In industrial sorting and waste treatment systems, air separators, based on aerodynamic principles, achieve the separation of light and heavy materials through controlled airflow, overcoming the shortcomings of traditional contact-type sorting equipment. They do not require direct contact with the materials and excel at handling lightweight, irregular, or easily abrasive materials, finding wide application in waste treatment, resource recycling, ore processing, and food processing. The following section has already analyzed their core applications and typical characteristics; here, we first clarify their key value across multiple industries to lay the groundwork for subsequent content.

In the field of industrial sorting and waste treatment, air separators, as a sorting device based on "aerodynamics," achieve efficient separation of light and heavy materials by creating a controlled airflow environment and utilizing the air resistance and buoyancy differences generated by variations in density, particle size, and shape. Compared to magnetic separators and drum screens, which rely on physical contact or aperture size screening, air separators do not require direct contact with the materials and are particularly adept at handling lightweight, loose, irregular, or easily abrasive materials, making them widely used in waste treatment, resource recycling, ore processing, and other industries. The following section will comprehensively analyze the practical value and technological advantages of air separators from two aspects: core applications and typical characteristics.

Core Applications of Air Separators: Covering Sorting Needs in Multiple Fields

The applications of air separators revolve around three core objectives: "separation of light and heavy components, removal of impurities, and purification of resources." Different industries, based on material characteristics and production needs, achieve differentiated sorting by adjusting airflow parameters (wind speed, wind pressure, airflow direction) and equipment structure, providing a guarantee for subsequent production or processing processes.

1. Waste Treatment: Facilitating "Reduction, Resource Utilization, and Harmlessness"

Waste treatment is the primary application area for air separators. For different components of municipal solid waste, construction waste, and industrial solid waste, air separators play a crucial role in "separation of light and heavy components," "extraction of recyclables," and "removal of hazardous impurities," making them core equipment in waste sorting lines.

In municipal solid waste treatment, air separators are mainly used for "extraction of lightweight recyclables" and "pre-treatment before incineration." On the one hand, after manual sorting to remove large debris and magnetic separation of magnetic metals, lightweight recyclable materials (density 0.3-0.8 g/cm³) such as plastics (plastic bags, beverage bottle fragments), paper (waste paper, cardboard box scraps), and textiles (old clothes) in household waste can be separated by a negative pressure suction air separator (wind speed 8-15 m/s). After collection, they can be sold to recycling companies after further manual sorting. Data from a municipal solid waste sorting center shows that the air separator achieves a 90% recycling rate for plastics and an 82% recycling rate for paper, recovering approximately 5 tons of lightweight materials daily and generating over 800,000 yuan in economic benefits annually. On the other hand, in the pretreatment of waste incineration, air separators can separate heavy, inert components (slag, small stones, glass fragments, density above 2.0 g/cm³) from municipal solid waste, reducing the amount of non-combustible materials entering the incinerator. This increases the combustible content of the incinerator feed from 60% to 80%, increases power generation per ton of waste by 20 kWh, and reduces slag production by 30%.

In construction waste treatment, air separators focus on "recycled aggregate purification." The recycled aggregate produced after crushing construction waste often contains lightweight impurities (density 0.1-0.6 g/cm³) such as plastic film, foam, and wood chips. These impurities reduce aggregate strength and affect subsequent applications. A horizontal air classifier (wind speed 10-14 m/s) blows lightweight impurities to the side collection bag, while recycled aggregate (density 2.3-2.5 g/cm³) continues to be conveyed. After processing, the impurity content of the aggregate is reduced from 5% to below 0.5%, meeting the standards for building aggregates. It can be directly used in the production of concrete blocks, increasing the product qualification rate by 30%.

In industrial solid waste treatment, air classifiers are used for "separation of harmful lightweight impurities" and "resource recovery." For example, in electronic waste shredding, plastic shell fragments (density 0.9-1.1 g/cm³) and metal/circuit board fragments (density 2.7-8.0 g/cm³) can be separated by air classification, achieving a plastic recycling rate of 93%. This reduces harmful plastic pollution and simplifies the metal recycling process. In plastic industry waste, air classifiers can separate plastic particles from dust and pebbles (density 2.5-3.0 g/cm³), increasing plastic purity from 88% to 99%, allowing for direct granulation without washing.

2. Resource Recycling: Improving the Purity and Value of Recycled Materials

In the waste recycling industry, air classifiers are key equipment for "recycled material purification." By separating light or heavy impurities mixed in the target material, they improve the purity of the recycled material, thereby increasing its economic value. They are mainly used in waste paper recycling, plastic recycling, and waste tire processing.

In waste paper recycling, before crushing and pulping, lightweight impurities (with a lower density than waste paper) such as plastic film, tape, and rope need to be removed. Air classifiers employ a positive pressure blowing design (wind speed 6-10 m/s). When waste paper is conveyed to the airflow zone, lightweight impurities are blown to the impurity bin, while clean waste paper falls into the pulping system. The impurity removal rate reaches over 95%, preventing impurities from clogging the pulping equipment and improving pulp quality, resulting in a 5%-8% increase in the whiteness of recycled paper.

