A low-temperature extrusion preparation device and preparation process of a calcium carbonate filled master batch

Abstract

The application relates to the technical field of calcium carbonate filling master batch preparation, and discloses a low-temperature extrusion preparation device and preparation process of calcium carbonate filling master batch, which comprises a double-screw extruder and a water tank installed to the outer side of the double-screw extruder; one side of the water tank is fixedly provided with a water inlet pipe and a backflow pipe which are in communication with the water tank; the outer side of the backflow pipe is fixedly connected with a converging pipe which is in communication with the backflow pipe; a gas guide member is arranged in the backflow pipe and used for circulatingly conveying gas; and a spiral blade is rotationally connected to the inside of the backflow pipe. The water can be pre-cooled, the heat dissipation burden of the water tank is reduced, the cooling circulation efficiency is guaranteed, the water source flow can be assisted during the water source backflow process, the cold-hot water mixing efficiency is improved, the subsequent cooling effect is guaranteed, the cooling intensity can be flexibly adjusted according to the load of the double-screw extruder during use, the problems of insufficient cooling and excessive cooling are reduced, and the extrusion effect is guaranteed.

Description

Technical Field

[0001] This invention relates to the field of calcium carbonate filler masterbatch preparation technology, specifically to a low-temperature extrusion preparation device and process for calcium carbonate filler masterbatch. Background Technology

[0002] Calcium carbonate filler masterbatch is a functional additive made by mixing, extruding and granulating calcium carbonate powder as the main filler, polyolefin resin as the carrier and adding a variety of additives. Due to the wide availability and low price of calcium carbonate, calcium carbonate filler masterbatch is widely used in the production of plastic products, which can significantly reduce raw material costs and improve the rigidity and dimensional stability of products.

[0003] In the preparation of calcium carbonate filler masterbatch, the twin-screw extruder is the core equipment. During operation, the barrel and screw generate a large amount of heat due to the shear friction of the material. To achieve low-temperature extrusion, existing technologies typically install a cooling device on the barrel of the extruder. The excess heat is removed by the circulation of the cooling medium in the barrel's water channels. This is achieved by using a water tank, water pump, inlet pipe, and return pipe, along with multiple inlet and return pipe connections. However, this method has the following drawbacks in actual use: the return water temperature is high, the water tank has a heavy heat dissipation burden, which can easily affect the cooling circulation efficiency. Furthermore, after the water source returns, the hot and cold water in the water tank is prone to uneven mixing, leading to a decrease in subsequent cooling effect. During use, the cooling capacity is fixed, making it difficult to flexibly adjust the cooling intensity according to the actual load of the extruder, which can easily cause over-cooling or under-cooling, affecting the extrusion effect. Summary of the Invention

[0004] The purpose of this invention is to provide a low-temperature extrusion preparation apparatus and process for calcium carbonate filler masterbatch, so as to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a low-temperature extrusion preparation device for calcium carbonate filler masterbatch, comprising a twin-screw extruder and a water tank installed on its outer side, wherein a water inlet pipe and a return pipe are fixedly installed on one side of the water tank and communicate with it, and a flow-gathering pipe is fixedly connected to the outer side of the return pipe and communicates with it; a gas guide component is disposed inside the return pipe for circulating gas transport; a spiral blade is rotatably connected to the inside of the return pipe; and a mixing component is disposed inside the water tank, wherein the mixing component includes two mesh covers and a slider, the bottom mesh cover being rotatable along its own axis, the slider being fixedly connected to the top of the bottom mesh cover, and one side of the slider being slidably connected to the inside of the top mesh cover.

[0006] Preferably, the air guide includes an annular pipe disposed inside the water tank; multiple branch pipes arranged in a ring, one end of which is connected to the annular pipe and the other end extends into the interior of the return pipe; and two exhaust pipes, which are positioned horizontally above the axis of the return pipe, with the end of the exhaust pipe located on the side of the spiral blade away from the water tank.

