Making steel

A behind the scenes visit to one of the biggest steelworks in Britain reveals how this essential metal is made

Steel is everywhere. Found in bridges, trains, computers and even your cutlery drawer, this alloy is one among the foremost widely used materials within the world. it's stuffed with properties that make it the go-to choice for the development of a number of the world's most incredible structures, while being adaptable enough to be used for car doors and teaspoons, but how is that this amazing construction product constructed itself? To answer this we visited the CELSA Steelworks in Cardiff, Wales, to induce to grips with the method of making steel.

Essentially, there are two main methods of constructing steel today. One is named basic oxygen steelmaking (BOS), which is how 60 per cent of the world's steel is currently produced. to start this involves extracting ore from rocks within the ground. Next comes a process called smelting. Steelworkers fill a furnace with the ore, charcoal and limestone, pump vast amounts of air into the bottom-fuelling the fireplace that was created when an electrical charge was put through the system; this melts the iron down, allowing workers to 'tap' it out of the furnace. Pumping oxygen through the liquid iron oxidises the carbon content and, whenit reduces to a specific level, steel is born.

The second process is termed arc furnace (EAF), which rather than raw materials uses scrap steel to make new metal. it's this latter process which is used at Cardiff's CELSA steelworks, all oversean by Ron Davidge, who has worked for several years within the steelmaking industry-first within the melt shop then the room.

"The EAF process starts within the scrapyard," Davidge tells us. "We put the rubbish into the screening process which separates the nice steel from the rubbish. It's then loaded into the hampers and brought into the melt shop. we've got different metal ratios supported the grade of steel we're making. the simplest steel contains a copper content of around 20 per cent. way more and therefore the steel is wekened, as copper wire contains a habit of breaking apart stressed."

The melt shop is that the vast open building within which the really exciting a part of steelmaking occurs-home to the furnace fire.

With a wrenching and a scraping, the lid is lifted off the furnace and also the huge basket stuffed with pieces of trash is tipped into the furnace. Lifted up with the lid are three immense graphite electrodes, which are glowing red-hot.

"We need to keep the furnace at an incredibly hot temperature", explains Davidge, "because if we let it settle down it takes an enormous amount of energy and time to reheat and that we don't need to waste either of these. After we basketball shot the metal, the electrodes get lowered and that we put an electrical charge through them that's conducted by the scrap. The electrodes have an angled base to extend their expanse."

When it's time for the second bucket of scrap to be lowered into the furnace, which we're told is currently running at around 1,650 degrees Celcius (3,000 degrees Fahrenheit), the lid is raised and an improbable ball of flame billows out of the container. The scrap is released into Inferno where it's rapidly melted down into the liquid steel bath.

"The walls of the furnace are lined with silica brick, which includes a very high melting rate. Even so, the period of even good-quality brick only lasts about three weeks before it has to be changed. we've to create sure we protect our furnace because they're expensive", says Davidge. "The furnace is additionally lined with manganese and slag form previous meltings to supply some extra protection."
It is at this time within the process that the BOS and EAF steelmaking methods converge and follow the identical path.

Once the bulk of the steel has been melted down, a burst of oxygen is distributed through the steel oxidising are removed and therefore the perfect level of carbon content is reached.

Slag is that the thick substance created from all the waste products within the process. so as to get rid of this, the furnace is tipped back and forth some times, allowing the waste to be pushed out of the slag door. This process will often lose a touch of liquid steel but it's a suitable sacrifice at this stage. After the maximum amount slag as possible is far from the furnace, the tapping process can begin.

There are two pipes below the furnace, one in every of which allows a stream of 145 loads of molten steel to run down it into a shower, while the opposite contains metals and alloys, such assilicon and manganese, which is able to be poured into the molten metal mixture to form the proper grade of steel for that individual batch.

The bath is analysed and more tweaks are made to the constitution of the steel before it's left to chill slightly, developing a dark, bubbling surface skin, looking a small amount sort of a slightly over-grilled cheese sandwich.

The next stage is to show that molten steel into steel bars and rods. this is often done by craning the container up onto a large rotor arm, which holds one full bath in waiting and another over a trough. This trough has six exit points, through which the molten metal flows. so as to stay it flowing evently, the trough vibrates slightly, which keeps the liquid metal constantly moving. The exit points are copper pipes, which drop at a small angle before levelling resolute a horizontal half-pipe, very similar to a kamikaze water slide.

"As well because the vibrating pipes, the angled drop is meant to stay the stream consistent and smooth," Davidge says. "Too sharp a drop and cracks could appear, too shallow a drop and also the metal are too cool for it to be cut."

The constant flow pushes the molten metal along the road, where it cools surprisingly rapidly. Mechanical cutters are founded, again at a small angle so it can cut the metal in an exceedingly line because it continues to maneuver during a process called continuous casting. The swiftly cooling billets turn from red to grey ahead of our eyes, before being stacked on the rear of a large lorry to be transported to the road and bar mill where they're going to be shaped.

The whole process takes around 45 minutes from the instant the primary basket of steel is deposited within the furnace to the purpose at which the container has finished emptying its load of molten steel into the trough.

Any delay would cause the whole process becoming much less efficient, whether it is the furnace being underused, the molten metal cooling an excessive amount of and needing reheating or the billet stream grinding to a halt. The plant trends to figure 24 hours day, seven days per week, with maintenance being worn out brief periods of downtime or scheduled shutdowns.

We continue outside to require a fast shop around the 'slag shed', where all the waste product is deposited. However, this can not get thrown away because the slag are often sold on to companies as a road-building product.

Inside a steelworks is hot, noisy and dusty (they create 50 loads of dust every day) and also the pressure to induce things right is immense in concert slip-up can compromise a whole day's work. Steel is pretty big bussiness and to experience the raw power of that furnace and therefore the dedication of the workers to confirm many plenty of top-quality steel gets produced a day was incredible.
Steel, in its many forms, may be a vital material in today's society and its strenght, durability and adaptability is merely mirrored by the people and also the process that makes it.