3D printing sand extraction method and system

Abstract

The invention relates to the technical field of casting material regeneration and resource recycling, in particular to a 3D printing sand extraction method and system. The method comprises the following steps: providing raw material quartz sand covered with an impurity layer on the surface; heating the raw material quartz sand to 750-800 DEG C in an oxygen supply environment, and driving the reaction container to rotate so as to turn over the raw material quartz sand, so that an impurity layer on the surface of the raw material quartz sand is oxidized and removed; and cooling the quartz sand subjected to oxidation removal, so that residual impurities are stripped, and regenerated sand is obtained. Through the heating oxidation and cooling stripping processes, recycling treatment of the 3D printing waste sand is achieved.

Description

Technical Field

[0001] This application relates to the field of casting material recycling and resource recycling technology, and in particular to a method and system for extracting sand from 3D printing. Background Technology

[0002] Currently, the application of 3D printing technology in the precision casting field generates a large amount of coated sand waste. To achieve resource recycling, the industry widely adopts thermal regeneration processes to treat the waste sand. The basic principle of this process is to use a high-temperature environment to carbonize, decompose, and remove the organic resin binder on the surface of the sand particles, thereby restoring the physical and chemical properties of the original sand. Conventional regeneration processes are usually designed as a multi-stage series system, including physical pretreatment before regeneration (such as crushing, screening, or mixing and granulation), core heat treatment (high-temperature calcination), and cooling and dust removal after regeneration.

[0003] However, existing thermal regeneration processes generally suffer from cumbersome processing steps and excessively long process routes. Specifically, these technologies often artificially divide the regeneration process into multiple independent operational units. For example, a separate pretreatment process is often required before heat treatment to adjust the morphology of the waste sand; and during the heat treatment stage, high-temperature roasting and low-temperature utilization are often carried out separately, resulting in the material having to undergo multiple physical transfers between different temperature ranges and equipment. This segmented, multi-stage operation mode not only results in a large number of equipment and a large footprint for the entire production line, but also leads to long material flow paths and easy heat loss at the process junctions due to obvious discontinuities between processes, making it impossible to achieve compact and efficient one-step processing.

[0004] Therefore, the following drawbacks exist: the process flow of 3D printing waste sand recycling methods is lengthy, the operation steps are cumbersome, and the system integration is low. This results in poor continuity of the recycling production line, high energy consumption and control costs, and difficulty in achieving efficient industrial production within a limited space. Summary of the Invention

[0005] To address the technical problems of lengthy and cumbersome processes in the extraction of sand from 3D printing technology, this application provides a method and system for extracting sand from 3D printing.

[0006] The first aspect of this application provides a method for extracting 3D printing sand, employing the following technical solution: A method for extracting 3D printing sand, comprising: S1, providing raw quartz sand, the surface of which is covered with an impurity layer; S2, heating the raw quartz sand in a reaction vessel with an oxygen supply environment, and rotating the reaction vessel to agitate the raw quartz sand, causing the impurity layer on the surface of the raw quartz sand to burn off to obtain clean sand; S3, cooling the clean sand to obtain 3D printing sand.

[0007] By employing the above technical solution, using raw quartz sand covered with an impurity layer as the target material, a comprehensive reaction field with heating, oxygen supply, and rotation is constructed within a single reaction vessel. This allows the impurity layer to burn off, obtaining clean sand, which is then combined with subsequent cooling to ultimately produce 3D printing sand. This method couples heating, mechanical agitation, and oxygen supply within the same space and directly connects the cooling step through heat treatment. It eliminates the need for additional stirring equipment or a separate fluidized bed process, facilitating the consolidation of dispersed operational steps in traditional processes, simplifying the process flow from raw materials to finished products, and shortening the material handling path. This, in turn, helps improve production efficiency and system integration.

[0008] Optionally, in step S1, the raw material quartz sand includes natural quartz sand or coated black sand.

[0009] By adopting the above technical solution, it is clear that this method is applicable to the treatment of coated sand from different sources, especially for coated black sand after 3D printing, which is beneficial to restore its performance through one-step heat treatment.

[0010] Optionally, in step S1, providing the coated black sand includes dry crushing of 3D printed waste sand blocks to obtain the coated black sand.

