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Production process

At Celsa UK, we produce steel via the electric arc furnace (EAF) route; making new steel products by recycling scrap metal. The EAF process uses 100% recovered ferrous scrap metal as the primary raw material, which is melted down in the furnace using an electric current to make molten steel from which new steel products can be manufactured.

The EAF process is more flexible, produces around a sixth of the CO2 emissions, with steel manufactured this way containing about a third of the embodied energy when compared with other, more traditional steelmaking methods.

“Making new steel products by recycling scrap metal”

The melt-shop

In December 2006 Celsa UK opened its new state-of-the-art melt shop. This facility increased our crude steel production capacity from 850,000 tonnes to 1.2 million tonnes per year.

The melt shop at Celsa UK uses the electric arc furnace (EAF) process to manufacture crude steel.



Scrap arrives at our facilities by rail and by road for delivery to the melt shop. There are over 20 different grades of scrap, each representing a different level of quality. Scrap ranges from scrapped cars – which often contain impurities such as copper from copper wiring – to turnings from machining factories where the steel tends to have fewer tramp elements.


Electric Arc Furnace steelmaking

Once the correct scrap recipe is prepared, the scrap is charged into the furnace, and an electrical discharge is applied through graphite electrodes.

This produces high current electrical arcs, which melt the scrap to form molten steel. Once the scrap is all melted, there is a further refining of the molten steel, before the furnace is tapped into a refractory-lined ladle for further processing.



When steel is tapped from the EAF into the ladle, the main alloying elements are added to the molten steel.

These elements, such as manganese and silicon will combine with unwanted impurities such as oxygen and sulphur, preventing them from having a harmful effect on steel properties. Manganese and silicon are also used to produce strengthening of the steel.


Secondary steelmaking

The ladle of molten steel is moved to the ladle arc station. Here the temperature and composition of the steel are adjusted to tightly controlled limits, to ensure that the steel is of the right analysis to produce the required properties in the finished products.

Alloying elements such as manganese, vanadium or boron may be added to produce the necessary strength, ductility or toughness in the final steel.



Once the ladle of molten steel is of the required temperature and chemical composition, it is moved to the continuous caster. The molten steel is run through a gate in the base of the ladle, and into a tundish. The tundish is a bath-shaped refractory-lined vessel, which acts as a reservoir for the molten steel during the casting process. In the base of the tundish are six nozzles, from which the molten steel flows into six moulds, where the steel will start to solidify.

The rod & bar mill

Our rod and bar mill is capable of producing 890,000 tonnes each year for a wide range of reinforcing and wire rod products. In 2006 we invested £10 million in a new four-line spooler mill, making ours the first UK mill to produce hot spooled coil.

Hot spooled coil is a process vital for achieving grade 500C properties in coil format.

Rolling Reinforcing Bars

For reinforcing bar, billets are reheated to around 1150ºC in a gas-fired furnace. Reheating makes the steel softer and more deformable, so that the final shape can be produced more economically, and using less energy.

Once up to temperature the billets are pushed into the rolling stands, each of which has a pair of grooved cylindrical steel rolls. As the steel is forced through the grooves, the area of the cross section is reduced. This process is repeated continually over several stands, with the cross section reducing each time until the required dimensions are achieved. In the case of reinforcing steels, notches are cut into the grooves of the final rolling stand and the steel that fills these notches forms the ribs on the bar surface.

Rolling Reinforcing Coils

The rolling of reinforcing coil (also known as high yield coil) initially utilises the same process as with reinforcing bar. However, during the process the bar is diverted to the spooler mill after the QST process. Here, it is hot spooled by a travelling head on one of our four high speed spoolers, and forms tightly spooled high yield coils.

Rolling Wire Rod

The rolling of coil is similar to bar, except that more rolling stands are used, so that the billet can be reduced down to smaller sizes. As the cross-section is reduced, the billet is extended, so that the final length of small coil sizes can be several kilometres. In order to handle this long length, the rolled stock passes through a helical tube, spinning at high speed, which forms the rod into a helical coil. One billet is rolled into a single finished coil.

The rings of the coil are controlled cooled, using fans to blow air over the product. This cooling can also be controlled to adjust the properties of the coil products. Coil produced in this way may be ribbed, for reinforcing steel applications, or plain for subsequent drawing to wire.

The section mill

The original mill was commissioned in 1964 and updated in 1985 to produce a range of medium steel section products, including angles, flats and channels in a range of sizes and lengths up to 15.5m. Further developments came in 1993 and 1994 when the furnace was reconstructed to use either oil or gas. In 2003, after a successful commissioning period, the mill began producing equal and unequal angles, standard and UPN channels, and flat bars from 60mm to 300mm. In 2006 a new Russula process control system was installed ensuring tighter tolerances, a greater production volume, as well as extending the product range to include smaller sizes.

Our section mill is capable of producing 350,000 tonnes of merchant bar and section. It is a 14-stand cross-country mill with a billet reheating furnace that can produce 80 tonnes per hour.

Rolling sections and merchant bar products

Sections and merchant bar products, such as angles, flats and channels are rolled in a similar way to bar, but on a dedicated section mill. Grooved rolls are again used to shape the stock as it passes through the rolling line.

After rolling, the products are cooled in still air on a cooling bed, prior to in-line roller straightening, bundling, and storage for despatch.

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