Powder material production equipment and magnetic substance control and treatment method for powder materials

Abstract

An embodiment of the present invention relates to a powder material production device and a method for controlling and processing magnetic substances of the powder material. The processing method includes: heating the powder material production device to a heat treatment temperature; introducing a carburizing treatment gas source and a protective gas into the furnace body of the powder material production device at a set flow rate, keeping warm at the heat treatment temperature, and naturally cooling after reaching a set heat preservation time; during the heat preservation process, active carbon atoms decomposed from the carburizing treatment gas source penetrate into the austenite on the inner surface of the furnace body.

Description

Technical Field

[0001] The present invention relates to the technical field of material production quality control, and particularly to a powder material production device and a method for controlling and processing magnetic substances in powder materials. Background Art

[0002] Magnetic substances refer to materials that can respond to a magnetic field in a certain way. Generally, the so-called magnetic materials refer to ferromagnetic materials. Ferromagnetic materials are generally elements such as Fe, Co, Ni and their alloys, rare earth elements and their alloys, as well as some compounds of Mn.

[0003] In battery materials, magnetic substances are generally introduced through raw materials or during the production process, which will seriously affect the electrochemical performance of the battery. They will not only reduce the proportion of active materials in the electrode, but also catalyze the side reactions between the electrode material and the electrolyte, and even pierce the diaphragm, causing potential safety hazards. Therefore, it is necessary to control from the source. In addition, in the field of powder materials, since most of the production equipment for powder materials is made of stainless steel and galvanized steel plates, etc., the products often contain magnetic impurities such as iron, chromium, nickel and zinc. During the production process, due to the friction between the material and the equipment and the shedding of the inner surface alloy layer of the equipment itself after high-temperature treatment and aging, the magnetic substances in the material are too high. Therefore, the content requirements for such impurities in the standard are relatively strict (for example, magnetic substances in graphite materials ≤ 1.5 ppm, magnetic substances in lithium titanate materials ≤ 20 ppm, magnetic substances in silicon-based materials ≤ 2 ppm). If the magnetic substances in the material are too high, the subsequent demagnetization treatment not only increases the process and consumes a large amount of manpower and material resources, but also the magnetic substances are difficult to meet the technical requirements. Therefore, the pre-control method of magnetic substances is particularly important. Summary of the Invention

[0004] The purpose of the present invention is to provide a powder material production device and a method for controlling and processing magnetic substances in powder materials, so as to effectively control the magnetic substances in the powder materials processed by the powder material production device through pretreatment of the furnace body of the powder material production device.

[0005] For this purpose, in the first aspect, an embodiment of the present invention provides a method for controlling and processing magnetic substances in a powder material production device, including:

[0006] Raise the temperature of the powder material production device to the heat treatment temperature;

[0007] Introduce a carburizing treatment gas source and a protective gas into the furnace body of the powder material production device at a set flow rate, keep warm at the heat treatment temperature, and naturally cool down after reaching the set holding time;

[0008] During the heat preservation process, active carbon atoms decomposed from the carburizing treatment gas source penetrate into the austenite on the inner surface of the furnace body.

[0009] Preferably, the carburizing treatment gas source includes one or more of methane, ethane, acetylene, propylene, and propane; the flow rate of the carburizing treatment gas source is 1 L / min - 50 L / min;

[0010] The protective gas includes one or more of argon, nitrogen, and helium; the flow rate of the protective gas is 1.5 L / min - 150 L / min.

[0011] Preferably, the heat treatment temperature is 800 °C - 1000 °C; the heat preservation time is 1 - 24 hours.

[0012] Preferably, the magnetic substance includes: Fe, Cr, Ni;

[0013] After the control treatment of the magnetic substance, the total content of the magnetic substance in the powder material produced by the powder material production equipment is ≤ 2 ppm.

[0014] Preferably, the powder material production equipment is used to produce any one or more of the cathode material for lithium batteries, the anode material for lithium batteries, the cathode material for sodium batteries, the anode material for sodium batteries, the cathode material for lithium-sulfur batteries, the anode material for lithium-sulfur batteries, and other powder materials for secondary batteries.

