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

Abstract

The present invention provides a method for separating and recovering rare earth components and metal components from post-firing waste.　This separation and recovery method comprises: (A) a step for preparing post-firing waste of a multilayer ceramic capacitor in which a ceramic layer, an internal electrode layer containing a magnetic first metal component, and a fired electrode layer containing a non-magnetic second metal component are sintered; (B) a step for pulverizing the post-firing waste; (C) a step for separating and recovering, using a magnet, a first isolate containing a ceramic pulverized product and a first metal pulverized product, and a second isolate containing a ceramic pulverized product, a rare earth-containing product, and a second metal pulverized product; and (H) a step for recovering the first metal component from the first isolate after step (C) by electrolytic refining.

Description

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

[0001] The present invention relates to a method for separating and recovering rare earth elements and metal elements from post-sintering waste of multilayer ceramic capacitors.

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

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

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

[0005] SUMMARY OF THE INVENTION Therefore, a primary object of the present invention is to provide a method for separating and recovering rare earth elements and metal elements from post-sintering waste of multilayer ceramic capacitors.

[0006] The method for separating and recovering rare earth components and metal components from post-sintering waste of multilayer ceramic capacitors according to the present invention includes: (A) a step of preparing post-sintering waste of multilayer ceramic capacitors, the post-sintering waste being post-sintering waste for fired electrode layers of the multilayer ceramic capacitor, the post-sintering waste comprising a laminate including ceramic layers and internal electrode layers, and fired electrode layers disposed on the laminate as outermost layers and connected to the internal electrode layers, the ceramic layers comprising aggregates of a plurality of ceramic particles, rare earth-containing materials containing rare earth components being contained in grain boundaries between the plurality of ceramic particles, the internal electrode layers comprising a first metal component which is a magnetic base metal, the fired electrode layers comprising a second metal component which is a non-magnetic noble metal, and the ceramic layers, the internal electrode layers, and the fired electrode layers being sintered; (B) a step of pulverizing the post-sintering waste to obtain a ceramic pulverized material in which the ceramic layers are pulverized, the rare earth-containing material, a first metal pulverized material in which the internal electrode layers are pulverized, and a second metal pulverized material in which the fired electrode layers are pulverized; (C) using a magnet to separate and recover the fired waste after step (B) into a first separated material containing the ceramic fine particles and the first metal fine particles, and a second separated material containing the ceramic fine particles, the rare earth-containing material, and the second metal fine particles; and (H) recovering the first metal component from the first separated material after step (C) by electrolytic refining.

[0007] According to this invention, rare earth elements and metal elements can be separated and recovered from the post-sintering waste. In particular, as the metal elements, a first metal element contained in the internal electrode layer can be separated and recovered. Also, a second metal element contained in the external electrode can be separated and recovered as a second separated product.

[0008] The method for separating and recovering rare earth components and metal components from post-sintering waste of multilayer ceramic capacitors according to the present invention includes: (A) a step of preparing post-sintering waste of a multilayer ceramic capacitor, the post-sintering waste being for fired electrode layers of the multilayer ceramic capacitor, the post-sintering waste comprising: a laminate including ceramic layers and internal electrode layers; fired electrode layers disposed on the laminate and connected to the internal electrode layers; and a first-stage plating layer disposed on the fired electrode layers as an outermost layer, the ceramic layers comprising aggregates of a plurality of ceramic particles, with rare earth-containing materials containing rare earth components being contained in grain boundaries between the plurality of ceramic particles; the internal electrode layers comprising a first metal component which is a magnetic base metal; the fired electrode layers comprising a second metal component which is a non-magnetic noble metal; the first-stage plating layer comprising the first metal component; and the ceramic layers, the internal electrode layers, and the fired electrode layers being sintered; (B) A step of micronizing the fired waste to obtain a ceramic micronized product in which the ceramic layer has been micronized, a rare earth-containing material, a first metal micronized product in which the internal electrode layer and the first-stage plating layer have been micronized, and a second metal micronized product in which the baked electrode layer has been micronized; (C) A step of using a magnet to separate and recover the fired waste after step (B) into a first separated product containing the ceramic micronized product and the first metal micronized product, and a second separated product containing the ceramic micronized product, the rare earth-containing material, and the second metal micronized product; and (H) A step of recovering the first metal component from the first separated product after step (C) by electrolytic refining.

[0009] According to this invention, rare earth elements and metal elements can be separated and recovered from the post-sintering waste. In particular, as the metal elements, a first metal element contained in the internal electrode layer can be separated and recovered. Also, a second metal element contained in the external electrode can be separated and recovered as a second separated product.

[0010] The method for separating and recovering rare earth components and metal components from post-sintering waste of multilayer ceramic capacitors according to the present invention includes: (A) a step of preparing post-sintering waste of a multilayer ceramic capacitor, the post-sintering waste being for fired electrode layers of the multilayer ceramic capacitor, the post-sintering waste comprising: a laminate including ceramic layers and internal electrode layers; fired electrode layers disposed on the laminate and connected to the internal electrode layers; a first-stage plating layer disposed on the fired electrode layers; and a second-stage plating layer disposed on the first-stage plating layer as an outermost layer, the ceramic layers comprising aggregates of a plurality of ceramic particles, and rare earth-containing materials containing rare earth components are contained in grain boundaries between the plurality of ceramic particles; the internal electrode layers comprising a first metal component which is a magnetic base metal; the fired electrode layers comprising a second metal component which is a non-magnetic noble metal; the first-stage plating layer comprising the first metal component; and the second-stage plating layer comprising a third metal component, the ceramic layers, the internal electrode layers, and the fired electrode layers being sintered; (K) removing at least the second-stage plating layer from the fired waste, of the first-stage plating layer and the second-stage plating layer; (B) micronizing the fired waste from which at least the second-stage plating layer has been removed by passing it through step (K) to obtain a ceramic micronized product in which the ceramic layer has been micronized, a rare earth-containing material, a first metal micronized product in which the internal electrode layer and the first-stage plating layer have been micronized, and a second metal micronized product in which the baked electrode layer has been micronized; (C) using a magnet to separate and recover the fired waste after passing through step (B) into a first separated product containing the ceramic micronized product and the first metal micronized product, and a second separated product containing the ceramic micronized product, the rare earth-containing material, and the second metal micronized product; and (H) recovering the first metal component from the first separated product after passing through step (C) by electrolytic refining.

[0011] According to this invention, rare earth elements and metal elements can be separated and recovered from the post-sintering waste. In particular, as the metal elements, a first metal element contained in the internal electrode layer can be separated and recovered. Also, a second metal element contained in the external electrode can be separated and recovered as a second separated product.

[0012] According to the present invention, it is possible to provide a method for separating and recovering rare earth elements and metal elements from post-sintering waste of multilayer ceramic capacitors.

[0013] The above and other objects, features, and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments of the present invention, which proceeds with reference to the accompanying drawings.

[0014] 5 is a flow diagram showing a method for separating and recovering rare earth components and metal components from waste after firing of a multilayer ceramic capacitor (firing for fired electrode layers) according to an embodiment of the present invention. FIG. 6 is a configuration diagram of an electrolytic refining system. FIG. 7 is an external perspective view showing an example of a multilayer ceramic capacitor according to an embodiment of the present invention. FIG. 8 is a cross-sectional view taken along line III-III in FIG. 2 when the multilayer ceramic capacitor includes fired electrode layers as the outermost layers. FIG. 9 is a schematic diagram showing the state of ceramic layers and internal electrode layers in a multilayer chip before firing, in a cross section parallel to a plane including the length direction and stacking direction. FIG. 10 is an enlarged view of portion α in FIG. 12, showing the state of each layer after firing for fired electrode layers. FIG. 11 is a partial enlarged view of the ceramic layer in FIG. 13. FIG. 14 is a cross-sectional view (1) parallel to a plane including the length direction and stacking direction of a multilayer ceramic capacitor including a plating layer as the outermost layer according to an embodiment of the present invention. FIG. 15 is a cross-sectional view (2) parallel to a plane including the length direction and stacking direction of another aspect of a multilayer ceramic capacitor including a plating layer as the outermost layer according to an embodiment of the present invention. FIG. 1 is a flow diagram showing a method for separating and recovering rare earth elements and metal elements from post-sintering waste (sintering for fired electrode layers) of a multilayer ceramic capacitor having a plating layer 34 as the outermost layer, the method including a plating removal step.

[0015] In this embodiment, a method for separating and recovering rare earth components and metal components (first metal components and second metal components) from post-fired waste after firing for fired electrode layers of multilayer ceramic capacitors is described. The post-fired waste is divided into post-fired waste from multilayer ceramic capacitors that include fired electrode layers as their outermost layers and post-fired waste from multilayer ceramic capacitors that include a plating layer as their outermost layer on the fired electrode layer. In this embodiment, the separation and recovery method for post-fired waste from multilayer ceramic capacitors that include a fired electrode layer as their outermost layer is first described, and then the separation and recovery method for post-fired waste from multilayer ceramic capacitors that include a plating layer as their outermost layer on the fired electrode layer is described. In this embodiment, post-fired waste after firing for fired electrode layers of multilayer ceramic capacitors is sometimes referred to as post-fired waste.

[0016] 1. Post-firing waste of multilayer ceramic capacitors including fired electrode layers as outermost layers 1.1. Separation and recovery method for post-firing waste of multilayer ceramic capacitors including fired electrode layers as outermost layers A method for separating and recovering rare earth components and metal components (first metal component and second metal component) from post-firing waste of multilayer ceramic capacitors including fired electrode layers as outermost layers (firing for fired electrode layers) according to an embodiment of the present invention will be described.

[0017] Fig. 1A is a flow diagram showing a method for separating and recovering rare earth components and metal components from post-sintering waste of multilayer ceramic capacitors (sintering for fired electrode layers) according to an embodiment of the present invention. Fig. 1B is a configuration diagram of an electrolytic refining system. In the separation and recovery method according to an embodiment of the present invention, post-sintering waste of multilayer ceramic capacitors (sintering for fired electrode layers) is used as the starting point for separation and recovery. Here, we will particularly describe post-sintering waste of multilayer ceramic capacitors that include fired electrode layers as the outermost layers.

[0018] (1) Post-fired waste of multilayer ceramic capacitors containing fired electrode layers as outermost layers Before describing the post-fired waste of multilayer ceramic capacitors containing fired electrode layers as outermost layers, the multilayer ceramic capacitors manufactured by the manufacturing process for multilayer ceramic capacitors and the manufacturing process for the multilayer ceramic capacitors will be described below.

[0019] (1-1) Multilayer Ceramic Capacitor Fig. 2 is an external perspective view showing an example of a multilayer ceramic capacitor according to an embodiment of the present invention. Fig. 3 is a cross-sectional view taken along line III-III in Fig. 2 when the multilayer ceramic capacitor includes baked electrode layers as the outermost layers. Here, a two-terminal multilayer ceramic capacitor will be described as an example of the multilayer ceramic capacitor 10.

[0020] As shown in FIGS. 2 and 3 , the multilayer ceramic capacitor 10 includes, for example, a rectangular parallelepiped laminate 12 and external electrodes 30 disposed on both ends of the laminate 12 .

[0021] The laminate 12 has a plurality of stacked ceramic layers 14 and a plurality of internal electrode layers 16 stacked on the ceramic layers 14. Furthermore, the laminate 12 has a first main surface 12a and a second main surface 12b facing each other in a height direction (stacking direction) x, a first side surface 12c and a second side surface 12d facing each other in a width direction y perpendicular to the height direction x, and a first end surface 12e and a second end surface 12f facing each other in a length direction z perpendicular to the height direction x and the width direction y. The ceramic layers 14 and the internal electrode layers 16 are stacked in the height direction x.

[0022] The first internal electrode layer 16 a and the second internal electrode layer 16 b can be made of, for example, a conductive material containing a magnetic base metal, and the magnetic base metal may be a simple metal or an alloy. Examples of magnetic base metals include Ni and Fe. Here, a metal that has a higher ionization tendency than hydrogen is referred to as a base metal.

[0023] The ceramic layer 14 comprises an aggregate of multiple ceramic particles (BTs in FIG. 5 , which will be described later and are also referred to as ceramic sintered bodies). Each ceramic particle can be formed, for example, from a dielectric material. Examples of such dielectric materials include perovskite-type compounds containing BaTiO 3 , CaTiO 3 , SrTiO 3 , or CaZrO 3 as the main component and dielectric ceramics having a perovskite structure. When the dielectric material is the main component, a rare earth element is added to the dielectric material as an additive depending on the desired characteristics of the laminate 12. Examples of the added rare earth element include at least one of Dy, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb, and Lu. The dielectric material may also contain minor components, such as Mn compounds, Fe compounds, Cr compounds, Co compounds, and Ni compounds, in amounts less than the main components. At least one of Si, Mg, Ba, and Mn may also be added to the main components as an additive. However, because these minor components and additives may cause a decrease in the quality of the rare earth components during separation and recovery, these minor components and additives may be omitted.

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

[0025] The external electrode 30 includes a first external electrode 30a and a second external electrode 30b. The first external electrode 30a is connected to the first internal electrode layer 16a and is disposed on at least the surface of the first end face 12e. The second external electrode 30b is connected to the second internal electrode layer 16b and is disposed on at least the surface of the second end face 12f.

[0026] The external electrode 30 includes a baked electrode layer 32. The first external electrode 30a includes a first baked electrode layer 32a. The second external electrode 30b includes a second baked electrode layer 32b. The baked electrode layer 32 is the outermost layer of the multilayer ceramic capacitor 10. In other words, the baked electrode layer 32 is the outermost layer of the layers arranged on the laminate 12.

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

[0028] (1-2) Method for Manufacturing the Multilayer Ceramic Capacitor Next, a method for manufacturing the multilayer ceramic capacitor 10 will be described.

[0029] (Step 1) First, a dielectric sheet for the ceramic layer and a conductive paste for the internal electrode layer are prepared. The dielectric sheet for the ceramic layer is formed from a dielectric slurry containing, for example, but not limited to, BaTiO3 as a main component and Dy as an additive. The conductive paste for the internal electrode layer is formed from, for example, but not limited to, Ni as a main component. The dielectric sheet and the conductive paste for the internal electrode layer contain a binder and a solvent. The binder and solvent are composed of a resin component, and various known thermosetting resins such as epoxy resin, phenoxy resin, phenolic resin, urethane resin, and polyimide resin can be used as the resin component.

[0030] (Step 2) Then, a conductive paste for the internal electrode layers is printed in a predetermined pattern on the dielectric sheet by, for example, screen printing, gravure printing, etc. In this way, a dielectric sheet on which the pattern of the first internal electrode layer is formed, and a dielectric sheet on which the pattern of the second internal electrode layer is formed are prepared.

[0031] Furthermore, with regard to the dielectric sheets, outer layer dielectric sheets on which no internal electrode layer patterns are printed are also prepared.

