Multi-stage grinding system for preparing high-purity zinc powder

Abstract

The invention relates to the technical field of zinc powder processing equipment, in particular to a multi-stage grinding system for preparing high-purity zinc powder, which comprises a primary grinding unit, a secondary grinding unit, a tertiary fine grinding unit, a separating and screening unit, a collecting unit, a cooling system and a control system, crushing larger zinc particles into a preset coarse particle size; and the secondary grinding unit is a ball mill and is used for further grinding the zinc powder subjected to primary grinding to ensure that particles reach a medium particle size range. According to the multi-stage grinding system, through automation, multi-stage smashing and real-time feedback control, efficient production of zinc powder is achieved, and it is guaranteed that the particle size of the zinc powder is uniform, and the purity of the zinc powder is high. A system integrated cooling mechanism prevents oxidation, a separation screening unit improves screening efficiency, and a sealed conveying device ensures environmental protection and safety. Overall automation improves production efficiency and is suitable for large-scale industrial application.

Description

Technical Field

[0001] The invention relates to the technical field of zinc powder processing equipment, and in particular to a multi-stage grinding system for preparing high-purity zinc powder. Background Art

[0002] As an important metal material, zinc powder is widely used in chemical industry, metallurgy, electronics, coatings and other fields. High-purity and uniform-particle-size zinc powder plays a key role in certain high-end application scenarios, such as battery manufacturing, zinc-based alloys, corrosion-resistant coatings and catalysts. The zinc powder preparation processes in related technologies mainly include mechanical grinding, vapor deposition and electrolysis. Among them, mechanical grinding is widely used, and zinc ingots are usually ground by equipment such as ball mills or hammer mills. However, this method often has problems such as uneven grinding and unstable particle distribution, which makes it difficult to accurately control the particle size and purity of the final product. At the same time, due to the high temperature during mechanical grinding, zinc powder is easily oxidized during the grinding process, thereby reducing the purity of the product. In addition, grinding equipment usually lacks precise monitoring and feedback mechanisms, and cannot adjust the particle size and grinding parameters in real time, further affecting product quality. In view of this, it is necessary to improve the current zinc powder grinding system to solve the above problems;

[0003] The above information disclosed in this Background section is only for understanding the background of the present inventive concept and therefore it may contain information that does not constitute prior art. Summary of the invention

[0004] The object of the present invention is to provide a multi-stage grinding system for preparing high-purity zinc powder, so as to solve the problem that the zinc powder preparation process proposed in the above-mentioned background technology mainly includes mechanical grinding method, vapor deposition method and electrolysis method. Among them, the mechanical grinding method is widely used, and the zinc ingot is usually ground by equipment such as a ball mill or a hammer mill, but this method often has problems such as uneven grinding and unstable particle distribution, which makes it difficult to accurately control the particle size and purity of the final product. At the same time, due to the high temperature during the mechanical grinding process, the zinc powder is easily oxidized during the grinding process, thereby reducing the purity of the product. In addition, the grinding equipment usually lacks an accurate monitoring and feedback mechanism, and cannot adjust the particle size and grinding parameters in real time, further affecting the problem of product quality.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A multi-stage grinding system for preparing high-purity zinc powder comprises a primary grinding unit, a secondary grinding unit, a tertiary fine grinding unit, a separation and screening unit, a collection unit, a cooling system and a control system, wherein the primary grinding unit is a hammer mill for coarsely grinding zinc ingots and grinding larger zinc particles to a preset coarse particle size; the secondary grinding unit is a ball mill for further grinding the zinc powder after primary grinding to ensure that the particles reach a medium particle size range; the tertiary fine grinding unit is an air flow mill for ultrafinely grinding the zinc powder through high-speed airflow to achieve a particle size of micrometer or even nanometer level; the separation and screening unit performs fine classification through a vibrating screen according to the particle size of the ground zinc powder, and the screened material is returned to the secondary or tertiary grinding unit for further grinding, and the screened material enters the collection unit; the cooling system is used to control the high temperature generated during the grinding process to prevent the zinc powder from oxidizing at high temperature and maintain high purity.