[0015] In a second aspect, an embodiment of the present invention provides a method for controlling the magnetic substance of a powder material, including:

[0016] Before the powder material production and processing step, the powder material production equipment is heated to the heat treatment temperature;

[0017] The carburizing treatment gas source and the protective gas source are introduced into the furnace body of the powder material production equipment according to a set flow rate, heat preservation is carried out at the heat treatment temperature, and after reaching the set heat preservation time, natural cooling is carried out;

[0018] During the heat preservation process, the carburizing treatment gas source decomposes active carbon atoms into the austenite on the inner surface of the furnace body, thereby controlling the magnetic substance on the inner surface of the furnace body to enter the powder material during the powder material production and processing step.

[0019] Preferably, the carburizing treatment gas source includes one or more of methane, ethane, acetylene, propylene, and propane; the flow rate of the carburizing treatment gas source is 1 L / min - 50 L / min;

[0020] The protective gas includes one or more of argon, nitrogen, and helium; the flow rate of the protective gas is 1.5 L / min - 150 L / min.

[0021] Preferably, the heat treatment temperature is 800 °C - 1000 °C; the heat preservation time is 1 - 24 hours.

[0022] Preferably, the magnetic substance includes: Fe, Cr, Ni;

[0023] After the control treatment of the magnetic substance, the total content of the magnetic substance in the powder material produced by the powder material production equipment is ≤2 ppm.

[0024] Preferably, the powder material includes any one of: lithium battery cathode material, lithium battery anode material, sodium battery cathode material, sodium battery anode material, lithium-sulfur battery cathode material, lithium-sulfur battery anode material, and other powder materials for secondary batteries.

[0025] In the embodiment of the present invention, through the carburizing treatment of the production equipment with an organic gas source, active carbon atoms are decomposed at high temperature and infiltrated into the surface of the steel parts in the furnace body. After the active carbon atoms are absorbed by the surface of the steel parts in the furnace body, they are dissolved into the surface austenite, increasing the carbon content in the austenite. The increase in the surface carbon content causes a carbon atom concentration difference between the inner surface and the outer surface of the furnace body steel parts, and the carbon on the surface continues to diffuse inward, so that the surface of the steel parts has high hardness and wear resistance. The protection of the carbon layer makes the alloy substances on the surface of the steel parts not easy to fall off, thereby effectively controlling the magnetic substances. Description of the Drawings

[0026] Figure 1 It is a flowchart of the method for controlling the magnetic substances of the powder material production equipment provided by the embodiment of the present invention;

[0027] Figure 2 It is a flowchart of the method for controlling the magnetic substances of the powder material provided by the embodiment of the present invention. Detailed Embodiments

[0028] The technical solutions of the present invention will be further described in detail below with reference to the drawings and embodiments.

[0029] The embodiment of the present invention provides a method for controlling the magnetic substances of a powder material production equipment to control the influence of the magnetic substances of the battery powder material production equipment on the production and processing quality of the battery powder material. The main steps are as Figure 1 shown and include:

[0030] Step 110, heating the powder material production equipment to the heat treatment temperature;

[0031] Specifically, the powder material production equipment refers to a high-temperature equipment for producing battery powder materials. In the present invention, a rotary furnace is taken as an example for illustration, but those skilled in the art are aware that this solution can also be used for other commonly used battery powder material production equipment in the industry.

[0032] The rotary furnace may specifically include a continuous rotary furnace and an intermittent rotary furnace.

[0033] The heat treatment temperature is 800°C - 1000°C.

[0034] Step 120: Introduce a carburizing treatment gas source and a protective gas into the furnace body of the powder material production equipment at a set flow rate, keep warm at the heat treatment temperature, and then cool naturally after reaching the set holding time.

[0035] Specifically, the carburizing treatment gas source includes one or more of methane, ethane, acetylene, propylene, and propane; the flow rate of the carburizing treatment gas source is 1 L / min - 50 L / min, preferably 1 L / min - 25 L / min; the protective gas includes one or more of argon, nitrogen, and helium; the flow rate of the protective gas is 1.5 L / min - 150 L / min.

[0036] The heat treatment temperature is 800°C - 1000°C, and the holding time is 1 - 24 hours. Preferably, the holding time is 1 - 12 hours.