[0032] A predetermined number of dielectric sheets for outer layers, on which no pattern of internal electrode layers is printed, are stacked. A dielectric sheet on which a pattern of a first internal electrode layer is printed and a dielectric sheet on which a pattern of a second internal electrode layer is printed are sequentially stacked on top of the dielectric sheets to form a portion that will become an internal layer portion. A predetermined number of dielectric sheets for outer layers, on which no pattern of an internal electrode layer is printed, are stacked on top of the portion that will become an internal layer portion. This forms a laminated sheet having an internal layer portion and an external layer portion. The dielectric sheets may also be referred to as unfired ceramic layers, i.e., ceramic layers before firing of the laminated chip. The pattern of the internal electrode layers may also be referred to as unfired internal electrode layers, i.e., internal electrode layers before firing of the laminated chip.

[0033] (Step 3) Next, the laminated sheet is pressed in the lamination direction by means of a hydrostatic press or the like to produce a laminated block.

[0034] (Step 4) The laminated block is then cut to a predetermined size to produce laminated chips. FIG. 4 is a schematic diagram showing the state of the unfired ceramic layers and unfired internal electrode layers in a cross section of the laminated chip parallel to a plane including the longitudinal direction and the lamination direction. FIG. 4 shows a cross section of the laminated chip on which the external electrodes 30 have not yet been formed. The laminated chip in FIG. 4 is in a state prior to degreasing (step 5) and firing (step 6). The resin component contained in the laminated chip is not shown. As shown in FIG. 4, the laminated chip is formed by alternately stacking unfired internal electrode layers 16_U and unfired ceramic layers 14_U.

[0035] The laminated chip as a whole contains a first metal powder (Ni_P in FIG. 4), ceramic powders (BT_P, BT_P in FIG. 4), rare earth powder (Dy_P in FIG. 4), and a resin component. The first metal powder mainly constitutes the internal electrode layer 16_U when unsintered. The ceramic powder mainly constitutes the ceramic layer 14_U when unsintered.

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

[0037] The ceramic powder is an aggregate of dielectric materials. As described above, examples of the dielectric materials include BaTiO3, CaTiO3, SrTiO3, and CaZrO3. The ceramic powder includes a first ceramic powder and a second ceramic powder. The second ceramic powder has a smaller particle size than the first ceramic powder.

[0038] The rare earth powder is an aggregate of rare earth atoms, which are rare earth components. As described above, the rare earth atoms can be at least one of Dy, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb, and Lu.

[0039] The resin components are binders and solvents for producing conductive pastes for the dielectric sheets and internal electrode layers. The binders and solvents contain resin components, and various known thermosetting resins such as epoxy resins, phenoxy resins, phenolic resins, urethane resins, and polyimide resins can be used as the resin components.

[0040] The state of the powder in the laminated chip will be further explained using FIG. 4. The schematic diagram in FIG. 4 shows the state of various powders contained in the laminated chip before degreasing (step 5) and firing (step 6). Note that the resin component is omitted from FIG. 4. As shown in FIG. 4, in this embodiment, the unfired ceramic layer 14_U is primarily composed of a first ceramic powder (BT1_P in FIG. 4). Furthermore, in the unfired ceramic layer 14_U, the first ceramic powder and the rare earth powder (Dy_P in FIG. 4) are at least partially adhered to each other. As shown in the example in FIG. 4, the rare earth powder is primarily adhered to the surface of the first ceramic powder, and is not essentially chemically bonded to the interior of the first ceramic powder. Furthermore, in this embodiment, the unfired internal electrode layer 16_U is primarily composed of a first metal powder (Ni_P in FIG. 4). In the unsintered internal electrode layer 16_U, the first metal powder and the second ceramic powder (BT2_P in FIG. 4) are at least partially adhered to each other. As shown in the example of FIG. 4, the second ceramic powder is primarily adhered to the surface of the first metal powder, and is not essentially chemically bonded to the first metal powder by penetrating into the first metal powder. The term "adhered" may also include partial chemical bonding between powders such as the first metal powder, ceramic powder, and rare earth powder. Note that chemical bonding refers to bonding between multiple atoms, such as ionic bonds, covalent bonds, and metallic bonds, in which positive and negative charges attract and bind each other.

[0041] (Step 5) Next, the resin components in the stacked chips are removed. Hereinafter, the removal of the resin components in step 5 is a degreasing step in the manufacturing process. The degreasing temperature in step 5 is, for example, higher than 800°C and lower than 1000°C.

[0042] (Step 6) Next, the laminated chip is fired to produce the laminate 12. The firing temperature for the laminated chip depends on the materials of the ceramic layers and internal electrode layers, which are dielectrics, but is preferably, for example, higher than 1000°C and lower than 1400°C. Steps 1 to 6 constitute the laminate formation process. The firing in step 6 may also be referred to as firing the laminated chip. This firing turns the unfired laminated chip into the laminate 12. Furthermore, the unfired internal electrode layers 16_U and the unfired ceramic layers 14_U are fired to become the internal electrode layers 16 and the ceramic layers 14.

[0043] (Step 7) Next, a baked electrode layer paste containing a plurality of second metal powders (e.g., Cu powder) is applied to the first and second end faces 12e, 12f of the laminate 12 and fired to form baked electrode layers 32, which are external electrodes 30. The second metal powder is, for example, an aggregate of second metal atoms, which is the second metal component. Each second metal powder in the baked electrode layer paste is dispersed singly or in contact with other powders, including other second metal powders. In other words, each second metal powder in the baked electrode layer paste is not chemically bonded to other second metal powders or powders of other additives. The baked electrode layer paste is then fired, resulting in a sintered state of the second metal powders. The firing temperature of the baked electrode layer paste is preferably 700°C or higher and 900°C or lower. The firing in step 7 is sometimes referred to as firing for the baked electrode layer.

[0044] Next, the state of each layer of the multilayer ceramic capacitor 10 after firing for the fired electrode layers in (Step 7) will be described. Fig. 5 is an enlarged view of the a portion in Fig. 3, and is a schematic diagram showing the state of each layer after firing for the fired electrode layers. Fig. 6 is a partial enlarged view of the ceramic layer in Fig. 5. After firing for the fired electrode layers, the multilayer ceramic capacitor 10 is in a sintered state with each portion, such as the ceramic layers 14, internal electrode layers 16, and external electrodes 30.

[0045] In the ceramic layer 14, the ceramic powder (BT_P, BT_P in FIG. 4 ) undergoes firing to become ceramic particles BT (BT in FIG. 5 ) in a sintered state, as shown in FIG. 5 . The ceramic powder (BT_P, BT_P in FIG. 4 ) undergoes firing of the laminated chip, for example, in step 6, to form sintered ceramic particles BT. The sintered ceramic particles BT are sometimes referred to as ceramic sintered bodies BT. For example, firing of ceramic powders evolves the contact between the ceramic powder particles from point contact to surface contact. This promotes chemical bonding between the ceramic powder particles, forming integrated ceramic particles BT (ceramic sintered bodies BT). The ceramic particles BT may be formed by partial chemical bonding of the ceramic powder with the rare earth powder. In the example of FIG. 5 , the ceramic layer 14 includes an aggregate of multiple ceramic particles BT. Note that most of the first ceramic powder (BT1_P in FIG. 4) forms the ceramic layer 14, for example, by undergoing firing of the laminated chip in (Step 6). Also, most of the second ceramic powder (BT2_P in FIG. 4) adhering to the first metal powder (Ni_P in FIG. 4) forms the ceramic layer 14, for example, by undergoing firing of the laminated chip in (Step 6). At this time, most of the second ceramic powder (BT2_P in FIG. 4) is not basically bonded to the fired internal electrode layer 16, but is pushed out from the fired internal electrode layer 16, and is fired together with the first ceramic powder to form the ceramic layer 14.

[0046] Further describing the ceramic layer 14, each ceramic particle BT is formed of a core-shell 40 as shown in FIG. 6 . The core-shell 40 includes a core portion 42 including 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 primarily formed of a ceramic material. The shell portion 44 is formed by incorporating, for example, a rare earth component as an additive into the ceramic material. The shell portion 44 may also incorporate other minor components such as Mn compounds. Grain boundaries 50 exist at the boundaries between the ceramic particles BT. The grain boundaries 50 contain rare earth inclusions. The rare earth inclusions contain the rare earth component, for example, in the form of an oxide. An example of the oxide of the rare earth component is dysprosium oxide (DyO). The rare earth inclusions may also contain, for example, silicon dioxide (SiO), manganese dioxide (MnO), etc. Note that the above description has been given regarding the core-shell structure of each ceramic particle BT. However, each ceramic particle BT may have a structure in which the rare earth element or the like is incorporated up to the center of the ceramic particle BT. Furthermore, ceramic particles BT having such a structure and ceramic particles BT having a core-shell structure may be mixed in the ceramic layer 14.

[0047] The internal electrode layer 16 is formed by firing the first metal powder (Ni_P in FIG. 4 ) to form first metal particles (Ni in FIG. 5 ) in a sintered state as shown in FIG. 5 . The first metal powder (Ni_P in FIG. 4 ) is fired, for example, to form the sintered internal electrode layer 16 by firing the laminated chip (step 6). In FIG. 5 , Ni powder, which is the first metal powder, is sintered to form Ni particles (first metal particles). The sintered first metal particles are sometimes referred to as a first metal sintered body. For example, when the first metal powder is heated by firing, the contact between the first metal powder particles develops from point contact to surface contact. This progresses the bonding between the first metal powder particles, forming integrated first metal particles (first metal sintered body). In the example of FIG. 5 , the internal electrode layer 16 includes an aggregate of multiple first metal particles.

[0048] In the baked electrode layer 32 (external electrode 30), a second metal powder (e.g., Cu powder) undergoes firing for the baked electrode layer, becoming second metal particles (Cu in FIG. 5) in a sintered state as shown in FIG. 5 . In FIG. 5 , the Cu powder, which is the second metal powder, is sintered to become Cu particles (second metal particles). The second metal particles in a sintered state are sometimes referred to as second metal sintered bodies. For example, when the second metal powder is heated during firing for the baked electrode layer, contact between the second metal powder particles develops from point contact to surface contact. This progresses bonding between the second metal powder particles, forming integrated second metal particles (second metal sintered bodies). In the example of FIG. 5 , the baked electrode layer 32 includes an aggregate of multiple second metal particles.

[0049] The multilayer ceramic capacitor 10 is manufactured by the above-described manufacturing process.

[0050] Here, in the present embodiment, the post-firing waste refers to waste generated after the firing of the fired electrode layers in (step 7) when the multilayer ceramic capacitor 10 is manufactured by the above-described manufacturing method for the multilayer ceramic capacitor 10.

[0051] (2) Flow of Separation and Recovery Method: Referring to Figure 1A, the flow of the separation and recovery method for post-fired waste of multilayer ceramic capacitors including a fired electrode layer as the outermost layer of this invention will be described. The separation and recovery method of Figure 1A includes a common separation and recovery route, a rare earth component separation and recovery route, a first metal component separation and recovery route, and a second metal component separation and recovery route. The rare earth component separation and recovery route and the first metal component separation and recovery route branch off from the common separation and recovery route. The second metal component separation and recovery route branches off from the rare earth component separation and recovery route.

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

[0053] (Step (A): Preparation of Firing Waste) In step (A), post-firing waste (firing for fired electrode layers) of a multilayer ceramic capacitor is prepared. The post-firing waste is as described above. The post-firing waste includes a laminate 12 including ceramic layers 14 and internal electrode layers 16, and fired electrode layers 32. The ceramic layers 14, internal electrode layers 16, and fired electrode layers 32 are in a sintered state.

[0054] (Step (B): Refining) In step (B), the fired waste is refined. For example, but not limited to, the fired waste is pulverized by pulverization. The pulverization can be performed by, but not limited to, a method of applying a pulverizing force by vibration to the object using a vibrating mill or the like, a method of grinding the object, a method of applying a pulverizing force by impact to the object, or the like. It is preferable to refine the fired waste to an extent that it can be easily separated in the magnetic separation in step (C) described below. By refining the fired waste, it is possible to obtain a ceramic refined product obtained by refining the sintered ceramic layer 14, a sintered rare earth-containing material, a first metal refined product obtained by refining the sintered internal electrode layer 16, and a second metal refined product obtained by refining the sintered baked electrode layer 32. The ceramic refined product includes, for example, a ceramic material such as BaTiO3, CaTiO3, SrTiO3, or CaZrO3. The rare earth-containing material may include, for example, dysprosium oxide (DyO), and may also include, for example, silicon dioxide (SiO), manganese dioxide (MnO). The first finely divided metal material may include, for example, a first metal component such as Ni and Fe. The second finely divided metal material may include, for example, a second metal component such as Cu. The average particle size of the post-calcination waste after being reduced in size is not limited. The average particle size can be determined, for example, using a sieve.

[0055] (Step (C): Magnetic Separation) In the magnetic separation of step (C), the post-sintered waste after being pulverized in step (B) is magnetically separated using a magnet. That is, by magnetic separation, the post-sintered waste is separated into a first separated product and a second separated product and recovered.

[0056] The first separated material includes a first metal fine particle (Ni in FIG. 1A ) and a ceramic fine particle (BT in FIG. 1A ). The first metal fine particle includes a first metal component, which is a magnetic base metal. On the other hand, the ceramic fine particle is not magnetic. The first separated material is separated as a magnetic substance by magnetic separation. Specifically, in the first separated material, when the magnetic first metal fine particle is separated as a magnetic substance, the non-magnetic ceramic fine particle is caught in the first metal fine particle.

[0057] The second separated material includes a second metal fine particle (Cu in FIG. 1A), a rare earth-containing material (Dy2O3 in FIG. 1A), and a ceramic fine particle (BT in FIG. 1A). The second metal fine particle contains a second metal component, which is a non-magnetic precious metal. The rare earth-containing material and the ceramic fine particle are non-magnetic. Therefore, the second metal fine particle, the rare earth-containing material, and the ceramic fine particle are separated as non-magnetic materials by magnetic separation.

[0058] Therefore, by this magnetic separation, the second separated material is removed from the post-sintering waste, and the first separated material containing the first metal fine particles can be separated and recovered as the first metal component. For example, the first metal fine particles are finely divided Ni (the first metal component) that constitutes the internal electrode layer 16 in a sintered state. In the present invention, the separation and recovery of the first metal component includes not only the separation and recovery of the first metal component itself, but also the separation and recovery of the first separated material containing the first metal fine particles as the first metal component.

[0059] The first metal component includes the first metal atom itself, a first metal component compound which is a reaction product of the first metal atom chemically reacting with other atoms, a solution of the first metal atom, a solution of the first metal component compound, etc. The state of the first metal component may be any of a liquid state, a solid state, or a mixed state of liquid and solid. The first metal component may be any of an amorphous state, a crystalline state, or a mixed state of amorphous and crystalline.

