Preparation device for superfine copper powder

Abstract

The utility model relates to the technical field of preparation devices, and particularly discloses a preparation device for superfine copper powder. The preparation device comprises a reaction kettle, a particle size analyzer and a computer, wherein the reaction kettle comprises a feeding end and a discharging end; the discharge end comprises a plurality of discharge ports arranged at intervals, the particle size analyzer is connected with part of the discharge ports, part of the discharge ports are connected with one end of the electromagnetic valve, and the other end of the electromagnetic valve is connected with the computer; the feeding end comprises a copper precursor feeding port, a reducing agent feeding port and a tangential feeding port, and the tangential feeding port is connected with the remaining discharging ports. The reaction kettle further comprises a gas inlet, a gas distributor is arranged in the reaction kettle, and the gas distributor is connected with the gas inlet of the reaction kettle. The device provided by the utility model is suitable for continuous industrial production of high-purity and narrow-particle-size-distribution copper powder for conductive paste.

Description

Technical Field

[0001] This application relates to the field of preparation apparatus technology, specifically to an apparatus for preparing ultrafine copper powder. Background Technology

[0002] Ultrafine copper powder is a nano-copper material with good conductivity and high strength. Due to its excellent electrical properties, it is widely used in conductive adhesives, conductive coatings and electrode materials.

[0003] Currently, the main methods for preparing ultrafine copper powder in China include traditional methods such as gas condensation, electrolysis, atomization, liquid-phase reduction, and hydrogen reduction. These methods lack a dynamic classification mechanism during the reaction process and cannot effectively control the uniformity of copper powder particles. Utility Model Content

[0004] This application aims to address at least one of the technical problems existing in the prior art. To this end, this application proposes an apparatus for preparing ultrafine copper powder. This apparatus is suitable for the continuous industrial production of high-purity, narrow-particle-size copper powder for conductive pastes.

[0005] A first aspect of this application provides an apparatus for preparing ultrafine copper powder, the apparatus comprising:

[0006] The reactor includes a feed end and a discharge end; the discharge end includes multiple discharge ports arranged at intervals.

[0007] Particle size analyzer: connecting part of the discharge port;

[0008] The aforementioned discharge port is connected to one end of a solenoid valve, and the other end of the solenoid valve is connected to a computer.

[0009] The aforementioned feed end includes a copper precursor feed port, a reducing agent feed port, and a tangential feed port, which is connected to the remaining part of the discharge port;

[0010] The aforementioned reactor also includes an air inlet, and a gas distributor is installed inside the reactor, which is connected to the air inlet of the reactor.

[0011] In some embodiments, the computer is connected to the particle size analyzer and controls the opening and closing of the discharge port via the solenoid valve.

[0012] In some embodiments, the nominal diameter of the aforementioned partial discharge port is larger than the nominal diameter of the aforementioned remaining partial discharge ports.

[0013] In some embodiments, the nominal diameter of the aforementioned discharge ports is DN80 to DN100;

[0014] The nominal diameter of the remaining discharge ports is DN50 to DN80.

[0015] In some embodiments, the above-mentioned reactor includes a cylindrical vessel body and a conical vessel body, wherein the conical vessel body is connected to the cylindrical vessel body;

[0016] The aforementioned feed end is located on the aforementioned cylindrical vessel body;

[0017] The discharge end is located on the aforementioned conical reactor body;

[0018] The aforementioned reactor is a jacketed reactor body, which is connected to a temperature controller and a pressure controller.

[0019] In some embodiments, the gas distributor is fixedly connected to the inner wall of the reactor, and the central axis of the gas distributor is parallel to the central axis of the reactor.

[0020] In some embodiments, the gas distributor includes an inlet pipe, one end of which is connected to the gas inlet of the reactor, and the other end of which is connected to a gas distribution pipe, which is connected to a plurality of branch pipes arranged at intervals.

[0021] In some embodiments, a gas flow controller is provided between the gas distributor’s inlet pipe and the reactor’s inlet.

