AU2020102102A4

AU2020102102A4 - Method and System for Drying Flux

Info

Publication number: AU2020102102A4
Application number: AU2020102102A
Authority: AU
Inventors: Tianran DING; Yanhong Fan; Yucan Fu; Guoqin HUANG; Limei JIN; Weimin LONG; Huawei SUN; Fenglin Zhang; Sujuan ZHONG
Original assignee: Zhengzhou Research Institute of Mechanical Engineering Co Ltd
Current assignee: Zhengzhou Research Institute of Mechanical Engineering Co Ltd
Priority date: 2020-01-13
Filing date: 2020-09-02
Publication date: 2020-10-08
Anticipated expiration: 2028-09-02
Also published as: CN111197925A; CN111197925B

Abstract

ONU20018948AU Abstract The present disclosure relates to the technical field of treatment of fluxes, and in particular to a method and system for drying a flux. The method for drying a flux includes steps of: drying a flux under the action of microwaves. The system for drying flux includes: a casing and a conveying unit passing through the casing. The casing includes a microwave drying chamber and a cooling chamber along a direction of conveyance by the conveying unit. A microwave generator is arranged in the microwave drying chamber. In the present disclosure, a flux is dried using microwaves by simple processes and is heated uniformly, so that the dried flux product has high quality and has a uniform color, and a uniform drying effect is achieved with less energy at high efficiency. 18 ONU20018948AU ONU20018948AU Drawings 32 4 212 FIG.I1 ONU20018948AU

Description

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Drawings

32 4

212

FIG.I1

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Method and System for Drying Flux

Cross-Reference to Related Applications This application claims priority of Chinese Patent Application No. 2020100308592, filed with the Chinese Patent Office on January 13, 2020, entitled "Method and System for Drying Flux", the contents of which are incorporated herein by reference in their entirety. Technical Field The present disclosure relates to the technical field of treatment of fluxes, and in particular to a method and system for drying a flux. Background Art Flux (or brazing flux) refers to a fluxing agent used in a brazing process, by which oxides on a surface of a base material and a brazing material can be removed so as to achieve a protective effect. It is necessary to dry the flux so as to remove moisture or the like from the flux before brazing, because high moisture content will adversely affect the welding. Currently, the flux is usually subjected to drying treatment by heating and drying the flux in a drying baker or drying the flux in a drying box, which involves high equipment cost and results in low working efficiency. Moreover, these methods for drying fluxes are carried out with a poor ventilation effect and with insufficient accuracy of temperature control. As a result, the dried flux has nonuniform particle sizes and uneven colors and thus shows substantially reduced performance. In view of this, the present disclosure is particularly proposed. Summary An object of the present disclosure is to provide a method for drying a flux to solve the technical problems existing in the prior art in which the flux is dried at low efficiency with poor uniformity. Another object of the present disclosure is to provide a system for drying flux, which has a simple structure, enables uniform drying of a flux, and has a high drying efficiency. In order to achieve the above objects of the present disclosure, the following technical solution is employed: A method for drying a flux includes a step of: drying a flux under the action of microwaves;

