[0118] In step (G), the rare earth components are recovered by neutralizing the solution containing rare earth components obtained in step (F), causing the rare earth components to precipitate. The precipitated rare earth components can be 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 component compounds (e.g., Dy(OH)3, etc.) through neutralization. In this invention, the separation and recovery of rare earth components includes not only separating and recovering the rare earth components themselves, but also separating and recovering rare earth component compounds that have undergone chemical reactions as rare earth components.

[0119] Regarding neutralization, an alkali is used. Examples of alkalis include sodium hydroxide and potassium hydroxide. While the pH range for rare earth element precipitation may change depending on the redox potential, using these alkalis can stabilize the pH range for rare earth element precipitation.

[0120] Furthermore, in the neutralization process of step (G), the rare earth components are recovered by adjusting the pH of the solution containing rare earth components to a level above 6 and below 9. This allows for the efficient separation and recovery of the precipitate obtained through the neutralization reaction as a rare earth component. More preferably, the pH of the solution containing rare earth components is adjusted to 8 by adding an alkali.

[0121] For example, in the filtration process of step (F), after obtaining a dysprosium sulfate solution from which BaTiO3 and Cu have been removed, dysprosium hydroxide (Dy(OH)3) is obtained as a rare earth element compound through neutralization using sodium hydroxide. In other words, since the dysprosium sulfate solution is acidic, neutralization with an alkali allows dysprosium, as a rare earth element, to precipitate as dysprosium hydroxide (Dy(OH)3) and be separated and recovered. Here, by filtering the solution from which the dysprosium sulfate solution has been neutralized with an alkali, dysprosium hydroxide (Dy(OH)3) can be separated and recovered. Besides filtration, known methods such as decantation and centrifugation can also be used.

[0122] Furthermore, there are metallic components (so-called contaminants) that were not separated as the first separate product during the magnetic separation in step (C) and are mixed into the second separate product. Therefore, sometimes the rare earth component solution generated during the dissolution of the second separate product in step (D) contains metallic components that act as contaminants. These metallic components are, for example, Ti, Mn, Ni, etc. Moreover, in step (G), by adding alkali to the solution containing the rare earth component to adjust the pH to, for example, above pH 3 and below pH 5, preferably around pH 4, it is possible to separate and recover Ti and Mn, etc. In this case, Ti precipitates, for example, as Ti(OH)4, and Mn precipitates, for example, as Mn(OH)2. Therefore, by filtering the rare earth component solution adjusted to approximately pH 4, Ti(OH)4 and Mn(OH)2, etc., are recovered.

[0123] Then, alkali is added to the solution containing rare earth components such as Ti and Mn to adjust the pH to above 6 and below 9, preferably around 8, as described above, thereby separating and recovering the rare earth components.

[0124] Then, alkali is added to the solution from which Ti, Mn, rare earth elements, etc., to adjust the pH to, for example, above 9 and below 11, preferably around 10, thereby enabling the separation and recovery of Ni, etc. In this case, Ni precipitates, for example, as Ni(OH)₂. The solution adjusted to approximately pH 10 is then filtered to recover Ni(OH)₂, etc.

[0125] By repeating this process of phased neutralization and filtration, it is possible to separate and recover various components (pollutants and rare earth elements, etc.) contained in the solution containing rare earth elements.

[0126] Furthermore, in the staged neutralization of the rare earth component-containing solution as described above, the solution is neutralized to a pH of 3 or higher and a pH of 5 or lower, preferably to approximately pH 4, before separating the rare earth components. Therefore, contaminants such as Ti and Mn can be removed from the rare earth component-containing solution first. Since contaminants such as Ti and Mn are removed from the rare earth component-containing solution in this way, the separation of rare earth components can be facilitated by using the rare earth component-containing solution in a state where these contaminants have been removed.

[0127] (Process (E): Dissolution of undissolved substances)

[0128] In step (E), the ceramic micro-fines and the second metal micro-fines extracted by filtration in step (F) are dissolved in ammonia. This generates a second metal solution containing the second metal component of the second metal micro-fines. Therefore, the second metal solution can be separated and recovered as the second metal component. At this time, the ceramic micro-fines precipitate.

[0129] Specifically, a second metal micronized compound containing a second metal component such as Cu and a ceramic micronized compound containing BaTiO3 are dissolved in ammonia water. This, for example, allows the production of a compound containing [Cu(NH3)4]. 2+ The second metal solution containing the copper ammonia complex. BaTiO3 precipitates in the second metal solution.

[0130] 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 separating and recovering the second metal component itself, but also separating and recovering the second metal component solution as the second metal component. Here, the second metal component includes the second metal component itself, a second metal component compound that is a reactant of the second metal component with other atoms, 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 of a liquid state, a solid state, or a mixture of liquid and solid. Furthermore, the second metal component can be any of an amorphous state, a crystalline state, or a mixture of amorphous and crystalline states.

[0131] In step (E), it is preferable to adjust the pH of the second metal solution to be above 9 and below 10 by adding ammonia. By adjusting the pH of the second metal solution to be above 9 and below 10 in step (E), the second metal solution can be efficiently separated and recovered as a second metal component. More preferably, the pH of the second metal solution is adjusted to 9.5 by adding ammonia.

[0132] Furthermore, when dissolving the undissolved ceramic micro-particles and the second metal micro-particles removed 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 is the source of ammonia used to form ammonia complexes such as copper-ammonia complexes for the second metal component, such as Cu. In addition, the ammonium salt provides counterions to the ammonia complexes such as copper-ammonia complexes. For example, ammonium salts as ammonium sulfate contribute counterions to [Cu(NH3)4]. 2+ The copper ammonia complex supplies SO4 2- As a counterion. Moreover, even when the concentration of ammonia decreases, salts such as CuSO4 are formed, which inhibit the precipitation of Cu ions.

[0133] (Process (H): Filtration)

[0134] In step (H), the second metal solution containing the precipitated ceramic microparticles generated in step (E) is filtered, thereby performing solid-liquid separation between the precipitated ceramic microparticles and the second metal solution. Through this solid-liquid separation, the second metal solution containing the precipitated ceramic microparticles, after the precipitated ceramic microparticles have been removed, can be separated and recovered as a second metal component.

[0135] For example, in process (E), a second metal solution is generated by dissolving a second metal component, such as Cu, in ammonia water while BaTiO3 is in a precipitated state as the second metal solution. The second metal solution may contain, for example, [Cu(NH3)4]. 2+ The copper-ammonia complex is obtained. In this case, by filtration in process (H), the second metal solution containing the copper-ammonia complex, from which BaTiO3 has been removed, can be separated and recovered as the second metal component.

[0136] Regarding filtration, filter paper (filter cloth) can be used. The mesh size of the filter paper (filter cloth) is preferably such that the precipitated ceramic microparticles do not pass through the filter paper (filter cloth). Furthermore, solid-liquid separation is not limited to filtration, as long as the second metal solution containing the precipitated ceramic microparticles generated in step (E) can be performed. Known methods such as decantation and centrifugation can be appropriately selected for solid-liquid separation. Filtration is more preferred.

[0137] (Process (I): Dissolution of the first separated product)

[0138] In step (I), the first isolate recovered in step (C) is dissolved in an inorganic acid. The first isolate contains a first metal micronized material and a ceramic micronized material. Through the dissolution of the first isolate in the inorganic acid, the ceramic micronized material contained in the first isolate precipitates as undissolved material, and a first metal solution is generated from the first metal micronized material dissolved in the first isolate. At this time, the first metal component contained in the first metal micronized material is separated and recovered as the first metal solution. 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 metal solution as the first metal component. The inorganic acid is, for example, at least one selected from the group consisting of sulfuric acid, nitric acid, and hydrochloric acid. The inorganic acid can be either a non-oxidizing inorganic acid or an oxidizing inorganic acid. Furthermore, in this embodiment, when simply referred to as an inorganic acid, it means that it contains both a non-oxidizing inorganic acid and an oxidizing inorganic acid.

[0139] In step (I), it is preferable to adjust the pH of the first metal solution to be above 1.5 and below 2.5 by adding an inorganic acid.

[0140] By adjusting the pH of the first metal solution to a level between 1.5 and 2.5 using an inorganic acid in step (I), the first metal component in the first metal micronized material can be primarily dissolved in the inorganic acid. Furthermore, if the pH is adjusted to a strong acid compared to the aforementioned range, ceramic micronized materials may sometimes dissolve in the inorganic acid; therefore, it is preferable to adjust the pH to the aforementioned range. More preferably, the pH of the first metal solution is adjusted to 2 by adding an inorganic acid.

[0141] Furthermore, in process (C), when the calcined waste in slurry form is magnetically separated, the first separated product is in a slurry state with a pH of approximately 7. By adding an inorganic acid to this slurry, a first metal solution with a pH adjusted to above 1.5 and below 2.5 can also be generated. However, the first separated product after magnetic separation does not need to be in a slurry state; it can also be in a dried state.

