JP2014181884A - External heat type rotary kiln - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an external heat type rotary kiln for preventing contamination of chromium or the like at the time of heat treatment of powder electrode material and restricting a reduction in battery characteristics.SOLUTION: Since a cylindrical outer pipe 52 has an inner peripheral layer 52b composed of pure nickel (Ni) having a reactivity resistance against lithium, nickel, cobalt, manganese and the like at its inside part, for example, even if a lithium component and a part of nickel component of a powder-like electrode material enters into a clearance between the outer pipe 52 and an inner pipe 54 to contact a layer-like inner peripheral layer 52b formed inside the outer pipe 52, it does not react with pure nickel constituting the inner peripheral layer 52b and does not produce hexavalent chromium and the like. Due to this fact, hexavalent chromium and the like are not mixed at the time of heat treatment of the powder-like electrode material and a reduction of battery characteristics of a lithium battery in which the powder-like anode material is applied as an anode substance is restricted.

Description

  The present invention relates to an externally heated rotary kiln having a cylindrical furnace core tube, and more particularly to a technique for suppressing contaminants mixed in a powder material to be heat-treated.

  The externally heated rotary kiln has (a) a cylindrical outer tube made of a metallic material containing chromium and a cylindrical inner tube made of a ceramic material inserted inside the outer tube, and is horizontally oriented. (B) Heat treatment and transfer of the powdered electrode material introduced into the core tube by heating from the outside while rotating the core tube around the axis. There is something to do. For example, it is shown in patent document 1.

  Moreover, in the externally heated rotary kiln of Patent Document 1, the inner tube is a cylindrical shape in which a male screw portion is formed on the outer periphery of one end portion in the axial direction and a female screw portion is formed on the inner periphery of the other end portion. A plurality of partial tubes are connected in the axial direction by screwing of the male screw portion and the female screw portion.

JP 2012-117722 A

  By the way, in the external heating type rotary kiln as described above, when the powdered electrode material is heat-treated, a small amount of property-decreasing substance such as hexavalent chromium is mixed in the powdered electrode material after the heat treatment, and the heat treatment is performed. There was a problem that the battery characteristics of the battery using the powdered electrode material deteriorated.

  As a result of various analyzes and examinations, the present inventor has reached the facts shown below. That is, the outer tube made of a heat-resistant steel tube and the inner tube made of a ceramic material constituting the core tube of the externally heated rotary kiln as described above are not integrated because of their different expansion rates. A slight gap is formed between the inner tube and the outer tube, and the outer tube expands larger than the inner tube by heat treatment, and a larger gap is repeatedly formed between the inner tube and the outer tube. For this reason, the powdered electrode material enters the gap and comes into contact with the heat resistant steel pipe of the outer tube, so that the powdered electrode material reacts with the chromium contained in the heat resistant steel pipe and contains a small amount of chromium. become. Then, as the core tube rotates, the powdered electrode material containing chromium moves to the outlet side of the core tube, and, for example, male threads that are screwed together in a plurality of partial tubes constituting the inner tube It was estimated that a very small amount would be mixed into the powdered electrode material inside the inner tube through the gap between the screw part and the female screw part.

  The present invention has been made against the background of the above circumstances, and provides an externally heated rotary kiln that prevents a minute amount of chromium or the like from being mixed during heat treatment of a powdered electrode material and suppresses deterioration of battery characteristics. With the goal.

  As a result of repeated various analyzes and examinations, the present inventor found that pure nickel is resistant to lithium, nickel, cobalt, manganese, etc., and in the above external heat type rotary kiln, the chromium of the outer tube was found. It was found that forming an inner peripheral layer made of pure nickel inside a heat-resistant steel pipe containing, suitably suppresses deterioration in characteristics of a battery using the powdered electrode material as an electrode, and completed the present invention. .

  That is, the gist of the present invention is (a) a cylindrical outer tube made of a metal material containing chromium and a cylindrical inner tube made of a ceramic material inserted inside the outer tube, A cylindrical core tube inclined with respect to the horizontal direction is provided, and the core tube is heated from the outside while rotating around the axis, thereby heat-treating the powdered electrode material charged in the core tube and It is an external heating type rotary kiln that performs transfer, and (b) the cylindrical outer tube has an inner peripheral layer made of pure nickel inside thereof.

