Vacuum closed-loop recycling method of recyclable camphor pore-forming agent with anti-explosion safety mechanism

Abstract

This invention discloses a vacuum closed-loop recovery method for recyclable camphor pore-forming agent with an explosion-proof safety mechanism, belonging to the field of porous material preparation technology. It solves the problems of existing camphor pore-forming processes lacking closed-loop recovery and posing explosion safety hazards. This invention constructs a complete explosion-proof safety mechanism through a full-process technology of pre-inert gas replacement, vacuum gradient sublimation camphor removal, and directional condensation solid-state recovery, eliminating the risk of camphor vapor explosion at the source. Simultaneously, it achieves a camphor pore-forming agent recovery rate of ≥90%, and the recovered camphor can be directly recycled and reused, with zero waste gas emissions throughout the process. This method is adaptable to pore-forming of various suitable matrix materials, is safe, low-cost, and suitable for large-scale industrial production.

Description

Technical Field

[0001] This invention belongs to the field of porous material preparation technology, specifically relating to a vacuum closed-loop recovery method for recyclable camphor pore-forming agent with an explosion-proof safety mechanism, applicable to the pore-forming preparation of various porous structural components such as energy storage electrodes, filter materials, and heat dissipation materials. Background Technology

[0002] Camphor, as an easily sublimated and residue-free organic pore-forming agent, has natural advantages in the preparation of porous materials, but its industrial application faces two major technological bottlenecks:

[0003] 1. Lack of mature closed-loop recycling technology: Existing technologies only use camphor as a one-time pore-forming agent, and the sublimated camphor gas is directly discharged, which not only causes a lot of raw material waste and increases production costs, but also pollutes the workshop environment; the few technologies that mention recycling have not formed a complete closed-loop reuse scheme and cannot be adapted to large-scale production.

[0004] 2. Lack of systematic explosion-proof safety mechanism: Camphor has a flash point of 65.6℃ (closed cup), an auto-ignition temperature of 466℃, and a vapor explosion limit of 0.6%~3.5% (volume fraction). The existing camphor pore-forming process does not have a systematic explosion-proof process flow. During the heating and sublimation stage, camphor vapor mixes with air in the closed furnace cavity, which can easily reach the explosion limit. It can be ignited and exploded by electric sparks or local overheating, posing a significant safety risk to production and failing to meet the safety requirements for industrial mass production.

[0005] Meanwhile, existing camphor-based pore-forming technologies limit the pore-forming agent to specific metal materials such as copper and nickel, resulting in a very narrow protection range that cannot meet the pore-forming needs of various new porous materials.

[0006] To address all the pain points of the existing technologies mentioned above, this invention proposes a complete solution that not only constructs a complete explosion-proof safety mechanism through a rigid process flow to eliminate the risk of explosion at the source, but also achieves a fully closed-loop recycling of camphor pore-forming agent, resulting in zero raw material waste and zero environmental pollution. At the same time, it is compatible with all suitable matrix materials for pore formation, taking into account safety, low cost, and universality. Summary of the Invention

[0007] Purpose of the invention

[0008] To overcome the problems of existing technologies, such as the inability to recycle camphor pore-forming agents in a closed loop, high production costs, lack of systematic explosion-proof safety mechanisms, and narrow applicability, this invention provides a vacuum closed-loop recycling method for recyclable camphor pore-forming agents with an explosion-proof safety mechanism. By constructing an explosion-proof system through a multi-step rigid process flow, the method achieves safe, low-cost, and closed-loop recycling of camphor pore-forming agents, making it suitable for large-scale industrial production.

[0009] Technical solution

[0010] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0011] A vacuum closed-loop recovery method for recyclable camphor pore-forming agent with an explosion-proof safety mechanism includes the following steps:

[0012] S1 Pre-forming: Camphor pore-forming agent is combined with pore-forming matrix material powder to prepare a blank containing camphor pore-forming agent;

[0013] S2 Pre-exposed Explosion-proof Replacement: The green blank is placed in a vacuum sintering furnace equipped with a condensation recovery module, an explosion-proof pressure relief unit, and an inert gas inlet unit. After the furnace body is closed, inert gas is introduced to completely replace the air in the furnace cavity, so that the oxygen volume fraction in the furnace cavity is ≤1%.

[0014] S3 Vacuum gradient sublimation camphor removal: After the replacement is completed, the vacuum is drawn to the target vacuum level, and the camphor pore-forming agent in the green blank is completely sublimated by gradient heating to form camphor gas. The furnace temperature does not exceed the camphor auto-ignition temperature throughout the process.

[0015] S4 Directional Condensation Solid Recovery: Camphor gas generated by sublimation flows directionally into the furnace body's matching condensation recovery module under vacuum pressure difference. The condensation temperature is set to complete the collection of solid camphor, realizing the closed-loop recovery of the pore-forming agent.