[0037] Step 130: During the holding process, the carburizing treatment gas source decomposes to release active carbon atoms, which penetrate into the austenite on the inner surface of the furnace body.

[0038] The powder material production equipment of the present invention is used to produce any one or more of the positive electrode materials for lithium batteries, negative electrode materials for lithium batteries, positive electrode materials for sodium batteries, negative electrode materials for sodium batteries, positive electrode materials for lithium-sulfur batteries, negative electrode materials for lithium-sulfur batteries, and other powder materials for secondary batteries.

[0039] In the embodiment of the present invention, through the organic gas source carburizing treatment of the production equipment, active carbon atoms are decomposed at high temperature and penetrate into the surface of the steel parts in the furnace body. After being absorbed by the surface of the steel parts in the furnace body, the active carbon atoms dissolve into the surface austenite, increasing the carbon content in the austenite. The increase in the surface carbon content causes a carbon atom concentration difference between the inner surface and the outer surface of the furnace body steel parts, and the carbon on the surface continues to diffuse inward, so that the surface of the steel parts has high hardness and wear resistance. The protection of the carbon layer makes the alloy substances on the surface of the steel parts not easy to fall off, thereby effectively controlling magnetic substances and being able to effectively reduce the doping of magnetic substances into the powder materials produced by this production equipment. It has been verified that for the production equipment treated by the above method, the total content of magnetic substances (Fe, Cr, Ni) in the produced powder materials ≤ 2 ppm.

[0040] Correspondingly, the present invention also provides a method for controlling and treating magnetic substances in powder materials, which controls and reduces the incorporation of magnetic substances into battery powder materials during production and processing by pre-treating the powder material production and processing equipment. The main steps are as Figure 2 shown and include:

[0041] Step 210: Before the powder material production and processing step, heat the powder material production equipment to the heat treatment temperature.

[0042] Specifically, the treatment of the powder material production and processing equipment is carried out before the production of the powder material. In practical applications, the magnetic substance control treatment of the powder material production equipment can be added once between 3-4 production cycles.

[0043] The heat treatment temperature is 800°C - 1000°C.

[0044] Step 220: Introduce the carburizing treatment gas source and protective gas into the furnace body of the powder material production equipment at a set flow rate, keep warm at the heat treatment temperature, and naturally cool down after reaching the set holding time;

[0045] Specifically, the carburizing treatment gas source includes one or more of methane, ethane, acetylene, propylene, and propane; the flow rate of the carburizing treatment gas source is 1 L / min - 50 L / min, preferably 1 L / min - 25 L / min; the protective gas includes one or more of argon, nitrogen, and helium; the flow rate of the protective gas is 1.5 L / min - 150 L / min.

[0046] The heat treatment temperature is 800°C - 1000°C, and the holding time is 1 - 24 hours. Preferably, the holding time is 1 - 12 hours.

[0047] Step 230: During the heat preservation process, the carburizing treatment gas source decomposes to release active carbon atoms, which penetrate into the austenite on the inner surface of the furnace body, thereby controlling the magnetic substances on the inner surface of the furnace body from entering the powder material during the powder material production and processing steps.

[0048] The powder material includes any one of the following: lithium battery positive electrode material, lithium battery negative electrode material, sodium battery positive electrode material, sodium battery negative electrode material, lithium-sulfur battery positive electrode material, lithium-sulfur battery negative electrode material, and other powder materials for secondary batteries.

[0049] In the embodiment of the present invention, before the production of the powder material, the production equipment is subjected to organic gas source carburizing treatment. At high temperature, active carbon atoms are decomposed and penetrate into the surface of the steel parts in the furnace body. After being absorbed by the surface of the steel parts in the furnace body, the active carbon atoms dissolve into the surface austenite, increasing the carbon content in the austenite. The increase in the surface carbon content causes a carbon atom concentration difference between the inner surface and the outer surface of the furnace body steel parts, and the carbon on the surface continues to diffuse into the interior, so that the surface of the steel parts has high hardness and wear resistance. The protection of the carbon layer makes the alloy substances on the surface of the steel parts not easily fall off, thereby effectively controlling the magnetic substances and being able to effectively reduce the doping of magnetic substances into the powder material produced by this production equipment. It has been verified that for the production equipment treated by the above method, the total content of magnetic substances (Fe, Cr, Ni) in the produced powder material ≤ 2 ppm.

