What Methods Can Be Used to Recycle Plastics?

Plastic recycling may seem complex, but its core objectives are twofold: reducing environmental pollution and reusing petroleum resources to avoid waste.

The specific processing method depends mainly on the type of plastic, its level of soiling, and its final use. Based on these factors, mainstream recycling methods can be divided into three main categories: physical recycling, chemical recycling, and energy recovery.

Let’s discuss the specific operations of each of these methods below.

Category 1: Physical Recycling

This is currently the most common and mainstream method. Simply put, it involves using mechanical means to process waste plastics into reusable raw materials.

Classification and Sorting

💡Manual sorting

Workers watch the conveyor belt and manually sort and classify plastic bottles according to the material number on the bottom (e.g., PET #1, HDPE #2). While slow, this method is more flexible when handling mixed waste with complex compositions.

💡Automatic sorting

Large recycling plants now commonly use technologies like near-infrared spectroscopy and lasers. As soon as the plastic passes through, the machine instantly identifies the material and automatically blows it into the corresponding bin using a high-pressure air gun, resulting in much higher efficiency and accuracy.

Washing and Crushing

♻️The sorted plastics are washed to remove labels, residues, dust, and adhesives.

♻️The plastics are then crushed into small pieces or granules using a crusher.

Granulation

♻️Cleaned plastic scraps are heated and melted, then extruded into strips using an extruder. After cooling, they are cut into recycled granules. These granules, like virgin material, can be sold to plastic product manufacturers to produce new products (such as garbage bags, plastic pipes, clothing fibers, etc.).

Category 2: Chemical Recycling

When physical recycling fails (e.g., plastics are too dirty, have multiple layers of composite packaging, or are severely aged), chemical recycling offers a deeper solution. It works by altering the chemical structure of the plastic, reducing it to its original chemical composition.

Pyrolysis

💡Principle: Breaking the long polymer chains of plastics under high-temperature, oxygen-free or oxygen-deficient conditions.

Products: Plastic oil (which can be refined into oil), syngas (which can be burned to generate electricity), and a small amount of residue.

Applications: Particularly suitable for processing mixed plastics or plastics that are difficult to clean.

Depolymerization

💡Principle: For specific plastics (such as nylon, polyurethane, PET), chemical reagents are used to decompose them into their original monomers.

Product: Pure chemical monomers are obtained, which can be directly repolymerized into plastics with quality almost identical to virgin plastics.

Gasification

💡Principle: Converting plastics into syngas at high temperatures.

Product: Syngas can be used for power generation or as a feedstock for the production of chemicals such as methanol.

Category 3: Energy Recovery

If plastic cannot be recycled through the above two methods (e.g., it is severely contaminated with hazardous substances or mixed with inseparable composite materials), converting it into energy is the last option.

Waste-to-Energy Incineration

💡Principle: Plastics are derived from petroleum and natural gas and have a high calorific value. Waste-to-energy incineration plants use plastics as fuel for combustion.

✅Advantages: Significantly reduces waste volume (approximately 90%) and generates electricity from the resulting heat.

❌️Disadvantages: May produce harmful gases such as dioxins. Therefore, a highly efficient flue gas purification system is necessary, leading to higher costs.

No matter which method you prefer for recycling plastic, Gomine has the equipment to suit your needs. So if you’re already considering this, feel free to contact us! We’ll provide a solution tailored to your requirements.