Separation apparatus and its applications, apparatus and method for pre-treatment of PVC-containing waste plastics

Abstract

The present application relates to the technical field of waste plastic pretreatment, and particularly relates to a conveying device and application thereof, and a device and method for pretreatment of waste plastic containing PVC. The separation device provided by the present application comprises a screw propeller, so that the material and the separation fluid are fully contacted and subjected to sedimentation separation in a sedimentation separation zone, and the obtained heavy material and light material are conveyed in the downstream direction. The separation device provided by the present application is used for secondary separation in the pretreatment of waste plastic containing PVC, and can realize the separation of waste plastic rich in dechlorinated waste plastic and waste plastic rich in chlorine from relatively light waste plastic, and obtain dechlorinated waste plastic with low chlorine content.

Description

Technical Field

[0001] This invention relates to the field of waste plastic pretreatment technology, specifically to a conveying device and its application, and a device and method for pretreating PVC-containing waste plastics. Background Technology

[0002] A large amount of waste plastic is generated globally every year. Recycling waste plastic can not only solve environmental pollution problems, but also recycle waste carbon and hydrogen resources.

[0003] Waste plastics contain a large amount of PVC, which is corrosive to equipment and can deactivate catalysts in downstream processing, thus requiring pretreatment. Pretreatment methods mainly fall into two categories: physical and chemical. Compared to chemical pretreatment, physical pretreatment consumes less energy, but its dechlorination effect is limited. Waste plastics separated by physical methods such as flotation and electrostatics typically have a high PVC content, failing to meet the requirements for subsequent recycling. Therefore, there is an urgent need for a separation device for the pretreatment of PVC-containing waste plastics, efficiently removing PVC from them. Summary of the Invention

[0004] The purpose of this invention is to overcome the problems of existing separation equipment for pretreatment of PVC-containing waste plastics, such as difficulty in separating PVC, high PVC content in the separated dechlorinated waste plastics, and high energy consumption. This invention provides a separation device and its application, as well as a device and method for pretreatment of PVC-containing waste plastics. The separation device utilizes the density difference of materials to achieve sedimentation separation of heavy and light materials. Simultaneously, it is used for secondary separation of PVC-containing waste plastics, achieving the dechlorination of chlorinated waste plastics from relatively light waste plastics.

[0005] To achieve the above objectives, a first aspect of the present invention provides a separation device comprising: a housing having a sedimentation separation zone and a product zone in communication, and a screw propeller; the screw propeller comprising: a motor and at least one screw, the screw being disposed near the bottom of the housing and penetrating into the interior of the sedimentation separation zone;

[0006] The sedimentation separation zone is provided with a material inlet and at least one separation fluid inlet; the product zone is provided with a heavy material outlet and a light material outlet, as well as a partition plate separating the heavy material outlet and the light material outlet.

[0007] The motor drives the screw to rotate, so that the material passing through the material inlet and the separation fluid passing through the separation fluid inlet come into contact and settle in the separation and settling zone. The resulting heavy material and light material are led out through the heavy material outlet and the light material outlet, respectively, under the action of the screw.

[0008] The second aspect of the present invention provides an application of the separation device provided in the first aspect in the pretreatment of PVC-containing waste plastics.

[0009] A third aspect of the present invention provides an apparatus for pretreatment of PVC-containing waste plastics, the apparatus comprising: a waste plastic silo, a primary separation device, a secondary separation device, a first de-separation device, and a dechlorinated waste plastic tank connected in sequence, and a second de-separation device and a chlorinated waste plastic tank connected in sequence with the primary separation device;

[0010] The waste plastic bin is used to introduce PVC-containing waste plastic into the primary separation equipment;

[0011] The primary separation equipment is used to contact the PVC-containing waste plastic and the first separation fluid and centrifuge them to obtain centrifuged separation fluid, relatively light waste plastic and relatively heavy waste plastic;

[0012] The secondary separation device is connected to the relatively light waste plastic outlet of the primary separation device, and is used to contact the relatively light waste plastic and the second separation fluid for sedimentation separation to obtain dechlorination-rich waste plastic and chlorine-rich waste plastic;

[0013] The first separation device is connected to the outlet of the dechlorination-rich waste plastic of the secondary separation device, and is used to perform a first separation of the dechlorination-rich waste plastic to obtain a first separation fluid and dechlorination waste plastic;

[0014] The dechlorination waste plastic tank is connected to the dechlorination waste plastic outlet of the first dechlorination separation equipment and is used to store the dechlorination waste plastic;

[0015] The second separation device is connected to the outlet of the relatively heavy waste plastic of the first separation device, and is used to perform a second separation of the relatively heavy waste plastic to obtain a second separation fluid, solid impurities and chlorine-containing waste plastic;

[0016] The chlorine-containing waste plastic tank is connected to the chlorine-containing waste plastic outlet of the second separation device and is used to store the chlorine-containing waste plastic;

[0017] The secondary separation device is the separation device provided by the first aspect.

[0018] A fourth aspect of the present invention provides a method for pretreatment of PVC-containing waste plastics, the method comprising the following steps:

[0019] (1) Contact the PVC-containing waste plastic and the first separation fluid and centrifuge them to obtain centrifuged separation fluid, relatively light waste plastic and relatively heavy waste plastic;

[0020] (2) In the separation equipment provided in the first aspect, the relatively light waste plastic added through the material inlet and the second separation fluid added through the separation fluid inlet are contacted and separated by the action of the screw to obtain chlorine-rich waste plastic and dechlorination-rich waste plastic, which are respectively led out through the heavy material outlet and the light material outlet.

[0021] (3) The dechlorinated waste plastic is subjected to a first separation process to obtain a first separation fluid and dechlorinated waste plastic;

[0022] (4) The relatively heavy waste plastic is subjected to a second separation to obtain a second separation fluid, solid impurities and chlorine-containing waste plastic.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] (1) The separation device provided by the present invention includes a screw propeller, which enables the material and the separation fluid to fully contact and settle in the sedimentation separation zone, so that the heavy material and the light material are transported downstream; in particular, combined with the rotation speed of the screw and the structure of the screw blade, the separation of heavy material and light material in the material is further promoted.