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optionally, the flux is selected from a powdered flux, a paste flux, and a granular flux. Microwave is a kind of electromagnetic wave whose band is between radio wave and infrared wave, which has a wavelength ranging from 1 mm to 1 m and a frequency ranging from 300 MHz to 300 GHz. The microwave is also called as ultra-high-frequency electromagnetic wave because of its high frequency. In the present disclosure, a flux is dried by using microwaves. Heating a flux by microwaves means a heating mode in which the interior of the body of the flux is heated by dielectric loss in the electromagnetic field, and microwave energy is absorbed by the flux and converted into heat energy so that the flux heats up simultaneously as a whole. In this way, the inside and outside of an object are simultaneously heated and its temperature is raised without need of any heat conduction process, and the object is heated uniformly at a rapid rate. The heating purpose can be achieved within a period of time which is only a fraction or several tenths of that in the traditional heating mode. Compared with the traditional flux drying mode, the drying treatment of the flux by using microwaves have advantages such as providing a high temperature-raising rate, uniform heating, strong controllability, selective heating, sensitive response, strong penetrating power, cleanliness, and no pollution. The composition of the flux contains metal. Microwaves irradiated onto the surface of metal will be totally reflected and will not work on the metal. If microwaves act on non-metallic dielectrics, the microwaves will be absorbed and penetrated due to the characteristics of the dielectrics, thereby generating high-frequency electric and magnetic fields. The ability of a substance to absorb microwaves is determined mainly by its dielectric loss factor. Water molecules are polar molecules with a large dielectric constant and with a large dielectric loss factor and have a strong ability to absorb microwaves. Therefore, selective heating can be achieved and the drying efficiency can be improved. A method of drying a flux using microwaves is not dislosed in the prior art. Since the flux contains metal that does not absorb microwaves and tends to discharge electricity, the microwave equipment may be partially ignited. In the present disclosure, the temperature obtained under the action of microwaves is controlled so that the temperature is not higher than the ignition point of the flux. The problem can be avoided by adjusting, for example, the microwave power and the material drying time. In a specific embodiment of the present disclosure, the microwaves have a power of 10 to 20 kW, preferably 12 to 15 kW. For example, in different embodiments, the microwaves may have a power of 10 kW, 11 kW, 12 kW, 13 kW, 14 kW, 15 kW, 16 kW, 17 kW, 18 kW, 19 kW, kW, or the like.

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The temperature of the flux can be increased at a certain rate by using microwaves with power within the above range, thereby avoiding an excessively high temperature caused by excessively rapid heating and also avoiding a low-efficiency temperature caused by excessively slow heating. In a specific embodiment of the present disclosure, the drying includes: maintaining a temperature of the flux after it reaches 200 to 250 °C. After the temperature of the flux reaches the above range, moisture in the flux can be quickly removed. Both efficiency and energy consumption are taken into consideration here. In a specific embodiment of the present disclosure, the flux reaches a temperature of 200 to 250 °C after 6 to 15 min. The temperature of the flux is raised to a target temperature by using an appropriate heating rate in cooperation with the microwave power, thereby avoiding the burden or impact on the interior of the flux due to an excessively rapid temperature rise while avoiding the problem of low efficiency caused by an excessively slow temperature rise. In a specific embodiment of the present disclosure, the maintaining of temperature is performed for a period of 12 to 30 min. The microwaves have a power of 12 to 15 kW during the maintaining of temperature. In a specific embodiment of the present disclosure, the flux is spread in advance at a thickness of 1 to 2.5 cm before the drying. For example, in different embodiments, the flux may be spread at a thickness of 1 cm, 1.1 cm, 1.2 cm, 1.3 cm, 1.4 cm, 1.5 cm, 1.6 cm, 1.7 cm, 1.8 cm, 1.9 cm, 2 cm, 2.1 cm, 2.2 cm, 2.3 cm, 2.4 cm, 2.5 cm, or the like. Uniform drying of the flux can be further ensured if the flux is spread at a thickness within the above range. In a specific embodiment of the present disclosure, the flux is cooled to 90 to 100 °C in an atmosphere of a protective gas after undergoing the maintaining of temperature. In a specific embodiment of the present disclosure, the protective gas includes any one or more of nitrogen and inert gas. In a specific embodiment of the present disclosure, the flux is crushed and sieved after it is cooled. The dried flux is crushed and sieved to obtain a flux having a required particle size. The present disclosure also provides a system for drying flux, including: a casing and a conveying unit passing through the casing;