[0060] In other words, by this magnetic separation, the second fine metal material and the rare earth-containing material can be separated and recovered from the post-burning waste, with the first separated material removed.

[0061] In addition, during magnetic separation, it is preferable to mix and disperse the post-calcination waste after being pulverized in step (B) with an aqueous solvent such as water to create a mixed state, and then separate it using a magnet.

[0062] When the pulverized calcined waste is mixed with an aqueous solvent to form a mixed state, i.e., a slurry state, the ceramic pulverized material, rare earth-containing material, first metal pulverized material, and second metal pulverized material contained in the pulverized calcined waste can be dispersed. Therefore, in step (C), the first separated material and the second separated material can be easily separated using a magnet. When the pulverized calcined waste is in a dry state, the first separated material and the second separated material tend to be less dispersed than when in a slurry state. Therefore, for example, when the first separated material is attracted to a magnet, the second separated material may become entangled in the first separated material and be attracted to the magnet, making it difficult to separate the first separated material and the second separated material.

[0063] (Step (D): Dissolution of Second Separation Product) In step (D), the second separation product separated and recovered in step (C) is dissolved in a mineral acid with no oxidizing power. This allows for the production of a rare earth component-containing solution in which the rare earth components of the rare earth-containing material contained in the second separation product are dissolved. Therefore, the rare earth component-containing solution can be separated and recovered as a rare earth component. At this time, the ceramic fine particles and the second metal fine particles in the second separation product are precipitated. The ceramic fine particles react with the mineral acid with no oxidizing power and precipitate as undissolved matter. Furthermore, the second metal fine particles, such as Cu, do not dissolve in the mineral acid with no oxidizing power because they have a lower ionization tendency than the hydrogen ions contained in the mineral acid with no oxidizing power. The mineral acid with no oxidizing power is, for example, at least one selected from the group including dilute sulfuric acid and hydrochloric acid.

[0064] As described above, the rare earth component is separated and recovered as a rare earth component-containing solution. In the present invention, the separation and recovery of the rare earth component includes not only the separation and recovery of the rare earth component itself, but also the separation and recovery of the rare earth component-containing solution as the rare earth component. In other words, the rare earth component includes rare earth atoms themselves, rare earth component compounds which are reaction products of rare earth atoms chemically reacting with other atoms, solutions of rare earth atoms, solutions of rare earth component compounds, etc. Furthermore, the rare earth component may be in any of a liquid state, a solid state, or a mixed state of liquid and solid. Furthermore, the rare earth component may be in any of an amorphous state, a crystalline state, or a mixed state of amorphous and crystalline.

[0065] In step (D), it is preferable to adjust the pH of the rare earth component-containing solution to 1.5 or more and 2.5 or less by adding a mineral acid having no oxidizing power.

[0066] In step (D), the rare earth component-containing solution is adjusted to a pH of 1.5 or higher and 2.5 or lower using a non-oxidizing mineral acid, thereby dissolving mainly the rare earth components in the rare earth-containing material in the non-oxidizing mineral acid. Furthermore, adjusting the pH to a stronger acid than the above range may result in the ceramic fine particles being dissolved in the non-oxidizing mineral acid, so it is preferable to adjust the pH to within the above range. More preferably, the rare earth component-containing solution is adjusted to a pH of 2 by adding a non-oxidizing mineral acid.

[0067] When the post-calcination waste in a slurry state is subjected to magnetic separation in step (C), the separated second separated material is in a slurry state with a pH of about 7. By adding a mineral acid with no oxidizing power to this slurry, it is also possible to produce a rare earth component-containing solution with an adjusted pH of 1.5 or more and 2.5 or less. However, the second separated material after magnetic separation does not need to be in a slurry state and may be in a dry state.

[0068] When the ceramic fine particles contained in the second separated material are, for example, BaTiO3, dilute sulfuric acid is preferably used as the non-oxidizing mineral acid. When dilute sulfuric acid is used, insoluble BaSO4 is formed on the surface of the BaTiO3 ceramic fine particles, allowing the ceramic fine particles to precipitate. Note that second metal fine particles, such as Cu, have a lower ionization tendency than the hydrogen ions contained in the non-oxidizing mineral acid and therefore do not dissolve in the non-oxidizing mineral acid. On the other hand, rare earth powder can be dissolved in dilute sulfuric acid. Specifically, for example, when a second separated material mainly containing Cu second metal fine particles, a rare earth-containing material such as DyO3, and a BaTiO3 ceramic fine particle is dissolved in dilute sulfuric acid, BaTiO3 precipitates and Cu does not dissolve. Meanwhile, a dysprosium sulfate (Dy(SO)3) solution, in which Dy from the rare earth-containing material is dissolved in dilute sulfuric acid, is produced as a rare earth component-containing solution.

[0069] As mentioned above, hydrochloric acid or the like can be used as the non-oxidizing mineral acid in addition to dilute sulfuric acid. However, if hydrochloric acid is used as the non-oxidizing mineral acid, soluble BaCl is formed on the surface of the finely divided ceramic material, BaTiO. Therefore, it is preferable to precisely adjust the pH of the hydrochloric acid or the like so as to precipitate the finely divided ceramic material and dissolve the rare earth-containing material while leaving the finely divided second metal material undissolved.

[0070] (Step (F): Filtration) In step (F), the rare earth component-containing solution containing the precipitated ceramic fine particle and the undissolved second metal fine particle produced in step (D) is filtered to separate the undissolved ceramic fine particle and the second metal fine particle from the rare earth component-containing solution. By this solid-liquid separation, the rare earth component-containing solution from which the undissolved ceramic fine particle and the second metal fine particle have been removed can be separated and recovered as rare earth components from the rare earth component-containing solution containing the undissolved ceramic fine particle and the second metal fine particle.

[0071] For example, in step (D), BaTiO is precipitated, and the finely divided second metal particles such as Cu are not dissolved, and a dysprosium sulfate (Dy(SO)) solution containing Dy dissolved in dilute sulfuric acid is produced as a rare earth component-containing solution. In this case, the dysprosium sulfate solution from which BaTiO and Cu have been removed can be separated and recovered as rare earth components by filtration in step (F).

[0072] The filtration can be carried out using filter paper (filter cloth). The mesh size of the filter paper (filter cloth) is preferably such that the undissolved ceramic fine product and the second metal fine product do not pass through the filter paper (filter cloth).

[0073] The rare earth component-containing solution containing the undissolved ceramic fine product and the second metal fine product produced in step (D) can be solid-liquid separated, and the solid-liquid separation is not limited to filtration, and can be performed by any known method appropriately selected from decantation, centrifugation, etc. Filtration is more preferred.

[0074] (Step (G): Neutralization) In step (G), the rare earth component-containing solution obtained in step (F) is neutralized to precipitate and recover the rare earth component. The precipitated rare earth component is separated and recovered, for example, by filtering the neutralized rare earth component-containing solution. At this time, the rare earth component is separated and recovered as a rare earth component compound (e.g., Dy(OH)3, etc.) by neutralization. In the present invention, separation and recovery of the rare earth component includes not only the separation and recovery of the rare earth component itself, but also the separation and recovery of a rare earth component compound, which is a reaction product of a chemical reaction of the rare earth component, as the rare earth component.

[0075] An alkali is used for neutralization. Examples of alkalis include sodium hydroxide and potassium hydroxide. Although the pH range in which rare earth components precipitate can change when the redox potential changes, using these alkalis can stabilize the pH range in which rare earth components precipitate.

[0076] In the neutralization step (G), the rare earth component is recovered by adjusting the pH of the rare earth component-containing solution to a value between 6 and 9. This allows the precipitate resulting from the neutralization reaction to be efficiently separated and recovered as the rare earth component. More preferably, the rare earth component-containing solution is adjusted to a pH of 8 by adding an alkali.

[0077] For example, when a dysprosium sulfate solution from which BaTiO3, Cu, and the like have been removed is obtained in the filtration of step (F), dysprosium hydroxide (Dy(OH)3) is obtained as a rare earth component compound by neutralization with sodium hydroxide. That is, since the dysprosium sulfate solution is acidic, neutralization with an alkali allows the rare earth component dysprosium to precipitate as dysprosium hydroxide (Dy(OH)3), which can be separated and recovered. Here, dysprosium hydroxide (Dy(OH)3) can be separated and recovered by filtering the dysprosium sulfate solution neutralized with an alkali. In addition to filtration, known methods such as decantation and centrifugation can also be used.

[0078] Note that some metal components (so-called contaminants) are not separated as the first separated product in the magnetic separation in step (C) but are entrained in the second separated product. Therefore, the rare earth component-containing solution produced by dissolving the second separated product in step (D) may contain contaminating metal components. These metal components include, for example, Ti, Mn, and Ni. Then, in step (G), Ti, Mn, and the like can be separated and recovered by adding an alkali to the rare earth component-containing solution to adjust the pH to, for example, between 3 and 5, preferably about 4. In this case, Ti precipitates as, for example, Ti(OH)4, and Mn precipitates as, for example, Mn(OH)2. Therefore, Ti(OH)4, Mn(OH)2, and the like are recovered by filtering the rare earth component-containing solution adjusted to about pH 4.

[0079] Thereafter, an alkali is further added to the solution containing the rare earth elements from which Ti, Mn, etc. have been separated, and the pH is adjusted to between 6 and 9, preferably about 8, as described above, to separate and recover the rare earth elements.

[0080] Thereafter, Ni and other components can be separated and recovered by adding an alkali to the solution from which Ti, Mn, rare earth components, etc. have been separated, and adjusting the pH to, for example, more than pH 9 but not more than pH 11, preferably about pH 10. In this case, Ni precipitates as, for example, Ni(OH)2. The solution adjusted to about pH 10 is filtered to recover Ni(OH)2 and other components.

[0081] By repeating stepwise neutralization and filtration in this manner, various components (contaminants, rare earth components, etc.) contained in the rare earth component-containing solution can be separated and recovered.

[0082] Furthermore, in the stepwise neutralization of the rare earth component-containing solution as described above, the rare earth component-containing solution is neutralized to a pH of 3 or more and 5 or less, preferably about pH 4, before separating the rare earth component. This allows contaminants such as Ti and Mn to be first removed from the rare earth component-containing solution. Since contaminants such as Ti and Mn have been removed from the rare earth component-containing solution in this manner, it is possible to further facilitate separation of the rare earth component using the rare earth component-containing solution in a state in which these contaminants have been removed.

[0083] (Step (E): Dissolution of Undissolved Material) In step (E), the finely divided ceramic material and the finely divided second metal material removed by filtration in step (F) are dissolved in ammonia water. This produces a second metal solution in which the second metal component contained in the finely divided second metal material is dissolved. Therefore, the second metal component can be separated and recovered from the second metal solution. At this time, the finely divided ceramic material is precipitated.

[0084] Specifically, a second metal fine particle containing a second metal component such as Cu and a ceramic fine particle of BaTiO are dissolved in ammonia water. 2+ A second metal solution containing ammine copper complexes such as BaTiO3 precipitates in the second metal solution.

[0085] As described above, the second metal component is separated and recovered as a second metal solution. In the present invention, separation and recovery of the second metal component includes not only the separation and recovery of the second metal component itself, but also the separation and recovery of the second metal component solution as the second metal component. Here, the second metal component includes the second metal component itself, a second metal component compound which is a reaction product of the second metal component chemically reacting 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 may be any of a liquid state, a solid state, or a mixed state of liquid and solid. Furthermore, the second metal component may be any of an amorphous state, a crystalline state, or a mixed state of amorphous and crystalline.

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

[0087] Furthermore, when the undissolved ceramic fine particles and the second metal fine particles extracted in step (F) are dissolved in ammonia water, it is preferable to add an ammonium salt, such as ammonium sulfate, to the ammonia water. Here, the ammonia water serves as a source of ammonia for forming an ammine complex, such as a copper ammine complex, with the second metal component, such as Cu. The ammonium salt also provides a counterion to the ammine complex, such as a copper ammine complex. For example, an ammonium salt, such as ammonium sulfate, can be used to dissolve [Cu(NH3)4] 2+ The copper ammine complex is treated with SO4 as a counter ion. 2- Even if the concentration of ammonia decreases, salts such as CuSO4 are formed, suppressing the deposition of Cu ions.

[0088] (Step (J): Filtration) In step (J), the second metal solution containing the precipitated ceramic microparticles produced in step (E) is filtered to separate the precipitated ceramic microparticles from the second metal solution. By this solid-liquid separation, the second metal solution from which the precipitated ceramic microparticles have been removed can be separated and recovered as a second metal component from the second metal solution containing the precipitated ceramic microparticles.

[0089] For example, in step (E), in a state where BaTiO3 is precipitated, a second metal solution is generated in which a second metal component such as Cu is dissolved in ammonia water. The second metal solution may be, for example, [Cu(NH3)4] 2+ In this case, the second metal solution containing the copper ammine complex from which BaTiO3 has been removed by filtration in step (J) can be separated and recovered as the second metal component.

[0090] Filtration can be carried out using filter paper (filter cloth). 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). In addition, the solid-liquid separation of the second metal solution containing the precipitated ceramic microparticles produced in step (E) is not limited to filtration, and solid-liquid separation can be carried out by a method appropriately selected from known methods such as decantation and centrifugation. Filtration is more preferred.

[0091] (Step (H): Electrolytic Refining) In step (H), the first separated material separated and recovered in step (C) is introduced into an electrolytic solution 61a (FIG. 1B) and electrolytically refined to recover a first metal component from the first separated material. The first separated material includes a first metal fine particle containing the first metal component and a ceramic fine particle containing a ceramic material. For example, electrolytic refining is performed using an electrolytic refining system 60 shown in FIG. 1B. FIG. 1B is a configuration diagram of the electrolytic refining system. The electrolytic refining system 60 includes an electrolytic cell 61, an anode 62, a cathode 63, a power source 64, and an anode basket 65. The electrolytic cell 61 is filled with an electrolytic solution 61a, and the anode 62 and cathode 63 are attached to the electrolytic cell 61 so as to be immersed in the electrolytic solution 61a. The anode basket 65 is capable of containing the first separated material, which is the object to be treated 65a, and is formed integrally with the anode 62. The anode basket 65 is immersed in the electrolyte 61 a and is configured to be permeable to ions of the first metal component of the first metal fine particles in the first separation material. A power source 64 applies electricity between the anode 62 and the cathode 63.

[0092] By applying a predetermined voltage to the power supply 64, the first metal component of the first metal fine particle in the first separated material contained in the anode basket 65 is ionized. The first metal component ionized at the anode 62 reaches the cathode 63. Ions of the first metal component are precipitated on the surface of the cathode 63. This allows the first metal component of the first metal fine particle to be separated and recovered from the first separated material by electrolytic refining. Note that mainly the ceramic fine particle other than the first metal component precipitates in the first separated material.

