Waste plastic-based artificial aggregate manufacturing method and its manufacturing apparatus

Abstract

The present invention relates to a method for manufacturing artificial aggregate based on waste plastic and an apparatus for manufacturing the same. More specifically, the invention relates to a method for manufacturing artificial aggregate based on waste plastic and an apparatus for manufacturing the same, wherein waste plastic is recycled to produce an environmentally friendly artificial aggregate, and waste plastic is mixed with fly ash, glass fiber, crushed fiber, and biochar with a stabilizer and an antifoaming agent to effectively prevent oxidation of the artificial aggregate and provide flame retardancy. The technical gist of the present invention is that a method for manufacturing artificial aggregate based on waste plastic and an apparatus for manufacturing the same, for achieving the above-mentioned purpose, comprises: a raw material preparation step in which waste plastic is collected, classified, washed, and crushed to obtain a primary raw material; a stirring step in which the primary raw material obtained in the raw material preparation step is processed and mixed to obtain a secondary raw material; a molding step in which the secondary raw material stirred in the stirring step is formed into an aggregate shape; and an inspection step in which the secondary raw material formed into an aggregate shape in the molding step is inspected according to predetermined conditions to determine whether it is to be used, wherein the secondary raw material is a mixture of 40 to 50 wt% of the primary raw material, 10 to 20 wt% of fly ash, 10 to 20 wt% of glass fiber, 5 to 10 wt% of crushed fiber, 5 to 10 wt% of biochar, 1 to 2 wt% of stabilizer, and 0.1 to 1 wt% of defoamer, and in the inspection step, the compressive strength, water absorption rate, permeability, density, and specific gravity of the aggregate are inspected.

Description

Technology Field

[0001] The present invention relates to a method for manufacturing artificial aggregate based on waste plastic and an apparatus for manufacturing the same. More specifically, the invention relates to a method for manufacturing artificial aggregate based on waste plastic and an apparatus for manufacturing the same, wherein waste plastic is recycled to produce an environmentally friendly artificial aggregate, and waste plastic is mixed with fly ash, glass fiber, crushed fiber, and biochar with a stabilizer and an antifoaming agent to effectively prevent oxidation of the artificial aggregate and provide flame retardancy. Background Technology

[0002] In modern society, plastic products are widely used in various industrial fields due to their advantages such as lightweightness, chemical resistance, and cost-effectiveness.

[0003] However, environmental pollution is emerging as a serious problem due to the increase in plastic waste, and research on plastic recycling and effective disposal methods is continuously being conducted.

[0004] In particular, waste plastics are difficult to decompose naturally and can persist in the environment for a long time, potentially causing soil and air pollution when landfilled or incinerated. Furthermore, existing waste plastic recycling methods suffer from problems such as reduced thermal stability and weakened mechanical properties during repetitive processing.

[0005] Accordingly, existing waste plastic-based products have limitations, such as low durability, insufficient impact resistance, and restricted use in specific applications.

[0006] Furthermore, plastics are inherently highly flammable, leading to rapid combustion and the potential release of toxic gases in the event of a fire, making the improvement of flame retardancy a critical challenge.

[0007] In particular, when used as construction and civil engineering materials, materials lacking flame retardancy can cause safety issues. Although various flame retardant additives are being researched to improve this, there is a lack of technology that simultaneously satisfies economic efficiency and environmental friendliness.

[0008] In addition, when manufacturing artificial aggregates using waste plastics, it is difficult to secure sufficient physical strength through simple recycling methods alone, and there is a disadvantage in that compressive strength and durability are lower compared to conventional concrete aggregates.

[0009] Accordingly, there is a growing need for a method to manufacture plastic-based artificial aggregates that are environmentally friendly, possess excellent physical properties, and have thermal stability and flame retardancy by effectively recycling waste plastics. Prior art literature

[0010] (Patent Document 0001) KR 10-2120445 B1(Patent Document 0002) KR 10-2585106 B1 The problem to be solved

[0011] The present invention was developed to resolve the above-mentioned problems, and aims to provide a method for manufacturing artificial aggregate based on waste plastic and an apparatus for manufacturing the same, which is environmentally friendly as the artificial aggregate is produced by recycling waste plastic, and provides excellent physical properties by mixing fly ash, glass fiber, crushed fiber, and biochar as reinforcing materials, and effectively prevents oxidation of the artificial aggregate and provides flame retardancy by mixing calcium, which provides thermal stability of plastic molded products, phosphoric acid, which prevents oxidation, and aluminum hydroxide, which provides flame retardancy, as stabilizers.

