Steel can be produced from raw materials using two main methods: using a blast furnace or using an electric arc furnace.
Steel Production Using a Blast Furnace
The blast furnace is the first appliance that is usually used when extracting steel from iron oxides. The first blast furnaces in recorded history can be traced back to the 14th century. These furnaces had the capability of producing 1 ton of iron daily. Though the design and production capability of blast furnaces has improved greatly over the years, the working principle still remains the same; for a blast furnace to produce pig iron, you need a combination of ingredients that includes limestone, coke and iron one.
The coke used in blast furnaces is usually sourced from coal. Coal is usually crushed and ground into a fine powder before being heated in an oven to approximately 1800 degrees Fahrenheit. The heating must be done in the absence of oxygen. As the heat in the oven increases, the coal usually melts and in the process highly volatile compounds such as tar, oil, nitrogen, sulphur and hydrogen are removed. The remaining cooked coal (coke) is then given a reaction time of between 18 to 24 hours before being removed from the oven. The coke from the oven is then usually cut into pieces that range from 1 to 4 inches. The result is usually a hard, porous black rock that has high carbon concentrations (90%–93%) as well as some traces of sulphur and ash. The coke which has high concentrations of carbon usually provides the strong heat, gases and permeability which are required to melt iron one, pellets and sinter.
Production of Steel Using Electric Arc Furnaces (EAFs)
The first EAFs can be traced back to the late 19th century. Today, most of the steel production is done using EAFs, with these appliances producing ⅔ of the steel in the US. The main difference in the working principle of EAFs and blast furnaces is that these appliances rely on electrical current to melt down reduced iron or scrap steel into molten steel.
After production, stainless steel can be put to use in various industries including:
- Architecture and Construction Industry
The use of stainless steel in the construction industry gained prominence during the art-deco period. One of the most famous buildings of the time – The Chrysler Building – had an upper part that was made of this material.
Today, this material is widely used in the construction industry because of its strength, flexibility and ability to resist corrosion. In building exteriors, it is mostly used as cladding for high impact buildings while it can be put to multiple uses in building interiors such as in making handrails, countertops and blacksplashes. It can be used for scaffolding but mobile aluminium scaffold is becoming more and more popular.
It is fairly easy to weld stainless steel and once polished, it usually has an attractive finish that does not require a lot of maintenance. This material has been widely used in today’s architectural scene as can be observed in the One World Trade Centre in New York, the Helix Bridge in Singapore and the Eurostar Terminal in Waterloo Station, London.
The heavy use of steel in the construction industry can also be attributted to the fact it allows for the construction of green buildings. This material is used in sustainable building projects because 90% of stainless steel is usually sourced from recycled metal and further, when the material is polished, it can reflect light into a room allowing for more energy savings.
- Automotive and Transportation Industry
This material was first used in the car manufacturing industry by the Ford Motor Company in the 1930s during the production of concept cars.
Today, this material is primarily used in the automotive industry for the production of trim and grills as well as exhaust systems. However, because of new laws governing car emissions as well concerns on the impact of other materials on the environment, many car manufacturers are turning to stainless steel to produce other structural components for vehicles.
In the transportation sector, steel is used in shipping containers, refuse vehicles, tankers and in many other areas. It is favoured for building transportation containers since its high density allows for the construction of thinner fuel containers which help increase energy savings. Since it is corrosion-resistant, it also does not require a lot of cleaning and maintenance.
- Medical Industry
Stainless steel is used in medical settings because it can be easily sterilised and it is resistant to corrosion. In this industry, it is used to manufacture kidney dishes, operating tables, surgical equipment, dental equipment and medical equipment such as MRI machines.
This material also happens to be widely used in surgery. For example, it is used to make replacement joints, steel pins and the plates used to hold broken bones into place as one heals.