[0011] By adopting the above technical solution, the waste sand blocks in the initial stage are processed into loose sand, which facilitates subsequent heating and agitation within the reaction vessel, improving the conditions for thermal regeneration. Dry pulverization significantly increases the specific surface area of ​​the waste sand, allowing for more thorough contact between oxygen and the resin film coating the sand particles. Simultaneously, the pulverization process also initially disrupts the sand block structure, helping to reduce the reaction load of subsequent heat treatment. Compared to wet pulverization, dry pulverization also avoids the high-energy-consuming subsequent drying of large quantities of material.

[0012] Optionally, in step S1, providing the coated black sand also includes screening the coated black sand.

[0013] By adopting the above technical solution, impurities that do not meet the particle size requirements are removed through screening, reducing the risk of them entering subsequent heating stages and affecting reaction efficiency, and further improving the smoothness of the process.

[0014] Optionally, in step S2, the heating temperature of the coated black sand is 750 degrees Celsius to 800 degrees Celsius.

[0015] By adopting the above technical solution, resin impurities can be rapidly combusted and decomposed within this temperature range. Combined with rotation and agitation, the material can quickly reach the reaction temperature, shortening the required heating and holding time, thereby indirectly reducing the overall process time. If the temperature is too low, the organic resin may not carbonize completely, easily leading to high residual strength and large gas generation in the recycled sand; if the temperature is too high, it will increase energy consumption and may cause irreversible crystal transformation or sintering of the quartz sand. The 750-800℃ selected in this solution is the optimal process window for balancing reaction efficiency, energy consumption, and sand particle properties, helping to promote the full mineralization of impurities into ash while maintaining the physical properties of the original sand.

[0016] Optionally, in step S2, turning over the coated black sand further includes: causing the coated black sand to be lifted upward along the inner wall of the reaction vessel and then slide downward under the action of gravity.

[0017] By adopting the above technical solution, natural tumbling achieved by physical gravity replaces complex mechanical forced stirring. The sand stream continuously circulates within the container, undergoing lifting and sliding motions, allowing for better heat exchange of the material without a separate mixing process, further simplifying the equipment structure and operating procedures.

[0018] Optionally, in step S2, oxygen is delivered into the material layer formed by the deposit of the coated black sand to provide the oxygen supply environment; the delivery of oxygen is achieved by a gas delivery pipe extending from the end of the reaction vessel, and the gas delivery pipe has multiple branch gas delivery pipes inserted into the material layer of the coated black sand.

[0019] By adopting the above technical solution and using inserted oxygen supply, the slow reaction inside the thick material layer is improved. Traditional processes often require extended roasting time or multiple turning steps to ensure thorough burning. This solution, however, directly introduces oxygen into the material layer, increasing the reaction rate and allowing the impurity layer to burn off in a shorter time, thus helping to shorten the processing cycle for a single batch of material.

[0020] A second aspect of this application provides a 3D printing sand extraction system for performing the method described above, employing the following technical solution: A 3D printing sand extraction system includes a reaction container, a rotary drive, and a heating assembly. The reaction container is used to contain raw material quartz sand and has an oxygen supply environment. The rotary drive is connected to the reaction container and is used to drive the reaction container to rotate. The heating assembly is connected to the reaction container and is used to heat the raw material quartz sand inside the reaction container.

[0021] By adopting the above technical solution, the rotary drive component drives the reaction vessel to rotate, making the vessel itself both a heating site and a turning mechanism. This reduces the need to transfer materials between the heating furnace and the mixer in traditional production lines, and facilitates a high degree of integration of equipment functions.

[0022] Optionally, the reaction vessel is equipped with a lifting plate inside, which is used to lift the raw material quartz sand when the reaction vessel is rotated.

[0023] By adopting the above technical solution, the lifting plate assists in lifting materials within the container, which is beneficial for the materials to achieve sufficient movement and mixing within a single device, reducing the need for manual intervention or additional loosening processes due to material accumulation. The design of the lifting plate also allows the sand to form a more uniform "material curtain" on the container cross-section. This not only increases the contact area between the sand particles and hot air, enhancing the convective heat transfer effect, but also allows the introduced oxygen to pass through the dispersed sand flow more evenly, further improving reaction efficiency.

[0024] Optionally, the 3D printed sand extraction system further includes a gas supply pipe that extends into the interior of the reaction vessel and has multiple branch gas supply pipes that are inserted into the material layer of the raw material quartz sand.

[0025] By adopting the above technical solution, the branch gas supply pipe, as an oxygen supply hardware built into the equipment, directly supplies oxygen to the depth of the material layer as the equipment operates. This structural design reduces the need for repeated roasting due to insufficient oxygen supply, enabling the equipment to achieve higher processing capacity with a more compact structure, which meets the design objectives of simplifying the process and reducing steps.