[0016] S5 Recycling: The solid camphor recovered in step S4 is directly reused in the blank preparation process of step S1, forming a closed-loop recycling.

[0017] Furthermore, in step S1, the matrix material powder used for pore formation is a powder material that can withstand temperatures not lower than 200°C and does not chemically react with camphor, and can be adapted to the pore formation preparation of various porous structural components.

[0018] Furthermore, in step S1, the form of camphor pore-forming agent used includes any one or more combinations of prefabricated three-dimensional interconnected camphor mesh, molten infused liquid camphor, and large-particle camphor powder, which can be flexibly adjusted according to the target pore structure.

[0019] Furthermore, in step S2, the inert gas is nitrogen or argon. After the replacement is completed, a slight positive pressure of 100Pa to 500Pa is maintained in the furnace cavity to prevent the infiltration of outside air. This eliminates the risk of camphor vapor mixing with oxygen to form an explosive mixture from the source, constituting the core pre-process of the explosion-proof safety mechanism of this invention.

[0020] Furthermore, in step S3, the process parameters for the vacuum gradient sublimation camphor removal are: vacuum degree ≤100Pa, gradient heating rate ≤5℃ / min, final temperature rise to 120℃~180℃, and holding time 2h~6h. Gradient heating can avoid local overheating that causes rapid vaporization of camphor, accurately control the sublimation rate, and at the same time, the temperature throughout the process is far below the camphor's auto-ignition temperature, completely eliminating the risk of auto-ignition, which constitutes the core process control link of the explosion-proof safety mechanism of this invention.

[0021] Furthermore, in step S4, the set temperature of the condensation recovery module is 0℃~20℃. Camphor gas is condensed in the module to form solid camphor. The entire process is sealed with no waste gas discharge, and the camphor recovery rate is ≥90%. The condensation recovery module has a detachable structure, and the recovered solid camphor can be directly taken out and reused without secondary purification.

[0022] Furthermore, after the vacuum sublimation process in step S3 is completed, there is no need to open the furnace or transfer the green blank. The reduction and sintering processes of the matrix material are completed sequentially in the same vacuum furnace. The entire process is protected by inert gas, which simplifies the process flow, improves production efficiency, and avoids the risk of explosion caused by opening the furnace midway, thus improving the explosion-proof safety mechanism.

[0023] Furthermore, the storage process for raw camphor and recycled camphor is as follows: the camphor is stored in a sealed, light-proof container at an ambient temperature of ≤30°C, with good ventilation, away from fire sources, heat sources and strong oxidizers, to prevent camphor from volatilizing at room temperature and forming explosive vapors, thus eliminating safety hazards in the storage process and forming a closed-loop process for the explosion-proof safety mechanism of this invention.

[0024] The core principle of explosion-proof safety mechanisms

[0025] The explosion-proof safety mechanism of this invention completely eliminates the three elements of camphor vapor explosion (explosive mixture, ignition source, and overpressure in a confined space) through a rigid process throughout the entire process, thus preventing the risk of explosion at the source.

[0026] 1. The pre-filled inert gas completely replaces the oxygen volume fraction in the furnace, reducing it to below 1%, thus completely destroying the conditions for camphor vapor to form an explosive mixture with oxygen and eliminating the possibility of explosion at the source.

[0027] 2. Gradient heating and vacuum sublimation, with the temperature throughout the process far below the auto-ignition temperature of camphor, while the low vacuum environment significantly reduces the concentration of camphor vapor, keeping it below the lower explosive limit throughout the process, thus eliminating the concentration conditions for auto-ignition and explosion.

[0028] 3. Fully enclosed micro-positive pressure protection prevents outside air from seeping in, and is equipped with an explosion-proof pressure relief unit to deal with abnormal working conditions, forming a full-process, no-dead-angle explosion-proof safety system that fully complies with the safety specifications of industrial production.

[0029] Beneficial effects

[0030] Compared with the prior art, the present invention has the following key beneficial effects:

[0031] 1. Construct a complete explosion-proof safety mechanism to completely eliminate explosion hazards: Through a rigid process of full replacement of inert gas in the pre-process, gradient temperature control sublimation, full-process sealed micro-positive pressure protection, and standardized storage, the formation of an explosive mixture of camphor vapor and oxygen is prevented from the source. The temperature throughout the process is far below the spontaneous combustion temperature of camphor, which fully complies with the safety specifications of industrial production and solves the core safety pain point that the camphor hole-making process cannot be applied on a large scale.

[0032] 2. Closed-loop recycling with zero waste and significantly reduced production costs: Through directional condensation solid-state recycling, the camphor pore-forming agent recovery rate is ≥90%. The recovered camphor can be directly reused in the pore-forming process, with no raw material waste, no waste gas emissions, and no environmental pollution. The overall pore-forming cost is only less than 1 / 5 of that of traditional pore-forming processes.