[0022] In some embodiments, the copper precursor inlet and the reducing agent inlet are each independently connected to a conveying pipe, which is fixedly installed on the inner side wall of the reactor, and the outlet end of the conveying pipe is connected to a nozzle, which faces the center of the reactor.

[0023] In some embodiments, the copper precursor inlet and the reducing agent inlet are each independently connected to a high-pressure pump;

[0024] A booster pump is installed between the aforementioned tangential feed inlet and the aforementioned remaining discharge outlet.

[0025] The beneficial technical effects of this application are as follows:

[0026] 1. The ultrafine copper powder preparation device provided in this application is convenient for preparing copper powder with narrow particle size distribution, such as copper powder with Dv50 = 1μm ~ 10μm and Span value ≤ 0.8;

[0027] 2. The ultrafine copper powder preparation device provided in this application has low unit energy consumption.

[0028] 3. The ultrafine copper powder preparation device provided in this application facilitates the continuous industrial production of copper powder. Attached Figure Description

[0029] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0030] Figure 1 This is a schematic diagram of a device for preparing ultrafine copper powder according to some embodiments of this application;

[0031] Figure 2 This is another schematic diagram of the apparatus for preparing ultrafine copper powder according to some embodiments of this application;

[0032] Figure 3 This is another schematic diagram of the apparatus for preparing ultrafine copper powder according to some embodiments of this application;

[0033] Figure 4 This is a schematic diagram of the gas distributor of this application;

[0034] Figure 5 Scanning electron microscope image of copper powder prepared for a specific embodiment of this application.

[0035] The labels in the attached diagram are as follows:

[0036] 1000. Preparation apparatus;

[0037] 100. Reactor; 100a. Cylindrical vessel; 100b. Conical vessel;

[0038] 110. Copper precursor inlet; 110a. First high-pressure pump; 110b. Copper precursor conveying pipe; 110c. Copper precursor nozzle;

[0039] 120, reducing agent inlet; 120a, second high-pressure pump; 120b, reducing agent delivery pipe; 120c, reducing agent nozzle;

[0040] 130, air inlet; 130a, gas flow controller;

[0041] 140. Gas distributor; 1401. Inlet pipe; 1402. Gas distribution pipe; 140a. Branch pipe;

[0042] 150, First discharge port; 150a, Solenoid valve;

[0043] 160, Second discharge port; 160a, Booster pump;

[0044] 170. Tangential feed inlet;

[0045] 200. Particle size analyzer;

[0046] 300. Computer;

[0047] 400. Temperature controller;

[0048] 500. Pressure controller. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described below with reference to the accompanying drawings and specific embodiments. The embodiments in this application can be implemented in many different forms. Those skilled in the art will readily understand that the implementation methods and content can be transformed into various forms without departing from the spirit and scope of this application. Therefore, this application should not be construed as being limited only to the content described in the following embodiments. Without conflict, the embodiments and features in the embodiments of this application can be arbitrarily combined with each other.

[0050] In the description of this application, ordinal numbers such as "first" and "second" are used to avoid confusion of constituent elements, rather than to limit the quantity.

[0051] In this specification, for convenience, terms such as "middle," "upper," "lower," "front," "rear," "vertical," "horizontal," "top," "bottom," "inner," and "outer" are used to indicate orientation or positional relationships in conjunction with the accompanying drawings. This is solely for the purpose of describing this specification and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this application. The positional relationships of the constituent elements may be appropriately changed depending on the direction in which each constituent element is described. Therefore, the terminology used is not limited to those described in the specification and may be appropriately replaced as appropriate.

[0052] In this specification, unless otherwise expressly specified and limited, the terms "setup" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; a mechanical connection or an electrical connection; a direct connection, an indirect connection via an intermediate component, or a connection within two components. Those skilled in the art will understand the specific meaning of these terms in this application based on the specific circumstances.