[0007] Preferably, the return pipe has an internal cavity, and the branch pipe and the exhaust pipe are both connected to the cavity at the ends away from the water tank. A solenoid valve is installed on the outside of the exhaust pipe.

[0008] Preferably, the return pipe is fixedly connected to the end of the water tank with a connecting pipe, the top mesh cover is fixedly installed inside the connecting pipe, and the bottom mesh cover is rotatably connected to the inside of the connecting pipe.

[0009] Preferably, a rotating shaft is fixedly inserted inside the spiral blade, and supports sleeved to the outside of the rotating shaft are fixedly connected inside both the return pipe and the connecting pipe.

[0010] Preferably, a scraper is fixedly connected to the outer side of the rotating shaft, and a vertical rod is fixedly connected to the bottom of the bottom mesh cover, with the vertical rod positioned on the movement path of the scraper.

[0011] Preferably, an arc-shaped plate is fixedly connected between two adjacent branch pipes, and the arc-shaped plate is embedded inside the return pipe.

[0012] Preferably, an air pump is fixedly installed on the outside of the water tank, and both the output and input ends of the air pump are fixedly connected to a bend pipe. One end of the bend pipe is inserted into and fixedly connected to the inside of the water tank, and one end of the bottom bend pipe communicates with the inside of the annular pipe.

[0013] Preferably, elastic ropes are fixedly connected to both sides of the slider, and the end of the elastic rope away from the slider is fixedly connected to the inside of the top mesh cover.

[0014] This invention also provides a low-temperature extrusion preparation process for calcium carbonate filler masterbatch, comprising the following steps: 1. Melt mixing: The premixed material is fed into the twin-screw extruder through the feeding system. Under the forced conveying and shearing action of the screw, the material is gradually melted and plasticized. The calcium carbonate powder is uniformly dispersed in the carrier resin to form a molten mixture. 2. Cooling water circulation for cooling: Cooling water circulation is started simultaneously during the melting and mixing process. The water pump draws out the low-temperature water source in the water tank, transports it along the water inlet pipe and enters the barrel water channel of the twin-screw extruder through the water inlet connection pipe to cool the barrel and screw. The water source that has absorbed heat becomes high-temperature return water, flows into the convergence pipe through the return connection pipe and then flows back to the water tank along the return pipe to form continuous water circulation cooling, so that the barrel temperature is controlled within the preset low-temperature extrusion range. 3. Low-temperature gas pre-cooling: The air pump is started to extract the low-temperature gas from the top of the water tank and transport it to the ring pipe through the bend pipe. When the gas flows through the ring pipe and the branch pipe, it is further cooled by the low-temperature water source in the water tank. Then it enters the cavity of the thick wall of the return pipe to cool the pipe wall. Then it is sprayed into the inside of the return pipe through the exhaust pipe to contact the high-temperature return water for heat exchange, thus pre-cooling the return water source. IV. Gas-liquid mixing and spiral blade drive: The gas ejected from the exhaust pipe drives the spiral blades inside the return pipe to rotate. The rotating spiral blades disrupt the laminar boundary layer of the return water flow and agitate the gas and liquid to fully mix and enhance heat exchange. On the other hand, they continuously flush the inner wall of the return pipe to reduce dirt accumulation. 5. The staggered adjustment of the mesh cover regulates the mixing of air bubbles with the water tank. The rotating spiral blades drive the rotating shaft to rotate. The scraper on the rotating shaft repeatedly hits the vertical rod on the bottom mesh cover, causing the bottom mesh cover to rotate around the shaft. The degree of stagger between the bottom mesh cover and the top mesh cover continuously changes, so that when the gas-liquid mixture is discharged into the water tank through the mesh cover holes, it forms air bubbles of different sizes. When the degree of stagger is small, the air bubbles are large and surge strongly. When the degree of stagger is large, the air bubbles are small and evenly distributed, which helps to fully mix the original cold water and the return water source in the water tank. VI. Gas recycling and cooling intensity adjustment: After the gas is discharged from the mesh cover into the water tank, it rises to the inner top wall and is drawn back into the tank by the air pump for recycling. Adjusting the opening of the solenoid valve on the outside of the exhaust pipe changes the amount of gas jet, thereby simultaneously changing the speed of the spiral blades, the frequency of mesh cover crossing, and the mixing intensity of the water tank, so as to achieve on-demand control of cooling intensity. 7. Extrusion granulation: After thorough mixing and temperature control, the molten material is extruded into strips from the die of a twin-screw extruder. The strips are then pelletized, cooled, and dried to obtain the finished calcium carbonate filler masterbatch. Compared with the prior art, the beneficial effects of the present invention are as follows: This invention introduces low-temperature gas from the water tank into the return pipe through a ring pipe, branch pipe, and exhaust pipe, allowing it to directly contact and exchange heat with the high-temperature return water. This pre-cools the return water source, effectively reducing the temperature of the return water entering the water tank, alleviating the cooling load on the water tank, and significantly improving the overall cooling efficiency of the circulating cooling system. At the same time, the gas ejected from the exhaust pipe drives the spiral blades inside the return pipe to rotate, which not only enhances the gas-liquid mixing heat exchange effect but also continuously flushes the inner wall of the return pipe, reducing the accumulation of dirt on the inner wall of the pipe.