[0142] When the ceramic microparticles contained in the first isolate are, for example, BaTiO3, sulfuric acid is preferably used as the inorganic acid. When sulfuric acid is used, insoluble BaSO4 forms on the surface of the BaTiO3 ceramic microparticles, thus allowing the ceramic microparticles to precipitate. On the other hand, it allows the first metal microparticles, such as Ni, to dissolve in sulfuric acid. Specifically, for example, by dissolving the first isolate, which mainly contains the first metal microparticles of Ni and the ceramic microparticles of BaTiO3, in sulfuric acid, BaTiO3 precipitates, and a nickel sulfate (NiSO4) solution in which Ni is dissolved in sulfuric acid is generated as the first metal solution.

[0143] In addition, as mentioned above, hydrochloric acid, other than sulfuric acid, can also be used as an inorganic acid. However, for example, when hydrochloric acid is used as an inorganic acid, BaCl2, which is soluble, forms on the surface of BaTiO3, which is a ceramic micronization. Therefore, it is preferable to adjust the pH of the hydrochloric acid or the like with good precision so as to precipitate the ceramic micronization and dissolve the first metal micronization.

[0144] (Process (J): Filtration)

[0145] In step (J), the first metal solution containing the precipitated ceramic microparticles generated in step (I) is filtered, thereby performing solid-liquid separation between the precipitated ceramic microparticles and the first metal solution. Through this solid-liquid separation, the first metal solution containing the precipitated ceramic microparticles, from which the precipitated ceramic microparticles have been removed, can be separated and recovered as the first metal component.

[0146] For example, in step (I), BaTiO3 is precipitated and used as the first metal solution to generate a nickel sulfate (NiSO4) solution in which Ni is dissolved in sulfuric acid. In this case, by filtration, a nickel sulfate solution in which BaTiO3 has been removed can be obtained.

[0147] Regarding filtration, filter paper (filter cloth) can be used. The mesh size of the filter paper (filter cloth) is preferably such that the precipitated ceramic microparticles do not pass through the filter paper (filter cloth). Furthermore, solid-liquid separation is not limited to filtration, as long as the first metal solution containing the precipitated ceramic microparticles generated in step (I) can be performed. Known methods such as decantation and centrifugation can be appropriately selected for solid-liquid separation. Filtration is more preferred.

[0148] In addition, it can replace filtration in step (J) or be used in conjunction with filtration for crystallization and neutralization. Furthermore, by treating the first metal solution obtained in the aforementioned filtration, the first metal component can be separated and recovered, for example, as a first metal component compound (e.g., NiSO4, NiCl2, etc.). In this invention, the separation and recovery of the first metal component includes not only separating and recovering the first metal component itself, but also separating and recovering the first metal component compound, which is a reactant of the first metal component, as the first metal component.

[0149] (3) Effects

[0150] According to the separation and recovery method described above, 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 material after firing of the laminated ceramic capacitor. The details will be explained below.

[0151] The inventors of this application have considered the efficient utilization of the various components contained in the waste after firing (firing for attaching electrode layers) of multilayer ceramic capacitors. In the waste after firing, various components are sintered through firing. For example, the inner electrode layer is formed by sintering first metal particles (first metal sintered body) from first metal powder such as Ni. Furthermore, the ceramic layer is formed by sintering ceramic particles (ceramic sintered body) from ceramic powder such as BaTiO3. Furthermore, the outer electrode is formed by sintering second metal particles (second metal sintered body) from second metal powder such as Cu. It has been discovered that even in such a sintered state of the various parts of a multilayer ceramic capacitor, the various components contained in the multilayer ceramic capacitor can be separated and recovered by employing a separation and recovery method.

[0152] Furthermore, by micronizing the post-firing waste in step (B), ceramic micronized materials, rare earth inclusions, first metal micronized materials, and second metal micronized materials can be obtained. Moreover, by using a magnet to separate the micronized post-firing waste in step (C), it is possible to separate it into a first separate and a second separate. The first separate contains ceramic micronized materials and first metal micronized materials. The second separate contains ceramic micronized materials, rare earth inclusions, and second metal micronized materials. Therefore, by separating and recovering the first separate through step (C), the second separate can be removed from the post-firing waste, and the first separate containing the first metal micronized materials can be separated and recovered as the first metal component.

[0153] Then, in step (D), the second separated product is dissolved in a non-oxidizing inorganic acid, thereby generating a solution containing the rare earth components dissolved in the rare earth powder. This allows the rare earth component solution to be separated and recovered as the rare earth component. At this time, ceramic micro-fines and second metal micro-fines in the second separated product precipitate. The ceramic micro-fines react with the non-oxidizing inorganic acid, thus becoming undissolved and precipitating. Furthermore, the second metal micro-fines, such as Cu, have a lower ionization tendency compared to the hydrogen ions contained in the non-oxidizing inorganic acid, and therefore do not dissolve in the non-oxidizing inorganic acid.

[0154] Then, the ceramic micro-fines and the second metal micro-fines from the second separator taken in step (D) are dissolved in ammonia water, thereby generating a second metal solution in which the second metal components such as Cu in the second metal micro-fines are dissolved. Thus, the second metal solution can be separated and recovered as the second metal component. At this time, the ceramic micro-fines in the second separator do not dissolve in ammonia water and precipitate.

[0155] By employing a separation and recovery method comprising steps (C), (D), and (E), rare earth components can be separated and recovered from the refined post-calcination waste as a rare earth component-containing solution, and a second metal solution can be separated and recovered as a second metal component. Furthermore, with each step, the proportion of rare earth components in the material containing rare earth components and the proportion of second metal components in the material containing second metal components increases. Therefore, for example, it is possible to recover rare earth components such as Dy and second metal components such as Cu at high grades.

[0156] Furthermore, the separation and recovery method of the above-described embodiment also includes step (I). In step (I), the first precipitate is dissolved in an inorganic acid, thereby generating a first metal solution in which the first metal component contained in the first metal microparticle is dissolved. Additionally, in step (I), the ceramic microparticles contained in the first precipitate react with the inorganic acid, thereby becoming undissolved and precipitating, thus separating the ceramic microparticles and the first metal component contained in the first precipitate.

[0157] Therefore, by employing a separation and recovery method comprising steps (C) and (I), the first metal solution can be separated and recovered as the first metal component from the refined post-calcination waste. Furthermore, as the material passes through each step, the proportion of the first metal component in the material increases. Thus, for example, it is possible to recover the first metal component, such as Ni, at a high grade.

[0158] As described above, by using the waste from the firing of multilayer ceramic capacitors to separate and recycle the first metal component, the second metal component, and rare earth components, the waste is not discarded as waste, but can be used as a resource, thus reducing the environmental impact.

[0159] 2. Experimental Example

[0160] The following is an example illustrating how metal and rare earth components were recovered from the calcination waste.

[0161] [Example]

[0162] 10g of post-firing waste was prepared. This 10g post-firing waste contained 35% by mass (3.5g) Ni as the first metal component, 7% by mass (0.7g) Cu as the second metal component, 54% by mass (5.4g) ceramic particles (ceramic sintered body) as BaTiO3, 2% by mass (0.2g) Dy as a rare earth component, and 2% by mass (0.2g) contaminants such as Mg, Mn, and SiO2 (Step (A)). The post-firing waste was pulverized and micronized (Step (B)). The micronized post-firing waste was mixed with 100ml of water to prepare a slurry. Magnetic separation was performed on the slurry using a magnet. Through this magnetic separation, 4.5g of the first component and 4.6g of the second component were separated and recovered (Step (C)). Then, 100 ml of water was added to 4.6 g of the second isolate, and 1 mol% sulfuric acid was added little by little to adjust the pH until it reached pH 2. This precipitated the ceramic micro-fines (BaTiO3) and the second metallic micro-fines (Cu) in the second isolate, and dissolved the Dy contained in the rare earth elements in the sulfuric acid solution (Step (D)). The solution containing the precipitated ceramic micro-fines (BaTiO3) and the second metallic micro-fines (Cu) with Dy dissolved in the sulfuric acid solution was filtered to obtain 90 ml of dysprosium sulfate (Dy2(SO4)3) solution (Step (F)). 1 mol% sodium hydroxide solution was added little by little to the 90 ml of dysprosium sulfate solution as a base to adjust the pH until it reached pH 8 (Step (G)). By filtering this solution, 0.1 g of Dy(OH)3 was separated and recovered. Therefore, through this process, approximately 40% of the Dy contained in the calcination waste is recovered.

[0163] Furthermore, 100 ml of water and 2 g of ammonium sulfate were added to the filtrate of the 4.1 g ceramic microparticles (BaTiO3) and the second metal microparticle (Cu) recovered in step (F), and the pH was adjusted little by little by adding 1 mol% ammonia until it reached 9.5. This precipitated the ceramic microparticles (BaTiO3) and dissolved the second metal microparticle (Cu) in the ammonia (step (E)). The solution was then filtered, thereby separating and recovering 90 ml of [Cu(NH3)4]. 2+ Ammonia-copper complex. Therefore, through this process, approximately 60% of the Cu contained in the calcination waste is recovered.