[0093] For example, if the first metal component of the first metal fine particle is Ni (Ni in FIG. 1B), the anode 62 will have Ni+2e - →Ni 2+ On the other hand, at the cathode 63, the reaction 2+ +2e - → A reaction of Ni occurs, and Ni is precipitated on the surface of the cathode 63, allowing it to be separated and recovered. Note that the components other than the first metal component in the first separated product, mainly the fine ceramic product (BT2 in FIG. 7B), are precipitated.

[0094] When recovering the first metal component from the first separated product by such electrolytic refining, almost no hydrogen is generated when the first metal component of the first metal fine particle is ionized. Therefore, electrolytic refining can suppress explosions caused by hydrogen combining with oxygen, allowing for safe separation and recovery. Furthermore, electrolytic refining can deposit the first metal component to be recovered on an electrode, allowing for recovery of a relatively high-purity first metal component.

[0095] Note that, as long as electrolytic refining is possible by passing a current through the metal powder-containing material, which is the treatment target 65a, the viewpoint of the innovation may be the electrolytic refining system 60 or the first separated material, which is the treatment target 65a. When the electrolytic refining system 60 is improved, it is possible to combine magnets with electrodes so that the metal powder adheres to the electrodes during current flow. In this case, it is not necessary to process the metal powder-containing material, which is the treatment target 65a, into a mass as described below.

[0096] In this embodiment, the first separated material, which is the processing target 65a, includes a first fine metal particle and a ceramic fine particle. If the first fine metal particle is dispersed in the first separated material, even when a voltage is applied from the anode 62, current does not flow easily throughout the first fine metal particle in the anode basket 65, making it difficult to ionize the entire first fine metal particle. As described above, by processing the first separated material into a mass in which the metal powder particles are in contact with each other to the extent that current can flow, the degree of contact between the first fine metal particles in the first separated material can be increased. Therefore, current can be easily passed throughout the first fine metal particle in the anode basket 65, making it easier to ionize the entire first fine metal particle. Forming a mass so that the proportion of the first fine metal particle in the first separated material is 60 wt % or more, more preferably 80 wt % or more, and even more preferably 90 wt % or more makes it easier to pass current through the first fine metal particle, which is preferable.

[0097] One possible approach to devising the first separated material, which is the processing target 65a, is to process it into a lump in which the metal powder is in contact with the material to the extent that an electric current can flow. Examples of methods for processing the first separated material into a lump include compressing the first separated material to form a tightly adhered mass, heat-treating the first separated material by partially melting the metal powder with heat to form a tightly adhered mass, and combinations of these. The temperature for the heat treatment is, for example, 600°C or higher, preferably 800°C or higher, and more preferably 1200°C or higher. It is preferable to compress the first separated material to a degree that causes plastic deformation of the metal powder. In other words, it is preferable to compress the first separated material to a temperature equal to or higher than the yield stress of the metal powder. A binder may also be added to the first separated material when processing it into a lump. The binder is not limited as long as it can form the first separated material into a lump, and examples thereof include PVA. Using a binder with good thermal decomposition properties is preferable from an environmental perspective, as it is less likely to be burned during heat treatment and leached into wastewater.

[0098] In the above example, the first separated material contained in the anode basket 65 is subjected to electrolytic refining to deposit the metal component on the surface of the cathode 63. However, depending on the type of the first metal component, the first separated material contained in a cathode basket (not shown) may be subjected to electrolytic refining to deposit the first metal component on the surface of the anode 62.

[0099] (Step (I): Various Treatments) In step (I), the first metal component recovered in step (H) can be treated to separate and recover the first metal component as a desired first metal component compound. For example, the first metal component recovered in step (H) is reacted with a solution to produce a first metal solution, thereby separating and recovering the first metal component as a desired first metal component compound. For example, if the first metal component is Ni, the first metal component can be separated and recovered as a first metal component compound such as NiSO4 or NiCl2 by reacting it with sulfuric acid, hydrochloric acid, or the like. In the present invention, separation and recovery of the first metal component includes not only separating and recovering the first metal component itself, but also separating and recovering a first metal component compound, which is a reaction product of the first metal component chemically reacted, as the first metal component.

[0100] (3) Effects According to the above separation and recovery method, it is possible to separate and recover the first metal component constituting the internal electrode layer 16, the second metal component constituting the external electrode 30, and the rare earth component contained in the ceramic layer 14 from post-sintering waste of multilayer ceramic capacitors. This will be explained in detail below.

[0101] The present inventors have considered the effective utilization of various components contained in waste after firing of multilayer ceramic capacitors (firing of fired electrode layers). In the post-firing waste, various components are in a sintered state due to the firing process. For example, the internal electrode layers are formed containing first metal particles (first metal sintered compacts) formed by firing a first metal powder such as Ni. Furthermore, for example, the ceramic layers are formed containing ceramic particles (ceramic sintered compacts) formed by firing a ceramic powder such as BaTiO. Furthermore, for example, the external electrodes are formed containing second metal particles (second metal sintered compacts) formed by firing a second metal powder such as Cu. The inventors have discovered that even when each part of a multilayer ceramic capacitor is in a sintered state, various components contained in the multilayer ceramic capacitor can be separated and recovered by devising a separation and recovery method.

[0102] Furthermore, by pulverizing the fired waste in step (B), it is possible to obtain a ceramic finely divided product, a rare earth-containing material, a first metal finely divided product, and a second metal finely divided product. Then, in step (C), the pulverized fired waste can be separated into a first separated product and a second separated product by separating the first separated product using a magnet. The first separated product includes the ceramic finely divided product and the first metal finely divided product. The second separated product includes the ceramic finely divided product, the rare earth-containing material, and the second metal finely divided product. Therefore, by separating and recovering the first separated product in step (C), it is possible to remove the second separated product from the fired waste, and to separate and recover the first separated product containing the first metal finely divided product as the first metal component.

[0103] Then, in step (D), the second separated material is dissolved in a non-oxidizing mineral acid to produce a rare earth component-containing solution in which the rare earth components in the rare earth powder-containing material are dissolved. This allows the rare earth component-containing solution to be separated and recovered as a rare earth component. At this time, the finely divided ceramic material and the finely divided second metal material are precipitated. The finely divided ceramic material reacts with the non-oxidizing mineral acid to become an undissolved material and precipitate. Furthermore, the finely divided second metal material, such as Cu, does not dissolve in the non-oxidizing mineral acid because it has a lower ionization tendency than the hydrogen ions contained in the non-oxidizing mineral acid.

[0104] Thereafter, the finely divided ceramic particles and the finely divided second metal particles in the second separated product extracted in step (D) are dissolved in ammonia water to produce a second metal solution in which the second metal components, such as Cu, in the finely divided second metal particles are dissolved. This allows the second metal solution to be separated and recovered as the second metal components. At this time, the finely divided ceramic particles in the second separated product do not dissolve in the ammonia water but remain precipitated.

[0105] By carrying out the separation and recovery method including steps (C), (D), and (E), rare earth components can be separated and recovered as a rare earth component-containing solution from the post-calcination waste after pulverization, and the second metal solution can be separated and recovered as a second metal component. Furthermore, as each step is carried out, the proportion of the rare earth component in the material containing the rare earth component and the proportion of the second metal component in the material containing the second metal component increase. Therefore, rare earth components such as Dy and second metal components such as Cu can be recovered at high quality.

[0106] The separation and recovery method of FIG. 1A further includes a step (H). In this step (H), the first separated material is subjected to electrolytic refining, thereby separating and recovering the first metal component from the first separated material. Furthermore, by using electrolytic refining, almost no hydrogen is generated when the first metal component of the first metal fine particle is ionized, allowing the first metal component to be safely recovered. Furthermore, by using electrolytic refining, the first metal component can be recovered with a relatively high purity. In step (H), the ceramic fine particle contained in the first separated material precipitates in the electrolytic solution 61a, and therefore the ceramic fine particle contained in the first separated material and the first metal component are separated.

[0107] Therefore, by carrying out the separation and recovery method including steps (C) and (H), the first metal component can be separated and recovered from the post-sintered waste after pulverization. Furthermore, the proportion of the first metal component in the material containing the first metal component increases as each step is carried out. Therefore, the first metal component, such as Ni, can be recovered at a high quality.

[0108] As described above, the first metal component, the second metal component, the rare earth component, and the like are separated and recovered using post-sintering waste from multilayer ceramic capacitors. Therefore, the post-sintering waste can be used as a resource rather than being discarded as waste, thereby reducing the environmental load.

[0109] 1.2 Experimental Example Hereinafter, an experimental example will be described in which metal components and rare earth components were recovered from post-burning waste.

[0110] [Example] 10 g of fired waste was prepared. The 10 g of fired waste contained 35% by mass (3.5 g) of Ni, a first metal component, 7% by mass (0.7 g) of Cu, a second metal component, 54% by mass (5.4 g) of ceramic particles (ceramic sintered body) of BaTiO3, 2% by mass (0.2 g) of Dy, a rare earth component, and 2% by mass (0.2 g) of contaminants such as Mg, Mn, and SiO2 (step (A)). This fired waste was pulverized and refined (step (B)). The pulverized fired waste was mixed with 100 ml of water to prepare a slurry. This slurry was subjected to magnetic separation using a magnet. 4.5 g of a first separated product and 4.6 g of a second separated product were separated and recovered by this magnetic separation (step (C)). Then, 100 ml of water was added to 4.6 g of the second separated material, and 1 mol% sulfuric acid was added little by little to adjust the pH to 2. This precipitated the ceramic fine particles (BaTiO3) and the second metal fine particles (Cu) in the second separated material, and the Dy contained in the rare earth-containing material was dissolved in the sulfuric acid solution (step (D)). The solution in which the ceramic fine particles (BaTiO3) and the second metal fine particles (Cu) precipitated and the Dy dissolved in the sulfuric acid solution was filtered to obtain 90 ml of dysprosium sulfate (Dy2(SO4)3) solution (step (F)). 1 mol% caustic soda solution was added little by little to the 90 ml of dysprosium sulfate solution as an alkali, and the pH was adjusted to 8 (step (G)). This solution was filtered, and 0.1 g of Dy(OH)3 was separated and recovered. Therefore, by going through this process, approximately 40% of the Dy contained in the post-calcination waste was recovered.

[0111] In addition, 100 ml of water and 2 g of ammonium sulfate were added to 4.1 g of the filtered product of the ceramic fine powder (BaTiO3) and the second metal fine powder (Cu) recovered in step (F), and 1 mol% ammonia water was gradually added to adjust the pH to 9.5. This caused the ceramic fine powder (BaTiO3) to precipitate, and the second metal fine powder (Cu) was dissolved in ammonia water (step (E)). This solution was filtered, and 90 ml of [Cu(NH3)4] 2+Thus, by going through this process, approximately 60% of the Cu contained in the waste after calcination was recovered.

[0112] In addition, 4.5 g of the metal powder-containing material recovered in step (C), mainly consisting of Ni with BaTiO3 attached thereto, was heat-treated to obtain a metal lump. This metal lump was placed in an anode basket 65, a cathode was installed as the counter electrode, and a current was applied necessary to deposit 1.0 g of nickel metal on the cathode, thereby performing electrolytic refining (step (H)). The nickel metal deposited on the anode was peeled off, and 0.9 g of metallic nickel was separated and recovered. 0.9 g of the metallic nickel solution was dissolved in 9 ml of sulfuric acid to obtain a nickel sulfate solution (step (I)).

[0113] [Experimental Results] From the above experiments, it has been found that the separation and recovery method of FIG. 1A uses post-sintering waste of multilayer ceramic capacitors as a starting material, and by going through processes such as magnetic separation and electrolytic refining, it is possible to easily separate and refine high-quality rare earth components such as Dy, Ni, and Cu, a first metal component, and a second metal component.

[0114] 2. Post-fired waste from multilayer ceramic capacitors including a plated layer as the outermost layer on a fired electrode layer 2.1. Separation and recovery method for post-fired waste from multilayer ceramic capacitors including a plated layer as the outermost layer on a fired electrode layer In the multilayer ceramic capacitor 10 including a fired electrode layer as the outermost layer, the external electrode 30 includes a fired electrode layer 32. The fired electrode layer 32 is the outermost layer of the multilayer ceramic capacitor 10 ( FIG. 3 ). However, the form of the external electrode 30 is not limited to this. The external electrode 30 may include a fired electrode layer 32 and a plated layer. The plated layer is the outermost layer of the multilayer ceramic capacitor. A separation and recovery method for post-fired waste from multilayer ceramic capacitors including a plated layer as the outermost layer on a fired electrode layer is described below. Details similar to those in the separation and recovery method for post-fired waste from multilayer ceramic capacitors including a fired electrode layer as the outermost layer will be omitted or simplified.

[0115] Fig. 7 is a cross-sectional view (1) of a multilayer ceramic capacitor including a plating layer as an outermost layer according to an embodiment of the present invention, taken along a plane including the longitudinal direction and the lamination direction. Fig. 8 is a cross-sectional view (2) of another multilayer ceramic capacitor including a plating layer as an outermost layer according to an embodiment of the present invention, taken along a plane including the longitudinal direction and the lamination direction.

[0116] Multilayer ceramic capacitors 10A ( FIG. 7 ) and 10B ( FIG. 8 ) each including a plating layer as the outermost layer include a laminate 12 and an external electrode 30 disposed on the laminate 12. The external electrode 30 includes a baked electrode layer 32 and a plating layer 34 disposed on the baked electrode layer 32. The plating layer 34 is the outermost layer of the multilayer ceramic capacitors 10A and 10B. The configuration other than the plating layer 34 is the same as that of the multilayer ceramic capacitor 10 including the baked electrode layer 32 as the outermost layer. The plating layer 34 is formed by including at least one selected from, for example, Ni, Sn, Cu, Ag, etc. The multilayer ceramic capacitor 10 including the baked electrode layer 32 as the outermost layer does not include a plating layer ( FIG. 3 ).

[0117] The multilayer ceramic capacitors 10A and 10B are formed by performing the steps 1 to 7 of the multilayer ceramic capacitor 10 described above, followed by a step 8 in which a plating layer 34 is disposed on the baked electrode layer 32. In step 8, a plating process is performed to form a first plating layer 34a (first lower-layer plating layer 34a1, first upper-layer plating layer 34a2) on the first baked electrode layer 32a, and a second plating layer 34b (second lower-layer plating layer 34b1, second upper-layer plating layer 34b2) on the second baked electrode layer 32b. The plating layer 34 is formed, for example, by barrel plating. Either electrolytic plating or electroless plating may be used for the plating process. However, electroless plating has the disadvantage of requiring pretreatment using a catalyst or the like to improve plating deposition speed, which complicates the process. Therefore, electrolytic plating is usually preferred.