[0015] By setting up a mixing component consisting of two mesh covers and a slider, the bottom mesh cover continuously reciprocates relative to the top mesh cover, thereby continuously changing the degree of overlap of the through holes between the two mesh covers. This causes the gas-liquid mixture to form bubbles of different sizes when it enters the water tank, thus achieving rapid mixing of cold water and return water in the water tank. This effectively avoids the phenomenon of hot and cold stratification and ensures stable circulating water temperature and subsequent cooling effect.

[0016] By installing a solenoid valve on the exhaust pipe to control the jet volume, a single adjustment action can simultaneously change the cooling effect of three paths: the pre-cooling intensity of the return water, the stirring intensity of the spiral blades, and the mixing intensity of hot and cold water in the water tank. This controls the low temperature of the water source in the water tank and achieves flexible adjustment of the cooling capacity. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of a preferred embodiment of the low-temperature extrusion preparation apparatus and preparation process for calcium carbonate filler masterbatch provided by the present invention. Figure 2 This is a schematic diagram of the twin-screw extruder and water tank provided by the present invention; Figure 3 for Figure 2 Enlarged view of A in the middle; Figure 4 This is a schematic diagram of the structure of the water tank and the water inlet pipe provided by the present invention; Figure 5 This is a schematic diagram of the structure of the return pipe and the connecting pipe provided by the present invention; Figure 6 A partial structural diagram of the reflux pipe and branch pipe provided by the present invention; Figure 7 This is a cross-sectional schematic diagram of the flow-collecting tube and the connecting tube provided by the present invention; Figure 8 for Figure 7 Enlarged view of B in the middle; Figure 9 An exploded view of the bottom mesh cover and slider provided by the present invention; Figure 10 This is a cross-sectional schematic diagram of the reflux pipe provided by the present invention.