[0025] (2) The separation equipment provided by the present invention is used for secondary separation of PVC-containing waste plastic pretreatment, especially for sedimentation separation of relatively light waste plastic in the separation equipment, which can realize the separation of dechlorination-rich waste plastic and chlorine-rich waste plastic in relatively light waste plastic, and obtain dechlorination waste plastic with low chlorine content.

[0026] (3) The method for pretreatment of PVC-containing waste plastics provided by the present invention involves two-stage separation of PVC-containing waste plastics. First, the PVC-containing waste plastics are separated by centrifugation to obtain relatively light waste plastics and relatively heavy waste plastics. Then, the relatively light waste plastics are separated by sedimentation to obtain dechlorination-rich waste plastics and chlorine-rich waste plastics. Then, the dechlorination-rich waste plastics and the relatively heavy waste plastics are separated to obtain dechlorinated waste plastics and chlorine-containing waste plastics, thereby effectively removing the chlorine content from the PVC-containing waste plastics. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of a separation device structure provided by the present invention;

[0028] Figure 2 This is a schematic diagram of a device for pretreating PVC-containing waste plastics provided by the present invention.

[0029] Explanation of reference numerals in the attached figures

[0030] 1. Waste plastic storage bins 2. Primary separation equipment 3. Secondary separation equipment

[0031] 4. First separation unit; 5. Dechlorinated waste plastic tank; 6. Second separation unit

[0032] 7. Chlorine-containing waste plastic containers; 8. Fluid recovery tanks; 9. Mechanical debris collection tanks.

[0033] 10. First conveying equipment; 11. Second conveying equipment; 12. Second conveying equipment

[0034] 001. PVC-containing waste plastics; 002. First separation fluid; 003. Relatively lightweight waste plastics.

[0035] 004. Relatively heavy waste plastics; 005. Centrifugal separation fluid; 006. Secondary separation fluid.

[0036] 007, Dechlorinated waste plastics; 008, Chlorine-rich waste plastics; 009, First separation fluid.

[0037] 010, Solid mechanical impurities; 011, Dechlorinated waste plastics; 012, Second separation fluid.

[0038] 013. Chlorine-containing waste plastics

[0039] 31. Separating fluid inlet; 32. Material inlet; 33. Motor

[0040] 34. Rotating shaft; 35. Spiral blade; 36. Partition plate

[0041] 37. Heavy material outlet; 38. Light material outlet; 39. Shell. Detailed Implementation

[0042] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0043] In this invention, unless otherwise specified, the “top” of the container refers to the 0-10% position of the container from top to bottom; the “upper part” of the container refers to the 10-40% position of the container from top to bottom; the “middle part” of the container refers to the 40-60% position of the container from top to bottom; the “lower part” of the container refers to the 60-90% position of the container from top to bottom; and the “bottom” of the container refers to the 90-100% position of the container from top to bottom.

[0044] In this invention, unless otherwise specified, the terms "first," "second," and "third" do not indicate a sequential order, nor do they limit the specific materials or steps; they are merely used to distinguish between different materials or steps. For example, in "first conveying equipment," "second conveying equipment," and "third conveying equipment," "first," "second," and "third" are simply used to distinguish that these are not the same conveying equipment; similarly, in "first separation" and "second separation," "first" and "second" are simply used to distinguish that these are not the same separation process.

[0045] The first aspect of the present invention provides a separation device, the separation device comprising: a housing having a sedimentation separation zone and a product zone in communication, and a screw propeller; the screw propeller comprising: a motor and at least one screw, the screw being disposed near the bottom of the housing and penetrating into the interior of the sedimentation separation zone;

[0046] The sedimentation separation zone is provided with a material inlet and at least one separation fluid inlet; the product zone is provided with a heavy material outlet and a light material outlet, as well as a partition plate separating the heavy material outlet and the light material outlet.

[0047] The motor drives the screw to rotate, so that the material passing through the material inlet and the separation fluid passing through the separation fluid inlet come into contact and settle in the separation and settling zone. The resulting heavy material and light material are led out through the heavy material outlet and the light material outlet, respectively, under the action of the screw.

[0048] The separation device provided by this invention mainly utilizes the density difference of materials in the separating fluid, combined with a screw propeller, so that the heavy materials and light materials in the material further settle and separate under the action of the screw, causing the light materials to float, while the heavy materials are conveyed by the screw. The resulting heavy materials and light materials are discharged from the heavy material outlet and the light material outlet, respectively, thereby realizing the separation of light materials and heavy materials in the material.

[0049] In this invention, to improve the settling and separation effect of the material, preferably, the material inlet is located at the top of the settling and separation zone, and the separation fluid inlet is located on the side of the settling and separation zone.

[0050] According to the present invention, preferably, the number of the separation fluid inlets is ≥2, and more preferably 2, 3, 4, or 5.

[0051] According to the present invention, preferably, the ratio of the length of the screw extending into the settling separation zone to the length of the settling separation zone is 0.5-1:1, for example, 0.5:1, 0.7:1, 0.8:1, 0.9:1, and any value within the range of any two values, preferably 0.7-0.9:1. Wherein, the length of the settling separation zone refers to the projected length of the settling separation zone on the horizontal plane.

[0052] According to the present invention, preferably, the screw speed is 1-60 rpm, for example, 1 rpm, 5 rpm, 10 rpm, 15 rpm, 20 rpm, 25 rpm, 30 rpm, and any value in any range of any two values, preferably 5-30 rpm, more preferably 15-30 rpm.

[0053] According to the present invention, preferably, the number of screws is 1-2, more preferably 2.