[0007] The control system includes a PLC and multiple sensors, which automatically adjust the working parameters of each unit by real-time monitoring of grinding temperature, pressure, material flow and screening effect, and optimize the grinding efficiency through a closed-loop control algorithm. The control system operates based on a multi-stage grinding optimization model to control the particle size distribution and efficiency of each grinding unit. The model formula is as follows:

[0008]

[0009] Where D(t) is the particle size distribution at the final grinding time t, D 0 , D 1 , …, D n are the initial particle sizes of each level of grinding, λ 1 ,λ 2 , …, λ n is the grinding rate constant at each level, t 1 , t 2 ,…,t n is the grinding time for each grinding level.

[0010] In addition, the collection unit is equipped with a real-time particle size analyzer, which can perform online detection of the collected zinc powder and analyze its particle size distribution and purity. The system adjusts the front-end grinding parameters based on the analysis results to ensure that the prepared zinc powder meets the high purity requirements.

[0011] The particle size analyzer measures the particle size distribution of zinc powder in real time by light scattering or laser diffraction, and calculates the particle size distribution function:

[0012]

[0013] Where D(v, t) is the particle size distribution function, v i is the particle size, N is the number of samples, and t is the distribution characteristic value of the particle size;

[0014] The system counts the obtained particle size distribution and generates the cumulative percentage content Q of a specific particle size range. 3 (x). Its calculation formula is:

[0015]

[0016] Among them, Q 3 (x) represents the percentage of zinc powder with a particle size less than or equal to x in the total zinc powder, and f(D) is the probability density function of the zinc powder particle size. When the real-time detected zinc powder particle size distribution deviates from the target value, the control system adjusts the working parameters of the front-end grinding unit through the following feedback control algorithm:

[0017]

[0018] Among them, ΔP is the parameter adjustment of the grinding unit, D target is the target particle size, D measured is the actual detected particle size, K p , K i , K d They are the coefficients of the proportional, integral and differential controllers, respectively, which are used to adjust parameters such as grinding speed, pressure and time for large to precise control.

[0019] As a preferred technical solution, the air flow velocity and pressure of the three-stage fine grinding unit are determined by the following formula:

[0020]

[0021] Among them, v is the air velocity, P is the pressure, and ρ is the gas density, which are used to control the working state of the air flow mill to achieve efficient crushing of iron powder.

[0022] As a preferred technical solution, the screening efficiency of the separation and screening unit is optimized and calculated by the following formula:

[0023]

[0024] Among them, "E" is the screening efficiency, "M below the sieve" is the mass of zinc powder passing through the sieve, and "M above the sieve" is the mass of zinc powder not passing through the sieve.

[0025] As a preferred technical solution, the screen is a multi-layer vibrating screen with three layers, which are used to screen zinc powder with different particle size ranges.

[0026] As a preferred technical solution, the cooling system adopts a circulating cooling water system combined with air flow cooling, and the temperature control during the cooling process adopts the following formula:

[0027] T 出 =T 进 -Q.Cp

[0028] Among them, T 出 is the temperature of zinc powder after cooling, T 进 is the temperature before cooling, Q is the cooling water flow rate, C p The specific heat capacity of water is measured by real-time monitoring of water temperature and flow rate to precisely control the cooling effect.

[0029] As a preferred technical solution, the airflow cooling part of the cooling system uses compressed air, and the air is introduced into the grinding chamber through a pipeline system. During the cooling process, direct contact between water and zinc powder is avoided to prevent the zinc powder from being oxidized.

[0030] As a preferred technical solution, the collection unit includes a sealed container with a negative pressure conveying device, which is used to collect and convey zinc powder that has been screened to meet the particle size requirements, prevent dust leakage and ensure the cleanliness of the production environment.