[0026] In summary, this application includes at least one of the following beneficial technical effects:

[0027] 1. This application achieves one-step thermal regeneration of 3D printed sand by simultaneously heating, agitating, and supplying oxygen within a rotating reaction vessel. Compared to the cumbersome processes of preheating, calcination, and stirring performed in stages in common related technologies, this application integrates multiple processing actions, which helps to reduce process steps and material transfer links, thereby improving production efficiency and equipment integration.

[0028] 2. This application achieves deep oxygen supply by setting branch gas pipes inserted inside the material layer, thereby increasing the oxidation reaction rate. This allows impurities to be removed within a shorter process time, which helps to avoid the need for extended roasting time or additional reheating steps to improve regeneration quality, further shortening the process cycle.

[0029] 3. This application utilizes the lifting and sliding motion generated by the rotation of the reaction vessel, combined with the action of the lifting plates, to achieve uniform heating of the material without adding additional stirring equipment. This passive tumbling method using gravity simplifies the system structure, reduces equipment maintenance costs, and also reduces the risk of downtime due to equipment complexity. Attached Figure Description

[0030] Figure 1 This is a flowchart of the 3D printing sand extraction method according to an embodiment of this application.

[0031] Figure 2 This is a top view of the 3D printing sand extraction system according to an embodiment of this application.

[0032] Figure 3 This is a schematic diagram of the structure of the 3D printing sand extraction system according to an embodiment of this application. Figure 1 It is mainly used to display structures such as feeding devices.

[0033] Figure 4 This is a schematic diagram of the structure of the 3D printing sand extraction system according to an embodiment of this application. Figure 2 It is mainly used to demonstrate structures such as material discharge devices.

[0034] Explanation of reference numerals in the attached figures:

[0035] 10. Reaction vessel; 11. Lifting plate; 12. Inlet / outlet;

[0036] 20. Rotary drive component; 21. Shaft; 22. Motor;

[0037] 30. Heating components;

[0038] 40. Gas supply pipe; 41. Branch gas supply pipe; 42. Air inlet;

[0039] 50. Dust removal device;

[0040] 60. Sprinkler system;

[0041] 70. Cubic meter silo; 71. Feeding device;

[0042] 80. Finished product warehouse; 81. Discharge device. Detailed Implementation

[0043] The following is in conjunction with the appendix Figure 1-4 This application will be described in further detail.

[0044] This application relates to a method for extracting sand from 3D printing, as described in the embodiments below. Figure 1 The 3D printing sand extraction method mainly includes the following steps:

[0045] S1. Provide raw material quartz sand, the surface of which is covered with an impurity layer.

[0046] In this embodiment, the source of the raw material quartz sand is widely adaptable, including both coated black sand produced after 3D printing casting and ordinary natural quartz sand (such as river sand, sea sand, desert sand, or mineral sand). For coated black sand, its surface is covered with curing agent, resin, and ignition residue from the cross-linking reaction. This type of waste sand usually exists in the form of large sand lumps; therefore, in step S1, a grinding action is first performed. For example, a dedicated sand crusher is used to finely crush the waste sand lumps, restoring them to a loose sand state with a particle size of 50 to 200 mesh. During the crushing process, the crushing intensity is controlled primarily to disintegrate the sand lumps, minimizing damage to the original crystal structure of the quartz sand. Furthermore, the grinding equipment can be equipped with a structure with wear-resistant liners, such as high-manganese steel or ceramic liners, to meet the needs of long-term operation. Subsequently, screening is performed to remove metal residues or large, uncrushed impurities mixed in during the casting process; at this point, the sand particles are still black. The screening process typically employs vibrating screens or drum screens, with the screen mesh size matching the particle size range required for 3D printing sand preparation. This ensures that the material entering the subsequent heat treatment stage has a relatively uniform particle size, which is beneficial for uniform heating. While natural quartz sand has not undergone printing, its surface is often covered with various organic impurities, resulting in excessively high acid consumption values ​​that cannot directly meet the resin curing requirements in 3D printing. The natural quartz sand provided in this step is also used as a raw material to be treated, with the aim of removing its surface organic impurities in subsequent steps.