  According to the externally heated rotary kiln of the present invention, the cylindrical outer tube has an inner peripheral layer made of pure nickel on the inside thereof. For example, a part of the powdered electrode material is formed between the outer tube and the inner tube. Even if it enters the gap with the tube and comes into contact with the layered inner peripheral layer formed inside the outer tube, it does not react with the pure nickel constituting the inner peripheral layer and does not contain a trace amount of chromium. For this reason, the fall of the battery characteristic using the heat-treated powdery electrode material is suppressed.

  Here, it is preferable that the inner peripheral layer of the cylindrical outer pipe is formed by inserting a metal pipe made of pure nickel inside the outer pipe and performing a hot isostatic pressing method on the inner peripheral surface of the outer pipe. It is joined to. For this reason, even if the temperature change of the said core tube occurs at the time of the operation | movement of the said external-heat type rotary kiln and a stop, peeling of the said inner peripheral layer from the inner side of the said outer tube is prevented suitably.

It is a side view explaining the structure of the external heating type rotary kiln which is one Example of this invention. It is the II-II sectional view taken on the line of FIG. FIG. 3 is a sectional view taken along line III-III in FIG. 1. FIG. 2 is a cross-sectional view cut along a plane including the axis to describe in detail the configuration of the core tube provided in the externally heated rotary kiln of FIG. 1. It is the enlarged view to which the area | region enclosed by the dashed-dotted line shown by FIG. FIG. 5 is a process diagram illustrating an example of a manufacturing process of an outer tube in the core tube, which is a part of the manufacturing process of the core tube shown in FIG. 4.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a side view illustrating a configuration of an externally heated rotary kiln 10 that is an embodiment of the present invention. 2 is a sectional view taken along the line II-II, and FIG. 3 is a sectional view taken along the line III-III. As shown in FIG. 1, an externally heated rotary kiln 10 according to the present embodiment includes a frame 12 installed on a floor surface, a pedestal 14 provided on the frame 12, and a raw material supply device provided on the pedestal 14. 16, the heat processing apparatus 18, and the product discharge apparatus 20 are comprised. As will be described later, the externally heated rotary kiln 10 includes a cylindrical core tube 34 (which is horizontal in FIG. 1) that is inclined at an angle of, for example, about 1 ° with respect to the horizontal direction. It is a heating furnace (rotary cylindrical pot) that heats and transfers the object to be heated put in the core tube 34 by heating from the outside by the heat treatment device 18 while rotating the 34 around the axis. In addition, the object to be heated that is heat-treated in the externally heated rotary kiln 10 is, for example, a powdered electrode material for synthesizing a positive electrode active substance of a lithium battery by heat treatment (firing) and solid-phase reaction. The powdered electrode material is, for example, a powdered lithium component for producing lithium nickelate (LiNiO ₂ ) and a mixed powder of the powdered nickel component, for producing lithium cobaltate (LiCoO ₂ ). A powder mixture of a powdered lithium component and a powdered cobalt component, or a powder mixture of a powdered lithium component and a powdered manganese component for producing lithium manganate (LiMn ₂ O ₄ ) Lithium battery material.

The pedestal 14 is formed into a longitudinal plate shape by, for example, steel, and is a fulcrum provided on the destination (exit) side of the object to be heated in the longitudinal direction (axial direction of the core tube 34). The part 22 is supported so as to be rotatable around the fulcrum part 22 with respect to the frame 12. Further, the pedestal 14 is arranged in a vertical direction (vertical direction) with respect to the frame 12 in an elevating part 24 by a screw mechanism or a hydraulic cylinder provided on the front side (inlet) of the heated object in the longitudinal direction. It is movable (movable up and down), that is, its distance from the frame 12 is supported to be adjustable. The pedestal 14 is raised and lowered with respect to the frame 12 by the elevating part 24, and the distance between the frame 12 and the pedestal 14 in the elevating part 24 is adjusted, so that the pedestal 14 is moved around the fulcrum part 22. The tilt angle of the pedestal 14 with respect to the horizontal direction and the tilt angle θ _fc with respect to the horizontal direction of the core tube 34 shown in FIG. 4 to be described later can be adjusted (changed).