[0012] The objectives of the present invention are not limited to those mentioned above, and other unmentioned objectives would have been clearly understood from the description below. means of solving the problem

[0013] The present invention, for achieving the above-mentioned purpose, includes a method for manufacturing artificial aggregate based on waste plastic and an apparatus for manufacturing the same, wherein waste plastic is collected, classified, washed, and crushed to obtain a primary raw material; a stirring step in which the primary raw material obtained in the raw material preparation step is processed and mixed to obtain a secondary raw material; a molding step in which the secondary raw material stirred in the stirring step is formed into an aggregate shape; and an inspection step in which the secondary raw material formed into an aggregate shape in the molding step is inspected according to predetermined conditions to determine whether it is to be used, wherein the secondary raw material is a mixture of 40 to 50 wt% of the primary raw material, 10 to 20 wt% of fly ash, 10 to 20 wt% of glass fiber, 5 to 10 wt% of crushed fiber, 5 to 10 wt% of biochar, 1 to 2 wt% of stabilizer, and 0.1 to 1 wt% of defoamer, and wherein the compressive strength, water absorption rate, permeability, density, and specific gravity of the aggregate are inspected in the inspection step.

[0014] In addition, the above-mentioned defoaming agent is characterized by being a mixture of polydimethylsiloxane and silicon dioxide.

[0015] In addition, the technical feature of the above stabilizer is that calcium, phosphoric acid, and aluminum hydroxide are used.

[0016] In addition, the device used for producing waste plastic-based artificial aggregate according to the present invention is characterized by the technical features comprising: a stirring unit that is stirred at a speed of 200 to 500 RPM at 150 to 300 ℃; an injection unit connected to and positioned on one side of the stirring unit, wherein injection is performed at 200 to 300 ℃; a cutting unit positioned on one side of the injection unit, which is equipped with a cutting function by rotation; and a discharge unit positioned on one side of the cutting unit, which is formed in a shape that is wider at the top and narrower at the bottom.

[0017] In addition, the above stirring unit includes a paddle-type stirrer or a planet-type stirrer, and is characterized by the technical feature that the RPM speed can be adjusted. Effects of the invention

[0018] The present invention based on the above-described configuration can expect the following effects.

[0019] Since waste plastic is collected and recycled from discarded plastic packaging, bottles, and containers, it becomes possible to produce eco-friendly artificial aggregates.

[0020] Fly ash, glass fiber, crushed fiber, and biochar are added as fillers, resulting in excellent compressive strength, low water absorption, and permeability, which enables the realization of superior physical properties as an artificial aggregate.

[0021] Calcium for thermal stability of the plastic, phosphoric acid for oxidation prevention, and aluminum hydroxide for flame retardancy are mixed as stabilizers, making it possible to effectively prevent oxidation of the artificial aggregate and provide flame retardancy.

[0022] The rotational speed of the rotary carbon steel cutter is adjusted, making it possible to manufacture artificial aggregate in the form of fillets of a desired length. Brief explanation of the drawing

[0023] FIG. 1 is a flowchart of a method for manufacturing waste plastic-based artificial aggregate according to a preferred embodiment of the present invention. FIG. 2 is a flowchart of the stirring step of a method for manufacturing waste plastic-based artificial aggregate according to a preferred embodiment of the present invention. FIG. 3 is a flowchart of the molding step of a method for manufacturing waste plastic-based artificial aggregate according to a preferred embodiment of the present invention. FIG. 4 is a configuration diagram of a waste plastic-based artificial aggregate manufacturing device according to a preferred embodiment of the present invention. FIG. 5 is a diagram showing the configuration of the stirring section and the injection section of a waste plastic-based artificial aggregate manufacturing device according to a preferred embodiment of the present invention. Specific details for implementing the invention

[0024] A negative pressure ward isolation room system according to a preferred embodiment of the present invention will be described in detail below with reference to the attached drawings.