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wherein the casing includes a microwave drying chamber and a cooling chamber along a direction of conveyance performed by the conveying unit, and at least one microwave generator is arranged in the microwave drying chamber. The drying system of the present disclosure has a simple structure and can continuously dry the flux by using microwaves. In a specific embodiment of the present disclosure, two or more microwave generators are arranged in the microwave drying chamber. Specifically, the microwave generators may be distributed evenly in the microwave drying chamber. In a specific embodiment of the present disclosure, the interior of the microwave drying chamber is made of Teflon. When a plurality of microwave generators are used, the number of microwave generators to be turned on or off may be regulated to control the microwave power so as to provide different drying conditions. In a specific embodiment of the present disclosure, the microwave drying chamber is divided into a temperature raising zone and a temperature maintaining zone along the direction of conveyance performed by the conveying unit. The temperature raising zone is mainly configured to raise the temperature of the flux to a particular temperature under the action of microwaves, and the temperature maintaining zone is mainly configured to maintain the temperature of the flux that has its temperature raised in the temperature raising zone under the action of microwaves. In a specific embodiment of the present disclosure, the conveying unit includes a conveyor belt. The flux may be spread on the conveyor belt, and sequentially conveyed into the temperature raising zone, the temperature maintaining zone, and the cooling chamber in the casing via the conveyor belt and then conveyed out therefrom. The conveyance speed may be regulated according to the time required for each stage of the drying treatment, as long as the treatment time at different stages can be met. Specifically, the conveyance speed may be 0.01 to 0.5 m/min. When the conveyance speed is within the above range, the flux material has its temperature raised to the target temperature in the temperature raising zone and is then conveyed to the temperature maintaining zone where its temperature is maintained for a certain period of time, and then conveyed to the cooling chamber for being cooled. Optionally, the conveyor belt is made of Teflon.

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By using the above-mentioned material to make the conveyor belt

, corrosion of the conveyor belt by an exhaust gas generated during drying can be avoided to prolong the service life of the system. Moreover, the purity of the flux can be avoided from being affected by the corroded product. In a specific embodiment of the present disclosure, the system further includes a dehumidifying unit connected with the microwave drying chamber. In a specific embodiment of the present disclosure, the microwave drying chamber is provided with an air outlet, wherein the dehumidifying unit is connected with the air outlet. The dehumidifying unit communicates with the interior of the microwave drying chamber through the air outlet to draw the exhaust gas out therefrom. In a specific embodiment of the present disclosure, the microwave drying chamber is provided with an air inlet. In a specific embodiment of the present disclosure, the dehumidifying unit includes a dehumidifying fan, an exhaust gas treatment unit, and a detection unit which are connected in sequence. Specifically, the dehumidifying fan is connected with the air outlet via a pipe. The dehumidifying fan is configured to draw a high-temperature, high-humidity, and possibly corrosive gas generated during the drying from the microwave drying chamber and deliver the gas into the exhaust gas treatment unit, e.g. a special water tank, for treating the gas. In a specific embodiment of the present disclosure, the inner wall of the pipe is made of Teflon. The detection unit may detect the gas which is treated and discharged by the waste gas treatment unit. If the gas is detected substandard, the gas discharged by the waste gas treatment unit is delivered to the waste gas treatment unit again to obtain a gas meeting the emission requirements, which is then discharged to the outside. In a specific embodiment of the present disclosure, a temperature detection unit is arranged in the casing for detecting the temperature of each zone in the casing. Specifically, the temperature detection unit may be a thermometer. In a specific embodiment of the present disclosure, the system further includes a protective gas delivery unit connected with the cooling chamber. The protective gas delivery unit is connected with the cooling chamber and delivers a protective gas to the cooling chamber, so that the flux is cooled down under the atmosphere of the protective gas. In a specific embodiment of the present disclosure, the system further includes a crusher connected with the discharge end of the conveying unit. In a specific embodiment of the present disclosure, microwave suppressors are arranged outside the microwave drying chamber. Specifically, the

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microwave suppressors are arranged outside both the inlet end and the outlet end of the microwave drying chamber. Compared with the prior art, the present disclosure has the following advantageous effects: (1) In the present disclosure, a flux is dried using microwaves by simple processes and is heated uniformly, so that the dried flux product has high quality and has a uniform color, and a uniform drying effect is achieved with less energy at high efficiency. (2) The system for drying flux of the present disclosure has a simple structure, allows the selection of corresponding microwave power according to different flux types, and is operative continuously with high productivity. Brief Description of Drawings In order to more clearly illustrate technical solutions of specific embodiments of the present disclosure or of the prior art, drawings required to be used in the description of the specific embodiments or the prior art will be described briefly below. It is apparent that the drawings in the following description are illustrative of some embodiments of the present disclosure. It will be understood by those of ordinary skill in the art that other drawings can also be obtained from these drawings without any inventive effort. FIG. 1 is a schematic structural diagram of a system for drying flux according to an embodiment of the present disclosure.