[0054] According to the present invention, preferably, the screw includes a rotating shaft and helical blades disposed on the rotating shaft; more preferably, the pitch of the helical blades is 1-500 mm, more preferably 10-300 mm; the closest distance from the upper / lower edge of the helical blades to the rotating shaft is ≤200 mm, more preferably 20-100 mm. By designing the pitch of the helical blades, the turbulence caused by the screw driving the helical blades to rotate is adjusted, thereby enhancing the thorough mixing of the liquid-solid fluid; at the same time, by controlling the closest distance from the upper / lower edge of the helical blades to the rotating shaft, the downstream speed of the bottom solid is controlled.

[0055] According to the present invention, preferably, the ratio of the length of the helical blade winding around the rotating shaft to the length of the screw extending into the settling separation zone is 0.6-1:1, more preferably 0.7-0.99:1. Using these preferred conditions is beneficial for promoting the separation of heavy and light materials in the material.

[0056] According to the present invention, preferably, the cross-section of the rotating shaft is circular and / or rectangular, and more preferably circular.

[0057] According to the present invention, preferably, the projected length of the shell in the horizontal plane is ≥0.5m, preferably 1-3m, for example, 1m, 2m, 3m, and any value within the range of any two values.

[0058] According to the present invention, preferably, the ratio of the projected lengths of the sedimentation separation zone and the product zone in the horizontal plane is 1-10:1, for example, 1:1, 3:1, 4:1, 5:1, 6:1, 7:1, 10:1, and any value in any range of any two values, preferably 3-7:1.

[0059] According to the present invention, preferably, along the material flow direction, the product zone is disposed below the sedimentation separation zone, and the bottom of the product zone is lower than the bottom of the sedimentation separation zone.

[0060] According to the present invention, preferably, the height of the partition plate is higher than the upper edge of the screw; more preferably, the difference between the height of the partition plate and the upper edge of the screw is 0.5-50cm, for example, 0.5cm, 5cm, 8cm, 10cm, 20cm, 30cm, 40cm, 50cm, and any value within the range of any two values, preferably 5-10cm.

[0061] A schematic diagram of the structure of a separation device provided by the present invention is shown below. Figure 1 As shown, the separation device includes: a housing 39 having a communicating sedimentation separation zone and a product zone, and a screw propeller; the screw propeller includes: a motor 33 and two screws, the screws being disposed near the bottom of the housing 39 and penetrating into the interior of the sedimentation separation zone; the screws include a rotating shaft 34 and helical blades 35 disposed on the rotating shaft 34;

[0062] The sedimentation separation zone is provided with a material inlet 32 ​​and two separation fluid inlets 31; the product zone is provided with a heavy material outlet 37 and a light material outlet 38, as well as a partition plate 36 separating the heavy material outlet 37 and the light material outlet 38.

[0063] Among them, the motor 33 drives the screw to rotate, so that the material passing through the material inlet 32 ​​and the separation fluid passing through the separation fluid inlet 31 come into contact and settle in the separation settling zone. The resulting heavy material and light material are led out through the heavy material outlet 37 and the light material outlet 38 respectively under the action of the screw.

[0064] The height of the partition plate 36 is higher than the upper edge of the spiral blade 35.

[0065] According to a particularly preferred embodiment of the present invention, the separation device includes: a housing having a communicating sedimentation separation zone and a product zone, and a screw propeller; the screw propeller includes: a motor and at least one screw, the screw being disposed near the bottom of the housing and penetrating into the interior of the sedimentation separation zone;

[0066] The sedimentation separation zone is provided with a material inlet and at least one separation fluid inlet; the product zone is provided with a heavy material outlet and a light material outlet, as well as a partition plate separating the heavy material outlet and the light material outlet.

[0067] The motor drives the screw to rotate, so that the material passing through the material inlet and the separation fluid passing through the separation fluid inlet come into contact and settle in the separation settling zone. The resulting heavy material and light material are led out through the heavy material outlet and the light material outlet, respectively, under the action of the screw.

[0068] The projected length of the shell in the horizontal plane is 1-3m; the ratio of the length of the screw extending into the settling separation zone to the length of the settling separation zone is 0.7-0.9:1; and the rotational speed of the screw is 15-30rpm.

[0069] The difference between the height of the partition plate and the upper edge of the screw is 0.5-50cm.

[0070] The second aspect of the present invention provides an application of the separation device provided in the first aspect in the pretreatment of PVC-containing waste plastics.

[0071] The relatively lightweight waste plastics obtained by centrifugation of PVC-containing waste plastics are further separated by sedimentation in the separation equipment provided by the present invention to remove the chlorine-rich waste plastics from the relatively lightweight waste plastics, thereby obtaining dechlorinated waste plastics.

[0072] A third aspect of the present invention provides an apparatus for pretreatment of PVC-containing waste plastics, the apparatus comprising: a waste plastic silo, a primary separation device, a secondary separation device, a first de-separation device, and a dechlorinated waste plastic tank connected in sequence, and a second de-separation device and a chlorinated waste plastic tank connected in sequence with the primary separation device;

[0073] The waste plastic bin is used to introduce PVC-containing waste plastic into the primary separation equipment;

[0074] The primary separation equipment is used to contact the PVC-containing waste plastic and the first separation fluid and centrifuge them to obtain centrifuged separation fluid, relatively light waste plastic and relatively heavy waste plastic;

[0075] The secondary separation device is connected to the relatively light waste plastic outlet of the primary separation device, and is used to contact the relatively light waste plastic and the second separation fluid for sedimentation separation to obtain dechlorination-rich waste plastic and chlorine-rich waste plastic;

[0076] The first separation device is connected to the outlet of the dechlorination-rich waste plastic of the secondary separation device, and is used to perform a first separation of the dechlorination-rich waste plastic to obtain a first separation fluid and dechlorination waste plastic;

[0077] The dechlorination waste plastic tank is connected to the dechlorination waste plastic outlet of the first dechlorination separation equipment and is used to store the dechlorination waste plastic;

[0078] The second separation device is connected to the outlet of the relatively heavy waste plastic of the first separation device, and is used to perform a second separation of the relatively heavy waste plastic to obtain a second separation fluid, solid impurities and chlorine-containing waste plastic;

[0079] The chlorine-containing waste plastic tank is connected to the chlorine-containing waste plastic outlet of the second separation device and is used to store the chlorine-containing waste plastic;

[0080] The secondary separation device is the separation device provided by the first aspect.