[0164] Furthermore, 100 ml of water was added to the 4.5 g of the first separator recovered in step (C), and 1 mol% sulfuric acid was added little by little to adjust the pH until it reached pH 2. This precipitated the ceramic micro-fines (BaTiO3) in the first separator and dissolved the first metallic micro-fines (Ni) in the sulfuric acid solution (step (I)). The solution with the precipitated ceramic micro-fines (BaTiO3) and dissolved first metallic micro-fines (Ni) in the sulfuric acid solution was filtered to obtain 90 ml of nickel sulfate (Ni(SO4)) solution (step (J)). 1 mol% caustic soda solution was added little by little to the 90 ml nickel sulfate solution as an alkali to adjust the pH until it reached pH 10. This solution was filtered, thereby separating and recovering 4.4 g of Ni(OH)2. Therefore, through this step, approximately 80% of the Ni contained in the calcination waste was recovered.

[0165] [Experimental Results]

[0166] Based on the above experiments, the separation and recycling method described in this embodiment uses the waste from the firing of multilayer ceramic capacitors as the starting material. Through processes such as magnetic separation and leaching using neutralization, high-grade rare earth components such as Dy, Ni, and Cu, as well as the first metal component and the second metal component, can be easily separated and refined.

[0167] <Second Implementation>

[0168] In the first embodiment described above, the external electrode 30 includes a sintered electrode layer 32. Furthermore, the sintered electrode layer 32 is the outermost layer of the stacked ceramic capacitor 10. Figure 3 However, the form of the external electrode 30 is not limited to this. In the second embodiment, the external electrode 30 includes a sintered electrode layer 32 and a plating layer. Moreover, the plating layer is the outermost layer of the stacked ceramic capacitor. Descriptions similar to those in the first embodiment are omitted or simplified.

[0169] Figure 7 This is a cross-sectional view (1) of a multilayer ceramic capacitor according to the second embodiment of the present invention, parallel to a plane including the length direction and the stacking direction. Figure 8 This is a cross-sectional view (2) of a multilayer ceramic capacitor according to another embodiment of the present invention, parallel to a plane including the length direction and the stacking direction.

[0170] The second embodiment relates to a multilayer ceramic capacitor 10A ( Figure 7 ), 10B ( Figure 8The first embodiment includes a laminate 12 identical to that in the first embodiment, and also includes an external electrode 30 disposed on the laminate 12. 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 the outermost layer of the laminated ceramic capacitors 10A and 10B. The structure other than the plating layer 34 is the same as in the first embodiment. The plating layer 34 is formed, for example, comprising at least one selected from Ni, Sn, Cu, Ag, etc. Furthermore, the laminated ceramic capacitor 10 according to the first embodiment does not include a plating layer (…). Figure 3 ).

[0171] The multilayer ceramic capacitors 10A and 10B according to the second embodiment are formed in step 8 after steps (steps 1) to (steps 7) of the first embodiment described above, by depositing a plating layer 34 on the sintered electrode layer 32. In step 8, by performing a plating process, a first plating layer 34a (first lower plating layer 34a1, first upper plating layer 34a2) is formed on the first sintered electrode layer 32a, 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 a roller plating method. During the plating process, either electrolytic plating or electroless plating can be used. However, regarding electroless plating, in order to increase the plating deposition rate, pretreatment using a catalyst or the like is required, which has the disadvantage of complicating the process. Therefore, electrolytic plating is generally preferred.

[0172] The laminated ceramic capacitors 10A and 10B with plating layer 34 according to the second embodiment are also included in the waste after firing (firing for firing the electrode layer), just like the laminated ceramic capacitor 10 according to the first embodiment (sometimes referred to as the laminated ceramic capacitor 10 without plating layer 34). Furthermore, regarding the laminated ceramic capacitors 10A and 10B with plating layer 34, depending on the material constituting the plating layer 34, there are [various factors] that can be introduced into the aforementioned [processes / processes]. Figure 1 The separation and recovery method shown is described below and its application is discussed later. Figure 9 The separation and recovery method shown is applicable. Figure 1 The separation and recycling method does not include the step of removing the plating layer 34, but in Figure 9 The separation and recycling method includes a step (step (K)) to remove the plating layer 34.

[0173] Furthermore, the plating layer 34 can be formed from a single plating layer ( Figure 7 It can also be formed by stacking multiple layers of plating. Figure 8The following describes the multilayer ceramic capacitor 10A with a single-layer plating layer 34 and the multilayer ceramic capacitor 10B with a multilayer plating layer 34. Furthermore, for each of the multilayer ceramic capacitors 10A and 10B, a method for separating and recovering rare earth components and metal components from the post-firing waste will be described.

[0174] 1. Multilayer ceramic capacitor containing a single-layer plating layer

[0175] (1) Structure

[0176] exist Figure 7 In the illustrated multilayer ceramic capacitor 10A, 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 of a single layer. Figure 7 In this example, the plating layer 34 includes a first lower plating layer (first first-level plating layer) 34a1 and a second lower plating layer 34b1 (second first-level 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. Moreover, the first lower plating layer 34a1 and the second lower plating layer 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.

[0177] (2) Separation and recovery methods

[0178] (2-1) Overview of Separation and Recovery Methods

[0179] The multilayer ceramic capacitor 10A having the plated layer 34 is included in the waste after firing (firing for attaching the electrode layer), similar to that in the first embodiment. Therefore, the multilayer ceramic capacitor 10A having the plated layer 34 can be used in the process described in the first embodiment. Figure 1 The separation and recycling method. That is, in the preparation of post-firing waste in process (A), it is possible to prepare a multilayer ceramic capacitor 10A with a plating layer 34 as post-firing waste. Then, by passing through... Figure 1 The separation and recovery method described herein enables the separation and recovery of the first metal component, the second metal component, and the rare earth component from the multilayer ceramic capacitor 10A having a plating layer 34.

[0180] However, it is also possible to recover the first metal component, the second metal component, and the rare earth component from the multilayer ceramic capacitor 10A after removing the plating layer 34 of the multilayer ceramic capacitor 10A. Figure 9This is a flowchart illustrating a method for separating and recovering rare earth and metallic components from waste generated after the firing (firing for the electrode layer) of multilayer ceramic capacitors, including a plating removal process. Figure 9 In the separation and recovery methods, with Figure 1 Compared to the separation and recycling method, the process (K) between the preparation of waste after firing in process (A) and the micronization in process (B) includes a plating removal process (K) to remove plating layer 34. Figure 9 The separation and recycling method, besides including process (K), is similar to... Figure 1 The separation and recovery methods are the same.

[0181] When separating and recovering various components from a multilayer ceramic capacitor 10A with a plating layer 34, it is important to consider whether to use a process that does not include plating removal. Figure 1 The separation and recovery method still uses a process that includes coating removal. Figure 9 Separation and recycling methods, for example, can distinguish them as shown below, but this is just one example.

[0182] (2-2) Using a separation and recovery method that does not include a coating removal process ( Figure 1 )

[0183] In the multilayer ceramic capacitor 10A having a plating layer 34, the metal composition of both the first lower plating layer 34a1 and the second lower plating layer 34b1 is the same as at least one of the first metal composition of the internal electrode layer 16 and the second metal composition of the sintered electrode layer 32. In this case, the multilayer ceramic capacitor 10A having the plating layer 34 is prepared as... Figure 1 The waste from the firing process (A) is processed through... Figure 1 The separation and recovery method shown in step (B) is further processed in subsequent steps. For example, if both the first lower plating layer 34a1 and the second lower plating layer 34b1 contain a first metal component, the first metal component of plating layer 34 can be separated and recovered together with the first metal component contained in the inner electrode layer 16. Furthermore, for example, if both the first lower plating layer 34a1 and the second lower plating layer 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. Additionally, rare earth components can be separated and recovered from the ceramic layer 14.

[0184] Furthermore, specific examples will be given for illustration. For instance, as an example, suppose that both the first lower plating layer 34a1 and the second lower plating layer 34b1 are plating layers with Ni as the main component. Furthermore, suppose that the internal electrode layer 16 contains Ni as the first metal component. In this case, a multilayer ceramic capacitor 10A is prepared as follows: Figure 1 The waste from the firing process (A). Then, through... Figure 1 In the separation and recovery method, from step (B) onwards, Ni as the first metal component can be separated and recovered from the first lower plating layer 34a1, the second lower plating layer 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.