[0053] "A and / or B" includes the following two combinations: A only, B only, and a combination of A and B.

[0054] "At least one of A, B and C" has the same meaning as "at least one of A, B or C", both including the following combinations of A, B and C: only A, only B, only C, combinations of A and B, combinations of A and C, combinations of B and C, and combinations of A, B and C.

[0055] Ultrafine copper powder is a nanomaterial with good conductivity and high strength, and is a key component of low-temperature conductive pastes for photovoltaics. Its particle size uniformity and surface oxygen content directly affect the paste's conductivity, printability, and low-temperature sintering performance. Studies have shown that when the copper powder particle size is monodisperse (Span < 0.8) and the surface oxygen content is below 0.3 wt%, the contact resistance of the low-temperature paste for heterojunction cells can be significantly reduced, while the sintering temperature can be controlled below 200℃, thereby improving cell conversion efficiency and reducing energy consumption.

[0056] Currently, the main methods for preparing ultrafine copper powder in China include traditional methods such as gas condensation, electrolysis, atomization, liquid-phase reduction, and hydrogen reduction. These methods lack a dynamic classification mechanism during the reaction process and cannot effectively control the uniformity of copper powder particles.

[0057] For example, while liquid-phase chemical reduction can prepare nano-copper powder, the lack of a dynamic classification mechanism during the reaction process leads to secondary agglomeration of particles with a wide particle size distribution (Span>1.2), requiring post-processing steps such as centrifugation and sieving. This not only increases production costs but also easily introduces impurities. Furthermore, the turbulence effect of conventional stirred reactors exacerbates copper powder oxidation, resulting in an oxygen content in the product generally exceeding 0.8 wt%. Similarly, while physical atomization can achieve continuous production, it relies on high-pressure atomization of 15–20 MPa, resulting in high energy consumption per unit area. Moreover, precise control of particle morphology during atomization is difficult, and a wide particle size distribution (Dv90 / Dv10>4) easily causes slurry sedimentation and stratification, affecting consistency. Therefore, neither chemical nor physical methods can ideally control particle size. To address these issues, this application provides an apparatus for preparing ultrafine copper powder. The preparation apparatus includes a reactor, a particle size analyzer, and a computer. The reactor includes a feed end and a discharge end. The discharge end includes multiple discharge ports arranged at intervals. The particle size analyzer is connected to some of the discharge ports, and some of the discharge ports are connected to one end of a solenoid valve. The other end of the solenoid valve is connected to the computer. The feed end includes a copper precursor feed port, a reducing agent feed port, and a tangential feed port. The tangential feed port is connected to the remaining discharge ports. The reactor also includes a gas inlet. A gas distributor is installed inside the reactor and is connected to the gas inlet of the reactor.

[0058] The apparatus provided in this application is suitable for the continuous industrial production of copper powder with a narrow particle size distribution, wherein the copper powder has a Dv50 of 1 μm to 10 μm, a Span value of ≤0.8, and a tap density of ≥4.0 g / cm³. 3 Oxygen content ≤ 0.3%.

[0059] The first aspect of this application is to provide an apparatus for preparing ultrafine copper powder, the apparatus comprising:

[0060] The reactor includes a feed end and a discharge end; the discharge end includes multiple discharge ports arranged at intervals.

[0061] Particle size analyzer: connecting part of the discharge port;

[0062] The aforementioned discharge port is connected to one end of a solenoid valve, and the other end of the solenoid valve is connected to a computer.

[0063] The aforementioned feed end includes a copper precursor feed port, a reducing agent feed port, and a tangential feed port, which is connected to the remaining part of the discharge port;

[0064] The aforementioned reactor also includes an air inlet, and a gas distributor is installed inside the reactor, which is connected to the air inlet of the reactor.