  The raw material supply device 16 is provided on the front (inlet) side of the heated object in the longitudinal direction of the pedestal 14, and includes a supply hopper 26 that receives the raw material, that is, the heated object, and the supply hopper 26. And an input feeder 28 for feeding the object to be heated supplied to the heat treatment apparatus 18. The charging feeder 28 includes a motor 30 and a screw device 32 that is driven to rotate about the axis by the motor 30, and the end of the screw device 32 opposite to the motor 30 is the heat treatment device. 18 is inserted into the core tube 34. Then, the screw device 32 is rotated around the axis by the motor 30, whereby the powdery object to be heated supplied to the supply hopper 26 is sequentially and continuously transferred toward the heat treatment device 18. The heat treatment apparatus 18 is charged into a furnace core tube 34.

  The heat treatment device 18 is supported by the roller devices 36a and 36b (hereinafter simply referred to as the roller device 36 unless otherwise specified) provided at both ends so that the heat treatment device 18 can rotate (spin) around the axis with respect to the frame 12. And a heating chamber 38 provided outside the core tube 34, and a drive device 40 for rotating the core tube 34 about its axis.

  For example, as shown in FIGS. 1 and 3, the heating chamber 38 is a longitudinal rectangular parallelepiped housing provided outside the core tube 34 so as to surround a major portion excluding both ends of the core tube 34. A heating device such as an infrared heater is provided in the body, and the core tube 34 is capable of relative rotation (spinning) around the axis with respect to the heating chamber 38. 1 and 2, for example, the drive device 40 is coaxial with the motor 42, the sprocket 44 attached to the output shaft of the motor 42, and the outer peripheral side of the furnace core tube 34, and is not relatively rotatable. And a chain 48 wound between the sprockets 44 and 46. In the driving apparatus 40 configured as described above, the core tube 34 is rotated (rotated) around its axis through the sprockets 44 and 46 and the chain 48 by driving the motor 42.

  The product discharge device 20 is provided on the destination (exit) side of the object to be heated in the longitudinal direction of the pedestal 14, and the end of the object to be heated in the furnace tube 34 on the destination side in the transfer direction Is provided, and the bottom is configured in a funnel shape. The object to be heated that has been subjected to the heat treatment in the heat treatment apparatus 18 is discharged into the product discharge apparatus 20 through the opening by the transfer accompanying the rotation of the furnace core tube 34, and further through a funnel-shaped structure provided at the bottom thereof. The product is then discharged into a product receiving tank 50 installed below.

In the externally heated rotary kiln 10 configured as described above, the distance between the frame 12 and the pedestal 14 is adjusted in the elevating part 24, and the pedestal 14 is shown by a two-dot chain line in FIG. The powdered object to be heated is heat-treated in a state where it is inclined at a predetermined inclination angle θ _fc (for example, about 1 °) with respect to the horizontal direction. That is, an object to be heated, which is a raw material supplied to the supply hopper 26 of the raw material supply device 16, is fed into the core tube 34 of the heat treatment device 18 by the input feeder 28, and the core tube 34 is connected to the heat treatment device 18. By being heated from the outside by the heating chamber 38 while being rotated about its axis by the driving device 40, the object to be heated put in the core tube 34 is heat-treated and transferred. Then, an object to be heated which is a product subjected to heat treatment in the heat treatment device 18 is discharged from the furnace tube 34 into the product discharge device 20 and further discharged to the product receiving tank 50. As described above, for example, a positive electrode material of a lithium battery, for example, lithium nickelate, in which a powdered electrode material (object to be heated) such as a lithium component and a nickel component is heat-treated in the core tube 34 and synthesized by a solid phase reaction. Is generated.

  FIG. 4 is a cross-sectional view cut along a plane including the axis to describe in detail the configuration of the core tube 34 provided in the externally heated rotary kiln 10 of the present embodiment. As shown in FIG. 4, the core tube 34 provided in the external heating rotary kiln 10 includes a cylindrical outer tube 52 and a cylindrical inner tube 54 inserted inside the outer tube 52. It is prepared for. That is, the core tube 34 provided in the externally heated rotary kiln 10 of this embodiment has a double structure of the outer tube 52 and the inner tube 54 inserted inside the outer tube 52. Further, as shown in FIG. 4, the inner tube 54 has a plurality (for example, 14) of which an external thread 58 is formed on the outer periphery of one end in the axial direction and an internal thread 60 is formed on the inner periphery of the other end. , 56n (hereinafter simply referred to as the partial tube 56 unless otherwise specified), the end surfaces on the inner peripheral side of the cylindrical partial tubes 56a, 56b, 56c,. 57 (see FIG. 5) are connected in the axial direction by screwing of the male screw portion 58 and the female screw portion 60 until they abut against each other.