[0185] Furthermore, for example, let's assume that both the first lower plating layer 34a1 and the second lower plating layer 34b1 are plating layers with Cu as the main component. Also, let's assume that the sintered electrode layer 32 contains Cu as a second metal component. In this case, a multilayer ceramic capacitor 10A is prepared with the first lower plating layer 34a1 and the second lower plating layer 34b1 still in place. Figure 1 The waste from the firing process (A). Then, through... Figure 1 In the separation and recovery method, from step (B) onwards, Cu, as the second metal component, can be separated and recovered from the first lower plating layer 34a1, the second lower plating layer 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.

[0186] (2-3) Separation and recycling methods including coating removal processes ( Figure 9 )

[0187] In the multilayer ceramic capacitor 10A having a plating layer 34, the metal composition of both the first lower plating layer 34a1 and the second lower plating layer 34b1 is different from either the first metal composition of the internal electrode layer 16 or the second metal composition of the sintered electrode layer 32. That is, the metal composition (third metal composition) of the first lower plating layer 34a1 and the second lower plating layer 34b1 is different from either the first or the second metal composition. In this case, the multilayer ceramic capacitor 10A having the plating layer 34 is prepared as... Figure 9 The waste from firing in process (A). Then, the first lower plating layer 34a1 and the second lower plating layer 34b1 are removed by plating removal in process (K). Then, the multilayer ceramic capacitor 10A with the plating layers 34 removed is then... Figure 9The separation and recovery method shown in step (B) is further processed in subsequent steps. As a result, 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 the plating layer 34 has been removed.

[0188] Furthermore, specific examples will be given for illustration. For instance, suppose that both the first lower plating layer 34a1 and the second lower plating layer 34b1 are plating layers with Sn (an example of a third metal component) as the main component. Furthermore, suppose that the inner 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 having plating layers 34 is prepared as... Figure 9 The waste material after firing in process (A). Then, in Figure 9 In process (K), the first lower plating layer 34a1 and the second lower plating layer 34b1, which are mainly composed of Sn, are removed. The first lower plating layer 34a1 and the second lower plating layer 34b1, which are mainly composed of Sn, can be removed by immersing the multilayer ceramic capacitor 10A having the plating layer 34 in an alkaline solution other than ammonia, such as sodium hydroxide or potassium hydroxide. In this case, the sintered electrode layer 32, which is mainly composed of Cu, is exposed to the alkaline solution because the plating layer 34 is removed. However, the sintered electrode layer 32, which is mainly composed of Cu, is not easily corroded by the alkaline solution. Here, the alkaline solution other than ammonia is adjusted to approximately pH 12. Then, by passing through… Figure 9 The separation and recovery method, from step (B) onwards, enables the separation and recovery of 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.

[0189] In the above process, the Sn-based plating layer 34 is removed using an alkaline solution other than ammonia. However, the Sn-based plating layer 34 can also be removed using acidic solutions that do not have oxidizing power, such as hydrochloric acid or dilute sulfuric acid. In this case, the Cu-based sintered electrode layer 32 is exposed to the acidic solution because the plating layer 34 is removed. 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, for example.

[0190] Furthermore, even if the metal components contained in both the first lower plating layer 34a1 and the second lower plating layer 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 having plating layers 34 can still be prepared as... Figure 9The waste material after firing in process (A). Then, the first lower plating layer 34a1 and the second lower plating layer 34b1 can also be removed by plating removal in process (K).

[0191] For example, suppose that both the first lower plating layer 34a1 and the second lower plating layer 34b1 are plating layers with Ni as the main component. Furthermore, 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 having plating layers 34 is prepared as... Figure 9 The waste material after firing in process (A). Then, in Figure 9 In process (K), the first lower plating layer 34a1 and the second lower plating layer 34b1, which are mainly composed of Ni, are removed. The first lower plating layer 34a1 and the second lower plating layer 34b1, which are mainly composed of Ni, can be removed by immersing the multilayer ceramic capacitor 10A having the plating layer 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 because the plating layer 34 is removed. 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. Then, by passing through... Figure 9 The separation and recovery method, from step (B) onwards, enables the separation and recovery of 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.

[0192] 2. Multilayer ceramic capacitors containing multiple plating layers

[0193] (1) Structure

[0194] exist Figure 8 In the multilayer ceramic capacitor 10B shown, 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 of multiple plating layers. Figure 8In this example, the plating layer 34 is formed by two plating layers. Specifically, the plating layer 34 includes a first lower plating layer (first first-level plating layer) 34a1 and a second lower plating layer (second first-level plating layer) 34b1, a first upper plating layer (first second-level plating layer) 34a2 and a second upper plating layer (second second-level 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 among the layers disposed on the laminate 12.

[0195] The multilayer ceramic capacitor 10B having the plating layer 34 is formed after the steps (step 1) to (step 7) of the first embodiment described above, by step (step 8) of depositing the plating layer 34 on the sintered electrode layer 32. In step (step 8), by performing the plating process, a first lower plating layer 34a1 and a first upper plating layer 34a2 are sequentially formed on the first sintered electrode layer 32a, and a second upper plating layer 34b2 on the second lower plating layer 34b1 is sequentially formed on the second sintered electrode layer 32b.

[0196] (2) Separation and recovery methods

[0197] (2-1) Overview of Separation and Recovery Methods

[0198] The multilayer ceramic capacitor 10B having the plated layer 34 is included in the waste after firing (firing for attaching the electrode layer), similar to that in the first embodiment. Therefore, the multilayer ceramic capacitor 10B having the plated layer 34 can be used in the process described in the first embodiment. Figure 1 The separation and recycling method. That is, in the preparation of post-firing waste in process (A), it is possible to prepare a multilayer ceramic capacitor 10B with a plating layer 34 as post-firing waste. Then, by passing through... Figure 1 The separation and recovery method described herein enables the separation and recovery of the first metal component, the second metal component, and the rare earth component from the multilayer ceramic capacitor 10B having a plating layer 34.

[0199] However, it is also possible to recover the first metal component, the second metal component, and the rare earth component from the multilayer ceramic capacitor 10B after removing the plating layer 34 of the multilayer ceramic capacitor 10B.

[0200] When separating and recovering various components from a multilayer ceramic capacitor 10B having a plating layer 34, it is important to consider whether to use a process that does not include plating removal. Figure 1 The separation and recovery method still uses a process that includes coating removal. Figure 9 Separation and recycling methods, for example, can distinguish them as shown below, but this is just one example.

[0201] (2-2) Using a separation and recovery method that does not include a coating removal process ( Figure 1 )

[0202] In the multilayer ceramic capacitor 10B having a plating layer 34, the metal composition of the first lower plating layer 34a1, the second lower plating layer 34b1, the first upper plating layer 34a2, and the second upper plating layer 34b2 is assumed to be the same as at least one of the first metal composition of the internal electrode layer 16 and the second metal composition of the sintered electrode layer 32. In this case, the multilayer ceramic capacitor 10B having the plating layer 34 is prepared as... Figure 1 The waste from the firing process (A) is processed through... Figure 1 The separation and recovery method shown is used for processing. For example, the metal composition of the first lower plating layer 34a1 and the second lower plating layer 34b1 may be the same as the first metal composition contained in the inner electrode layer 16. Furthermore, the metal composition of the first upper plating layer 34a2 and the second upper plating layer 34b2 may be the same as the second metal composition contained in the sintered electrode layer 32. Alternatively, for example, the metal composition of the first lower plating layer 34a1 and the second lower plating layer 34b1 may be the same as the second metal composition contained in the sintered electrode layer 32. Furthermore, the metal composition of the first upper plating layer 34a2 and the second upper plating layer 34b2 may 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. In addition, rare earth components can be separated and recovered from the ceramic layer 14.

[0203] Furthermore, specific examples will be given for illustration. For instance, suppose the first lower plating layer 34a1 and the second lower plating layer 34b1 are plating layers with Ni (or Cu) as the main component. Also suppose the first upper plating layer 34a2 and the second upper plating layer 34b2 are plating layers with Cu (or Ni) as the main component. Furthermore, suppose the internal electrode layer 16 contains Ni as the first metal component. Furthermore, suppose the sintered electrode layer 32 contains Cu as the second metal component. In this case, the multilayer ceramic capacitor 10B is prepared as follows: The first lower plating layer 34a1, the second lower plating layer 34b1, and the first upper plating layer 34a2 and the second upper plating layer 34b2 are not removed. Figure 1The waste from the firing process (A). Then, through... Figure 1 In the separation and recovery method, from step (B) onwards, Ni as the first metal component and Cu as the second metal component can be separated and recovered from the first lower plating layer 34a1, the second lower plating layer 34b1, the first upper plating layer 34a2, the second upper plating layer 34b2, the internal electrode layer 16, and the sintered electrode layer 32. Additionally, rare earth components can be separated and recovered from the ceramic layer 14.