[0025] FIG. 1 is a flowchart of a method for manufacturing artificial aggregate based on waste plastic according to a preferred embodiment of the present invention, FIG. 2 is a flowchart of a stirring step of a method for manufacturing artificial aggregate based on waste plastic according to a preferred embodiment of the present invention, FIG. 3 is a flowchart of a molding step of a method for manufacturing artificial aggregate based on waste plastic according to a preferred embodiment of the present invention, and FIG. 4 is a configuration diagram of a device for manufacturing artificial aggregate based on waste plastic according to a preferred embodiment of the present invention.

[0026] The method for manufacturing artificial aggregate based on waste plastic according to a preferred embodiment of the present invention may consist of a raw material preparation step (S100), a stirring step (S200), a molding step (S300), and an inspection step (S400), as illustrated in FIG. 1.

[0028] First, let's look at the above raw material preparation step (S100).

[0029] The raw material preparation step (S100) can be a step in which waste plastic is collected, classified, washed, and crushed to obtain primary raw materials.

[0030] More specifically, after waste plastic is collected from discarded plastic packaging, bottles, and containers, it may be possible to classify the waste plastic according to the types of PP, PE, PET, and PVC.

[0031] Waste plastics classified according to the type of plastic can be washed with high-pressure water and crushed into particles of 1 to 10 mm in size to obtain primary raw materials.

[0033] Next, we will examine the above stirring step (S200).

[0034] The stirring step (S200) may be a step in which a filler, a stabilizer, and an antifoaming agent are mixed with the primary raw material obtained in the raw material preparation step (S100) to obtain a secondary raw material.

[0035] In detail, it may be possible to obtain a secondary raw material by mixing 40 to 50 wt% of the primary raw material, 10 to 20 wt% of fly ash, 10 to 20 wt% of glass fiber, 5 to 10 wt% of crushed fiber, 5 to 10 wt% of biochar, 1 to 2 wt% of stabilizer, and 0.1 to 1 wt% of defoamer.

[0036] Fly ash, glass fiber, crushed fiber, and biochar can be used as fillers to improve the physical properties and increase the chemical stability of artificial aggregates.

[0037] Fly ash is a fine powder-like byproduct generated when coal is burned, and it may be composed of 40–60 wt% silicon dioxide (SiO₂), 15–30 wt% aluminum oxide (Al₂O₃), 5–10 wt% iron oxide (Fe₂O₃), 1–30 wt% calcium oxide (CaO), 1–5 wt% magnesium oxide (MgO), 0.5–5 wt% sulfur oxide (SO₃), and 0.5–3 wt% alkali components (Na₂O, K₂O).

[0038] In particular, the fly ash used in the stirring step (S200) of the present invention may be class F fly ash containing 1 to 10 wt% calcium oxide (CaO).

[0039] Class F fly ash has a low calcium carbonate (CaO) content, which reduces hydration reactions, thereby decreasing the expansion and deformation of the aggregate and making it possible to improve dimensional stability.

[0040] The stabilizer may be composed of calcium, phosphate, and aluminum hydroxide.

[0041] Specifically, it may be composed of 50-60 wt% calcium to provide thermal stability to the plastic, 20-30 wt% phosphoric acid to prevent oxidation of the artificial aggregate, and 10-20 wt% aluminum hydroxide to provide flame retardancy.

[0042] To prevent oxidation of artificial aggregates, 20 to 30 wt% of phosphoric acid is included, and more specifically, one or more of phosphoric acid esters including phosphoric acid (H₃PO₄) or tributyl phosphate (TBP), triethyl phosphate (TEP), and dimethyl phosphate (DMP) may be selected and used.

[0043] Tributyl Phosphate (TBP) prevents oxidation of artificial aggregates while acting as a plasticizer, so when mixed as a stabilizer, it may be possible to increase the flexibility of plastic-based artificial aggregates.

[0044] Triethyl Phosphate (TEP) prevents oxidation of artificial aggregates while acting as a flame retardant, so when mixed as a stabilizer, it may be possible to increase the flame retardancy of plastic-based artificial aggregates.

[0045] Dimethyl Phosphate (DMP) prevents oxidation of artificial aggregates while having low moisture absorption, so when mixed as a stabilizer, it may be possible to increase the moisture resistance of plastic-based artificial aggregates.