FIG. 5 is an enlarged view in which a region A surrounded by a dot-dash line in FIG. 4 and surrounded by a circle is enlarged. As shown in FIGS. 4 and 5, the outer tube 52 includes a cylindrical heat-resistant steel tube 52a made of a metal material that can withstand a firing temperature of 850 to 950 ° C., such as a nickel-based alloy containing chromium such as Inconel. And an inner peripheral layer 52b in which pure nickel is formed in layers on the entire inner side of the heat-resistant steel pipe 52a, for example, a cylindrical shape (tubular) having an inner diameter of about 234 mmφ, a thickness of about 13 mm, and a length of about 3 m. It has been done. The inner tube 54 is formed by molding a raw material prepared by mixing a ceramic material such as alumina and a slight amount of an inorganic binder, for example, by cold isostatic pressing or CIP (Cold Isostatic Pressing) called isostatic pressing. Then, it is manufactured by firing. In addition, the external thread part 58 and the internal thread part 60 formed in the inner tube 54 are formed by cutting with a thread cutting tool or the like after the firing. The inner tube 54 is made of a ceramic material with alumina (Al ₂ O ₃ ) of about 99.7% by weight, for example, a cylindrical shape having an outer diameter of about 232 mmφ, a thickness of about 20 mm, and a length of about 3 m ( (Tubular).

  In the core tube 34 in the externally heated rotary kiln 10 of the present embodiment, as shown in FIG. 4, the male screw part 58 and the female screw part 60 in the mutually adjacent partial pipes 56 are screwed together, so that the axial center C direction. A plurality of partial pipes 56 are connected to form an inner pipe 54. Then, the inner tube 54 is inserted into the inner periphery of the outer tube 52, and the annular lid members 64 and 66 are fitted to both ends thereof, so that the inner tube 54 can move relative to the outer tube 52 in the axial direction. It is blocked. In FIG. 4, the lid member 66 is fixed to the inner tube 54 by a pin 68 on the product discharger 20 side, that is, the destination (exit) side of the object to be heated, and a claw provided on the outer periphery thereof. The portion 70 is hooked on the outer tube 52. The lid member 64 is fixed to the outer tube 52 by a bolt 72 on the screw device 32 side of the raw material supply device 16, that is, on the front side (inlet) side of the object to be heated. The position of the inner tube 54 is fixed between the lid members 64 and 66 by a spring 74 provided between the inner tube 54 and the loosening of the screwing of the male screw portion 58 and the female screw portion 60 is further suppressed. It is like that.

  FIG. 6 is a process diagram illustrating an example of the manufacturing process of the outer tube 52, which is a part of the manufacturing process of the core tube 34. According to FIG. 6, first, in a process P1 of inserting a Ni pipe into a steel pipe, a cylindrical pure nickel pipe having an outer diameter smaller than the inner diameter of a cylindrical heat resistant steel pipe 52a made of, for example, Inconel or the like is purified. It is made by bending from a nickel (for example, JIS H4551, NW2201) plate material, and the pure nickel pipe is inserted into the heat resistant steel pipe 52a. In this example, the pure nickel is JIS H4551 NW2201 equivalent, for example, the chemical component [mass%] is C ≦ 0.02, Si ≦ 0.35, Mn ≦ 0.35, S ≦ 0.01. Ni ≧ 99.0, Fe ≦ 0.40, Cu ≦ 0.25 are preferable, and high purity Ni with Ni ≧ 95.0% may be used.

  Next, in the HIP forming step P2, a high temperature of 1100 ° C. and an isotropic pressure of 1000 atm, for example, are simultaneously applied from the inside of the pure nickel tube for 2 hours by hot isostatic pressing, that is, HIP (Hot Isostatic Pressing). In addition, an inner peripheral layer 52b made of pure nickel is formed inside the heat resistant steel pipe 52a by joining the pure nickel pipe inside the heat resistant steel pipe 52a. In some cases, after the HIP molding step P2, the inner peripheral layer 52b may be cut by machining in order to set the thickness of the inner peripheral layer 52b to a predetermined value.