[0204] (2-3) Separation and recycling methods including coating removal processes ( Figure 9 )

[0205] As an example, in the multilayer ceramic capacitor 10B having a plating layer 34, the metal composition (third metal composition) of the first lower plating layer 34a1, the second lower plating layer 34b1, the first upper plating layer 34a2, and the second upper plating layer 34b2 is different from either the first metal composition of the internal electrode layer 16 or the second metal composition of the sintered electrode layer 32. In this case, the multilayer ceramic capacitor 10B having the plating layer 34 is prepared as... Figure 9 The waste from firing in process (A). Then, the first lower plating layer 34a1, the second lower plating layer 34b1, the first upper plating layer 34a2, and the second upper plating layer 34b2 are removed by plating removal in process (K). Then, the multilayer ceramic capacitor 10B with the plating layers 34 removed is processed by... Figure 9 The separation and recovery method shown in step (B) is further processed in subsequent steps. As a result, 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 the plating layer 34 has been removed.

[0206] Furthermore, as another example, in the multilayer ceramic capacitor 10B having a plating layer 34, the third metal component contained in the first upper plating layer 34a2 and the second upper plating layer 34b2 is different from any of the first metal component contained in the inner electrode layer 16 and the second metal component contained in the sintered electrode layer 32. On the other hand, the metal component contained in the first lower plating layer 34a1 and the second lower plating layer 34b1 is the same as any of the first metal component contained in the inner electrode layer 16 and the second metal component contained in the sintered electrode layer 32. In this case, the multilayer ceramic capacitor 10B having the plating layer 34 is prepared as... Figure 9The waste material after firing in process (A). Then, the first upper plating layer 34a2 and the second upper plating layer 34b2 are removed by plating removal in process (K). Then, the multilayer ceramic capacitor 10B with the first upper plating layer 34a2 and the second upper plating layer 34b2 removed is then processed. Figure 9 The separation and recovery method shown in step (B) is further processed in subsequent steps. Thus, the metal components (first or second metal components) contained in the first lower plating layer 34a1 and the second lower plating layer 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 the first upper plating layer 34a2 and the second upper plating layer 34b2 have been removed.

[0207] Furthermore, another example will be given to illustrate the above example. For instance, suppose the first upper plating layer 34a2 and the second upper plating layer 34b2 contain plating layers whose main metal component is Sn (an example of a third metal component). Furthermore, suppose the first lower plating layer 34a1 and the second lower plating layer 34b1 contain plating layers whose main metal component is Ni (or Cu). Furthermore, suppose 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 having plating layers 34 is prepared as... Figure 9 The waste material after firing in process (A). Then, in Figure 9 In process (K), the first upper plating layer 34a2 and the second upper plating layer 34b2, which are mainly composed of Sn, are removed. The first upper plating layer 34a2 and the second upper plating layer 34b2, which are mainly composed of Sn, can be removed by immersing the multilayer ceramic capacitor 10B having the plating layer 34 in an alkaline solution other than ammonia, such as sodium hydroxide or potassium hydroxide. In this case, the first lower plating layer 34a1 and the second lower plating layer 34b1, which are mainly composed of Ni (or Cu), are exposed to the alkaline solution because the first upper plating layer 34a2 and the second upper plating layer 34b2 have been removed. However, the first lower plating layer 34a1 and the second lower plating layer 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, alkaline solutions other than ammonia are adjusted to approximately pH 12. Then, through... Figure 9In the subsequent steps of the separation and recovery method (B), Ni as the first metal component and Cu as the second metal component can be separated and recovered from the first lower plating layer 34a1, the second lower plating layer 34b1, the internal electrode layer 16, and the sintered electrode layer 32. In addition, rare earth components can be separated and recovered from the ceramic layer 14.

[0208] In another specific example described above, only the first upper plating layer 34a2 and the second upper plating layer 34b2 are removed in process (K). However, it is also possible to remove both the first upper plating layer 34a2, the second upper plating layer 34b2, and the first lower plating layer 34a1 and the second lower plating layer 34b1. For example, suppose that the metal composition of the first upper plating layer 34a2 and the second upper plating layer 34b2 is Sn (an example of a third metal composition). Furthermore, suppose that the metal composition of the first lower plating layer 34a1 and the second lower plating layer 34b1 is not Cu-based, but Ni-based. Furthermore, 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 having plating layers 34 is prepared as... Figure 9 The waste material after firing in process (A). Then, in Figure 9 In process (K), the first upper plating layer 34a2 and the second upper plating layer 34b2, which are mainly composed of Sn, and the first lower plating layer 34a1 and the second lower plating layer 34b1, which are mainly composed of Ni, are removed. The first upper plating layer 34a2 and the second upper plating layer 34b2, which are mainly composed of Sn, and the first lower plating layer 34a1 and the second lower plating layer 34b1, which are mainly composed of Ni, can be removed by immersing the multilayer ceramic capacitor 10B having the plating layer 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 because the plating layer 34 is removed. 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. Then, by passing through Figure 9 In the subsequent steps of the separation and recovery method (B), 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. In addition, rare earth components can be separated and recovered from the ceramic layer 14.

[0209] In the above, the first upper plating layer 34a2 and the second upper plating layer 34b2, which are mainly composed of Sn, and the first lower plating layer 34a1 and the second lower plating layer 34b1, which are mainly composed of Ni, are removed in one step by an acidic solution that does not have oxidizing power. However, they can also be removed sequentially. First, the first upper plating layer 34a2 and the second upper plating layer 34b2, which are mainly composed of Sn, are removed by immersing the multilayer ceramic capacitor 10B in an alkaline solution other than ammonia (e.g., about pH 12), such as sodium hydroxide or potassium hydroxide. Then, the first lower plating layer 34a1 and the second lower plating layer 34b1, which are mainly composed of Ni, are removed by immersing the multilayer ceramic capacitor 10B in an acidic solution that does not have oxidizing power, such as hydrochloric acid or dilute sulfuric acid (e.g., about pH 2). Then, by passing through... Figure 9 In the subsequent steps of the separation and recovery method (B), 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. In addition, rare earth components can be separated and recovered from the ceramic layer 14.

[0210] 3. Effects

[0211] Similar to the first embodiment, the multilayer ceramic capacitors 10A and 10B according to the second embodiment, which have a plating layer 34, can also be obtained through... Figure 1 or Figure 9 The separation and recovery method shown separates and recovers 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. Furthermore, by employing a separation and recovery method suitable for separating and recovering metal components from the plating layer 34, it is sometimes possible to recover both the first and second metal components from the plating layer 34.

[0212] Furthermore, as described above, the embodiments of the present invention are disclosed in the above description, but the present invention is not limited thereto.

[0213] That is, various changes can be made to the above-described embodiments regarding mechanism, shape, material, quantity, position or configuration without departing from the technical concept and scope of the present invention, and these are included in the present invention.

[0214] <Other variations>

[0215] (1) Generation of slurry using water-based solvents in process (B)

[0216] In the first and second embodiments described above, the post-calcination waste was pulverized and micronized in step (B). However, as long as the post-calcination waste can be micronized, it is also possible to micronize the post-calcination waste into a dispersed slurry state using a solvent (e.g., an aqueous solvent) together with or instead of the micronization in step (B) (especially micronization by pulverization). Here, micronization in which the post-calcination waste and solvent are mixed to form a slurry is called wet micronization. Furthermore, in wet micronization, micronization in which the post-calcination waste and solvent are pulverized is particularly called wet pulverization. In addition, water can be used as an aqueous solvent, for example.

[0217] Furthermore, in the first and second embodiments described above, during the magnetic separation in step (C), the calcined waste that has been micronized in step (B) can be mixed with an aqueous solvent such as water and dispersed to form a slurry. However, if, as described above, the calcined waste is formed into a slurry using an aqueous solvent in conjunction with or instead of the micronization in step (B), then the calcined waste in the slurry state can be magnetically separated in step (C). In other words, the effort of generating a slurry state during the magnetic separation in step (C) can be eliminated.

[0218] Alternatively, organic solvents can be used to prepare the calcination waste into a slurry. However, if organic solvents are used to prepare the calcination waste into a slurry, 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 prepare the calcination waste into a slurry.

[0219] (2) Other examples of waste contained in the calcination process

[0220] In the first and second embodiments described above, the post-firing waste refers to the waste generated after firing (step 7) for firing the electrode layer. However, the post-firing waste is not limited to this. The post-firing waste may also include waste generated before firing for firing the electrode layer, which is then fed into the process. Figure 1 , Figure 9 The separation and recycling method involves calcining the waste. In this case, the calcination is preferably carried out at the calcination temperature used in the calcination of the electrode layer.

[0221] Waste generated before firing for the electrode layer can be exemplified by the waste discharged in steps (1) to (6). Furthermore, waste generated before firing for the electrode layer can also include waste generated after the electrode layer paste is applied to the laminate 12 in step (7) but before firing for the electrode layer. Specifically, waste generated before firing for the electrode layer can include, for example, waste from dielectric paste in step (1), waste from conductive paste for the internal electrode layer, waste from dielectric sheets with the internal electrode layer pattern formed in step (2), dielectric sheets without the internal electrode layer pattern, excess laminated blocks such as scraps from the laminated blocks discharged after cutting in step (4), waste from cut laminated pieces, waste from degreasing in step (5), and waste from firing laminated pieces in step (6).