[0065] The reactor described in this application refers to a container used to react a copper precursor with a reducing agent to produce copper powder. The container can be made of carbon manganese steel, stainless steel, zirconium, nickel-based alloys (Hastelloy, Monel), or other composite materials. This application primarily uses 316L stainless steel. The inner wall of the reactor is coated with polytetrafluoroethylene (PTFE) for corrosion protection, and the effective volume can be 300L to 1000L. The shape of the reactor can be any shape conventional in the art, which will be described in detail in subsequent embodiments with reference to the accompanying drawings.

[0066] The particle size analyzer described in this application is an instrument used to measure and study the particle size of materials. In these embodiments, it refers to a laser diffraction detector, which includes any model conventional in the art. The laser diffraction detector used in these embodiments has a measurement range of 0.1 μm to 200 μm and a sampling frequency of ≥10 Hz.

[0067] The gas distributor of this application is a device for uniformly distributing gas across a cross-section. The structure of the gas distributor used in this application will be described in detail later, and will not be repeated here.

[0068] The solenoid valve of this application is a control element for controlling fluid flow. Specifically, the solenoid valve is connected to a discharge port and is used to control the opening and closing degree of these discharge ports.

[0069] The tangential feed inlet of this application refers to feeding tangentially along the wall of the reactor. This tangential feed inlet helps to reduce the impact of the circulating fine particulate material on the reactants inside the reactor and facilitates the distribution of the feed.

[0070] In this application, the copper precursor and reducing agent react in the reactor of the aforementioned preparation apparatus. After copper ions nucleate, they sink along the reactor wall and separate into coarse and fine particles with different particle sizes. The coarse particles flow into a portion of the outlet connected to a solenoid valve and are detected by a particle size analyzer. Coarse particles meeting the particle size requirements flow out from the partial outlet, while those not meeting the requirements are retained in the reactor to continue growth. Fine particles flow out from the remaining partial outlet and then re-enter the reactor through the tangential feed inlet to continue growth, repeating the above process. Therefore, the apparatus provided in this application is suitable for the continuous industrial production of copper powder with a narrow particle size distribution, characterized by a Dv50 of 1 μm to 10 μm, a Span value ≤ 0.8, and a tap density ≥ 4.0 g / cm³. 3 Oxygen content ≤ 0.3%.

[0071] In some embodiments, the computer is connected to the particle size analyzer and controls the opening and closing of the partial discharge port via the solenoid valve.

[0072] The particle size analyzer of this application is used to detect the particle size of coarse particles flowing out from the aforementioned partial discharge port in real time, and transmits the collected particle size data to a computer. The computer has a model built in it, which includes a dynamic response model between the particle size of copper powder, such as Dv10, Dv50, Dv90, etc., and the degree of opening and closing of the partial discharge port controlled by the solenoid valve. For example, this application discloses in these embodiments that when the Dv50 value of copper powder particle size exceeds a set threshold (such as 5±0.5μm), the system completes the valve opening compensation adjustment within 0.5s through a feedforward-feedback composite control strategy. The adjustment range changes gradually according to an exponential decay curve to avoid particle size oscillation caused by sudden changes in flow rate.

[0073] In some embodiments, the nominal diameter of the aforementioned partial discharge port is larger than the nominal diameter of the aforementioned remaining partial discharge port.

[0074] The aforementioned discharge ports of this application are designed to facilitate the discharge of copper powder particles with relatively larger particle sizes, such as coarse particles, while the remaining discharge ports are designed to facilitate the discharge of copper powder particles with relatively smaller particle sizes, such as fine particles. Therefore, this application defines the nominal diameter of each discharge port. The nominal diameter of this application is also known as the average outer diameter, which generally refers to the average value of the outer diameter and inner diameter of the pipe. The measurement method includes any measurement method conventional in the art.

[0075] In some embodiments, the nominal diameter of the above-mentioned discharge port is DN80 to DN100;

[0076] The nominal diameter of the remaining discharge ports is DN50 to DN80.