[0033] 3. Wide range of applications and strong versatility: Using functionally defined matrix materials, it is not limited to specific metal powders. All materials that can withstand temperatures not lower than 200℃ and do not chemically react with camphor can be adapted to this method, which can cover the pore-forming needs of porous materials in multiple fields such as energy storage, environmental protection, chemical industry, and heat dissipation.

[0034] 4. The process is extremely simple and suitable for large-scale mass production: the entire process of camphor removal, reduction and sintering is completed in a single vacuum furnace without the need for multiple process transfers. Camphor mesh can be prefabricated in batches and camphor can be recycled and reused. The process steps are simplified and can be directly connected to existing powder metallurgy production lines without the need for large-scale equipment modification.

[0035] 5. Excellent product performance with no impurities: Camphor leaves no residue after sublimation, and the prepared porous material has controllable pores and is free from impurities, fully meeting the requirements for high-end energy storage electrodes and precision filter materials. Detailed Implementation

[0036] The present invention will be further described in detail below with reference to specific embodiments. These embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present invention.

[0037] Example 1

[0038] This embodiment provides a closed-loop recovery method for camphor pore-forming agent with an explosion-proof safety mechanism, used for the preparation of porous copper electrodes. The specific steps are as follows:

[0039] 1. Pre-forming: Camphor is heated to a molten state and poured into an aluminum alloy mold. After cooling and demolding, a three-dimensional interconnected camphor mesh is obtained. 300-mesh pure copper powder and camphor mesh are laid alternately in layers and pressed to obtain a blank containing camphor pore-forming agent.

[0040] 2. Pre-explosion purging: Place the green blank in a vacuum sintering furnace equipped with a condensation recovery module, an explosion-proof pressure relief valve, and a nitrogen inlet unit. After closing the furnace, introduce high-purity nitrogen to completely replace the air in the furnace cavity. The oxygen volume fraction in the furnace is measured to be ≤0.8%. After the replacement is completed, maintain a slight positive pressure of 200Pa.

[0041] 3. Vacuum gradient sublimation camphor removal: Evacuate to 50 Pa, and gradually increase the temperature to 150 °C at a rate of 3 °C / min. Hold for 4 hours to allow the camphor in the green blank to completely sublimate and form camphor gas. There is no local overheating in the furnace throughout the process.

[0042] 4. Directional condensation solid-state recovery: Camphor gas generated by sublimation flows directionally into the condensation recovery module under vacuum pressure difference. The module is set at 10℃, and the camphor gas is condensed to form solid camphor. There is no waste gas emission throughout the process, and the camphor recovery rate is 93%.

[0043] 5. Subsequent processes: After the camphor removal is completed, there is no need to open the furnace. Hydrogen gas is introduced into the same furnace to complete the reduction of copper powder. Then the temperature is raised to 1050℃ for sintering. The porous copper electrode is obtained by cooling in the furnace.

[0044] 6. Recycling and reuse: The recovered solid camphor is directly remelted and poured to prepare camphor mesh sheets for use in the next batch of raw material preparation, forming a closed-loop recycling;

[0045] 7. Storage specifications: Both raw camphor and recycled camphor are stored in sealed brown PE drums. The temperature in the storage workshop is controlled at 18℃~25℃, with good ventilation, and away from heat sources and oxidants.

[0046] Example 2

[0047] This embodiment provides a closed-loop recovery method for camphor pore-forming agent with an explosion-proof safety mechanism, used in the preparation of porous titanium filter materials. The specific steps are as follows:

[0048] 1. Pre-forming: 200-mesh titanium powder and large-particle camphor powder are uniformly mixed and pressed to obtain a blank containing camphor pore-forming agent;

[0049] 2. Pre-explosion purging: Place the green blank in a vacuum sintering furnace, close the furnace body, and introduce high-purity argon gas to purge the air in the furnace until the oxygen volume fraction is ≤0.5%, maintaining a slight positive pressure of 300Pa;

[0050] 3. Vacuum gradient sublimation of camphor: Evacuate to 30 Pa, and gradually increase the temperature to 170 °C at a rate of 4 °C / min, and hold for 5 hours to allow the camphor to sublimate completely.

[0051] 4. Targeted condensation solid recovery: Camphor gas flows into a condensation recovery module set at 5℃, where it condenses to form solid camphor, with a recovery rate of 94%.

[0052] 5. Subsequent process: Vacuum sintering of titanium powder is completed in the same furnace to obtain porous titanium filter material;

[0053] 6. Recycling and reuse: Recycled camphor can be directly crushed back into powder for use in the preparation of the next batch of green blanks;

[0054] 7. Storage specifications: Camphor should be stored in a sealed metal container at an ambient temperature ≤28℃, away from light and in a well-ventilated area. It is strictly forbidden to store it together with oxidants.

