The steelmaking process is managed and developed by our teams of experts; they’re passionate about what they do and make every effort to meet customer needs and anticipate future requirements. It’s a challenging and demanding process, and we’re proud to be part of this exciting industry.
The 2,000-acre site at Scunthorpe is an integrated site – this means the raw materials for steel manufacture are transported to the site, where they are ultimately converted to steel.
The starting point – refining the raw materials
Raw materials are processed at Scunthorpe’s sinter plant, which forms an iron-rich feedstock for the blast furnaces. The ingredients – iron ore, coke and limestone fines – are carefully stacked and blended, then passed under an ignition hood at the sinter plant. This heating process is carefully controlled to make sure the resulting sinter has the right composition and optimum sizes for the next stage of the process at the blast furnaces.
In addition, coke is transferred directly to the blast furnaces where it is used as a fuel in the ironmaking process.
In Scunthorpe we have four blast furnaces named after four English queens – Mary, Bess, Anne and Victoria. Coke, iron ore, sinter and limestone are fed – or charged – into the top of the furnaces. A hot air blast of temperatures around 1,000°C is injected at the bottom of the furnace through nozzles called tuyeres. As the coke burns, temperatures higher than 2,000°C are reached and this heat creates molten metal (iron). The molten metal collects at the bottom of the furnace and the limestone combines with impurities to form slag. Because this slag is less dense than molten metal, it floats on top of the metal and can be removed – it then goes on to be used in the cement and road building industries.
The molten metal is ‘tapped’ from the bottom of the furnace into torpedoes, each one able to carry 300 tonnes of liquid iron, and moved by rail to the steel plant for conversion to steel.
At Scunthorpe, we use the Basic Oxygen Steelmaking (BOS) process – our modern convertors (or vessels) take a combined charge of scrap and liquid iron of up to 330 tonnes and convert this into steel in just 25 minutes.
When the liquid iron arrives at the BOS Plant, it’s poured from the torpedoes into refractory-lined charging ladles where unwanted elements like sulphur are removed. Scrap metal is charged into one of our steelmaking vessels (or convertors) and the liquid iron is then added to the vessel. Using a water-cooled lance, high purity oxygen is blown at twice the speed of sound onto the surface of the liquid iron at very high pressure. Lime is added to the process, which forms a slag and removes the unwanted elements from the liquid steel.
When the oxygen blowing process is complete, the steel is poured – or tapped – into ladles where the desired steel chemistry is achieved through careful addition of alloying elements and close control of the deoxidation process, ensuring a very high level of steel cleanness.
Further refinements needed by the customer can be achieved through the secondary steelmaking processes, such as our ladle arc furnace and vacuum degasser facilities, which control the steel temperatures and chemistries extremely tightly, making sure our huge range of steel grades meet the most demanding customer requirements.
Continuous casting (Concast)
Continuous casting is one of the best routes for achieving the highest levels of internal and surface quality.
Using an overhead crane, a ladle of liquid steel is transferred from the BOS Plant to the casters, where it is poured – or teemed – into the casting machine and shaped by water-cooled copper moulds of varying sizes depending on the final product to be made (range 140mm sq up to 1,970 x 305mm).
The steel is drawn vertically from the bottom of the mould through a curved arrangement of rolls and is cooled with water sprays as the steel passes through the casting machine. The resulting solidified slabs and blooms are straightened as the steel exits the bottom of the caster and are cut to the required lengths for onward processing at our mills.