[0046] Silicone-based defoaming agents are used, but it is possible to use a mixture of polydimethylsiloxane (PDMS) and silicon dioxide (SiO₂).

[0047] Specifically, it may be possible to use a mixture of 90-95 wt% polydimethylsiloxane (PDMS) and 5-10 wt% silicon dioxide (SiO₂).

[0048] When silicon dioxide (SiO₂) is included in an amount of 5 wt% or less, the defoaming effect is reduced, and when it is included in an amount of 10 wt% or more, the viscosity of polydimethylsiloxane is increased, so it does not spread well in the foaming liquid, which may reduce the defoaming effect.

[0049] Since polydimethylsiloxane (PDMS)-based silicone defoamers have low dispersibility, silicon dioxide (SiO2) may be mixed to improve the dispersion effect, thereby increasing the dispersibility of the defoamer.

[0050] Due to the presence of silicon dioxide (SiO2) particles, polydimethylsiloxane-based silicone defoamers can spread rapidly in the fluid, which can improve the dispersion efficiency of silicone defoamers and increase the defoaming effect.

[0051] In addition, silicon dioxide (SiO2) can form a force that attacks bubbles due to its small particle size, large specific surface area, high surface energy, and three-dimensional mesh structure, so antifoaming agents containing it can achieve high efficiency and synergistic antifoaming effects.

[0052] In particular, the particle size of silicon dioxide (SiO2) is formed to be 5 to 8 μm, so that the silicon-based defoamer forms very small particles and a number of basic defoaming units in the foaming liquid, effectively penetrating the liquid film of the bubbles to burst the bubbles, and an excellent defoaming effect can be achieved.

[0053] If the particle size of silicon dioxide (SiO2) is less than 5 µm, they easily aggregate with each other due to high surface energy, resulting in uneven dispersion within the defoaming agent and reduced defoaming effect, and if it exceeds 8 µm, the penetration power of the bubbles into the liquid film decreases, which may lead to a reduction in the defoaming effect.

[0055] The stirring step (S200) may be divided into a melting process (S210), a first mixing process (S220), and a second mixing process (S230).

[0057] The melting process (S210) may be a process of introducing the primary raw material obtained from the raw material preparation system into the stirring unit (100) to be described later and applying heat of 200 to 300°C to transform the primary raw material into a semi-liquid state.

[0058] The stirring speed can be set to 200 to 500 RPM, so that the primary raw material can be evenly stirred and melted.

[0059] To maintain optimal stirring, the RPM speed can be adjusted according to the situation, and as the melting process enters the latter part and the melting is nearing completion, it may be possible to gradually lower the RPM speed.

[0060] For example, it may be possible to start at 400 to 500 RPM and gradually decrease the stirring speed to 200 RPM to 300 RPM as the melting process (S210) enters the latter part.

[0061] Through this, stirring efficiency according to the change in viscosity of the primary raw material is maximized, and it is possible to ensure the uniformity of the final melt.

[0063] The first mixing process (S220) may be a process in which a stabilizer and an antifoaming agent are added to the first raw material that has been modified into a semi-liquid state, and mixed at a temperature of 140 to 160°C at a speed of 200 to 300 RPM for 15 to 20 minutes.

[0064] A stabilizer is a substance added to improve the thermal stability of plastics, and by adding it while the primary raw material is in a molten state, it can be uniformly dispersed in the molten plastic matrix, making it possible to effectively prevent thermal decomposition.

[0065] The defoaming agent is a substance added to remove bubbles generated during plastic processing, and it may be possible to maximize the defoaming effect by acting directly on the area where bubbles are formed as the primary raw material melts.

[0066] In addition, the silicon-based defoamer mixed with silicon dioxide (SiO2) in polydimethylsiloxane (PDMS) has relatively high compatibility, so it can be effectively dispersed even under low shear force conditions caused by reduced stirring speed in the latter part of the melting process (S210), thereby making it possible to reduce process costs.

[0067] Stabilizers and defoamers can be prevented from being thermally damaged while being stirred at a low temperature of 140 to 160°C.