[0081] In this invention, unless otherwise specified, the terms "relatively heavy waste plastics" and "relatively light waste plastics" are based on whether or not they contain PVC, and generally, the density of waste plastics is >1.2 g / cm³. 3 If it is classified as relatively heavy waste plastic, it is classified as relatively light waste plastic.

[0082] In this invention, the type of primary separation equipment is not limited. Preferably, the primary separation equipment is a high-efficiency centrifuge with a rotation speed ≥8000 rpm, preferably 8000-10000 rpm; and a time of 1-30 min, preferably 5-20 min.

[0083] In this invention, the type of the first separation equipment is widely selectable, as long as the dechlorinated waste plastic is subjected to the first separation process to obtain the first separation fluid and the dechlorinated waste plastic. The first separation equipment includes, but is not limited to, centrifuges, spin dryers, dryers, and other equipment used for liquid-solid separation.

[0084] In this invention, the type of the second separation equipment is widely selectable, as long as the relatively heavy waste plastic is subjected to the second separation to obtain the second separated fluid, solid impurities, and chlorine-containing waste plastic. The second separation equipment includes, but is not limited to, centrifuges, spin dryers, dryers, and other equipment used for liquid-solid separation.

[0085] According to the present invention, preferably, the outlet of the chlorine-rich waste plastic of the secondary separation device is connected to the inlet of the second de-separation device, for returning the chlorine-rich waste plastic and mixing it with the relatively heavy waste plastic.

[0086] According to the present invention, preferably, the device further includes a fluid recovery tank connecting the primary separation device and the secondary separation device.

[0087] According to the present invention, preferably, the centrifugal separation fluid outlet of the primary separation device is connected to the fluid recovery tank for recovering the centrifugal separation fluid as a circulating separation fluid.

[0088] According to the present invention, preferably, the first deseparated fluid outlet of the first deseparation device is connected to the fluid recovery tank for recycling the first deseparated fluid as a circulating separation fluid.

[0089] According to the present invention, preferably, the second deseparated fluid outlet of the second deseparation device is connected to the fluid recovery tank for recycling the second deseparated fluid as a circulating separation fluid.

[0090] According to the present invention, preferably, the device further includes: a solid impurity collection tank connected to the solid impurity outlet of the second separation device, for collecting the solid impurities.

[0091] According to the present invention, preferably, the apparatus further includes: a first conveying device connecting the relatively light waste plastic outlet of the primary separation device and the secondary separation device.

[0092] According to the present invention, preferably, the apparatus further includes a second conveying device that connects to the relatively heavy waste plastic outlet of the primary separation device and the second deseparation device.

[0093] According to the present invention, preferably, the device further includes a third conveying device connecting the waste plastic bin and the primary separation equipment.

[0094] In this invention, the types of the first conveying device, the second conveying device, and the third conveying device are not limited. The first conveying device, the second conveying device, and the third conveying device each independently include, but are not limited to, pumps, horizontal screw conveyors, spiral conveyors, etc.

[0095] This invention provides a schematic diagram of an apparatus for pretreating PVC-containing waste plastics, as shown below. Figure 2 As shown, the device includes: a waste plastic bin 1, a primary separation device 2, a secondary separation device 3, a first de-separation device 4, a dechlorinated waste plastic bin 5 connected in sequence, and a second de-separation device 6 and a chlorinated waste plastic bin 7 connected in sequence with the primary separation device 2;

[0096] The waste plastic silo 1 is used to introduce PVC-containing waste plastic 001 into the primary separation device 2; the primary separation device 2 is used to contact the PVC-containing waste plastic 001 and the first separation fluid 002 and perform centrifugal separation to obtain centrifuged separation fluid 005, relatively light waste plastic 003, and relatively heavy waste plastic 004; the secondary separation device 3 is connected to the relatively light waste plastic outlet of the primary separation device 2 and is used to contact the relatively light waste plastic 003 and the second separation fluid 006 and perform sedimentation separation to obtain dechlorination-rich waste plastic 007 and chlorine-rich waste plastic 008; the first dechlorination separation device 4 is connected to the dechlorination-rich waste plastic of the secondary separation device 3. The plastic outlet is used to perform a first separation of dechlorinated waste plastic 007 to obtain a first separation fluid 009 and dechlorinated waste plastic 011; the dechlorinated waste plastic tank 5 is connected to the dechlorinated waste plastic outlet of the first separation device 4 and is used to store the dechlorinated waste plastic 011; the second separation device 6 is connected to the relatively heavy waste plastic outlet of the first separation device 2 and is used to perform a second separation of relatively heavy waste plastic 004 to obtain a second separation fluid 012, solid impurities 010 and chlorinated waste plastic 013; the chlorinated waste plastic tank 7 is connected to the chlorinated waste plastic outlet of the second separation device 6 and is used to store the chlorinated waste plastic 013;

[0097] Among them, the outlet of the chlorine-rich waste plastic of the secondary separation device 3 is connected to the inlet of the second separation device 6, which is used to return the chlorine-rich waste plastic 008 and mix it with the relatively heavy waste plastic 004.

[0098] The device also includes: a fluid recovery tank 8 connecting the primary separation device 2 and the secondary separation device 3; the centrifugal separation fluid outlet of the primary separation device 2 is connected to the fluid recovery tank 8, the first deseparation fluid outlet of the first deseparation device 4 is connected to the fluid recovery tank 8, and the second deseparation fluid outlet of the second deseparation device 6 is connected to the fluid recovery tank 8.

