- More pellet burden in BF can cut emissions by 30%
- Natural gas, hydrogen use can be raised by 10-15% in BF
- Many companies have increased PCI use in BF to 250 kg/thm
A mix of alternate fuels in blast furnace iron-making as well as a judicious mix of green DRI along with electric-arc furnace steelmaking can help India cut carbon emissions to 1-1.1 kg of CO2 per tonne of hot metal (thm) in the coming 15 years, Anil Chaudhary, Group CEO, Metals & Mining, ESSAR, and former Chairman of SAIL observed during a technology session at SteelMint’s ENGAGE2.0 webinar series held recently.
However, metallurgical coke usage can only be reduced, he said, as replacing coke in steelmaking is still a distant dream. In fact, in the near past and in the short term, 38 mnt of BF-BOF steelmaking capacity has been added to India’s BF ironmaking infrastructure, which is likely to sustain till 2065, mainly due to the lack of a viable alternative that promises economy of scale.
As a matter of fact, coal-based DRI production in India is much more polluting than BF-BOF, he stated.
Going forward, India’s reliance on met coal is slated to increase, given the exponential growth in steel demand, although imports of met coal and PCI at current rates are uneconomical.
The National Steel Policy projects steelmaking capacity to rise to 300 mnt by 2030 and 60% of that production will be through the BF route Nevertheless compelling reasons why we should cut down met coal consumption are domestic scarcity, high-priced imports and emissions concerns, he observed.
Raw material mix
New BFs should focus more on using pellet as feed rather than sinter and lump and if pellet burden is increased in BF, emissions can be at least reduced by 30%.
“Although the general line of thought is that small BFs lag behind when it comes to productivity, my experience is that with the increase in the pellet burden, the smaller BFs have been more successful in increasing productivity by at least 30%,” Chaudhary said.
“With ideal pellet and sinter feed, we would be able to bring down emissions by at least 30%,” he stated.
Change in operating practices
Change in operating practices is required to bring down emissions. Distribution of burden, tapping practices, etc. which always results in minimisation of the fuel rate ought to be encouraged. By fuel is meant how much met coke, pulverised coal injection (PCI) coal and nut coke is used in the BF.
Good operating practices mean that from the general 530 kg of coke per tonne of hot metal, steelmakers should be in a position to bring down the coke rate by 20-30 kg per tonne of hot metal.
Other practices such as recirculation of BF top gas are essential, although these technologies are still under development.
In the country today the new BFs that are coming up are using the top recovery turbine (TRT) to generate power. A BF of, say, 4,050 m3 can generate power of up to 15 MW. TRT equipment is available for around INR 25-30 crore. So, with a small operational cost the quantum of emissions reduced by not using coal in the thermal power plant is considerable. This is a classic example of indirect reduction of coal usage in an integrated steel plant.
For coke-making the top charge batteries are prevalent due to which consumption of coke in the BF is higher. These can be replaced with stamp charge batteries, which will reduce operational costs as well as consumption of coke in BF.
Alternative fuels
The alternative fuels that can be used in the BF to bring down the fuel rate are natural gas, which can be used to the extent of 10-15% as well as coal bed methane (CBM) and coke oven gas (COG)/syngas. Hydrogen is still a distant reality.
The choice of fuels is driven solely by economic considerations.
In BFs, hydrogen can be used to the extent of 12-15%. SMS has developed a technology which can help maximise the injection of syngas and hydrogen. To make one tonne of iron we would need 150 kg of hydrogen and today the price of green hydrogen is INR 450 per kg. If we get hydrogen at economical costs, say $1 per kg as is being envisaged, emissions can definitely be reduced.
Many companies have increased PCI coal injection in the BF by as much as 250 kg per tonne of hot metal. Of course, there is no limit and this is mainly a cost-cutting measure. We know that one tonne of PCI replaces one tonne of coke. For making one tonne of coke you would need 1.5 t of coal, the expert stated.
Green steel demand
Green steel demand will slowly get generated in India as carbon credits come into place like in Europe. Companies will seek to implement latest technologies in order to stay at an advantageous position in the carbon curve.
As Europe is taking a lead position in this respect, with measures such as Carbon Border Adjustment Mechanism (CBAM), it is expected that leading Indian steel firms will take the decarbonisation lead in order to maintain their strong presence in the export market.
Leave a Reply