[0047] S2. The raw material quartz sand is heated in a reaction vessel with an oxygen supply environment, and the reaction vessel is rotated to agitate the raw material quartz sand, causing the impurity layer on the surface of the raw material quartz sand to burn off and obtain clean sand. The prepared raw material quartz sand is fed into the reaction vessel 10. This step adopts an intermittent processing logic, that is, batch feeding and discharging. A quantitative feeding method can be used during feeding to ensure that the processing volume of each batch is within the optimal load range of the equipment, which helps to maintain stable thermal conditions. Before formal heating, a short period of low-speed rotation can be performed to make the material evenly distributed in the container. Start heating to raise and maintain the temperature in the reaction vessel between 750 degrees Celsius and 800 degrees Celsius. In the initial stage of heating, the heating rate can be appropriately accelerated to allow the sand particles to quickly pass through the low-temperature zone, thereby shortening the time that the resin is in a viscous state and avoiding the resin only softening without decomposition at low temperatures, which would cause the sand particles to stick together.

[0048] When the temperature reaches the target range, the organic binder undergoes a vigorous redox reaction, breaking carbon chains and generating carbon dioxide and water vapor which are then released. Specifically, for coated black sand, since the resin film on its surface is essentially a high-calorific-value hydrocarbon, it produces a violent exothermic reaction upon being added to the reaction vessel and ignited, releasing a large amount of heat. This system fully utilizes this characteristic to reuse the energy from combustion regeneration: during the most intense stage of the black sand combustion reaction, the chemical energy released can serve as a supplementary heat source. At this time, the temperature control system senses the rising trend of the furnace temperature and automatically reduces or temporarily shuts off the electrical output of the heating element 30, relying on the heat generated by the combustion of the resin on the sand grain surface to maintain the high temperature of the furnace. This significantly reduces the system's external energy consumption while ensuring the regeneration effect. This temperature range also helps reduce the generation of harmful byproducts such as nitrogen oxides. For coated black sand, combustion treatment is maintained at this high temperature for at least 20 minutes until the black resin layer and impurities on the sand grain surface are completely burned off, transforming the black sand into white sand. In the later stages of the reaction, the carbon dioxide concentration in the exhaust gas can be monitored through an observation window or an online gas analyzer. When the concentration decreases significantly and tends to stabilize, the reaction endpoint can be determined, thus avoiding overburning and wasting energy. For natural quartz sand, since its impurities are mainly surface organic matter, the combustion time can be shortened to 5 to 10 minutes, which can effectively remove impurities and reduce acid consumption.

[0049] During heating, the reaction vessel rotates continuously. Preferably, the reaction vessel adopts a spindle-shaped inner liner structure, coupled with lifting plates on the inner wall. As the vessel rotates, the sand particles are repeatedly lifted and tumbled, forming a uniform heated flow. This spindle-shaped design facilitates the natural convergence of materials towards the center of the vessel under gravity, avoiding material accumulation in the dead corners at both ends and improving the space utilization of the vessel. Simultaneously, a blower, in conjunction with branching gas pipes extending deep into the vessel, continuously supplies oxygen to the tumbling material layer. The outlets of the branching gas pipes can be designed with a certain angle or employ anti-clogging structures, such as the outlets facing away from the direction of sand flow to prevent sand particles from backflowing and clogging the outlets. In addition, flow meters and regulating valves can be installed on the gas pipeline to automatically adjust the oxygen supply according to different reaction stages, such as increasing the flow rate during vigorous reaction periods to replenish consumption and decreasing the flow rate at the end of the reaction to save power consumption. At the same time, the ejected airflow also provides a certain degree of pneumatic stirring for the surrounding sand particles, further enhancing the mass transfer effect. Under the combined effects of high temperature, rich oxygen, and mechanical agitation, the impurity layer on the surface of the raw material undergoes a violent oxidation reaction and is burned off.

[0050] S3. Cool the clean sand to obtain 3D printing sand. After combustion, the high-temperature clean sand is discharged by controlling the reverse of the reaction vessel and then cooled. Cooling can be done naturally or by water cooling to bring it to room temperature. It is worth noting that during the cooling process, the high-temperature silica sand undergoes an alpha (α) phase transition naturally when it passes through a temperature range of approximately 570 degrees Celsius. This phase transition is accompanied by a volume expansion of about 0.82%. This physical change helps to further disintegrate and peel off residual trace resin films or inorganic impurities. The specific mechanism is that the quartz sand matrix and the residual impurity layer on the surface (such as inorganic salts or residual carbon ash) have different coefficients of thermal expansion. At the moment of the phase transition, the matrix undergoes a sudden expansion, while the surface layer expands less, generating huge shear stress at the interface. This helps to mechanically "break off" and peel off the loosely attached ash, revealing the original clean surface of the sand particles. Furthermore, the recycled sand, after undergoing this phase transformation and expansion, exhibits a significantly reduced shrinkage and expansion rate when heated and subsequently used for casting mold making, thus facilitating more precise control over casting accuracy. Finally, the cooled sand particles can be further separated into recycled sands of different particle sizes through a screening device to meet the needs of various casting processes.