[0118] Multilayer ceramic capacitors 10A, 10B having a plating layer 34 as the outermost layer are also included in post-sintering waste (sintering for the fired electrode layer), similar to multilayer ceramic capacitors 10 having a fired electrode layer 32 as the outermost layer (sometimes referred to as multilayer ceramic capacitors 10 without a plating layer 34). Furthermore, depending on the material constituting the plating layer 34, multilayer ceramic capacitors 10A, 10B having a plating layer 34 may be introduced into the separation and recovery method shown in FIG. 1A described above, or into the separation and recovery method shown in FIG. 9 described below. While the separation and recovery method shown in FIG. 1A does not include a step of removing the plating layer 34, the separation and recovery method shown in FIG. 9 includes a step of removing the plating layer 34 (step (K)).

[0119] The plating layer 34 may be formed from a single plating layer ( FIG. 7 ), or may be formed by laminating multiple plating layers ( FIG. 8 ). Below, a multilayer ceramic capacitor 10A in which the plating layer 34 is a single plating layer and a multilayer ceramic capacitor 10B in which the plating layer 34 is a multiple plating layer are described. Furthermore, for each of the multilayer ceramic capacitors 10A and 10B, a method for separating and recovering rare earth components and metal components from post-sintering waste of the multilayer ceramic capacitors 10A and 10B having the plating layer 34 as the outermost layer is described.

[0120] 2.1.1. Multilayer Ceramic Capacitor Including a Single Plating Layer (1) Configuration In the multilayer ceramic capacitor 10A shown in FIG. 7, the external electrode 30 includes a baked electrode layer 32 and a plating layer 34 disposed on the baked electrode layer 32. The plating layer 34 is formed of a single plating layer. In the example shown in FIG. 7, the plating layer 34 includes a first lower-layer plating layer (first first-stage plating layer) 34a1 and a second lower-layer plating layer 34b1 (second first-stage plating layer). The first external electrode 30a includes a first baked electrode layer 32a and a first lower-layer plating layer 34a1 on the first baked electrode layer 32a. The second external electrode 30b includes a second baked electrode layer 32b and a second lower-layer plating layer 34b1 on the second baked electrode layer 32b. The first and second lower plating layers 34a1, 34b1 are the outermost layers of the layers disposed on the laminate 12. The baked electrode layer 32 serves as a base for the plating layer 34, and is therefore sometimes referred to as a base electrode layer.

[0121] (2) Separation and Recovery Method (2-1) Overview of the Separation and Recovery Method The multilayer ceramic capacitor 10A having the plating layer 34 is included in the post-sintering waste (sintering for the fired electrode layer), just like the multilayer ceramic capacitor 10 having the fired electrode layer 32 as the outermost layer. Therefore, the multilayer ceramic capacitor 10A having the plating layer 34 can be input into the separation and recovery method of FIG. 1A. That is, in the preparation of the post-sintering waste in step (A), the multilayer ceramic capacitor 10A having the plating layer 34 can be prepared as the post-sintering waste. Thereafter, by going through the separation and recovery method described with reference to FIG. 1A, the first metal component, the second metal component, and the rare earth component can be separated and recovered from the multilayer ceramic capacitor 10A having the plating layer 34.

[0122] 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 from the multilayer ceramic capacitor 10A. Figure 9 is a flow diagram showing a method for separating and recovering rare earth components and metal components from post-fired waste (firing for fired electrode layers) of a multilayer ceramic capacitor having a plating layer 34 as the outermost layer, including a plating removal step. The separation and recovery method of Figure 9 differs from the separation and recovery method of Figure 1A in that it includes a plating removal step (K) for removing the plating layer 34 between the preparation of the post-fired waste in step (A) and the pulverization step (B). The separation and recovery method of Figure 9 is the same as the separation and recovery method of Figure 1A except for the inclusion of step (K).

[0123] In the separation and recovery of various components from the multilayer ceramic capacitor 10A having the plating layer 34, whether to use the separation and recovery method of FIG. 1A which does not include a plating removal step or the separation and recovery method of FIG. 9 which includes a plating removal step can be divided, for example, as follows:

[0124] (2-2) In the case of using a separation and recovery method (FIG. 1A) that does not include a plating removal step, in a multilayer ceramic capacitor 10A having a plating layer 34, the metal component contained in both the first and second lower plating layers 34a1, 34b1 is 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 fired electrode layer 32. In this case, the multilayer ceramic capacitor 10A having the plating layer 34 is prepared as post-sintering waste in step (A) of FIG. 1A and is further processed in each step from step (B) onward of the separation and recovery method shown in FIG. 1A. For example, if the first metal component is contained in both the first and second lower plating layers 34a1, 34b1, the first metal component of the plating layer 34 can be separated and recovered together with the first metal component contained in the internal electrode layer 16. Furthermore, for example, when the second metal component is contained in both the first and second lower plating layers 34a1, 34b1, the second metal component of the plating layer 34 can be separated and recovered together with the second metal component contained in the baked electrode layer 32. It is also possible to separate and recover rare earth components from the ceramic layer 14.

[0125] A more specific example will be described. For example, assume that both the first and second lower plating layers 34a1, 34b1 are plating layers primarily composed of Ni. Furthermore, assume that the internal electrode layer 16 contains Ni as the first metal component. In this case, the multilayer ceramic capacitor 10A is prepared as post-sintering waste in step (A) of FIG. 7A without removing the first and second lower plating layers 34a1, 34b1. Thereafter, by undergoing each step from step (B) onward in the separation and recovery method of FIG. 1A, the first metal component, Ni, can be separated and recovered from the first and second lower plating layers 34a1, 34b1 and the internal electrode layer 16. Note that the second metal component can be separated and recovered from the fired electrode layer 32, and the rare earth component can be separated and recovered from the ceramic layer 14.

[0126] As another example, assume that both the first and second lower plating layers 34a1, 34b1 are plating layers primarily composed of Cu. Furthermore, assume that the baked electrode layer 32 contains Cu as the second metal component. In this case, the multilayer ceramic capacitor 10A is prepared as post-sintering waste in step (A) of FIG. 7A without removing the first and second lower plating layers 34a1, 34b1. Thereafter, by undergoing step (B) and subsequent steps of the separation and recovery method of FIG. 1A, the second metal component, Cu, can be separated and recovered from the first and second lower plating layers 34a1, 34b1 and the baked electrode layer 32. The first metal component can be separated and recovered from the internal electrode layer 16, and the rare earth component can be separated and recovered from the ceramic layer 14.

[0127] (2-3) Separation and Recovery Method Including a Plating Removal Step (FIG. 9) In a multilayer ceramic capacitor 10A having a plating layer 34, the metal components contained in both the first and second lower plating layers 34a1, 34b1 are different from both the first metal component contained in the internal electrode layer 16 and the second metal component contained in the fired electrode layer 32. In other words, the metal component (third metal component) contained in the first and second lower plating layers 34a1, 34b1 is different from both the first metal component and the second metal component. In this case, the multilayer ceramic capacitor 10A having the plating layer 34 is prepared as post-sintering waste in step (A) of FIG. 3. Then, the first and second lower plating layers 34a1, 34b1 are removed by plating removal in step (K). Thereafter, the multilayer ceramic capacitor 10A from which the plating layer 34 has been removed is further processed in step (B) and subsequent steps of the separation and recovery method shown in FIG. 9. This allows the first metal component constituting the internal electrode layer 16, the second metal component constituting the baked electrode layer 32, and the rare earth component contained in the ceramic layer 14 to be separated and recovered from the multilayer ceramic capacitor 10A from which the plating layer 34 has been removed.

[0128] A more specific example will be described. For example, suppose both the first and second lower plating layers 34a1, 34b1 are plating layers primarily composed of Sn (an example of a third metal component). Furthermore, suppose the internal electrode layer 16 contains Ni as the first metal component, and the fired electrode layer 32 contains Cu as the second metal component. In this case, the multilayer ceramic capacitor 10A having the plating layer 34 is prepared as post-sintering waste in step (A) of FIG. 9 . Then, in step (K) of FIG. 9 , the first and second lower plating layers 34a1, 34b1 primarily composed of Sn are removed. The first and second lower plating layers 34a1, 34b1 primarily 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 water, such as sodium hydroxide or potassium hydroxide. In this case, the fired electrode layer 32 primarily composed of Cu is exposed to the alkaline solution after the plating layer 34 is removed. However, the baked electrode layer 32, which is mainly composed of Cu, is not easily corroded by the alkaline solution. Here, the alkaline solution other than ammonia water is adjusted to, for example, a pH of about 12. Thereafter, by going through each step from step (B) of the separation and recovery method in Figure 9 onwards, it is possible to separate and recover the first metal component constituting the internal electrode layer 16, the second metal component constituting the baked electrode layer 32, and the rare earth component contained in the ceramic layer 14.

[0129] In the above example, the Sn-based plating layer 34 is removed using an alkaline solution other than ammonia water. However, the Sn-based plating layer 34 can also be removed using an acidic solution with no oxidizing power, such as hydrochloric acid or dilute sulfuric acid. In this case, the Cu-based baked electrode layer 32 is exposed to the acidic solution when the plating layer 34 is removed. However, the Cu-based baked electrode layer 32 is not easily corroded by the acidic solution. Here, the acidic solution is adjusted to, for example, a pH of approximately 2.

[0130] Note that even when the metal components contained in both the first and second lower plating layers 34a1, 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 fired electrode layer 32, the multilayer ceramic capacitor 10A having the plating layer 34 may be prepared as waste after firing in step (A) of Fig. 9. Then, the first and second lower plating layers 34a1, 34b1 may be removed by plating removal in step (K).

[0131] For example, suppose both the first and second lower plating layers 34a1, 34b1 are Ni-based. Furthermore, suppose the internal electrode layer 16 contains Ni as the first metal component, and the baked electrode layer 32 contains Cu as the second metal component. In this case, the multilayer ceramic capacitor 10A having the plating layer 34 is prepared as post-sintering waste in step (A) of FIG. 9 . Then, in step (K) of FIG. 9 , the Ni-based first and second lower plating layers 34a1, 34b1 are removed. The Ni-based first and second lower plating layers 34a1, 34b1 can be removed by immersing the multilayer ceramic capacitor 10A having the plating layer 34 in a non-oxidizing acidic solution, such as hydrochloric acid or dilute sulfuric acid. In this case, the Cu-based baked electrode layer 32 is exposed to the acidic solution after the plating layer 34 is removed. However, the baked electrode layer 32, which is primarily composed of Cu, is not easily corroded by the acidic solution. Here, the acidic solution is adjusted to, for example, a pH of about 2. Thereafter, by going through each step from step (B) of the separation and recovery method in Figure 9 onwards, it is possible to separate and recover the first metal component constituting the internal electrode layer 16, the second metal component constituting the baked electrode layer 32, and the rare earth component contained in the ceramic layer 14.

[0132] 2.1.2. Multilayer Ceramic Capacitor Including Multiple Plating Layers (1) Configuration In a multilayer ceramic capacitor 10B shown in FIG. 8, the external electrode 30 includes a baked electrode layer 32 and a plating layer 34 disposed on the baked electrode layer 32. The plating layer 34 is formed from multiple plating layers. In the example shown in FIG. 8, the plating layer 34 is formed from two plating layers. Specifically, the plating layer 34 includes a first lower-layer plating layer (first first-stage plating layer) 34a1 and a second lower-layer plating layer (second first-stage plating layer) 34b1, as well as a first upper-layer plating layer (first second-stage plating layer) 34a2 and a second upper-layer plating layer (second second-stage plating layer) 34b2. The first external electrode 30a includes a first baked electrode layer 32a, a first lower-layer plating layer 34a on the first baked electrode layer 32a, and a first upper-layer plating layer 34a on the first lower-layer plating layer 34a. The second external electrode 30b includes a second baked electrode layer 32b, a second lower-layer plating layer 34b on the second baked electrode layer 32b, and a second upper-layer plating layer 34b on the second lower-layer plating layer 34b. The first upper-layer plating layer 34a and the second upper-layer plating layer 34b are the outermost layers arranged on the laminate 12.

[0133] The multilayer ceramic capacitor 10B having a plating layer 34 as the outermost layer is formed by performing (Step 1) to (Step 7) of the multilayer ceramic capacitor 10 having a baked electrode layer as the outermost layer, followed by a step (Step 8) of disposing the plating layer 34 on the baked electrode layer 32. In (Step 8), a plating process is performed to sequentially form a first lower-layer plating layer 34a1 and a first upper-layer plating layer 34a2 on the first baked electrode layer 32a, and a second upper-layer plating layer 34b2 on the second lower-layer plating layer 34b1 on the second baked electrode layer 32b.

[0134] (2) Separation and Recovery Method (2-1) Overview of the Separation and Recovery Method The multilayer ceramic capacitor 10B having the plating layer 34 is included in the post-sintering waste (sintering for the fired electrode layer), just like the multilayer ceramic capacitor 10 having the fired electrode layer 32 as the outermost layer. Therefore, the multilayer ceramic capacitor 10B having the plating layer 34 can be input into the separation and recovery method of FIG. 1A. That is, in the preparation of the post-sintering waste in step (A), the multilayer ceramic capacitor 10B having the plating layer 34 can be prepared as the post-sintering waste. Thereafter, by going through the separation and recovery method described with reference to FIG. 1A, the first metal component, the second metal component, and the rare earth component can be separated and recovered from the multilayer ceramic capacitor 10B having the plating layer 34.

[0135] However, it is also possible to remove the plating layer 34 from the multilayer ceramic capacitor 10B having the plating layer 34, and then recover the first metal component, the second metal component, and the rare earth component from the multilayer ceramic capacitor 10B.

[0136] In the separation and recovery of various components from the multilayer ceramic capacitor 10B having the plating layer 34, whether to use the separation and recovery method of FIG. 1A which does not include a plating removal step or the separation and recovery method of FIG. 9 which includes a plating removal step can be divided, for example, as follows:

[0137] (2-2) When a separation and recovery method (FIG. 1A) not including a plating removal step is used: In a multilayer ceramic capacitor 10B having a plating layer 34, the metal components contained in the first and second lower plating layers 34a1, 34b1 and the first and second upper plating layers 34a2, 34b2 are the same as at least one of the first metal component contained in the internal electrode layer 16 and the second metal component contained in the baked electrode layer 32. In this case, the multilayer ceramic capacitor 10B having the plating layer 34 is prepared as waste after firing in step (A) of FIG. 7A and treated by the separation and recovery method shown in FIG. 1A. For example, the metal components of the first and second lower plating layers 34a1, 34b1 may be the same as the first metal component contained in the internal electrode layer 16. Furthermore, the metal components of the first and second upper plating layers 34a2, 34b2 may be the same as the second metal component contained in the baked electrode layer 32. Alternatively, for example, the metal components of the first and second lower plating layers 34a1, 34b1 may be the same as the second metal component contained in the baked electrode layer 32. Furthermore, the metal components of the first and second upper plating layers 34a2, 34b2 may be the same as the first metal component contained in the internal electrode layer 16. In this case, the first and second metal components of the plating layer 34 can be separated and recovered together with the first metal component contained in the internal electrode layer 16 and the second metal component contained in the baked electrode layer 32. Note that rare earth components can be separated and recovered from the ceramic layer 14.