[0069] In the second mixing process (S230), after the first mixing process (S220) is completed, fly ash, glass fiber, crushed fiber, and biochar may be mixed at a temperature of 140 to 160°C at a speed of 200 to 300 RPM for 15 to 20 minutes to obtain a second raw material.

[0070] If the defoaming agent is added after the addition of the filler, the dispersion of the defoaming agent may become uneven depending on the physical properties of the filler, which may lead to a decrease in the defoaming effect. Therefore, it may be possible to add the defoaming agent in the first mixing process (S220) to effectively remove bubbles generated during the plastic melting process (S210), and then add the filler in the second mixing process (S230).

[0071] Fly ash, glass fiber, shredded fiber, and biochar used as fillers may each exhibit physical properties that can reduce the dispersion of the defoaming agent.

[0072] These fillers generally have a porous structure, which can affect the uniform dispersion of the defoamer, such as by causing the defoamer to be adsorbed within the pores or existing in the form of long, thin fibers that hinder the dispersion of the defoamer.

[0074] Next, we will examine the forming step (S300).

[0075] The molding step (S300) may be a step in which the secondary raw material stirred in the stirring step (S200) is formed into an aggregate shape.

[0076] More specifically, it may be composed of an injection process (S310), a cutting process (S320), and a cooling process (S330).

[0078] The injection process (S310) may be a process in which the secondary raw material, after the stirring step (S200) is completed, is fed into the injection unit (200) described later, and then compressed and injected into the form of long pellets by a screw (220) at 200 to 300°C.

[0079] In the above secondary mixing process (S230), the secondary raw material stirred at 140 to 160°C is injected at a high temperature of 200 to 300°C, thereby increasing the fluidity of the secondary raw material and making it possible for the injection process (S310) to proceed smoothly.

[0080] The diameter of the injected aggregate can be set to 20 to 30 mm for coarse aggregate and 5 to 20 mm for fine aggregate, so that it can be injected according to the set diameter.

[0081] When injecting coarse aggregate with a fillet diameter of 20 to 30 mm, an injection pressure of about 60 to 100 MPa may be set, and when injecting fine aggregate with a fillet diameter of 5 to 20 mm, an injection pressure of about 100 to 150 MPa may be set.

[0082] High temperature and pressure conditions within the aforementioned range can increase the density of the fillets and reduce internal voids, thereby making it possible to improve the strength and durability of the artificial aggregate.

[0083] Additionally, it may be possible to control the injection speed to improve the surface roughness of the artificial aggregate.

[0084] During high-speed injection, the surface of the plastic may deform, resulting in a rough appearance or the formation of wavy patterns, which can improve the surface roughness.

[0085] Since plastic-based artificial aggregates have a smooth surface and low adhesion to cement, it may be possible to increase adhesion to cement by improving surface roughness through adjusting the injection speed to compensate for this.

[0086] The injection speed may be set in the range of 3 to 6 m / min, and if it is set to 6 m / min or less, the secondary material is not heated sufficiently, resulting in low fluidity, making injection difficult, and it may be difficult to obtain a uniform surface roughness.

[0088] The cutting process (S320) may be a process in which the secondary raw material, which is injected in the form of a long pellet by the cutting part (300) described later, is delivered in a certain length.

[0090] The cooling process (S330) may be a process in which the secondary raw material, after the injection process (S310) is completed, is rapidly cooled.

[0091] The method for cooling is not limited, but rapid cooling may be possible using air cooling, water cooling, or a combination of both methods.

[0092] For example, the secondary raw material injected in the form of long pellets in the injection process (S310) may be cooled first before being cut in the cutting process (S320) by an air cooling method using a blower such as a fan blower, and at this time, the temperature of the cooling air may be set to a range of 10 to 25℃.

[0093] Afterwards, the secondary raw material, which is cut and formed into an aggregate shape, may be dropped into a tank filled with circulating cooling water at 25 to 40°C to be cooled a second time.

[0094] The secondary raw material formed in the form of aggregate may be immersed in cooling water for a certain period of time and then cooled to a target temperature.

[0096] Next, we will examine the inspection step (S400).

[0097] The inspection step (S400) may be a step in which the secondary raw material, which has been molded into an aggregate form in the molding step, is inspected according to preset conditions to determine whether it is to be used.

