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Irons in the fire

Sanghoon Joo

Sanghoon Joo, Myoungkyun Shin, Martin Schmidt, inventors of a new way to manufacture steel

Mankind has been honing the art of steel production for thousands of years. But as natural resources dwindle and environmental regulations tighten, a group of scientists are redefining steel production with a next-generation alternative to the centuries-old, traditional blast furnace.

A global hunger for steel

Today, it seems almost everything we use is either made from or manufactured with steel. It can be found nearly everywhere from automobiles to mobile phones, televisions to telescopes. The metal's unique versatility, combined with rapid growth in highly populated Asian countries, is the reason why global steel production nearly topped 1.5 billion metric tonnes in 2011. The World Steel Association estimates that continued high demand will further boost this number an additional 25% by 2015.

But more steel means more pollutants in the air, and the iron and steel sector already accounts for 27% of total industrial CO2 emissions and 5% of all man-made greenhouse gases.

This makes steel manufacturers a prime target for lobbyists pushing for cleaner industrial practices. One of the ways steel manufacturers are scrambling to meet tougher environmental checks is by phasing out the traditional blast furnace, which originated in the 1500s and has been widely regarded as the most effective way to generate steel for more than a century.

What one is left with is the same high-quality steel for three quarters of the price.

Streamlining the smelting process

Sanghoon Joo

The sheer amount of steel produced every year - not to mention its countless applications and end products - means that even the slightest change in production can have significant impact.

With that in mind, Korean steelmaker POSCO teamed up with Siemens VAI of Austria, tasking their best inventors with conceiving a way to streamline the smelting process. They developed a new method called FINEX, a nod to the granular form of fine iron ore that is used to produce molten iron in a single step on its way to becoming steel.

While conventional blast furnaces rely on processes known as coking and sintering to purify coal enough for smelting iron ore, the new method completely eliminates the need for expensive coke and completely avoids coke-production processes.

FINEX also forgoes use of the expensive, sticky coal that comprises only 15% of global coal reserves, instead opting for the more plentiful, low-grade coal that makes up the other 85% percent. What they are left with is the same high-quality steel for three quarters of the price.

FINEX is a winner both on the commercial and on the environmental front.

A more sustainable steel

FINEX is a winner both on the commercial and on the environmental front. A 25% reduction in operational costs means a windfall in profits. And not only are finite natural resources spared, but due to metallurgical reactions taking place in a closed atmosphere, the inventors have also almost eliminated emissions of sulphur, nitrogen oxide and dust - pollutants that contribute to climate change.

Actually, some 99% of these gaseous byproducts are captured by FINEX and used for electric power generation, ensuring nothing goes to waste. The result is a new production technique that requires 2.5 fewer gigajoules (GJ) of energy than the traditional blast furnace method to produce a single tonne of steel.

That means the Pohang steelworks in South Korea, with an annual production capacity of 1.5 million tonnes, requires approximately 3.75 million fewer GJ annually than if it were using the traditional blast furnace method. It also emits about 12% less, or nearly 350,000 fewer tonnes, of CO2 into the air every year.

That's something, especially when considered that the steel mill has produced enough steel for some 250 million cars since their erection in the 1970s.

Steeling for the future

With preliminary processing of raw materials eliminated, outfitting plants with FINEX costs 8% less than blast-furnace facilities of the same scale. POSCO installed its first experimental plant with the new system in South Korea in May 2003. Four years later investments into researching and developing FINEX were already approaching $600 million.

By 2009, a second commercial-scale plant was operational in India with an annual capacity of 1,500,000 tonnes and construction of another plant in South Korea, worth some $1.2 billion, began in late 2011. It is expected to be operational by July 2013.

Various steel producers around the world have developed competing technologies to replace their aging blast furnaces, but only one other company - Australia's HISMELT plant with a production capacity of 800,000 tonnes per year - has successfully commercialised its next-generation technology to the point where it could scrap its blast furnaces altogether.

POSCO anticipates that, by the end of 2013, its annual production capacity with FINEX technologies will be 4.1 million tonnes - one fourth of what it produces in a year.

The fact that POSCO can finally stop importing its core technologies from other advanced neighbouring steel producers is enough to lead the company to believe that its new technology will give it a competitive edge for decades to come.

POSCO anticipates that, by the end of 2013, its annual production capacity with FINEX technologies will be 4.1 million tonnes – one fourth of what it produces in a year.

How it works

Iron only occurs as iron oxides in the Earth's crust, and these ores must be reduced to extract the metallic iron from the rock. In this method, fine iron ore passes through a series of fluidised bed reactors in a furnace, where it is heated and reduced by chemical reactions that are catalysed by a special reduction gas flowing in the opposite direction.

After exiting the final reactor, the molten iron is transferred to a so-called melter gasifier, where smelting takes place. Pulverised non-coking coal is added to the dome of the melter gasifier, where it is turned into gas and injected together with oxygen into the vessel below to expedite the smelting process.

Some of the gas, however, is rerouted back up through the fluidised bed reactors to take on the role of the aforementioned reduction gas. The whole process reduces hot metal production costs by approximately 15% per tonne because it relies on low-grade, low-cost materials rather than expensive coking coal.

No steel? No skyscrapers

In 19th-century Chicago, urban buildings were still made of wood. When the Great Chicago Fire tore through the city in 1871, these vulnerable structures didn't stand a chance. So as architects and construction workers began to quite literally rebuild a large swath of the city from the ground up, they turned to less flammable materials to create new high-rises.

Stone proved less than optimal because stone walls needed to be much thicker to prevent the building from collapsing under its own weight.

It wasn't 1885 that engineer William Jenny realised that building frames made of iron, and eventually steel, offered the same stability as stone without the suffocating thickness.

Today the housing and construction sector accounts for 50% of global steel consumption. In 2011, the amount of steel produced reached 1,527 megatonnes (Mt) - up from 28.3 Mt in 1990. Around the world, the steel industry directly employs more than 2 million people.