[0055] Example 3 (Comparative Example of Explosion-Proof Mechanism Verification)

[0056] This comparative example uses the same process parameters as Example 1, omitting only the inert gas replacement step S2; all other conditions are identical. Results show that when the temperature reaches 130°C, the camphor vapor concentration inside the furnace reaches 2.1%, entering the explosion limit range. After the furnace spark detector detects an electrostatic spark, the explosion-proof pressure relief valve immediately activates, confirming that the process without an explosion-proof safety mechanism poses an extremely high explosion risk. In contrast, Examples 1 and 2 of this invention have no safety risks throughout the entire process; the camphor vapor concentration inside the furnace remains below the lower explosive limit, eliminating any explosion hazard and verifying the effectiveness of the explosion-proof safety mechanism of this invention. Attached Figure Description

[0057] Figure 1 is a process flow diagram of the vacuum closed-loop recovery method of recyclable camphor pore-forming agent with explosion-proof safety mechanism according to the present invention.

[0058] Explanation of reference numerals in the attached figures:

[0059] 1 - Camphor pore-forming agent preparation process; 2 - Raw blank preforming process; 3 - Pre-exposed explosion-proof inert gas replacement process; 4 - Vacuum gradient sublimation camphor removal process; 5 - Directional condensation solid recovery process; 6 - Matrix material reduction sintering process; 7 - Camphor recycling process; 8 - Camphor safe storage process.

Claims

1. A vacuum closed-loop recovery method for recyclable camphor pore-forming agent with an explosion-proof safety mechanism, characterized in that, Includes the following steps: S1 Pre-forming: Camphor pore-forming agent is combined with pore-forming matrix material powder to prepare a blank containing camphor pore-forming agent; S2 Pre-exposed Explosion-proof Replacement: The green blank is placed in a vacuum sintering furnace equipped with a condensation recovery module, an explosion-proof pressure relief unit, and an inert gas inlet unit. After the furnace body is closed, inert gas is introduced to completely replace the air in the furnace cavity, so that the oxygen volume fraction in the furnace cavity is ≤1%. S3 Vacuum Gradient Sublimation Camphor Removal: After the replacement is completed, the vacuum is drawn to the target vacuum level, and the camphor pore-forming agent in the green blank is completely sublimated by gradient heating to form camphor gas. The highest temperature in the furnace does not exceed 200℃ throughout the process, which is far below the auto-ignition temperature of camphor of 466℃. S4 Directional Condensation Solid Recovery: Camphor gas generated by sublimation flows directionally into the furnace body's matching condensation recovery module under vacuum pressure difference. The condensation temperature is set to complete the collection of solid camphor, realizing the closed-loop recovery of the pore-forming agent. S5 Recycling: The solid camphor recovered in step S4 is directly reused in the blank preparation process of step S1, forming a closed-loop recycling.

2. The method according to claim 1, characterized in that, In step S1, the matrix material powder for creating pores is a powder material that can withstand temperatures not lower than 200°C and does not chemically react with camphor, including but not limited to metal powder, ceramic powder, and carbon material powder.

3. The method according to claim 1, characterized in that, In step S1, the camphor pore-forming agent can be used in any one or more combinations of prefabricated three-dimensional interconnected camphor mesh, molten liquid camphor, and large-particle camphor powder.

4. The method according to claim 1, characterized in that, In step S2, the inert gas is nitrogen or argon. After the replacement is completed, the furnace cavity is maintained at a slight positive pressure of 100Pa to 500Pa to prevent outside air from seeping in.

5. The method according to claim 1, characterized in that, In step S3, the process parameters for the vacuum gradient sublimation camphor removal are: vacuum degree ≤100Pa, gradient heating rate ≤5℃ / min, final temperature rise to 120℃~180℃, and holding time 2h~6h, to ensure that the camphor is completely sublimated, without carbonization or residue.

6. The method according to claim 1, characterized in that, In step S4, the set temperature of the condensation recovery module is 0℃~20℃. Camphor gas is condensed in the module to form solid camphor. There is no waste gas emission throughout the process, and the camphor recovery rate is ≥90%.

7. The method according to claim 1, characterized in that, After the vacuum sublimation process in step S3 is completed, there is no need to open the furnace or transfer the green blank. The reduction and sintering processes of the matrix material are completed sequentially in the same vacuum furnace, with inert gas protection maintained throughout the process.

8. The method according to any one of claims 1-7, characterized in that, The storage process for raw camphor and recycled camphor is as follows: use sealed, light-proof containers for storage, maintain an ambient temperature of ≤30℃, ensure good ventilation, keep away from fire sources, heat sources and strong oxidizers, prevent camphor from volatilizing at room temperature and forming explosive vapors, and implement a complete explosion-proof safety mechanism throughout the process.

Images