[0098] In detail, in order to inspect the durability of the secondary raw material that has been molded into an aggregate form in the molding step (S300), it may be possible to determine whether to use it by inspecting the compressive strength, water absorption rate and permeability, density, and specific gravity according to preset conditions.

[0100] Experimental Example 1. Evaluation of Physical Properties

[0101] To confirm the physical properties of the waste plastic-based artificial aggregate according to the method for manufacturing waste plastic-based artificial aggregate according to a preferred embodiment of the present invention, compressive strength, water absorption rate and permeability, density, and specific gravity were measured according to the measurement methods of heavy aggregate KS F 2503 and light aggregate KS F 2504, respectively, and the results are shown in Table 1.

[0103] Test items Measured values ​​of developed artificial aggregate requirements Compressive strength lightweight aggregate 20 MPa 10 MPa heavy aggregate 45 MPa 30 MPa Absorption rate and permeability lightweight aggregate 5% or less 10% or less heavy aggregate 5% or less 7% or less density lightweight aggregate 1.0~2.0 g / cm³ 1.0~2.0 g / cm³ heavy aggregate 2.5~3.5 g / cm³ 2.5~3.5 g / cm³ specific gravity lightweight aggregate 1.0~2.0 1.0~2.0 heavy aggregate 2.5~3.0 2.5~3.0

[0105] Referring to Table 1, it can be seen that the waste plastic-based artificial aggregate according to a preferred embodiment of the present invention has excellent compressive strength, water absorption rate and permeability, density, and specific gravity that satisfy the requirements for both lightweight and heavyweight aggregates, and that desired physical properties can be achieved.

[0107] A waste plastic-based artificial aggregate manufacturing device according to a preferred embodiment of the present invention may be composed of a stirring unit (100), an injection unit (200), a cutting unit (300), and a discharge unit (400) as shown in FIG. 4.

[0109] First, let's look at the stirring unit (100).

[0110] The stirring unit (100) is composed of an inlet (110), a stirring tank (120), a stirrer (130), and an outlet (140), and the stirring step (S200) can be performed at a speed of 200 to 500 RPM at 150 to 300 ℃.

[0111] The input port (110) may be provided in multiple numbers at the top of the stirring tank (120), and may be composed of a primary raw material input port (111) into which a primary raw material is introduced and an additive input port (112) into which a supplement, stabilizer, and defoamer are introduced.

[0112] The mixing tank (120) is configured as a cylindrical shape with a conical bottom so that the internal mixture does not stagnate, and the conical and cylindrical shapes are smoothly connected in a streamlined manner so that the internal mixture can be smoothly mixed.

[0113] The stirring tank (120) of the above-described type can effectively prevent the formation of a dead volume, which is an area where the internal mixture does not move and remains stagnant.

[0114] The secondary raw material, after stirring is complete, may be moved to the injection unit (200) to be described later through the opening of the discharge port (140) located at the bottom of the stirring tank (120).

[0115] The discharge port (140) may be equipped with a gate valve or a screw feeder that can control the discharge speed so that a constant amount of secondary raw material can be supplied to the injection unit (200) described later.

[0116] The stirrer (130) is located inside the stirring tank (120), and it may be possible to use a paddle-type stirrer or a planet-type stirrer that is advantageous for medium-speed stirring.

[0117] The agitator (130) may be able to adjust the speed of the RPM manually or automatically depending on the situation.

[0119] Next, we will examine the injection part (200).

[0120] The injection unit (200) is connected to and positioned on one side of the stirring unit (100), and the molding step (S300) in which injection is performed at 200 to 300 ℃ may be performed.

[0121] The injection unit (200) may be composed of a heating cylinder (210), a screw (220), and a nozzle (230).

[0122] The heating cylinder (210) is equipped with a heater inside so that the internal temperature is uniformly maintained at 200 to 300 ℃, and the secondary raw material moved from the stirring unit (100) is heated so that fluidity can be ensured.

[0123] To optimize heat distribution, it may be possible to divide into multiple zones and position multiple heaters.

[0124] The screw (220) is positioned inside the heating cylinder (210), and it may be possible to induce the secondary raw material to gradually advance through rotation.

[0125] The L / D ratio and compression ratio of the screw (220) can be adjusted according to the characteristics of the injection material.

