The Current Status and Development Trend of Resourcing Technologies for Recyclable Materials
With the widespread implementation of garbage sorting and people's increasing emphasis on environmental protection and sustainable development, the resourcing of recyclable materials has become increasingly important. The resourcing of recyclable materials can not only reduce the adverse effects on the environment caused by improper disposal, but also bring many social and economic benefits. This article will review the current status of typical resourcing technologies for recyclable materials and look forward to the development direction of these technologies.
1. Typical resourcing technologies for recyclable materials
Recyclable materials mainly include five categories: waste plastics, waste textiles, waste glass, waste paper, and waste metals. Among them, the resourcing technologies for waste glass and waste paper have formed relatively complete industrial chains, conventional waste metals have also been well applied through re-smelting, and the recycling of rare and precious metals has become a focus of attention. High-quality waste plastics can be well utilized through recycling and high-quality waste textiles can be well utilized through circular reuse. Therefore, the resourcing of low-value waste plastics and waste textiles has become a focus of the industry's attention.
1.1 Resourcing technologies for waste plastics
Low-value recyclable waste plastic mainly includes takeout containers and express packaging materials, etc. The raw materials are basically polyolefins, mainly including polypropylene (PP), low-density polyethylene (LDPE), high-density polyethylene (HDPE), and polystyrene (PS). Polyolefin waste plastics PP, PE, and PS account for 92% of the total amount of plastic products, of which PP accounts for 28%, LDPE and HDPE account for 46%, and PS accounts for 18%. Currently, there are mainly three ways of dealing with waste plastics: physical recycling, chemical recycling, and energy utilization (mainly incineration).
1.2 Resourcing technologies for waste textiles
Waste textiles are mainly divided into polyester, cotton, blended, and other materials. Currently, the most common methods of processing include the following four: First, recycling in the form of second-hand clothing, which is generally more common in economically developed areas; second, direct landfilling, which is currently used by most waste textiles, but this method has problems such as polluting groundwater sources. Third, recycling and reuse, recycling and reuse methods mainly include energy methods, mechanical methods, physical methods, and chemical methods. Currently, cotton fibers, polyester fibers, and polyester-cotton blended fibers are the most consumed in textile products, and it is important to utilize them for resourcing purposes.
1.3 Resourcing technologies for waste paper
Waste paper can be divided into corrugated boxes, books and magazines, old newspapers, edge materials from paper box factories, white paper trimmings from printing factories, cement bags, mixed waste paper, and miscellaneous waste paper according to their sources. The main use of waste paper is for paper recycling. The waste paper recycling process mainly includes crushing, impurity removal, screening, and pulp preparation. The technology for recycling high-value waste paper is already quite mature.
1.4 Resourcing technologies for waste glass
The main ways to utilize waste glass include recycling, casting flux, transformation, material recovery, and reuse, among which recycling is the most common method. Before recycling waste glass, it needs to undergo complex preprocessing processes such as impurity removal, screening, sorting, cleaning, and drying to meet the requirements for recycling and then undergo melting and regeneration.
1.5 Resourcing technologies for waste metals
Common metal waste that enters the municipal solid waste collection and transportation system includes metal bottles and cans (such as aluminum cans and food cans/drums), metal kitchenware (such as knives and pots), metal tools (such as blades, nail clippers, and screwdrivers), metal products (such as nails, sheet metal, and aluminum foil), etc. Typical metal recycling processes mainly include mechanical processing, chemical treatment, and smelting.
2. Development trend of resourcing technologies for recyclable materials
2.1 Diversification and high-value utilization have become important trends.
With the advancement of technology and increased environmental awareness, the diversification and high-value utilization of recyclable materials have received increasing attention. However, some traditional methods of resourcing have difficulty fully utilizing the recyclable material attributes. Therefore, by comprehensively considering the resource attributes of recyclable materials and the demand for resource-based products, maximizing the high-value utilization of recyclable materials through diversified approaches has become an important trend in the resourcing of recyclable materials.
2.2 The low-carbon resourcing technologies for the entire lifecycle has become a key development direction.
With "dual carbon" becoming a national strategy, the carbon emissions of resourcing of recyclable materials have become a focus of attention in the industry, and the focus of attention has gradually shifted from the carbon emissions of a single link and a single technology to the carbon emissions of the entire process and entire lifecycle. Therefore, resourcing technologies with low process energy consumption and good substitution benefits for carbon reduction will become important directions for future development, such as the production of fiber-reinforced plastic sheets from low-value waste plastic and waste fabrics, and the production of oil through the pyrolysis of low-value waste plastic.