[0050] The following is further illustrated through several specific examples.

[0051] Example 1

[0052] Example 1 provides a heat treatment method for powder materials.

[0053] First, heat the rotary furnace to 850 °C, then introduce a mixture of acetylene and argon into the furnace. The gas flow rate of acetylene is 6 L / min, and the gas flow rate of argon is 10 L / min. After holding for 12 hours, let it cool naturally to complete the carburizing treatment.

[0054] Perform vapor deposition carbon coating treatment on the powder material in the furnace after the above pretreatment to prepare the anode material, and test the magnetic substance parameters of the sintered material.

[0055] Specific test method: Weigh 200 g of the sintered material as the test sample to be tested, adsorb the magnetic substances with a magnetic bar, add the magnetic substances adsorbed by the magnetic bar to aqua regia, heat and digest to a constant volume, and then test. The total content of magnetic substances Fe, Cr, and Ni is measured to be 0.9 ppm.

[0056] Example 2

[0057] Example 2 provides a heat treatment method for powder materials.

[0058] First, heat the rotary furnace to 950 °C, then introduce a mixture of propane and nitrogen into the furnace. The gas flow rate of propane is 8 L / min, and the gas flow rate of nitrogen is 24 L / min. After holding for 6 hours, let it cool naturally to complete the carburizing treatment.

[0059] Perform vapor deposition carbon coating treatment on the powder material in the furnace after the above pretreatment to prepare the anode material, and test the magnetic substance parameters of the sintered material. The method is the same as that in Example 1. The total content of magnetic substances Fe, Cr, and Ni is measured to be 1.6 ppm.

[0060] Example 3

[0061] Example 3 provides a heat treatment method for powder materials.

[0062] First, heat the rotary furnace to 1000 °C, then introduce a mixture of propylene and argon into the furnace. The gas flow rate of propylene is 8 L / min, and the gas flow rate of argon is 16 L / min. After holding for 5 hours, let it cool naturally to complete the carburizing treatment.

[0063] Perform vapor deposition carbon coating treatment on the powder material in the furnace after the above pretreatment to prepare the anode material, and test the magnetic substance parameters of the sintered material. The method is the same as that in Example 1. The total content of magnetic substances Fe, Cr, and Ni is measured to be 1.1 ppm.

[0064] For better comparison, we prepared a comparative sample according to the following method.

[0065] Comparative Example 1

[0066] This comparative example provides a method for comparison with Example 1.

[0067] The equipment directly performs carbon deposition on the powder material by vapor deposition without magnetic material control treatment to prepare the anode material, and the magnetic material parameters of the sintered material are tested. The method is the same as that in Example 1, and the total content of magnetic materials Fe, Cr, and Ni is measured to be 42.6 ppm.

[0068] Comparative Example 2

[0069] This comparative example provides a method for comparison with Example 1.

[0070] First, the rotary furnace is heated to 650 °C, then a mixed gas of acetylene and argon is introduced into the furnace. The gas volume of acetylene is 6 L / min, and the gas volume of argon is 10 L / min. After heat preservation for 12 hours, it is naturally cooled to complete the carburizing treatment.

[0071] In the furnace after the above pretreatment, carbon deposition on the powder material by vapor deposition is carried out to prepare the anode material, and the magnetic material parameters of the sintered material are tested. The method is the same as that in Example 1, and the total content of magnetic materials Fe, Cr, and Ni is measured to be 29.0 ppm.

[0072] Comparative Example 3

[0073] This comparative example provides a method for comparison with Example 1.

[0074] First, the rotary furnace is heated to 850 °C, then a mixed gas of acetylene and argon is introduced into the furnace. The gas volume of acetylene is 6 L / min, and the gas volume of argon is 10 L / min. After heat preservation for 36 hours, it is naturally cooled to complete the carburizing treatment.

[0075] In the furnace after the above pretreatment, carbon deposition on the powder material by vapor deposition is carried out to prepare the anode material, and the magnetic material parameters of the sintered material are tested. The method is the same as that in Example 1, and the total content of magnetic materials Fe, Cr, and Ni is measured to be 0.8 ppm.