[0138] Further explanation will be given by way of a specific example. For example, suppose the first and second lower plating layers 34a1, 34b1 are plating layers primarily composed of Ni (or Cu). Furthermore, suppose the first and second upper plating layers 34a2, 34b2 are plating layers primarily composed of Cu (or Ni). Furthermore, suppose the internal electrode layer 16 contains Ni as a first metal component. Furthermore, suppose the fired electrode layer 32 contains Cu as a second metal component. In this case, the multilayer ceramic capacitor 10B is prepared as post-firing waste in step (A) of FIG. 1A without the first and second lower plating layers 34a1, 34b1 and the first and second upper plating layers 34a2, 34b2 being removed. 1A, by going through each step from step (B) onwards, it is possible to separate and recover the first metal component Ni and the second metal component Cu from the first and second lower plating layers 34a1, 34b1, the first and second upper plating layers 34a2, 34b2, the internal electrode layer 16, and the baked electrode layer 32. It is also possible to separate and recover rare earth components from the ceramic layer 14.

[0139] (2-3) Separation and Recovery Method Including Plating Removal Step (FIG. 9) As an example, in a multilayer ceramic capacitor 10B having a plating layer 34, the metal component (third metal component) contained in the first and second lower plating layers 34a1, 34b1 and the first and second upper plating layers 34a2, 34b2 is different from both the first metal component contained in the internal electrode layer 16 and the second metal component contained in the fired electrode layer 32. In this case, the multilayer ceramic capacitor 10B having the plating layer 34 is prepared as post-sintering waste in step (A) of FIG. 9. Then, the first and second lower plating layers 34a1, 34b1 and the first and second upper plating layers 34a2, 34b2 are removed by plating removal in step (K). Thereafter, the multilayer ceramic capacitor 10B from which the plating layer 34 has been removed is further processed in step (B) and subsequent steps of the separation and recovery method shown in FIG. 9. This allows the first metal component constituting the internal electrode layer 16, the second metal component constituting the baked electrode layer 32, and the rare earth component contained in the ceramic layer 14 to be separated and recovered from the multilayer ceramic capacitor 10B from which the plating layer 34 has been removed.

[0140] As another example, in a multilayer ceramic capacitor 10B having a plating layer 34, the (third metal component) contained in the first and second upper plating layers 34a, 34b is different from both the first metal component contained in the internal electrode layer 16 and the second metal component contained in the baked electrode layer 32. Meanwhile, the metal components contained in the first and second lower plating layers 34a, 34b are the same as either the first metal component contained in the internal electrode layer 16 or the second metal component contained in the baked electrode layer 32. In this case, the multilayer ceramic capacitor 10B having the plating layer 34 is prepared as post-sintering waste in step (A) of FIG. 9 . Then, the first and second upper plating layers 34a, 34b are removed by plating removal in step (K). The multilayer ceramic capacitor 10B from which the first and second upper plating layers 34a, 34b have been removed is then further processed in step (B) and subsequent steps of the separation and recovery method shown in FIG. 9 . As a result, from the multilayer ceramic capacitor 10B from which the first and second upper plating layers 34a2, 34b2 have been removed, it is possible to separate and recover the metal components (first metal component or second metal component) contained in the first and second lower plating layers 34a1, 34b1, the first metal component constituting the internal electrode layer 16, the second metal component constituting the fired electrode layer 32, and the rare earth component contained in the ceramic layer 14.

[0141] The above-mentioned other example will be further described with a specific example. For example, suppose the metal component contained in the first and second upper plating layers 34a2, 34b2 is a plating layer containing Sn (an example of a third metal component) as the main component. Also, suppose the metal component contained in the first and second lower plating layers 34a1, 34b1 is a plating layer containing Ni (or Cu) as the main component. Furthermore, suppose the internal electrode layer 16 contains Ni as the first metal component, and the fired electrode layer 32 contains Cu as the second metal component. In this case, the multilayer ceramic capacitor 10B having the plating layer 34 is prepared as waste after firing in step (A) of FIG. 9 . Then, in step (K) of FIG. 9 , the first and second upper plating layers 34a2, 34b2 containing Sn as the main component are removed. The first and second upper plating layers 34a, 34b, primarily composed of Sn, can be removed by immersing the multilayer ceramic capacitor 10B having the plating layers 34 in an alkaline solution other than aqueous ammonia, such as sodium hydroxide or potassium hydroxide. In this case, the first and second lower plating layers 34a, 34b, primarily composed of Ni (or Cu), are exposed to the alkaline solution as the first and second upper plating layers 34a, 34b are removed. However, the first and second lower plating layers 34a, 34b, primarily composed of Ni (or Cu), are not easily corroded by the alkaline solution. Furthermore, the baked electrode layer 32, primarily composed of Cu, is also not easily corroded by the alkaline solution. The alkaline solution other than aqueous ammonia is adjusted to, for example, a pH of approximately 12. 9 , the first metal component Ni and the second metal component Cu can be separated and recovered from the first and second lower plating layers 34a1, 34b1, the internal electrode layer 16, and the baked electrode layer 32. Rare earth components can also be separated and recovered from the ceramic layer 14.

[0142] In the above example, only the first and second upper plating layers 34a, 34b are removed in step (K). However, both the first and second upper plating layers 34a, 34b and the first and second lower plating layers 34a, 34b may be removed. For example, suppose the metal component contained in the first and second upper plating layers 34a, 34b is primarily Sn (an example of a third metal component). Also, suppose the metal component contained in the first and second lower plating layers 34a, 34b is primarily Ni rather than Cu. Furthermore, suppose the internal electrode layer 16 contains Ni as the first metal component, and the fired electrode layer 32 contains Cu as the second metal component. In this case, the multilayer ceramic capacitor 10B having the plating layer 34 is prepared as post-sintering waste in step (A) of FIG. 9 . Then, in step (K) of FIG. 9 , the first and second upper plating layers 34a2, 34b2, primarily composed of Sn, and the first and second lower plating layers 34a1, 34b1, primarily composed of Ni, are removed. The first and second upper plating layers 34a2, 34b2, primarily composed of Sn, and the first and second lower plating layers 34a1, 34b1, primarily composed of Ni, can be removed by immersing the multilayer ceramic capacitor 10B having the plating layers 34 in a non-oxidizing acidic solution, such as hydrochloric acid or dilute sulfuric acid. In this case, the baked electrode layer 32, primarily composed of Cu, is exposed to the acidic solution as the plating layers 34 are removed. However, the baked electrode layer 32, primarily composed of Cu, is not easily corroded by the acidic solution. Here, the acidic solution is adjusted to, for example, a pH of approximately 2. 9 , the first metal component Ni and the second metal component Cu can be separated and recovered from the internal electrode layer 16 and the fired electrode layer 32. The rare earth component can be separated and recovered from the ceramic layer 14.

[0143] In the above process, the first and second upper plating layers 34a, 34b, each primarily composed of Sn, and the first and second lower plating layers 34a, 34b, each primarily composed of Ni, are simultaneously removed using a non-oxidizing acidic solution. However, they may also be removed sequentially. First, the multilayer ceramic capacitor 10B is immersed in an alkaline solution (e.g., about pH 12) other than aqueous ammonia, such as sodium hydroxide or potassium hydroxide, to remove the first and second upper plating layers 34a, 34b. Then, the multilayer ceramic capacitor 10B is immersed in a non-oxidizing acidic solution (e.g., about pH 2), such as hydrochloric acid or dilute sulfuric acid, to remove the first and second lower plating layers 34a, 34b, each primarily composed of Ni. 9 , the first metal component Ni and the second metal component Cu can be separated and recovered from the internal electrode layer 16 and the fired electrode layer 32. The rare earth component can be separated and recovered from the ceramic layer 14.

[0144] 2.2. Effects As with the multilayer ceramic capacitor 10 having a baked electrode layer 32 as the outermost layer, the first metal component constituting the internal electrode layer 16, the second metal component constituting the external electrode 30, and the rare earth component contained in the ceramic layer 14 can be separated and recovered from the multilayer ceramic capacitors 10A, 10B having the plating layer 34 as the outermost layer by the separation and recovery method shown in Fig. 1A or 9. Furthermore, by employing a separation and recovery method suitable for separating and recovering the metal components from the plating layer 34, the first metal component and the second metal component can sometimes be recovered from the plating layer 34 as well.

[0145] As described above, although the embodiments of the present invention have been disclosed in the above description, the present invention is not limited thereto. In other words, various modifications can be made to the above-described embodiments in terms of mechanism, shape, material, quantity, position, arrangement, etc., without departing from the scope of the technical idea and purpose of the present invention, and such modifications are included in the present invention.

[0146] 3. Other Modifications

[0147] A modified example applicable to both the separation and recovery method for post-fired waste from a multilayer ceramic capacitor 10 having a fired electrode layer 32 as the outermost layer and the separation and recovery method for post-fired waste from multilayer ceramic capacitors 10A and 10B having a plating layer 34 as the outermost layer will be described below. (1) Generation of Slurry Using an Aqueous Solvent in Step (B) In the above embodiment, the post-fired waste is pulverized and refined in step (B). However, as long as the post-fired waste can be refined, the post-fired waste may be dispersed in a solvent (e.g., an aqueous solvent) to form a slurry. This refinement, in which the post-fired waste is mixed with a solvent to form a slurry, is referred to as wet refinement. Among wet refinement methods, the refinement in which the post-fired waste is pulverized in a slurry formed by mixing the post-fired waste with a solvent, is referred to as wet grinding. Note that, for example, water can be used as the aqueous solvent.

[0148] Furthermore, in the above embodiment, during magnetic separation in step (C), the calcined waste after being pulverized in step (B) can be mixed with and dispersed in an aqueous solvent such as water to form a slurry. However, as described above, if the calcined waste is pulverized using an aqueous solvent in addition to or instead of pulverization in step (B), the slurried calcined waste may be magnetically separated in step (C). In other words, the effort of generating a slurry in the magnetic separation in step (C) can be omitted.

[0149] It is also possible to prepare a slurry of the post-calcination waste using an organic solvent. However, when the post-calcination waste is prepared in a slurry form using an organic solvent, a step of removing the organic solvent is required in the separation and recovery method. Therefore, it is preferable to prepare a slurry of the post-calcination waste using an aqueous solvent such as water.

[0150] (2) Other Examples of Post-Firing Waste In the above-described embodiment, the post-firing waste refers to waste that has undergone the firing for the fired electrode layers in (Step 7). However, the post-firing waste is not limited to this. The post-firing waste may also include waste that has not yet undergone the firing for the fired electrode layers, but has been fired before being input into the separation and recovery methods of FIGS. 1A and 9. In this case, the firing is preferably carried out at the firing temperature used in the firing for the fired electrode layers.

[0151] Examples of waste before firing for the fired electrode layers include waste discharged in (Step 1) to (Step 6). Furthermore, waste before firing for the fired electrode layers may include waste after the paste for the fired electrode layers has been applied to the laminate 12 in (Step 7) but before firing for the fired electrode layers has been performed. Specifically, examples of waste before firing for the fired electrode layers include waste of dielectric slurry and conductive paste for the internal electrode layers in (Step 1), waste of dielectric sheets on which the patterns of the internal electrode layers have been formed and dielectric sheets on which the patterns of the internal electrode layers are not printed in (Step 2), excess laminate blocks such as scraps of laminate blocks discharged after cutting the laminate blocks in (Step 4), and defective laminate chips after cutting, waste after degreasing in (Step 5), and waste after firing of the laminate chips in (Step 6).

[0152] (3) Other Multilayer Ceramic Capacitors for Which Post-Firing Waste is Discharged In the above embodiments, a two-terminal multilayer ceramic capacitor having two terminals, a first external electrode 30a and a second external electrode 30b, has been described as the multilayer ceramic capacitor to be manufactured. However, the scope of application of the present invention is not limited to post-firing waste from two-terminal multilayer ceramic capacitors. The present invention is applicable to post-firing waste from multilayer ceramic capacitors having internal electrode layers containing a first metal component such as Ni, external electrodes containing a second metal component such as Cu, and ceramic layers containing a dielectric material such as BaTiO3 and a rare earth component as an additive such as Dy. Therefore, the present invention may also be applied to post-firing waste from three-terminal multilayer ceramic capacitors, for example.

[0153] For example, a three-terminal multilayer ceramic capacitor may include a laminate 12 similar to that of the above-described embodiment and first to fourth external electrodes. The internal electrode layers 16 include a first internal electrode layer extending to the first end face 12e and the second end face 12f, and a second internal electrode layer extending to the first side face 12c and the second side face 12d. A first external electrode is disposed on the first end face 12e of the laminate 12. The first external electrode is electrically connected to the first internal electrode layer exposed at the first end face 12e of the laminate 12. A second external electrode is disposed on the second end face 12f of the laminate 12. The second external electrode is electrically connected to the first internal electrode layer exposed at the second end face 12f of the laminate 12. A third external electrode is disposed on the first side face 12c of the laminate 12. The third external electrode is electrically connected to the second internal electrode layer exposed at the first side face 12c of the laminate 12. A fourth external electrode is disposed on the second side surface 12d of the laminate 12. The fourth external electrode is electrically connected to the second internal electrode layer exposed on the second side surface 12d of the laminate 12. The first to fourth external electrodes may include only a baked electrode layer, or may include a baked electrode layer and a plated layer.

[0154] (4) Regarding the filtration step (F), when the second separated material is dissolved in a non-oxidizing mineral acid in step (D), the ceramic fine particles contained in the second separated material react with the non-oxidizing mineral acid to form undissolved particles and precipitate. Furthermore, the second metal fine particles, such as Cu, do not dissolve in the non-oxidizing mineral acid because they have a lower ionization tendency than the hydrogen ions contained in the non-oxidizing mineral acid. Meanwhile, the rare earth components in the rare earth-containing material dissolve to produce a rare earth component-containing solution. The rare earth component-containing solution containing the undissolved particles can also be recovered as the rare earth components. In this case, the solid-liquid separation step (F), such as filtration, can be omitted.

[0155] (5) Omission of Neutralization in Step (G) In the above embodiment, the rare earth components can be separated and recovered as a rare earth component-containing solution in the dissolution of the second separated product in Step (D), so the neutralization in Step (G) can be omitted.

[0156] (6) Omission of Various Treatments in Step (I) In the above embodiment, the first metal component can be separated and recovered in the electrolytic refining in Step (H), so that the various treatments in Step (I) can be omitted.

[0157] (7) Other methods for separating and recovering rare earth components In the above-described embodiment, rare earth component compounds such as Dy(OH) are separated and recovered as rare earth components in the neutralization step (G). However, the method for separating and recovering rare earth components is not limited to this. For example, the rare earth components can be recovered as follows.

[0158] (a) The rare earth component compound obtained by the neutralization in step (G) is heat-treated to produce an oxide, which can be recovered as a rare earth component. For example, if the rare earth component compound obtained after the neutralization in step (G) is Dy(OH), dysprosium oxide (DyO) can be recovered as a rare earth component by heat-treating Dy(OH).

