Steel's carbon dioxide emission burden

Last Updated: Mon, Jan 09, 2012 19:43 hrs

Carbon dioxide (CO2) is the principal contributor to global warming. With world steel production at 1.42 billion tonnes (bt) in 2010 and output of 116 bt till November 2011, it is natural that this industry will be counted among the major contributors of CO2 emissions. We are told that CO2 accounts for almost close to 100 per cent of greenhouse gas emissions in the process of steel making, including intermediate products like power, pellets and coke but excluding extraction of iron ore. Since 2006 when global steel output was 1.25 bt, the industry’s CO2 emission has risen from 2 bt to 2.5 bt.

For any global campaign to cut CO2 emissions on account of steelmaking in a significant way, the focus has to be principally on China, which with a production of 627 million tonnes (mt) and steel use of 600 mt in 2010 has a towering presence in the world industry. That country actually has built steelmaking capacity of 768 mt and with investments presently committed, capacity will further rise close to 800 mt. At the same time, government agencies there admit to the presence of a not insignificant presence of high cost, energy guzzling and environment polluting capacity. In fact, ahead of the Beijing Olympics in 2008, China launched a campaign to weed out ‘undesirable’ steel capacity, stuck with archaic technology. Simultaneously, it encouraged steelmakers to derive benefits of economies of scale through capacity consolidation.

China has found more success in uniting capacity than in weeding polluting mills, thanks largely to shenanigans and corruption at provincial level. Those concerned about global warming will, however, draw some comfort from Beijing’s commitment to rid the whole range of metal industries of uneconomic and fouling capacity by 2015. In the ferrous space, capacities to be guillotined in coke oven batteries, pellet units and iron and steel making plants have been identified. So also aluminium and copper smelting capacity that China should ideally do without. The average CO2 intensity of the world steel industry is 1.8 tonnes per tonne of metal cast.

No doubt after a point, the capacity of mills to cut CO2 emissions while using the conventional iron and steel making processes will be limited by the laws of thermodynamics. A major breakthrough in CO2 emissions control when hot metal is produced through the blast furnace (BF) route will call for the process to be placed on an altogether new technological pedestal. This is being attempted in the European Union under a collaborative ultra low CO2 steelmaking (ULCOS) project. The aim is to cut CO2 emission by at least 50 per cent by 2050. ULCOS is an attempt to make pig iron using raw materials in powder form, thereby avoiding ore and coke agglomeration process. The technology, if it could be made commercially viable, will lead to a major reduction in energy use with likely carbon capture and storage. Away from BF route of iron making, Posco has established the operational viability and a high degree of environmental friendliness of Finex technology, combined with mini flat mill.

As Finex allows iron making directly from iron ore fines, which account for around 80 per cent of world deposits of the mineral and non-coking coal, the process dispenses with sintering and coke plants. Posco claims that a Finex mill will hugely cut gaseous emissions and its running will need only 30 cubic metres (m3) of water a tonne of steel against 155 m3 a tonne under the BF route. Apart from the claimed environmental edge of the South Korean technology, a Finex mill will occupy 60 per cent of the land needed for identical capacity BF plant. SAIL chairman Chandra Sekhar Verma makes the point that when a steel group “goes for modernisation cum-capacity expansion as we are doing at an investment of Rs 72,000 crore, an opportunity comes your way to dispense with facilities guilty of large scale CO2 emissions, thereby making room for environment- friendly machines. SAIL is installing high capacity BFs at Bhilai, Rourkela and Burnpur replacing several small BFs will lead to considerable carbon saving as is the move to make all our steel through continuous cast route.” CO2 emissions are also sought to be checked by injecting non-coking coal dust in BFs even while the principal reductant remains coke. Thin slab casting and rolling reducing the need for reheating and therefore, cutting CO2 emissions are becoming the order with modern mills.

In a path-breaking move, the World Steel Association launched in 2008 a CO2 emissions data collection programme hoping mills across the world would respond positively by reporting their levels of emissions correlating these to operation processes. The objective is to create a data base that will lead to a good understanding of technical ways to cut CO2 emissions.

In no way, however, the initiative is to stand in the way of the industry’s capacity expansion. But in spite of the enthusiasm about the project by steel groups in the EU and the US, it may turn out to be a non-starter. For Chinese steelmakers are unwilling to part with information fearing that in the process it might be making available “useful data” to overseas competing groups.

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