[0031] The beneficial effects of the present invention are:

[0032] Through this system, the multi-stage grinding system provided by the present invention realizes efficient production of zinc powder through automation, multi-stage crushing and real-time feedback control, ensuring uniform particle size and high purity. The system integrates a cooling mechanism to prevent oxidation, a separation and screening unit to improve screening efficiency, and a sealed conveying device to ensure environmental protection and safety. The overall automation improves production efficiency, is suitable for large-scale industrial applications, and can meet the demand for high-purity zinc powder in the high-end market. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a schematic diagram of the structure of a multi-stage grinding system for preparing high-purity zinc powder proposed by the present invention;

[0034] Figure 2 The present invention provides a workflow diagram of a multi-stage grinding system for preparing high-purity zinc powder. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0036] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0037] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0038] Reference Figure 1-2 , a multi-stage grinding system for preparing high-purity zinc powder, including a primary grinding unit, a secondary grinding unit, a tertiary fine grinding unit, a separation and screening unit, a collection unit, a cooling system and a control system. The primary grinding unit adopts a hammer mill, which is mainly used for preliminary crushing of zinc ingots or coarse zinc powder. The hammer mill uses a high-speed rotating hammer to impact and crush the zinc ingot, and the resulting particle size is about hundreds of microns to millimeters. In order to ensure the grinding effect, the primary grinding unit is equipped with a hammer speed adjustment device, which can automatically adjust the rotation speed of the hammer according to the nature of the input material.

[0039] In order to control the degree of particle crushing, the primary grinding unit is equipped with an online material detection device to monitor the particle size of the material in real time and output it to the control system for adjustment. The crushed coarse zinc powder enters the secondary grinding unit through the conveying device.

[0040] The secondary grinding unit uses a ball mill, which is mainly used to further grind the zinc powder after primary grinding to a finer particle size (about 20-50 microns). The ball mill further refines the zinc powder through the impact and grinding action of the grinding medium (such as steel balls). To ensure the uniformity of the particles, the operating parameters of the ball mill, such as speed and grinding time, are adjusted in real time by the control system.

[0041] After the secondary grinding, the particle size of the zinc powder has been significantly reduced and enters the next stage of fine grinding. During this process, the secondary grinding unit is connected to the cooling system to prevent the zinc powder from oxidizing due to the high temperature generated by grinding.

[0042] The third-stage grinding unit is a jet mill, which is responsible for further crushing the zinc powder from the second-stage grinding unit to micron or even nanometer level. The jet mill uses compressed air to impact and shear the zinc powder, controlling the particle size within the range of 1-10 microns.

[0043] The working principle of the air jet mill is to accelerate the zinc powder to an ultra-high speed through high-pressure air flow, and then use the high-speed collision between particles to achieve crushing. The flow rate and pressure of compressed air can be controlled by the following formula:

[0044]

[0045] Where v is the air velocity, P is the pressure inside the jet mill, and ρ is the air density. The control system is based on the operating status of the jet mill and the real-time particle size.

[0046] Detection results, dynamically adjust air flow speed and pressure.

[0047] In order to prevent the zinc powder from oxidizing due to the increase in temperature during the grinding process, the system integrates a cooling device. The cooling system includes a circulating cooling water system and an air flow cooling system:

[0048] The cooling water system is mainly used to reduce the heat generated by ball mills and hammer mills during the grinding process. The generated heat is taken away by the circulation of cooling water to keep the working temperature of the grinding unit within the set range. The temperature change control of the cooling water system is as follows:

[0049] T 出 =T 进 -Q.C p Among them, Tout is the temperature of the zinc powder after cooling, Tin is the temperature when entering the cooling system, Q is the water flow rate, C p is the specific heat capacity of water.

[0050] Airflow cooling system: For airflow mills, compressed air is used to cool the inside of the cavity to prevent direct contact between cooling water and zinc powder to prevent oxidation. The airflow cooling system introduces compressed air into the grinding chamber through a pipe, absorbing excess heat through high-speed airflow.

[0051] The separation and screening unit uses a multi-layer vibrating screen to separate the zinc powder by particle size through screens of different mesh sizes. The vibration frequency and amplitude of the vibrating screen are automatically adjusted by the control system to ensure screening efficiency. The oversize (zinc powder with larger particles) will be returned to the secondary or tertiary grinding unit for re-grinding, while the undersize (zinc powder that meets the particle size requirements) will enter the collection unit.