Reference Numerals: 1-casing; 2-conveyor belt; 3-dehumidifying unit; 4-protective gas delivery unit; 5-crusher; 6-sieving machine; 7-weighing and packaging unit; 8-rack; 11-microwave drying chamber; 12-cooling chamber; 21-feeding port; 22-discharge port; 31-dehumidifying fan; 32-waste gas treatment unit; 111-temperature raising zone; 112-temperature maintaining zone; 113-microwave generator; 114-observationwindow; 115-microwavesuppressor. Detailed Description of Embodiments The technical solutions of the present disclosure will be described below clearly and completely with reference to the accompanying drawings and specific embodiments. However, it will be understood by those skilled in the art

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that embodiments described below are some, rather than all of the examples of the present disclosure, are intended to illustrate the present disclosure only, and should not be considered as limiting the scope of the present disclosure. All other embodiments obtained by those of ordinary skill in the art in light of the embodiments of the present disclosure without inventive efforts will fall within the scope of the present disclosure as claimed. Embodiments are carried out in accordance with conventional conditions or conditions recommended by the manufacturers if no specific conditions are specified in the embodiments. Reagents or instruments used are all commercially available conventional products if their manufacturers are not specified. In the description of the present disclosure, it should be noted that orientation or positional relations indicated by terms such as "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", and "outside" are the orientation or positional relations shown based on the figures, and these terms are intended only to facilitate the description of the present disclosure and simplify the description, but not intended to indicate or imply that the referred devices or elements must be in a particular orientation or constructed or operated in the particular orientation, and therefore should not be construed as limiting the present disclosure. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and should not be understood as an indication or implication of relative importance. In the description of the present disclosure, it should be noted that the terms "mounted", "coupled", and "connected" should be understood broadly unless otherwise expressly specified or defined. For example, a connection may be fixed connection or detachable connection or integral connection, may be mechanical connection or electric connection, or may be direct connection or indirect connection via an intermediate medium or internal communication between two elements. The specific meanings of the above-mentioned terms in the present disclosure can be understood by those of ordinary skill in the art according to specific situations. FIG. 1 is a schematic structural diagram of a system for drying a flux according to an embodiment of the present disclosure. Referring to FIG. 1, the system for drying flux according to this embodiment includes a casing 1 and a conveying unit passing through the casing 1. Specifically, the conveying unit may include a conveyor belt 2 and a electric conveying motor (not shown in the figures). The electric conveying motor controls running of the conveyor belt 2. A flux may be spread (distributed) on the conveyor belt 2 and sequentially conveyed into a microwave drying chamber 11 and a cooling chamber 12 in the casing 1 via the conveyor belt 2 and then taken out therefrom. Optionally, material of the conveyor belt 2 is PTFE(Teflon). For example, the conveyor belt may be made of a Teflon mesh belt or a Teflon fabric resistant to