[0159] (b) The rare earth component compound obtained by the neutralization in step (G) is dissolved in hydrochloric acid to produce a chloride, which can be recovered as a rare earth component. For example, if the rare earth component compound obtained after the neutralization in step (G) is Dy(OH), a dysprosium chloride (DyCl) solution is produced by dissolving Dy(OH) in hydrochloric acid. The dysprosium chloride solution is distilled off to evaporate the solvent, and dysprosium chloride hexahydrate (DyCl.6H0) can be recovered as a rare earth component.

[0160] (c) As in (b) above, a dysprosium chloride solution is produced by dissolving Dy(OH)3, the rare earth component compound obtained after neutralization in step (G), in hydrochloric acid. This can then be further purified to recover a high-purity rare earth component. For example, the dysprosium chloride solution produced as described above can be purified by solvent extraction, and a high-purity dysprosium chloride solution can be recovered as a rare earth component. Solvent extraction is a separation and purification method that utilizes solute partitioning, in which a solute dissolved in one of the immiscible liquids, an oil phase and an aqueous phase, is transferred to the other. Methods other than solvent extraction, such as an ion exchange resin method, can also be used.

[0161] (d) High-purity dysprosium oxide (DyO) can also be recovered from the high-purity dysprosium chloride solution obtained by the solvent extraction described in (c) above. In this case, for example, oxalic acid is first added to the high-purity dysprosium chloride solution to precipitate dysprosium oxalate. This is then filtered to recover high-purity dysprosium oxalate hexahydrate (Dy(C0)6H0). By heat-treating this high-purity dysprosium oxalate hexahydrate, high-purity dysprosium oxide (DyO) can be recovered as a rare earth component.

[0162] (e) High-purity dysprosium chloride hexahydrate can also be recovered from the high-purity dysprosium chloride solution obtained by the solvent extraction described in (c) above. In this case, for example, high-purity dysprosium chloride hexahydrate is recovered by distilling off the high-purity dysprosium chloride solution and evaporating the solvent.

[0163] (f) In the above embodiment, the rare earth component-containing solution separated and recovered in the filtration of step (F) is introduced into the neutralization of step (G). However, the rare earth component-containing solution separated and recovered in the filtration of step (F) may be treated in a rare earth component concentration step and then introduced into the neutralization of step (G). In other words, the rare earth component concentration step is performed after the filtration of step (F) and before the neutralization of step (G).

[0164] The rare earth component concentration step is not limited as long as it can improve the recovery amount of the rare earth component in the rare earth component-containing solution. Examples of the rare earth component concentration step include, but are not limited to, (f1) ion exchange method, (f2) solvent extraction method, and (f3) distillation of the solvent from the solution. Each of (f1) to (f3) will be described below as a representative example.

[0165] (f1) Ion Exchange Method: The ion exchange method is a method in which dissolved ions in a solvent are adsorbed onto an ion exchanger such as an ion exchange resin or a chelating resin. For example, by passing a solution containing rare earth components through an ion exchanger, the rare earth components in the solution are adsorbed onto the ion exchanger. The ion exchange method is not limited, but may be carried out, for example, by passing the solution containing rare earth components through a column packed with an ion exchanger. For example, the column is formed of a cylindrical body with open top and bottom ends, and the solution containing rare earth components is introduced into the column from the top side of the column, and the rare earth components are adsorbed onto the ion exchanger during the process of passing through the ion exchanger. The remaining solution containing rare earth components after passing through the ion exchanger is discharged from the bottom side of the column.

[0166] Next, the rare earth components adsorbed on the ion exchanger are eluted from the ion exchanger using an eluent. For example, the eluent is passed through the lower end of a column packed with the ion exchanger on which the rare earth components are adsorbed. As a result, the rare earth components are eluted from the ion exchanger by the eluent. The eluent containing the eluted rare earth components is recovered from the upper end of the column. The rare earth components can be recovered by filtering the eluent containing the dissolved rare earth components, for example, using a filter. Depending on the processing volume of the rare earth component-containing solution, the ease of adsorption of the rare earth components to the ion exchanger, the amount of eluent, and other factors, the concentration of the rare earth components contained in the eluent can be made higher than the concentration of the rare earth components contained in the rare earth component-containing solution.

[0167] In the above example, the rare earth component-containing solution is passed through the column from the top to the bottom, and then the eluent is passed through the column from the bottom to the top. However, the direction in which the rare earth component-containing solution and the eluent are passed through the column is not limited as long as the rare earth components can be dissolved in the eluent after being adsorbed onto the ion exchanger.

[0168] Alternatively, the series of steps (1) including steps (A) to (F) and the rare earth component concentration step by ion exchange may be carried out only once. For example, the series of steps (1) is carried out only once by passing the rare earth component-containing solution after steps (A) to (F) through an ion exchanger once.

[0169] Alternatively, a series of steps (1) including steps (A) to (F) and a rare earth component concentration step by ion exchange may be performed multiple times. For example, the series of steps (1) in which the rare earth component-containing solution after steps (A) to (F) is passed through an ion exchanger may be performed multiple times. In this case, the same ion exchanger may be used in each series of steps (1). By passing the rare earth component-containing solution recovered from steps (A) to (F) multiple times through the same ion exchanger, more rare earth components are adsorbed onto the ion exchanger than in the rare earth component-containing solution recovered from a single run of steps (A) to (F). This increases the concentration of the rare earth components in the eluent and increases the amount of rare earth components recovered.

[0170] Alternatively, a series of steps (2) including steps (A) to (F) may be performed multiple times, and the rare earth component-containing solution obtained in each series of steps (2) may then be temporarily stored. The stored rare earth component-containing solution may then be processed all at once in a rare earth component concentration step using ion exchange. The amount of rare earth component-containing solution stored after multiple series of steps (2) is greater than the amount of rare earth component-containing solution obtained from a single series of steps (2). Therefore, by passing the stored rare earth component-containing solution through an ion exchanger, a larger amount of rare earth component can be adsorbed onto the ion exchanger, thereby increasing the amount of rare earth component recovered.

[0171] In addition, if the concentration of rare earth components in the rare earth component-containing solution after one cycle of the series of steps (A) to (F) in step (2) is low, the amount of rare earth components deposited on the filter will be small even if the rare earth component-containing solution is filtered using a filter. Therefore, the recovery amount of the rare earth components may not be high. However, the recovery amount of the rare earth components can be increased by performing the rare earth component concentration step as described above.

[0172] Examples of ion exchange resins that serve as ion exchangers include, but are not limited to, cation exchange resins and chelating resins. Examples of cation exchange resins include, but are not limited to, gel-type cation exchange resins, strong acid cation exchange resins, and weak acid cation exchange resins. Specific examples of cation exchange resins include, but are not limited to, Amberlite IR-120B (manufactured by Organo Corporation), Duolite C20J (manufactured by Sumika Chemtex Co., Ltd.), DIAION SK-110 (manufactured by Mitsubishi Chemical Corporation), and Purolite C100 (manufactured by Purolite Co., Ltd.).

[0173] Examples of chelating resins that are ion exchangers include, but are not limited to, resins having chelating groups or chelating capabilities such as thiourea groups, thiouronium groups, phosphonic acid, aminophosphoric acid, aminocarboxylic acid, alkylamino groups, pyridine rings, cyclic cyanines, and cyclic ethers. Specific examples of chelating resins include, but are not limited to, Sumichelate MC700 (manufactured by Sumika Chemtex Co., Ltd.) and Purolite MTS9300 (manufactured by Purolite Co., Ltd.).

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

[0175] In the back-extraction step, the rare earth-containing water-insoluble organic phase obtained through the phase separation step is brought into contact with and mixed with an acidic aqueous solution, thereby allowing the rare earth components in the water-insoluble organic phase to be back-extracted into the acidic aqueous solution.

[0176] Alternatively, the series of steps (1) including steps (A) to (F) and the step of concentrating the rare earth components by solvent extraction may be carried out only once.

[0177] Alternatively, a series of steps (1) including steps (A) to (F) and a rare earth component concentration step by solvent extraction may be performed multiple times. For example, a series of steps (1) in which the rare earth component-containing solution after steps (A) to (F) is mixed with an organic solvent may be performed multiple times. For example, by repeatedly mixing the rare earth component-containing solution recovered from steps (A) to (F) multiple times with the same organic solvent, more rare earth components are transferred to the organic solvent than when the rare earth component-containing solution recovered from steps (A) to (F) is mixed with an organic solvent once. Therefore, the amount of rare earth components recovered can be increased.

[0178] Alternatively, a series of steps (2) including steps (A) to (F) may be carried out multiple times, and the rare earth component-containing solution obtained in each series of steps (2) may be temporarily stored. Thereafter, the stored rare earth component-containing solution may be treated all at once in a rare earth component concentration step using a solvent extraction method.

[0179] (f3) Removal of solvent from solution Removal of solvent from solution involves removing the solvent from a solution containing dissolved ions. Removal of the solvent can be performed using, for example, but not limited to, an evaporator. An evaporator is a device that evaporates the solvent by, for example, heating and reducing the pressure inside an evaporator into which the solution has been introduced. Examples of evaporators include rotary evaporators and flash evaporators. The operating conditions of the evaporator are appropriately adjusted depending on the amount of unburned waste to be processed before or after the production and degreasing, the various components added to the unburned waste, and the like.

[0180] Furthermore, the series of steps (1) including steps (A) to (F) and the step of concentrating the rare earth component by distilling off the solvent from the solution may be carried out only once or may be carried out multiple times.

[0181] Alternatively, a series of steps (2) including steps (A) to (F) may be carried out multiple times, and the rare earth component-containing solution obtained in each series of steps (2) may be temporarily stored. Thereafter, the stored rare earth component-containing solution may be treated all at once to distill off the solvent.

[0182] (g) State of rare earth component The recovered rare earth component may be in a liquid state, a solid state, or a mixture of liquid and solid. The crystal lattice of the rare earth component may be in an amorphous state, a crystalline state, or a mixture of amorphous and crystalline states.

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

[0184] (a) In the various treatments of step (I), the first metal component and the solution are reacted to each other, and the first metal component compound is thereby crystallized to recover the first metal component. For example, if the first metal solution obtained after the various treatments of step (I) is a nickel sulfate (NiSO4) solution, nickel sulfate hexahydrate (NiSO4.6H2O) can be recovered as the first metal component by crystallizing and filtering the nickel sulfate solution.

[0185] (b) A high-purity first metal component can be recovered by purifying the first metal solution obtained by reacting the first metal component with the solution in the various treatments of step (I). For example, a nickel sulfate (NiSO4) solution, which is the first metal solution, can be purified by an ion exchange resin method, a solvent extraction method, or the like, and a high-purity nickel sulfate solution can be recovered as the first metal component.

[0186] (c) The high-purity nickel sulfate solution recovered in (b) above is crystallized and filtered to recover nickel sulfate hexahydrate (NiSO4.6H2O) as the first metal component.

[0187] (d) By treating the high-purity Ni recovered by the electrolytic refining in step (H), nickel chloride hexahydrate (NiCl.6H0) can be recovered as the first metal component. For example, by dissolving the high-purity Ni recovered by the electrolytic refining in step (H) in hydrochloric acid, a high-purity nickel chloride (NiCl) solution is produced. By spray-drying the nickel chloride solution, high-purity nickel chloride hexahydrate is produced. By further drying the high-purity nickel chloride hexahydrate with hot air, even higher-purity nickel chloride hexahydrate can be recovered as the first metal component.

[0188] (e) The first metal solution, which is the reaction between the metal component and the solution in the various treatments of step (I), can be neutralized to produce a chloride, which can then be recovered as the first metal component. For example, the nickel sulfate solution, which is the first metal solution, is neutralized by adjusting the pH to, for example, about pH 10 (pH 9 or higher and pH 11 or lower) with an alkali such as sodium hydroxide or potassium hydroxide, thereby precipitating nickel hydroxide (Ni(OH)). The precipitated nickel hydroxide (Ni(OH)) can be separated and recovered, for example, by filtration. Furthermore, nickel hydroxide is dissolved in hydrochloric acid to produce a nickel chloride (NiCl) solution. Next, nickel chloride hexahydrate (NiCl.6H0) can be recovered as the first metal component by distilling off the nickel chloride solution and evaporating the solvent.

[0189] (f) State of the First Metal Component The recovered metal component may be in a liquid state, a solid state, or a mixture of liquid and solid. The crystal lattice of the metal component may be in an amorphous state, a crystalline state, or a mixture of amorphous and crystalline states.

[0190] (9) Other Manufacturing Processes for the Multilayer Ceramic Capacitor In the above embodiment, the manufacturing method for the multilayer ceramic capacitor 10 includes, in order, forming a laminate block (step 3), cutting into laminate chips (step 4), degreasing (step 5), firing the laminate chips (step 6), and applying and firing a baking electrode layer paste (step 7). However, the manufacturing method for the multilayer ceramic capacitor 10 is not limited to this. For example, before the degreasing (step 5) and before the firing (firing of the laminate chips) (step 6), a baking electrode layer paste may be applied to the unfired laminate chips, followed by degreasing and firing of the baking electrode layers. That is, first, a baking electrode layer paste containing Ni, glass components, resin components, etc. is applied to the laminate chips before degreasing (step 5). Next, the laminate chips coated with the baking electrode layer paste are degreased, and then the baking electrode layers are fired. The temperature during degreasing is preferably, for example, higher than 800°C and lower than 1000°C. The firing temperature for the fired electrode layers is preferably, for example, higher than 1000° C. and not higher than 1400° C. These steps are performed after cutting into laminated chips in step 4 of the above-mentioned manufacturing method and before the plating step in step 8. In these steps, the firing of the laminated chips in step 6 and the firing of the paste for the fired electrode layers in step 7 are performed in a single firing.

[0191] <1> (A) a step of preparing fired waste of a multilayer ceramic capacitor, the fired waste being waste after firing of the fired electrode layers of the multilayer ceramic capacitor, the multilayer ceramic capacitor including a laminate including ceramic layers and internal electrode layers, and fired electrode layers disposed on the laminate as outermost layers and connected to the internal electrode layers, the ceramic layers having aggregates of a plurality of ceramic particles, a rare earth-containing material containing a rare earth component being contained in grain boundaries between the plurality of ceramic particles, the internal electrode layers containing a first metal component which is a magnetic base metal, the fired electrode layers containing a second metal component which is a non-magnetic noble metal, and the ceramic layers, the internal electrode layers, and the fired electrode layers being sintered; (B) a step of micronizing the fired waste to obtain a ceramic micronized material obtained by micronizing the ceramic layers, the rare earth-containing material, a first metal micronized material obtained by micronizing the internal electrode layers, and a second metal micronized material obtained by micronizing the fired electrode layers; (C) using a magnet to separate and recover the fired waste after the step (B) into a first separated material containing the ceramic fine particle and the first metal fine particle, and a second separated material containing the ceramic fine particle, the rare earth-containing material, and the second metal fine particle; and (H) recovering the first metal component from the first separated material after the step (C) by electrolytic refining.