[0051] The implementation principle of the 3D printing sand extraction method in this application embodiment is as follows: This method utilizes the high-temperature thermal regeneration principle, compatible with the processing of industrial waste black sand and low-quality natural sand. By crushing the material to a specific mesh size (e.g., 50-200 mesh), and in a high-temperature rotating environment of 750-800℃, combined with dendritic deep oxygen supply, surface organic impurities are efficiently burned off. In particular, by utilizing the volume expansion characteristics of crystal phase transition during the cooling stage, the cleanliness and dimensional stability of the sand particles are further improved, solving the environmental pollution problem of waste sand, while reducing the cost of obtaining high-quality 3D printing sand.

[0052] This application also relates to a 3D printing sand extraction system.

[0053] Reference Figure 2 The system is designed as a mobile, intermittent production line for an electrically heated rotary kiln. The 3D printing sand extraction system mainly includes: a reaction vessel 10, a rotary drive component 20, a heating assembly 30, a gas supply pipe 40, a cubic silo 70, and a finished product silo 80.

[0054] Reference Figure 2 and Figure 3The system is configured with components sequentially along the material flow direction. The cubic silo 70 is used to temporarily store raw quartz sand that has undergone crushing and screening, with the particle size of the raw quartz sand ranging from 50 mesh to 200 mesh. A feeding device 71, such as a screw conveyor, is connected to the cubic silo 70. The output end of the feeding device 71 extends to the inlet / outlet 12 of the reaction vessel 10, and is used to transport the raw quartz sand into the interior of the reaction vessel 10.

[0055] The inner liner of the reaction vessel 10 is made of stainless steel and has an overall spindle-shaped structure, wrapped with insulation material. The insulation material is typically made of low thermal conductivity materials such as ceramic fiber cotton or lightweight refractory bricks, and a multi-layer composite insulation structure can be used to reduce heat loss to the environment, improve thermal efficiency, and prevent burns to operators. The stainless steel inner liner can be made of heat-resistant steel to resist high-temperature oxidation and abrasion from sand particles. The reaction vessel 10 has inlet and outlet ports 12, which serve as shared ports for both the inlet and outlet channels. Multiple lifting plates 11 are arranged circumferentially on the inner wall of the reaction vessel 10 to lift and scatter the internal material during rotation.

[0056] The rotary drive component 20 is mechanically connected to the reaction vessel 10 and is used to drive the reaction vessel 10 to rotate around its axis. The rotary drive component 20 may include a motor, a reducer, and transmission gears, wherein the motor is preferably a variable frequency motor so as to adjust the rotation speed of the reaction vessel according to process requirements, for example, rotating at a low speed during the heating stage and increasing the rotation speed to enhance agitation during the isothermal reaction stage. The rotary drive component 20 is configured with forward and reverse rotation control logic: during the feeding and heating reaction stages, it drives the reaction vessel 10 to rotate forward, cooperating with the lifting plate 11 to agitate the material; during the discharging stage, it drives the reaction vessel 10 to rotate in the reverse direction, using the guiding action of the spindle-shaped inner liner and the reverse pushing action of the lifting plate 11 to guide the material to the inlet / outlet 12. This forward and reverse discharge logic eliminates the need for a complex unloading valve mechanism, avoids the failure point of valve jamming or sealing failure at high temperatures, and improves the operational reliability of the system.

[0057] The heating component 30, using electric heating, is located outside the reaction vessel 10 and provides a reaction temperature of 750°C to 800°C. The heating component can use resistance wire or silicon carbide rods as heating elements, arranged in sections outside the reaction vessel. A PID temperature control system precisely controls the temperature of each section to ensure a uniform temperature field inside the vessel. Compared to gas heating, electric heating is easier to automate and precisely control the temperature, and there are no combustion exhaust emissions, making it more environmentally friendly. The gas supply pipe 40 has an air inlet 42 for connecting to an external gas supply device, such as a blower. The other end of the gas supply pipe 40 extends through the inlet / outlet 12 into the interior of the reaction vessel 10, and multiple branch gas supply pipes 41 are provided on the extension section. The gas supply pipe 40 and the branch gas supply pipes 41 have a tree-like, branched structure. The openings of the branch gas supply pipes 41 are inserted into the material layer inside the reaction vessel 10 to achieve deep gas supply.