[0018] In the diagram: 100, twin-screw extruder; 110, water inlet pipe; 120, return pipe; 121, cavity; 122, connecting pipe; 130, converging pipe; 200, water tank; 210, air pump; 220, folded pipe; 300, air guide; 310, annular pipe; 320, branch pipe; 321, arc plate; 330, exhaust pipe; 331, solenoid valve; 400, spiral blade; 410, rotating shaft; 411, scraper; 500, mixing component; 510, mesh cover; 511, vertical rod; 520, slider; 521, elastic rope. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Please see Figures 1-10 As shown, a low-temperature extrusion preparation apparatus for calcium carbonate filler masterbatch includes: The twin-screw extruder 100 is connected to a water tank 200 mounted on its outside. A water inlet pipe 110 and a return pipe 120 are fixedly installed on one side of the water tank 200 and communicate with it. A flow-gathering pipe 130 is fixedly connected to the outside of the return pipe 120 and communicates with it. A gas guide 300 is disposed inside the return pipe 120 and is used to circulate and transport gas. A spiral blade 400 is rotatably connected to the inside of the return pipe 120. A mixing component 500 is disposed inside the water tank 200. The mixing component 500 includes two screens 510 and a slider 520. The bottom screen 510 can rotate along its own axis. The slider 520 is fixedly connected to the top of the bottom screen 510. One side of the slider 520 is slidably connected to the inside of the top screen 510.

[0021] When the material is fed into the twin-screw extruder 100 for extrusion, cooling can be performed simultaneously. After cooling, the low-temperature water in the water tank 200 is introduced through the inlet pipe 110 and then enters the barrel water channel of the twin-screw extruder 100 for further cooling. The low-temperature water then flows back to the water tank 200 through the convergence pipe 130 and return pipe 120, circulating gradually. During this circulating water cooling process, the low-temperature water in the water tank 200 lowers the gas temperature. The low-temperature gas is then transported to the inside of the return water pipe using the gas guide 300 to pre-cool the return water, reducing the subsequent cooling intensity of the water in the water tank 200. During the flow process, the spiral blades 400 move in response to the impact of the return water source. On the one hand, this disrupts laminar flow, improves the contact effect with the pipe wall, and makes the gas-liquid mixture more complete, thus improving the heat exchange effect and reducing the accumulation of dirt inside the pipe. On the other hand, it drives the bottom mesh cover 510 to slide, so that the two mesh covers 510 change from an overlapping state to an interlaced state. After the gas is discharged into the water tank 200, bubbles of corresponding sizes and water flow resistance are formed according to the degree of interlacing of the two mesh covers 510. This improves the rapid mixing of the original cold water and the return water source in the water tank 200, which facilitates the subsequent cooling speed of the water source in the water tank 200 and reduces the occurrence of uneven heating and cooling.

[0022] It should be noted that the water tank 200 in this application may be equipped with multiple-point coolers (not shown in the figure) on the side or bottom, which is an existing refrigeration technology. The cooler can be a semiconductor cooler or other corresponding type of cooler, and the specific selection can be determined according to the actual use requirements.

[0023] A set of inlet water connection pipe and return flow connection pipe are installed at the bottom of the twin-screw extruder 100. A flow control valve is fixedly installed on the outside of the inlet water connection pipe. One end of the inlet water connection pipe is connected to the inlet water pipe 110, and one end of the return flow connection pipe is connected to the flow convergence pipe 130.

[0024] A water pump is fixedly installed on one side of the water tank 200 and is installed on the inlet pipe 110 to draw water from the water tank 200 into the inlet pipe 110.

[0025] The air guide 300 includes an annular pipe 310, which is disposed inside the water tank 200; multiple branch pipes 320, which are arranged in a ring, with one end connected to the annular pipe 310 and the other end extending into the interior of the return pipe 120; two exhaust pipes 330, which are positioned horizontally above the axis of the return pipe 120, with the end of the exhaust pipe 330 located on the side of the spiral blade 400 away from the water tank 200; a cavity 121 is opened inside the return pipe 120, and the ends of the branch pipes 320 and the exhaust pipes 330 away from the water tank 200 are connected to the cavity 121; a solenoid valve 331 is installed on the outside of the exhaust pipe 330.