[0222] (3) Other laminated ceramic capacitors that discharge waste after firing

[0223] In the first and second embodiments described above, a two-terminal multilayer ceramic capacitor having two terminals, a first external electrode 30a and a second external electrode 30b, was described as the manufactured multilayer ceramic capacitor. However, the application scope of the present invention is not limited to the waste material after firing of two-terminal multilayer ceramic capacitors. The present invention is applicable to the waste material after firing of multilayer ceramic capacitors having an internal electrode layer containing a first metal component such as Ni, an external 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 waste material after firing of three-terminal multilayer ceramic capacitors.

[0224] For example, a three-terminal multilayer ceramic capacitor has the same multilayer body 12 and first to fourth external electrodes as described in the first and second embodiments. The internal electrode layer 16 has a first internal electrode layer extending to a first end face 12e and a second end face 12f, and a second internal electrode layer extending 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. A 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 they may consist of a sintered electrode layer and a plating layer.

[0225] (4) Filtering for process (F)

[0226] If the second separated product is dissolved in a non-oxidizing inorganic acid in step (D), the ceramic microparticles contained in the second separated product react with the non-oxidizing inorganic acid, thus becoming undissolved and precipitating. Furthermore, the second metal microparticles, such as Cu, have a lower ionization tendency compared to the hydrogen ions contained in the non-oxidizing inorganic acid, and therefore do not dissolve in the non-oxidizing inorganic acid. On the other hand, the rare earth components in the rare earth-containing product dissolve to form a rare earth-containing solution. This rare earth-containing solution containing undissolved matter can also be recovered as a rare earth component. In this case, the solid-liquid separation step (F), such as filtration, can be omitted.

[0227] (5) Omission of neutralization in process (G)

[0228] In the first and second embodiments described above, during the dissolution of the second separated product 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.

[0229] (6) Omission of various processing steps in process (I) and process (J)

[0230] In the first and second embodiments described above, during the magnetic separation in step (C), the first separated product containing the first metal micronized material can be separated and recovered as the first metal component. Therefore, steps (I) and (J) can be omitted. Furthermore, during the dissolution of the first separated product in step (I), the first metal solution can be separated and recovered as the first metal component. Therefore, the filtration in step (J) can be omitted.

[0231] (7) Other methods for separating and recovering rare earth components

[0232] In the first and second embodiments described above, rare earth compounds such as Dy(OH)3 are separated and recovered as rare earth components during the neutralization process in step (G). However, the separation and recovery of rare earth components is not limited to this. For example, although this is just one example, rare earth components can be recovered as follows.

[0233] (a)

[0234] The rare earth component compound obtained by neutralization in process (G) is heat-treated to generate an oxide, which can then be recycled as a rare earth component.

[0235] For example, if the rare earth component compound obtained after neutralization in process (G) is Dy(OH)3, dysprosium oxide (Dy2O3) can be recovered as a rare earth component by heat treatment of Dy(OH)3.

[0236] (b)

[0237] The rare earth element compound obtained by neutralization in step (G) is dissolved in hydrochloric acid to generate chloride, thereby enabling the chloride to be recovered as a rare earth element.

[0238] For example, if the rare earth component compound obtained after neutralization in step (G) is Dy(OH)3, dysprosium chloride (DyCl3) solution is generated by dissolving Dy(OH)3 in hydrochloric acid. The solvent is evaporated by distillation of the dysprosium chloride solution, thereby allowing dysprosium chloride hexahydrate (DyCl3·6H2O) to be recovered as a rare earth component.

[0239] (c)

[0240] Furthermore, similar to (b) above, Dy(OH)3, a rare earth element compound obtained after neutralization in step (G), is dissolved in hydrochloric acid to generate a dysprosium chloride solution. Then, through further refining, high-purity rare earth elements can be recovered.

[0241] For example, a dysprosium chloride solution generated as described above can be refined by solvent extraction, thereby recovering a high-purity dysprosium chloride solution as a rare earth component. Solvent extraction is a separation and refining method that utilizes the partitioning of solutes, causing a solute dissolved in one of two immiscible liquid phases, oil and water, to move to the other. Other methods besides solvent extraction include, for example, ion exchange resin methods.

[0242] (d)

[0243] Furthermore, high-purity dysprosium oxide (Dy2O3) can be recovered from a 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 it, high-purity dysprosium oxalate hexahydrate (Dy2(C2O4)3·6H2O) is recovered. By heat-treating this high-purity dysprosium oxalate hexahydrate, high-purity dysprosium oxide (Dy2O3) can be recovered as a rare earth component.

[0244] (e)

[0245] Furthermore, high-purity dysprosium chloride hexahydrate can be recovered from a high-purity dysprosium chloride solution obtained by solvent extraction as described in (c) above. In this case, for example, the high-purity dysprosium chloride hexahydrate is recovered by evaporating the solvent through distillation to remove the high-purity dysprosium chloride solution.

[0246] (f) State of rare earth components

[0247] The recovered rare earth components can 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 can be any of the following states: amorphous, crystalline, or a mixture of amorphous and crystalline.

[0248] (8) Other methods for separation and recovery of the first metal component

[0249] In the first and second embodiments described above, during the dissolution of the first separator in step (I), the first metal micronized material is dissolved in an inorganic acid. Then, the first metal solution is separated and recovered as the first metal component. Furthermore, in the subsequent filtration step (J), the first metal solution containing the precipitated ceramic micronized material is filtered, thereby removing the ceramic micronized material and separating and recovering it as the first metal component. However, the separation and recovery of the first metal component is not limited to this. For example, although this is just one example, the first metal component can be recovered as follows.

[0250] (a)

[0251] By crystallizing the first metal solution, the first metal component compound can be recovered as the first metal component.

[0252] For example, if the first metal solution obtained after dissolving the first metal micronized material in step (I) is a nickel sulfate (NiSO4) solution, by crystallizing and filtering the nickel sulfate solution, nickel sulfate hexahydrate (NiSO4·6H2O) can be recovered as the first metal component.

[0253] (b)

[0254] By refining the first metal solution obtained after dissolving the first metal micronized material in process (I), it is possible to recover the first metal component in high purity.

[0255] For example, nickel sulfate (NiSO4) solution, which is the first metal solution, can be refined by ion exchange resin method, solvent extraction method, etc., and high-purity nickel sulfate solution can be recovered as the first metal component.

[0256] (c)

[0257] The high-purity nickel sulfate solution recovered in (b) above is crystallized and filtered, thereby enabling the recovery of nickel sulfate hexahydrate (NiSO4·6H2O) as the first metal component.

[0258] (d)

[0259] By refining the first metal solution obtained after dissolving the first metal micronized material in step (I) using a method different from that described in (b), it is possible to recover the first metal component in high purity.

[0260] For example, high-purity Ni can be precipitated from a nickel sulfate solution, which is the first metal solution, by means of electrolytic precipitation or other methods, thereby enabling its recovery as the first metal component.

[0261] (e)

[0262] By processing the high-purity Ni recovered in step (d) above, nickel chloride hexahydrate (NiCl2·6H2O) can be recovered as the first metal component. For example, by dissolving the high-purity Ni recovered in step (d) above 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.

[0263] (f)

[0264] The first metal solution obtained after dissolving the first metal micronized material in step (I) is neutralized to generate chloride, thereby enabling the chloride to be recovered as the first metal component.

[0265] For example, a nickel sulfate solution, which serves as the first metal solution, is adjusted and neutralized to, for example, approximately pH 10 (pH above 9 and below pH 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) can be separated and recovered, for example, by filtration. Furthermore, by dissolving the nickel hydroxide in hydrochloric acid, a nickel chloride (NiCl₂) solution is generated. The nickel chloride solution is then distilled to evaporate the solvent, thereby allowing nickel chloride hexahydrate (NiCl₂·6H₂O) to be recovered as the first metal component.

[0266] (g) The state of the first metallic component

[0267] The recovered metallic components can be in any of the following states: liquid, solid, or a mixture of liquid and solid. Furthermore, the crystal lattice of the metallic components can be any of the following states: amorphous, crystalline, or a mixture of amorphous and crystalline.