[0099] The device also includes: a solid impurity collection tank 9 connected to the solid impurity outlet of the second separation device 6;

[0100] The device also includes: a first conveying device 10 connecting the relatively light waste plastic outlet of the primary separation device 2 and the secondary separation device 3; a second conveying device 11 connecting the relatively heavy waste plastic outlet of the primary separation device 2 and the secondary separation device 6; and a third conveying device 12 connecting the waste plastic bin 1 and the primary separation device 2.

[0101] A fourth aspect of the present invention provides a method for pretreatment of PVC-containing waste plastics, the method comprising the following steps:

[0102] (1) Contact the PVC-containing waste plastic and the first separation fluid and centrifuge them to obtain centrifuged separation fluid, relatively light waste plastic and relatively heavy waste plastic;

[0103] (2) In the separation equipment provided in the first aspect, the relatively light waste plastic added through the material inlet and the second separation fluid added through the separation fluid inlet are contacted and separated by the action of the screw to obtain chlorine-rich waste plastic and dechlorination-rich waste plastic, which are respectively led out through the heavy material outlet and the light material outlet.

[0104] (3) The dechlorinated waste plastic is subjected to a first separation process to obtain a first separation fluid and dechlorinated waste plastic;

[0105] (4) The relatively heavy waste plastic is subjected to a second separation to obtain a second separation fluid, solid impurities and chlorine-containing waste plastic.

[0106] In some embodiments of the present invention, preferably, in step (1), the weight ratio of the PVC-containing waste plastic and the first separation fluid is 1:0.1-100, for example, 1:0.1, 1:1, 1:5, 1:10, 1:20, 1:30, 1:40, 1:50, 1:60, 1:70, 1:80, 1:100, and any value within the range of any two values, preferably 1:5-70, more preferably 1:5-50.

[0107] In some embodiments of the present invention, preferably, the equivalent diameter of the PVC-containing waste plastic is <50mm, more preferably <20mm, more preferably <10mm, and most preferably 1-5mm.

[0108] In some embodiments of the present invention, preferably, the PVC content is 0.1-50 wt%, more preferably 0.1-25 wt%, based on the total weight of the PVC-containing waste plastics. The chlorine content in the waste plastics is measured by first dissolving the waste plastics and then calculating the chloride ion concentration by ICP measurement.

[0109] In this invention, the centrifugal separation aims to separate the waste plastic into centrifugal fluid, relatively light waste plastic, and relatively heavy waste plastic. Preferably, the conditions for centrifugal separation include: a rotational speed ≥ 8000 rpm, more preferably 8000-10000 rpm; and a time of 1-30 min, more preferably 5-20 min.

[0110] In some embodiments of the present invention, preferably, in step (2), the weight ratio of the relatively lightweight waste plastic and the second separated fluid is 1:10-100, for example, 1:10, 1:20, 1:30, 1:40, 1:50, 1:80, 1:100, and any value in any range of any two values, preferably 1:20-50.

[0111] In some embodiments of the present invention, preferably, the screw rotates at a speed of 1-60 rpm, more preferably 5-30 rpm, and even more preferably 15-30 rpm.

[0112] In this invention, the first separating fluid and the second separating fluid are each independently a fluid that alters the surface tension or density of the material. Preferably, the first separating fluid and the second separating fluid are each independently selected from at least one of water, optionally an inorganic substance, and optionally an organic substance.

[0113] In some embodiments of the present invention, preferably, based on the total weight of the first separated fluid / second separated fluid, the water content is 0-100wt%, preferably 90-100wt%, the inorganic content is 0-50wt%, preferably 0-15wt%, and the organic content is 0-50wt%, preferably 0-15wt%.

[0114] In some embodiments of the present invention, preferably, the inorganic substance is a soluble compound, and more preferably selected from at least one of sodium chloride, calcium chloride, sodium nitrate, sodium hydroxide, and potassium hydroxide.

[0115] According to the present invention, preferably, the organic compound is selected from at least one of nonpolar organic compounds, nonpolar organic compounds, and surfactants; more preferably, the nonpolar organic compound is selected from at least one of acetone, tetrabromoethane, ethanol, ethylene glycol, and glycerol; the polar organic compound is selected from at least one of methanol, ethanol, tetrahydrofuran, and DMF; and the surfactant is selected from at least one of sulfated oil, higher fatty alcohol sulfates, and sodium dodecylbenzenesulfonate.

[0116] In this invention, the first separation is intended to perform a first separation of the relatively light waste plastic to obtain a first separation fluid and dechlorinated waste plastic. Preferably, in step (3), the conditions for the first separation include: rotation speed ≥ 3000 rpm, 5000-10000 rpm; time 1-30 min, preferably 5-20 min.

[0117] In this invention, the second separation is intended to perform a second separation of the relatively heavy waste plastics to obtain a second separated fluid, solid impurities, and chlorine-containing waste plastics. Preferably, in step (4), the conditions for the second separation include: a rotation speed ≥ 3000 rpm, preferably 5000-8000 rpm; and a time of 1-30 min, preferably 5-15 min.

[0118] According to the present invention, preferably, the method further includes: returning the chlorine-rich waste plastics and mixing them with the relatively heavy waste plastics for the second separation. This arrangement is intended to aggregate the chlorine-containing waste plastics for easier recycling.

[0119] According to the present invention, preferably, the method further includes: recovering the centrifugally separated fluid as a circulating separated fluid.

[0120] According to the present invention, preferably, the method further includes: independently recovering the first deseparated fluid and the second deseparated fluid as circulating separation fluids.

[0121] According to the present invention, preferably, the method further includes: collecting the solid impurities.

[0122] The present invention will be described in detail below through embodiments.

[0123] In the examples and comparative examples, the chlorine content in chlorinated waste plastics and dechlorinated waste plastics was measured by first dissolving the chlorinated waste plastics and dechlorinated waste plastics, and then calculating the chloride ion concentration by measuring the chloride ion concentration through ICP.

[0124] The PVC-containing waste plastics include polyethylene, polypropylene and PVC; wherein, based on the weight of the PVC-containing waste plastics, the PVC content is 10 wt%; and the equivalent diameter is 1 mm.

