Metal scrap has been salvaged and reused since the early days of metalworking. From an environmental and economic point of view, metal recycling is very effective. Metals such as steel, iron, aluminum, and copper can be recycled many times, since their metallic properties do not deteriorate with repeated smelting and casting.
The metal recycling industry specializes in extracting metal from obsolete objects so that scrap metal doesn’t end up in landfills. Instead, it is converted into raw materials for new products.
Foundries rely on metal recycling for a sustainable and cost-effective source of raw materials. According to the American Foundry Society, the price of a foundry will increase by 20-40% without the use of recycled materials.
Refinement and purification
After separation, scrap metal undergoes secondary refining. Recycling facilities sort obsolete scrap into rough categories. However, the exact chemical properties remain a mystery. To become a usable raw material, scrap needs to be purified to meet known specifications.
Scrap pieces with similar properties are fed into a large furnace and heated to a melting temperature suitable for the metal. In the process of purification, slag is formed and floats to the top of the molten metal. Slag is a rocky waste material that is separated from metal during refining. The molten metal is then tested and further refined to meet desired quality standards. Immediately before tapping and pouring, oxidized slag and dirt are removed to purify the metal. After the molten metal reaches the required characteristics, it is transferred to a cooling vessel, die ingot, or poured directly into a mold for solidification.
Manufacturing
Metal scrap is shipped worldwide for use in factories and foundries. Hundreds and millions of tons of scrap metal are consumed every year, making the transformation into a new product to start a new cycle.
Foundries get more of their raw materials from scrap storage and collection depots than from pure metal suppliers. According to AFS, ferrous metal casters use between 30-50% internal scrap, and 40-50% scrap from external sources. This includes iron materials from recycled cars, tools, and scrap steel from other manufacturing operations. These figures demonstrate a tremendous commitment to metal recycling in the metal industry.
Sustainability
Recycling scrap metal reduces the environmental impact of metal production. In 2016, the Bureau of International Recycling (BIR) reported that obsolete steel used as raw material for steelmaking reached 235 million tons—that is, 235 million tons of waste that does not go to landfill.
The process of recycling metals produces fewer emissions, and requires far less energy than producing new metal alloys. The ISRI fact sheet for iron and steel shows that recycling steel requires 56% less energy than producing steel from iron ore. In addition, by using iron scrap rather than pure materials in iron and steel production, CO2 emissions are reduced by up to 58%.
When recycled metals become available in the market, the demand for pure ore extraction decreases. Metal recycling turns waste into a useful resource, conserving energy, and reducing extraction activities and the resulting environmental impact.