[0126] The nozzle (230) is located at the end of the heating cylinder (210), and it may be possible to inject secondary raw material advanced by the screw (220) inside the barrel.

[0128] Next, we examine the cutting section (300).

[0129] The cutting part (300) is located on one side of the injection part (200), and it may be possible to have a cutting function by rotation.

[0130] In detail, a rotary carbon steel cutter may be provided on one side of the injection unit (200) to cut the injected long fillet-shaped secondary raw material.

[0131] The cutting section (300) can adjust the length of the fillet-shaped secondary raw material by adjusting the speed of the rotary carbon steel cutter, and the faster the rotation speed, the shorter the length of the cut, and the slower the speed, the longer the length of the cut.

[0132] In a rotary carbon steel cutter, a double angle is applied to the blade, so that the first angle easily penetrates the secondary material and the second angle reduces cutting resistance, making it possible to cut the secondary material smoothly.

[0133] The first angle is designed to be 20 to 30 degrees and the second angle to be 40 to 50 degrees, so that the durability of the blade is improved while cutting efficiency is maximized.

[0134] If the first angle is formed to be less than 20 degrees, the blade may be easily damaged, and if it exceeds 30 degrees, the cut cross-section of the secondary material may be pressed and deformed during the cutting process (S320).

[0135] If the second angle is formed to be less than 40 degrees, the durability of the blade may be reduced, and if it exceeds 50 degrees, the cutting efficiency may be reduced.

[0136] In particular, the waste plastic-based artificial aggregate according to a preferred embodiment of the present invention has relatively high viscosity as it is based on waste plastic, so slippage may be prominent when cutting. However, a cutter with a double angle applied as described above can prevent slippage by allowing the blade to easily penetrate the secondary material through the first angle and reducing the cutting resistance through the second angle.

[0137] Additionally, rotary carbon steel cutters may be coated with diamond-like carbon (DLC) to reduce blade wear caused by friction and heat during the cutting of secondary materials and to extend their lifespan.

[0139] Next, we will examine the discharge section (400).

[0140] The discharge section (400) is located on one side of the cutting section (300) and is formed in a shape that is wider at the top and narrower at the bottom, so that the secondary raw material cut by the cutting section (300) can fall downward and be discharged.

[0141] The dropped secondary raw material may be dropped into a tank filled with circulating cooling water at 25 to 40°C and cooled a second time.

[0142] The inner surface of the discharge section is coated with a low-friction coating, so that secondary raw materials can fall smoothly without sticking to or stagnating on the surface.

[0143] In detail, a fluoropolymer (PTRE) having a low friction coefficient of 0.05 to 0.1 is coated, so that the secondary raw material can fall smoothly without sticking to or stagnating on the inner surface of the discharge part.

[0145] Based on the configuration described above, the operating state of the present invention is examined.

[0146] First, a raw material preparation step (S100) is made possible in which discarded waste plastic is collected, the waste plastic is classified according to the type of PP, PE, PET, and PVC, and then the classified waste plastic is washed with high-pressure water and crushed into particles of 1 to 10 mm in size.

[0147] The primary raw material prepared through the above raw material preparation step (S100) is stirred together with a supplement, stabilizer, and antifoaming agent through the stirring step (S200) to produce a secondary raw material.

[0148] After the melting process (S210) in which the above primary raw material is introduced into the stirring unit (100) and melted by applying heat of 200 to 300°C, a primary mixing process (S220) in which a stabilizer and an antifoaming agent are added to the melted primary raw material, and a secondary mixing process (S230) in which a filler is added can be sequentially carried out.

[0149] The melting process (S210) can start at 400 to 500 RPM, and as the melting process (S210) enters the latter part, the stirring speed can be gradually reduced to 200 RPM to 300 RPM.

[0150] When the melting process (S210) is completed, a stabilizer and an antifoaming agent are introduced from an additive inlet (112) located on the other side of the primary raw material inlet (111), and can be mixed at a temperature of 140 to 160°C at a speed of 200 to 300 RPM for 15 to 20 minutes.

[0151] When the first mixing process (S220) is completed, a supplement is introduced from the additive inlet (112) and mixed for 15 to 20 minutes at a temperature of 140 to 160°C at a speed of 200 to 300 RPM through a second mixing process (S230), thereby making it possible to obtain a second raw material.