[0026] Both the annular pipe 310 and the branch pipe 320 are located below the water level line in the water tank 200. The gas inside is affected by the low temperature water source, causing its temperature to drop. The gas is then introduced into the wall of the return pipe 120 to reduce the temperature of the return pipe 120 itself. After contacting the return water source, it can be pre-cooled. The used gas enters the cavity 121 and is then discharged along the exhaust pipe 330 into the return pipe 120. On the one hand, the gas is recycled, which is more energy-efficient and reduces the difficulty of gas cooling. On the other hand, the discharged gas can be used to drive the spiral blades 400, reducing the mixing effect of water and gas and further cooling. The solenoid valve 331 can be used to adjust the amount of gas ejected from the air exhaust pipe 330, thereby changing the rotation speed of the spiral blades 400. This can correspondingly change the frequency of the staggered movement of the two screens 510, changing the mixing effect of the low temperature water source and the return water source in the water tank 200 and controlling the subsequent cooling intensity.

[0027] It should be noted that there are two exhaust pipes 330, which can effectively cover the area where the spiral blades 400 are located, ensuring that the exhaust gas has an effective impact on the spiral blades 400.

[0028] The return pipe 120 is fixedly connected to the end of the water tank 200 with a connecting pipe 122. The top mesh cover 510 is fixedly installed inside the connecting pipe 122, and the bottom mesh cover 510 is rotatably connected to the inside of the connecting pipe 122.

[0029] Water and gas in the return pipe 120 can enter the connecting pipe 122 and then be discharged through the holes in the mesh cover 510.

[0030] The specifications, quantity, and internal hole shape of the 510 mesh cover can be selected according to actual usage requirements.

[0031] The spiral blade 400 has a rotating shaft 410 fixedly running through it. The return pipe 120 and the connecting pipe 122 are both fixedly connected to supports that are sleeved to the outside of the rotating shaft 410. The outside of the rotating shaft 410 is fixedly connected to a scraper 411. The bottom of the bottom mesh cover 510 is fixedly connected to a vertical rod 511, which is located on the movement path of the scraper 411. Both sides of the slider 520 are fixedly connected to elastic ropes 521, and the end of the elastic rope 521 away from the slider 520 is fixedly connected to the inside of the top mesh cover 510.

[0032] When the spiral blade 400 rotates, the shaft 410 is driven accordingly, causing the scraper 411 to rotate as well. During the rotation of the scraper 411, it can repeatedly strike the vertical rod 511, causing the vertical rod 511 to drive the bottom mesh cover 510 to rotate to a corresponding degree. Then, the sliding is pulled back to its original position by the corresponding elastic rope 521. Then, the bottom mesh cover 510 is pressed and moves here, repeating the cycle, thereby continuously changing the staggered situation between the two mesh covers 510.

[0033] It should be noted that the support has a bearing sleeved on the outside of the rotating shaft 410, and the connection between the bearing and the support is provided with a corresponding number of sealing rings.

[0034] When the two mesh covers 510 overlap, the effective discharge area is large, the water flow resistance is reduced, and the bubble size is large, resulting in strong turbulence of the discharged water and air, thus improving the mixing effect. When they partially overlap, the water flow resistance increases, the bubble size becomes smaller, but the number of channels increases, forming a multi-point turbulence area, which further improves the mixing effect. That is, when the rotation speed of the shaft 410 is low, the circulation efficiency of the two mesh covers 510 is low, and the overall mixing effect is lower than when the rotation speed of the shaft 410 is high. Adjusting the opening of the solenoid valve 331 changes the gas-liquid mixing ratio and the stirring frequency of the spiral blades 400, thereby obtaining the best cooling and heat exchange efficiency that matches the current extrusion load.

[0035] An arc-shaped plate 321 is fixedly connected between each two adjacent branch pipes 320, and the arc-shaped plate 321 is embedded inside the return pipe 120.

[0036] By using the arc-shaped plate 321, the cooling range of the return pipe 120 itself can be further increased, making the cooling area affected by low-temperature gas larger and more uniform, thus improving the cooling effect on the return water source.