[0077] The material of the pipe corresponding to the discharge port of this application includes conventional materials in the field, such as galvanized or non-galvanized pipes. The nominal diameter of this application is represented by "DN", and the number following it represents the specific size. Generally speaking, the larger the number, the larger the nominal diameter.

[0078] In some embodiments, the above-mentioned reactor includes a cylindrical vessel body and a conical vessel body, wherein the conical vessel body is connected to the cylindrical vessel body;

[0079] The aforementioned feed end is located on the aforementioned cylindrical vessel body;

[0080] The aforementioned discharge end is located on the aforementioned conical vessel body;

[0081] The aforementioned reactor is a jacketed reactor body, which is connected to a temperature controller and a pressure controller.

[0082] The cylindrical reactor body of this application facilitates feeding, while the conical reactor body facilitates discharging. The cylindrical reactor body is also equipped with a tangential feed port to facilitate the formation of a spiral field to enhance particle classification. The classified coarse particles settle into the conical reactor body and are detected by a particle size analyzer at some of the discharge ports. The classified fine particles are further enriched along the axis of the reactor body and discharged through the remaining discharge ports of the conical reactor body. They then re-enter the reactor body through the tangential feed port on the cylindrical reactor body to undergo nucleation, enrichment, classification, and separation, thus repeating the above process.

[0083] The reaction between the copper precursor and the reducing agent in the reactor of this application needs to be completed under certain conditions, such as a certain temperature and pressure. Therefore, the reactor of this application is a jacketed reactor body, which is connected to a temperature controller and a pressure controller.

[0084] This application discloses temperature controllers and pressure controllers in these embodiments. These controllers generally include sensors (such as PT100 temperature sensors or piezoresistive pressure sensors), controllers, and actuators. The sensors are used to detect temperature and pressure values ​​and convert them into electrical signals. The controller is responsible for receiving the signals sent by the sensors and controlling the operation of the actuators accordingly to keep the temperature and pressure stable. The actuators are usually devices such as heaters, coolers, or gas flow controllers, which execute the instructions issued by the controller.

[0085] The temperature controller of this application is used to control and maintain the temperature inside the reactor to a certain level. Similarly, the humidity controller of this application is used to control and maintain the humidity inside the reactor to a certain level. In these embodiments, this application discloses that the temperature inside the reactor is 50℃~120℃ and the pressure is 0.6MPa~1.2MPa.

[0086] In these embodiments, this application discloses that the inner diameter of the cylindrical vessel is 800mm to 1200mm and the cone angle of the conical vessel is 55° to 65°.

[0087] In some embodiments, the gas distributor is fixedly connected to the inner wall of the reactor, and the central axis of the gas distributor is parallel to the central axis of the reactor.

[0088] The gas distributor of this application facilitates the uniform distribution of gas entering the reactor from the inlet across the cross-section. Therefore, in these embodiments, this application further selects the central axis of the gas distributor to be parallel to the central axis of the reactor.

[0089] In some embodiments, the gas distributor includes an inlet pipe, one end of which is connected to the inlet of the reactor, and the other end of which is connected to a gas distribution pipe, which connects to a plurality of branch pipes arranged at intervals. Gas entering from the inlet is distributed into each branch pipe via the gas distribution pipe, thereby achieving the technical objective of uniform gas distribution across the cross-section.

[0090] In these embodiments, this application discloses that the distance between each branch pipe is 40mm to 60mm, and the inner diameter of each branch pipe is 1mm to 3mm.

[0091] Based on the reaction conditions for producing copper powder from the reaction of copper precursor and reducing agent, this application selects an inert gas as the gas introduced, thereby facilitating the maintenance of a low oxygen content in the reactor, such as an oxygen content of less than or equal to 50 ppm.

[0092] In some embodiments, a gas flow controller is provided between the gas distributor’s inlet pipe and the reactor’s inlet.

[0093] The gas flow controller of this application is linked with the aforementioned pressure controller, and is used to control the partial pressure on the gas distributor and to maintain the pressure inside the reactor.