[0152] The above-mentioned stirred secondary raw material can be compressed and injected into a long fillet shape through the molding step (S300).

[0153] In the above secondary mixing process (S230), the secondary raw material, which has been stirred at 140 to 160°C, is compressed and injected at 200 to 300°C by the heating cylinder (210) of the injection unit (200) in the molding stage, thereby enabling the injection process (S310) to proceed with fluidity secured.

[0154] The injected secondary raw material is cut to a certain length by the rotation of the cutting part (300), and it is possible to cut to a shorter length as the rotation speed is set faster and to a longer length as the speed is slower, and this cutting process (S320) can be carried out by a rotary carbon steel cutter having a blade with a double angle applied as shown in FIG. 2.

[0155] After the cutting of the secondary raw material is completed, it is possible to determine whether it is to be used by inspecting it according to preset conditions through the inspection step (S400) after the cooling process (S330).

[0157] The above-described embodiments are merely exemplary, and various other modified embodiments are possible therefrom for those skilled in the art.

[0158] Therefore, the true technical scope of protection of the present invention must include not only the above embodiments but also other embodiments that are variously modified according to the technical concept of the invention described in the following claims. Explanation of the symbols

[0159] S100: Raw material preparation stage S200: Stirring step S210: Melting process S220: 1st mixing process S230 : Secondary mixing process S300: Molding stage S310: Injection molding process S320: Cutting process S330: Cooling process S400: Inspection stage 100 : Stirring part 110 : Input port 111 : Primary raw material input port 112 : Additive inlet 120 : Mixing tank 130 : Stirrer 140 : Outlet 200 : Injection part 210 : Heating cylinder 220 : Screw 230 : Nozzle 300 : Cutting section 400 : Discharge part

Claims

Claim 1 A raw material preparation step in which waste plastic is collected, classified, washed, and crushed to obtain a primary raw material; a stirring step in which the primary raw material obtained in the raw material preparation step is processed and mixed to obtain a secondary raw material; and a molding step in which the secondary raw material stirred in the stirring step is formed into an aggregate shape. and an inspection step in which the secondary raw material, which has been molded into an aggregate form in the molding step, is inspected according to preset conditions to determine whether it is to be used; wherein the secondary raw material comprises 40 to 50 wt% of the primary raw material, 10 to 20 wt% of fly ash, 10 to 20 wt% of glass fiber, 5 to 10 wt% of crushed fiber, 5 to 10 wt% of biochar, 1 to 2 wt% of stabilizer, and 0.1 to 1 wt% of defoamer, and the fly ash comprises 40 to 60 wt% silicon dioxide (SiO₂), 15 to 30 wt% aluminum oxide (Al₂O₃), 5 to 10 wt% iron oxide (Fe₂O₃), 1 to 10 wt% calcium oxide (CaO), 1 to 5 wt% magnesium oxide (MgO), 0.5 to 5 wt% sulfur oxide (SO₃), and 0 wt% alkali component.Class F fly ash composed of 5~3 wt% is used, and the defoamer is used by mixing 90~95 wt% of polydimethylsiloxane and 5~10 wt% of silicon dioxide, wherein the particle size of the silicon dioxide is formed to be 5 to 8 µm, and the stirring step comprises: a melting process in which the primary raw material obtained in the raw material preparation step is melted; and a primary mixing process in which the stabilizer and the defoamer are simultaneously added to and mixed with the primary raw material melted in the melting process. A method for producing artificial aggregate based on waste plastic, comprising a second mixing process in which the fly ash, glass fiber, crushed fiber, and biochar are mixed to obtain the second raw material after the first mixing process is completed, wherein the stabilizer is composed of 50-60% by weight of calcium, 20-30% by weight of phosphoric acid or phosphate ester, and 10-20% by weight of aluminum hydroxide, wherein the phosphate ester includes one or more of tributyl phosphate, triethyl phosphate, and dimethyl phosphate, and wherein in the inspection step, the compressive strength, water absorption rate, permeability, density, and specific gravity of the aggregate are all inspected to determine whether it is suitable for use. Claim 2 delete Claim 3 delete Claim 4 delete Claim 5 delete

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