[0052] The screening efficiency is calculated by the following formula:

[0053]

[0054] Among them, "E" is the screening efficiency, "M below the sieve" is the mass of zinc powder passing through the sieve, and "M above the sieve" is the mass of zinc powder not passing through the sieve.

[0055] The screened zinc powder is collected by a sealed negative pressure conveying device and transported to a storage unit. The collection unit remains sealed to prevent the zinc powder from escaping and ensure the cleanliness of the production environment. The negative pressure conveying device transports the zinc powder to a designated location through a vacuum pump.

[0056] The system integrates a real-time particle size analyzer to detect the particle size of the zinc powder after screening online. The particle size distribution of the zinc powder is analyzed by laser diffraction or light scattering, and the particle size distribution function is calculated:

[0057]

[0058] Where D(v, t) is the particle size distribution function, v i is the particle size, N is the number of samples, and t is the distribution characteristic value of the particle size;

[0059] If the analysis results show that the zinc powder particle size is too large or too small, the system adjusts the working parameters of the grinding unit through the PID feedback control algorithm. The algorithm is as follows:

[0060]

[0061] Among them, ΔP is the parameter adjustment of the grinding unit, D target is the target particle size, D measured is the actual detected particle size.

[0062] The control system of the present invention adopts PLC (Programmable Logic Controller) for overall control, and dynamically adjusts the operating parameters of the primary, secondary and tertiary grinding units through real-time data collection and processing. The control system is used in conjunction with equipment such as a particle size analyzer and a temperature sensor to achieve automatic adjustment of grinding speed, grinding time and temperature control.

[0063] In this embodiment, the system can gradually crush the particle size of zinc powder from larger particles to micron or even nanometer level through the coordinated work of primary, secondary and tertiary fine grinding units. The optimized design of each stage of grinding equipment ensures the precise control of zinc powder with different particle sizes, avoids the problem of uneven particle size distribution of a single grinding equipment, and effectively improves the particle size uniformity and purity of the final product.

[0064] In order to solve the problem of zinc powder oxidation due to temperature rise during grinding, the system is specially designed with a cooling system that combines water cooling and air flow cooling. This system can keep the operating temperature of the equipment within a reasonable range during the grinding process, effectively avoiding the impact of high temperature on the quality of zinc powder and ensuring the high purity of zinc powder.

[0065] The multi-layer vibrating screen separation and screening unit in the system can perform efficient classification screening according to the particle size distribution of zinc powder. The screened material can be automatically returned to the grinding equipment for secondary grinding, avoiding material waste. The high screening efficiency can ensure the stability of the zinc powder particle size that meets the requirements, optimize the production process, and reduce unnecessary resource consumption.

[0066] The grinding system adopts an automated control system, which can automatically regulate the grinding process, reduce manual intervention, and improve production efficiency. In addition, the real-time monitoring system and feedback control greatly shorten the debugging and downtime of the equipment, ensure the continuity and stability of production, and are suitable for large-scale industrial production.

[0067] The multi-stage grinding system provided by the present invention realizes efficient production of zinc powder through automation, multi-stage crushing and real-time feedback control, ensuring uniform particle size and high purity. The system integrates a cooling mechanism to prevent oxidation, a separation and screening unit to improve screening efficiency, and a sealed conveying device to ensure environmental protection and safety. Overall automation improves production efficiency, is suitable for large-scale industrial applications, and can meet the demand for high-purity zinc powder in the high-end market.

