Products Description
Metal Waste Sorting Machines
I. What is Metal Waste?
metal waste sorting
Metal waste, often referred to as “scrap metal,” consists of metals or alloys that have lost their original value during production, daily life, or construction, but can be recycled and reused as raw materials.
Metal waste is primarily classified into two categories:
1. Ferrous Metal Waste: This category includes iron and steel materials, such as scrapped cars, scrap steel, machine tool scrap iron, and food cans. A key characteristic of ferrous metals is that they are magnetic.
2. Non-ferrous Metal Waste: This category encompasses all metals except for iron, manganese, chromium, and their alloys. Examples include copper, aluminum, zinc, lead, and stainless steel, which are commonly found in wires, auto parts, aluminum cans, doors and windows, and electronic products. Non-ferrous metals are usually non-magnetic and generally have a higher value compared to ferrous metals.
II. Core Principles of Metal Waste Sorting
1. Magnetics: This method utilizes permanent magnet rollers or magnetic suspension suction cups to efficiently separate materials based on their magnetic properties. Ferromagnetic materials, such as iron and steel, are distinguished from non-ferromagnetic materials. This is the most basic and cost-effective sorting technique.
2. Eddy Currents: This technology is crucial for sorting non-ferrous metals like aluminum and copper. When a conductive metal passes through a high-speed alternating magnetic field, eddy currents are generated within the metal. These currents create a magnetic field that is opposite to the original magnetic field, producing a strong repulsive force that “ejects” the metal from the material flow, facilitating its separation.
3. Sensing and Identification: By leveraging advanced sensing technologies such as near-infrared (NIR) spectroscopy, X-ray fluorescence (XRF), and laser-induced breakdown spectroscopy (LIBS), different types of metals can be accurately identified. This is achieved by analyzing their atomic spectra or optical properties, allowing for the distinction between metals like aluminum and magnesium, as well as between different grades of stainless steel, such as 304 and 316.
III. Steps Of Metal Waste Sorting
Step 1: Pre-Treatment and Feeding
Mixed waste (Municipal Solid Waste – MSW), industrial waste, or scrapped vehicle debris (Automotive Shredder Residue – ASR) is evenly fed via a chain conveyor. First, waste bags are opened using a bag-breaking machine. Then, the material passes through a drum screen for preliminary sizing, which removes fine particulate impurities such as soil and glass shards.
Key Equipment: Chain conveyor(plate feeder), bag breaker(or bag opener), trommel screen.
Step 2: Crushing and Homogenization
The material is fed into a twin-shaft shear crusher or hammer crusher, where it is crushed to a suitable sorting size, typically between 50 and 150 mm.
Key Equipment: Heavy-duty crusher.
Step 3: Magnetic Separation (Recovering Ferrous Metals)
The crushed material then passes through a permanent magnet drum or a suspended magnetic separator. Ferromagnetic steel materials are firmly attracted to the belt surface and collected as they exit the magnetic zone. This stage has the highest recovery rate, typically exceeding 95%.
Key Equipment: Permanent magnet drum, suspended magnetic separator.
Step 4: Air Separation/Bouncing Screen (Removing Lighter Materials)
Using powerful airflow generated by a blower or the specific motion of a bouncing screen, lighter materials with lower density are separated from heavier materials such as metals and glass.
Key Equipment: Air separator, bouncing screen.
Step 5: Eddy Current Separation (Recovering Non-Ferrous Metals)
The material enters an eddy current separator, where a high-speed rotating magnetic roller generates an alternating magnetic field. Highly conductive metals, such as aluminum and copper, are propelled forward by the eddy current effect and fall into a designated collection bin. Non-conductive materials, such as glass and stones, fall naturally along a parabolic trajectory due to inertia, achieving effective separation.
Key Equipment: Eddy current separator.
Step 6: Intelligent Sensor Separation (Non-Ferrous Metal Purification)
In this stage, materials are transferred through the sensor area in a single layer. X-ray fluorescence (XRF) separators can accurately determine material composition by identifying the atomic characteristics of elements. Laser-induced breakdown spectroscopy (LIBS) separators can perform more refined elemental analysis. After identification, the target material is precisely directed into the appropriate bin using a high-pressure air gun.
Key Equipment: XRF separator, LIBS separator.
IV. Post-Sorting Processing
The sorted pure metal materials will move into the downstream industrial chain to unlock their recycling value: Baling(baler machine) and Briquetting(RDF Machine), Smelting and Recycling, and Deep Processing and Manufacturing.
Guoxin Machinery Manufacturing – Professional Solid Waste Treatment Solution Partner