[0268] (9) Other manufacturing processes of multilayer ceramic capacitors

[0269] In the first and second embodiments described above, the manufacturing method of the multilayer ceramic capacitor 10 sequentially includes (step 3) forming a multilayer block, (step 4) cutting it into multilayer pieces, (step 5) degreasing, (step 6) firing the multilayer pieces, and (step 7) applying a paste for sintering the electrode layer and firing. However, the manufacturing method of the multilayer ceramic capacitor 10 is not limited to this. For example, sometimes an unfired multilayer piece before degreasing in step 5 and before firing (firing of the multilayer piece) in step 6 is coated with a paste for sintering the electrode layer, and then degreasing and firing of the electrode layer are performed. That is, first, an electrode layer paste containing Ni, glass components, resin components, etc., is applied to the multilayer piece before degreasing in step 5. Then, the multilayer piece coated with the electrode layer paste is degreased, and then firing for sintering the electrode layer is performed. The degreasing temperature is preferably higher than 800°C and lower than 1000°C. The firing temperature for firing the electrode layer is preferably higher than 1000°C and lower than 1400°C. These processes are performed after cutting into stacked pieces in step 4 of the manufacturing method described above and before the plating process in step 8. Moreover, in these processes, the firing of the stacked pieces in step 6 and the firing of the electrode layer paste in step 7 are performed in a single firing.

[0270] <1>

[0271] A method for separating and recovering rare earth and metallic components from post-firing waste of multilayer ceramic capacitors, comprising:

[0272] Step (A): Prepare the post-firing waste of the multilayer ceramic capacitor. The post-firing waste of the multilayer ceramic capacitor has a multilayer comprising a ceramic layer and an inner electrode layer, and a sintered electrode layer disposed on the multilayer as the outermost layer and connected to the inner electrode layer. The ceramic layer has an aggregate of multiple ceramic particles, and the grain boundaries between the multiple ceramic particles contain rare earth components containing rare earth elements. The inner electrode layer contains a first metal component as a magnetic base metal, and the sintered electrode layer contains a second metal component as a non-magnetic noble metal. The ceramic layer, the inner electrode layer, and the sintered electrode layer are sintered.

[0273] Step (B) involves miniaturizing the post-firing waste to obtain ceramic micro-materials that have miniaturized the ceramic layer, the rare earth inclusions, a first metal micro-material that has miniaturized the internal electrode layer, and a second metal micro-material that has miniaturized the sintered electrode layer.

[0274] In step (C), a magnet is used 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, the rare earth inclusions, and the second metal microparticles for recycling.

[0275] Step (D) involves dissolving the second isolate after step (C) in at least one non-oxidizing inorganic acid selected from the group consisting of dilute sulfuric acid and hydrochloric acid, thereby precipitating the ceramic microparticles and the second metal microparticles in the second isolate and generating a rare earth component-containing solution in which the rare earth components are dissolved; and

[0276] Step (E) involves dissolving the ceramic microparticles and the second metal microparticles precipitated in the second separator in step (D) in ammonia water, thereby precipitating the ceramic microparticles in the second separator and generating a second metal solution in which the second metal component contained in the second metal microparticles is dissolved.

[0277] <2>

[0278] According to the method for separating and recovering rare earth and metal components from the sintering waste of multilayer ceramic capacitors as described in <1>, wherein,

[0279] It also includes: step (I), which involves dissolving the first separator after step (C) in at least one inorganic acid selected from the group consisting of sulfuric acid, nitric acid and hydrochloric acid, thereby precipitating the ceramic microparticles in the first separator and generating a first metal solution in which the first metal component contained in the first metal microparticles in the first separator is dissolved.

[0280] <3>

[0281] According to the method for separating and recovering rare earth and metallic components from the post-firing waste of multilayer ceramic capacitors as described in <1> or <2>, wherein,

[0282] In step (C), the calcined waste that has been micronized in step (B) is mixed with an aqueous solvent to generate a slurry, and then the magnet is used to recover the first and second separated materials respectively.

[0283] <4>

[0284] The method for separating and recovering rare earth and metallic components from the post-firing waste of multilayer ceramic capacitors according to any one of <1> to <3>, wherein,

[0285] In step (D), the solution containing the rare earth components is adjusted to a pH of 1.5 or higher and a pH of 2.5 or lower by adding the inorganic acid that does not have oxidizing power.

[0286] <5>

[0287] The method for separating and recovering rare earth and metallic components from the post-firing waste of multilayer ceramic capacitors according to any of <1> to <4>, wherein,

[0288] In step (E), the second metal solution is adjusted to a pH of 9 or higher and a pH of 10 or lower by adding the ammonia water.

[0289] <6>

[0290] The method for separating and recovering rare earth and metallic components from the post-firing waste of multilayer ceramic capacitors according to any one of <1> to <5>, wherein,

[0291] The first metallic component is Ni.

[0292] <7>

[0293] The method for separating and recovering rare earth and metallic components from the post-firing waste of multilayer ceramic capacitors according to any one of <1> to <6>, wherein,

[0294] The second metallic component is Cu.

[0295] <8>

[0296] The method for separating and recovering rare earth and metallic components from the post-firing waste of multilayer ceramic capacitors according to any of <1> to <7>, wherein,

[0297] The ceramic particles are BaTiO3.

[0298] <9>

[0299] The method for separating and recovering rare earth and metallic components from the post-firing waste of multilayer ceramic capacitors according to any of <1> to <8>, wherein...

[0300] The rare earth element is at least one of Dy, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb, and Lu.

[0301] <10>

[0302] A method for separating and recovering rare earth and metallic components from post-firing waste of multilayer ceramic capacitors, comprising:

[0303] Step (A) involves preparing the post-firing waste of a multilayer ceramic capacitor. The post-firing waste of the multilayer ceramic capacitor comprises a laminate containing a ceramic layer and an inner electrode layer, a sintered electrode layer disposed on the laminate and connected to the inner electrode layer, and a first-stage plating layer disposed on the sintered electrode layer as the outermost layer. The ceramic layer has an aggregate of multiple ceramic particles, and the grain boundaries between the multiple ceramic particles contain rare earth inclusions containing rare earth elements. The inner electrode layer contains a first metal component that is a magnetic base metal, and the sintered electrode layer contains a second metal component that is a non-magnetic noble metal. The first-stage plating layer contains the first metal component. The ceramic layer, the inner electrode layer, and the sintered electrode layer are sintered.

[0304] Step (B) involves miniaturizing the post-firing waste to obtain ceramic micro-materials that have miniaturized the ceramic layer, the rare earth inclusions, a first metal micro-material that has miniaturized the internal electrode layer and the first-level plating layer, and a second metal micro-material that has miniaturized the sintered electrode layer.

[0305] In step (C), a magnet is used 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, the rare earth inclusions, and the second metal microparticles for recycling.

[0306] Step (D) involves dissolving the second isolate after step (C) in at least one non-oxidizing inorganic acid selected from the group consisting of dilute sulfuric acid and hydrochloric acid, thereby precipitating the ceramic microparticles and the second metal microparticles in the second isolate and generating a rare earth component-containing solution in which the rare earth components are dissolved; and

[0307] Step (E) involves dissolving the ceramic microparticles and the second metal microparticles precipitated in the second separator in step (D) in ammonia water, thereby precipitating the ceramic microparticles in the second separator and generating a second metal solution in which the second metal component contained in the second metal microparticles is dissolved.

[0308] <11>

[0309] A method for separating and recovering rare earth and metallic components from post-firing waste of multilayer ceramic capacitors, comprising:

[0310] Step (A): Preparing the post-firing waste of a multilayer ceramic capacitor, the post-firing waste of the multilayer ceramic capacitor comprising a laminate including a ceramic layer and an inner electrode layer, a sintered electrode layer disposed on the laminate and connected to the inner electrode layer, a first-level plating layer disposed on the sintered electrode layer, and a second-level plating layer disposed on the first-level plating layer as the outermost layer, the ceramic layer having an aggregate of multiple ceramic particles, the grain boundaries between the multiple ceramic particles containing rare earth elements, the inner electrode layer containing a first metal component as a magnetic base metal, the sintered electrode layer containing a second metal component as a non-magnetic noble metal, the first-level plating layer containing the first metal component, the second-level plating layer containing a third metal component, the ceramic layer, the inner electrode layer, and the sintered electrode layer being sintered.

[0311] Process (K) involves removing at least the second-level plating layer from the first-level plating layer and the second-level plating layer in the post-firing waste;

[0312] Step (B) refines the sintered waste that has at least had the second-level plating layer removed by step (K), thereby obtaining ceramic micronized material that has been refined into ceramic layer, rare earth inclusions, first metal micronized material that has been refined into internal electrode layer and first-level plating layer, and second metal micronized material that has been refined into sintered electrode layer.

[0313] In step (C), a magnet is used 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, the rare earth inclusions, and the second metal microparticles for recycling.

[0314] Step (D) involves dissolving the second isolate after step (C) in at least one non-oxidizing inorganic acid selected from the group consisting of dilute sulfuric acid and hydrochloric acid, thereby precipitating the ceramic microparticles and the second metal microparticles in the second isolate and generating a rare earth component-containing solution in which the rare earth components are dissolved; and

[0315] Step (E) involves dissolving the ceramic microparticles and the second metal microparticles precipitated in the second separator in step (D) in ammonia water, thereby precipitating the ceramic microparticles in the second separator and generating a second metal solution in which the second metal component contained in the second metal microparticles is dissolved.