[0076] In the above examples and comparative examples, the process conditions for carbon deposition on the powder material by vapor deposition to prepare the anode material are the same.

[0077] The test results of the powder materials in the above Examples 1 - 3 and Comparative Examples 1 - 3 are listed in Table 1 for more intuitive comparison.

[0078]

[0079] Table 1

[0080] As can be seen from the embodiments in the figure, when the equipment is subjected to magnetic substance control treatment and then vapor deposition of the negative electrode raw material, the magnetic substances are well controlled and all meet the technical standards. When the equipment is directly coated without magnetic substance control treatment, the inner surface alloy layer is not protected and the magnetic substances increase sharply. When the heat treatment temperature in Comparative Example 2 is lower than 800 °C, since the carbon atoms lack sufficient activity at this time and carburization cannot be achieved on the surface of the alloy layer, the magnetic substances also continue to increase. In Comparative Example 3, after long-term heat preservation carburization, although the magnetic substances are effectively controlled, a large amount of carbon deposition is easily formed inside the equipment, affecting the physical properties of the material coating. At the same time, there are also problems of excessive energy consumption and high cost.

[0081] The present invention performs organic gas source carburization treatment on the production equipment and reasonably selects the temperature and time, so that the organic gas source decomposes into active carbon atoms at high temperature and penetrates into the surface of the steel parts in the furnace body. After the active carbon atoms are absorbed by the surface of the steel parts in the furnace body, they are dissolved into the surface austenite, increasing the carbon content in the austenite. The increase in the surface carbon content causes a carbon atom concentration difference between the inner surface and the outer surface of the steel parts in the furnace body, and the carbon on the surface continues to diffuse inward, so that the surface of the steel parts has high hardness and wear resistance. The protection of the carbon layer makes the alloy substances on the surface of the steel parts not easy to fall off, thereby effectively controlling the magnetic substances and being able to effectively reduce the doping of magnetic substances into the powder materials produced by the production equipment. It has been verified that for the production equipment treated by the above method, the total content of magnetic substances (Fe, Cr, Ni) in the produced powder materials ≤ 2 ppm.

[0082] The method involved in the present invention is compatible with the existing processes and equipment, is simple to implement, can greatly reduce the workload of post-magnetic treatment, and also plays a huge role in improving product quality.

[0083] The specific embodiments described above further elaborate on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above description is only the specific embodiments of the present invention and is not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for controlling and processing magnetic substances in powder materials, characterized in that, The processing method includes: Before the powder material production and processing steps, heating the powder material production equipment to the heat treatment temperature; Introducing a carburizing treatment gas source and a protective gas source into the furnace body of the powder material production equipment at a set flow rate, keeping warm at the heat treatment temperature, and naturally cooling after reaching the set holding time; During the heat preservation process, the carburizing treatment gas source decomposes to release active carbon atoms that penetrate into the austenite on the inner surface of the furnace body, thereby controlling the magnetic substances on the inner surface of the furnace body from entering the powder material during the powder material production and processing steps; The heat treatment temperature is 800°C - 1000°C; the holding time is 1 - 24 hours; The magnetic substances include: Fe, Cr, Ni; After the magnetic substance control treatment, the total content of magnetic substances in the powder material produced by the powder material production equipment is ≤2 ppm.

2. The method for controlling and processing magnetic substances according to claim 1, characterized in that, The carburizing treatment gas source includes one or more of methane, ethane, acetylene, propylene, and propane; the flow rate of the carburizing treatment gas source is 1 L / min - 50 L / min; The protective gas includes one or more of argon, nitrogen, and helium; the flow rate of the protective gas is 1.5 L / min - 150 L / min.

3. The method for controlling and processing magnetic substances according to claim 1, characterized in that, The powder material includes any one of positive electrode materials for lithium batteries, negative electrode materials for lithium batteries, positive electrode materials for sodium batteries, negative electrode materials for sodium batteries, positive electrode materials for lithium-sulfur batteries, negative electrode materials for lithium-sulfur batteries, and other powder materials for secondary batteries.

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