[0037] It should be noted that the arc plate 321, the annular pipe 310, and the branch pipe 320 are all made of copper to ensure effective temperature transfer.

[0038] An air pump 210 is fixedly installed on the outside of the water tank 200. Both the output and input ends of the air pump 210 are fixedly connected to a bend pipe 220. One end of the bend pipe 220 is inserted into and fixedly connected to the inside of the water tank 200. One end of the bottom bend pipe 220 is connected to the inside of the annular pipe 310.

[0039] Starting the air pump 210 allows the gas inside the water tank 200 to be introduced into the annular pipe 310 along the bend pipe 220 for subsequent recycling.

[0040] It should be noted that the height of the top bend 220 is higher than the water level line inside the water tank 200.

[0041] This invention also provides a low-temperature extrusion preparation process for calcium carbonate filler masterbatch, comprising the following steps: 1. Melt mixing: The premixed material is fed into the twin-screw extruder 100 through the feeding system. Under the forced conveying and shearing mixing action of the screw, the material is gradually melted and plasticized. The calcium carbonate powder is uniformly dispersed in the carrier resin to form a molten mixture. 2. Cooling water circulation for cooling: Cooling water circulation is started simultaneously during the melting and mixing process. The water pump draws out the low-temperature water source in the water tank 200, transports it along the water inlet pipe 110 and enters the barrel water channel of the twin-screw extruder 100 through the water inlet connecting pipe, and cools the barrel and screw. The water source that has absorbed heat becomes high-temperature return water, flows into the convergence pipe 130 through the return connection pipe, and then flows back to the water tank 200 along the return pipe 120, forming continuous water circulation cooling, so that the barrel temperature is controlled within the preset low-temperature extrusion range. 3. Low-temperature gas pre-cooling: The gas pump 210 is started to extract the low-temperature gas from the top of the water tank 200 and transport it to the ring pipe 310 along the bend pipe 220. When the gas flows through the ring pipe 310 and the branch pipe 320, it is further cooled by the low-temperature water source in the water tank 200. Then it enters the cavity 121 of the return pipe 120 to cool the pipe wall. Then it is sprayed into the return pipe 120 through the exhaust pipe 330 to contact the high-temperature return water for heat exchange, thus pre-cooling the return water source. IV. Gas-liquid mixing and spiral blade 400 drive: The gas ejected from the exhaust pipe 330 drives the spiral blade 400 inside the return pipe 120 to rotate. The rotating spiral blade 400 disrupts the laminar boundary layer of the return water flow and agitates the gas and liquid to mix fully and enhance heat exchange. On the other hand, it continuously flushes the inner wall of the return pipe 120 and reduces dirt accumulation. 5. The mesh cover 510 adjusts the mixing of air bubbles with the water tank 200. The rotating spiral blade 400 drives the rotating shaft 410 to rotate. The scraper 411 on the rotating shaft 410 repeatedly hits the vertical rod 511 on the bottom mesh cover 510, causing the bottom mesh cover 510 to rotate around the shaft. The bottom mesh cover 510 continuously changes the degree of overlap with the top mesh cover 510, so that when the gas-liquid mixture is discharged into the water tank 200 through the holes of the mesh cover 510, it forms air bubbles of different sizes. When the degree of overlap is small, the air bubbles are large and surge strongly. When the degree of overlap is large, the air bubbles are small and evenly distributed. The original cold water in the auxiliary water tank 200 is fully mixed with the return water source. VI. Gas recycling and cooling intensity adjustment: After the gas is discharged from the mesh cover 510 into the water tank 200, it rises to the inner top wall and is drawn back by the air pump 210 for recycling. The opening of the solenoid valve 331 on the outside of the exhaust pipe 330 is adjusted to change the jet volume, thereby synchronously changing the speed of the spiral blade 400, the interlacing frequency of the mesh cover 510 and the mixing intensity of the water tank 200, so as to realize the on-demand control of the cooling intensity. 7. Extrusion granulation: After thorough mixing and cooling with temperature control, the molten material is extruded into strips from the die of the twin-screw extruder 100. The strips are then granulated, cooled, and dried by the pelletizing device to obtain the finished calcium carbonate filler masterbatch.