In plastic recycling, mixtures of plastics with different densities (such as polyethylene (PE) and polypropylene (PP)) can be separated using density air classification. The air separator precisely controls the airflow speed (9-11 m/s for PE and PP), utilizing the density difference between the two plastics (PE approximately 0.92 g/cm³, PP approximately 0.90 g/cm³). This causes the less dense PP to be blown to a more distant collection area, while PE settles in a closer area, achieving a separation purity of over 90%. This provides a single raw material for subsequent plastic granulation, improving the quality of recycled plastic products.

In waste tire recycling, the air separator can separate the lightweight fibers (density 0.8-0.9 g/cm³) from the mixture of rubber granules, steel wires, and fibers produced after tire crushing. By using negative pressure suction (wind speed 15-20m/s), fibers are sucked away and collected, while rubber particles (density 1.1-1.2g/cm³) and steel wire (density 7.8g/cm³) continue to be conveyed. Subsequently, the steel wire is separated by magnetic separation, ultimately yielding pure rubber particles, which can be used to make rubber floor tiles and running track materials. The fibers can be recycled as fuel, achieving "full component utilization" of waste tires.

3. Ore and Food Processing: Auxiliary Grading and Impurity Removal

Besides waste treatment and resource recycling, air separators also have important applications in ore and food processing, primarily undertaking the functions of "fine-grained ore grading" and "food impurity removal," compensating for the shortcomings of traditional screening equipment.

In ore processing, air separators are used for "separation of fine-grained ore from gangue." For fine-grained magnetite and tungsten ore with a particle size of less than 0.1 mm, traditional screening equipment is ineffective in classification. Air separators, by adjusting the airflow velocity (set to 12-18 m/s based on ore density), utilize the density difference between the ore and gangue (e.g., magnetite density 5.15 g/cm³, gangue density 2.6 g/cm³), causing heavier ore particles to fall into the concentrate bin, while lighter gangue is carried away by the airflow to the tailings bin, thus improving the concentrate grade. Data from a tungsten mine project shows that after air separation, the concentrate grade increased from 35% to 55%, and the recovery rate increased by 15%.

In food processing, air separators are used for "grain cleaning" and "impurity removal from food raw materials." Before processing grains such as wheat and corn, air separators can remove light impurities (such as dust, straw fragments, and insect-damaged grains). Through negative pressure suction (wind speed 4-6 m/s), light impurities are sucked away, while plump grains fall into subsequent cleaning processes. The impurity removal rate reaches over 98%, ensuring the grains are less prone to mold during storage and improving the purity of the finished product. In tea processing, air separators can separate tea stems and dust from tea leaves. By controlling the airflow speed (wind speed 3-5 m/s), light stems and dust are sucked away, while high-quality tea leaves are retained, improving the grade of the tea product.

Typical Features of Air Separators: 

Technical Advantages Adaptable to Multiple Scenarios The core reason why air separators are widely used in multiple fields lies in their unique technical design and performance advantages. They can solve the pain points of traditional sorting equipment when processing specific materials and meet the personalized needs of different scenarios.

1. Non-contact sorting: Avoiding material wear and contamination. Air separators separate materials through airflow, eliminating the need for direct mechanical contact. This characteristic makes them particularly advantageous when handling easily abrasive, easily contaminated, or irregularly shaped materials. For example, in waste paper recycling, traditional screening equipment's screens may scratch waste paper fibers, affecting pulp quality, while air separators prevent physical damage to waste paper. In food processing, air separators do not contact food ingredients, avoiding metal or bacterial contamination from mechanical parts, thus meeting food industry hygiene standards (such as GMP). Furthermore, non-contact sorting reduces friction between equipment and materials, lowering wear and extending the lifespan of the air separator. One food factory's air separator operated continuously for 5 years with no significant wear on core components (fan, airflow channels), and maintenance costs were only 1/3 of traditional screening equipment.

2. Flexible and Adjustable Sorting Parameters: Adaptable to Multiple Material Types The core sorting parameters of the air separator (wind speed, wind pressure, airflow direction, and material conveying speed) can be flexibly adjusted according to material characteristics, adapting to the sorting needs of materials with different densities and particle sizes. This flexibility far surpasses that of fixed-aperture screening equipment or fixed-magnetic-field separation equipment. Wind speed can be steplessly adjusted within the range of 3-20 m/s via a variable frequency fan. For different materials such as lightweight plastics (wind speed 8-12 m/s), grain impurities (wind speed 4-6 m/s), and ores (wind speed 12-18 m/s), precise separation can be achieved by adjusting the wind speed. Wind pressure can be controlled by adjusting the inlet and outlet valves of the fan to ensure stable airflow and avoid a decrease in sorting accuracy due to wind pressure fluctuations. The airflow direction can be designed horizontally, vertically, or inclined according to the production line layout to meet different space installation requirements. The material conveying speed is adjusted via a frequency converter on the conveyor belt, further improving sorting efficiency in conjunction with the airflow parameters. A resource recycling plant, by adjusting the wind speed and conveyor speed, can separate waste paper, plastics, and rubber on the same air separator, increasing equipment utilization by 60%.