[0316] Explanation of reference numerals in the attached figures

[0317] 10: Multilayer ceramic capacitors;

[0318] 12: Layered body;

[0319] 12a: 1st main side;

[0320] 12b: 2nd main side;

[0321] 12c: First side view;

[0322] 12d: Second side view;

[0323] 12e: First end face;

[0324] 12f: Second end face;

[0325] 14: Ceramic layer;

[0326] 14_U: The ceramic layer before firing;

[0327] 16: Internal electrode layer;

[0328] 16_U: Internal electrode layer before firing;

[0329] 16a: First internal electrode layer;

[0330] 16b: Second internal electrode layer;

[0331] 30: External electrode;

[0332] 30a: First external electrode;

[0333] 30b: Second external electrode;

[0334] 32: Electrode layer sintered;

[0335] 32a: First sintered electrode layer;

[0336] 32b: Second sintered electrode layer;

[0337] 34: Plating layer;

[0338] 34a: First plating layer;

[0339] 34b: Second plating layer;

[0340] 34a1: First lower plating layer;

[0341] 34a2: First upper plating layer;

[0342] 34b1: Second lower plating layer;

[0343] 34b2: Second upper plating layer;

[0344] x: height direction;

[0345] y: width direction;

[0346] z: Length direction.

Claims

1. A method for separating and recovering rare earth and metallic components from post-firing waste of multilayer ceramic capacitors, comprising: Step (A): Prepare the post-firing waste of the multilayer ceramic capacitor. The post-firing waste of the multilayer ceramic capacitor has a multilayer comprising a ceramic layer and an inner electrode layer, and a sintered electrode layer disposed on the multilayer as the outermost layer and connected to the inner electrode layer. The ceramic layer has an aggregate of multiple ceramic particles, and the grain boundaries between the multiple ceramic particles contain rare earth components containing rare earth elements. The inner electrode layer contains a first metal component as a magnetic base metal, and the sintered electrode layer contains a second metal component as a non-magnetic noble metal. The ceramic layer, the inner electrode layer, and the sintered electrode layer are sintered. Step (B) involves miniaturizing the post-firing waste to obtain ceramic micro-materials that have miniaturized the ceramic layer, the rare earth inclusions, a first metal micro-material that has miniaturized the internal electrode layer, and a second metal micro-material that has miniaturized the sintered electrode layer. In step (C), a magnet is used 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, the rare earth inclusions, and the second metal microparticles for recycling. Step (D) involves dissolving the second isolate after step (C) in at least one non-oxidizing inorganic acid selected from the group consisting of dilute sulfuric acid and hydrochloric acid, thereby precipitating the ceramic microparticles and the second metal microparticles in the second isolate and generating a rare earth component-containing solution in which the rare earth components are dissolved; and Step (E) involves dissolving the ceramic microparticles and the second metal microparticles precipitated in the second separator in step (D) in ammonia water, thereby precipitating the ceramic microparticles in the second separator and generating a second metal solution in which the second metal component contained in the second metal microparticles is dissolved.

2. The method for separating and recovering rare earth components and metallic components from the post-firing waste of multilayer ceramic capacitors according to claim 1, wherein, It also includes: step (I), which involves dissolving the first separator after step (C) in at least one inorganic acid selected from the group consisting of sulfuric acid, nitric acid and hydrochloric acid, thereby precipitating the ceramic microparticles in the first separator and generating a first metal solution in which the first metal component contained in the first metal microparticles in the first separator is dissolved.

3. The method for separating and recovering rare earth components and metallic components from the post-firing waste of multilayer ceramic capacitors according to claim 1 or 2, wherein, In step (C), the calcined waste that has been micronized in step (B) is mixed with an aqueous solvent to generate a slurry, and then the magnet is used to recover the first and second separated materials respectively.

4. The method for separating and recovering rare earth components and metallic components from the post-firing waste of multilayer ceramic capacitors according to any one of claims 1 to 3, wherein, In step (D), the solution containing the rare earth components is adjusted to a pH of 1.5 or higher and a pH of 2.5 or lower by adding the inorganic acid that does not have oxidizing power.

5. The method for separating and recovering rare earth components and metallic components from the post-firing waste of multilayer ceramic capacitors according to any one of claims 1 to 4, wherein, In step (E), the second metal solution is adjusted to a pH of 9 or higher and a pH of 10 or lower by adding the ammonia water.

6. The method for separating and recovering rare earth components and metallic components from the post-firing waste of multilayer ceramic capacitors according to any one of claims 1 to 5, wherein, The first metallic component is Ni.

7. The method for separating and recovering rare earth components and metallic components from the post-firing waste of multilayer ceramic capacitors according to any one of claims 1 to 6, wherein, The second metallic component is Cu.

8. The method for separating and recovering rare earth components and metallic components from the post-firing waste of multilayer ceramic capacitors according to any one of claims 1 to 7, wherein, The ceramic particles are BaTiO3.

9. The method for separating and recovering rare earth components and metallic components from the post-firing waste of multilayer ceramic capacitors according to any one of claims 1 to 8, 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.

10. A method for separating and recovering rare earth and metallic components from post-firing waste of multilayer ceramic capacitors, comprising: Step (A) involves preparing the post-firing waste of a multilayer ceramic capacitor. The post-firing waste of the multilayer ceramic capacitor comprises a laminate containing a ceramic layer and an inner electrode layer, a sintered electrode layer disposed on the laminate and connected to the inner electrode layer, and a first-stage plating layer disposed on the sintered electrode layer as the outermost layer. The ceramic layer has an aggregate of multiple ceramic particles, and the grain boundaries between the multiple ceramic particles contain rare earth inclusions containing rare earth elements. The inner electrode layer contains a first metal component that is a magnetic base metal, and the sintered electrode layer contains a second metal component that is a non-magnetic noble metal. The first-stage plating layer contains the first metal component. The ceramic layer, the inner electrode layer, and the sintered electrode layer are sintered. Step (B) involves miniaturizing the post-firing waste to obtain ceramic micro-materials that have miniaturized the ceramic layer, the rare earth inclusions, a first metal micro-material that has miniaturized the internal electrode layer and the first-level plating layer, and a second metal micro-material that has miniaturized the sintered electrode layer. In step (C), a magnet is used 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, the rare earth inclusions, and the second metal microparticles for recycling. Step (D) involves dissolving the second isolate after step (C) in at least one non-oxidizing inorganic acid selected from the group consisting of dilute sulfuric acid and hydrochloric acid, thereby precipitating the ceramic microparticles and the second metal microparticles in the second isolate and generating a rare earth component-containing solution in which the rare earth components are dissolved; and Step (E) involves dissolving the ceramic microparticles and the second metal microparticles precipitated in the second separator in step (D) in ammonia water, thereby precipitating the ceramic microparticles in the second separator and generating a second metal solution in which the second metal component contained in the second metal microparticles is dissolved.

11. A method for separating and recovering rare earth and metallic components from post-firing waste of multilayer ceramic capacitors, comprising: Step (A): Preparing the post-firing waste of a multilayer ceramic capacitor, the post-firing waste of the multilayer ceramic capacitor comprising a laminate including a ceramic layer and an inner electrode layer, a sintered electrode layer disposed on the laminate and connected to the inner electrode layer, a first-level plating layer disposed on the sintered electrode layer, and a second-level plating layer disposed on the first-level plating layer as the outermost layer, the ceramic layer having an aggregate of multiple ceramic particles, the grain boundaries between the multiple ceramic particles containing rare earth elements, the inner electrode layer containing a first metal component as a magnetic base metal, the sintered electrode layer containing a second metal component as a non-magnetic noble metal, the first-level plating layer containing the first metal component, the second-level plating layer containing a third metal component, the ceramic layer, the inner electrode layer, and the sintered electrode layer being sintered. Process (K) involves removing at least the second-level plating layer from the first-level plating layer and the second-level plating layer in the post-firing waste; Step (B) refines the sintered waste that has at least had the second-level plating layer removed by step (K), thereby obtaining ceramic micronized material that has been refined into ceramic layer, rare earth inclusions, first metal micronized material that has been refined into internal electrode layer and first-level plating layer, and second metal micronized material that has been refined into sintered electrode layer. In step (C), a magnet is used 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, the rare earth inclusions, and the second metal microparticles for recycling. Step (D) involves dissolving the second isolate after step (C) in at least one non-oxidizing inorganic acid selected from the group consisting of dilute sulfuric acid and hydrochloric acid, thereby precipitating the ceramic microparticles and the second metal microparticles in the second isolate and generating a rare earth component-containing solution in which the rare earth components are dissolved; and Step (E) involves dissolving the ceramic microparticles and the second metal microparticles precipitated in the second separator in step (D) in ammonia water, thereby precipitating the ceramic microparticles in the second separator and generating a second metal solution in which the second metal component contained in the second metal microparticles is dissolved.

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