[0042] The electrical components used in this application can be pre-programmed and controlled by the PLC controller on the twin-screw extruder 100. The power supply of each electrical component can be either built-in power supply or AC power supply, and the specific power supply method can be selected according to the actual usage requirements.

[0043] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0044] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A low-temperature extrusion preparation apparatus for calcium carbonate filler masterbatch, characterized in that, include: A twin-screw extruder (100) and a water tank (200) installed on its outside. A water inlet pipe (110) and a return pipe (120) connected to the water tank (200) are fixedly installed on one side of the water tank (200). A flow-gathering pipe (130) connected to the outside of the return pipe (120) is fixedly connected to it. The gas guide (300) is located inside the return pipe (120) and is used for circulating gas transport; The spiral blade (400) is rotatably connected to the interior of the return pipe (120); A mixing component (500) is disposed inside a water tank (200). The mixing component (500) includes two mesh covers (510) and a slider (520). The bottom mesh cover (510) is rotatable along its own axis. The slider (520) is fixedly connected to the top of the bottom mesh cover (510). One side of the slider (520) is slidably connected to the inside of the top mesh cover (510).

2. The low-temperature extrusion preparation apparatus for calcium carbonate filler masterbatch according to claim 1, characterized in that, The air guide (300) includes: An annular pipe (310) is installed inside the water tank (200); Branch pipes (320) are numerous and arranged in a ring, with one end connected to the ring pipe (310) and the other end extending into the interior of the return pipe (120); There are two exhaust pipes (330), which are positioned horizontally above the axis of the return pipe (120), and the ends of the exhaust pipes (330) are located on the side of the spiral blades (400) away from the water tank (200).

3. The low-temperature extrusion preparation apparatus for calcium carbonate filler masterbatch according to claim 2, characterized in that: The return pipe (120) has a cavity (121) inside. The branch pipe (320) and the exhaust pipe (330) are connected to the cavity (121) at the ends away from the water tank (200). A solenoid valve (331) is installed on the outside of the exhaust pipe (330).

4. The low-temperature extrusion preparation apparatus for calcium carbonate filler masterbatch according to claim 1, characterized in that: The return pipe (120) is fixedly connected to the end of the water tank (200) with a connecting pipe (122). The top mesh cover (510) is fixedly installed inside the connecting pipe (122), and the bottom mesh cover (510) is rotatably connected to the inside of the connecting pipe (122).

5. The low-temperature extrusion preparation apparatus for calcium carbonate filler masterbatch according to claim 1, characterized in that: The spiral blade (400) has a rotating shaft (410) fixedly inserted inside, and the return pipe (120) and the connecting pipe (122) are both fixedly connected with supports sleeved to the outside of the rotating shaft (410).

6. The low-temperature extrusion preparation apparatus for calcium carbonate filler masterbatch according to claim 5, characterized in that: A scraper (411) is fixedly connected to the outside of the rotating shaft (410), and a vertical rod (511) is fixedly connected to the bottom of the bottom mesh cover (510). The vertical rod (511) is located on the movement path of the scraper (411).

7. The low-temperature extrusion preparation apparatus for calcium carbonate filler masterbatch according to claim 2, characterized in that: An arc plate (321) is fixedly connected between each of two adjacent branch pipes (320), and the arc plate (321) is embedded in the interior of the return pipe (120).

8. The low-temperature extrusion preparation apparatus for calcium carbonate filler masterbatch according to claim 2, characterized in that: An air pump (210) is fixedly installed on the outside of the water tank (200). Both the output end and the input end of the air pump (210) are fixedly connected to a bend pipe (220). One end of the bend pipe (220) is inserted into and fixedly connected to the inside of the water tank (200). One end of the bottom bend pipe (220) is connected to the inside of the annular pipe (310).