[0125] Calculation formula:

[0126]

[0127] The units for chloride ion concentration in the solution containing chlorine-containing waste plastics are g / g; the units for the mass of the solution containing chlorine-containing waste plastics are g; and the units for the mass of the waste plastics containing chlorine are g.

[0128]

[0129] The units for chloride ion concentration in the solution of dechlorinated waste plastics are g / g; the units for the mass of the solution of dechlorinated waste plastics are g; and the units for the mass of dechlorinated waste plastics are g.

[0130] Example 1

[0131] (1) Separation equipment, such as Figure 1 As shown, the separation device includes: a housing 39 having a communicating sedimentation separation zone and a product zone, and a screw propeller; the screw propeller includes: a motor 33 and two screws, the screws being located near the bottom of the housing 39 and penetrating into the interior of the sedimentation separation zone; the screws include a rotating shaft 34 and helical blades 35 disposed on the rotating shaft 34;

[0132] The sedimentation separation zone is provided with a material inlet 32 ​​and two separation fluid inlets 31; the product zone is provided with a heavy material outlet 37 and a light material outlet 38, as well as a partition plate 36 separating the heavy material outlet 37 and the light material outlet 38.

[0133] Among them, the motor 33 drives the screw to rotate, so that the material passing through the material inlet 32 ​​and the separation fluid passing through the separation fluid inlet 31 come into contact and settle in the separation settling zone. The resulting heavy material and light material are led out through the heavy material outlet 37 and the light material outlet 38 respectively under the action of the screw.

[0134] The height of the partition plate 36 is higher than the upper edge of the spiral blade 35.

[0135] The ratio of the length of the screw extending into the settling separation zone to the length of the settling separation zone is 0.8:1; the screw rotation speed is 20 rpm; the ratio of the length of the helical blades wound around the rotating shaft to the length of the screw extending into the settling separation zone is 0.8:1; the pitch of the helical blades is 20 mm; the closest distance from the outer diameter of the helical blades to the rotating shaft is 30 mm; the projected length of the shell in the horizontal plane is 3 m; the ratio of the projected lengths of the settling separation zone and the product zone in the horizontal plane is 5:1; and the difference between the height of the separator plate and the upper edge of the screw is 6 cm.

[0136] (2) Schematic diagram of the device for pretreatment of PVC waste plastics, as shown Figure 2 As shown, the device includes: a waste plastic bin 1, a primary separation device 2, a secondary separation device 3 (using the above separation device as a secondary separation device), a first de-separation device 4, a dechlorinated waste plastic bin 5, and a second de-separation device 6 and a chlorinated waste plastic bin 7 connected in sequence with the primary separation device 2;

[0137] The outlet of the chlorine-rich waste plastic in the secondary separation device 3 is connected to the inlet of the second separation device 6;

[0138] The device also includes: a fluid recovery tank 8 connecting the primary separation device 2 and the secondary separation device 3; the centrifugal separation fluid outlet of the primary separation device 2 is connected to the fluid recovery tank 8, the first deseparation fluid outlet of the first deseparation device 4 is connected to the fluid recovery tank 8, and the second deseparation fluid outlet of the second deseparation fluid 6 is connected to the fluid recovery tank 8;

[0139] The device also includes: a solid impurity collection tank 9 connected to the solid impurity outlet of the second separation device 6;

[0140] The device also includes: a first conveying device 10 connecting the relatively light waste plastic outlet of the primary separation device 2 and the secondary separation device 3; a second conveying device 11 connecting the relatively heavy waste plastic outlet of the primary separation device 2 and the secondary separation device 6; and a third conveying device 12 connecting the waste plastic bin 1 and the primary separation device 2.

[0141] (3) A method for pretreatment of PVC-containing waste plastics, the method comprising the following steps:

[0142] a. Contact 100g of PVC-containing waste plastic with 5000g of deionized water and centrifuge (8000rpm, 10min) to obtain centrifuged separation fluid, relatively light waste plastic and relatively heavy waste plastic;

[0143] b. In the above separation equipment, 100g of relatively light waste plastic added through the material inlet and 5000g of deionized water added through the separation fluid inlet are contacted and separated by sedimentation under the action of the screw, resulting in dechlorination-rich waste plastic and chlorine-rich waste plastic, which are respectively led out through the light material outlet and the heavy material outlet.

[0144] c. Perform the first separation on the above-mentioned dechlorination-rich waste plastic (5000 rpm; 10 min) to obtain the first separation fluid and dechlorination-rich waste plastic S1;

[0145] d. The above-mentioned chlorine-rich waste plastics are returned and mixed with the above-mentioned relatively heavy waste plastics for a second separation (rotation speed 5000 rpm; time 8 min) to obtain the second separation fluid, solid impurities and chlorine-containing waste plastic P1;

[0146] The centrifugally separated fluid, the first deseparated fluid, and the second deseparated fluid are all recycled as centrifugal fluids.

[0147] The chlorine content in dechlorinated waste plastic S1 was 0.061 wt%; the chlorine content in dechlorinated waste plastic P1 was 25.6 wt%.

[0148] Example 2

[0149] The separation device shown in Example 1 is different in that the pitch of the spiral blades is replaced with 50 mm and the rotational speed of the screw is replaced with 10 rpm.

[0150] Following the apparatus and method for pretreatment of PVC-containing waste plastics as shown in Example 1, dechlorinated waste plastic S2 and chlorinated waste plastic P2 were obtained.

[0151] Among them, the chlorine content in dechlorinated waste plastic S2 is 0.089 wt%; the chlorine content in chlorinated waste plastic P2 is 23.8 wt%.

[0152] Example 3

[0153] The separation device is the same as that shown in Example 1, except that the projected length of the shell in the horizontal plane is replaced with 0.2m;

[0154] Following the apparatus and method for pretreatment of PVC-containing waste plastics as shown in Example 1, dechlorinated waste plastic S2 and chlorinated waste plastic P3 were obtained.