[0058] Reference Figure 2 and Figure 4 A discharge device 81 is also provided at the inlet / outlet 12 of the reaction vessel 10. The input end of the discharge device 81 is located below or to the side of the inlet / outlet 12, and is used to receive the high-temperature sand discharged from the reaction vessel 10 in reverse. Its output end is connected to the finished product silo 80. The material is cooled during the conveying process of the discharge device 81 or in the finished product silo 80, and impurities are further removed by utilizing the aforementioned alpha phase change expansion characteristics. In addition, the system is also equipped with a dust removal device 50 and a spray device 60. The dust removal device 50 is connected to the reaction vessel 10 through a pipeline and is used to suck up the dust generated by the reaction; the spray device 60 is connected to the rear end of the dust removal device 50 and is used to spray and wash the exhaust gas. At the same time, an alkaline absorbent can be added to the spray device 60 to neutralize any small amount of acidic components that may be present in the exhaust gas, ensuring that the final exhaust gas meets national and local environmental protection standards.

[0059] The implementation principle of the 3D printing sand extraction system in this embodiment is as follows: The system adopts an intermittent working mode. First, the pre-treated raw material is fed into the spindle-shaped reaction vessel 10 through the feeding device 71. The rotary drive 20 drives the vessel to rotate forward, the heating component 30 provides a high-temperature environment, and the external gas supply device supplies oxygen to the tumbling sand layer through the tree-shaped gas pipe 40, causing the organic impurities on the surface of the sand particles to burn. After the reaction is completed, the vessel is reversed, and the high-temperature sand is discharged into the finished product silo 80 through the inlet / outlet 12, and then cooled and phase-change treated to obtain regenerated sand. The waste gas in the production process is purified by the dust removal device 50 and the spray device 60 before being discharged.

[0060] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A method for extracting sand from 3D printing, characterized in that, include: S1. Provide raw material quartz sand, the surface of which is covered with an impurity layer; S2. The raw material quartz sand is heated in a reaction vessel (10) with an oxygen supply environment, and the reaction vessel (10) is rotated to agitate the raw material quartz sand, so that the impurity layer on the surface of the raw material quartz sand is burned to obtain clean sand. S3. Cool the clean sand to obtain 3D printing sand.

2. The 3D printing sand extraction method according to claim 1, characterized in that, In step S1, the raw material quartz sand includes natural quartz sand or coated black sand.

3. The 3D printing sand extraction method according to claim 2, characterized in that, In step S1, providing the coated black sand includes dry crushing of 3D printed waste sand blocks to obtain the coated black sand.

4. The 3D printing sand extraction method according to claim 3, characterized in that, In step S1, providing coated black sand also includes screening the coated black sand.

5. The 3D printing sand extraction method according to claim 2, characterized in that, In step S2, the heating temperature of the coated black sand is 750 degrees Celsius to 800 degrees Celsius.

6. The 3D printing sand extraction method according to claim 2, characterized in that, In step S2, turning the coated black sand further includes: lifting the coated black sand upward along the inner wall of the reaction vessel (10) and letting it slide downward under the influence of gravity.

7. The 3D printing sand extraction method according to claim 2, characterized in that, In step S2, oxygen is delivered into the interior of the raw material quartz sand layer to provide the oxygen-supplying environment.

8. A 3D printing sand extraction system for performing the method as described in any one of claims 1 to 7, characterized in that, include: The reaction vessel (10) is used to contain the raw material quartz sand and has an oxygen supply environment; A rotary drive (20) is connected to the reaction vessel (10) and is used to drive the reaction vessel (10) to rotate; A heating component (30) is connected to the reaction vessel (10) and is used to heat the raw material quartz sand inside the reaction vessel (10).

9. The 3D printing sand extraction system according to claim 8, characterized in that, The reaction vessel (10) is equipped with a lifting plate (11) inside, which is used to lift the raw material quartz sand when the reaction vessel (10) rotates.

10. The 3D printing sand extraction system according to claim 8, characterized in that, It also includes a gas delivery pipe (40) that extends into the interior of the reaction vessel (10) and has multiple branch gas delivery pipes (41) that are inserted into the material layer of the raw material quartz sand.

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