If you are new to the world of scrap metal collecting, it can take a while to learn about the various factors which affect the value of your haul. This week, we address the most common cause of metal deterioration, rust.
What is Rust?
Also known as iron oxide, rust is formed as a result of what is known as the redox reaction between oxygen and iron when exposed to moisture and air. Over time, any iron containing metal will corrode and disintegrate.
When oxygen combines with metal at the atomic level, oxide is formed and this weakens the bonds of the metal. Although to the human eye, exposed metal appears solid, it is actually covered in tiny pits and cracks, which water molecules can penetrate.
What kinds of materials are affected by rust?
The red oxide that we typically think of as rust affects iron and iron alloys such as steel. Many other metals can be affected by corrosion, but the oxides they produce are not recognised as rust.
Does it devalue metal?
Because rust compromises the chemical structure of metal, it affects its recyclability and therefore its value. Whilst superficial rust stains are unlikely to take much value away from the metal and can be buffed off before processing, friable (crumbling) rust tends to indicate that the rust has penetrated beyond the surface, and seriously compromised the metal structure. When friable rust is present, most metal becomes worthless.
Are there any hazards associated with rust?
Corrosion degrades metal on a molecular level, and compromises the structural integrity of buildings, bridges, and other civil structures. Rust not only weakens metal, as it has a much higher volume than iron, it tends to build up and shift adjacent parts via a process known as rust packing.
The rough surface which rust creates is also prime habitat for a bacterium known as Clostridium tetani which causes tetanus. For this reason, it’s crucial that scrap metal collectors wear protective clothing when collecting rusted scrap.
Can it be removed?
If the rust is superficial, there are dozens of different methods you can use to remove it. However, once the rust penetrates deeper into the metal, it can only be removed by physically cutting or beating away the damaged area.
Metal Men specialise in metal recycling in Melbourne. To learn more about our prices, or to order a pickup, please don’t hesitate to get in touch with us by calling 03 5941 6677.