India: High-quality DRI can help maximise induction furnace productivity, improve efficiency

India's crude steel production is around 125 million tonnes (mnt)/year. Out of this, 45% is produced through blast-furnace-basic oxygen furnace (BF-BOF) route and the remaining through the electric-arc furnace/induction furnace (EAF-IF) route.

Sponge iron, also known as direct-reduced iron (DRI), is used as a substitute for scrap in steelmaking in induction and electrical arc furnaces. Over the years, shortage of melting scrap has made DRI a significant raw material for manufacturing high quality steel in India. The share of DRI in India's total crude steel production is about 30%.

"To maximise the productivity of the induction furnace, it is important to feed a high-quality raw material. In case of DRI, the material specification should be FeM 80% or higher. This will not only help in increasing productivity of the furnace but will also improve its efficiency," said Vivek Agrawal, Chief Operating Officer, Godawari Power and Ispat Ltd. (GPIL)

He was speaking on the topic 'Optimising Performance: Maximising Productivity with DRI in Induction Furnaces' in a session as part of SteelMint's Engage 4.0 webinar series.

"High-quality DRI not only consumes less energy to melt and saves production costs but also increases the yield with less generation of waste products i.e., slag," he observed.

GPIL uses around 95% of DRI and 5% scrap and Fem in DRI is 84-85% while gangue (Al2O3+SIO2) is around 4-5%. Yield by using 95% DRI having 84.5% Fem is around 86.5-87.0%, informed Agrawal.

Indian DRI industry

India is the world's largest DRI producer with an annual installed capacity of around 62 mnt. Odisha is the major DRI-producing state which contributes nearly 24% of India's DRI.

India's DRI production increased by 12% y-o-y to 43.1 mnt in FY'23, with Odisha, Chhattisgarh and West Bengal being the largest producing states.

India also exports DRI, majorly to Nepal, Bangladesh and Bhutan. The country exported 1.13 mnt in FY'23.

Efficiency and productivity in IF steelmaking

Cost optimisation: Efficient operations lead to reduced energy consumption and lower operating costs. By maximising productivity, manufacturers can produce more with the same resources, leading to improved cost-effectiveness and profitability.

Quick turnaround times: Efficient operations in induction furnaces ensure rapid melting, casting, and refining processes, enabling manufacturers to respond swiftly to market requirements.

Quality control: Efficient operations help maintain consistent and high-quality output. Precise temperature control and accurate alloying processes in induction furnaces contribute to the production of steel with desired properties and minimal defects.

Resource utilisation: Efficient operations optimise the use of raw materials and minimise waste generation. By maximising productivity, manufacturers can make the most of their resources and reduce the environmental impact associated with excessive material consumption and waste disposal.

Best practices for DRI utilisation in IFs

Charging strategies

• Ensuring efficient and controlled charging of DRI into the induction furnace.
• Optimising the batch size of DRI charged into the furnace can help achieve maximum productivity.
• Longer holding times require more energy consumption, which can reduce the lifespan of the induction furnace. Manufacturers should consider short holding times instead to improve the melting equipment's efficiency by using high-grade DRI with 95% charging ratio.
• Usage of normal ramming mass instead of silica ramming mass increases the heat cycle timing which, in turn, increases productivity.

Process optimisation

• Maintaining precise temperature control throughout the melting process is essential to maximising productivity. Advanced temperature monitoring systems and control algorithms can help maintain optimal operating conditions.
• Optimising the power and frequency settings of the induction furnace based on the DRI charge characteristics can significantly impact productivity. This requires careful experimentation and monitoring to find the optimal power and frequency levels.
• Implementing process automation, including advanced control systems and data analytics, can help optimise furnace operation and enhance productivity.
• Maintenance of the induction furnace is necessary to keep a check on the small problems to not let them become big disasters.

Outlook

Agrawal said he was very positive about the growth of the DRI industry in India. The country will need more DRI to meet the government's target of 500 mnt of crude steel production by 2047.

However, as the decarbonisation wave sweeps through the steel industry, India's predominantly coal-based DRI sector will have to necessarily pass through a phase of energy transition. It is expected that the transition pathway will be from coal to natural gas and renewable energy and, ultimately, green hydrogen.