[0068] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A multi-stage grinding system for preparing high-purity zinc powder, comprising a primary grinding unit, a secondary grinding unit, a tertiary fine grinding unit, a separation and screening unit, a collection unit, a cooling system and a control system, characterized in that: The primary grinding unit is a hammer mill, which is used to coarsely grind the zinc ingot and grind the larger zinc particles into a preset coarse particle size; the secondary grinding unit is a ball mill, which is used to further grind the zinc powder after primary grinding to ensure that the particles reach a medium particle size range; the tertiary fine grinding unit is an air flow mill, which uses high-speed airflow to ultra-finely grind the zinc powder to make the particle size reach micrometer level or even nanometer level; The separation and screening unit performs fine classification through a vibrating screen according to the particle size of the ground zinc powder, and the screened material returns to the secondary or tertiary grinding unit for further grinding, and the screened material enters the collection unit; the cooling system is used to control the high temperature generated during the grinding process, prevent the zinc powder from oxidizing at high temperature, and maintain high purity; The control system includes a PLC and multiple sensors, which automatically adjust the working parameters of each unit by real-time monitoring of grinding temperature, pressure, material flow and screening effect, and optimize the grinding efficiency through a closed-loop control algorithm. The control system operates based on a multi-stage grinding optimization model to control the particle size distribution and efficiency of each grinding unit. The model formula is as follows: Where D(t) is the particle size distribution at the final grinding time t, D0, D1, ..., D n are the initial particle sizes of each level of grinding, λ1, λ2, …, λ n are the grinding rate constants at each level, t1, t2, ..., t n is the grinding time for each grinding level; In addition, the collection unit is equipped with a real-time particle size analyzer, which can perform online detection of the collected zinc powder and analyze its particle size distribution and purity. The system adjusts the front-end grinding parameters based on the analysis results to ensure that the prepared zinc powder meets the high purity requirements; The particle size analyzer measures the particle size distribution of zinc powder in real time by light scattering or laser diffraction, and calculates the particle size distribution function: Where D(v, t) is the particle size distribution function, v i is the particle size, N is the number of samples, and t is the distribution characteristic value of the particle size; The system performs statistics on the obtained particle size distribution and generates the cumulative percentage content Q3(x) of a specific particle size range. The calculation formula is: Q3(x)=∫0 x f(D)dD Where Q3(x) represents the percentage of zinc powder with a particle size less than or equal to x in the total zinc powder, and f(D) is the probability density function of the zinc powder particle size. When the real-time detected zinc powder particle size distribution deviates from the target value, the control system adjusts the working parameters of the front-end grinding unit through the following feedback control algorithm: Among them, ΔP is the parameter adjustment of the grinding unit, D target is the target particle size, D measured is the actual detected particle size, K p , K i , K d They are the coefficients of the proportional, integral and differential controllers, respectively, which are used to adjust parameters such as grinding speed, pressure and time for large to precise control.

2. A multi-stage grinding system for preparing high-purity zinc powder according to claim 1, characterized in that: The air flow velocity and pressure of the three-stage fine grinding unit are determined by the following formula: Among them, v is the air velocity, P is the pressure, and ρ is the gas density, which are used to control the working state of the air flow mill to achieve efficient crushing of iron powder.

3. A multi-stage grinding system for preparing high-purity zinc powder according to claim 1, characterized in that: The screening efficiency of the separation and screening unit is optimized and calculated by the following formula: Among them, "E" is the screening efficiency, "M below the sieve" is the mass of zinc powder passing through the sieve, and "M above the sieve" is the mass of zinc powder not passing through the sieve.

4. A multi-stage grinding system for preparing high-purity zinc powder according to claim 3, characterized in that: The screen is a multi-layer vibrating screen with three layers, which are used to screen zinc powder with different particle size ranges.

5. A multi-stage grinding system for preparing high-purity zinc powder according to claim 1, characterized in that: The cooling system adopts a circulating cooling water system combined with air flow cooling, and the temperature control during the cooling process adopts the following formula: T 出 =T 进 -Q·C p Among them, T 出 is the temperature of zinc powder after cooling, T 进 is the temperature before cooling, Q is the cooling water flow rate, C p The specific heat capacity of water is measured by real-time monitoring of water temperature and flow rate to precisely control the cooling effect.

6. A multi-stage grinding system for preparing high-purity zinc powder according to claim 1, characterized in that: The airflow cooling part of the cooling system adopts compressed air, and introduces the air into the grinding chamber through the pipeline system. During the cooling process, direct contact between water and zinc powder is avoided to prevent the zinc powder from being oxidized.

7. A multi-stage grinding system for preparing high-purity zinc powder according to claim 1, characterized in that: The collecting unit comprises a sealed container with a negative pressure conveying device, which is used to collect and convey zinc powder that has been screened to meet the particle size requirements, prevent dust leakage and ensure the cleanliness of the production environment.

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