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high temperature. With application of the Teflon material, corrosion of the conveyor belt by an exhaust gas generated during drying can be avoided to prolong the service life of the system. Moreover, the purity of the flux can be avoided from being affected by the corrosion products. In a specific embodiment, the casing 1 includes a microwave drying chamber 11 and a cooling chamber 12 along a direction of conveyance by the conveyor belt 2 of the conveying unit. A microwave generator 113 is arranged in the microwave drying chamber 11. Optionally, the microwave drying chamber 11 is provided with an observation window 114 for observing a situation inside the microwave drying chamber 11. Optionally, two or more microwave generators 113 are arranged in the microwave drying chamber 11. Specifically, the two or more microwave generators 113 may be distributed evenly in the microwave drying chamber 11. When a plurality of microwave generators 113 are used, it is feasible to regulate the number of microwave generators 113 to be turned on or off. so as to control the microwave power so as to provide different drying conditions. In a specific embodiment, the microwave drying chamber 11 is divided into a temperature raising zone 111 and a temperature maintaining zone 112 along the direction of conveyance by the conveyor belt 2 of the conveying unit. The temperature raising zone 111 is configured to raise the temperature of the flux to a particular temperature under the action of microwaves, and the temperature maintaining zone 112 is configured to maintain the temperature of the flux that has its temperature raised in the temperature raising zone 111 under the action of microwaves. In a specific embodiment, the system further includes a dehumidifying unit 3. The dehumidifying unit 3 is connected with the microwave drying chamber 11. Preferably, the microwave drying chamber 11 is provided with an air outlet, and the dehumidifying unit 3 is connected with the air outlet so as to communicate with the microwave drying chamber 11 to draw out the exhaust gas generated during drying. In a specific embodiment, the dehumidifying unit 3 includes a dehumidifying fan 31, an exhaust gas treatment unit 32, and a detection unit which are connected in sequence. The dehumidifying fan 31 is connected with the air outlet via a pipe. The dehumidifying fan 31 draws a high-temperature, high-humidity, and possibly corrosive gas generated during drying from the microwave drying chamber 11 and delivers the gas into the exhaust gas treatment unit 32 such as a special water tank for treating the gas. In a specific embodiment of the present disclosure, the inner wall of the pipe is made of Teflon. The detection unit may detect the gas which has been treated and discharged by the waste gas treatment unit 32. If the gas is detected

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substandard, the gas discharged by the waste gas treatment unit 32 is delivered to the waste gas treatment unit 32 again to obtain a gas meeting the emission requirements, which is then discharged to the outside. In a specific embodiment of the present disclosure, temperature detection units (not shown) are arranged in the casing 1 and are configured to detect the temperature of each zone in the casing 1. Specifically, the temperature detection units may be thermometers. In a specific embodiment of the present disclosure, the system further includes a protective gas delivery unit 4 connected with the cooling chamber 12. The protective gas delivery unit 4 is connected with the cooling chamber 12 and delivers a protective gas to the cooling chamber 12, so that the flux is cooled down under the atmosphere of the protective gas. In a specific embodiment of the present disclosure, microwave suppressors 115 are arranged outside the microwave drying chamber 11. Specifically, the microwave suppressors 115 are arranged outside both the inlet end and the outlet end of the microwave drying chamber 11. In a specific embodiment of the present disclosure, the system further includes a crusher (breaker) 5. The crusher 5 is connected with a discharge port 22 at the discharge end of the conveyor belt 2 for crushing the dried flux. The crushed flux is sieved (screened) by a sieving (screening) machine 6 to obtain a flux having the required particle size. The flux with a too large particle size is conveyed into the crusher 5 again to be crushed. In a specific embodiment of the present disclosure, the system further includes a weighing and packaging unit 7 which is connected with the sieving machine 6. The weighing and packaging unit 7 is configured to weigh and package the flux having the required particle size that has been sieved by the sieving machine 6. In a specific embodiment of the present disclosure, the system further includes a feeding unit connected with the feeding end of the conveying unit through a feeding port 21. The feeding unit is configured to spread and distribute the flux evenly on the conveyor belt of the conveying unit. In a specific embodiment of the present disclosure, the casing 1 and the conveyor belt 2 may be supported by a rack (or frame) 8.

Example 1 A method for drying a flux material according to this example includes the steps of:

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(1) passing a flux to be dried through a feeding unit and spreading the flux on the conveyor belt so that the flux material is distributed evenly on the conveyor belt and has a thickness of 1 cm; (2) conveying into the temperature raising zone of the microwave drying chamber the flux which has been well spread at a constant speed by the conveyor belt, activating microwaves at a microwave power of 15 kw and at the same time turning on the dehumidifying unit, wherein the flux material reaches a temperature of 200 to 250 °C, for example, 230 °C, in the temperature raising zone after a period of 15 min; (3) conveying into the temperature maintaining zone the high-temperature dried flux obtained in the temperature raising zone by the conveyor belt further for a maintaining of temperature , wherein the maintaining of temperature is performed at a microwave power of about 12 kw so as to ensure a temperature within the range of 200 to 250 °C, adjusting the magnitude of the microwave power to ensure the temperature, turning on the dehumidifying unit, wherein the maintaining of temperature is performed for a period of 30 min; (4) conveying into the cooling chamber the flux with its temperature maintained by the conveyor belt and delivering nitrogen into the cooling chamber by the protective gas delivery unit so that the flux is cooled to 90 to 100 °C in an atmosphere of nitrogen, and then conveying the flux by the conveyor belt from the discharge end to the crusher for crushing the flux, and then sieving the flux to obtain flux powder having a required particle size, wherein the particle size may be adjusted as actually required; (5) inspecting, weighing, and packaging the flux powder obtained in step (4) to obtain a finished product. In the above steps, the exhaust gas drawn (extracted) by the dehumidifying unit is delivered to a special water tank for treating the exhaust gas. The treated gas is discharged to the outside if it is detected to meet the emission requirements, or is delivered again to the special water tank for treatment if it does not meet the emission requirements.

Example 2 A method for drying a flux material according to this example includes the steps of: (1) passing a flux to be dried through the feeding unit and spreading the flux on the conveyor belt so that the flux material is distributed evenly on the conveyor belt and has a thickness of 2.5 cm; (2) conveying into the temperature raising zone of the microwave drying chamber the flux which has been well spread at a constant speed by the

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conveyor belt, activating microwaves at a microwave power of 15 kw and at the same time turning on the dehumidifying unit, wherein the flux material reaches a temperature of 200 to 250 °C, for example, 230 °C, in the temperature raising zone after a period of 12 min; (3) conveying into the temperature maintaining zone the high-temperature dried flux obtained in the temperature raising zone by the conveyor belt further for a maintaining of temperature, wherein the maintaining of temperature is performed at a microwave power of about 12 kw so as to ensure a temperature within the range of 200 to 250 °C, adjusting the magnitude of the microwave power to ensure the temperature, turning on the dehumidifying unit, wherein the maintaining of temperature is performed for a period of 29 min; (4) conveying into the cooling chamber the flux with its temperature maintained by the conveyor belt and delivering nitrogen into the cooling chamber by the protective gas delivery unit so that the flux is cooled to 90 to 100 °C in an atmosphere of nitrogen, and then conveying the flux by the conveyor belt from the discharge end to the crusher for crushing the flux, and then sieving the flux to obtain flux powder having a required particle size, wherein the particle size may be adjusted as actually required; (5) inspecting, weighing, and packaging the flux powder obtained in step (4) to obtain the finished product. In the above steps, the exhaust gas drawn by the dehumidifying unit is delivered to a special water tank for treating the exhaust gas. The treated gas is discharged to the outside if it is detected to meet the emission requirements, or is delivered again to the special water tank for treatment if it does not meet the emission requirements.

Example 3 A method for drying a flux material according to this example includes the steps of: (1) passing a flux to be dried through the feeding unit and spreading the flux on the conveyor belt so that the flux material is distributed evenly on the conveyor belt and has a thickness of 1 cm; (2) conveying into the temperature raising zone of the microwave drying chamber the flux which has been well spread at a constant speed by the conveyor belt, activating microwaves at a microwave power of 15 kw and at the same time turning on the dehumidifying unit, wherein the flux material reaches a temperature of 200 to 250 °C, for example, 230 °C, in the temperature raising zone after a period of 6 min;

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(3) conveying into the temperature maintaining zone the high-temperature dried flux obtained in the temperature raising zone by the conveyor belt further for a maintaining of temperature, wherein the maintaining of temperature is performed at a microwave power of about 12 kw so as to ensure a temperature within the range of 200 to 250 °C, the temperature is ensured by adjusting the magnitude of the microwave power, the dehumidifying unit is turned on, and the maintaining of temperature is performed for a period of 12 min; (4) conveying into the cooling chamber the flux with its temperature maintained by the conveyor belt and delivering nitrogen into the cooling chamber by the protective gas delivery unit so that the flux is cooled to 90 to 100 °C in an atmosphere of nitrogen, and then conveying the flux by the conveyor belt from the discharge end to the crusher for crushing the flux, and then sieving the flux to obtain flux powder having a required particle size, wherein the particle size may be adjusted as actually required; (5) inspecting, weighing, and packaging the flux powder obtained in step (4) to obtain the finished product. In the above steps, the exhaust gas drawn by the dehumidifying unit is delivered to a special water tank for treating the exhaust gas. The treated gas is discharged to the outside if it is detected to meet the emission requirements, or is delivered again to the special water tank for treatment if it does not meet the emission requirements.

