KR-102964575-B1 - Method for recycling waste plastic containers of oil products through safe and efficient removal of oil and foreign substances

Abstract

The present invention relates to a method for recycling waste plastic containers of oil products in an economical and eco-friendly manner, and more specifically, to a method for recycling waste plastic containers of oil products characterized by comprising: a de-oiling step of coarsely crushing a plastic container that contained oil and then removing a portion of the adhered oil by a predetermined method; a washing step of removing residual oil by stirring the de-oiled crushed material in a water tank in which an additive is dissolved, so that high-density impurities are separated to the bottom of the tank and low-density impurities are separated to the surface of the water; a drying step of de-drying the washed crushed material; a wind-power classification step of classifying the dried crushed material by wind power; and a pelletizing step of subsequently extruding the crushed material to form pellets.

Inventors

• 김성배
• 서동현

Assignees

• 주식회사 도원

Dates

Publication Date

20260513

Application Date

20231129

Claims (7)

1. A de-oiling step of coarsely crushing a plastic container that contained oils and then removing a portion of the adhered oil by a predetermined method; A washing step in which the deoiled pulverized material is stirred in a tank in which additives are dissolved to remove residual oil, and high-density impurities are separated to the bottom of the tank and low-density impurities to the surface; A drying step for dewatering and drying the washed pulverized material; A wind classification step for classifying the dried crushed material by wind power; Next, a pelletizing step in which the above-mentioned crushed material is extruded into pellets; Includes, A method for recycling waste plastic containers of oil products, characterized by the application of a drying-sorting tank in which the above-mentioned drying step and wind sorting step are integrated, an upward airflow capable of sufficiently raising crushed material from the bottom is generated, and an airflow is generated from one side of the upper part at a predetermined height to the side.
2. In claim 1, Between the above wind power classification step and the pelletization step, A fine grinding step for finely grinding the above-mentioned crushed material classified by wind power; An electrostatic classification step for classifying the finely ground material by an electrostatic separation method; A method for recycling waste plastic containers of oil products, characterized by additionally including
3. In claim 2, The crushed material coarsely ground in the above de-oiling step has a maximum length of 30 to 70 mm, and A method for recycling waste plastic containers of oil products, characterized in that the finely crushed material obtained in the above-mentioned fine crushing step has a maximum length of 5 to 20 mm.
4. In claim 1 or 2, In the above washing step, the water treatment additive is, A method for recycling waste plastic containers of oil products, characterized by being one or more anionic surfactants selected from the group consisting of higher fatty acid soap, linear alkylbenzene sulfonate (LAS), α-olefin sulfonate (AOS), and alkyl ether sulfate ester (AES).
5. In claim 1 or 2, The above washing step is, A method for recycling waste plastic containers of oil products, characterized by comprising a first washing step of washing once or multiple times with water containing additives, and a second washing step of finally washing with water without additives.
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Description

Method for recycling waste plastic containers of oil products through safe and efficient removal of oil and foreign substances The present invention relates to a method for recycling waste plastic containers of oil products in an economical and environmentally friendly manner. It is reported that approximately 200 million liters of engine oil are used annually in Korea between 2021 and 2026, with about 70% of this being for passenger cars (Non-patent Literature 1). Considering that commercially available engine oils mainly have a capacity of 1 L and weigh about 0.5 kg, approximately 200 million plastic engine oil containers, or about 100,000 tons, are generated annually in Korea. Engine oil containers are manufactured from High-Density Polyethylene (HDPE), a material characterized by high density and rigidity that withstands external impacts and offers excellent chemical and weather resistance. While HDPE plastics generally have high recycling value, the reality is that engine oil containers are difficult to recycle or chemically because various viscous organic and inorganic compounds adhere to their inner and outer surfaces. Consequently, they are currently classified as hazardous waste and either landfilled or recycled as fuel (thermal recycling). As mentioned above, in addition to the characteristic of difficult-to-remove viscous oil components adhering to the surface, the container opening is strongly sealed with an aluminum-film composite cap—in addition to a screw cap—to prevent internal oil leakage even under shock or pressure during storage and distribution. Furthermore, a label made of paper or aluminum-film composite is attached to the outside of the container. Factors such as the difficulty in removing these composite caps and labels, and the fact that various metal fragments or impurities are recovered along with the containers due to the nature of their usage in auto repair shops, pose challenges to the recycling of engine oil containers. Registered Patent 10-0416042 presents a recycling method for waste lubricating oil containers comprising the steps of: crushing waste plastic containers and removing oil by high-speed centrifugation; supplying the crushed material to a tank containing a solvent and water; separating oil from the crushed material while conveying it along a conveying screw wrapped in a perforated cylindrical body; and washing the discharged crushed material. However, according to the aforementioned prior art, solvents that are harmful to the environment, expensive, and difficult to manage are used, and while oil is removed relatively well, there are still difficulties in removing composite caps, aluminum labels, or various metal fragments, vinyl, and paper materials that are inevitably included. FIGS. 1a and 1b are exemplary flowcharts of a method according to the present invention. Figure 2 is a photograph of the crushed material after the de-oiling step. Figures 3a and 3b are photographs taken after the first washing step and the second washing step, respectively. Figures 3c and 3d are photographs of foreign matter recovered from the bottom of the tank during the washing step and a portion of the recovered foreign matter classified, respectively. Figures 4a and 4b are photographs showing an example of a wind separation process and the resulting separated crushed material. Figures 5a and 5b show the pellets of the ground material washed and sorted in this way, and photographs of the experimental specimens prepared using them. Figure 5c is a graph of the DSC results of the fabricated experimental specimen. FIG. 5d is an engine oil container experimentally prepared by adding 20% recycled pellets according to the present invention. Fig. 6a is a photograph of the high-speed grinder used in the fine grinding stage. Fig. 6b is a photograph of the electrostatic separator used in the electrostatic separation stage. The present invention will be described in more detail below with reference to the attached drawings and preliminary experiments. However, these drawings and embodiments are merely examples to facilitate the explanation of the content and scope of the technical concept of the present invention, and the technical scope of the present invention is not limited or altered by them. It will be obvious to those skilled in the art that various modifications and changes are possible within the scope of the technical concept of the present invention based on these examples. As previously stated, the present invention relates to a method for recycling waste plastic containers of oil products, comprising: a de-oiling step of coarsely crushing a plastic container that contained oils and then removing a portion of the adhered oil by a predetermined method; a washing step of removing residual oil by stirring the de-oiled crushed material in a water tank in which an additive is dissolved, so that high-density impurities are separated to the bottom of the tank and low-density impurities are