9. The low-temperature extrusion preparation apparatus for calcium carbonate filler masterbatch according to claim 1, characterized in that: Elastic ropes (521) are fixedly connected to both sides of the slider (520), and the end of the elastic rope (521) away from the slider (520) is fixedly connected to the inside of the top mesh cover (510).

10. A low-temperature extrusion preparation process for calcium carbonate filler masterbatch according to any one of claims 1-9, characterized in that, Includes the following steps:

1. Melt mixing: The premixed material is fed into the twin-screw extruder (100) through the feeding system. Under the forced conveying and shearing mixing action of the screw, the material is gradually melted and plasticized. The calcium carbonate powder is uniformly dispersed in the carrier resin to form a molten mixture.

2. Cooling water circulation and cooling: During the melting and mixing process, the cooling water circulation is started simultaneously. The water pump draws out the low-temperature water source in the water tank (200), transports it along the water inlet pipe (110) and enters the barrel water channel of the twin screw extruder (100) through the water inlet connection pipe to cool the barrel and screw. The water source after absorbing heat becomes high-temperature return water, flows into the convergence pipe (130) through the return connection pipe and then flows back to the water tank (200) along the return pipe (120) to form continuous water circulation cooling, so that the barrel temperature is controlled within the preset low-temperature extrusion range.

3. Low-temperature gas pre-cooling: The gas pump (210) is started to extract the low-temperature gas from the top of the water tank (200) and transport it to the ring pipe (310) through the bend pipe (220). When the gas flows through the ring pipe (310) and the branch pipe (320), it is further cooled by the low-temperature water source in the water tank (200). Then it enters the cavity (121) of the return pipe (120) to cool the pipe wall. Then it is sprayed into the return pipe (120) through the exhaust pipe (330) to contact the high-temperature return water for heat exchange, and pre-cool the return water source. IV. Gas-liquid mixing and spiral blade (400) drive: The gas ejected from the exhaust pipe (330) drives the spiral blade (400) inside the return pipe (120) to rotate. The rotating spiral blade (400) destroys the laminar boundary layer of the return water flow and stirs the gas and liquid to mix fully and enhance heat exchange. On the other hand, it continuously flushes the inner wall of the return pipe (120) and reduces dirt accumulation.

5. The mesh cover (510) adjusts the mixing of air bubbles with the water tank (200). The spiral blade (400) rotates, driving the rotating shaft (410) to rotate. The scraper (411) on the rotating shaft (410) repeatedly hits the vertical rod (511) on the bottom mesh cover (510), causing the bottom mesh cover (510) to rotate around the shaft. The bottom mesh cover (510) continuously changes the degree of overlap with the top mesh cover (510), so that when the gas-liquid mixture is discharged into the water tank (200) through the holes of the mesh cover (510), it forms air bubbles of different sizes. When the degree of overlap is small, the air bubbles are large and surge strongly. When the degree of overlap is large, the air bubbles are small and evenly distributed. The original cold water in the auxiliary water tank (200) is fully mixed with the return water source. VI. Gas recycling and cooling intensity adjustment: After the gas is discharged from the mesh cover (510) into the water tank (200), it rises to the inner top wall and is drawn back by the air pump (210) for recycling. The opening of the solenoid valve (331) on the outside of the exhaust pipe (330) is adjusted to change the jet volume, thereby synchronously changing the rotation speed of the spiral blade (400), the cross frequency of the mesh cover (510) and the mixing intensity of the water tank (200), so as to realize the on-demand control of cooling intensity.

7. Extrusion granulation: After thorough mixing and cooling, the molten material is extruded into strips from the die of a twin-screw extruder (100), then granulated, cooled, and dried by a pelletizing device to obtain the finished calcium carbonate filler masterbatch.

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