Example 4 A method for drying a flux material according to this example includes the steps of: (1) passing a flux-to-be-dried through the feeding unit and spreading the flux on the conveyor belt so that the flux material is distributed evenly on the conveyor belt and has a thickness of 2.5 cm; (2) conveying into the temperature raising zone of the microwave drying chamber the flux which has been well spread at a constant speed by the conveyor belt, activating microwaves at a microwave power of 15 kw and at the same time turning on the dehumidifying unit, wherein the flux material reaches a temperature of 200 to 250 °C, for example, 230 °C, in the temperature raising zone after a period of 8 min; (3) conveying into the temperature maintaining zone the high-temperature dried flux obtained in the temperature raising zone by the conveyor belt further for a maintaining of temperature, wherein the maintaining of temperature is performed at a microwave power of about 12 kw so as to ensure a temperature within the range of 200 to 250 °C, the temperature is ensured by adjusting the

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magnitude of the microwave power, the dehumidifying unit is turned on, and the maintaining of temperature is performed for a period of 14 min; (4) conveying into the cooling chamber the flux with its temperature maintained into the cooling chamber by the conveyor belt and delivering nitrogen by the protective gas delivery unit so that the flux is cooled to 90 to 100 °C in an atmosphere of nitrogen, and then conveying the flux by the conveyor belt from the discharge end to the crusher for crushing the flux, and then sieving the flux to obtain flux powder having a required particle size, wherein the particle size may be adjusted as actually required; (5) inspecting, weighing, and packaging the flux powder obtained in step (4) to obtain the finished product. In the above steps, the exhaust gas drawn by the dehumidifying unit is delivered to a special water tank for treating the exhaust gas. The treated gas is discharged to the outside if it is detected to meet the emission requirements, or is delivered again to the special water tank for treatment if it does not meet the emission requirements.

Comparative Example 1 A prior art baking method is used in Comparative Example 1, wherein a flux the same as that in Example 4 is placed in a drying box coated with Teflon at 230 °C and baked for 25 min to obtain a dried flux.

Comparative Example 2 A prior art baking method was is in Comparative Example 2, wherein a flux the same as that in Example 1 was placed in a drying box coated with Teflon at 230 °C and baked for 45 min to obtain a dried flux.

Experimental Example 1 In order to compare and illustrate the properties of the flux products obtained by the drying methods of the various examples of the present disclosure and the comparative examples, the moisture content and color of each of the obtained flux products are tested. The test results are shown in Table 1 below.

Table 1. Results of Testing on Properties of Different Flux Products Initial Moisture Final Moisture No. Flux Type Color Content (wt%) Content (wt%)

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Relatively uniform Example 1 Paste Flux 8 50.01 and even

Granular Relatively uniform Example 2 2.3 50.01 Flux and even

Powdered Relatively uniform Example 3 0.9 50.01 Flux and even

Powdered Relatively uniform Example 4 1.5 50.01 Flux and even

A significant color Comparative Powdered 1.5 0.05 difference was Example 1 Flux observed

A significant color Comparative Paste Flux 8 0.1 difference was Example 2 observed

Experimental Example 2 The following test is performed to compare and illustrate the efficiency and energy consumption of the drying methods of the examples of the present disclosure and the drying methods of the comparative examples. The test results are shown in Table 2. Testing Method: Group 1: a certain mass of flux (with an initial moisture content of 1.5 wt%) is dried by using the method of Example 1, wherein the flux is spread at a thickness of 2.5 cm and is heated up to a temperature of 230 °C at a microwave power of 15 kw and maintained at the temperature. Group 2: the same mass of the same flux is dried by using the method of Comparative Example 1, wherein the flux is spread at a thickness of 2.5 cm and placed in a drying box at a temperature of 230 °C. The time and unit energy consumption required and the color of the flux are measured when each of the fluxes in Group 1 and Group 2 reached a moisture content of 0.1 wt%. Table 2. Test Results of Group 1 and Group 2