[0094] In some embodiments, the copper precursor inlet and the reducing agent inlet are each independently connected to a conveying pipe, which is fixedly disposed on the inner side wall of the reactor, and the outlet end of the conveying pipe is connected to a nozzle, which faces the center of the reactor.

[0095] The center of the reactor in this application is more likely to form a vortex field than the side wall. Therefore, adding the reactants to the center of the reactor makes it easier for the materials to mix and for the nucleation reaction to proceed rapidly.

[0096] In some embodiments, the copper precursor inlet and the reducing agent inlet are each independently connected to a high-pressure pump;

[0097] A diaphragm pump or a screw pump is installed between the aforementioned tangential feed inlet and the aforementioned remaining discharge outlet.

[0098] This application employs a high-pressure pump to inject a copper precursor and a reducing agent into the reactor. The copper precursor in this application includes any type conventional in the art, such as one or more of copper nitrate and copper acetate. Similarly, the reducing agent includes any type conventional in the art, such as formaldehyde, ascorbic acid, hydrazine hydrate, sodium hypophosphite, ascorbic acid, potassium tartrate, glucose, etc.

[0099] This application employs a diaphragm pump or screw pump to pressurize fine particles to 0.8 MPa–1.5 MPa, then circulates them back into the reactor through the tangential feed inlet. The material flow rate at the tangential feed inlet is controlled at 8 m / s–12 m / s. After further nucleation and growth, fine particles with a diameter ≤2 μm aggregate towards the central axis region of the reactor under the influence of the wall effect, while coarse particles ≥5 μm settle against the reactor wall under centrifugal force and flow to part of the discharge outlet. This design can further increase the contact probability between reactants, for example, by 27%–35%, while reducing the residual amount of fine particles in the cone bottom region, for example, the residual rate is <0.8%.

[0100] This application is in Figure 1 The diagram illustrates an apparatus for preparing ultrafine copper powder. The apparatus 1000 includes a reaction vessel 100, a particle size analyzer 200, and a computer 300. The reaction vessel 100 is a reaction tank, with its top end as the feed end and its bottom end as the discharge end. The discharge end includes multiple discharge ports arranged at intervals. This application... Figure 1 The diagram illustrates a first discharge port 150 and a second discharge port 160. A particle size analyzer 200 is connected to the first discharge port 150. The first discharge port 150 is also connected to one end of a solenoid valve 150a. The other end of the solenoid valve 150a is connected to a computer 300. The computer 300 is connected to the particle size analyzer 200 and controls the opening and closing degree of the first discharge port 150 through the solenoid valve 150a. Figure 1 It is also known that the feed end includes a copper precursor feed port 110, a reducing agent feed port 120 and a tangential feed port 170, the tangential feed port 170 being connected to the second discharge port 160; and a booster pump 160a is provided between the tangential feed port 170 and the second discharge port 160, the booster pump being a diaphragm pump or a screw pump.

[0101] The aforementioned reactor 100 also includes an air inlet 130. A gas distributor 140 is provided inside the reactor 100. The gas distributor 140 is connected to the air inlet 130 of the reactor 100. A gas flow controller 130a is provided between the air inlet pipe 1401 of the gas distributor 140 and the air inlet 130 of the reactor 100.

[0102] Combination Figure 2 It can be seen that... Figure 2This illustration shows another apparatus 1000 for preparing ultrafine copper powder. The reactor 100 of this apparatus includes a cylindrical reactor 100a and a conical reactor 100b, wherein the conical reactor 100b is connected to the cylindrical reactor 100a. The feed end is located on the cylindrical reactor 100a, and the discharge end is located on the conical reactor 100b. The cylindrical reactor of this application facilitates feeding, and the conical reactor facilitates multi-stage screening of copper powder particles to obtain copper powder with a narrow particle size distribution.

