How is Metal Recycled?
Metal recycling involves collecting and sorting scrap metal, melting it down, and then using it to create new metal products. The process helps to conserve natural resources, save energy, and reduce greenhouse gas emissions.
1. Collecting Scrap Metal
The first step in collecting scrap metal is to designate specific bins at your home or business to hold the metal safely. If you have a lot of scrap metal, some recycling facilities may be able to help arrange transportation.
Once the recycling facility has received the scrap metal, the sorting process begins. Metals are separated from other materials and then sorted into ferrous and non-ferrous metals using magnets. The metals are then further sorted by type and cleanliness.
In this stage, the metals are initially compressed and squeezed to reduce their size. Later, hydraulic machinery is employed to cut them into smaller pieces.
The hydraulic machinery is capable of generating sufficient pressure to slice large metal pieces. It achieves this by utilizing a fluid that circulates throughout the machine and the motors, thereby pressurizing it.
Following that, the scrap metal is passed through hammer mills to shred it into smaller pieces. Shredding the metal has the advantage of increasing the surface area-to-volume ratio, which makes the melting process easier.
The metal is then melted in a furnace set to a specific temperature based on the metal being melted. The size of the metal and furnace affects the melting time. The amount of energy used in this process is far less than what’s required to mine new metals.
6. Purifying of Metal
To ensure quality, metals are purified of any contaminants. This can be done through electrolysis, distillation, and liquation.
Electrorefining is the term used to describe the process of purifying metals through electrolysis. During this process, the impure metal is utilized as the anode, while the refined metal is deposited onto the cathode in an electrolytic cell.
Distillation is a purification method that utilizes zinc and mercury for metals with low boiling points. The process involves heating the impure metal above its boiling point to generate vapors, leaving the impurities behind. As the impurities do not vaporize, they can be separated from the purified metal.
Lastly, the process of separating metals from an ore or alloy is called liquation. The material is subjected to heat until one of the metals begins to melt and separate from the others, and can then be collected.
7. Cooling and Solidifying the Metal
Chemicals may be added to melted metals to create desired properties. The melted metals are then solidified through a cooling process and may be melted into sheets or compacted into blocks for easier production.
8. Transporting the Metal Bars
Once solidified, the metal is packaged and transported to manufacturing facilities where it will be used to create new products.