[0192] <2> The method for separating and recovering rare earth elements and metal elements from post-sintering waste of multilayer ceramic capacitors according to <1>, wherein the metal powder-containing material is introduced into the step (H) in a state where the metal powder has been processed into a mass in which the metal powders are in contact with each other to an extent that current can flow in the electrolytic refining.

[0193] <3> The method for separating and recovering rare earth components and metal components from post-sintering waste of multilayer ceramic capacitors according to <1> or <2>, wherein in the step (C), the post-sintering waste pulverized in the step (B) is mixed with an aqueous solvent to produce a slurry, and then the first separated matter and the second separated matter are recovered using the magnet.

[0194] <4> The method for separating and recovering rare earth components and metal components from post-sintering waste of multilayer ceramic capacitors according to any one of <1> to <3>, further comprising the step of: (D) dissolving the second separated product after the step (C) in at least one mineral acid having no oxidizing power selected from the group consisting of dilute sulfuric acid and hydrochloric acid, thereby precipitating the ceramic finely divided product and the second metal finely divided product in the second separated product and producing a rare earth component-containing solution in which the rare earth component in the rare earth-containing product is dissolved.

[0195] <5> The method for separating and recovering rare earth components and metal components from post-sintering waste of multilayer ceramic capacitors according to <4>, wherein in the step (D), the rare earth component-containing solution is adjusted to a pH of 1.5 or more and 2.5 or less by adding the mineral acid having no oxidizing power.

[0196] <6> (E) The method for separating and recovering rare earth components and metal components from post-sintering waste of multilayer ceramic capacitors according to <4> or <5>, further comprising the step of dissolving the ceramic microparticles and the second metal microparticles in the second separated product precipitated in the step (D) in ammonia water to precipitate the ceramic microparticles in the second separated product and to produce a second metal solution in which the second metal component contained in the second metal microparticles is dissolved.

[0197] <7> The method for separating and recovering rare earth components and metal components from post-sintering waste of multilayer ceramic capacitors according to <6>, wherein in the step (E), the second metal solution is adjusted to a pH of 9 or more and 10 or less by adding the ammonia water.

[0198] <8> The method for separating and recovering rare earth components and metal components from post-sintering waste of multilayer ceramic capacitors according to any one of <4> to <7>, further comprising: (F) a step of performing solid-liquid separation on the rare earth component-containing solution containing the precipitated ceramic microparticles and the undissolved second metal microparticles.

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

[0200] <10> The method for separating and recovering rare earth elements and metal elements from post-sintering waste of multilayer ceramic capacitors according to any one of <1> to <9>, wherein the first metal element is Ni.

[0201] <11> The method for separating and recovering rare earth elements and metal elements from post-sintering waste of multilayer ceramic capacitors according to any one of <1> to <10>, wherein the second metal element is Cu.

[0202] <12> The method for separating and recovering rare earth elements and metal elements from post-sintering waste of multilayer ceramic capacitors according to <1> or <2>, wherein the ceramic particles are BaTiO3.

[0203] <13> The method for separating and recovering rare earth components and metal components from post-sintering waste of multilayer ceramic capacitors according to any one of <1> to <12>, wherein the rare earth component is at least one of Dy, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb, and Lu.

[0204] <14> (A) a step of preparing fired waste of a multilayer ceramic capacitor, the fired waste being for fired electrode layers of the multilayer ceramic capacitor, the multilayer ceramic capacitor including: a laminate including ceramic layers and internal electrode layers; fired electrode layers disposed on the laminate and connected to the internal electrode layers; and a first-stage plating layer disposed on the fired electrode layers as an outermost layer, the ceramic layers having aggregates of a plurality of ceramic particles, wherein rare earth-containing substances containing rare earth components are contained in grain boundaries between the plurality of ceramic particles; the internal electrode layers contain a first metal component which is a magnetic base metal; the fired electrode layers contain a second metal component which is a non-magnetic noble metal; the first-stage plating layer contains the first metal component; and the ceramic layers, the internal electrode layers, and the fired electrode layers are sintered; (B) micronizing the fired waste to obtain a ceramic micronized product in which the ceramic layer has been micronized, a first metal micronized product in which the rare earth-containing material, the internal electrode layer, and the first-stage plating layer have been micronized, and a second metal micronized product in which the baked electrode layer has been micronized; (C) using a magnet to separate and recover the fired waste after the step (B) into a first separated product containing the ceramic micronized product and the first metal micronized product, and a second separated product containing the ceramic micronized product, the rare earth-containing material, and the second metal micronized product; and (H) recovering the first metal component from the first separated product after the step (C) by electrolytic refining.

[0205] <15> (A) a step of preparing fired waste of a multilayer ceramic capacitor, the fired waste being for fired electrode layers of the multilayer ceramic capacitor, the multilayer ceramic capacitor including: a laminate including ceramic layers and internal electrode layers; fired electrode layers disposed on the laminate and connected to the internal electrode layers; a first-stage plating layer disposed on the fired electrode layers; and a second-stage plating layer disposed on the first-stage plating layer as an outermost layer, the ceramic layers having aggregates of a plurality of ceramic particles, and rare earth-containing substances containing rare earth components are contained in grain boundaries between the plurality of ceramic particles; the internal electrode layers contain a first metal component which is a magnetic base metal; the fired electrode layers contain a second metal component which is a non-magnetic noble metal; the first-stage plating layer contains the first metal component; the second-stage plating layer contains a third metal component; and the ceramic layers, the internal electrode layers, and the fired electrode layers are sintered; (K) removing at least the second-stage plating layer from the fired waste, of the first-stage plating layer and the second-stage plating layer; (B) micronizing the fired waste from which at least the second-stage plating layer has been removed by passing through the step (K) to obtain a ceramic micronized product in which the ceramic layer has been micronized, the rare earth-containing material, a first metal micronized product in which the internal electrode layer and the first-stage plating layer have been micronized, and a second metal micronized product in which the baked electrode layer has been micronized; (C) using a magnet to separate and recover the fired waste after passing through the step (B) into a first separated product containing the ceramic micronized product and the first metal micronized product, and a second separated product containing the ceramic micronized product, the rare earth-containing material, and the second metal micronized product; (H) recovering the first metal component from the first separated product after passing through the step (C) by electrolytic refining; The method for separating and recovering rare earth elements and metal elements from post-sintering waste of multilayer ceramic capacitors comprises:

[0206] 10, 10A, 10B: Multilayer ceramic capacitor 12: Laminate 12a: First main surface 12b: Second main surface 12c: First side surface 12d: Second side surface 12e: First end surface 12f: Second end surface 14: Ceramic layer 14_U: Unsintered ceramic layer 16: Internal electrode layer 16_U: Unsintered internal electrode layer 16a: First internal electrode layer 16b: Second internal electrode layer 30: External electrode 30a: First external electrode 30b: Second external electrode 32: Baked electrode layer 32a: First base electrode layer, first baked electrode layer 32b: Second base electrode layer, second baked electrode layer 34: Plating layer 34a: First plating layer 34b: Second plating layer 34a1: First lower plating layer 34a2: First upper plating layer 34b1: Second lower plating layer 34b2: Second upper plating layer 40: Core-shell 42: Core portion 44: Shell portion 50: Grain boundary 60: Electrolytic refining system 61: Electrolytic cell 61a: Electrolyte 62: Anode 63: Cathode 64: Power source 65: Anode basket 65a: Object to be treated x: Height direction y: Width direction z: Length direction

Claims

1. (A) a process for preparing fired waste of a multilayer ceramic capacitor, the fired waste being waste after firing of the fired electrode layer of the multilayer ceramic capacitor, the multilayer ceramic capacitor comprising a laminate including ceramic layers and internal electrode layers, and fired electrode layers disposed on the laminate as outermost layers and connected to the internal electrode layers, the ceramic layers comprising aggregates of a plurality of ceramic particles, rare earth-containing materials containing rare earth components being contained in grain boundaries between the plurality of ceramic particles, the internal electrode layers comprising a first metal component which is a magnetic base metal, the fired electrode layers comprising a second metal component which is a non-magnetic noble metal, the ceramic layers, the internal electrode layers, and the fired electrode layers being sintered; (B) a process for pulverizing the fired waste to obtain a ceramic pulverized material obtained by pulverizing the ceramic layer, the rare earth-containing materials, a first metal pulverized material obtained by pulverizing the internal electrode layers, and a second metal pulverized material obtained by pulverizing the fired electrode layers; (C) using a magnet to separate and recover the fired waste after the step (B) into a first separated material containing the ceramic fine particle and the first metal fine particle, and a second separated material containing the ceramic fine particle, the rare earth-containing material, and the second metal fine particle; and (H) recovering the first metal component from the first separated material after the step (C) by electrolytic refining.

2. A method for separating and recovering rare earth elements and metal elements from post-sintering waste of multilayer ceramic capacitors as set forth in claim 1, wherein the metal powder-containing material is introduced into step (H) in a state where it has been processed into a mass in which the metal powder particles are in contact with each other to the extent that current can flow in the electrolytic refining.

3. A method for separating and recovering rare earth components and metal components from post-sintering waste of multilayer ceramic capacitors as described in claim 1 or claim 2, wherein in step (C), the post-sintering waste that has been pulverized in step (B) is mixed with an aqueous solvent to produce a slurry, and then the first separated product and the second separated product are recovered using the magnet.

4. A method for separating and recovering rare earth components and metal components from post-sintering waste of multilayer ceramic capacitors as described in any one of claims 1 to 3, further comprising the step of (D) dissolving the second separated product after step (C) in at least one mineral acid having no oxidizing power selected from the group consisting of dilute sulfuric acid and hydrochloric acid, thereby precipitating the ceramic fine particles and the second metal fine particles in the second separated product and producing a rare earth component-containing solution in which the rare earth components in the rare earth-containing material are dissolved.

5. A method for separating and recovering rare earth components and metal components from post-sintering waste of multilayer ceramic capacitors as set forth in claim 4, wherein in step (D), the pH of the rare earth component-containing solution is adjusted to 1.5 or more and 2.5 or less by adding the mineral acid having no oxidizing power.

6. (E) A method for separating and recovering rare earth components and metal components from post-sintering waste of multilayer ceramic capacitors as described in claim 4 or claim 5, further comprising a step of dissolving the ceramic microparticles and the second metal microparticles in the second separated product precipitated in step (D) in ammonia water, thereby precipitating the ceramic microparticles in the second separated product and producing a second metal solution in which the second metal component contained in the second metal microparticles is dissolved.

7. A method for separating and recovering rare earth elements and metal elements from post-sintering waste of multilayer ceramic capacitors according to claim 6, wherein in step (E), the second metal solution is adjusted to a pH of 9 or more and 10 or less by adding the ammonia water.

8. (F) A method for separating and recovering rare earth components and metal components from post-sintering waste of multilayer ceramic capacitors as described in any one of claims 4 to 7, further comprising a step of solid-liquid separation of the rare earth component-containing solution containing the precipitated ceramic fine particles and the undissolved second metal fine particles.

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

10. A method for separating and recovering rare earth elements and metal elements from post-sintering waste of multilayer ceramic capacitors according to any one of claims 1 to 9, wherein the first metal element is Ni.

11. A method for separating and recovering rare earth elements and metal elements from post-sintering waste of multilayer ceramic capacitors according to any one of claims 1 to 10, wherein the second metal element is Cu.

12. A method for separating and recovering rare earth elements and metal elements from post-sintering waste of multilayer ceramic capacitors according to claim 1 or 2, wherein the ceramic particles are BaTiO3.

13. A method for separating and recovering rare earth components and metal components from post-sintering waste of multilayer ceramic capacitors according to any one of claims 1 to 12, wherein the rare earth component is at least one of Dy, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb, and Lu.

14. (A) A process of preparing fired waste for a multilayer ceramic capacitor, the fired waste comprising: a laminate including a ceramic layer and an internal electrode layer; a fired electrode layer disposed on the laminate and connected to the internal electrode layer; and a first-stage plating layer disposed on the fired electrode layer as an outermost layer; the ceramic layer having an aggregate of a plurality of ceramic particles, the grain boundaries between the plurality of ceramic particles containing rare earth elements, the internal electrode layer containing a first metal component which is a magnetic base metal; the fired electrode layer containing a second metal component which is a non-magnetic noble metal; the first-stage plating layer containing the first metal component; and the ceramic layer, the internal electrode layer, and the fired electrode layer being sintered; (B) micronizing the fired waste to obtain a ceramic micronized product in which the ceramic layer has been micronized, a first metal micronized product in which the rare earth-containing material, the internal electrode layer, and the first-stage plating layer have been micronized, and a second metal micronized product in which the baked electrode layer has been micronized; (C) using a magnet to separate and recover the fired waste after the step (B) into a first separated product containing the ceramic micronized product and the first metal micronized product, and a second separated product containing the ceramic micronized product, the rare earth-containing material, and the second metal micronized product; and (H) recovering the first metal component from the first separated product after the step (C) by electrolytic refining.

15. (A) A process of preparing fired waste from a multilayer ceramic capacitor, the fired waste being a fired waste for a fired electrode layer of a multilayer ceramic capacitor comprising: a laminate including a ceramic layer and an internal electrode layer; a fired electrode layer disposed on the laminate and connected to the internal electrode layer; a first-stage plating layer disposed on the fired electrode layer; and a second-stage plating layer disposed on the first-stage plating layer as an outermost layer, the ceramic layer having an aggregate of a plurality of ceramic particles, the grain boundaries between the plurality of ceramic particles containing rare earth elements, the internal electrode layer containing a first metal component which is a magnetic base metal, the fired electrode layer containing a second metal component which is a non-magnetic noble metal, the first-stage plating layer containing the first metal component, the second-stage plating layer containing a third metal component, and the ceramic layer, the internal electrode layer, and the fired electrode layer being sintered; (K) removing at least the second-stage plating layer from the fired waste, of the first-stage plating layer and the second-stage plating layer; (B) micronizing the fired waste from which at least the second-stage plating layer has been removed by passing through the step (K) to obtain a ceramic micronized product in which the ceramic layer has been micronized, the rare earth-containing material, a first metal micronized product in which the internal electrode layer and the first-stage plating layer have been micronized, and a second metal micronized product in which the baked electrode layer has been micronized; (C) using a magnet to separate and recover the fired waste after passing through the step (B) into a first separated product containing the ceramic micronized product and the first metal micronized product, and a second separated product containing the ceramic micronized product, the rare earth-containing material, and the second metal micronized product; (H) recovering the first metal component from the first separated product after passing through the step (C) by electrolytic refining; The method for separating and recovering rare earth elements and metal elements from post-sintering waste of multilayer ceramic capacitors comprises:

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