Global demand for steel is growing. There is a huge backlog of infrastructure projects, especially in developing countries. At the same time, steel production is responsible for almost 10% of global CO2 emissions. The EU has recognized this problem and set a target in the Green Deal to reduce emissions in all sectors to become carbon neutral by 2050. This will also require adjustments in the steel industry: green steel is the goal.
What is green steel?
Green steel refers to a production route that produces significantly less CO2 than conventional steel production. Currently, the production of one tonne of steel releases around ten tonnes of CO2. The aim of green steel production is to reduce emissions to just one tonne of CO2 per tonne of steel. Completely CO2-free steel production is not yet possible. Nevertheless, the life-cycle assessment (LCA) of the steel industry can be significantly improved through targeted measures.
What measures are being taken to reduce CO2?
Several approaches are being taken to reduce CO2 emissions from steel production. One important measure is to recycle steel scrap to reduce the need for iron ore. This not only conserves resources but also significantly reduces energy consumption. A second important step is the increased use of Electric Arc Furnaces (EAFs), which are a more environmentally friendly alternative to traditional Blast Furnace route (BF). The use of renewable energies such as wind, solar and hydro power also plays a key role.
Scrap recycling
A very large proportion of all types of steel scraps can be re-melted and recycled into new steel. This offers huge potential in moving towards a circular economy by conserving resources and reducing emissions. However, the quality of steel scrap can vary and is often inferior to steel made directly from iron ore. In addition, the volume of recyclable steel scrap will not be sufficient to meet the ever-increasing demand for steel. It will therefore be necessary to continue using iron ore as a raw material in the future.
Use of electric arc furnaces (EAFs)
Electric arc furnaces (EAFs) have been used in steel production for decades but have played a minor role until now. In the future, they will play a major role, gradually replacing the traditional Blast Furnace production route. To make this change possible, however, EAFs need to become larger and more powerful, which poses a number of technical challenges. The aim is to increase the efficiency of Electric Arc Furnaces so that they can compete with the production capacity of conventional Blast Furnaces. This requires innovation in furnace technology to achieve higher temperatures and faster processes. In addition, the integration of renewable energies into the operation of EAFs is a key step towards further reducing the need for coal and thus CO2 emissions. Another aspect is the quality of the steel produced: while EAFs are excellent for recycling scrap, it is important to ensure that the steel produced meets the same quality standards as steel from traditional Blast Furnaces.
Challenges and solutions for EAFs
Larger EAFs and changes in the composition of raw materials present new challenges to the steel industry. The consequences of higher furnace weights, fluctuating charge levels and sometimes poorer raw material quality need to be managed.
- Increased furnace weight
- Fluctuating liquid levels
- Poor product quality
- Improved technology: precise EAF scales and condition monitoring
- Use of more environmentally friendly raw materials based on iron ore
To maximize the efficiency of EAFs, it is important to use them to their full capacity. Overfilling furnaces can lead to material fatigue and damage, which shortens the life of the equipment and results in costly repairs. With larger furnaces, it is more difficult to accurately measure the material being processed, increasing the risk of over- or underfilling. Accurate measurement and control mechanisms are therefore essential to ensure optimum furnace utilization and minimize material fatigue.
EAFs require a liquid crude steel sump to operate so that no material breaks through during charging and the melting process remains stable. However, the sump must not become too large or valuable usable volume in the furnace will be lost. Careful control and monitoring of sump levels is therefore essential to ensure optimum utilization of the furnace and maximize the efficiency of the new green steel production.
Compared to steel made directly from iron ore, electronic scrap has a lower metallic purity. In addition, the metallic purity varies considerably as the scrap comes from different sources and may contain different impurities. The fluctuating quality of the raw material can have a negative impact on the qualities of the final product, emphazising the need for strict controls and refining processes in production. Ensuring consistent product quality remains a key challenge when using EAFs to meet market and industry requirements.
Modern EAFs are fully supported by load cells that allow continuous monitoring of the furnace weight. These precise furnace scales are essential for controlling and optimizing the production process. By continuously determining the furnace weight, the furnace usable volume can be optimised and overflow can be avoided, increasing both the safety and efficiency of production. Accurate weight control also enables efficient energy use, as adjustments can be made in real time. After each casting period, which lasts four weeks, up-to-date data on the weighing status of the furnace is made available. This information is vital for maintenance and planning of future production cycles. As furnace size and throughput increase, this condition monitoring becomes more demanding and important. Accurate monitoring and analysis of furnace condition is therefore essential to ensure the long-term performance and reliability of the systems.
The use of Direct Reduced Iron (DRI) and Hot Briquetted Iron (HBI) is an important complement to the use of scrap in steelmaking. Refined iron ore such as DRI and HBI has a more consistent quality than scrap, the composition of which can vary widely. Iron ore-based feedstocks allow more precise control and refinement of the production process, resulting in higher product quality. Although the use of DRI and HBI still requires the extraction of raw materials, their use significantly improves the carbon footprint of steel production. This is because direct reduction facilities, which currently run on natural gas, are being converted to hydrogen. This conversion will further reduce carbon emissions and contribute to a lower carbon footprint. In addition, the use of electrical energy is being made more efficient through condition monitoring. Precise monitoring of furnace conditions allows energy consumption to be optimized, resulting in virtually CO2-neutral operation of the EAFs. These improvements not only make steel production greener, but also more sustainable, as the entire process is designed for lower emissions.
Conclusion: Demand for green steel continues to rise
The future of steelmaking will inevitably lead to increased use of EAFs, although there are still some challenges to overcome. From an economic point of view, it is becoming increasingly attractive for steelmakers to switch to these processes. This is due to political measures such as subsidies, but also to increasing customer demand for more environmentally friendly products. Large steel mills are already starting to gradually convert their steel plants to meet the new standards and reap the economic benefits of sustainable production. The member states of the European Union are leading the way in promoting this transformation. They are creating incentives for steel producers to modernize their production routes.
Technically speaking, the increased use of EAFs in steel production is an evolution, not a revolution. However, there is still considerable development potential to make the new furnace generation even better and more environmentally friendly, in particular by further reducing the use of coal and increasing energy efficiency. Qlar has a great deal of experience with these technologies. The proven and reliable systems are continuously developed to meet the increased process requirements and the growing demand for green steel.
