As metals can be recycled repeatedly, recycling facilities that process scrap metal are particularly lucrative. Iron and steel are some of the most recycled metals, with magnets commonly used to separate these ferrous metals from mixed waste. In fact, in 2019, about 69 percent of crude steel in the United States was processed from recycled material. Recycling metals also requires less energy than mining and raw ore. To process scrap metal, recycling equipment comes in various forms, depending on the type and size of metal scrap being repurposed. Rotary airlocks play a key role in the recycling process, particularly in cases where metals are processed into a powder, where they control the flow of the powdery bulk metal.
Metal Recycling Process
The process of recycling metals depends upon what type of metal is being recycled. While iron, steel, and other ferrous metals are the easiest to recycle, non-ferrous metals like aluminum, copper, lead, tin, and zinc are commonly recycled as well. Gold, silver, titanium, platinum, and other precious metals are also recovered, primarily from items such as mobile phones or computers that have reached the end of their lifecycles.
The process involved in recycling metal normally follows these general steps:
- Collection of metal differs from methods used when recycling other materials, as metals tend to end up at scrap yards rather than landfills. Sources include junked vehicles, farm equipment, large steel structures, railroad tracks, and scrap recovered from the fabrication of new products.
- Sorting requires the separation of metals from either a stream of mixed metal scrap or multiple material waste. However, in some operations, metal recycling equipment systems involve the use of magnets and sensors. These metals are then segregated by weight, color, and cleanliness.
- Processing metals usually involves first shredding the scrap, which encourages the metal to melt. This involves much less energy than handling raw ore.
- Melting scrap metal, though it takes considerable energy, uses less than when melting raw ore. It often requires using furnaces designed to melt specific metals. Depending on the type and volume of metal and the temperature, this melting process takes a few minutes to hours.
- Purifying the metal is most often accomplished through electrolysis, when the final product needs to be free from contaminants.
- Solidifying comes next, involving the cooling of these purified metals along with conveyor belts, where they are often then formed into specific shapes and made into a variety of metal products.
- Transporting the shaped metal once cooled and solidified to factories or other places where they are transformed into new products, these metal products can be recycled again after they have reached the end of their lifecycle.
Metal Recycling Equipment
A wide variety of different implements and machinery can be used at various stages during metal recycling. Equipment like rotary airlocks performs beneficial functions well beyond their relatively small size.
Metal recycling equipment includes:
- Air separation units often utilize rotary airlocks in their design, using pressurized air to blow lighter waste material into bins while retaining recyclable metal.
- Balers push and compact metal into bales, making them easier to stack for transport.
- Claw grapplers are used in some recycling facilities to introduce scrap metal onto conveyancing systems at the beginning of the metal recycling process.
- Compactors compress scrap metal to make it easier to store and transport.
- Industrial metal shears cut up larger metal pieces, mainly sheet metal, breaking it down into thin strips to make the material easier to transport and meltdown.
- Magnetic separators remove ferrous scrap metal from nonferrous metals.
- Vibratory conveyors move scrap metal to areas where it is organized, baled, and then moved along for further processing, usually working in tandem with rotary airlock feeders during the reclamation and dust collection process.
Bulk AM Metal Powder, 3D Printing, Vibratory Conveyers & Rotary Airlocks
In many cases, more than half of the metal used in manufacturing components ends up as scrap. The value of this scrap is usually a tiny fraction of the initial purchase price for the metal. Due to transportation costs, this value lessens the further it is from a foundry. A new process is currently being developed to turn metal scrap into powdered metal that then is used to fabricate new parts using 3D printing technology.
This system envisions a closed-loop recycling system, where parts are melted down at the end of their lifecycle, turned into additive manufacturing (AM) powder, and made into new components using 3D printers. It creates a versatile feedstock for 3D printers while reducing lead time and transportation costs. This has the added benefit of increasing the value of scrap metal and reducing future waste.
Widely used for bulk powders, vibratory conveyors are ideal metal recycling equipment for conveying bulk AM powdered metals. Rotary airlocks are key parts of vibratory conveyor systems, used for reclamation and collecting dust during the recycling process. Although AM powder is most widely used as a feedstock for 3D printers, rotary airlocks can also handle bulk solids in other forms, such as pellets, crystals, and granules.
Rotary Airlocks & Dust Collection Systems
In industrial settings, dust collection systems serve an essential function, removing dust that can lead to health issues among workers. Under certain conditions, dust can even cause explosions. Dust collectors remove particulates generated from the air’s recycling process, filtering contaminants out by drawing air into filters. These then capture the dust and other particles before returning the decontaminated air back into the environment.
Dust collection systems are made up of blowers and filters and implements for storing and removing dust. Dust collectors operate most effectively when isolating these contaminants so that they are not reintroduced into the air. To do this, the receptacles that store dust during the metal recycling process must either connect seamlessly with the rest of the system or utilize airlocks.
Rotary airlocks are the most common type used in dust collection systems. They allow the bins in which dust collects to be changed without shutting the whole system down. Rotary airlocks prevent air under high pressure from leaking into lower pressure environments and keep contaminants from leaking out.