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Drying Unit Energy Final Moisture No. Color Time (h) Consumption Content (wt%) (kW-h-kg 1

) Group 1 0.1 Uniform 15 min 3.18

A color difference 44 min 5.36 Group 2 0.1 was observed

It can be seen from the above test results that the drying method of the present disclosure allows a reduction of the drying time by about 2/3 and a reduction of the energy consumption by 40% compared with the traditional drying method. Therefore, this drying method is suitable for application on a large scale.

Finally, it should be noted that the above embodiments are merely intended to illustrate the technical solutions of the present disclosure, but not intended to limit the present disclosure. Although the present disclosure has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that the technical solutions disclosed in the foregoing embodiments may still be modified, or some or all of the technical features thereof may be replaced with equivalents; and such modifications or replacements will not cause the essence of the corresponding technical solutions to depart from the scope of the technical solutions of the embodiments of the present disclosure.

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Claims

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What is claimed is: 1. A method for drying a flux, comprising a step of: drying a flux under action of microwaves, wherein the flux is selected from a powdered flux, a paste flux, and a granular flux.
2. The method for drying a flux according to claim 1, wherein the microwaves have a power of 10 to 20 kW.
3. The method for drying a flux according to claim 2, wherein the microwaves have a power of 12 to 15kW.
4. The method for drying a flux according to any one of claims 1 to 3, wherein the drying comprises: maintaining temperature of the flux after the flux reaches a temperature of 200 to 250 °C.
5. The method for drying a flux according to claim 4, wherein the flux reaches a temperature of 200 to 250 °C after 6 to 15 minutes.
6. The method for drying a flux according to claim 4 or 5, wherein the maintaining of temperature is performed for a period of 12 to 30 min.
7. The method for drying a flux according to any one of claims 1 to 6, wherein the flux is spread in advance at a thickness of 1 to 2.5 cm before the drying.
8. The method for drying a flux according to any one of claims 4 to 7, wherein the flux is cooled to 90 to 100 °C in an atmosphere of a protective gas after undergoing the maintaining of temperature.
9. The method for drying a flux according to claim 8, wherein the protective gas comprises any one or more of nitrogen and an inert gas.
10. The method for drying a flux according to claim 8 or 9, wherein the flux is crushed and sieved after it is cooled.
11. A system for drying flux, comprising: a casing and a conveying unit passing through the casing, wherein the casing comprises a microwave drying chamber and a cooling chamber along a direction of conveyance performed by the conveying unit, and a microwave generator is arranged in the microwave drying chamber.
12. The system for drying flux according to claim 11, wherein two or more microwave generators are arranged in the microwave drying chamber.

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13. The system for drying flux according to claim 11 or 12, wherein the microwave drying chamber is divided into a temperature raising zone and a temperature maintaining zone along the direction of conveyance performed by the conveying unit.
14. The system for drying flux according to any one of claims 11 to 13, wherein the conveying unit comprises a conveyor belt, and the conveyor belt is made of Teflon.
15. The system for drying flux according to any one of claims 11 to 14, further comprising a dehumidifying unit connected with the microwave drying chamber.
16. The system for drying flux according to claim 15, wherein the microwave drying chamber is provided with an air outlet, and the dehumidifying unit is connected with the air outlet.
17. The system for drying flux according to any one of claims 11 to 16, further comprising a protective gas delivery unit connected with the cooling chamber.
18. The system for drying flux according to any one of claims 11 to 17, further comprising a crusher connected with a discharge end of the conveying unit.
19. The system for drying flux according to any one of claims 11 to 18, wherein a temperature detection unit is arranged in the casing.
20. The system for drying flux according to any one of claims 11 to 19, wherein a microwave suppressor is arranged outside the microwave drying chamber.

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ONU20018948AU 02 Sep 2020

Drawings 2020102102

FIG. 1

1/1

ONU20018948AU