[0155] Among them, the chlorine content in dechlorinated waste plastic S3 was 0.096 wt%; the chlorine content in chlorinated waste plastic P3 was 22.6 wt%.

[0156] Example 4

[0157] The separation device shown in Example 1 differs in that the height of the partition plate is equal to the upper edge of the screw.

[0158] According to the apparatus and method for pretreatment of PVC-containing waste plastics shown in Example 1, dechlorinated waste plastic S4 and chlorinated waste plastic P4 are obtained.

[0159] Among them, the chlorine content in dechlorinated waste plastic S4 was 0.102 wt%; the chlorine content in chlorinated waste plastic P4 was 22.3 wt%.

[0160] Comparative Example 1

[0161] The apparatus for pretreatment of PVC waste plastics as shown in Example 1 differs in that it does not contain a secondary separation device.

[0162] According to the method for pretreatment of PVC-containing waste plastics shown in Example 1, relatively light waste plastics and relatively heavy waste plastics are directly subjected to a first de-separation and a second de-separation, respectively, with the remaining steps being the same, to obtain dechlorinated waste plastics DS1 and chlorinated waste plastics DP1.

[0163] Among them, the chlorine content in dechlorinated waste plastic DS1 was 0.23 wt%, and the chlorine content in chlorinated waste plastic DP1 was 16.2 wt%.

[0164] Comparative Example 2

[0165] The apparatus for pretreatment of PVC waste plastics as shown in Example 1 is different in that the secondary separation equipment is replaced with a centrifugal separation equipment.

[0166] Following the method for pretreatment of PVC-containing waste plastics as shown in Example 1, the relatively lightweight waste plastics were centrifuged (8000 rpm for 10 min), and the remaining steps were the same, to obtain dechlorinated waste plastics DS2 and DP2.

[0167] The chlorine content in the dechlorinated waste plastic DS2 was 0.085 wt%, while the chlorine content in the chlorinated waste plastic DP2 was 21.5 wt%.

[0168] Compared to Comparative Example 1, using the separation equipment provided by this invention for the sedimentation separation of relatively lightweight waste plastics can further separate chlorine-containing waste plastics from relatively lightweight waste plastics, thereby effectively reducing the chlorine content in dechlorinated waste plastics. In particular, by limiting the structure of the separation equipment, such as the screw speed, the structure of the spiral blades, the projected length of the shell in the horizontal plane, and the height of the partition plate, it is more conducive to reducing the chlorine content in dechlorinated waste plastics, thereby effectively achieving the pretreatment of PVC-containing waste plastics.

[0169] Meanwhile, the method for pretreatment of PVC-containing waste plastics provided by the present invention can effectively separate the chlorine content in PVC-containing waste plastics, resulting in dechlorinated waste plastics with lower chlorine content and chlorinated waste plastics with higher chlorine content.

[0170] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for pretreatment of PVC-containing waste plastics, characterized in that, The method includes the following steps: (1) contacting PVC-containing waste plastics and a first separation fluid and centrifuging them to obtain centrifuged separation fluid, relatively light waste plastics and relatively heavy waste plastics, wherein the centrifugation conditions include: rotation speed ≥ 8000 rpm, the weight ratio of the PVC-containing waste plastics and the first separation fluid is 1:5-70, and the first separation fluid is selected from at least one of water, inorganic matter and organic matter; (2) in a separation device, contacting the relatively light waste plastics and the second separation fluid and sedimentation separation to obtain chlorine-rich waste plastics and dechlorinated waste plastics; (3) performing a first dechlorination separation on the dechlorinated waste plastics to obtain a first dechlorination separation fluid and dechlorinated waste plastics; (4) mixing the relatively heavy waste plastics and chlorine-rich waste plastics and performing a second dechlorination separation to obtain a second dechlorination separation fluid, solid impurities and chlorine-containing waste plastics; wherein the equivalent diameter of the PVC-containing waste plastics is 1-5 mm; The separation device includes: a housing having a communicating sedimentation separation zone and a product zone, and a screw propeller; the screw propeller includes: a motor and at least one screw, the screw being positioned near the bottom of the housing and penetrating into the interior of the sedimentation separation zone; the screw rotating at a speed of 15-30 rpm; the screw including a rotating shaft and helical blades disposed on the rotating shaft, the pitch of the helical blades being 10-300 mm; the closest distance from the outer diameter of the helical blades to the rotating shaft being 20-100 mm; the ratio of the length of the screw extending into the sedimentation separation zone to the length of the sedimentation separation zone being 0.5-0.9:1; the ratio of the length of the helical blades wound around the rotating shaft to the length of the screw extending into the sedimentation separation zone being 0.6-0.99:1; the projected length of the housing in the horizontal plane being 0.5-3 m; the ratio of the projected lengths of the sedimentation separation zone and the product zone in the horizontal plane being 3-10:1; The settling separation zone has a material inlet at the top and at least one separation fluid inlet on the side. The product zone has a heavy material outlet and a light material outlet, as well as a partition plate separating the heavy material outlet and the light material outlet. The height of the partition plate is higher than the upper edge of the screw, and the difference between the height of the partition plate and the upper edge of the screw is 0.5-50 cm. The motor drives the screw to rotate, so that the material passing through the material inlet and the separation fluid passing through the separation fluid inlet come into contact and settle in the separation and settling zone. The resulting heavy material and light material are led out through the heavy material outlet and the light material outlet, respectively, under the action of the screw.

2. The method according to claim 1, wherein, The number of the separation fluid inlets is ≥2.

3. The method according to claim 2, wherein, The number of the separation fluid inlets is 2-5.

4. The method according to claim 1, wherein, The number of screws is 1-2; And / or, the cross-section of the rotating shaft is circular and / or rectangular.

