Ferrous metals are pure iron or an alloy that contains iron. The word ‘ferrous’ was derived from the Latin word ‘ferrum’ meaning iron. The most common ferrous metal alloy is steel. Ferrous metals have small amounts of other metals or elements added, to give the required properties. These metals are magnetic and provide very little resistance to corrosion.
All commercial forms of iron and steel contain carbon, which has become an integral part of the metallurgy of iron and steel. The demand for ferrous metals is strong, thus scrap metals are also highly sought after. Most recycling companies pay for scrap metals.
Types and Features of Ferrous Metals
There are many variations of ferrous metals available in the market today. Some of the key types and their features are listed below:
- Cast iron - Hard, brittle, strong, cheap, self-lubricating.
- Mild steel - Tough, high tensile strength, ductile. Because of low carbon content it can not be hardened and tempered. It must be case hardened.
- High carbon steel - The hardest of the carbon steels. Less ductile, tough and malleable.
- Stainless steel - Corrosion resistant
Other available types are construction steel, free cutting steel, high strain steel high temperature steel, low temperature steel, and spring steel
Manufacturing process of Ferrous Metals
Ferrous metals have to be extracted from iron ore. The source for iron ore is the earth's crust, which contains metals and metal compounds such as iron oxide. However, the ore is often mixed with other substances. In order to optimize the usage of the metal, it has to be extracted from the mixture.
The method primarily used to extract metals from the ore depends on their reactivity. In the case of iron, a less-reactive metal, it can be extracted by reduction with carbon or carbon monoxide. Iron is then extracted from iron ore in a huge container called a blast furnace. Oxygen must be removed from the iron oxide to leave the iron behind.
Applications of Virgin Material Ferrous Metals
Ferrous metals are used in numerous applications. The following are key uses:
- Girders, plates, nuts and bolts
- Heavy crushing machinery
- Car cylinder blocks, machine tool parts, vices, brake drums, machine handle and gear wheels, and plumbing fitments
- Gears, shafts, engine parts
- Cutting tools for lathes
- Kitchen draining boards, pipes, cutlery, aircraft
- Chisels, files, lathe tools, hammers, drills, taps and dies
- Metal ropes, springs, wire, garden tools
Environmental Impacts of Ferrous Metals
Scrap ferrous metals such as car bodies and old farm machinery contain many toxic chemicals including oil, petrol and diesel, battery acids, transmission and brake fluids plus radiator coolant that can leach into the environment when dumped in landfills or other illegal places.
These scrap metals also create safety and fire hazards. The sharp jagged edges of the rusting metal might injure people and wildlife, while the chemicals could cause bush fires.
Illegally dumped scrap metal is expensive to clear by the local government. These costs will include collection and disposal of material, increased enforcement and surveillance, prosecution, education and awareness programs.
Recycling Process
The use of scrap ferrous metal has become a core part of most steelmaking companies today as it helps improves the company’s economic viability and whilst decreasing environmental impact. Another reason is that in comparison to ore extraction, using scrap ferrous metals reduces energy consumption, CO2 emissions, water consumption, and air pollution.
Recycling of ferrous metals helps to reduce the quantities of solid waste deposited in landfills, which have become more expensive. As these metals are magnetic, scrap can be collected using a magnet and sent to a recycling unit.
Ferrous metal-based scrap products can be recycled by remelting, recasting, and redrawing processes completely within a steel mill. These processes are far cheaper than producing new metal from the basic ore. Manufacturers produce their own coke. The by-products from the coke oven include several organic compounds, ammonia, and hydrogen sulfide. All these can be sold to various consumers.
One of the largest sources of scrap steel is reprocessing old automobile bodies. The automobile body is crushed and flattened, and then is shredded into small pieces by hammer mills. Ferrous metals are separated from the shredder residue using powerful magnets while other materials are sorted manually or by using high-pressure air flows and liquid floating systems.
Applications of Recycled Ferrous Metals
Studies have shown that recycled steel has the same strength as new steel. Today most appliances contain about 75% recycled steel.
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