[0103] Combination Figure 3 It can be seen that... Figure 3 An alternative apparatus 1000 for preparing ultrafine copper powder is illustrated. In this apparatus 1000, the copper precursor inlet 110 and the reducing agent inlet 120 in the reactor 100 are independently connected to copper precursor delivery pipes 110b and reducing agent delivery pipes 120b, respectively. The copper precursor delivery pipes 110b and reducing agent delivery pipes 120b are fixedly disposed on the inner wall of the reactor 100. The outlet ends of the copper precursor delivery pipes 110b and reducing agent delivery pipes 120b are respectively connected to copper precursor nozzles 110c and reducing agent nozzles 120c, which face the center of the reactor 100. This design facilitates the mixing of reactants and rapid nucleation reactions.

[0104] Meanwhile, the copper precursor inlet 110 and the reducing agent inlet 120 are each independently connected to the first high-pressure pump 110a and the second high-pressure pump 120a to facilitate the injection of reaction materials into the reactor 100.

[0105] This application is in Figure 4 The diagram also illustrates the structure of a gas distributor 140, which includes an inlet pipe 1401. One end of the inlet pipe 1401 is connected to the inlet port 130 of the aforementioned reaction vessel 100, and the other end is connected to a gas distribution pipe 1402. The gas distribution pipe 1402 is connected to a plurality of branch pipes 140a arranged at intervals. Gas entering from the inlet port 130 is distributed through the gas distribution pipe 1402 into each branch pipe 140a, thereby achieving the technical objective of uniform gas distribution across the cross-section.

[0106] Example 1

[0107] A method using the above-mentioned Figure 2The schematic diagram illustrates the preparation process of ultrafine copper powder using the preparation apparatus 1000. Specifically, the reactor 100 is a 500L 316L stainless steel reactor, with its main structure consisting of a top cylindrical body (1000mm in diameter and 1200mm in height) and a conical body (60° cone angle and 600mm in height). Two plunger-type high-pressure dosing pumps (flow accuracy ±0.5%) inject copper nitrate solution (1.2mol / L) and ascorbic acid reducing agent (0.8mol / L) at 60℃ at gradient rates of 2L / min and 1.5L / min, respectively. A gas distributor maintains a pressure of 0.8MPa and an oxygen content of <50ppm inside the reactor. Three sets of PT100 temperature sensors and piezoresistive pressure sensors monitor the reaction environment in real time and are interlocked with the jacketed steam heating system and safety relief valve for control. The conical bottom is equipped with a two-stage discharge system: the first coarse particle outlet (DN80) is connected to a Malvern Insitec S3 online particle size analyzer via a solenoid valve (stroke time 0.5s / 90°), and the second fine particle outlet (DN50) is connected to a pneumatic diaphragm pump (flow rate 3m³ / h). 3 The material is returned to the top circulation feed inlet at a tangential flow rate of 10 m / s (at a pressure of 1.2 MPa) to enrich fine particles with a particle size of Dv50≤2μm at the center of the reactor and allow coarse particles with a particle size of Dv50≥5μm to settle at the bottom of the conical reactor.

[0108] During operation, the reactants undergo liquid-phase reduction at 85℃ for 30 minutes before entering the dynamic classification stage. The initial coarse particle outlet opening is set to 60%. The online particle size analyzer provides real-time feedback of the Dv50 value to the fuzzy PID controller. When a particle size deviation from the 5.0±0.5μm threshold is detected, the system adjusts with a response time of 0.5s. If coarse particles exceed the limit, the valve opens by 5% every 0.5s; if fine particles are excessive, a step-wise throttling method is used (reducing the opening by 3% at each stage). The circulation flow ratio is stabilized at 4:1 (fine particle circulation volume 3m³ / min). 3 / h, coarse particle output 0.75m 3 After running continuously for 2 hours, the system automatically switched to steady-state mode, ultimately obtaining spherical copper powder with a Dv50 value of 4.9–5.1 μm and a Span value of 0.8. The tap density of this spherical copper powder was 5.2 g / cm³. 3 The oxygen content is <0.3%. The scanning electron microscope image of this copper powder is shown below. Figure 5 Indication, combined Figure 5 It can be seen that the copper powder prepared in this embodiment has a uniform particle size distribution.