5. The method according to claim 4, wherein, The ratio of the length of the screw extending into the settling separation zone to the length of the settling separation zone is 0.7-0.9:1; And / or, the ratio of the length of the helical blade winding around the rotating shaft to the length of the screw extending into the settling separation zone is 0.7-0.99:1; And / or, the cross-section of the rotating shaft is circular.

6. The method according to claim 1, wherein, Along the material flow direction, the product zone is located below the sedimentation separation zone, and the bottom of the product zone is lower than the bottom of the sedimentation separation zone.

7. The method according to claim 6, wherein, The projected length of the shell in the horizontal plane is 1-3 m; And / or, the ratio of the projected lengths of the sedimentation separation zone and the product zone in the horizontal plane is 3-7:

1.

8. The method according to claim 1, wherein, The difference between the height of the partition plate and the upper edge of the screw is 5-10 cm.

9. The method according to claim 1, wherein, In step (1), the PVC content is 0.1-50 wt%, based on the total weight of the PVC-containing waste plastics. And / or, the conditions for centrifugation include: a time of 1-30 min.

10. The method according to claim 9, wherein, In step (1), the PVC content is 0.1-25 wt%, based on the total weight of the PVC-containing waste plastics. And / or, the conditions for centrifugation include: a time of 5-20 min.

11. The method according to claim 10, wherein, In step (1), the weight ratio of the PVC-containing waste plastic and the first separation fluid is 1:5-50.

12. The method according to claim 1, wherein, In step (2), the weight ratio of the relatively lightweight waste plastic and the second separated fluid is 1:10-100; And / or, the first separation fluid and the second separation fluid are each independently selected from at least one of water, inorganic matter and organic matter.

13. The method according to claim 12, wherein, In step (2), the weight ratio of the relatively lightweight waste plastic and the second separated fluid is 1:20-50; And / or, based on the total weight of the first separated fluid / second separated fluid, the water content is 0-100 wt%, the inorganic content is 0-50 wt%, and the organic content is 0-50 wt%; And / or, the inorganic substance is a soluble compound; And / or, the organic compound is selected from at least one of nonpolar organic compounds, nonpolar organics, and surfactants.

14. The method according to claim 13, wherein, Based on the total weight of the first separated fluid / second separated fluid, the water content is 90-100 wt%, the inorganic content is 0-15 wt%, and the organic content is 0-15 wt%. And / or, the inorganic substance is selected from at least one of sodium chloride, calcium chloride, sodium nitrate, sodium hydroxide, and potassium hydroxide; And / or, the nonpolar organic compound is selected from at least one of acetone, tetrabromoethane, ethanol, ethylene glycol and glycerol; the polar organic compound is selected from at least one of methanol, ethanol, tetrahydrofuran and DMF; and the surfactant is selected from at least one of sulfated oil, higher fatty alcohol sulfates and sodium dodecylbenzenesulfonate.

15. The method according to claim 1, wherein, The method further includes: recovering the centrifugally separated fluid as a circulating separated fluid; And / or, the method further includes: independently recovering the first and second deseparated fluids as circulating separation fluids; And / or, the method further includes: collecting the solid impurities.

16. An apparatus for pretreating PVC-containing waste plastics, characterized in that, The method described in any one of claims 1-15 is carried out in the apparatus, which includes: a waste plastic silo, a primary separation device, a secondary separation device, a first de-separation device, and a dechlorinated waste plastic tank connected in sequence, and a second de-separation device and a chlorinated waste plastic tank connected in sequence with the primary separation device; The waste plastic bin is used to introduce PVC-containing waste plastic into the primary separation equipment; The primary separation equipment is used to contact the PVC-containing waste plastic and the first separation fluid and centrifuge them to obtain centrifuged separation fluid, relatively light waste plastic and relatively heavy waste plastic; The secondary separation device is connected to the relatively light waste plastic outlet of the primary separation device, and is used to contact the relatively light waste plastic and the second separation fluid for sedimentation separation to obtain dechlorination-rich waste plastic and chlorine-rich waste plastic; The first separation device is connected to the outlet of the dechlorination-rich waste plastic of the secondary separation device, and is used to perform a first separation of the dechlorination-rich waste plastic to obtain a first separation fluid and dechlorination waste plastic; The dechlorination waste plastic tank is connected to the dechlorination waste plastic outlet of the first dechlorination separation equipment and is used to store the dechlorination waste plastic; The second separation device is connected to the outlet of the relatively heavy waste plastic of the first separation device, and is used to perform a second separation of the relatively heavy waste plastic to obtain a second separation fluid, solid impurities and chlorine-containing waste plastic; The chlorine-containing waste plastic tank is connected to the chlorine-containing waste plastic outlet of the second separation device and is used to store the chlorine-containing waste plastic.

17. The apparatus according to claim 16, wherein, The outlet of the chlorine-rich waste plastic in the secondary separation device is connected to the inlet of the second de-separation device, and is used to return the chlorine-rich waste plastic and mix it with the relatively heavy waste plastic. And / or, the apparatus further includes: a fluid recovery tank connecting the primary separation unit and the secondary separation unit; And / or, the centrifugal separation fluid outlet of the primary separation device is connected to the fluid recovery tank for recycling the centrifugal separation fluid as a circulating separation fluid; And / or, the first deseparation fluid outlet of the first deseparation device is connected to the fluid recovery tank for recycling the first deseparation fluid as a circulating separation fluid; And / or, the second separation fluid outlet of the second separation device is connected to the fluid recovery tank for recycling the second separation fluid as a circulating separation fluid.

18. The apparatus according to claim 16 or 17, wherein, The device further includes: a solid impurity collection tank connected to the solid impurity outlet of the second separation device, for collecting the solid impurities; And / or, the apparatus further includes: a first conveying device connecting the relatively light waste plastic outlet of the primary separation unit and the secondary separation unit; And / or, the apparatus further includes: a second conveying device connected to the relatively heavy waste plastic outlet of the primary separation device and the second de-separation device; And / or, the device further includes a third conveying device connecting the waste plastic bin and the primary separation equipment.

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