  Next, in the welding process P3, a plurality of cylindrical heat-resistant steel pipes 52a formed with the inner circumferential layer 52b formed in the HIP forming process P2 are welded so as to have a predetermined length dimension, for example, about 3 m. The ends of the steel pipe 52a are connected. As a result, the outer tube 52 is manufactured.

  In the externally heated rotary kiln 10 configured as described above, for example, the lithium component and the powdered electrode material of the nickel component before the lithium nickelate is heat-treated are the outer tube 52 and the inner tube on the inlet side of the core tube 34. 54, even if it comes into contact with the inner peripheral layer 52b formed inside the outer tube 52 and enters the gap with the outer tube 52, it does not react with the pure nickel constituting the inner peripheral layer 52b. When the material contacts the outer tube 52, the inner peripheral layer 52b prevents contact with the heat-resistant steel tube 52a containing chromium, so that the reaction between the powdered electrode material and chromium is prevented, and the core tube 34 is prevented. Generation | occurrence | production and mixing of the characteristic degradation material which degrades the battery characteristics of lithium batteries, such as hexavalent chromium, are prevented in the powdered electrode material.

  As described above, according to the externally heated rotary kiln 10 of the present embodiment, the cylindrical outer tube 52 has pure nickel (Ni) that is resistant to lithium, nickel, cobalt, manganese, and the like inside thereof. Therefore, for example, a part of the lithium component and nickel component of the powder electrode material enters the gap between the outer tube 52 and the inner tube 54 and is molded inside the outer tube 52. Even if it comes into contact with the layered inner peripheral layer 52b, it does not react with the pure nickel constituting the inner peripheral layer 52b, and hexavalent chromium or the like is not generated. For this reason, hexavalent chromium or the like is not mixed during the heat treatment of the powdered electrode material, and a decrease in battery characteristics of a lithium battery using the powdered electrode material as a positive electrode material is suppressed.

  Further, according to the externally heated rotary kiln 10 of the present embodiment, the inner peripheral layer 52b of the cylindrical outer tube 52 is inserted with a pure nickel tube made of pure nickel inside the outer tube 52, and isotropically hot. It is joined to the inner peripheral surface of the outer tube 52 by a pressurizing method. For this reason, even if the temperature change of the core tube 34 occurs when the external heating type rotary kiln 10 is operated and stopped, the inner peripheral layer 52b is preferably prevented from peeling off from the inside of the outer tube 52.

  The preferred embodiments of the present invention have been described in detail with reference to the drawings. However, the present invention is not limited to these embodiments, and may be implemented in other modes.

  In the above-described embodiments, the powdered electrode material is used for a lithium battery, but the present invention is applied to a powdered electrode material used for a battery other than a lithium battery, for example. be able to.

  In the above-described embodiment, the inner peripheral layer 52b of the heat-resistant steel pipe 52a is formed by hot isostatic pressing, but the inner peripheral layer 52b is formed by other methods such as electroplating. It may be formed by.

  In the above-described embodiment, the heating chamber 38 is for performing heat treatment on the powdered electrode material by a heating device such as an infrared heater, but the present invention is not limited to this. The apparatus may be a gas burner, an oil burner, an electric heater or the like. In short, the mode is not limited as long as it is a heating device capable of performing sufficient heating for the heat treatment of the powder electrode material.

  In addition, although not illustrated one by one, the present invention is implemented with various modifications within a range not departing from the gist thereof.

10: Externally heated rotary kiln 34: Core tube 52: Outer tube 52b: Inner circumferential layer 54: Inner tube

Claims (2)

A cylindrical core tube having a cylindrical outer tube made of a metal material containing chromium and a cylindrical inner tube made of a ceramic material inserted inside the outer tube and inclined with respect to the horizontal direction. An external heating type rotary kiln that heats and transfers the powdered electrode material charged into the core tube by heating from outside while rotating the core tube about the axis,
The external heating rotary kiln characterized in that the cylindrical outer tube has an inner peripheral layer made of pure nickel inside.   The inner peripheral layer of the cylindrical outer tube is joined to the inner peripheral surface of the outer tube by hot isostatic pressing with a metal tube made of pure nickel inserted inside the outer tube. 1 Externally heated rotary kiln.

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