[0109] Further calculations show that the unit energy consumption of the above-mentioned preparation device is 1.2 kWh / kg, which is 24% lower than that of the traditional process, and the single-reactor volume utilization rate reaches 93%.

[0110] In summary, the apparatus provided in this application is suitable for the continuous industrial production of high-purity copper powder with narrow particle size distribution for conductive pastes.

[0111] It should be understood that the terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “described” as used herein may also include the plural forms. The terms “comprising,” “including,” “containing,” and “having” are inclusive and therefore indicate the presence of the stated features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein are not construed as requiring them to be performed in a particular order described or illustrated unless the order of performance is explicitly indicated. It should also be understood that additional or alternative steps may be used.

[0112] The above description is merely a preferred embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. An apparatus for preparing ultrafine copper powder, characterized in that: The application relates to a reaction kettle and a particle size analyzer. The reaction kettle comprises a feeding end and a discharging end; the discharging end comprises a plurality of discharging ports arranged at intervals; The particle size analyzer is connected with part of the discharging ports; One end of an electromagnetic valve is connected with the part of the discharging ports, and the other end of the electromagnetic valve is connected with a computer; The feeding end comprises a copper precursor feeding port, a reducing agent feeding port and a tangential feeding port, and the tangential feeding port is connected with the rest of the discharging ports; The reaction kettle further comprises a gas inlet, and a gas distributor is arranged in the reaction kettle and connected with the gas inlet of the reaction kettle.

2. The preparation device according to claim 1, characterized in that: The computer is connected with the particle size analyzer, and the opening and closing degrees of the part of the discharging ports are controlled through the electromagnetic valve.

3. The preparation device according to any one of claims 1 to 2, characterized in that: The nominal diameter of the part of the discharging ports is larger than that of the rest of the discharging ports.

4. The preparation device according to claim 3, characterized in that: The nominal diameter of the part of the discharging ports is DN80-DN100; The nominal diameter of the rest of the discharging ports is DN50-DN80.

5. The preparation device according to any one of claims 1 to 2, characterized in that: The reaction kettle comprises a cylindrical kettle body and a conical kettle body, and the conical kettle body is connected with the cylindrical kettle body; The feeding end is arranged on the cylindrical kettle body; The discharging end is arranged on the conical kettle body; The reaction kettle is a jacketed kettle body, and the jacketed kettle body is connected with a temperature controller and a pressure controller.

6. The preparation device according to any one of claims 1 to 2, characterized in that: The gas distributor is fixedly connected with the inner side wall of the reaction kettle, and the central axis of the gas distributor is parallel to the central axis of the reaction kettle.

7. The preparation device according to claim 6, characterized in that: The gas distributor comprises a gas inlet pipe, one end of the gas inlet pipe is connected with the gas inlet of the reaction kettle, the other end of the gas inlet pipe is connected with a gas distribution pipe, and the gas distribution pipe is connected with a plurality of branch pipes arranged at intervals.

8. The preparation device according to claim 7, characterized in that: A gas flow controller is arranged between the gas inlet pipe of the gas distributor and the gas inlet of the reaction kettle.

9. The preparation device according to any one of claims 1 to 2, characterized in that: The copper precursor feeding port and the reducing agent feeding port are respectively and independently connected with feeding pipes, the feeding pipes are fixedly arranged on the inner side wall of the reaction kettle, and the discharging end of the feeding pipes is connected with a nozzle, and the nozzle faces the center of the reaction kettle.

10. The preparation device according to any one of claims 1 to 2, characterized in that: The copper precursor feeding port and the reducing agent feeding port are respectively and independently connected with high-pressure pumps. A booster pump is arranged between the tangential feeding port and the rest of the discharging ports.

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