3. Simple and Compact Structure: Small Footprint, Easy Installation The core structure of the air separator consists of a fan, airflow channel, material conveying system, separation chamber, and collection chamber. It lacks complex transmission mechanisms or multi-layered screens, resulting in a simple and compact overall structure. Its footprint is only 1/2 to 2/3 that of traditional screening equipment with the same processing capacity. For example, an air separator with a processing capacity of 10 tons/hour occupies approximately 5-8 square meters and can be directly installed between the conveyor belts of an existing production line without large-scale plant renovations. Furthermore, the equipment is lightweight (typically 500-2000 kg), requiring only a simple concrete foundation, and has a short installation cycle (commissioning can be completed in 1-2 days), significantly reducing the company's infrastructure and time costs. A construction waste processing plant added an air separator to its existing production line, completing installation and commissioning in just one day without affecting normal production line operation, and quickly achieving the purification of recycled aggregates.

4. High Sorting Efficiency and Large Processing Capacity: The air separator has a wide airflow coverage area, allowing materials to be quickly separated within the airflow zone. It boasts high sorting efficiency and a large processing capacity, meeting the continuous operation requirements of large-scale production lines. On one hand, the sorting efficiency (target material recovery rate) of the air separator can reach 85%-98%, far exceeding manual sorting (60%-70%). On the other hand, the processing capacity of a single air separator can reach 1-50 tons/hour, and large air separator units (multiple units in parallel) can even exceed 100 tons/hour. A large-scale municipal solid waste sorting center uses three air separators operating in parallel, processing up to 800 tons of municipal solid waste per day. The recovery rate of lightweight recyclables remains consistently above 90%, far exceeding the processing capacity of manual sorting (10 people can only sort 50 tons per day). Furthermore, the continuous operation failure rate is less than 3%, ensuring the high efficiency and stability of the production line.

5. Low operating costs and simple maintenance: The operating and maintenance costs of air separators are significantly lower than traditional sorting equipment. In terms of operating costs, the main energy consumption of air separators comes from the fan, with a power typically ranging from 5-30kW. The energy consumption per ton of material processed is only 0.5-2kWh, far lower than magnetic separators (2-5kWh/ton) and vibrating screens (1-3kWh/ton). At the same time, there is no need to consume consumable parts such as screens and magnets, further reducing operating costs. From a maintenance cost perspective, air classifiers have few moving parts (only the fan and conveyor belt are moving parts). Routine maintenance only requires periodically cleaning the airflow channels, checking the fan bearing lubrication, and tightening the conveyor belt bolts. The maintenance process is simple, requiring no professional technicians, and the monthly maintenance time is only 2-4 hours. The maintenance cost is only 1/4 to 1/2 of that of traditional screening equipment. Data from a plastic recycling plant shows that the annual operating and maintenance cost of an air classifier is approximately 12,000 yuan, while the annual cost of a vibrating screen with the same processing capacity reaches 45,000 yuan, demonstrating a significant cost advantage.

6. Good environmental performance, no secondary pollution. Air classifiers do not use chemical agents in the separation process, achieving separation only through physical airflow. This results in no secondary pollutants such as wastewater or waste residue, meeting environmental protection requirements. Meanwhile, for materials that easily generate dust (such as ores and construction waste), air separators can be equipped with sealed airflow channels and dust collection devices (such as cyclone separators and bag filters) to collect the dust generated during the sorting process. Dust emission concentrations can be controlled below 10mg/m³, meeting national air pollutant emission standards (≤30mg/m³), thus preventing dust pollution of the workshop environment and the health of operators. In food processing, the airflow channels of air separators are made of stainless steel, with a smooth and easy-to-clean surface. They can be periodically sterilized at high temperatures to prevent microbial growth, meeting food hygiene requirements and posing no food safety risks.

Air separators are primarily used for separating light and heavy components, removing impurities, and purifying resources, covering sorting needs in multiple fields. Their non-contact sorting, adjustable parameters, and compact structure solve many pain points of traditional equipment, combining high efficiency and environmental advantages. With technological iteration, air separators will be upgraded to intelligent airflow control and multi-component collaborative sorting, further adapting to complex working conditions and providing stronger support for cost reduction, efficiency improvement, and green development in various industries.

Author : Song Ying

Song Ying is a blog column writer. She has more than 8 years of experience in the manufacturing and service of environmental protection machinery. She has a deep understanding of the garbage screening and crushing industry and is happy to share practical industry knowledge and technology.